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Extending the boundaries of diaryliodonium reagents : expressing I-nucleophilicity of aryl iodides and… Racicot, Léanne 2016

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EXTENDING THE BOUNDARIES OF DIARYLIODONIUM REAGENTS: EXPRESSING I-NUCLEOPHILICITY OF ARYL IODIDES AND METAL-FREE PREPARATION OF SULFONIUM SALTS  by  Léanne Racicot  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Chemistry)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  September 2016  © Léanne Racicot, 2016 ii  Abstract  Diaryliodonium salts are a well-established class of hypervalent iodine reagents and act as aryl group transfer agents towards nucleophiles.  This work established the possibility of metathesis between diaryliodonium triflates and various iodoarenes. In an effort to further understand the factors that govern this process, l3-iodanes containing 2-thienyl moieties were prepared.  As a result, aryl iodides unable to undergo metatesis previously were found to be suitable nucleophiles as the metathesis favors diaryliodonium species where more nucleofugal aryl iodides, such as 2-iodothiophene, are expelled during the course of the reaction. In addition, we showed that copper catalysis was not necessary for the arylation of sulfides, selenides and tellurides.  Indeed, thermal reactions between the chalcogenides and diaryliodonium triflates afforded the corresponding triarylchalcogenium salts in good yields.  This is particularly significant for the preparation of the triaryltelluronium species, as only limited protocols for their preparation were known. iii  Preface The present thesis was written by Racicot, L. as a result of the research conducted in the laboratories of Professor Ciufolini, M. A. Prof. Ciufolini, M. A. also provided project design, recommendations through the course of the studies and thorough editing of the current manuscript. Racicot, L. was responsible for all experiments unless otherwise specified. A version of Section 2.2 was published as: Kasahara, T.; Jang, Y. J.; Racicot, L.; Panagopoulos, D.; Liang, S. H.; Ciufolini M. A. Angew. Chem. Int. Ed. 2014, 53, 9637. Data presented in Table 2.3, entries a–h, and Scheme 2.6 was obtained by Kasahara, T., Jang, Y. J. was responsible for data presented in Table 2.4.  The semi-empirical calculations reported in Figure 2.1 were obtained by Prof. Ciufolini, M. A. and he also redacted the article.  Kasahara, T. and Racicot, L. shared the assembly of the supplementary information for the article.  Panagopoulos, D. contributed to early experiments in the metathesis project, and Liang, S. H. provided inspiration leading to the development of the project.  Section 2.3 is based on currently unpublished results. Section 3.1 was modified from the article previously published: Racicot, L.; Kasahara, T.; Ciufolini, M. A. Org. Lett. 2014, 16, 6382.  Prof. Ciufolini, M. A. prepared the manuscript, while experiments were conducted by Racicot, L.; the supplementary information was combined by her.  Kasahara, T. prepared some of the starting material employed for the study (diaryliodonium triflates 3.24 a–d). iv  Table of Contents Abstract .......................................................................................................................................... ii	Preface ........................................................................................................................................... iii	Table of Contents ......................................................................................................................... iv	List of Tables ................................................................................................................................ vi	List of Figures .............................................................................................................................. vii	List of Schemes ........................................................................................................................... viii	List of Abbreviations .....................................................................................................................x	Acknowledgements .................................................................................................................... xiii	Dedication ................................................................................................................................... xvi	Chapter 1: Introduction ................................................................................................................1	1.1	 Iodine and Hypervalency ................................................................................................ 1	1.2	 Classification of Hypervalent Iodine Compounds .......................................................... 3	1.2.1	 Iodine(III) Compounds ........................................................................................... 4	1.2.2	 Iodine(V) and Iodine(VII) Compounds .................................................................. 9	1.3	 Diaryliodonium Salts .................................................................................................... 11	1.3.1	 Preparation Methods ............................................................................................. 12	1.3.2	 Use as Arylating Agents ....................................................................................... 16	Chapter 2: Iodonium Metathesis ................................................................................................25	2.1	 Genesis of the Project ................................................................................................... 25	2.1.1	 Background ........................................................................................................... 27	2.2	 Iodonium Metathesis Reactions: Initial Studies ........................................................... 29	2.3	 Mechanistic Aspects of the Iodonium Metathesis Reaction ......................................... 37	v  2.4	 Iodonium Metathesis with Unreactive Aryl Iodides ..................................................... 43	2.5	 Conclusions and Future Direction ................................................................................ 54	Chapter 3: Metal-Free Preparation of Triarylchalcogenium Salts .........................................57	3.1	 Background on Triarylchalcogenium Salts ................................................................... 57	3.2	 Arylation of Chalcogenides .......................................................................................... 58	3.3	 Future Work .................................................................................................................. 69	Conclusion ....................................................................................................................................72	References .....................................................................................................................................73	Appendix A: Semi-empirical Estimation of the Charge on Iodine Atoms of Selected Organoiodine Compounds ..........................................................................................................83	Appendix B: Use of 1H and Quantitative 13C NMR Spectroscopy for the Calculation of the Ratios of Diaryliodonium Triflates in Isolated Mixtures .........................................................84	Appendix C: Experimental Section ............................................................................................87	Appendix D: 1H and 13C Spectra from Chapter 2..................................................................141 Appendix E: 1H and 13C Spectra from Chapter 3..................................................................211  vi  List of Tables Table 2.1 Evaluation of conditions for diaryliodonium metathesis reaction ................................ 30	Table 2.2 Scope of the diaryliodonium metathesis: variation of aryl iodide with Ph2IOTf ......... 31	Table 2.3 Iodonium metathesis with 4-nitrophenyl substituted diaryliodonoium salts ................ 34	Table 2.4 Iodonium metathesis reaction with (4-carbomethoxyphenyl)(2-thienyl)iodonium triflate ............................................................................................................................................ 37	Table 2.5 Metathesis of unreactive aryl iodides with di(2-thienyl)iodonium triflate under thermal conditions ...................................................................................................................................... 46	Table 2.6 Metathesis of unreactive aryl iodides with phenyl(2-thienyl)iodonium triflate under thermal conditions ......................................................................................................................... 48	Table 2.7 Metathesis of unreactive aryl iodides with di(2-thienyl)iodonium triflate with microwave irradiation ................................................................................................................... 49	Table 2.8 Metathesis of unreactive aryl iodides with phenyl(2-thienyl)iodonium triflate with microwave irradiation ................................................................................................................... 50	Table 2.9 Metathesis of unreactive aryl iodides with (mesityl)phenyliodonium triflate under thermal conditions ......................................................................................................................... 52	Table 2.10 Metathesis of unreactive aryl iodides with (mesityl)phenyliodonium triflate with microwave irradiation ................................................................................................................... 53	Table 3.1 Empirical optimization of the aryl transfer to diphenylsulfide ..................................... 60	Table 3.2 Aryl transfer to sulfides using symmetrical diaryliodonium triflate salts .................... 61	Table 3.3 Aryl group transfer selectivity survey .......................................................................... 62	Table 3.4 Catalyst-free arylation of Ph2Se and Ph2Te .................................................................. 66	 vii  List of Figures Figure 1.1 The Rundle-Pimentel model for 3c-4e hypervalent bonds ............................................ 2	Figure 1.2 Examples of hypervalent organoiodine compounds ...................................................... 3	Figure 1.3 Representative structural types of organoiodine(III) compounds ................................. 5	Figure 1.4 Hypervalent bonding in 10-I-3 iodanes ......................................................................... 6	Figure 1.5 Examples of alkenyl- and alkynyliodonium salts .......................................................... 9	Figure 1.6 Compounds containing heptavalent iodine ................................................................. 11	Figure 2.1 Algorithm for the semi-empirical calculations of the charge on the I-atom of aryl iodides ........................................................................................................................................... 40	Figure 2.2 Calculated values of charge on the iodine atom .......................................................... 42	Figure 3.1 1H NMR (300 MHz, acetone-d6) signals of the presumed adduct formed by substitution of dichloroethane with Ph2Te .................................................................................... 68	 viii  List of Schemes Scheme 1.1 Reactions of iodonium ylides ...................................................................................... 6	Scheme 1.2 Reactions of l3-iodanes with two heteroatomic ligands ............................................. 7	Scheme 1.3 Preparation of diaryliodonium salts from iodosylbenzene .......................................... 8	Scheme 1.4 Aryl transfer to a generic nucleophile using diaryliodonium triflates ........................ 8	Scheme 1.5 Preparation of IBX and DMP .................................................................................... 10	Scheme 1.6 Preparation of diaryliodonium salts from the Beringer group .................................. 12	Scheme 1.7 Kitamura's methods for one-pot preparation of diaryliodonium triflates .................. 14	Scheme 1.8 Olofsson's methods for one-pot preparation of diaryliodonium triflates .................. 15	Scheme 1.9 Preparation of diaryliodonium salts with organometallic species ............................. 15	Scheme 1.10 Ligand exchange on iodine(III) species .................................................................. 16	Scheme 1.11 Reductive elimination on hypervalent iodine molecules ........................................ 17	Scheme 1.12 Diastereoselective arylation of enolates employing diaryliodonium salts .............. 18	Scheme 1.13 Arylation of anilines and phenols ............................................................................ 19	Scheme 1.14 Sulfur, selenium, and tellurium nucleophiles .......................................................... 20	Scheme 1.15 Radiofluorination using diaryliodonium salts ......................................................... 22	Scheme 1.16 DiMagno F-promoted ligand exchange on diaryliodonium species ....................... 22	Scheme 1.17 Beringer-Ochiai mechanism for the selective aryl transfer ..................................... 23	Scheme 2.1 Cascade aldol oligomerization catalyzed by triflimide and iodobenzene ................. 26	Scheme 2.2 Proposed iodonium metathesis .................................................................................. 26	Scheme 2.3 Preparation of radiofluorinated compounds via a hypervalent iodine precursor ...... 26	Scheme 2.4 Aryl transfer between HTIB and 1-chloro-4-iodobenzene ....................................... 27	Scheme 2.5 The Moriarty mechanism for redox metathesis between iodocubane and HTIB ...... 28	ix  Scheme 2.6 Reaction between di(4-anisyl)iodonium triflate and 4-iodotoluene .......................... 33	Scheme 2.7 Possible mechanistic pathways with unsymmetrical ortho-substituted diaryliodonium salt ................................................................................................................................................. 35	Scheme 2.8 General mechanism postulated for the iodonium metathesis reaction ...................... 38	Scheme 2.9 Stang's preparation of di(2-thienyl)iodonium triflate ................................................ 43	Scheme 2.10 Preparation of di(2-thienyl)iodonium triflate by Olofsson-type methodology ....... 44	Scheme 2.11 Reaction between dithienyliodonium triflate and 4-iodotoluene ............................ 45	Scheme 2.12 Preparation of meta-substituted diaryliodonium triflates via iodonium metathesis 55	Scheme 2.13 Iodonium metathesis attempts with 5-iodo-2,4-dimethoxypyrimidine ................... 55	Scheme 3.1 Examples of cationic polymerization initiated by the triarylsulfonium salts ............ 57	Scheme 3.2 Photolysis of triarylsulfonium salts ........................................................................... 58	Scheme 3.3 Comparison of mechanisms of iodonium metathesis with sulfide arylation by diaryliodonium salts ...................................................................................................................... 59	Scheme 3.4 Mechanism of the nucleophilic aromatic substitution pathway with diarylsulfides . 63	Scheme 3.5 Arylation of thioanisole with di(4-bromophenyl)iodonium triflate .......................... 64	Scheme 3.6 Sanford's acid-catalyzed synthesis of diarylsulfides ................................................. 64	Scheme 3.7 Arylation of 4-bromothioanisole with diphenyliodonium triflate ............................. 65	Scheme 3.8 Mechanism of the Corey-Chaykovsky reaction ........................................................ 69	Scheme 3.9 Proposed cyclization via arylation of sulfides ........................................................... 70	Scheme 3.10 Cyclization of citronellyl sulfide promoted by arylation with di(4-bromophenyl)iodonium triflate113 ................................................................................................. 70	Scheme 3.11 Cyclization of citronellyl sulfide with di(4-bromophenyl)iodonium triflate in the presence of calcium carbonate ...................................................................................................... 71	x  List of Abbreviations Ac  acetyl Ar  aryl b.p.  boiling point ca.  circa conds.  conditions conv.  conversion DCE  1,2-dichloroethane DIB  (diacetoxyiodo)benzene DMF  N,N-dimethylformamide DMP  Dess-Martin periodinane e  elementary charge EAS  electrophilic aromatic substitution EDG  electron-donating group equiv  mole equivalent(s) ESI  electrospray ionisation EWG  electron-withdrawing group GC  gas chromatography HRMS  high-resolution mass spectrometry HTIB  [hydroxy(tosyloxy)-iodo]benzene K222  Kryptofix-222; 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane mCPBA meta-chloroperbenzoic acid Me  methyl xi  MeCN  acetonitrile MNDO/d modified neglect of diatomic overlap, with inclusion of d orbitals MO  molecular orbital m.p.  melting point MS  mass spectrometry Mt  metal MW  microwave irradiation m/z  mass-to-charge ratio ND  not determined NMR  nuclear magnetic resonance NR  no reaction PET  positron emitting tomography Ph  phenyl  RBF  round-bottom flask rt  room temperature SET  single electron transfer sln  solution SNAr  nucleophilic aromatic substitution Tf  trifluoromethanesulfonyl TFA  trifluoroacetic acid TFE  2,2,2-trifluoroethanol THF  tetrahydrofuran tr  trace xii  Ts  para-toluenesulfonyl xiii  Acknowledgements I first need to express my deepest gratitude for my advisor, Professor Marco A. Ciufolini for welcoming me in his group over the past five years.  Every discussion we have, I am inspired by your wisdom and scientific rigor, and have always appreciated your forthright opinion.  You have not only been an example of mastery of chemistry and science in general, but also a model of teaching and leadership skills.  The support provided for every member is remarkable, we each have the space to learn and develop so much, between the group meetings, frequent interactions with you and the occasional demonstrations in the lab.  Thank you for your patience and trusting me to dispense two CHEM 203 lectures, as well as allowing me to take on more particular teaching duties in the department.  I can only hope that my future endeavors will convey the quality of education one receives in your research group. I would also like to express my appreciation for the other members of my committee, Professor Glenn Sammis, Professor Laurel Schafer and Professor Katherine Ryan.  I appreciated your advice and questions during the meeting paving the way to the completion of this degree.  I am particularly indebted to Professor Sammis, who was able to serve as second reader even given the extremely short deadline.  He was also able to provide the microwave reactor which helped improve the thienyl iodonium methodology. My completion of this degree would not have been imaginable without the wonderful labmates I worked with.  I particularly am thankful for Takahito Kasahara, from whom I learned countless techniques in the lab.  Our personalities could not have been more different, but I cannot imagine working in a synthetic lab without you.  I have also had the pleasure of working with Dr. Matthew Smith and Dr. Josh Zaifman, who were always available to answer my questions and provide help with troubleshooting the experiments I was struggling with.  To xiv  Alvin Jang, Dimitris Panagopoulos, Hojung Lee, Matei Vacariu, and Yiming Ren: I am grateful to have had the chance to work with you all on diaryliodonium salts-related projects.  The other Ciufoliners are not to be forgotten, I will keep fond memories of our discussions (on chemistry or otherwise), and of your attitudes while going through the ups and downs of research.  I have learned from each and of you, I can only hope to have such a colorful group of people as coworkers in the future. Thank you Sanjia Xu, Marco Paladino, Jason Hwang, Nikita Jain, Dr. Dylan Turner, Gloria Zedda, and all the others with whom I overlapped during my time as part of the Ciufolini group. The extremely competent staff working in the Chemistry Department deserves many praises for the scientific support they provide daily.  Dr. Paul Xia was an indispensable to find an appropriate method to analyze my complex mixtures, as well as helping with issues with our NMR, along with Milan Coschizza and David Tonkin of the electronic engineering services.  I am thankful for the quality of service provided by Dr. Yun Ling, Marshall Lapawa and Derek Smith of the mass spectrometry lab; Dr. Brian Patrick for the x-ray crystallography; as well as John Ellis and Pat Olsthoorn for the chemical acquisition and reception. To all my friends in the department, thank you for sharing your time, your knowledge and your good vibes with me.  I am also grateful for the freshman labs teaching team (Dr. Sophia Nussbaum, Anne Thomas, Kris Asperin, Emily Lai, Elesha Hoffarth, Amber Shukaliak and Fraser Parlane) for trusting me with the mentoring project, which both challenged me and helped me gain confidence.  And of course there is also my “network” of incredible chemist ladies who always inspire me, and I definitely do not acknowledge you all enough, thank you for helping keep striving for the best, Zemane, Kassandra, Laurence, Catherine, and Stéphanie.  Une pensée spéciale pour Dr. Claire Chatalova qui sait toujours comment me remonter le moral et me xv  motiver.  I also need to give extra cheers to Martina Chambers, our connection was cosmic and I am so glad to have seen you go through such big leaps in your life.  Thanks for all the wine, the food and the laughs.  And a huge thanks for proofreading my intro and ensuring it was palatable to those who have yet to sell their soul to hypervalent iodine.  I have been very fortunate to receive funding throughout my education, either by government grants (NSERC, Vanier), from UBC (Four Year Fellowship, Killam GTA), or from the Chemistry Department (Gladys Estella Laird scholarship).  Those initiatives allow students to focus on studies without the burden of financial struggle and for that I am extremely grateful. I probably would not have ended up in Professor Ciufolini’s laboratory if it was not for Dr. Sylvain Canesi.  Thank you for trusting me with more than washing glassware when I was just a silly teenager, and being patient while I was learning the basics of organic chemistry in your laboratory.  I definitely do not know where I would be if our paths had not crossed, and I am infinitely grateful for all the advice I received from you, and for all the letters of references you have written for me through the years Je ne peux pas terminer mes remerciements sans mentionner ma mère Maude Ouellet, sans qui je ne serais pas en mesure de compléter ces longues études.  Ton support m’a donné des ailes.  xvi  Dedication     “I always thought I was intellectual about what I do, but I’ve come to the realization that I have absolutely no idea what I’m doing half the time.” ― David Bowie, September 29th, 1984   1  Chapter 1: Introduction 1.1 Iodine and Hypervalency The classical Lewis-Langmuir theory of covalent interactions proposes that chemical bonding occurs when atoms share one or more electrons occupying their outermost shell.  In most cases, the bonded atoms thus acquire an electronic configuration equivalent to that of nearest noble gas; namely, a “stable octet”1 of outermost electrons (or “Lewis octet”).  This fact is often described in terms of the atoms “completing their valence shell.” Following this definition, iodine, an element in Group 17 of the periodic table, should form a single bond in order to complete its valence shell.  Whereas most organoiodine compounds indeed exhibit a monovalent iodine atom, the element possesses the ability to establish bonded states in which it forms more than one bond.  This was observed as early as 1814, when J. L. Gay Lussac reported the preparation of both iodine trichloride and potassium iodate.2  In such molecules, iodine is described as being “hypervalent” or “polyvalent”, meaning that it accommodates more than a Lewis octet of electrons.  Iodine is not unique in that regard: the heavier group 15-18 elements also display a propensity to form hypervalent states.  Examples include molecules such as PCl5, SF6, FClO3, XeF4, etc.  It is believed that iodine can readily acquire hypervalent oxidation states of +3, +5 and +7 due to its large atomic radius and a combination of low electronegativity and high polarizability.3  Indeed, the most prevalent mineral source of iodine is anhydrous calcium iodate, or lautarite, Ca(IO3)2.4  As such, iodine is the only halogen that can be found naturally in polyvalent state.  A formal description of the electronic and geometric properties of hypervalent molecules was only developed in 1969.5  A classical hybridization approach invokes the intervention of d 2  orbitals to accommodate the supernumerary electrons (“expanded octet”).  However, recent computational analyses have revealed that this offers no energetic advantage, at least for second or third row elements.6  The currently preferred bonding model for hypervalent compounds envisions the formation of linear, three-center-four-electron (3c–4e) bonds, referred to as the Rundle-Pimentel model.7  A generic hypervalent bond L–X–L may thus be thought of as arising through the mixing of a p orbital of the central atom X with the p orbitals associated with two ligands L, which are trans to each other (Figure 1.1).  Three molecular orbitals (MO) arise as a result, and the highest occupied molecular orbital (HOMO) is, in this case, a non-bonding orbital. The electrons occupying the HOMO are localized on the ligands, leaving a node on the central atom.  This effectively creates a high level of polarization within the bond: the ligands possess a charge of nearly –0.5 e each, while the central atom bears a +1.0 e charge.   Figure 1.1 The Rundle-Pimentel model for 3c-4e hypervalent bonds  While alternative models have been advanced, for instance, for xenon fluorides,8 most leaders in the field consider the Rundle-Pimentel hypothesis sufficient for the description of bonding in hypervalent iodine compounds.3, 9, 10   •bonding MOnonbonding MOantibonding MOL X L3  1.2 Classification of Hypervalent Iodine Compounds The preparation of (dichloroiodo)benzene in 188611 marked the beginning of the now thriving field of polyvalent organoiodine research.  For nearly 100 years, efforts in the area focused on the preparation and structural characterization of new hypervalent iodine compounds.12  However, extensive investigation of the reactivity of these species only flourished beginning in the late 1970’s-early 1980’s, mostly due to the discovery that an iodine(V) species now known as Dess-Martin periodinane (Figure 1.2) could cause facile oxidation of alcohols to the corresponding carbonyl compounds.13    Figure 1.2 Examples of hypervalent organoiodine compounds  Numerous synthetic applications of hypervalent iodine agents have been developed since.  Many of these compounds are strong oxidants that enable the conduct of reactions analogous to those previously achieved by heavy metal reagents such as lead(IV) acetate,14 but in a more environmentally benign manner.  Certain transformations are possible only through the use of hypervalent organoiodine species.  For instance, the oxidative dearomatization of phenols and aniline derivatives with concomitant formation of new C–C,15 C–O,16 and C–N17 bonds is best achieved with (diacetoxyiodo)benzene (DIB) and related species (Figure 1.2).  OIOAcOOAcAcODess-Martinperiodinane (DMP)IOAcOAc(diacetoxyiodo)-benzene (DIB)4   The following section outlines the diversity of known hypervalent iodine species by touring their structural diversity and their reactivity according to the oxidation state of the iodine center.  1.2.1 Iodine(III) Compounds The naming system employed for polyvalent iodine compounds has obviously evolved significantly over the 200-year history of the field.  For instance, trivalent iodine compounds such as DIB have been variously referred to as iodinanes, iodine(III) species, etc.  Since the 1980's, hypervalent iodine compounds have been collectively described as “iodanes,” and are classified using either of two conventions: IUPAC’s lambda (l) designation,18 and the less commonly employed Martin-Arduengo N-X-L nomenclature.19  The lambda convention identifies a hypervalent species as a ln compound, wherein l is indicative of a “nonstandard” bonding number of an element engaged in n s or p bonding interactions.  Under this criterion, all iodine(III) compounds, such as the ones shown in Figure 1.3,20 are referred to as l3-iodanes.  In the N-X-L nomenclature, N represents the total number of electrons in the valence shell of the central atom X, and L is the number of ligands.  Accordingly, the iodanes of Figure 1.3 would be described differently.  To wit, the dimedone iodonium betain 1.1a is qualified as an 8-I-2 iodane, but its resonance structure 1.1b as a 10-I-2 species, as is iodosylbenzene, 1.2.  Compounds such as DIB and diphenyliodonium triflate are then 10-I-3 iodanes.  5   Figure 1.3 Representative structural types of organoiodine(III) compounds  Several iodonium ylides structurally related to 1.1 have been obtained in crystalline state and their X-ray structure has confirmed the approximated 90° C–I–C bond angle.21 This observation is in agreement with the model which places the nonbonding electron pairs in the same plane as one of the ligands, while the second substituent finds itself in an axial position. The ylide I–C bond is also shortened to about 1.9 Å, versus around 2.1 Å for bond in monovalent organoiodine moleculecules, signifying a higher bond order. 10-I-3 iodanes are perhaps the most prevalent of the trivalent iodine compounds.  They possess one hypervalent bond and one covalent bond, which, together with two nonbonding electron pairs, impart a trigonal bipyramidal geometry to their molecules.  The ligand involved in the covalent bond and the two electron pairs are arranged in a trigonal fashion around the iodine atom, and occupy so-called equatorial positions (Leq).  Two other ligands are involved in the 3c–4e bond, and occupy apical positions (Lap).  The three ligands are thus arranged in a T-shape geometry.  The more electronegative ligands around the I-atom exhibit a strong preference for the apical positions.  This is a direct consequence of the significant accumulation of negative charge on ligands involved in hypervalent bonding (see Section 1.1): the more electronegative the ligand, the more readily it can sustain negative charge (Figure 1.4).   IO10 -I-2iodosylbenzene1.2I8-I-2                                  10-I-2dimedone phenyl-iodonium betaine1.1a                                    1.1bO O10 -I-3(diacetoxyiodo)-benzene (DIB)1.3IOAcOAc10 -I-3diphenyliodoniumtriflate1.4IOTfIO O6   Figure 1.4 Hypervalent bonding in 10-I-3 iodanes  The reactivity of iodine(III) compounds is markedly influenced by the nature of the ligands around the I atom.  For instance, appropriate activation of iodonium ylides such as 1.1 tends to produce carbenes.  These can subsequently participate in cyclopropanation, formal C–H insertion, and [3+2] cycloadditions reactions (Scheme 1.1).22  Scheme 1.1 Reactions of iodonium ylides  Iodosylbenzene 1.2, a substance first described by Willgerodt,23 has been used as an oxygen-transfer agent on a variety of substrates.24  Overshadowing its use are the facts that it exists in polymeric form, and thus it is nearly insoluble in most solvents, and that it is explosive.  Monomeric, soluble forms thereof result upon treatment with a Lewis acid, ligation with a halide ion, interaction with certain transition metal complexes, or dissolution in a hydroxylic solvent.20  More significantly, it can be chemically elaborated to a range of safer, soluble l3-iodanes, such Leq ILapLapδ+δ-δ-OOIPh OOOORR(a)OOArAr–H(b)OX=C=Y(c)XOY[Cu], [Rh],or other Mt7  as DIB and related compounds with one carbon substituent,25 which are valuable oxidants and uniquely competent for the conduct of various transformations.  In addition to the oxidative dearomatization of electron-rich aromatics, DIB and congeners find application in C–H oxygenation, oxidation of alcohols, 1,2-difunctionalization of olefins and alkynes and epoxidation reactions.24   Scheme 1.2 Reactions of l3-iodanes with two heteroatomic ligands  Especially relevant to the research that will be presented in the following chapters are the diaryliodonium salts.  These 10-I-3 species are exemplified by diphenyliodonium triflate 1.4 (Figure 1.3), and may be prepared from iodosylbenzene (or an equivalent iodosylaromatic compound) by a Friedel-Crafts-like reaction with a second arene (Scheme 1.3).    Ar IXXREWGREWGXR1 R2OHR1 R2OR2R1R2R1 XXEWGR1EWGR1OR1R2XR1X R28   Scheme 1.3 Preparation of diaryliodonium salts from iodosylbenzene  Diaryliodonium salts have been investigated for more than a century, given their unique ability to transfer an aryl group, even an unactivated one, to various nucleophiles. This is attributed to the exceptional nucleofugal character of an Ar–I (notice that an Ar–I functions as a leaving group during the reaction depicted in Scheme 1.4), which is estimated to depart 106 times faster than triflate ion.26  The electrophilic character of diaryliodonium salts stands in contrast to the behavior of aromatic iodides, which are not considered to be particularly electrophilic unless the aryl segment carries one or more ortho / para electron-withdrawing groups to promote SNAr chemistry.  Additional details concerning the preparation and reactivity of diaryliodonium salts will be provided in Section 1.3 (p. 11).     Scheme 1.4 Aryl transfer to a generic nucleophile using diaryliodonium triflates  I+H–X I XH–X = H2SO4, AcOH, TfOH, TsOH,           TFAOR1R2HR2R1OTfArIRNu- OTf- NuArIR NuArIR δ+δ-δ-RNuI Ar+ligand exchangeligand coupling9  We conclude this section by mentioning that l3-iodanes incorporating alkenyl and alkynyl groups are also known (Figure 1.5), but the heightened reactivity of such complexes limits their synthetic use.27   Figure 1.5 Examples of alkenyl- and alkynyliodonium salts   1.2.2 Iodine(V) and Iodine(VII) Compounds In accord with the designations introduced in Section 1.2.1 (p. 4), pentavalent iodine compounds, previously known as periodinanes, are commonly referred to as l5-iodanes. To allow for the two hypervalent bonds to adopt a co-linear L–I–L arrangement, these molecules usually display a distorted square pyramidal or disphenoidal geometry, depending on the number of ligands around the iodine(V) center. Two notably useful l5-iodanes in synthetic organic chemistry are 2-iodoxybenzoic acid (IBX) and its triacetoxy derivative, Dess-Martin periodinane (DMP) (Scheme 1.5). Both are versatile oxidants, allowing, the conversion of alcohols into carbonyl compounds, the a-hydroxylation of ketones in the presence of base, the dehydrogenation of ketones into the corresponding enones, among other known uses.28  DMP is more widely employed due to its enhanced solubility in organic solvent.  IPhBF4R2R1R1 IPhOTf10   Scheme 1.5 Preparation of IBX and DMP  The original method for the preparation of these compounds involved the oxidation of o-iodobenzoic acid 1.5 to IBX using potassium bromate.29  Occasionally, the produced IBX would explode violently.  This hazardous property proved to be a consequence of contamination of IBX by bromine-containing species.30  The use of OXONEâ in lieu of bromate ion all but suppresses the risk of explosions and affords IBX of better purity.31  Treatment with acetic anhydride advances IBX to DMP.   At this time, iodine(VII) is known only in inorganic molecules, such as periodic acid and iodine heptafluoride, for which the IUPAC lambda nomenclature is not generally employed.  Periodic acid can present itself either as HIO4 (metaperiodic acid 1.8, Figure 1.6) or H5IO6 (orthoperiodic acid 1.9, Figure 1.6). It is a classic reagent for the oxidative cleavage of vicinal diols, epoxides, a-hydroxycarbonyl compounds, and other 1,2-difunctional entities.32  Iodine heptafluoride is obtained by a procedure that is difficult and hazardous. It is a strong oxidant that easily ignites organic matter, rendering its use as a reagent in organic chemistry quite problematic.33  Noteworthy is the fact that only fluorine combines with iodine to form a (relatively) stable heptahalide.    OICO2HIOOOHOIOAcOOAcAcOOXONE®H2OAc2OAcOH1.5 12-I-42-iodoxybenzoic acid(IBX)1.612-I-5Dess-Martinperiodinane (DMP)1.711   Figure 1.6 Compounds containing heptavalent iodine  1.3 Diaryliodonium Salts As introduced in Section 1.2.1 (p.11), diaryliodonium salts are iodine(III) species possessing two aromatic ligands as well as an inorganic counterion.  It should be noted that the term “diaryliodonium salts” is somewhat of a misnomer, in that X-ray crystal structures of these compounds typically present bond lengths between iodine and the ionic counterion of 2.6–2.8 Å. These are typical of higher ionic character of the bonding interaction (I–X bonds generally have lengths around 2 Å); however, their geometry is found to be T-shape, indicating some amount of covalent bonding between I–X.3  Since their discovery, these iodanes have attracted significant attention from synthetic organic chemists, on account of their ability to function as electrophilic aryl transfer agents.  This has provided an incentive to find efficient, general ways to prepare them.  The current section highlights key methods for the synthesis of diaryliodonium salts and provides a short summary of their reactivity.  More details can be found in Olofsson’s excellent 2009 review.34  OIOHHO OHHO OH14-I-6orthoperiodic acid1.9FIFF FFF14-I-7iodineheptafluoride1.10FOIOOHO14-I-4metaperiodic acid1.812  1.3.1 Preparation Methods The first preparation of a 10-L-3 iodane possessing two aromatic ligands was reported in 1894 by Hartmann and Meyer,35 who discovered that dissolution of iodosylbenzene in concentrated sulfuric acid produces (4-iodophenyl)phenyliodonium hydrogen sulfate.   The preparation of iodonium salts can be achieved through numerous methods, although most rely on a suitable arene undergoing electrophilic aromatic substitution (EAS) with an iodine(III) species.  This chemistry was initially established by Beringer in the 1950’s in a series of influential articles, detailing among other approaches the use of inorganic hypervalent iodine precursors (Scheme 1.6a),36 the reaction of preformed organic hypervalent iodanes with arenes (Scheme 1.6b)36 or organometallic species (Scheme 1.6c),37 as well as the in situ oxidation of iodoarenes with potassium persulfate or barium peroxide (Scheme 1.6d) 38.   Scheme 1.6 Preparation of diaryliodonium salts from the Beringer group  Contemporary methods rely on improved variants of the same procedures.  Today, various l3-iodanes suitable for the preparation of diaryliodonium salts are commercially 1. Ac2O, H2SO42. NH4Cl (aq)Ph IPhClKIO3 +2 equivAr1I O +AcOH, Ac2Oor H2SO4Ar2 H Ar1 IAr2Xb)Ar1IK2S2O8or BaO2, H2SO4Ar1 I(OSO3H)2Ar2H KIAr1 IAr2Id)Ar1I O +etherthen H–XAr2 Li Ar1 IAr2Xc)Ar2 MgXAr1IX2X = Cl, Bra)13  available.  However, in situ oxidation of an aryl iodide to an iodine(III) intermediate, followed by the addition of an appropriate arene under acidic conditions, and without isolation of the above intermediate, is attractive.  One-pot procedures permit the formation of more reactive iodine(III) intermediates, therefore improving the EAS with the arene.  It should be noted that the nature of the anionic ligand X has a major influence on the reactivity of the iodanes shown in Scheme 1.6. In particular, diaryliodonium triflates exhibit many desirable properties, and their use is becoming ever more prevalent.39  Fortunately, many methods exist to induce anion exchange reactions of diaryliodonium salts; for instance, to convert sulfates, halides, tosylates, acetates, etc., into triflates.  A simple method consists in adding triflic acid to a solution of a diaryliodonium salt in an aprotic solvent, typically a halogenated one.40  The powerfully Brønsted acidic TfOH readily protonates ligand X, causing it to depart as H–X.  The TfO– produced as a result will then ligate the I-atom, leading to a diaryliodonium triflate. A number of oxidants may be used in the approach involving the one-pot oxidation of aryl iodides to l3-iodanes, followed by EAS with an arene (similar to Scheme 1.6d).  For instance, Kitamura and coworkers (Scheme 1.7) employed potassium persulfate41 in an improved modification of the Beringer protocol (see Scheme 1.6). Symmetrical diaryliodonium salts can be prepared by the oxidation of diiodine presumably to the +3 state, followed by trifluoroacetic acid-catalyzed condensation with an aromatic compound.42  Unfortunately, either technique suffers from limited scope and long reaction times.  Furthermore, the product iodane is obtained as a diaryliodonium trifluoroacetate, necessitating a separate anion exchange step to create the corresponding triflate.  It seems plausible that the use of TfOH in lieu of TFA may produce a 14  diaryliodonium triflate directly.  However, only a limited number of symmetrical diaryliodonium salts were thus prepared from iodine and arenes.43   Scheme 1.7 Kitamura's methods for one-pot preparation of diaryliodonium triflates  Olofsson and coworkers achieved direct preparation of diaryliodonium triflates from aryl iodides44 by oxidizing an aryl iodide with meta-chloro-peroxybenzoic acid (mCPBA),45 followed by treatment of the in situ formed iodoso derivative with a reactive arene and triflic acid (Scheme 1.8, method a).  The method was unsatisfactory for the synthesis of symmetrical diaryliodonium triflates from diiodine and an electron-rich arene.46  The problem was resolved by operating in the presence of the weaker tosic acid, followed by anion exchange without isolation of the intermediate tosylate salt (Scheme 1.8, method b).  Ar1I +1. K2S2O8 (4 equiv), TFA, 38°C, 20h 2. aq. NaOTf, 8hAr2 H Ar1 IAr2OTfI2 + 4 Ar HAr IArOTfa)b)3 equiv20 equiv1. K2S2O8 (10 equiv), TFA, 40°C, 72h 2. aq. NaOTf, 12h14 examples,58-78%5 examples,54-81%I2 + 4 Ar HAr IArOTfc)20 equivK2S2O8 (10 equiv),TfOH (20 equiv)DCE/AcOH, 40°C, 48h8 examples,47-81%15   Scheme 1.8 Olofsson's methods for one-pot preparation of diaryliodonium triflates  The above Kitamura and Olofsson methods rely on EAS chemistry; consequently, they are limited by the electronic properties of the Ar–H component.  Electron-donating groups on the latter induce para-selectivity in the substitution reaction, while electron-withdrawing groups deactivate the aromatic nucleus and afford reduced yields of meta-substituted derivatives, often accompanied by numerous byproducts.  If the l3-iodane is to be prepared by the one-pot procedure, the incoming arene must also be more reactive in electrophilic aromatic substitution that the starting aryl iodide, to avoid competition in the EAS step.  Organometallic derivatives of the incoming arene, such as organolithium,47 boron,40 silicon,48 or tin49 species, nicely circumvent the regioselectivity concerns in the substitution reaction (Scheme 1.9).     Scheme 1.9 Preparation of diaryliodonium salts with organometallic species   Ar1I +mCPBA (1 equiv)TfOH (2-3 equiv)10 min - 19hAr2 H Ar1 IAr2OTfI2 + 4 Ar HAr IArOTfa)b)mCPBA (3 equiv)TsOH (4-6 equiv)then TfOH (1.2 equiv)32 examples,51-92%9 examples,24-93%Ar1IL2 +acidAr2 Mt Ar1 IAr2Xa)acid = H2SO4, AcOH          TfOH, TsOH,          BF3·OEt2, TFAL = OH, OTs, OAc,      OCOCF3, =O, OTfMt = Li, B(OH)2,       SiMe3, SnBu3Ar1I +oxidantacidAr2 Mt Ar1 IAr2Xb)16  1.3.2 Use as Arylating Agents A key aspect of the chemistry of diaryliodonium salts is that they behave as electrophilic arylating agents.  This reactivity may be understood in terms of two important properties.  First, iodine(III) centers undergo facile nucleophilic exchange of their heteroatomic ligands.  This process can be thought to occur through two possible pathways (Scheme 1.10).  The first involves a nucleophilic attack onto the partially positive hypervalent iodine center to afford anionic 12-I-4 iodane 1.12, in what is referred to as the associative mechanism.  Intermediate 1.12 then expels one of the original ligands to restore electrostatic neutrality and the new diaryliodonium 1.14 is obtained as a result.  In the alternative dissociative pathway, the order of the steps is reversed: a heteroatomic ligand first ionizes to produce a dicoordinated 8-I-2 species 1.13, which is then trapped by the nucleophile.   Scheme 1.10 Ligand exchange on iodine(III) species  Second, l3-iodanes of the type 1.14 tend to undergo reductive eliminination of Ar–I.  This process is analoguous to the well-known reductive elimination reaction in organometallic chemistry,50 and occurs with concomitant coupling of two ligands disposed in a syn mode around the hypervalent atom (Scheme 1.11). The term ligand coupling is often preferred when not Ar IArLNu-Ar I NuArLL-Ar IArNuassociative mechanismNu-L-dissociative mechanismArIAr1.121.131.141.1117  involving transition metals,10 but the term reductive elimination is not inherently incorrect.  Ligand exchange and ligand coupling are the foundation of the nucleophilic arylation chemistry of diaryliodonium salts.  Reductive a-elimination and reductive b-elimination (Scheme 1.11) are also a possibility for iodine(III) species, but are not involved as frequently in diaryliodonium reactivity.   Scheme 1.11 Reductive elimination on hypervalent iodine molecules  The a-functionalization of carbonyl compounds by formation of the enolate and subsequent reaction with an electrophilic reagent is a classic mode of reactivity for synthetic organic chemistry.  Reports of the use of diaryliodonium salts with activated methylene substrates appeared early in the discovery of the l3-iodane reagents: reports of the arylation of Meldrum’s acid, malonates and b-ketoesters were published in the beginning of the 1960’s by Beringer’s group.51  More recently, methodologies affording the stereoselective arylation of ketone enolates have been the subject of investigations, and complementary solutions have been put forward (Scheme 1.12).  Ar IArLligand couplingAr L Ar I+Ar IRLreductiveα-eliminationAr I+R+ + L-Ar IYLreductiveβ-eliminationY = C, N, OAr I+ + L-CHR RYRR18  First, the use of a chiral base (Scheme 1.12a) enabled the enantio- and diastereoselective arylation of a limited number of cyclohexanone derivatives. The methodology was highlighted in the diastereoselective preparation of (−)-epibatidine (Scheme 1.12a).52  More recently, the MacMillan group employed a chiral copper catalyst for the enantioselective arylation of silyl enol derivatives of N-acyloxazolidinones with diaryliodonium hexafluorophosphate salts (Scheme 1.12b).53    Scheme 1.12 Diastereoselective arylation of enolates employing diaryliodonium salts  Researchers have also identified conditions for the arylation of olefins and alkynes, facilitated by copper catalysts.54 Diaryliodonium salts can also be employed in palladium-catalyzed reactions such as Sonogshira, Stille and Suzuki cross-couplings, and many reviews have been written listing the variety of methods known to transfer aryl groups to carbon nucleophiles.34,55 Various heteroatomic nucleophiles are arylated by diaryliodonium salts.  Anilines readily react with trifluoroacetate derivatives (Scheme 1.13a) to afford the diaryl amines.56  Phenols require deprotonation, e.g. by potassium tert-butoxide before the ligand exchange and reductive ON(Boc)2Ph NLiPhNClICl2a)b)ON(Boc)2NClO NO OTBSRCuL*OTf (10mol%)Ar2IPF6O NO ORAr27 examples65-95% yield84-96% ee41% yield>20 : 1 dr94% ee19  elimination can occur (Scheme 1.13b).57  Conditions have been established for the arylation of a number of other N- and O-nucleophiles, such as aliphatic alcohols and amines, carboxylic acids and various heterocycles.24,34,58    Scheme 1.13 Arylation of anilines and phenols  Heavier chalcogens are also nucleophiles compatibles with diaryliodonium salts.  During their investigations on facile preparation of triarylsulfonium salts for use as photoinitiators for cationic polymerization, Crivello reported the arylation of sulfides under copper catalysis (Scheme 1.14a).59  By treating the selenolate or telluronate anions obtained by reductive cleavage of the dichalcogen bond with diaryliodonium halides, Chen and coworkers were able to obtain nonsymmetrical diarylselenides and tellurides in moderate to excellent yields (scheme 1.14b).60  Diaryl sulfides can be obtained by the S-arylation of thiols with l3-iodanes, and a number of variants of this methodology have been described.  In 2001, a mild base was used in conjunction with a palladium catalyst to efficiently transfer an aryl group to thiols (Scheme 1.14c).61  As demonstrated by Krief five years later, the reaction occurs without metal catalysts if a stronger base is used (Scheme 1.14d), but only one thiol was included in the report.62  Sanford reported in 2014 that acidic conditions also allow for the arylation of thiols and alkyl thioethers NH2+ Ar2I+CF3CO2-DMF130 °C, 24 hRHNRArOH 1. tBuOK2. Ar2IXRORAr12 examples50-92%a)b) 41 examples61-99%20  (Scheme 1.14e) with diaryliodonium trifluoroacetate salts.63  Admittedly, the more nucleophilic counterion allows for abstraction of the proton or the primary alkyl group on the transient sulfonium.  S-arylation of higher oxidation states of sulfur is also attainable using l3-iodanes; S-aryl dithiocarbamic esters,64 S-aryl thiocarboxylates,65 unsymmetrical S-aryl thiosulfonates,66 and diaryl sulfones67 can all be attained by reaction of the corresponding sulfur anion with appropriate diaryliodonium salts.    Scheme 1.14 Sulfur, selenium, and tellurium nucleophiles  Lastly, an additional class of nucleophiles for arylation by l3-iodanes is worthy of mention both for the implications in medicinal chemistry and to complete the second period along with carbon, nitrogen and oxygen.  The inclusion of fluorine in small molecules has caused Ar Y-Na+Ar'2I+X-DMF70-80 °CX = Cl-, I-Ar YAr'Y = Se: 6 examples,             58-75%Y = Te: 9 examples,             46-81%NaBH4DMF80-110 °CAr2Y2TFA (8 equiv)1,4-dioxane, 110 °CR SAr16 examples,37-90%+R SR1Ar2I+CF3COO-Cu(II) benzoate (2.5 mol%)neat120-125 °CAr2Y+Ar'Y = S: 15 examples,           65-100%Y = Se: 4 examples             49-90%+ Ar'2I+X-Ar2YY = S, Se X = BF4-, PF6-      AsF6-, SbF6-e)a)b)X-Y = Se, TeR = aryl, alkylR1 = H, 1° alkyld) nHex SHi. NaH, DMSOii. Ph2I+OTf-nHex SPh93%Ph2I+OTf-, PhMeCu(OAc)2 (5 mol%)nHex S+PhPh-OTf93%Pd(PPh3)4 (5 mol%)Na2CO3 (2 equiv), THFR SAr11 examples,83-97%+R SH Ar2I+BF4-c)R = aryl, alkyl21  a revolution in the pharmaceutical world due to its ability to modulate physical properties and pharmacokinetics.  Approximately 25% of current drug candidates contain at least one C–F bond, although element 9 is extremely rare among natural products.68  Fluorine finds a particular importance for positron emission tomography (PET), a functional imaging method which relies on the detection of gamma-rays produced by positron-emitting radionuclides, and that is regularly employed in numerous areas of medicine, from oncology to metabolic research.  [18F]-Fluorine possesses a long half-life (109.7 min), making it usable in chemical synthesis. It also decays following a positron-emitting pathway in very high proportion, and produces high resolution images due to a short positron linear range (2.3 mm). This radionuclide is produced by bombarding [18O]-enriched water with protons accelerated in a cyclotron, which produces [18F]-fluoride anions collected on an ion-exchange column.69  As most radiofluorination methods rely on the reaction of [18F]fluoride ions, electrophilic precursors of the imaging probes are required.  Hypervalent iodine species have been identified as suitable reagents for fluorination as early as 1982, where thermal decomposition of diaryliodonium tetrafluoroborate salts gave rise to aryl fluorides.70  Radiofluorination of diaryliodonium salts was pioneered by Pike and coworkers in the mid-1990s to prepare fluoroarenes (Scheme 1.15).71  No-carrier-added (NCA) [18F]-fluoride was used, meaning that the radioisotope was free from (stable) 19F.  A phase-transfer catalyst, such as Kryptofix-222 (K222), was employed to enhance the nucleophilicity of 18F– by sequestering its metallic counterion. Since then, many advances have been made to broaden the range of molecules that can be fluoridated in that manner, thanks to the advent of methods to prepare iodine(III) derivatives of functionalized arenes, as well as groups allowing for high selectivity in the transfer of a ligand from the iodonium species to [18F]-fluoride.72   22   Scheme 1.15 Radiofluorination using diaryliodonium salts  The potential of diaryliodonium salts as precursors of PET imaging agent has stimulated much research on group transfer selectivity from non-symmetrical iodonium salts to fluoride ion, in the interest of maximizing the formation of the desired imaging agent.  The general trend that emerged is that the more electron-poor aromatic substituent would be fluoridated selectively.  However, work from the DiMagno group73 showed that in certain cases, selectivity is poor and even erodes as the reaction evolves.  Through analysis of the reaction mixture, it was found that the aromatic ligands were exchanging to form new diaryliodonium species before the reductive elimination occurs, leading to an aryl iodide and an aryl fluoride (Scheme 1.16).   Scheme 1.16 DiMagno F-promoted ligand exchange on diaryliodonium species I XR2R1R1IR118FR218FR2I++and/or[18F]KF·K222NO OO ONK222 =OOI FOMeMe3N+F-MeCN or PhHI FOMeMeO+I FOMeF I+I Fdoes not undergo reductive elimination23  This process is related to the aryl transfer to other nucleophiles and formally allows the preparation of functionalized l3-iodanes from the transfer of an aromatic group to organoiodine(I) species.  As such species are usually prepared in strong oxidative conditions (see Section 1.3.1), metathetic aryl transfer to aryl iodides has implications in the formation of precursors to functionalized molecules.  Curiously, this noteworthy observation led to no further investigations or detailed mechanistic proposals. Beringer observed that diaryliodonium salts incorporating two aryl groups of differing electronic character selectively transfer the electron-deficient aryl ligand to nucleophilic agents.74 On this basis, Ochiai75 advanced the mechanistic proposal outlined in Scheme 1.17.  First of all, non-symmetrical diaryliodonium species such as 1.15 and 1.16 may exist in two different geometries with respect to the apical / equatorial position of the aromatic groups.  Interconversion between the two forms, which for the purpose of this discussion are described as syn or anti, depending on whether the electron-deficient aryl group is oriented at 90° or 180° from the anionic ligand, may occur through a low-energy process related to the Berry pseudorotation mechanism76 initially proposed for the isomerization of trigonal bipyramidal molecules of Group    Scheme 1.17 Beringer-Ochiai mechanism for the selective aryl transfer NuPhIδ+δ-EWGEWG IPhOTfNu-EWG IPhNuPh IEWGNuEWG IPhNuBerrypseudo-rotation1.15 1.16 syn1.16 antiNuIδ+δ-EWGI EWGNu1.171.181.191.20electron-withdrawinggroupEWG =-OTf24  15 elements. Aryl groups bearing electron-withdrawing groups favor an equatorial orientation, while ligands that can readily sustain a negative charge prefer the axial position (cf. bonding model of Figure 1.1).  A complex such as 1.16 will therefore favor a syn configuration, which would then evolve toward transition state 1.17, and thence to product 1.18, while the less favorable anti form would produce 1.20 via transition state 1.19.  Not only syn-1.16 is preferred over anti-1.16, but transition state 1.17 is also less energetic than 1.19, in that the the partial negative charge on the aromatic nucleus is better stabilized by the electron-withdrawing substituent.  The reaction therefore proceeds through transition state 1.17, and product 1.18 is obtained in greater proportion.  Later computational studies provided support for this mechanistic picture. 77 25  Chapter 2: Iodonium Metathesis  2.1 Genesis of the Project The interest of diaryliodonium salts as precursors of [18F]-radiopharmaceuticals72 led us to seek new routes to such iodanes.  An intriguing possibility materialized upon recognition that aryl iodides are relatively I-nucleophilic.  For instance, peroxyacid such as mCPBA oxidize aryl iodides to iodoso-type species (Scheme 1.8, p. 15).  Evidently, the I-atom expresses nucleophilic reactivity in the course of this reaction (Scheme 2.1).   Scheme 2.1 Presumed mechanism for the acid-catalyzed oxidation of iodoarenes by mCPBA  More significantly, Yamamoto and coworkers determined that aryl iodides are effective nucleophilic catalysts in Mukaiyama-type aldol additions.78  Thus, iodoarenes mediate silyl group transfer in the course of the reaction, allowing, for instance, the conduct of a highly diastereoselective, triple aldol cascade process (Scheme 2.2).  Iodonium ion 2.5 was detected by mass spectrometry in the form of a signal corresponding to [(TMS)3Si + IPh + CH2Cl2]+, and it was postulated to arise upon nucleophilic attack of the aryl iodide on (TMS)3SiNTf2.  Ar IClOOOHmCPBAAr IOHClHO2CHClOOHOTfOH+ TfO TfOAr IOHOTf26   Scheme 2.1 Cascade aldol oligomerization catalyzed by triflimide and iodobenzene  If an aryl iodide is nucleophilic enough to accept oxygen from a peroxyacid, or a silyl group from an appropriate donor, it may well undergo I-arylation upon treatment with exceptionally electrophilic diaryliodonium salts, in which case diaryliodonium salt would become available via a novel iodonium metathesis reaction (Scheme 2.3Error! Reference source not found.).   Scheme 2.2 Proposed iodonium metathesis  If the above reaction were possible, one could access compounds suitable for the preparation of [18F]-radiopharmaceuticals through the I-arylation of an iodinated form of a drug   R1OHOSi(TMS)3 cat. Tf2NHPh-I+5.0 equivO(TMS)3SiOR1OSi(TMS)3Tf2N Si(TMS)3I–ArPhI Si(TMS)3 NTf2O(TMS)3SiOR1OSi(TMS)3Si(TMS)3OR1OSi(TMS)3OSi(TMS)3(TMS)3SiOO(TMS)3Si2.22.1 2.32.72.42.52.654-89%major diastereomer (over 70%)IAr1OTf + Ar2 I[ ? ]IAr2OTf + Ar1 IAr1 Ar127   Scheme 2.3 Preparation of radiofluorinated compounds via a hypervalent iodine precursor  (Scheme 2.3).  This could be advantageous in that many drugs contain heteroatomic functionalities that are not compatible with oxidative conditions; therefore, the elaboration of 2.8 to 2.9 via the methods described in Chapter 1 (Section 1.3.1, p. 12) is not always possible.  Practical considerations aside, iodonium metathesis chemistry embodies a novel form of reactivity, rendering it interesting at a fundamental level.   2.1.1 Background  The iodonium metathesis shown in Error! Reference source not found. was unknown at the onset of this work.  Moreover, there were reasons to believe that it may not be feasible.  Indeed, Olofsson and collaborators recorded the important observation that no aryl ligand exchange occurs upon heating a DMF solution of an aryl iodide and a diaryliodonium salt.79  On the other hand, related ligand-exchange reactions between organoiodine compounds and hypervalent iodine species had been described.  In 1980, Koser80 established that aryl iodides undergo redox metathesis with [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser's reagent; Scheme 2.4).  In 1989, Moriarty employed this interesting transformation to prepare hypervalent derivatives of iodocubane (Scheme 2.5),81 and proposed a mechanism for the process that invokes a nucleophilic attack   X = halide, sulfonate, etc.drug IXAr[18F]–drug I2.8 2.9 2.10drug 18F28   Scheme 2.4 Aryl transfer between HTIB and 1-chloro-4-iodobenzene   Scheme 2.5 The Moriarty mechanism for redox metathesis between iodocubane and HTIB  of iodocubane on free iodonium ion 2.12.  Hydroxyl ligand migration in the resulting iodonium complex 2.13, and simultaneous expulsion (reductive elimination) of iodobenzene, produces iodonium ion 2.14, which then combines with tosylate ion to afford 2.15.  It should be noted that interest in such metathetic processes may be reviving, as apparent from a recent publication.82  Clearly, the iodonium metathesis reaction suggested in Scheme 2.3 could proceed by an analogous mechanism, except that an aryl group, instead of an OH moiety, would be transferred to the incoming aryl iodide. Related to the chemistry of Scheme 2.4, of course, is DiMagno’s remarkable observation that aryl group exchange between two iodonium salts takes place in the presence of fluoride ion (Scheme 1.16, p.22).   IHO OTs+IClCH2Cl2, RT3 daysIHO OTs+IClHO I OTsPhR I I PhOHOTsR IOHOTsHO I OTsPhHO I OTsR2.112.12 2.13 2.14 2.15I=   R–I29      2.2 Iodonium Metathesis Reactions: Initial Studies Initial investigations on the iodonium metathesis reaction entailed refluxing a DCE solution of commercial diphenyliodonium triflate, 2.16, and an excess of 4-iodotoluene in an ordinary round-bottom flask, whereupon new iodonium species arising through metathesis were detected by mass spectrometry (ESI+).  Contrary to expectations, iodonium metathesis as per Scheme 2.3 (p. 26) is indeed possible.83 Metathesis reactions carried out in this manner suffered from a number of shortcomings (Table 2.1).  An induction period of about 3 hours was required before new iodonium triflates 2.18 and 2.19 became detectable by 1H NMR or bas mass spectrometry.  Reaction times of the order of 12-24 h were necessary to achieve significant consumption of the reactants, but then only about 15% of the theoretical mass of iodonium triflates was recovered.  Significant variability was observed in the ratios of product iodonium salts were obtained from different experiments carried out under seemingly identical conditions.  Finally, complete evaporation of the solvent was often a problem when reactions were carried out on smaller scale. Reducing the temperature to avoid complete evaporation of DCE (b.p. 84 °C) was not an option as metathesis products were not obtained below the boiling point of the solvent (see Table 2.1, entry c).   On the other hand, the solid residue of reactions that had gone dry usually contained high proportions of 2.18 and 2.19.  Because 4-iodotoluene melts around 35 °C, and is already employed in large excess in the reaction, we wondered whether metathesis could be performed 30  without an added solvent.  Heating a molten mixture of 4-iodotoluene and diphenyliodonium triflate at 120 °C (Table 2.1, entry d) did result in formation of the new iodonium salts, but the starting diphenyliodonium triflate was recovered in greater proportion.   To avoid evaporation issues altogether, several test reactions were then carried out in pressure tubes sealed with a Teflon cap.  This not only produced more consistent results, it also led to nearly complete consumption of Ph2IOTf (Table 2.1, entry e).  Also, recrystallization of the starting diaryliodonium triflates from acetonitrile/ether translated into significantly more consistent conversions, product ratios, and mass recoveries.   Table 2.1 Evaluation of conditions for diaryliodonium metathesis reaction  It was rapidly determined that only diaryliodonium triflates undergo metathesis: the corresponding tetrafluoroborates, tosylates and hexafluorophosphates do not. Furthermore, the reaction only proceeded when DCE was employed as the solvent: no metathesis was observed in +conds.aentry temp. (°C)b massrecovery (%)c2.16 2.17 2.18Ph2IOTf Me I Me I OTfPh+ Me I OTf22.19ratio 2.16:2.18:2.19d a1bcde 1201120100120120time (h)method solution (sln), RBF1sln, RBFsln, RBFneat, MW vialsln, pressure tube NR115NR6048 3115152424 –1ND–1.5 : 1.0 : 2.31.0 : 10 : 29aConditions: 0.2 M solution of Ph2IOTf (0.1 mmol, 1.0 equiv) in DCE (0.5 mL), 5 equiv of 4-iodotoluene. bOil bath temperature. cCombined recovery of diaryliodonium salts after column chromatography. dRatio calculated by 1H NMR spectroscopy of isolated mixture. NR: no reaction. ND: not determined.31  DMSO, DMF, MeCN, THF, acetone, chlorobenzene, 1,2-dichlorobenzene, CH2Cl2, and CHCl3. These observations have mechanistic implications, as detailed in Section 2.3, p. 37.  The scope of the reaction with respect to the aryl iodide was investigated by allowing Ph2IOTf to react with variously substituted iodoarenes.  Such experiments revealed that high    Table 2.2 Scope of the diaryliodonium metathesis: variation of aryl iodide with Ph2IOTf  conversions were achievable in the reaction of Ph2IOTf with electron-rich 1-iodonaphthalene and 4-iodoanisole (Table 2.2, entries a and b), indicating that these iodides, along with 4-iodotoluene (Table 2.1, entry e), are good I-nucleophiles in iodonium metathesis.  The mass recovery of the mixture of iodonium triflate products was generally fair to good (48-78%), except in the case of 1-iodonaphthalene (14%).  The poor return in iodonium for this entry, as well as the moderate amounts of bis-aryl exchange product 2.22a obtained possibly originate from the fact that the +conds.aentry massrecovery (%)b2.16 2.20 2.21Ph2IOTf Ar IAr I OTfPh+ Ar I OTf2.22ratio 2.16:2.21:2.22ctime (h)Ar a1bcdef 1-naphthyl14-MeOC6H43,4-(MeO)2C6H34-Me2NC6H44-BrC6H44-MeO2CC6H4Ar 2612512121212 1417800780 0 : 2.0 : 1.011.0 : 27 : 23––1.3 : 2.0 : 2.9–aConditions: 0.2 M solution of Ph2IOTf (0.1 mmol, 1.0 equiv) in DCE (0.5 mL), 5 equiv of Ar–I, in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 120°C. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture. NR: no reaction.32  arene ligand in this case is ortho-substituted.  Literature precedent has shown that ortho-substituted aromatic ligands on iodine(III) compounds are activated for nucleophilic attack. 84  This fact was also confirmed by analyzing the mixture resulting from metathesis between Ph2IOTf and 1-iodonaphthalene by GC-MS, whereupon 1-naphthyl triflate was detected. On the other hand, excessively electron-rich aryl iodides were poor components of iodonium metathesis reactions.  To illustrate, a DCE solution of 4-iodoveratrole or 4-iodo-N,N-dimethylaniline (Table 2.2, entries c and d) and Ph2IOTf rapid developed a deep green or blue color, leading to intractable mixtures of products.  We attribute this to interfering single electron transfer (SET) processes from the highly electron-rich iodoarenes to diphenyliodonium triflate, such SET events occurring faster than metathesis and leading to a myriad of products. Electron-deficient aryl iodides underwent metathesis with difficulty or not at all.  For example, 1-bromo-4-iodobenzene reacted to a limited extent to afford the products of aryl exchange 2.21e and 2.22e (Table 2.2, entry e), but methyl 4-iodobenzoate failed to generate any metathesis products (Table 2.2, entry f).  Evidently, the electron-poor character of these aryl iodides retards the reaction with Ph2IOTf or suppresses it altogether.  Noteworthy results were obtained upon varying the electronic properties of the hypervalent iodine reagent.  As before, the observations thus recorded have mechanistic ramifications.  First of all, it was found that highly electron-rich iodonium triflates undergo metathesis at an unusually slow rate.  Thus, the reaction of di(4-anisyl)iodonium triflate with 4-iodotoluene (0.2 M iodonium salt in DCE, 5 equiv aryl iodide, 120 °C, glass tube sealed with a Teflon screwcap) required 16 h to attain ca. 53% conversion into a 1.3:1.0 mixture (1H NMR) of diaryliodonium salts 2.26 and 2.27 (Scheme 2.7).85  A rationale for this result will be provided in Section 2.3 p. 37.  The product mixture was not isolated and so no mass recovery was calculated.  33     Scheme 2.6 Reaction between di(4-anisyl)iodonium triflate and 4-iodotoluene  Turning now to unsymmetrical l3-iodanes incorporating both an electron-poor and an electron-rich aryl ligand, we explored the metathesis of various aryl(4-nitrophenyl)iodonium triflates (Table 2.3).  These materials reacted efficiently with nucleophilic iodides: in every case, crude reaction mixtures contained only small amounts of starting iodonium salt.  Surprisingly, though, the products thus obtained resulted from transfer of the more electron-rich aryl ligand to the incoming aryl iodide: with the exception of entry h, no products arising from transfer of the 4-nitrophenyl moiety were detected either by ESI MS or 1H NMR spectrometry (Table 2.3).  This stands in sharp contrast to the arylation of other nucleophiles, wherein a significant / complete preference for the transfer of the more electron-deficient aryl group is observed (Section 1.3.2, p. 16).  Mechanistic implications of this observation are discussed in Section 2.3, p. 37.  2.23I OTfMeO2+IMe ratio 2.23 : 2.24 : 2.25         2.0  :  1.3  :  1.0DCE, 120 °C16 hI OTfMe2+I OTfMeOMe2.24 2.2534   Table 2.3 Iodonium metathesis with 4-nitrophenyl substituted diaryliodonoium salts  A brief digression is in order at this juncture. A substantial amount of di(4-anisyl)iodonium triflate was present in the product mixtures obtained from entries e and h.  As the main metathesis reaction liberates 4-iodoanisole, the iodide may subsequently undergo metathesis with the various iodonium triflates present in the medium to afford the di(4-anisyl)iodonium triflate in question.  The extent of formation of the latter, even in the presence of a large excess iodobenzene or 1-iodonaphthalene, may reflect its thermodynamic stability +conds.aentrymassrecovery (%)b2.26 2.20 2.27Ar2 IAr2 I OTfAr1+ Ar2 I OTf2.28ratio 2.26:2.27:2.28:(others)cAr2Ar2adbdcddd Ph1Ar1 651737659 1.0 : – : 13e30 : 1.0 : 1.31.0 : 60 : 351.0 : 33 : 5.9I OTfAr1O2N Ph14-MeC6H44-MeOC6H41-naphthyledfdgdhd  i1jk 4-MeOC6H41 mesityl1 4-MeC6H414-MeOC6H41-naphthyl Ph14-MeC6H44-MeOC6H41-naphthyl 601798964 2613727 1.0 : 12 : 8.2 : (1.0)f30 : 1.3 : 1.01.0 : – : 6.9e1.2 : 8.4 : 1.2 : (1.0f; 0.6g) 0 : 1.0 : 7.0f30 : 1.0 : 138.4 : 1.0 : 8.4aConditions: 0.2 M solution of 2.26 (0.1 mmol, 1.0 equiv) in DCE (0.5 mL), 5 equiv of Ar–I,  in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 120 °C for 12 h. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture. dReaction performed by Kasahara, T. e2.27 and 2.28 are identical. fDi(4-anisyl)iodonium triflate. g(1-Naphthyl)(4-nitrophenyl)iodonium triflate.35  relative to other diarylidonium triflates, as evidenced also by its poor reactivity (Scheme 2.7 and associated discussion).   Selectivity for the transfer of the more electron-rich aryl ligand was retained even in the case of (mesityl)4-nitrophenyliodonium triflate (Table 2.3, entries i-k).  This is contrary to the reactivity pattern normally observed with (mesityl)aryliodonium triflates, which tend to transfer the aryl, not the mesityl, group to incoming nucleophiles.84  As briefly mentioned previously, ortho-substituted arene ligands of diaryliodonium reagents generally are the site of attack from external nucleophiles.  This so-called ortho-effect was investigated by Pike84e in the context of radiofluorination of ortho-substituted diaryliodonium salts, and his conclusion was that the selectivity observed was arising from the system adhering to the Curtin-Hammett principle.  Reductive elimination leading to coupling of the entering nucleophile with the ortho-substituted arene (product 2.31, Scheme 2.7) occurs through transition state 2.30, of lower free energy than transition state 2.32.    Scheme 2.7 Possible mechanistic pathways with unsymmetrical ortho-substituted diaryliodonium salt  IPhNuRIPhRNuBerry pseudo-rotationfastRNu Ph IRI+Ph Nureductiveelimination+NuPhIδ+δ-RNuIδ+δ-Rreductiveelimination2.29 syn 2.29 anti2.322.302.312.3336  However, in the metathesis process, the ortho-effect would not be a sufficient driving force to lead to the incorporation of the nitrophenyl ring in products, as the selectivity of the arene transfer in this case relies upon the electronic properties of the aryl groups, a discussion which will be deepened in Section 2.3, p. 37.  The ortho-effect may be invoked to account for the formation of higher proportions of the double exchange product 2.30 during the reaction between (mesityl)4-nitrophenyliodonium triflate and aryl iodides (Table 2.3, entries i-k). More surprising still was the behavior of (aryl)(2-thienyliodonium) triflates. A five-membered ring heterocycle incorporating a single heteroatom, such thiophene, is regarded as electron-rich.  For instance, it undergoes electrophilic aromatic substitution considerably faster than benzene.  According to the foregoing, an (aryl)(2-thienyliodonium) triflate should then transfer the thienyl group selectively, especially if the aryl ligand were electron-deficient.  However, a former undergraduate member of our group, Y. J. Jang, discovered that (4-carbomethoxyphenyl)(2-thienyliodonium)triflate 2.34 undergoes metathesis with virtually exclusive transfer of the 4-carbomethoxyphenyl moiety (Table 2.4): only traces of diaryliodonium products incorporating 2-thienyl groups were detected by 1H NMR spectrometry.  While (aryl)(2-thienyliodonium) salts are known to transfer the aryl group selectively to external nucleophiles,86 attributing this to electronic factors instantly creates a logical conflict with the data in Table 2.3, unless iodonium triflates 2.26 and 2.34 undergo metathesis by two different mechanisms.  This seemed extremely unlikely.  37   Table 2.4 Iodonium metathesis reaction with (4-carbomethoxyphenyl)(2-thienyl)iodonium triflate  Clearly, the notion that iodonium metathesis reactions proceed with selective transfer of the "more electron-rich aryl ligand" is overly simplistic: we thus sought a unifying mechanistic picture that would account for most or all aspects of the newly discovered iodonium metathesis reaction and resolve the contradictions inherent to the Beringer-Ochiai pathway.  2.3 Mechanistic Aspects of the Iodonium Metathesis Reaction The general mechanism of iodonium metathesis shown in Scheme 2.8 retraces the Moriarty proposal for redox metathesis (Scheme 2.5, p. 28), it reflects key themes addressed Section 2.1, and it seems to account for the failure of reactions performed in alternative, Lewis basic, solvents.  The fact that the reaction occurs only above 80-100 °C is consistent with a requirement for appropriately high temperatures to promote the obligatory dissociation of the MeO2C IOTfS+conds.a2.20 2.35Ar II OTfAr+ Ar I OTf2.36Ar2.34MeO2Centrymassrecovery (%)bratio 2.34:2.35:2.36cadbdcddd 401669138 0 : 1.0 : 15.130 : 1.0 : 7.0tr : 1.3 : 1.0tr : 1.0 : 4.1 Ph14-MeC6H44-MeOC6H41-naphthylaConditions: 0.2 M solution of 2.34 (0.1 mmol, 1.0 equiv) in DCE (0.5 mL), 5 equiv of Ar–I, in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 120 °C for 12 h. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture; traces of new 2-thienyl substituted diaryliodonium triflate salts detected for all entries. dReaction performed by Jang, Y. J.Ar38  starting 2.37 and generate a sufficiently high concentration of iodonium ion 2.38 to sustain a reasonable reaction rate; hence the failure of the reaction in low-boiling CH2Cl2 and CHCl3.  While polar, higher-boiling donor solvents such as DMSO, DMF, MeCN, THF, TFE, HFIP, and acetone are likely to facilitate dissociation, they would also strongly solvate the resultant iodine(III) cation, perhaps even bind to it, retarding the nucleophilic attack of the aryl iodide on 2.38; i.e., the rate of formation of intermediates 2.39-2.40.  This may be why Olofsson and collaborators detected no aryl ligand exchange upon heating an aryl iodide and a diaryliodonium salt in DMF.87     Scheme 2.8 General mechanism postulated for the iodonium metathesis reaction  The same mechanism could account for aryl group transfer selectivity, if a solid rationale were to be found for the preferential evolution of rapidly equilibrating (Berry pseudorotation) 2.39-2.40 toward transition states 2.41 or 2.45, leading, respectively, to products 2.43 or 2.47.  Pondering which product would form preferentially is akin to asking whether 2.39-2.40 would Ar1 IAr2OTf2.37Ar1 IAr2OTf2.38Ar3IAr1 IAr2I Ar3OTf2.392.39 / 2.40Ar1 IAr2IAr3Ar1 IAr2IAr3Ar3IAr2OTfOTf– I–Ar2– I–Ar1Ar3IAr1Ar2 IAr1I Ar3OTffastthen:2.40OTfOTfAr3IAr2Ar3IAr1OTfOTf2.41 2.42 2.432.45 2.46 2.4739  undergo faster reductive elimination of Ar1–I or Ar2–I, with the proviso that whatever reason might be ventured for a faster departure of one aryl iodide over the other must be independent of the electron-rich or electron-deficient nature of the aromatic nucleus. A possibility was envisioned as follows.  It is established that sp2-hybridized carbon is appreciably more electronegative than sp3 carbon (2.75 vs. 2.53 on the Pauling scale)88 and slightly more electronegative that iodine (2.66).89 As a consequence, the electrostatic dipole in an sp2-C–I bond is directed toward carbon; i.e., iodine is the positive end of the dipole.  This fact is central to the considerable volume of research on halogen bonding recorded in the recent literature.90 A factor that could promote preferential reductive elimination of one aryl iodide from complexes 2.39-2.40 could then be a greater extent of positive charge on its iodine atom, relative to the other aryl iodide.  Indeed, the more I-positive aryl iodide would be more readily inclined to depart from 2.39-2.40 by taking with it a pair of electrons; i.e., by a reductive elimination mechanism.  A slightly different interpretation would have it that all I-atoms in 2.39-2.40 are electron deficient and sustain a significant fraction of positive charge as a consequence of hypervalency (Figure 1.1 and relative discussion).  Accumulation of additional (+)-charge on already positively polarized I-atoms creates an energetically unfavorable situation that can be alleviated through reductive elimination of the more I-positive aryl iodide from 2.39-2.40. It is unobvious how one could experimentally measure the fractional (+)-charge on the I-atom in an aryl iodide, but an estimate can be generated by computational means.  In our laboratory, we routinely use semiempirical methods such as MNDO, MNDO/d, AM1 and PM3.  Estimates of fractional charges on individual atoms of a molecule generated by these techniques are certainly rather crude, but they would still provide support for our mechanistic surmise, if a trend consistent the foregoing hypothesis were to emerge. 40  Computational investigations91 started with the optimization of the geometry of an aryl iodide by one of the four semiempirical methods listed above.  The fractional (+)-charge on the I-atom was then calculated for the energy-minimized structure by the same semiempirical method.  The same aryl iodide was then computational analyzed, in the same manner, using the other three semiempirical methods.  The four values thus estimated for the I-(+) charge on that aryl iodide were assumed to be distributed randomly around the "true" value of the I-(+)-charge.  The latter was then estimated as the geometric mean of the four computed values, and this because a geometric mean is better than alternative averages as a reflection of the "true" value (the "actual" I-(+)-charge) toward which various mesurements (the calculated charges) tend.92 The computational algorithm is visually depicted in Figure 2.1.   Figure 2.1 Algorithm for the semi-empirical calculations of the charge on the I-atom of aryl iodides  Ar–Igeometryoptimizationbysemiempiricalmethod 1geom. optim.Ar–IcalculateI-(+)-charge bysemiempiricalmethod 1value 1geometryoptimizationbysemiempiricalmethod 2geom. optim.Ar–IcalculateI-(+)-charge bysemiempiricalmethod 2value 2geometryoptimizationbysemiempiricalmethod 3geom. optim.Ar–IcalculateI-(+)-charge bysemiempiricalmethod 3value 3geometryoptimizationbysemiempiricalmethod 4geom. optim.Ar–IcalculateI-(+)-charge bysemiempiricalmethod 4value 4geom. avg.of values1 - 4I-(+)-chargein Ar–I41  Fractional charges on the I-atom thus calculated for a number of aryl iodides are included in Appendix A (p. 81).  Analysis of these data revealed that values estimated by MNDO/d are in excellent agreement with he geometric mean.  The work described below thus relied on I-(+)-charges estimated only by the latter method. Figure 2.2 lists the fractional I-(+) charge, in units of e (the absolute value of the electron charge), for a range of aryl iodides relevant to the present work.  Compounds such as 4-iodotoluene, 4-iodoanisole, 1-iodonaphthalene, and iodobenzene exhibit a small (< +0.080 e) partial charge on the iodine atom.  One would infer that these molecules should be better I-nucleophiles / poorer I-nucleofuges than aryl iodides with progressively larger I-(+) charges. Indeed, all four aryl iodides readily undergo metathesis with diverse diaryiodonium triflates.  For that reason, we describe these as good I-nucleophiles.  Compounds sustaining an I-(+) charge between +0.080 and +0.100 e undergo metathesis with difficulty or not at all, and may thus be labeled as "unreactive" aryl iodides.  Finally, those with I-(+) charges greater than +0.100 behave predominantly as I-nucleofuges. One interesting case in that respect is 2-iodothiophene, for which calculations predict an unusually large I-(+)-charge; i.e., and exceptionally pronounced nucleofugal character.  This seems to account for the aryl transfer selectivities summarized in Tables 2.3 and 2.4.   42   Figure 2.2 Calculated values of charge on the iodine atom  In light of the above, one may venture that iodonium metathesis reactions tend to proceed in such a way that a more nucleophilic, less I-positive aryl iodide displaces a more nucleofugal, more I-positive one, or, equivalently, a less I-positive l3-iodane results at the expenses of a more I-positive one.  This principle appears to account for the aryl transfer selectivities summarized in Tables 2.1-2.4.  Moreover, it leads to the prediction that aryl iodides that are unreactive toward, e.g., Ph2IOTf, should be able to undergo metathesis with an iodane carrying a highly nucleofugal group; for instance, one based on 2-iodothiophene.  The next phase of our research addressed this surmise by focusing on possible metathesis reactions between (2-thienyl)iodonium triflates and less I-nucleophilic aryl iodides.    I I IMeIOMeIIClIIIBrIFICO2MeE EI ICF3INO2SIMeN NMeOOIE = CO2Me+0.060 +0.067 +0.075 +0.076 +0.077+0.089 +0.091 +0.091 +0.091 +0.095+0.107 +0.108 +0.118 +0.154+0.148high I-nucleophilicityhigh I-nucleofugality43  2.4 Iodonium Metathesis with Unreactive Aryl Iodides Di(2-thienyl)iodonium triflate (Th2IOTf) is an attractive substrate for iodonium metathesis as it poses no aryl-transfer selectivity issues, thus simplifying the analysis of crude reactions mixtures (see Section 2.2, p. 29).  An initial challenge in the use of this l3-iodane in metathesis was the development of a reliable gram-scale synthesis.  The compound was first prepared by Stang by reaction of di(cyano)iodonium triflate with 2-tributylstannyl thiophene (Scheme 2.9).93  Although the procedure is efficient, both reagents pose serious health and safety hazards, especially so toxic di(cyano)iodonium triflate, which must be kept cold and under an inert atmosphere, as it degrades violently at room temperature.93   Scheme 2.9 Stang's preparation of di(2-thienyl)iodonium triflate  To avoid the use of di(cyano)iodonium triflate, we explored the preparation of di(2-thienyl)iodonium triflate from molecular iodine, mCPBA, and thiophene by the Olofsson method (see Scheme 1.8, method b, p. 15).  We note that Olofsson had detailed the preparation of di(2-thienyl)iodonium tosylate by this procedure, but not the anion exchange to produce Th2IOTf.  We found that in situ treatment of the di(2-thienyl)iodonium tosylate with triflic acid produced only black, insoluble solids, but successful anion exchange was achieved as follows.  First, the crude tosylate salt was thoroughly purified by elution through basic alumina to remove excess tosic acid, then recrystallization from acetone/diethyl ether.  Treatment of the pure tosylate salt with excess triflic acid at -40 °C and purification of the resultant triflate salt also by elution NC ICNOTf + 2S SnBu3CH2Cl2-40°C–20 °C76%I OTfSS44  through basic alumina and recrystallization from acetone/diethyl ether afforded the desired product in moderate overall yield (Scheme 2.10).     Scheme 2.10 Preparation of di(2-thienyl)iodonium triflate by Olofsson-type methodology   The thermal stability of di(2-thienyl)iodonium triflate was first verified by heating in DCE solution at 120 °C: the temperature previously employed for iodonium metathesis.  Complete degradation was observed within 5.5 h, resulting in a dark purple solution containing large amounts of insoluble solids.  Consequently, subsequent attempts at iodonium metathesis with Th2IOTf were performed at reduced temperatures. As anticipated on the basis of the foregoing, heating a solution containing both 4-iodotoluene and Th2IOTf in DCE at 80 °C for 48 h resulted in conversion of 72% of the dithienyliodonium triflate in the metathesis products, with the fruit of single arene displacement being the major component of the mixture (see Scheme 2.11).  The reaction rate is evidently slower than analogous reactions with different iodine(III) reagents, although we would expect the 2-iodothienyl groups to have powerful nucleofugal capability.  We presume that this observation arises from the increased accumulation of positive charge on the iodine atom of Th2IOTf causing more difficult ion pair separation (first step of the proposed iodonium metathesis mechanism, see Scheme 2.8, p. 38) as the electrostatic attraction between the triflate anion and the diaryliodonium cation would be stronger. + 2S HI2mCPBA (3 equiv)TsOH (3 equiv)CH2Cl2, 15 hTfOH (2 equiv)CH2Cl2, -40 °CI OTsSSI OTfSS51%(Olofsson: 66-68%)75%(37% over two steps)45    Scheme 2.11 Reaction between dithienyliodonium triflate and 4-iodotoluene  More significantly, Th2IOTf did in fact undergo metathesis with unreactive aryl iodides, albeit at a substantially slower rate. Results of key experiments are presented in Table 2.5, wherein the iodoarenes are arranged in order of increasing I-positive character (see Figure 2.2,   p. 42).  Reactions employing moderately I-positive iodoarenes were allowed to proceed for 48 h (Table 2.5, entries a-d), whereupon the mixture of diaryliodonium triflates obtained after column chromatography contained between 16% and 66% of starting iodane.  The higher proportion of Th2IOTf was recovered in the metathesis with methyl 4-iodobenzoate (Table 2.5, entry d), a predictable result as this aryl iodide possesses a higher I-(+)-charge compared to the 4-halo-1-iodobenzene derivatives (see figure 2.1).  Reaction times had to be shortened with even more I-positive aryl iodides (Table 2.5, entries e-g) to ensure recovery of product l3-iodanes.  If the reactions were left to run for 24 h, no iodonium triflates were detected in the crude mixture, due to the thermal instability of the products.  Unfortunately, shortened reaction times translated into very low conversions, especially in the case of 4-iodobenzotrifluoride (entry f) and 1-iodo-4-nitrobenzene (entry g), but the fact that metathesis did occur seemed to provide support for our mechanistic hypothesis.  DCE, 80 °C, 48 h 68% mass recovery+2IOTf2.48 2.492.50ISIMeMeSISMeratio 2.48 : 2.49 : 2.50         1.5  :  2.8  :  1.0OTfOTf46   Table 2.5 Metathesis of unreactive aryl iodides with di(2-thienyl)iodonium triflate under thermal conditions  Our mechanistic interpretation also led to the surmise that the thermal instability of the iodanes shown in Table 2.5 may be due to the excessively positive character of the iodine atom, which could promote decomposition into an aryl iodide and an aryl triflate, as important amounts of iodothiophene, 2-thienyltriflate and 4-nitrophenyl triflate were detected by GC-MS analysis of the mixture resulting from heating 2.48 with 4-nitro-1-iodobenzene for 24 h.  Therefore, we turned our attention to metathesis reactions between unreactive aryl iodides and phenyl(2-thienyl)iodonium triflate (Ph(Th)IOTf), which still incorporates a significantly I-positive, nucleofugal 2-iodothiophene, but also a modestly I-positive iodobenzene.  The extent of positive character on the iodine atom of this compound should then be lower than in Th2IOTf, and this should translate into greater thermal stability.  Furthermore, the desired iodane is prepared easily +conds.aentry massrecovery (%)b2.482.202.51Ar I I OTfAr+Ar I OTf2.52ratio 2.48:2.51:2.52ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 481244848121212 611608258879589 7.4 : 6.3 : 1.011.2 : 2.8 : 1.01.0 : 3.2 : 2.21.9 : 1.0 : 024 : 8.3 : 1.0>50 : 1.0 : 017 : 1.0 : 0aConditions: 0.1 M solution of 2.48 (0.2 mmol, 1.0 equiv) in DCE (2 mL), 5 equiv of Ar–I, in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 80 °C. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture.I OTfSS S47  by the Olofsson method, and the anticipated selectivity of aryl transfer (preferential transfer of phenyl / expulsion of 2-iodothiophene) would provide additional support for our mechanistic proposal (Scheme 2.8, p. 38).  Phenyl(2-thienyl)iodonium triflate was indeed significantly more thermally stable than Th2IOTf.  Upon heating in DCE solution at 110 °C, it underwent decomposition into Ph–I,      Ph–OTf, and 2-iodothiophene, as determined by GC-MS, with a half-life of approximately 8 h at 110 °C.  This was a considerable improvement over the rapid thermolysis of the di(2-thienyl)iodonium triflate, but still meant that reduced temperatures would likely be preferable for metathesis.  The fact that no signals attributable to 2-thienyl triflate were apparent in the gas chromatogram suggested that selective reductive elimination of 2-iodothiophene was preferred even for the decomposition of the diaryliodonium salt itself, in line with the hypothesis (Section 2.3, p. 37) that the more I-positive aryl iodide acts as the nucleofuge, while the aryl group of the less I-positive aryl iodide (in this case, the phenyl) is transferred to the nucleophile (triflate ion). Iodonium metathesis between phenyl(2-thienyl)iodonium triflate and unreactive aryl iodides was carried out in DCE solutions at 80 °C and it was successful in all cases (Table 2.6).  Mass recoveries of iodine(III) species after column chromatography were significantly better than in the previous case; however, the mixtures were more complex than anticipated due to the presence of varying amounts of diphenyliodonium triflate.  This by-product is likely to result by metathesis of iodobenzene liberated during thermal decomposition of Ph(Th)IOTf with the various diaryliodonium triflates present in solution.  The molar ratio of the various iodanes thus produced was more difficult to determine by 1H NMR spectrometry than in previous cases, due to signal overlap.  Therefore, quantitative 13C NMR spectrometry94 was used as a supplement to 1H NMR data (see Appendix B for details on the calculations made). 48   Table 2.6 Metathesis of unreactive aryl iodides with phenyl(2-thienyl)iodonium triflate under thermal conditions  In all cases, the diaryliodonium triflate mixtures obtained from metathesis of phenyl(2-thienyl)iodonium triflate with I-positive iodoarenes contained lower proportions of starting iodane than the corresponding reactions with Th2IOTf.  Furthermore, the dominant or exclusive product was that of displacement of 2-iodothiophene, as predicted.  The formation of metathesis products incorporating the 2-thienyl group 2.55 was only detected in quantifiable amounts with the more I-nucleophilic 1-chloro-4-iodobenzene (Table 2.6, entry a).  Worthy of note is the formation of a product of double metathesis, 2.52, in entries a-b and d-e.  It is not clear at this time whether 2.52 result solely upon reaction of 2.20 with 2.51 (selective displacement of 2-iodothiophene) or also by other pathways. +conds.aentry massrecovery (%)b2.532.202.51Ar I I OTfAr+ Ar I OTf2.52ratio 2.53:2.54:2.51:2.52:2.16ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 241242424121212 791799681639289 2.2 : 11 : 1.5 : 3.6: 1.013.8 : 12 : 0 : 4.1 : 1.07.4 : 1.0 : 0 : 0 : 043 : 29 : trd : 2.0 : 1.09.8 : 7.0 : 0 : 1.0 : 1.112 : 1.0 : 0 : trd : trd3.3 : 1.0 : 0 : trd : trdaConditions: 0.1 M solution of 2.53 (0.2 mmol, 1.0 equiv) in DCE (2 mL), 5 equiv of Ar–I, in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 80 °C. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H and quantitative 13C NMR spectroscopy of isolated mixture. dMass detected by ESI-MS, but compound not identified by 1H NMR spectroscopy.Ph I OTfS SPh I OTfAr+2.54+Ph I OTfPh2.1649  The above notwithstanding, the proportions of metathesis products in mixtures obtained from reactions with the more I-positive iodoarenes with either Th2IOTf or Ph(Th)IOTf remained low.  It is established that thermal activation in the form of microwave heating can accelerate numerous organic reactions,95 including those involving diaryliodonium salts.96  We thus turned to microwave heating in an effort to achieve better conversions over a shorter time, while simultaneously lessening degradation of both starting material and products. Microwave irradiation indeed resulted in higher conversion of di(2-thienyl)iodonium triflate into metathesis products within only 2-4 h (Table 2.7) instead of the previously required 12-48 h (Table 2.5).  Especially noteworthy was the rate increase observed with the more electron-deficient aryl iodides (Table 2.7, entries f and g).  However, increased conversions over    Table 2.7 Metathesis of unreactive aryl iodides with di(2-thienyl)iodonium triflate with microwave irradiation +conds.aentry massrecovery (%)b2.482.202.51Ar I I OTfAr+Ar I OTf2.52ratio 2.48:2.51:2.52ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 41443222 921565536546871 13.3 : 7.1 : 1.011.0 : 1.3 : 1.30 : 1.3 : 1.31.5 : 1.0 : 3.32.5 : 1.9 : 1.06.5 : 3.5 : 1.02.6 : 1.0 : 0aConditions: 0.1 M solution of 2.48 (0.3 mmol, 1.0 equiv) in DCE (3 mL), 5 equiv of Ar–I, in microwave vial sealed with a metal crimp-cap, microwave irradiation (Biotage® Initiator at 100 °C in high absorption mode). bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture.I OTfSS S50  shorter reaction times did not translate into improved mass recovery.  To the contrary, generally diminished quantities of iodine(III) species were recovered relative to reactions performed with an oil bath (compare to Table 2.5).  Evidently, diaryliodonium salts are more succeptible to degradation upon microwave irradiation. Similar results were observed for reactions of phenyl(2-thienyl)iodonium triflate under analogous conditions (Table 2.8).  For example, the product mixture isolated from the reaction with 4-nitro-1-iodobenzene (Table 2.8, entry f) contained 67% of metathesis products, as opposed to only 8% for the same reaction carried out with conventional heating (Table 2.6, entry f).  On the other hand, mass recoveries were of the order of only about 30-40% of the theoretical, with the exception of entry c (70% mass recovery).     Table 2.8 Metathesis of unreactive aryl iodides with phenyl(2-thienyl)iodonium triflate with microwave irradiation +conds.aentry massrecovery (%)b2.532.202.51Ar I I OTfAr+ Ar I OTf2.52ratio 2.53:2.54:2.51:2.52:2.16ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 41444222 331407030214029 trd : 5.0 : trd : 6.2: 1.011.7 : 6.2 : 0 : 6.5 : 1.04.3 : 9.8 : 0 : 1.0 : 01.5 : 4.8 : 1.0 : 2.0 : 1.23.8 : 4.0 : 1.8 : 1.0 : 1.23.8 : 4.1 : 1.3 : 1.0 : 1.25.4 : 1.4 : trd : 0 : 1.0Ph I OTfS SPh I OTfAr+2.54+Ph I OTfPh2.16aConditions: 0.1 M solution of 2.53 (0.3 mmol, 1.0 equiv) in DCE (3 mL), 5 equiv of Ar–I, in microwave vial sealed with a metal crimp-cap, microwave irradiation (Biotage® Initiator at 100 °C in high absorption mode). bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H and quantitative 13C NMR spectroscopy of isolated mixture. dMass detected by ESI-MS, but compound not identified by 1H NMR spectroscopy.51  An additional complication in this case was also some erosion of aryl group transfer selectivity.  Thus, iodane 2.51 in entries d-f of Table 2.8 was formed to a greater extent than before (compare to Table 2.6).  Loss of selectivity may be due to local overheating in the microwave field, but a sounder rationale must await the results of additional investigations. In summary, this work provides support for the hypothesis that iodonium metathesis reactions proceed so that a less I-positive aryl iodide displaces a more I-positive one from the starting diaryiodonium triflate.  Metathesis reactions with more I-positive, less I-nucleophilic aryl iodides are possible with both di(2-thienyl)iodonium triflate and phenyl(2-thienyl)iodonium triflate.  Conversion into new diaryliodonium salts is limited by the thermal degradation of all iodine(III) species during the reaction.  When conventional heating is applied, this appears to be due primarily to the extended reaction times that are required to achieve measurable conversions.  Microwave heating results in faster reaction rates, but also in faster degradation of the various iodanes, and, in the case of phenyl(2-thienyl)iodonium triflate, diminished aryl group transfer selectivity, at least in some cases. The experiments discussed thus far were designed to clarify how electronic factors affect aryl group transfer selectivity in iodonium metathesis reaction.  However, steric effects are also known to influence aryl group transfer preference from a diaryliodonium salt to an external nucleophile.Error! Bookmark not defined.,97  To illustrate, (mesityl)phenyliodonium triflate selectively transfers the phenyl ligand.  This is attributable to the ortho-effect detailed in Section 2.2 (p. 35), which causes reductive elimination of ortho-substituted diaryliodonium salts to occur with selective transfer of the arene bearing the substituent to the nucleophile.84  (Mesityl)phenyliodonium triflate was thus employed to ascertain whether release of steric 52  compression might provide a sufficiently powerful driving force to promote iodonium metathesis with poorly I-nucleophilic aryl iodides.  Only the moderately I-positive 4-halo-1-iodobenzenes underwent metathesis with (mesityl)phenyliodonium triflate upon heating in DCE solution in an oil bath, and in each case only phenyl group transfer was observed (Table 2.9, entries a-c), but conversions were much lower than for thiophene-substituted diarylidonium salts.  Significantly more I-positive aryl iodides (entries d-g) failed to react.  Once again, microwave irradiation promoted marginally increased conversions (Table 2.10, entries a-c), but more I-positive aryl iodides still did not lead to the production of metathesis products (Table 2.10, entries d-g).  In all cases, reactions of (mesityl)phenyliodonium triflate afforded generally higher mass recoveries compared to those of thiophene-substituted diaryliodonium triflates, supporting the notion that higher positive character on the iodine(III) center promotes thermal degradation of diaryliodonium salts.  53   Table 2.9 Metathesis of unreactive aryl iodides with (mesityl)phenyliodonium triflate under thermal conditions The results of these experiments suggest that steric effects may be harnessed to overcome the poor reactivity of poorly nucleophilic aryl iodides, but only if the latter are slightly more I-positive than the nucleofuge. Thus, the 4-halo-iodobenzenes, in which the estimated (MNDO/d) I-(+)-charge is about 0.090 e, displaced iodomesitylene, I-(+)-charge equal to ca. 0.060.  However, more I-positive iodides did not react.  This may imply that sterics can override unfavorable changes in the I-(+)-character of the reactants corresponding to at most 0.030 e.  While additional experiments are needed to verify this surmise, it is apparent that all results yet obtained are in accord with our mechanistic hypothesis and underscore the importance of electronic effects.  +conds.aentry massrecovery (%)b2.552.202.54Ar I Ph I OTfAr+Ar I OTf2.52ratio 2.55:2.54:2.52ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 241242424242424 8318084NRNRNRNR 17 : 1.0 : 0117 : 1.0 : 029 : 1.0 : 0––––aConditions: 0.1 M solution of 2.55 (0.3 mmol, 1.0 equiv) in DCE (2 mL), 5 equiv of Ar–I, in thick-walled glass tube sealed with a Teflon screwcap and immersed in an oil bath maintained at 100 °C. bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture.  NR: No reaction.IPhOTf54   Table 2.10 Metathesis of unreactive aryl iodides with (mesityl)phenyliodonium triflate with microwave irradiation  2.5 Conclusions and Future Direction In summary, an unprecedented aryl group transfer from a diaryliodonium triflate to an aryl iodide has been demonstrated.  The new process is described as the iodonium metathesis reaction, and it occurs upon heating a mixture of the reactants above 80-100 °C in a polar, aprotic, poorly Lewis basic solvent such as DCE. Thermal activation may be provided in the form of conventional heating (oil bath) or microwave irradiation.  In the latter case, metathesis rates become much faster, but so do the rates of decomposition of the various iodanes, resulting in diminished mass recoveries – at least when the I-nucleophile is a particularly electron-deficient iodoarene.  In some cases, erosion of aryl group transfer selectivity was also observed.   +conds.aentry massrecovery (%)b2.552.202.54Ar I Ph I OTfAr+Ar I OTf2.52ratio 2.55:2.54:2.52ctime (h)Ar a1bcdefg 4-ClC6H414-BrC6H44-FC6H44-MeO2CC6H43,5-(MeO2C)2C6H34-CF3C6H44-NO2C6H4Ar 10110106666 8317982NRNRNRNR 11 : 1.0 : 0133 : 5.7 : 1.05.4 : 1.0 : 0––––aConditions: 0.1 M solution of 2.55 (0.3 mmol, 1.0 equiv) in DCE (3 mL), 5 equiv of Ar–I,in microwave vial sealed with a metal crimp-cap, microwave irradiation (Biotage® Initiator at 100 °C in high absorption mode). bCombined recovery of diaryliodonium salts after column chromatography. cRatio calculated by 1H NMR spectroscopy of isolated mixture. NR: No reaction.IPhOTf55  Aryl transfer selectivity studies revealed inconsistencies with previous reactivity models.  A mechanistic proposal that accounts for the observed preferences was formulated on the basis of the extent of partial positive charge present on the iodine atom of the incoming (nucleophile) and departing (nucleofuge) aryl iodide, such charges being readily (if crudely) estimated by MNDO/d.  A trend was uncovered, suggesting that iodonium metathesis reactions tend to occur so that a less I-positive, more I-nucleophilic aryl iodide displaces a more I-positive, more I-nucleofugal one.  An unusually large I-(+)-charge, indicative of high I-nucleofugal character, was estimated for 2-iodothiophene.  Indeed, diaryliodonium triflates incorporating a thienyl group underwent metathesis even with aryl iodides that had failed to react with iodanes based on less I-positive, less nucleofugal aryl iodides.  Moreover, all these reeactions proceeded with selective substitution of 2-iodothiophene. Steric effects can promote the normally unfavorable substitution of an aryl iodide with a slightly more I-positive one, but seemingly only if the I-(+)-charges of nucleophile and nucleofuge differ by no more than about 0.030 e. Work currently is currently underway to elucidate aspects of iodonium metathesis that require clarification, and to explore possible applications of the technique.  A possibility in that regard is the use of the method to prepare l3-iodanes with substitution patterns not accessible via Friedel-Crafts chemistry. For example, a symmetrical diaryliodonium triflate in which the aryl groups carry an electron-donating substituent at the meta-position would be unavailable by the methods outlined earlier (Section 1.3.1, p. 12), unless one of the aryl segments were provided as an organometallic agent (Scheme 1.9, p. 15).  In contrast, the iodonium metathesis reaction would enable the synthesis of such compounds as shown in Scheme 2.12.  56   Scheme 2.12 Preparation of meta-substituted diaryliodonium triflates via iodonium metathesis  The use of iodonium metathesis for the formation of diaryliodonium precursors of radiopharmaceutical remains to be investigated in details.  Aryl transfer to 5-iodouracil or to its derivatives, including 5-iodo-2,4-dimethoxypyrimidine (a protected form of uracil),98 has so far proven elusive (Scheme 2.13).  This is attributable to the pronounced positive character of the    Scheme 2.13 Iodonium metathesis attempts with 5-iodo-2,4-dimethoxypyrimidine  iodine atom in these molecules (ca. +0.150, Figure 2.1), as well as other factors not discussed here.  More promising are metathesis reactions of aryl iodide derivatives of particular drugs, wherein the I-(+)-charge is estimated to be small.  Radiolabeled forms of these pharmaceuticals would also be useful in current medicine.   +I OTfSSEDGII OTfEDGEDGNNOMeI ArI ArOTf+MeO NNOMeIMeOArOTf57  Chapter 3: Metal-Free Preparation of Triarylchalcogenium Salts  3.1 Background on Triarylchalcogenium Salts In the late 1970’s, scientists at the General Electric Co. determined that triarylsulfonium salts are valuable as initiators of cationic polymerization reactions.99 These processes are employed for the production of technologically important polymers such as poly(isobutylene) and polytetrahydrofuran through carbocationic mechanisms (Scheme 3.1),99 and may be initiated by the addition of an appropriate Brønsted or Lewis acid to the monomer.  This, however, creates various technical difficulties, such as rapid gelling of the mixture.     Scheme 3.1 Examples of cationic polymerization initiated by the triarylsulfonium salts  Intact sulfonium possess high thermal stability and good latency even in the presence of nucleophilic monomers,100 and can be dispersed in monomeric mixtures with no untoward consequences.  However, they generate powerful Brønsted acidic species upon irradiation; i.e., they behave as photoacid initiators.  Thus, cationic polymerization starts only when the mixture is exposed to UV light of appropriate wavelength, and can even be performed with multifunctional monomers without solvent, greatly reducing costs and energy required for the Ar3S+X-hυsolv-HAr2S + H X Ar H+ Ar Ar+H XO OHHpropagationnHOO HnO58  production of the desired materials.99 The dispersal of a sulfonium salt in the monomer prior to curing is especially advantageous in applications requiring rapidity and precision, such as coatings, printing inks, and photolithography.99  The mechanism of photoacid generation (Scheme 3.2) is believed to involve homolysis leading to a diarylsulfinium radical cation 3.2, accompanied by counterion X–, along with an aryl radical 3.3.99, 101 Hydrogen atom transfer from the solvent to 3.2 affords a diaryl sulfinium, 3.5: a powerful Brønsted acid that readily initiates cationic polymerization of the monomer.    Scheme 3.2 Photolysis of triarylsulfonium salts  3.2 Arylation of Chalcogenides102 Crivello’s influential 1978 paper (see Section 1.3.2, p. 19)59 seemingly engendered the tacitly accepted notion that copper catalysts are necessary for the preparation of sulfonium salts from diaryl sulfides and diaryliodonium salts.  Our discovery that aryl iodides are sufficiently nucleophilic to undergo iodonium metathesis suggested otherwise.  Indeed, the sulfur atom in a diaryl sulfide would be expected to be even more nucleophilic than the iodine atom of an aryl iodide. If an aryl iodide 3.9 is arylated by an iodonium ion such as 3.10, a diaryl sulfide 3.14 should undergo the same reaction even more readily, leading to triarylsulfonium triflate 3.16 upon reductive elimination (Scheme 3.3). Ar3S+ X-hυAr2S+ + Ar + X-3.1 3.2 3.3 3.4solv-HAr2S+ H3.5+ solv3.6Ar2S H++3.7 3.859    Scheme 3.3 Comparison of mechanisms of iodonium metathesis with sulfide arylation by diaryliodonium salts  Evidence that arylation of sulfides should occur without the intervention of a metal catalyst already exists in the literature.  It is known that prolonged heating of a mixture of diphenyliodonium tetrafluoroborate and diphenyl sulfide induces formation of Ph3SBF4, albeit in moderate yield.103  There are therefore opportunities for developing a metal-free route to triarylsulfonium salts with performances similar to Crivello’s methodology.  Such a preparation would translate into lower costs and simpler purification: distinct advantages given the technological importance of triarylsulfonium salts.   Initial experiments aiming to probe the foregoing hypotheses retraced the techniques developed for the iodonium metathesis reaction (Section 2.3, p. 37).  Thus, a DCE solution of commercial diphenyl sulfide and diphenyliodonium triflate was heated at 120 °C in a pressure tube.  Triphenylsulfonium triflate was thus obtained in 92% yield after column chromatography (Table 3.1, entry a).   IAr2Ar2OTf+ IAr2Ar2OTfAr1 IAr2OTf+Ar1 I I Ar2IAr2Ar2OTf+ IAr2Ar2OTfAr1 SAr2OTf+Ar1 S I Ar2Ar1 Ar13.93.10 3.11 3.123.133.143.103.133.15 3.16IAr1SAr1Ar160   Table 3.1 Empirical optimization of the aryl transfer to diphenylsulfide  A screen of conditions revealed both analogies and differences between the present transformation and the iodonium metathesis reaction.  Just as in the case of iodonium metathesis, donor solvents such as THF or acetonitrile (Table 3.1, entries b and c) completely inhibited the process.  Furthermore, triphenylsulfonium species were only obtained when the triflate iodonium salt was employed for the reaction. Diphenyliodonium tetrafluoroborate and hexafluorophosphate (Table 3.1, entries d and e) failed to yield any of the desired product, while the tosylate and chloride salts (Table 3.1, entries f and g) underwent thermal decomposition. Unlike iodonium metathesis, the present reaction proceeded well in chloroform (Table 3.1, entry h; 92% yield after column chromatography).  On the other hand, dichloromethane appeared to be Ph2S Ph3S+X-conds.aentry solv. X yield of 3.19 (%) asbcdefghis DCEsTHFMeCNDCEDCEDCEDCECHCl3CH2Cl2 OTfsOTfOTf BF4 PF6OTsClOTfOTf92b0c0c0c0c0d0d92b0c3.17 3.18 3.19aConditions: 0.1 M solution of Ph2IX (1.0 equiv) in the indi-cated solvent (1 mL), 1.5 equiv of Ph2S, in a thick-walled glass tube sealed with a Teflon screwcap and heated in anoil bath at 120 °C, 15 h. bYield after column chromatographycSulfonium not detected by 1H NMR dDegradation of theiodonium salt was noted.Ph2IX+61  unsuitable as a solvent (Table 3.1, entry i; no product detected in the 1H NMR spectrum of crude reaction mixtures).  The electronic character of the aryl groups of the sulfide seemed to have only a marginal effect on the rate and efficiency of the reaction (Table 3.2).  To illustrate, comparable results were obtained in the S-arylation of sulfides incorporating rings bearing either electron-rich or electron-deficient substituents with either diphenyliodonium triflate or di(4-bromophenyl)iodonium triflate (Table 3.2).  A possible exception was di(4-bromophenyl) sulfide, which underwent arylation in slightly reduced yield (Table 3.2, entry b).   Table 3.2 Aryl transfer to sulfides using symmetrical diaryliodonium triflate salts  Diaryliodonium species bearing different groups were employed to probe the selectivity of aryl transfer to a sulfur center (Table 3.3).  It will be recalled that in the iodonium metathesis reaction aryl group transfer selectivity was pronounced, and it was dictated by the nucleofugal properties of the two possible departing aryl iodides (Section 2.3, p. 37).  In the present case, Ar1-S-Ar2 + (Ar3)2IOTf Ar1Ar2Ar3S+OTf-conds.aentry yield of 3.22b+ Ar3-IAr1 Ar2 Ar3asbcd Phs4-BrC6H44-MeOC6H4Ph Phs4-BrC6H44-MeOC6H44-NO2C6H4 4-BrC6H4s4-BrC6H4PhPh 96b7987853.20 3.21 3.22 3.23aConditions: 0.1 M solution of Ar32IOTf (1.0 equiv) in DCE (1 mL), 1.5 equivof diarylsulfide, in a thick-walled glass tube sealed with a Teflon screwcap and heated in an oil bath at 120 °C, 15 h. bYield after column chromatography.62  generally lower selectivity was observed (Table 3.3).  This is particularly noticeable for entry c, where the 4-nitrophenyl and 4-methoxyphenyl groups are transferred in nearly equal ratios.   Table 3.3 Aryl group transfer selectivity survey  A first explanation for the lack of selectivity of the aryl transfer to sulfides could come from the competition between the Beringer-Ochiai pathway with the mechanism leading to departure of the more electron-poor aryl iodide.  The former would lead to incorporation of the electron-deficient arene (see Scheme 1.17), while the latter would afford triarylsulfonium triflates including the electron-rich aromatic group.  Alternatively, the nucleophilic character of the sulfur atom in organic sulfides, the erosion of aryl group transfer selectivity may be due to a competing nucleophilic aromatic substitution (SNAr) pathway, which becomes especially significant if one of the aryl groups on the iodonium species carries an electron-withdrawing substituent.  Thus, the nitrophenyl group on iodonium triflate 3.24c could well promote Ph2S + Ar1Ar2IOTf Ph2Ar1S+OTf-conds.aentry yield of 3.25 + 3.26c+ Ph2Ar2S+OTf-Ar1 Ar2 Ratio 3.25 :  3.26basbcde 4-NO2C6H4s4-MeO2CC6H4 4-NO2C6H4s2-thienyl2-thienyl PhsPh4-MeOC6H4Ph4-MeO2CC6H4 1.0 : 2.3s1.0 : 1.91.0 : 1.31 : 3.81.0 : 3.9 98b949282853.17 3.24 3.25 3.26aConditions: 0.1 M solution of Ar1Ar22IOTf (1.0 equiv) in DCE (1 mL), 1.5 equiv of Ph2S,in a thick-walled glass tube sealed with a Teflon screwcap and heated in an oil bath at 120 °C, 15 h. bRatio calculated by 1H NMR cYield after column chromatography63  formation of the Meisenheimer complex 3.28, which would be responsible for the ultimate production of 3.29 (Scheme 3.4).   Scheme 3.4 Mechanism of the nucleophilic aromatic substitution pathway with diarylsulfides  The best aryl group transfer selectivity was observed with 2-thienyl substituted l3-iodanes (Table 3.3, entries d and e), which reacted with preferential departure of 2-iodothiophene.  This in accord with that which was postulated in Section 2.3 (p. 37): displacement of the more nucleofugal iodide drives the reaction, and as 2-iodothiophene is one of the iodides with the highest charges on the iodine atom (see table 2.1), the second group on the diaryliodonium triflate is transferred preferentially. Attempts to transpose the above results to the production of sulfonium salts containing alkyl groups were less successful.  To wit, treatment of thioanisole, 3.31 with di(4-bromophenyl) iodonium triflate gave rise to sulfonium salt 3.32, which, however, rapidly transferred the methyl group to intact thioanisole to form dimethylphenylsulfonium triflate 3.33 and diaryl sulfide 3.34 (Scheme 3.5).  After 9 h at 120 °C, diphenyliodonium triflate was fully consumed and compounds 3.32 and 3.33 were present in a ratio of 1.0:6.7.  I OTfEDGEWGArSArSNArI OTfEDGEWGSAr2IEDGEWG SAr2OTf+3.273.283.293.3064   Scheme 3.5 Arylation of thioanisole with di(4-bromophenyl)iodonium triflate   Alkyl group transfer between sulfur(IV) species and sulfides had previously been observed by Ochiai,104 who rationalized the process in terms of a more electron-rich, more nucleophilic sulfide, such as thioanisole, displacing a less electron-rich, less nucleophilic one such as 3.34.  A similar principle is apparent in the Sanford acid-catalyzed synthesis of diaryl sulfides (Scheme 3.6),63 which relies on the use of diaryliodonium trifluoroacetates.  The transformation occurs so that a proton, a methyl or a butyl group are transferred to the trifluoroacetate ion liberated in the course of the reaction.    Scheme 3.6 Sanford's acid-catalyzed synthesis of diarylsulfides  In our case, the exceedingly poor nucleophilicity of triflate ion may provide thioanisole the opportunity to act as the nucleophile.  However, some degree of methyl group transfer to triflate ion does occur, as a resonance attributable to methyl triflate (d = 4.22 ppm) appeared in the 1H NMR spectrum of crude reaction mixtures after 9 h.  The presence of MeOTf was even SMe I OTfBrBr+CDCl3120 °CSPh MeBrOTfPhSMe Ph SMeMeOTf+SPhBr3.313.21a3.323.333.34ratio 3.32 : 3.33          1.0 : 6.7            (9 h)SnBu3.35[Ph2I]+CF3COO-1,4-dioxane120 °CPhSPh nBuCF3COO3.36PhSPhCF3COOnBu+3.173.3765  more apparent in the arylation of 4-bromo-thioanisole with diphenyliodonium triflate, a slow reaction that required 31 h for complete conversion, probably due to the diminished nucleophilicity of the substrate and the lower nucleofugality of iodobenzene compared to 1-bromo-4-iodobenzene.  At the end of the reaction, (4-bromophenyl)phenyl-methylsulfonium triflate 3.32, (4-bromophenyl)dimethylsulfonium triflate 3.39, and MeOTf were present in a proportion of 1.0:9.1:1.8, as determined by 1H NMR spectroscopy (Scheme 3.7).   Scheme 3.7 Arylation of 4-bromothioanisole with diphenyliodonium triflate  The ease of arylation of diaryl sulfides induced us to explore the analogous reaction of other diaryl chalcogenides.  All attempts to O-arylate diaryl ethers leading to triaryloxonium salts failed, arguably because of the greater electronegativity of oxygen, and consequently diminished nucleophilicity, of oxygen relative to sulfur.  In a like vein, diphenyl sulfoxide failed to react with Ph2IOTf.   Perhaps of greater relevance was the arylation of heavier diaryl chalcogenides, given the interest of the resultant triaryl chalcogenium salts in current chemical technology.  Just like their sulfur congeners, triarylselenonium salts are known photochemical initiators of cationic polymerization.105  However, their higher cost relative to sulfonium salts overshadow their use. Triaryltelluronium salts show potential as useful s-donor ligands for transition metal SMeBr3.38Ph2IOTfCDCl3120 °CSPh MeBrOTf3.32SMeBr SMe2BrOTf+SPhBr3.34+ MeOTf3.393.41ratio 3.32 : 3.39 : 3.41         1.0  :  9.1  :  1.8          (31 h)66  complexes,106 and are typically prepared through the reaction of TeCl4 with a main-group arylmetallic agent,107 a method which does not allow for the preparation of telluronium salts with different arenes incorporated in its structure. Diphenylselenide reacted with diphenyliodonium triflate under the same conditions employed for the arylation of diaryl sulfides, and at comparable rates.  Complete conversion was achieved in 24 h in either DCE or chloroform to afford nearly quantitative yields of triphenylselenonium triflate (Table 3.4, entries a and b).  The latter has been prepared from the same starting material in the presence of Cu(I) catalysts, with only diaryliodonium hexafluoroarsenate salts being used successfully.59 Our finding therefore suggests an alternative with much reduced health and environmental concerns as the triflate counterion poses no issue.   Table 3.4 Catalyst-free arylation of Ph2Se and Ph2Te  Diphenyltelluride also reacted under identical conditions, but at a significantly slower rate.  Only a 15% conversion into triphenyltelluronium triflate was observed after 48 h in CHCl3 Ph2X +conds.aentry solv. yield of 3.45 (%)c asbcde SesSeTeTeTe100d100d153671Ph3X+OTf-X time (h) conv. (%)b CHCl3sDCECHCl3DCECHCl3 24b244848168 943911430e613.42 3.18 3.45aConditions: 0.1 M solution of Ph2IOTf (1.0 equiv) in the indicated solvent(1 mL), 1.5 equiv of Ph2X, in a thick-walled glass tube sealed with a Teflonscrewcap and heated in an oil bath at 120 °C, for the time listed. bConversion calculated by 1H NMR. cYield after column chromatographydNo iodonium detected by 1H NMR. eContaminated (see text)Ph2IOTf67  (120 °C oil bath temperature; Table 3.4, entry c).  This abnormally slow reaction rate could be attributed to the weak bonding interaction between tellurium and iodine (46 kcal/mol for         Te–I).108  This would cause a higher reversibility of the first step of the mechanism (Scheme 3.3, p. 59), and therefore diminish the rate of the reaction. A solvent change to DCE resulted in higher conversion over the same period of time (Table 3.4, entry d), but the desired triphenyltelluronium triflate was accompanied by a byproduct tentatively assigned as 3.46 (Figure 3.1), on the basis of the following spectral evidence.  The mass spectrum of the compound showed signals centered at m/z = 342.9814 (ESI HRMS) corresponding to the molecular mass of [Ph2126TeCH2CH2Cl]+ and exhibiting the correct isotopic pattern for the presence of one chlorine and one tellurium atom.  The 1H NMR spectrum (Figure 3.1) showed an AA’BB’ pattern centered at 4.18 ppm and a doublet at 7.95 ppm.  The 4.18 ppm signal seems to be in accord with the presence of a chloroethyl chain, while the more downfield signal is typical for the aromatic protons ortho to the Te atom in a telluronium salt.  By-product 3.46 most likely arises from nucleophilic attack of diphenyl telluride onto 1,2-dichloroethane, and it proved to be difficult to fully separate from triphenyltelluronium triflate.  Thus, chloroform appears to be the solvent of choice for the arylation of diphenyl telluride.  Conversions and yields may be improved by letting the reaction proceed for 7 days (Table 3.4, entry e), in which case triphenyltelluronium triflate was obtained in 61% yield after chromatography.   68   Figure 3.1 1H NMR (300 MHz, acetone-d6) signals of the presumed adduct formed by substitution of dichloroethane with Ph2Te  Triphenyltelluronium triflate 3.35c was not known prior to our preparation; therefore, we confirmed the structure by single-crystal X-ray diffractometry.  The O−Te distances between the Te(IV) center and the triflate counterion is found to be between 2.894 and 2.947 Å. As typical covalent Te–O bonds are normally 1.9–2.0 Å in length, this finding is indicative of weak ionic interactions.109  Greater bond lengths (2.65−2.93 Å) have been reported for (tetraphenylimido-diphosphinato)triphenyltellurium(IV) and were categorized by Drake and coworkers as secondary interactions.110  As for the phenyl groups on the tellurium(IV) center, while all C−Te bond lengths are very similar (2.112 Å; 2.115 Å; 2.133 Å), one of the C–Te–C bond angles in significantly wider than the other two: 102.6°, compared to 94.0° and 95.6°.  The bond angles are constricted to accommodate bonding with the p electrons of telluride, as heavy elements tend to resist hybridization due to energetic mismatch between the s and p electrons.111  We have conclusively demonstrated that the more electrophilic diaryliodonium triflates enable the metal-free preparation of triarylsulfonium compounds under mild conditions in non-donor solvents.  This method also extends to the preparation of triarylselenonium and triaryltelluronium salts, syntheses of the latter compounds are still limited and our methodology TeClOTfHaHc HbHcHa/Ha'/Hb/Hb'Ha'Hb'3.46Ph2IOTf69  could allow for more flexibility in their preparation, leading to application in organometallic chemistry.  3.3 Future Work The possibility of preparing sulfonium species by thermal treatment of sulfides allows for interesting possibilities for organic chemistry, as related species are already established as useful reagents and intermediates.  A notable example would be the use of dimethylsulfonium and dimethylsulfoxonium ylides as methylene transfer agents, allowing for the preparation of epoxides, aziridines and cyclopropanes in what is now referred to as the Corey-Chaykovsky reaction.  The mechanism involves initially the nucleophilic attack of the ylide to a p-bond – whether it be the alkene of an enone, a ketone or an imine – before closing the three-membered ring by nucleophilic displacement of the sulfonium ion (Scheme 3.8).     Scheme 3.8 Mechanism of the Corey-Chaykovsky reaction   The second stage of the Corey-Chaykovsky reaction serves as one of the basis of our interest in using the arylation technology developed in Chapter 3 to promote the cyclization of hydrocarbons such as terpenes.  We envision the arylation of a sulfide contained in the scaffold and subsequent nucleophilic displacement of the sulfonium salt by an appropriately placed olefin to obtain a cyclohexene, after proton elimination (Scheme 3.9).  This process would be an SX XS– SMe2 XX = C(CO)R, N, O70  interesting alternative to the Lewis-acid catalyzed cyclization of polyolefinic acetals and alcohols established by Johnson.112    Scheme 3.9 Proposed cyclization via arylation of sulfides   Preliminary work already has shown the reaction to be feasible with citronellol derivatives, although a mixture of olefin regioisomers was obtained initially (Scheme 3.10).113    Scheme 3.10 Cyclization of citronellyl sulfide promoted by arylation with di(4-bromophenyl)iodonium triflate113  We hypothesized that the olefin isomerization was caused by trace amounts of triflic acid released by thermolysis of the diaryliodonium triflate.  When the cyclization was performed with excess diaryliodonium triflate and added calcium carbonate, the only product identified by 1H NMR was the p-menth-3-ene product, meaning this would be the kinetic product of the cyclization following hydride shift and proton elimination.  Work is currently underway to expand the methodology to scaffolds which can be efficiently isolated without volatility issues.  SPhAr2IOTfS Ar- H+R R R RPhSPhIOTfBr Br85°C, CDCl3(1 equiv)71   Scheme 3.11 Cyclization of citronellyl sulfide with di(4-bromophenyl)iodonium triflate in the presence of calcium carbonate SPhIOTfBr BrCaCO3 (3 equiv)85°C, CDCl3(4 equiv)72  Conclusion The present work has established the possibility of performing metathetic aryl exchange on diaryliodonium salts, a reaction involving the action of aryl iodides as nucleophiles on the hypervalent iodine reagent.  It was determined that electronic factors are key to the success of the transformation: entering aryl iodides must have a higher electron-rich character than the departing one.  Preference for the transfer of the more electron-rich arene to the diaryliodonium produced via metathesis was noted, an observation that goes against the selectivities generally observed for arylation with such reagents.  We proposed an alternate mechanism where the expulsion of the more nucleofugal iodoarene is the controlling factor for the outcome of the reaction.  We challenged our hypothesis by preparing thiophene-substituted diaryliodonium salts, as it was determined by semi-empirical calculations 2-iodothiophene exhibits a high positive character on its iodine atom, making this group a superior leaving group.  This resulted in an expanded scope of the iodonium metathesis; aryl iodides which were unreactive with previous l3-iodanes underwent metathesis (see Table 2.5, p. 46).  This was further supported by the fact that mesityl substituted diaryliodonium salts, known to have enhanced reactivity due to the presence of the ortho-methyl groups, did not allow for such an expanded scope of the metathesis reaction.  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G.; Brown, A.; Thompson, A. L.; Kennepohl, P.; Beer, P. D. J. Am. Chem. Soc. 2015, 137, 499. 91.  All computational work was performed by M. A. Ciufolini using the Hyperchem® package. For an overview of methods available, see: Thiel, W. Adv. Chem. Phys. 1996, 93, 703. 92.  Fleming, P. J.; Wallace, J. J. Commun. ACM 1986, 29, 218. 93.  (a) Stang, P. J.; Tykwinski, R.; Zhdankin, V. V. J. Heterocyclic Chem. 1992, 29, 815. (b) Stang, P. J.; Zhdankin, V. V.; Tykwinski, R. Tetrahedron Lett. 1992, 33, 1419. 94. (a) Schoolery, J. N. Prog. NMR Spectrosc. 1977, 11, 79. (b) Becker, E. D. High Resolution NMR; Academic Press: New York, 1980, pp. 259-265. (c) Field, L. D.; Sternhell, S., eds., Analytical NMR; John Wiley & Sons: Chichester, 1989, pp. 41-63.  See Experimental Section for further details. 81                                                                                                                                                         95.  The Dudley group has been studying microwave-assisted reactions with improved rigor. For a modern understanding of the process, see: Dudley, G. B.; Richert, R.; Stiegman, A. E. Chem. Sci. 2015, 6, 2144. 96.  (a) Yan, J.; Zhou, Z.; Zhu, M. Synth. Commun. 2006, 36, 1495. (b) Yan, J.; Hu, W.; Zhou, W. Synth. Commun. 2006, 36, 2097. (c) Zhu, M.; Song, Y.; Cao, Y. Synthesis 2007, 6, 853. (d) Vaddula, B. R.; Varma, R. S.; Leazer, J. Eur. J. Org. Chem., 2012, 6852. (e) Kumar, D.; Arun, V.; Pilania, M.; Shekar, K. P. C. Synlett, 2013, 24, 831. (f) Deeming, A. S.; Russell, C. J.; Hennessy, A. J.; Willis, M. C. Org. Lett., 2014, 16, 150. 97. (a) Graskemper, J. W.; Wang, B.; Qin, L.; Neumann, K. D.; DiMagno, S. G. Org. Lett. 2011, 13, 3158. (b) Ichiichi, N.; Canty, A. J.; Yates, B. F.; Sanford, M. S. Org. Lett. 2013, 15, 5134. 98.  5-[18F]fluorouracil is then an important radiotracer due to its potential use for the detection of tumors and metabolic studies using PET: Abe, Y.; Fukuda, H.; Ishiwata, K.; Yoshioka, S.; Yamada, K.; Endo, S.; Kubota, K.; Sato, T.; Matsuzawa, T.; Takahashi, T.; Ido, T. Eur. J. Nucl. Med. 1983, 8, 258 99.  (a) Crivello, J. V.; Lam, J. H. W. J. Polym. Sci. Polym. Chem. Ed. 1979, 17, 1059. (b) Crivello, J. V.; Lam, J. H. W. J. Polym. Sci. Chem. Ed. 1979, 17, 977. 100. Crivello, J. V. J. Polym. Sci. Part A: Polym. Chem. 1999, 37, 4241. 101. Knapczyk, J. W. and McEwen, W. E. J. Org. Chem., 1970, 35, 2539. 102. Results from section 3.1 were published: Racicot, L.; Kasahara, T.; Ciufolini, M. A. Org. Lett. 2014, 16, 6382. 82                                                                                                                                                         103. (a) Nesmeyanov, A. N.; Makarova, L. G.; Tolstaya, T. P. Tetrahedron 1957, 1, 145. (b) Knapczyk, J. W.; McEwen, W. E. J. Am. Chem. Soc. 1969, 91, 145. 104. Ochiai, M.; Nagaoka, T.; Sueda, T.; Yan, J.; Chen, D.-W.; Miyamoto, K. Org. Biomol. Chem. 2003, 1, 1517. 105. Crivello, J. V.; Lam, J. H. W. J. Polym. Sci. Chem. Ed. 1979, 17, 1047. 106. Lin, T.-P.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2013, 52, 3864. 107. Cohen, S.C.; Massey, A. G. In Advances in Fluorine Chemistry; Tatlow, J. C.; Peacock, R. D.; Hyman, H. H. (Eds.); Butterworths: London, 1970, Vol. 6, pp. 234-235. 108. Dean, J. A. Lange’s Handbook of Chemistry; McGraw-Hill: New York, 1999, 15th ed., p. 4.51. 109. (a) Sundberg, M. R.; Uggla, R.; Laitalainen, T.; Bergman, J. J. Chem. Soc., Dalton Trans. 1994, 3279. (b) Fleischer, H.; Schollmeyer, D. Inorg. Chem. 2001, 40, 324.  110. Drake, J. E.; Silvestru, A.; Yang, J.; Haiduc, I. Inorg. Chim. Acta 1998, 271, 75. 111. Joannopoulos, J. D.; Kastner, M. Solid State Commun. 1975, 17, 221. 112. Johnson, W. S. Bioorg. Chem. 1976, 5, 51. 113. Experiment performed by Lee, H. J. 83  Appendix A: Semi-empirical Estimation of the Charge on Iodine Atoms of Selected Organoiodine Compounds Structure MNDO MNDO/d AM1 PM3 Geometric mean 1-iodopropane 0.030 -0.058 0.046 -0.004 0.024 iodomesitylene 0.114 0.060 0.131 0.021 0.066 4-iodotoluene 0.123 0.077 0.139 0.016 0.068 iodobenzene 0.122 0.075 0.140 0.017 0.068 1-iodonaphthalene 0.117 0.067 0.138 0.022 0.070 4-iodoanisole 0.122 0.076 0.141 0.019 0.071 4-chloro-iodobenzene 0.134 0.089 0.150 0.030 0.086 4-iodo-bromobenzene 0.132 0.091 0.152 0.033 0.088 4-fluoro-iodobenzene 0.132 0.091 0.151 0.036 0.090 Me 4-iodobenzoate 0.135 0.095 0.155 0.038 0.093 4-CF3-iodobenzene 0.145 0.108 0.162 0.051 0.107 3,5-di(CO2Me)iodoPh 0.145 0.107 0.171 0.060 0.112 2-Cl-5-iodopyridine 0.152 0.115 0.173 0.068 0.120 4-nitro iodobenzene 0.152 0.118 0.173 0.067 0.120 5-I-N,N-di-Me-uracyl 0.174 0.148 0.209 0.127 0.162 2-I-benzothiophene 0.179 0.154 0.205 0.134 0.166 2-iodothiophene 0.181 0.154 0.202 0.136 0.166 2-iodofuran 0.203 0.185 0.233 0.156 0.192 2-iodo benzofuran 0.201 0.186 0.235 0.157 0.193   84  Appendix B: Use of 1H and Quantitative 13C NMR Spectroscopy for the Calculation of the Ratios of Diaryliodonium Triflates in Isolated Mixtures To illustrate how the ratios of the complex mixtures obtained when phenyl(2-thienyl)iodonium triflate is employed as metathesis substrate, the present section will detail the data analysis for entry a of Table 2.6 (p. 47). First, the 1H and quantitative 13C NMR spectra are integrated and labelled to associate the signals to the mixture components (spectra are presented on p. 141 and following).  Assignment of the frequencies was done by comparison with spectra of the pure iodonium triflates, prepared separately.    From the quantitative 13C NMR spectrum, we can obtain the relative ratios of 2.53, 2.54a, 2.56a, and 2.16. The proportion of 2.55a will be determined using the 1H NMR spectroscopy data as only one 13C signal is sufficiently resolved. Phenyl(2-thienyl)iodonium triflate (2.53): 1.00 + 0.87 + 0.97 + 0.914 = 0.94 (4-Chlorophenyl)phenyliodonium triflate (2.54a): 4.77 + 9.30 2 + 8.22 23 = 4.51 DCE, 80°C+2I2.16IPh IOTf+ + IPhS2.532.54a2.52a2.51aIPhSIClClCl ClPhOTfOTf OTfOTf85  Di(4-Chlorophenyl)iodonium triflate (2.52a): 2.83 2 + 6.31 42 = 1.50 Diphenyliodonium triflate (2.16): 1.87 4 + 0.87 2 + 0.75 24 = 0.42 The ratio of (4-chlorophenyl)(2-thienyl)iodonium triflate (2.51a) is obtained from the 1H NMR spectra following the fact that: Multiplet at 8.07-8.03 ppm corresponds to 2.53 (1H), 2.51a (1H) and integrates for 1.04. Multiplet at 7.81-7.72 ppm corresponds to 2.53 (1H), 2.54a (1H) and 2.16 (2H) and integrates for 4.12. To isolate the contribution of 2.51a in the area of the first multiplet, one must adjust the ratios obtained by the quantitative 13C NMR experiment as follows: 4.120.94 + 4.51 + 2×0.42 = 0.66 1.04 − 0.66×0.94 = 0.42 According to 1H NMR spectroscopy, there is therefore a 0.42 : 0.62 ratio of 2.51a to 2.53, which is equivalent to a 0.64 : 0.94 ratio to use the 13C integration of 2.53. We can then finally combine the ratio of the mixture of 2.53:2.54a:2.51a:2.52a:2.16 as 0.94 ∶ 4.51 ∶ 0.64 ∶ 1.50 ∶ 	0.42 2.2 ∶ 11 ∶ 1.5 ∶ 3.6 ∶ 1.0 This ratio is then used to obtain an averaged molecular weight of the mixture in order to calculate the mass recovery of the metathesis: 86  2.2×436.20 + 11×464.62 + 1.7×470.64 + 3.6×499.06 + 1.0×430.192.2 + 11 + 1.7 + 3.6 + 1.0= 466.53	2/456 74	42466.53	42 ∙ 445689 10.2	4456 ×100% = 79% 87  Appendix C: Experimental Section General. Unless specified otherwise, reactions were performed under dry argon in oven–dried glassware equipped with Teflon™ stirbars. Flasks were fitted with rubber septa for the introduction of substrates, reagents and solvents via syringe in a single portion. Flash chromatography was performed with SiliCycle SiliaFlash® F60 230-400 mesh silica gel. Thin layer chromatography was performed on EMD Silica gel 60 F254 plates and visualized under UV light (254 nm) or by treatment with alkaline KMnO4 stain. mCPBA was dried in vacuo until the flask was no longer cold and used as 90% pure reagent (determined by iodometric titration). Tetrahydrofuran was distilled from Na/benzophenone, while dichloromethane was distilled over CaH2 prior to use. All other commercially available chemicals were used without further purification. Instrumentation. 1H and 13C NMR spectra were recorded on Bruker model AVANCE II+ 300 (300 MHz for 1H, 75.5 MHz for 13C, 282 MHz for 19F, 57 MHz for 77Se, and 94 MHz for 125Te) spectrometer using deuteroacetone (C3D6O) or deuterated chloroform (CDCl3) as the solvent.  For the obtention of quantitative 13C NMR spectra, the 13C/1H-decoupled experiment was modified as follows: T1 = 300 s; O1p = 120 ppm; SW = 60 ppm; ns = 124 scans.  Ratios were calculated using averages of the integration of assigned signals for each component and verified against the integrations of the overlapped signals in the 1H NMR spectra.  A verification was made with a sample where the ratios were determined by both 1H and quatitative 13C NMR spectroscopy and the ratios calculated by each method were within 6% of difference.  Some frequencies in the 13C NMR spectra were left unassigned due to the ambiguity of their assignment or overlap of signals from either multiple non-equivalent protons or protons from different iodonium species.  Chemical shifts are reported in parts per million (ppm) on the scale 88  and coupling constants, J, are in hertz (Hz).  Low-resolution mass spectra (m/z) were obtained in the electrospray (ESI) mode on a Waters Micromass ZQ mass spectrometer.  High-resolution mass spectra (m/z) were recorded in the electrospray (ESI) mode on a Micromass LCT mass spectrometer by the UBC Mass Spectrometry laboratory.  Melting points (uncorrected) were measured on a Mel–Temp apparatus.  X-ray crystal measurements were made on a Bruker APEX DUO diffractometer by Dr. Brian Pratick of UBC.    89  Preparation of Iodonium Triflate Salts The following compounds were prepared as described in the literature and purified by dissolving in the minimal volume of hot MeCN, followed by addition of excess cold Et2O to induce crystallization: diphenyliodonium triflate,1 (4-nitrophenyl)phenyliodonium triflate,1 (4-anisyl)(4-nitrophenyl)iodonium triflate,1 di(4-anisyl)iodonium triflate,2 phenyl(2-thienyl)iodonium triflate.1  Substantially the same procedures afforded the following diaryliodonium triflate:  Preparation of (mesityl)(4-nitrophenyl)iodonium triflate (Table 2.3, entries i-k)  4-Iodonitrobenzene (249 mg, 1.0 mmol) was dissolved in 2 mL CH2Cl2. mCPBA (242 mg, 90 %, 1.25 mmol, 1.25 equiv.) was combined before dropwise addition of trifluoromethanesulfonic acid (0.2 mL, 2.0 mmol, 2.0 equiv.). The mixture was stirred for 10 min and cooled to 0 °C. Mesitylene (0.15 mL, 1.1 mmol, 1.1 equiv.), previously diluted with 1 mL CH2Cl2, was added dropwise over 5 min and the reaction mixture was left to stir for 30 min while warming to rt, after which it was concentrated under reduced pressure. The residue was dissolved in Et2O and stirred for 30 min to allow full precipitation of the product. Crude mesityl-4-nitrophenyliodonium triflate (510 mg, 97%) was obtained after vacuum filtration. The product was purified by recrystallization by dissolving in minimal hot MeCN, and then crystallized by                                                 1. Bielawski, M.; Zhu, M.; Olofsson, B. Adv. Synth. Catal. 2007, 349, 2610 – 2618. 2. Zhu, M.; Jalalian, N.; Olofsson, B. Synlett, 2008, 4, 592-596. IOTfNO2MeMeMe90  adding excess cold Et2O, affording mesityl-4-nitrophenyliodonium triflate as a white solid (450 mg, 87%), mp: 199-201 °C (decomp.). 1H: 8.34 (ABq, 4 H, ΔνAB = 0.02, JAB = 9.2 Hz), 7.34 (s, 2 H), 2.73 (s, 6 H), 2.39 (s, 3 H); 13C: 150.11, 144.94, 142.82, 135.36, 130.47, 126.52, 121.14, 118.20, 26.23, 20.14; HRMS (ESI): calcd for C15H15NO2I ([M – TfO–]+): 368.0148; found 368.0143.  Preparation of Di(2-thienyl)iodonium Triflate (2.41; Tables 2.5, 2.7)  The triflate salt is prepared by anion exchange from di(2-thienyl)iodonium tosylate. The latter was prepared according to the literature, and purified by first rinsing the crude mass with Et2O (4 x 50 mL). The oil was then suspended in acetone and eluted through a plug of basic alumina with 100 mL 10% MeOH/acetone. After the dark fraction was concentrated, the crude di(2-thienyl)iodonium tosylate was recrystallized by dissolution in minimal acetone and adding excess Et2O to induce precipitation. The tan solids were recrystallized a second time with the same solvent system to afford dithienyliodonium tosylate as light tan solids (2.387 g, 51%), analytical in accordance with past reports.2 Di(2-thienyl)iodonium tosylate (1.972 g, 3.29 mmol, 1.0 equiv.) was suspended in 30 mL CH2Cl2 (distilled over CaH2) and cooled to -40 °C. Trifluoromethanesulfonic acid (0.88 mL, 9.87 mmol, 3.0 equiv.) was diluted in 10 mL CH2Cl2 (distilled over CaH2) before adding dropwise to the iodonium. The reaction needed to be swirled manually to ensure proper stirring as the mixture congeals. After the addition was completed, the mixture is left to stir for 1 h while warming to rt. I OTfSS91  The crude mixture was concentrated under reduced pressure (water bath no more than 35 °C), and the resulting dark green solids were rinsed with Et2O (2 x 25 mL). The crude dithienyliodonium triflate was then dissolved in acetone, and heated to force the production of black solids before filtering through a pad of basic alumina with acetone. The filtrate was concentrated under reduced pressure (water bath no more than 35 °C). Recrystallization by dissolving in minimal MeCN and adding excess Et2O to force precipitation yielded dithienyliodonium triflate as an off-white solid (997 mg, 68%, 37% over two steps), mp: 114-118 °C (decomp.) 1H (Me2CO-d6):  8.20 (dd, J = 1.3, 3.9 Hz, 2 H) 8.01 (dd, J = 1.3, 5.4 Hz, 2 H) 7.23 (dd, J = 3.9, 5.4 Hz, 2 H). 13C (Me2CO-d6): 142.18, 138.78, 130.54, 100.75. HRMS (ESI) calcd for C8H6S2I+ ([M – TfO–]+): 292.8956; found 292.8943.  General Procedure for Melt Metathesis Reactions. The aryl iodide (0.5 mmol, 5 equiv.) was combined with diphenyliodonium triflate (0.1 mmol) in a 0.2 mL microwave vial, which was then sealed with a crimped cap. The mixture was heated at 120 °C (oil bath temperature) for 24 h, before being cooled to rt. The crude material was purified by flash chromatography (10-40% acetone/ CH2Cl2 gradient).  Melt metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry d)  4-iodotoluene (109 mg, 0.5 mmol) and Ph2IOTf (43 mg, 0.1 mmol) combined to afford 60% (27 mg) of mixture. IOTf I Me (5 equiv.)neatIOTf2.16 2.18 2.19+MeIOTfMe2ratio 2.16 : 2.18 : 2.19         1.5  :  1.0  :  2.392  1H (acetone-d6): diphenyliodonium triflate: 8.34 (app dd, J = 8.6, 1.0 Hz, 4 H), 7.74 (app tt, J = 7.5, 1.7 Hz, 2 H), 7.59 (app t, J = 7.9 Hz, 4 H). phenyl(4-tolyl)iodonium triflate: 8.34-8.28 (m, 2 H), 8.24-8.19 (m, 2 H), 7.76-7.70 (m, 1 H), 7.64-7.60 (m, 2 H), 7.43-7.37 (m, 2 H), 2.40 (s, 3 H). di(4-tolyl)iodonium triflate: 8.18 (app d, J = 8.5 Hz, 4 H), 7.39 (app d, J = 8.0 Hz, 4 H), 2.40 (s, 6 H). 13C (acetone-d6): 144.50, 136.48, 136.32, 136.29, 133.64, 133.47, 133.00, 124.22, 119.96, 115.33, 111.77, 21.26. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  General Procedure for Metathesis Reactions in Solution  A 15 mL heavy walled pressure vessel was charged with the iodonium triflate in 0.5 mL 1,2-dicholoroethane (0.2M for iodonium), to which the aryl iodide (5 equiv.) was added in a single portion before sealing with a screw cap. The mixture was heated at 120 °C (oil bath temperature) for the amount of time specified, before being cooled to rt and concentrated under reduced pressure. The crude material was purified by flash chromatography (10-40% acetone/ CH2Cl2 gradient).  Solution metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry e)  4-iodotoluene (109 mg, 0.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 24 h to afford 48% (22 mg) of mixture. IOTf I Me (5 equiv.)DCEIOTf2.16 2.18 2.19+MeIOTfMe2ratio 2.16 : 2.18 : 2.19         1.0  :  10   :  2993  1H (acetone-d6): phenyl(4-tolyl)iodonium triflate: 8.31 (app d, J = 7.8 Hz, 2 H), 8.24-8.19 (m, 2 H), 7.74 (app t, J = 7.5 Hz, 1 H), 7.59 (app t, J = 7.9 Hz, 2 H), 7.44-7.40 (m, 2 H), 2.41 (s, 3 H). di(4-tolyl)iodonium triflate:  8.18 (app d, J = 8.4 Hz, 4 H), 7.40 (app d, J = 8.3 Hz, 4 H), 2.41 (s, 6 H). 13C: 144.52, 144.48, 136.51, 136.32, 136.29, 133.70, 133.66, 133.65, 133.36, 132.96, 111.89, 111.86, 21.28. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between Ph2IOTf and 1-iodonaphthalene (Table 2.2, entry a)  1-iodonaphthalene (73 µL, 0.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 26 h to afford 13% (7 mg) of mixture. 1H (acetone-d6): (1-naphthyl)phenyliodonium triflate: 8.88 (d, J = 7.5 Hz, 1 H), 8.41-8.31 (m, 4 H), 8.10 (d, J = 8.1 Hz, 1 H), 7.85 (app t, J = 8.2 Hz, 1 H), 7.80-7.57 (m, 3 H), 7.53 (app t, J = 7.6 Hz, 2 H). di(1-naphthyl)iodonium triflate: 8.93 (d, J = 7.5 Hz, 2 H), 8.53 (d, J = 8.5 Hz, 2 H), 8.28 (d, J = 8.2 Hz, 2 H), 8.04 (d, J = 8.3 Hz, 2 H), 7.85 (app t, J = 8.2 Hz, 2 H), 7.75-7.58 (m, 4 H). 13C: 139.26, 138.97, 138.89, 136.46, 135.98, 135.90, 135.27, 135.03, 133.52, 133.34, 133.06, 132.98, 132.46, 131.00, 130.90, 130.62, 130.55, 129.67, 129.56, 129.14, 129.07, 128.61, 128.50, IOTfI(5 equiv.)DCEIOTf2.16 2.21a 2.22aI2OTfratio 2.16 : 2.21a : 2.22a          0    :   2.0   :   1.0+94  124.25, 119.99, 118.23, 115.23. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between Ph2IOTf and 4-iodoanisole (Table 2.2, entry b)  4-iodoanisole (117 mg, 0.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 25 h to afford 80% (37 mg) of mixture. 1H (acetone-d6): (4-anisyl)phenyliodonium triflate: 8.32-8.24 (m, 4 H), 7.74 (app t, J = 7.5 Hz, 1 H), 7.59 (app t, J = 7.9 Hz, 2 H), 7.16-7.11 (m, 2 H), 3.88 (s, 3 H). di(4-anisyl)iodonium triflate: 8.23 (app d, J = 9.2 Hz, 4 H), 7.11 (app d, J = 9.2 Hz, 4 H), 3.88 (s, 6 H). 13C: 163.95, 163.79, 138.69, 138.22, 136.48, 135.97, 133.24, 132.87, 124.19, 119.93, 118.68, 118.54, 115.91, 104.36, 103.60, 56.24. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between Ph2IOTf and 1-bromo-4-iodobenzene (Table 2.2, entry e)  IOTf I OMe (5 equiv.)DCEIOTf2.16 2.21b 2.22b+MeOIOTfMeO2ratio 2.16 : 2.21b : 2.22b         1.3  :   27    :   23IOTf I Br (5 equiv.)DCEIOTf2.16 2.21e 2.22e+BrIOTfBr2ratio 2.16 : 2.21e : 2.22e         1.3  :   2.0   :   2.995  1-bromo-4-iodobenzene (283 mg, 0.5 mmol) was added in a single portion to a solution of Ph2IOTf (86 mg, 0.2 mmol) in 0.5 mL DCE and stirred for 24 h to afford 64% (59 mg) of mixture. 1H (acetone-d6): diphenyliodonium triflate: 8.34 (app dd, J = 8.6, 1.0 Hz, 4 H), 7.74 (m, 2 H), 7.59 (app t, J = 7.9 Hz, 4 H). (4-bromophenyl)phenyl iodonium triflate: 8.34 (app dd, J = 8.6, 1.0 Hz, 2 H), 8.29 (app dd, J = 8.7, 2.1 Hz, 2 H), 7.74 (m, 3 H), 7.59 (app t, J = 7.9 Hz, 2 H). di(4-bromophenyl)iodonium triflate: 8.29 (app dd, J = 8.7, 2.1 Hz, 4 H), 7.74 (m, 4 H). 13C (acetone-d6): 138.36, 138.30, 136.54, 136.47, 135.94, 135.90, 133.55, 133.45, 133.02, 132.97, 128.31, 128.05, 127.93, 124.06, 119.80, 115.60, 115.23, 113.99, 113.61. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between (mesityl)(4-nitrophenyl)iodonium triflate and 4-iodotoluene (Table 2.3, entry i)  4-iodotoluene (109 mg, 0.5 mmol) was added in a single portion to a solution of (mesityl)(4-nitrophenyl)iodonium triflate (52 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 12 h to afford 26% (12 mg) of mixture. 1H (acetone-d6): (mesityl)(4-tolyl)iodonium triflate: 7.96 (app d, J = 8.5 Hz, 2 H), 7.43-7.36 (m, 2 H), 7.26 (s, 2 H), 2.71 (s, 6 H), 2.41 (s, 3 H), 2.35 (s, 3 H). IOTfI Me (5 equiv.)DCEIOTf2.26i2.27i 2.28i+MeIOTfMe2MeMeMeNO2Me MeMeratio 2.26i : 2.27i : 2.28i           0    :   1.0  :   7.096  di(4-tolyl)iodonium triflate: 8.18 (app d, J = 8.5 Hz, 4 H), 7.40 (app d, J = 8.4 Hz, 4 H), 2.41 (s, 6 H). 13C: 144.56, 143.27, 136.31, 135.35, 133.80, 133.68, 131.06, 124.28, 120.02, 111.83, 27.05, 21.27. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between (mesityl)(4-nitrophenyl)iodonium triflate and 4-iodoanisole (Table 2.3, entry j)  4-iodoanisole (117 mg, 0.5 mmol) was added in a single portion to a solution of (mesityl)(4-nitrophenyl)iodonium triflate (52 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 12 h to afford 37% (18 mg) of mixture. 1H (acetone-d6): (4-anisyl)(mesityl)iodonium triflate: 8.03 (app d, J = 9.2 Hz, 2 H), 7.25 (s, 2 H), 7.16-7.08 (m, 2 H), 3.87 (s, 3 H), 2.72 (s, 6 H), 2.34 (s, 3 H). di(4-anisyl)iodonium triflate: 8.22 (app d, J = 9.2 Hz, 4 H), 7.10 (app d, J = 9.1 Hz, 4 H), 3.87 (s, 6 H). 13C: 163.84, 143.11, 138.21, 130.98, 124.24, 119.98, 118.58, 104.35, 56.25, 29.84, 26.99, 20.92. (Unassigned spectrum of the mixture)   IOTfI OMe (5 equiv.)DCEIOTf2.26j2.27j 2.28j+MeOIOTfMe2MeMeMeNO2Me MeMeratio 2.26j : 2.27j : 2.28j           0    :   1.0  :   1397  Solution metathesis between (mesityl)(4-nitrophenyl)iodonium triflate and 1-iodonaphthalene (Table 2.3, entry k)  1-iodonaphthalene (73 µL, 0.5 mmol) was added in a single portion to a solution of (mesityl)(4-nitrophenyl)iodonium triflate (52 mg, 0.1 mmol) in 0.5 mL DCE and stirred for 12 h to afford 27% (14 mg) of mixture. 1H (acetone-d6): (mesityl)(4-nitrophenyl)iodonium triflate: 8.37-8.29 (m, 4 H), 7.32 (s, 2 H), 2.71 (s, 6 H), 2.38 (s, 3 H). di(1-naphthyl)iodonium triflate: 8.93 (dd, J = 7.5, 0.8 Hz, 2 H), 8.53 (d, J = 8.3 Hz, 2 H), 8.31-8.26 (m, 2 H), 8.04 (d, J = 8.1 Hz, 2 H), 7.85 (ddd, J = 8.3, 7.1, 1.2 Hz, 2 H), 7.72 (app ddd, J = 8.0, 7.3, 0.7 Hz, 2 H), 7.62 (t, J = 7.8, 2 H). (mesityl)(1-naphyl)iodonium triflate and (4-nitrophenyl)(1-naphthyl)iodonium triflate were only detected through LC-MS and peak assignments for 1H NMR was not possible. 13C: 145.62, 143.56, 143.53, 138.94, 136.16, 136.14, 135.90, 135.05, 132.46, 131.26, 130.91, 130.54, 129.58, 129.06, 128.50, 127.30, 124.20, 122.56, 119.94, 118.07, 27.10, 21.02. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)     I(5 equiv.)DCEIOTf2.27k 2.28k+I2OTfIOTf2.26kMeMeMeNO2MeMeMeratio 2.26k : 2.27k : 2.28k          8.4   :   1.0   :   8.498  Solution metathesis between di(2-thienyl)iodonium and 1-iodotoluene (Scheme 2.11)   4-iodotoluene (218 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 48 h at 80 °C to afford 68% (61 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.23-8.11 (m, 2H), 8.03-7.94 (m, 2H), 7.25-7.18 (m, 2H).  (2-thienyl)(4-tolyl)iodonium triflate: 8.23-8.11 (m, 3H), 8.03-7.94 (m, 1H), 7.38 (app d, J = 8.3 Hz, 2H), 7.25-7.18 (m, 1H).  di(4-tolyl)iodonium triflate: 8.23-8.11 (m, 4H), 7.38 (app d, J = 8.3 Hz, 4H). 13C (acetone-d6): di(2-thienyl)iodonium triflate: 142.25, 138.79, 130.67, 100.75.  (2-thienyl)(4-tolyl)iodonium triflate: 144.58, 142.05, 138.65, 135.72, 133.54, 130.42, 114.66, 97.44, 21.23.  di(4-tolyl)iodonium triflate: 144.45, 136.28, 133.59, 111.60.  Solution metathesis between di(2-thienyl)iodonium and 1-chloro-4-iodobenzene (Table 2.5, entry a)   DCE, 80°C+2IOTf2.482.492.50I-OTfSIMe MeSI-OTfSMeratio 2.48 : 2.49 : 2.50         1.5  :  2.8  :   1.0DCE, 80°C+2IOTf2.482.51a2.52aI-OTfSICl ClSI-OTfSClratio 2.48 : 2.51a : 2.52a         7.4  :   6.3   :   1.099  1-Chloro-4-iodobenzene (238 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 48 h at 80 °C to afford 61% (56 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.21 (dd, J = 1.3, 3.9 Hz, 2H), 8.01 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-chlorophenyl)iodonium triflate: 8.34 (app d, J = 8.9 Hz, 2H), 8.24 (dd, J = 1.3, 3.8 Hz, 1H), 8.05 (dd, J = 1.3, 5.4 Hz, 1H), 7.64 (app d, J = 8.9 Hz, 2H), 7.27 (dd, J = 3.9, 5.4 Hz, 1H).  di(4-chlorophenyl)iodonium triflate: 8.37 (app d, J = 8.8 Hz, 4H), 7.64 (app d, J = 8.9 Hz, 4H). 13C (acetone-d6): 142.07, 139.52, 139.19, 138.65, 138.31, 137.48, 133.00, 132.86, 130.80, 130.46, 124.01, 119.76, 115.89, 100.83, 97.61. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between di(2-thienyl)iodonium and 1-bromo-4-iodobenzene (Table 2.5, entry b)  1-Bromo-4-iodobenzene (283 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 80 °C to afford 60% (61 mg) of a mixture of products. DCE, 80°C+2IOTf2.482.51b2.52bI-OTfSIBr BrSI-OTfSBrratio 2.48 : 2.51b : 2.52b         1.2  :   2.8   :   1.0100  1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.19 (dd, J = 1.3, 3.9 Hz, 2H), 8.00 (dd, J = 1.3, 5.4 Hz, 2H), 7.23 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-bromophenyl)iodonium triflate: 8.26 (app d, J = 8.8 Hz, 2H), 8.22 (dd, J = 1.3, 3.8 Hz, 1H), 8.04 (dd, J = 1.3, 5.4 Hz, 1H), 7.78 (app d, J = 8.8 Hz, 2H), 7.26 (dd, J = 3.8, 5.4 Hz, 1H).  di(4-bromophenyl)iodonium triflate: 8.29 (app d, J = 8.8 Hz, 4H), 7.78 (app d, J = 8.8 Hz, 4H). 13C (Me2CO-d6): 142.73, 142.04, 139.19, 138.63, 138.36, 137.51, 135.92, 135.78, 130.76, 130.42, 128.04, 127.85, 123.92, 119.67, 116.66, 113.82, 100.77, 97.46. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between di(2-thienyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.5, entry c)  1-Fluoro-4-iodobenzene (115 µL, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 48 h at 80 °C to afford 82% (75 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.18 (dd, J = 1.3, 3.9 Hz, 2H), 8.00 (dd, J = 1.3, 5.4 Hz, 2H), 7.21 (dd, J = 3.8, 5.4 Hz, 2H).  DCE, 80°C+2IOTf2.482.51c2.52cI-OTfSIF FSI-OTfSFratio 2.48 : 2.51c : 2.52c         1.0  :   3.2   :   2.2101  (2-thienyl)(4-fluorophenyl)iodonium triflate: 8.46-8.36 (m, 2H), 8.21 (dd, J = 1.3, 3.9 Hz, 1H), 8.01 (dd, J = 1.3, 5.4 Hz, 1H), 7.37 (app t, J = 8.8 Hz, 2H), 7.24 (dd, J = 3.8, 5.4 Hz, 1H). di(4-fluorophenyl)iodonium triflate: 8.46-8.36 (m, 4H), 7.37 (app t, J = 8.8 Hz, 4H). 13C (acetone-d6): 167.50, 167.39, 164.14, 164.04, 142.53, 142.05, 139.51, 139.39, 139.02, 138.85, 138.72, 138.64, 130.75, 130.46, 124.04, 120.48, 120.36, 120.17, 120.05, 119.78, 112.25, 112.21, 109.54, 100.94, 97.94. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between di(2-thienyl)iodonium and methyl 4-iodobenzoate (Table 2.5, entry d)   Methyl 4-iodobenzoate (262 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 48 h at 80 °C to afford 58% (52 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.20 (dd, J = 1.3, 3.9 Hz, 2H), 8.00 (dd, J = 1.3, 5.4 Hz, 2H), 7.23 (dd, J = 3.8, 5.4 Hz, 2H).  (2-thienyl)(4-carbomethoxyphenyl)iodonium triflate: 8.44 (app d, J = 8.7, 2H), 8.26 (dd, J = 1.2, 3.8 Hz, 1H), 8.12 (app d, J = 8.7 Hz, 2H), 8.06 (dd, J = 1.2, 5.4 Hz, 1H), 7.28 (dd, J = 3.9, 5.4 Hz, 1H), 3.91 (s, 3H). 13C (acetone-d6): 165.82, 143.04, 142.07, 139.42, 138.67, 135.84, 134.56, 133.14, 130.87, 130.45, 123.99, 122.70, 119.73, 100.79, 97.20, 53.03. (Signals unassigned, ratios obtained from the 1H NMR spectrum.) 2.48I-OTfSSDCE, 80°CIMeO2CI-OTfS2.51dCO2Meratio 2.48 : 2.51d         1.9  :   1.0102  Solution metathesis between di(2-thienyl)iodonium and dimethyl 5-iodoisophthalate (Table 2.5, entry e)   Dimethyl 5-iodoisophthalate (320 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 87% (83 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.21 (dd, J = 1.2, 3.8 Hz, 2H), 8.02 (dd, J = 1.2, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(5-isophthalyl)iodonium triflate: 9.10 (app d, J = 1.4, 2H), 8.77-8.73 (m, 1H), 8.34 (dd, J = 1.2, 3.9 Hz, 1H), 8.07 (dd, J = 1.2, 5.4 Hz, 1H), 7.30 (dd, J = 3.9, 5.4 Hz, 1H), 3.97 (s, 6H).  di(5-isophthalyl)iodonium triflate: 9.26 (app d, J = 1.4, 4H), 8.77-8.73 (m, 4H), 3.97 (s, 12H). 13C (acetone-d6): 164.49, 143.12, 142.03, 141.27, 140.03, 139.51, 138.62, 134.46, 133.91, 130.86, 130.44, 123.98, 119.73, 118.59, 115.47, 100.96, 53.39. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)     2.48I-OTfSSDCE, 80°CIMeO2CCO2MeI-OTfS2.51eMeO2C CO2Me+2IOTf2.52eMeO2CMeO2Cratio 2.48 : 2.51e : 2.52e         24   :   8.3   :   1.0103  Solution metathesis between di(2-thienyl)iodonium and 4-iodobenzotrifluoride (Table 2.5, entry f)   4-Iodobenzotrifluoride (147 µL, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 95% (84 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.22 (dd, J = 1.3, 3.9 Hz, 2H), 8.03 (dd, J = 1.3, 5.4 Hz, 2H), 7.26 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-trifluoromethyl)iodonium triflate: 8.57 (app d, J = 8.3 Hz, 2H), 8.29 (dd, J = 1.3, 3.9 Hz, 1H), 8.09 (dd, J = 1.6, 5.8 Hz, 1H), 7.96 (app d, J = 8.6 Hz, 2H), 7.31 (dd, J = 3.6, 5.8 Hz, 1H). 13C (acetone-d6): 141.92, 138.52, 130.38, 123.90, 119.64, 101.16. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between di(2-thienyl)iodonium and 1-iodo-4-nitrobenzene (Table 2.5, entry g)   2.48I-OTfSSDCE, 80°CIF3CI-OTfS2.51fCF3ratio 2.48 : 2.51f        >50  :   1.02.48I-OTfSSDCE, 80°CIO2NI-OTfS2.51gNO2ratio 2.48 : 2.51g         17   :   1.0104  1-Iodo-4-nitrobenzene (249 mg, 1.0 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (88 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 89% (79 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.20 (dd, J = 1.3, 3.9 Hz, 2H), 8.03 (dd, J = 1.3, 5.4 Hz, 2H), 7.23 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-nitrophenyl)iodonium triflate: 8.59 (app d, J = 9.2 Hz, 2H), 8.37 (app d, J = 9.2 Hz, 2H), 8.29 (dd, J = 1.2, 3.9 Hz, 1H), 8.07 (dd, J = 1.3, 5.4 Hz, 1H), 7.30 (dd, J = 3.9, 5.4 Hz, 1H). 13C (acetone-d6): 143.21, 141.91, 139.55, 138.51, 136.95, 130.89, 130.39, 128.17, 127.12, 123.91, 119.66, 115.40, 101.26. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between phenyl(2-thienyl)iodonium and 1-chloro-4-iodobenzene (Table 2.6, entry a)   1-Chloro-4-iodobenzene (238 mg, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 80 °C to afford 79% (74 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.42-8.32 (m, 2H), 8.25-8.21 (m, 1H), 8.07-8.03 (m, 1H), 7.81-7.72 (m, 1H), 7.69-7.58 (m, 2H), 7.29-7.25 (m, 1H).  DCE, 80°C+2i2.16I-OTfPh I-OTfOTf+ +PhI-OTfPhS2.532.54a2.52a2.51aI-OTfPhSIClClCl Clratio 2.53 : 2.54a :  2.51a :  2.52a :  2.16         2.2  :    11   :   1.5   :   3.6   : 1.0105  phenyl(4-chlorophenyl)iodonium triflate: 8.42-8.32 (m, 4H), 7.81-7.72 (m, 1H), 7.69-7.58 (m, 4H).  (2-thienyl)(4-chlorophenyl)iodonium triflate: 8.42-8.32 (m, 2H), 8.25-8.21 (m, 1H), 8.07-8.03 (m, 1H), 7.69-7.58 (m, 2H), 7.29-7.25 (m, 1H).  di(4-chlorophenyl)iodonium triflate: 8.42-8.32 (m, 4H), 7.69-7.58 (m, 4H).  diphenyliodonium triflate: 8.42-8.32 (m, 4H), 7.81-7.72 (m, 2H), 7.69-7.58 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.50, 138.97, 135.65, 130.72, 118.37, 97.26. phenyl(4-chlorophenyl)iodonium triflate: 139.50, 138.29, 136.50.  di(4-chlorophenyl)iodonium triflate: 139.59, 138.30.  diphenyliodonium triflate: 136.45, 115.18.  triflate anion (two of the four lines of the quadruplet): 123.96, 119.70.  Unassigned signals (ambiguous or resulting from signal overlap): 142.68, 139.14, 138.23, 137.46, 133.52, 133.40, 132.98, 132.93, 132.89, 132.86, 132.79, 115.58, 113.13, 112.72.   Solution metathesis between phenyl(2-thienyl)iodonium and 1-bromo-4-iodobenzene (Table 2.6, entry b)  DCE, 80°C+2i2.16I-OTfPhOTf+PhI-OTfPh2.532.54b2.52bI-OTfPhSIBrBrBrratio 2.53 : 2.54b :  2.52b :  2.16         3.8  :    12   :   4.1   :  1.0106  1-Bromo-4-iodobenzene (283 mg, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 80 °C to afford 79% (80 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.39-8.32 (m, 2H), 8.22-8.19 (m, 1H), 8.04-8.00 (m, 1H), 7.80-7.69 (m, 1H), 7.63-7.55 (m, 2H), 7.26-7.22 (m, 1H).  phenyl(4-bromophenyl)iodonium triflate: 8.39-8.32 (m, 2H), 8.32-8.24 (m, 2H), 7.80-7.69 (m, 3H), 7.63-7.55 (m, 2H).   di(4-bromophenyl)iodonium triflate: 8.32-8.24 (m, 2H), 7.80-7.69 (m, 2H).  diphenyliodonium triflate: 8.39-8.32 (m, 4H), 7.80-7.69 (m, 2H), 7.63-7.55 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate : 142.44, 138.91, 133.39, 97.60.  phenyl(4-bromophenyl)iodonium triflate:  138.27, 136.51, 133.52, 127.89, 113.66.  di(4-bromophenyl)iodonium triflate: 138.34, 128.00, 114.05.  diphenyliodonium triflate: 136.44, 115.48.  triflate anion (two of the four lines of the quadruplet): 123.98, 119.72.  Unassigned signals (ambiguous or resulting from signal overlap): 139.08, 137.49, 135.91, 135.87, 135.76, 135.64, 132.99, 132.94, 132.86, 130.72, 118.54, 115.63.  Solution metathesis between phenyl(2-thienyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.6, entry c)  DCE, 80°CI-OTfPh2.532.54cI-OTfPhSIFFratio 2.53 : 2.54c          7.4  :    1.0107  1-Fluoro-4-iodobenzene (115 µL, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 80 °C to afford 96% (84 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.40-8.32 (m, 2H), 8.23 (dd, J = 1.3, 3.9 Hz, 1H), 8.05 (dd, J = 1.3, 5.4 Hz 1H), 7.82-7.73 (m, 1H), 7.68-7.58 (m, 2H), 7.28 (dd, J = 3.9, 5.4 Hz, 1H).  phenyl(4-fluorophenyl)iodonium triflate: 8.50-8.40 (m, 2H), 8.40-8.32 (m, 2H), 7.82-7.73 (m, 1H), 7.68-7.58 (m, 2H), 7.47-7.37 (m, 2H).   13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.40, 138.88, 135.63, 132.83, 130.69, 118.56, 97.65.  phenyl(4-fluorophenyl)iodonium triflate: 165.68 (d, J = 253 Hz), 139.46 (d, J = 9.2 Hz), 136.35, 120.23 (d, J = 23.2 Hz), 115.81, 109.12 (d, J = 3.2 Hz)  triflate anion (quadruplet): 128.20, 123.95, 119.70, 115.44.  Unassigned signals (ambiguous or resulting from signal overlap): 133.41, 133.35, 132.91  Solution metathesis between phenyl(2-thienyl)iodonium and methyl 4-iodobenzoate (Table 2.6, entry d)   DCE, 80°C+2I2.16I-OTfPhOTf+PhI-OTfPh2.532.54d 2.52dI-OTfPhSIMeO2CMeO2CCO2Meratio 2.53 : 2.54d :  2.53d :  2.16          43   :   29    :   2.0   :   1.0108  Methyl 4-iodobenzoate (262 mg, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 80 °C to afford 81% (74 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.35-8.29 (m, 2H), 8.21 (dd, J = 1.2, 3.8 Hz, 1H), 8.02 (dd, J = 1.2, 5.4 Hz, 1H), 7.79-7.69 (m, 1H), 7.64-7.54 (m, 2H), 7.24 (dd, J = 1.2, 5.4 Hz, 1H).  phenyl(4-carbomethoxyphenyl)iodonium triflate: 8.46 (app d, J = 8.7 Hz, 2H), 8.38 (app d, J = 8.3Hz, 2H), 8.13-8.08 (m, 2H), 7.79-7.69 (m, 1H), 7.64-7.54 (m, 2H), 3.90 (s, 3H).   di(4-carbomethoxyphenyl)iodonium triflate: 8.51 (app d, J = 8.7 Hz, 4H), 8.13-8.07 (m, 4H), 3.90 (s, 6H). diphenyliodonium triflate: 8.35-8.29 (m, 4H), 7.79-7.69 (m, 2H), 7.64-7.54 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate]: 142.51, 138.98, 135.65, 133.41, 132.86, 130.72, 118.35, 97.22.  phenyl(4-carbomethoxyphenyl)iodonium triflate: 165.86, 136.72, 136.66, 134.49, 133.61, 133.11, 133.04, 53.01.  di(4-carbomethoxyphenyl)iodonium triflate: 165.86, 136.95, 133.20, 53.01.  diphenyliodonium triflate: 136.44.  triflate anion (two of the four lines of the quadruplet):  123.96, 119.70.  Unassigned signals (ambiguous or resulting from signal overlap): 115.32.     109  Solution metathesis between phenyl(2-thienyl)iodonium and dimethyl 5-iodoisophthalate (Table 2.6, entry e)   Dimethyl 5-iodoisophthalate (320 mg, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 63% (62 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate : 8.37-8.30 (m, 2H), 8.22 (dd, J = 1.3, 3.9 Hz, 1H), 8.03 (dd, J = 1.2, 5.4 Hz, 1H), 7.82-7.70 (m, 1H), 7.67-7.56 (m, 2H), 7.26 (dd, J = 3.8, 5.4 Hz, 1H).  phenyl(5-isophthalyl)iodonium triflate: 9.10 (app d, J = 1.5 Hz, 2H), 8.77-8.72 (m, 1H), 8.46 (app d, J = 7.5 Hz, 2H), 7.82-7.70 (m, 1H), 7.67-7.56 (m, 2H) 3.96 (s, 6H).   di(5-isophthalyl)iodonium triflate: 9.25 (app d, J = 1.4 Hz, 4H), 8.77-8.72 (m, 2H), 3.96 (s, 12H).  diphenyliodonium triflate: 8.37-8.30 (m, 4H), 7.82-7.70 (m, 2H), 7.67-7.56 (m, 4H). 13C (Me2CO-d6): 164.52, 142.52, 141.26, 140.80, 140.02, 138.99, 136.79, 136.49, 135.69, 134.58, 133.97, 133.76, 133.46, 133.12, 133.01, 132.92, 130.78, 124.07, 119.81, 118.51, 115.83, 115.44, 97.52, 53.39. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)    DCE, 80°C+2IH2.16I-OTfPh OTf+PhI-OTfPh2.532.54e2.52eI-OTfPhSIMeO2CMeO2CMeO2CCO2MeMeO2CMeO2Cratio 2.53 : 2.54e :  2.52e :  2.16          9.8  :   7.0   :   1.0   :   1.1110  Solution metathesis between phenyl(2-thienyl)iodonium and 4-iodobenzotrifluoride (Table 2.6, entry f)   4-Iodobenzotrifluoride (147 µL, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 92% (81 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.33 (d, J = 7.5 Hz, 2H), 8.22 (dd, J = 1.3, 3.9 Hz, 1H), 8.03 (dd, J = 1.3, 5.4 Hz, 1H), 7.79-7.71 (m, 1H), 7.66-7.56 (m, 2H), 7.26 (dd, J = 3.8, 5.4 Hz, 1H).  phenyl(4-trifluoromethyl)iodonium triflate: 8.58 (d, J = 8.2 Hz, 2H), 8.41 (d, J = 7.4 Hz, 2H), 7.94 (d, J = 8.4 Hz, 2H), 7.79-7.71 (m, 1H), 7.66-7.56 (m, 2H).  13C (acetone-d6): 142.49, 138.96, 137.28, 136.81, 135.66, 133.68, 133.40, 133.07, 132.85, 130.72, 129.35, 123.97, 119.71, 118.41, 115.46, 97.34. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between phenyl(2-thienyl)iodonium and 1-iodo-4-nitrobenzene (Table 2.6, entry g)   DCE, 80°CI-OTfPh2.532.54fI-OTfPhSIF3CCF3ratio 2.53 : 2.54f          12   :    1.0DCE, 80°C+2.16I-OTfPhPhI-OTfPh2.532.54gI-OTfPhSIO2NNO2ratio 2.53 : 2.54g : 2.16          3.3   :   1.0  :   tr111  1-Iodo-4-nitrobenzene (249 mg, 1.0 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (87 mg, 0.2 mmol) in 2 mL DCE and stirred for 12 h at 80 °C to afford 72% (64 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.36-8.31 (m, 2H), 8.22 (dd, J = 1.3, 3.8 Hz, 1H), 8.04 (dd, J = 1.3, 5.4 Hz, 1H), 7.83-7.71 (m, 1H), 7.68-7.57 (m, 2H), 7.27 (dd, J = 3.9, 5.4 Hz, 1H).  phenyl(4-nitrophenyl)iodonium triflate: 8.62 (app d, J = 9.2 Hz, 2H), 8.43 (app d, J = 8.4 Hz), 8.37 (app d, J = 9.2 Hz, 2H), 7.83-7.71 (m, 1H), 7.68-7.57 (m, 2H).   diphenyliodonium triflate: 8.36-8.31 (m, 4H), 7.83-7.71 (m, 2H), 7.68-7.57 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.44, 138.91, 135.65, 132.85, 130.71, 118.55, 97.61.  phenyl(4-nitrophenyl)iodonium triflate: 150.95, 137.79, 136.90, 127.15.  diphenyliodonium triflate: 136.45.  triflate anion (two of the four lines of the quadruplet): 123.97, 119.71.  Unassigned signals (ambiguous or resulting from signal overlap): 133.76, 133.38, 133.13, 132.94, 121.23, 115.82.  Solution metathesis between (mesityl)(phenyl)iodonium and 1-chloro-4-iodobenzene (Table 2.9, entry a)  DCE, 100°CI-OTfPh2.55 2.54aI-OTfPh IClClMe MeMeratio 2.55 : 2.54a         17   :   1.0112  1-Chloro-4-iodobenzene (238 mg, 1.0 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (94 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 100 °C to afford 83% (78 mg) of a mixture of products. 1H (acetone-d6): (mesityl)(phenyl)iodonium triflate: 8.08 (app d, J = 7.6 Hz, 2H), 7.82-7.67 (m, 1H), 7.67-7.52 (m, 2H).  phenyl(4-chlorophenyl)iodonium triflate: 8.39-8.33 (m, 4H), 7.82-7.67 (m, 1H), 7.67-7.52 (m, 4H).  13C (Me2CO-d6): 145.13, 143.29, 138.25, 136.51, 135.14, 133.50, 133.07, 132.97, 132.89, 131.36, 131.02, 128.32, 124.06, 121.93, 119.81, 115.55, 113.38, 112.85, 27.02, 20.92. (Signals unassigned, ratios obtained from the 1H NMR spectrum.) Solution metathesis between (mesityl)(phenyl)iodonium and 1-bromo-4-iodobenzene (Table 2.9, entry b)  1-Bromo-4-iodobenzene (283 mg, 1.0 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (94 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 100 °C to afford 80% (77 mg) of a mixture of products. 1H (acetone-d6): (mesityl)(phenyl)iodonium triflate: 8.08 (app d, J = 7.6 Hz,  2H), 7.82-7.67 (m, 1H), 7.67-7.52 (m, 2H).  phenyl(4-bromophenyl)iodonium triflate: 8.36 (app d, J = 8.6 Hz, 2H), 8.28 (app d, J = 8.7 Hz, 2H), 7.82-7.67 (m, 3H), 7.67-7.52 (m, 2H). DCE, 100°CI-OTfPh2.55 2.54aI-OTfPh IBrBrMe MeMeratio 2.55 : 2.54b         17   :   1.0113  13C (acetone-d6): 145.14, 143.30, 138.32, 136.54, 135.86, 135.15, 133.08, 132.98, 131.02, 124.06, 121.88, 119.81, 113.32, 27.02, 20.92. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  Solution metathesis between mesityl(phenyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.9, entry c)  1-Fluoro-4-iodobenzene (115 µL, 1.0 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (94 mg, 0.2 mmol) in 2 mL DCE and stirred for 24 h at 100 °C to afford 84% (79 mg) of a mixture of products. 1H (acetone-d6): (mesityl)(phenyl)iodonium triflate: 8.07 (app d, J = 7.6 Hz, 2H), 7.78-7.65 (m, 1H), 7.65-7.70 (m, 2H), 7.28 (dd, J = 3.9, 5.4 Hz, 1H).  phenyl(4-fluorophenyl)iodonium triflate: 8.43 (dd, J = 4.9, 9.1 Hz, 2H), 8.35 (app d, J = 7.6 Hz, 2H), 7.78-65 (m, 1H), 7.65-7.50 (m, 2H), 7.40 (app t, J = 8.8 Hz, 2H).  13C (acetone-d6): 145.12, 143.29, 135.14, 133.07, 132.97, 131.01, 124.06, 121.88, 119.80, 113.32, 27.02, 20.92. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  General Procedure for Microwave-Promoted Metathesis Reactions A 2-5 mL microwave glass vial (Biotage®) sealable with a metal crimp cap with septum was charged with a diaryl iodonium triflate (0.3 mmol, 1 equiv), an aryl iodide (1.5 mmol, 5 equiv.), DCE, 100°CI-OTfPh2.55 2.54aI-OTfPh IFFMe MeMeratio 2.55 : 2.54c         29   :   1.0114  and 1,2-dicholoroethane (3 mL, 0.1 M iodonium triflate concentration).  The tube was sealed (crimp cap) and submitted to microwave irradiation with a target temperature of 100 °C in high absorption mode. After the length of time indicated, the tube was retrieved and cooled to rt and the contents were concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography (gradient 10 to 50% acetone / CH2Cl2).  MW metathesis between di(2-thienyl)iodonium and 1-chloro-4-iodobenzene (Table 2.7, entry a)   1-Chloro-4-iodobenzene (358 mg, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 92% (125 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.22 (dd, J = 1.3, 3.9 Hz, 2H), 8.02 (dd, J = 1.2, 5.4 Hz, 2H), 7.25 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-chlorophenyl)iodonium triflate: 8.36 (app d, J = 8.8 Hz, 2H), 8.24 (dd, J = 1.3, 3.9 Hz, 1H), 8.06 (dd, J = 1.2, 5.4 Hz, 1H), 7.64 (app d, J = 8.8 Hz, 2H), 7.28 (dd, J = 3.8, 5.3 Hz, 1H).  di(4-chlorophenyl)iodonium triflate: 8.38 (app d, J = 8.8 Hz, 4H), 7.64 (app d, J = 8.8 Hz, 4H). MW, 100°C+2IOTf2.482.51a2.52aI-OTfSICl ClSI-OTfSClratio 2.48 : 2.51a : 2.52a        13.3 :   7.1   :   1.0115  13C (acetone-d6): 142.07, 139.52, 139.19, 138.65, 138.31, 137.48, 133.00, 132.86, 130.80, 130.46, 124.01, 119.76, 115.89, 100.83, 97.61. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between di(2-thienyl)iodonium and 1-bromo-4-iodobenzene (Table 2.7, entry b)  1-Bromo-4-iodobenzene (424 mg, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 56% (88 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.21 (dd, J = 1.3, 3.9 Hz, 2H), 8.01 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-bromophenyl)iodonium triflate: 8.27 (app d, J = 8.6 Hz, 2H), 8.24 (dd, J = 1.3, 3.9 Hz, 1H), 8.05 (dd, J = 1.3, 5.4 Hz, 1H), 7.79 (app d, J = 8.7 Hz, 2H), 7.27 (dd, J = 3.9, 5.4 Hz, 1H).  di(4-bromophenyl)iodonium triflate: 8.29 (app d, J = 8.7 Hz, 4H), 7.79 (app d, J = 8.7 Hz, 4H). 13C (acetone-d6): 142.67, 141.96, 139.13, 138.57, 138.33, 137.49, 135.88, 135.74, 130.73, 130.39, 128.00, 127.81, 123.87, 119.61, 116.73, 113.88, 100.90. (Signals unassigned, ratios obtained from the 1H NMR spectrum.) MW, 100°C+2IOTf2.482.51b2.52bI-OTfSIBr BrSI-OTfSBrratio 2.48 : 2.51b : 2.52b         1.0  :   1.3   :   1.3116  MW metathesis between di(2-thienyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.7, entry c)  1-Fluoro-4-iodobenzene (173 µL, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 55% (77 mg) of a mixture of products. 1H (acetone-d6): (2-thienyl)(4-fluorophenyl)iodonium triflate: 8.50-8.39 (m, 2H), 8.23 (dd, J = 1.3, 3.8 Hz, 1H), 8.04 (dd, J = 1.3, 5.4 Hz, 1H), 7.41 (app t, J = 8.7 Hz, 2H), 7.27 (dd, J = 3.8, 5.4 Hz, 1H). di(4-fluorophenyl)iodonium triflate: 8.50-8.39 (m, 4H), 7.41 (app t, J = 8.7 Hz, 4H). 13C (Me2CO-d6): 167.42, 164.07, 142.52, 139.50, 139.38, 139.02, 138.84, 138.72, 132.37, 131.54, 130.71, 128.20, 123.94, 120.42, 120.31, 120.11, 120.00, 119.69, 115.44, 112.17, 112.13, 109.49, 109.46, 97.80. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between di(2-thienyl)iodonium and methyl 4-iodobenzoate (Table 2.7, entry d)   MW, 100°C+2IOTf2.482.51c2.52cI-OTfSIF FSI-OTfSFratio 2.48 : 2.51c : 2.52c           0   :   1.3   :   1.32.48I-OTfSSMW, 100°CIMeO2CI-OTfS2.51dCO2Me+2IOTf2.52dMeO2Cratio 2.48 : 2.51d : 2.52d         1.5  :   1.0   :   3.3117  Methyl 4-iodobenzoate (393 mg, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 3 h at 100 °C to afford 36% (52 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.20 (dd, J = 1.3, 3.9 Hz, 2H), 8.01 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-carbomethoxyphenyl)iodonium triflate: 8.45 (app d, J = 8.7, 2H), 8.25 (dd, J = 1.3, 3.9 Hz, 1H), 8.13 (app d, J = 8.6 Hz, 2H), 8.06 (dd, J = 1.2, 5.4 Hz, 1H), 7.28 (dd, J = 3.9, 5.4 Hz, 1H), 3.92 (s, 3H).  di(4-carbomethoxyphenyl)iodonium triflate: 8.50 (app d, J = 8.7, 4H), 8.13 (app d, J = 8.6 Hz, 4H), 3.92 (s, 6H). 13C (acetone-d6): 165.86, 165.84, 142.88, 139.28, 138.52, 136.92, 136.22, 135.81, 134.64, 134.47, 133.23, 133.10, 130.84, 130.41, 128.22, 123.97, 123.05, 120.16, 119.72, 101.33, 97.88, 53.03. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between di(2-thienyl)iodonium and dimethyl 5-iodoisophthalate (Entry 5e)   Dimethyl 5-iodoisophthalate (480 mg, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 54% (85 mg) of a mixture of products. 2.48I-OTfSSMW, 100°CIMeO2CCO2MeI-OTfS2.51eMeO2C CO2Me+2IOTf2.52eMeO2CMeO2Cratio 2.48 : 2.51e : 2.52e         2.5  :   1.9   :   1.0118  1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.21 (dd, J = 1.3, 3.9 Hz, 2H), 8.01 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(5-isophthalyl)iodonium triflate: 9.10 (app d, J = 1.4, 2H), 8.78-8.73 (m, 1H), 8.33 (dd, J = 1.3, 3.9 Hz, 1H), 8.06 (dd, J = 1.3, 5.4 Hz, 1H), 7.30 (dd, J = 3.9, 5.4 Hz, 1H), 3.97 (s, 6H).  di(5-isophthalyl)iodonium triflate: 9.26 (app d, J = 1.4, 4H), 8.78-8.73 (m, 2H), 3.97 (s, 12H). 13C (acetone-d6): 164.51, 143.05, 141.98, 141.25, 140.01, 139.44, 138.59, 134.60, 134.48, 134.20, 133.90, 130.88, 130.46, 119.79, 118.85, 116.23, 115.43, 101.24, 53.40. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between di(2-thienyl)iodonium and 4-iodobenzotrifluoride (Table 2.7, entry f)   4-Iodobenzotrifluoride (220 µL, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 68% (97 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate: 8.21 (dd, J = 1.3, 3.9 Hz, 2H), 8.01 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  2.48I-OTfSSMW, 100°CIF3CI-OTfS2.51fCF3+2IOTf2.52fF3Cratio 2.48 : 2.51f : 2.52f         6.5  :   3.5  :   1.0119  (2-thienyl)(4-trifluoromethyl)iodonium triflate: 8.56 (app d, J = 8.3 Hz, 2H), 8.28 (dd, J = 1.3, 3.9 Hz, 1H), 8.07 (dd, J = 1.3, 5.4 Hz, 1H), 7.95 (app d, J = 8.7 Hz, 2H), 7.29 (dd, J = 3.9, 5.4 Hz, 1H).  di(4-trifluoromethyl)iodonium triflate: 8.64 (app d, J = 8.2 Hz, 2H), 7.95 (app d, J = 8.7 Hz, 2H). 13C (acetone-d6): 143.09, 141.97, 139.45, 138.57, 137.66, 136.46, 134.53, 134.31, 133.87, 130.85, 130.40, 129.52, 129.47, 129.42, 129.37, 129.32, 128.12, 126.07, 123.87, 122.46, 122.26, 119.62, 119.49, 101.00, 97.58. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between di(2-thienyl)iodonium and 1-iodo-4-nitrobenzene (Table 2.7, entry g)   1-Iodo-4-nitrobenzene (374 mg, 1.5 mmol) was added in a single portion to a solution of di(2-thienyl)iodonium triflate (133 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 71% (94 mg) of a mixture of products. 1H (acetone-d6): di(2-thienyl)iodonium triflate : 8.21 (dd, J = 1.3, 3.9 Hz, 2H), 8.02 (dd, J = 1.3, 5.4 Hz, 2H), 7.24 (dd, J = 3.9, 5.4 Hz, 2H).  (2-thienyl)(4-nitrophenyl)iodonium triflate: 8.60 (app d, J = 9.2 Hz, 2H), 8.38 (app d, J = 9.2 Hz, 2H), 8.30 (dd, J = 1.3, 3.9 Hz, 1H), 8.09 (dd, J = 1.3, 5.4 Hz, 1H), 7.31 (dd, J = 3.9, 5.4 Hz, 1H). 2.48I-OTfSSMW, 100°CIO2NI-OTfS2.51gNO2ratio 2.48 : 2.51g         2.6  :   1.0120  13C (acetone-d6): 150.85, 143.25, 141.93, 139.60, 138.54, 136.96, 130.88, 130.38, 127.11, 124.11, 123.86, 119.60, 101.06, 97.82. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between phenyl(2-thienyl)iodonium and 1-chloro-4-iodobenzene (Table 2.8, entry a)  1-Chloro-4-iodobenzene (358 mg, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 33% (48 mg) of a mixture of products. 1H (acetone-d6): phenyl(4-chlorophenyl)iodonium triflate: 8.41-8.32 (m, 4H), 7.81-7.73 (m, 1H), 7.68-7.57 (m, 4H).  di(4-chlorophenyl)iodonium triflate: 8.41-8.32 (m, 4H), 7.68-7.57 (m, 4H). diphenyliodonium triflate: 8.41-8.32 (m, 4H), 7.81-7.73 (m, 2H), 7.68-7.57 (m, 4H). The thienyl signals at approx. 8.24, 8.05, and 7.27 ppm more likely correspond to (2-thienyl)(4-chlorophenyl)iodonium triflate, although phenyl(2-thienyl)iodonium triflate was detected my ESI MS. 13C (acetone-d6): phenyl(4-chlorophenyl)iodonium triflate: 139.56, 138.24, 136.52, 112.75. di(4-chlorophenyl)iodonium triflate: 139.66, 138.29, 113.16.  diphenyliodonium triflate: 136.47, 115.61.  MW, 100°C+2I2.16I-OTfPhOTf+PhI-OTfPh2.532.54a2.52aI-OTfPhSIClClClratio 2.53 : 2.54a :  2.52a :  2.16          tr   :    5.0   :   6.2   :  1.0121  triflate anion (two of the four lines of the quadruplet): 124.02, 119.77.  Unassigned signals (ambiguous or resulting from signal overlap): 142.70, 139.16, 137.47, 135.68, 133.57, 133.47, 133.03, 132.99, 132.95, 132.85, 130.78.  MW metathesis between phenyl(2-thienyl)iodonium and 1-bromo-4-iodobenzene (Table 2.8, entry b)  1-Bromo-4-iodobenzene (424 mg, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 40% (63 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.39-8.32 (m, 2H), 8.25-8.21 (m, 1H), 8.07-8.03 (m, 1H), 7.84-7.72 (m, 1H), 7.66-7.58 (m, 2H), 7.30-7.25 (m, 1H).  phenyl(4-bromophenyl)iodonium triflate: 8.39-8.32 (m, 2H), 8.32-8.25 (m, 2H), 7.84-7.72 (m, 3H), 7.66-7.58 (m, 2H).   di(4-bromophenyl)iodonium triflate: 8.32-8.25 (m, 2H), 7.80-7.69 (m, 2H).  diphenyliodonium triflate: 8.39-8.32 (m, 4H), 7.80-7.69 (m, 2H), 7.63-7.55 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.45, 135.77, 133.42.  phenyl(4-bromophenyl)iodonium triflate: 138.27, 136.50, 135.87, 133.52, 127.90, 113.62.  di(4-bromophenyl)iodonium triflate: 138.34, 135.91, 128.01, 114.00.  diphenyliodonium triflate: 136.44, 115.47  MW, 100°C+2I2.16I-OTfPhOTf+PhI-OTfPh2.532.54b2.52bI-OTfPhSIBr BrBrratio 2.53 : 2.54b :  2.52b :  2.16         1.7  :   6.2   :   6.5   :   1.0122  triflate anion (two of the four lines of the quadruplet): 123.96, 119.70.  Unassigned signals (ambiguous or resulting from signal overlap): 139.09, 137.49, 135.64, 133.00, 132.95, 132.86, 130.75, 115.60.  MW metathesis between phenyl(2-thienyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.8, entry c)  1-Fluoro-4-iodobenzene (173 µL, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 77% (103 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.38-8.31 (m, 2H), 8.22 (dd, J = 1.3, 3.9 Hz, 1H), 8.04 (dd, J = 1.3, 5.4 Hz 1H), 7.80-7.72 (m, 1H), 7.65-7.57 (m, 2H), 7.27 (dd, J = 3.9, 5.4 Hz, 1H). phenyl(4-fluorophenyl)iodonium triflate: 8.47-8.39 (m, 2H), 8.38-8.31 (m, 2H), 7.80-7.72 (m, 1H), 7.65-7.57 (m, 2H), 7.45-7.36 (m, 2H).  di(4-fluorophenyl)iodonium triflate: 8.47-8.39 (m, 4H), 7.45-7.36 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.58, 139.08, 133.55, 130.84.  phenyl(4-fluorophenyl)iodonium triflate: 139.57, 139.36, 120.59, 120.29, 115.71, 108.99.  di(4-fluorophenyl)iodonium triflate: 139.44, 120.59, 120.29  triflate anion (one of the four lines of the quadruplet): 124.24.  MW, 100°C+2II-OTfPhOTf2.532.54c2.52cI-OTfPhSIFFFratio 2.53 : 2.54c :  2.52c         4.3  :   9.8   :   1.0123  Unassigned signals (ambiguous or resulting from signal overlap): 136.41, 135.71, 133.61, 133.09, 133.00.   MW metathesis between phenyl(2-thienyl)iodonium and methyl 4-iodobenzoate (Table 2.8 entry d)   Methyl 4-iodobenzoate (393 mg, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 30% (44 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.44-8.31 (m, 2H), 8.22 (dd, J = 1.3, 3.9 Hz, 1H), 8.07-8.02 (m, 1H), 7.82-7.72 (m, 1H), 7.68-7.57 (m, 2H), 7.31-7.25 (m, 1H).  phenyl(4-carbomethoxyphenyl)iodonium triflate: 8.55-8.44 (m, 2H), 8.44-8.31 (m, 2H), 8.17-8.08 (m, 2H), 7.82-7.72 (m, 1H), 7.68-7.57 (m, 2H), 3.92 (s, 3H).  (2-thienyl)(4-carbomethoxyphenyl)iodonium triflate: 8.55-8.44 (m, 2H), 8.25 (dd, J = 1.3, 3.9 Hz, 1H), 8.17-8.08 (m, 2H), 8.07-8.02 (m, 1H), 7.31-7.25 (m, 1H), 3.92 (s, 3H).  di(4-carbomethoxyphenyl)iodonium triflate: 8.55-8.44 (m, 4H), 8.17-8.08 (m, 4H), 3.92 (s, 6H).  diphenyliodonium triflate: 8.44-8.31 (m, 4H), 7.82-7.72 (m, 2H), 7.68-7.57 (m, 4H). MW, 100°C+2I2.16I-OTfPh I-OTfOTf+ +PhI-OTfPhS2.532.54d2.52d2.51dI-OTfPhSIMeO2CMeO2CCO2Me CO2Meratio 2.53 : 2.54d :  2.51d :  2.52d :  2.16         1.5  :   4.8   :   1.0   :   2.0   :   1.2124  13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.46, 134.67, 135.67, 130.75, phenyl(4-carbomethoxyphenyl)iodonium triflate: 165.86, 136.74, 136.65, 134.55, 133.16, 133.08, 53.02.  (2-thienyl)(4-carbomethoxyphenyl)iodonium triflate: 165.86, 142.88, 53.02.  di(4-carbomethoxyphenyl)iodonium triflate: 165.86, 136.93, 133.24, 53.02.  diphenyliodonium triflate: 136.47, 132.98.  triflate anion (two of the four lines of the quadruplet): 124.05, 119.79.  Unassigned signals (ambiguous or resulting from signal overlap): 139.27, 138.93, 135.82, 133.64, 133.46, 133.42, 132.89, 130.85, 120.17, 119.89, 115.51, 115.29.   MW metathesis between phenyl(2-thienyl)iodonium and dimethyl 5-iodoisophthalate (Table 2.8, entry e)   Dimethyl 5-iodoisophthalate (480 mg, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 21% (31 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.44-8.31 (m, 2H), 8.22 (dd, J = 1.3, 3.8 Hz, 1H), 8.07-7.98 (m, 1H), 7.83-7.71 (m, 1H), 7.69-7.56 (m, 2H), 7.31-7.21 (m, 1H).  phenyl(4-isophthalyl)iodonium triflate: 9.10 (app d, J = 1.5 Hz, 2H), 8.78-8.70 (m, 1H), 8.46 (app d, J = 7.4 Hz, 2H), 7.83-7.71 (m, 1H), 7.69-7.56 (m, 2H) 3.96 (s, 6H).   MW, 100°C+2I2.16I-OTfPh OTf+PhI-OTfPh2.532.54e 2.52eI-OTfPhSIMeO2CMeO2CMeO2CCO2MeMeO2CMeO2C+I2.51eMeO2CMeO2COTfSratio 2.53 : 2.54e :  2.51e :  2.52e :  2.16         3.8  :   4.0   :   1.8   :   1.0   :  1.2125  (2-thienyl)(5-isophthalyl)iodonium triflate: 9.08 (app d, J = 1.5, 2H), 8.78-8.70 (m, 1H), 8.28 (dd, J = 1.3, 3.8 Hz, 1H), 8.07-7.98 (m, 1H), 7.31-7.21 (m, 1H), 3.96 (s, 6H).  di(5-isophthalyl)iodonium triflate: 9.23 (app d, J = 1.5 Hz, 4H), 8.78-8.70 (m, 2H), 3.96 (s, 12H).  diphenyliodonium triflate: 8.39-8.30 (m, 4H), 7.83-7.71 (m, 2H), 7.69-7.56  (m, 4H). 13C (acetone-d6): 164.54, 142.80, 142.39, 141.79, 141.18, 140.76, 139.94, 139.20, 138.87, 136.76, 136.48, 135.66, 134.56, 134.41, 134.10, 133.93, 133.79, 133.72, 133.48, 133.40, 133.10, 133.01, 132.90, 130.76, 124.10, 119.84, 119.40, 118.81, 116.86, 116.14, 115.80, 115.39, 53.39. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between phenyl(2-thienyl)iodonium and 4-iodobenzotrifluoride (Table 2.8, entry f)   4-Iodobenzotrifluoride (220 µL, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 40% (59 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.38-8.31 (m, 2H), 8.22 (dd, J = 1.3, 3.8 Hz, 1H), 8.08-8.02 (m, 1H), 7.83-7.72 (m, 1H), 7.68-7.57 (m, 2H), 7.31-7.25 (m, 1H).  phenyl(4-trifluoromethyl)iodonium triflate: 8.61-8.53 (m, 2H), 8.41 (d, J = 8.5 Hz, 2H), 7.99-7.91 (m, 2H), 7.83-7.72 (m, 1H), 7.68-7.57 (m, 2H).  MW, 100°C+2I2.16I-OTfPhOTf+PhI-OTfPh2.532.54f2.52fI-OTfPhSIF3CF3CCF3I-OTfS2.51fCF3+ratio 2.53 : 2.54e :  2.51e :  2.52e :  2.16         3.8  :   4.1   :   1.3   :   1.0   :  1.2126  (2-thienyl)(4-trifluoromethyl)iodonium triflate: 8.61-8.53 (m, 2H), 8.26 (dd, J = 1.3, 3.9 Hz, 1H), 8.08-8.02 (m, 1H), 7.99-7.91 (m, 2H), 7.31-7.25 (m, 1H).  di(4-trifluoromethyl)iodonium triflate: 8.64 (app d, J = 8.2 Hz, 2H), 7.99-7.91 (m, 2H). diphenyliodonium triflate: 8.38-8.31 (m, 4H), 7.83-7.72 (m, 2H), 7.68-7.57 (m, 4H). 13C (acetone-d6): 142.96, 142.41, 139.32, 138.88, 137.64, 137.26, 136.81, 136.45, 136.04, 135.66, 134.34, 133.90, 133.68, 133.42, 133.38, 133.08, 132.96, 132.87, 130.84, 130.72, 129.53, 129.48, 129.42, 129.38, 129.32, 126.12, 123.98, 122.52, 119.73, 119.41, 118.67, 115.70, 115.47, 115.34, 97.83. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between phenyl(2-thienyl)iodonium and 1-iodo-4-nitrobenzene (Table 2.8, entry g)   1-Iodo-4-nitrobenzene (374 mg, 1.5 mmol) was added in a single portion to a solution of phenyl(2-thienyl)iodonium triflate (131 mg, 0.3 mmol) in 3 mL DCE and microwaved for 2 h at 100 °C to afford 29% (38 mg) of a mixture of products. 1H (acetone-d6): phenyl(2-thienyl)iodonium triflate: 8.38-8.31 (m, 2H), 8.24 (dd, J = 1.2, 3.8 Hz, 1H), 8.06 (dd, J = 1.2, 5.4 Hz, 1H), 7.84-7.73 (m, 1H), 7.70-7.58 (m, 2H), 7.28 (dd, J = 3.9, 5.4 Hz, 1H).  phenyl(4-nitrophenyl)iodonium triflate: 8.62 (app d, J = 9.1 Hz, 2H), 8.44 (app d, J = 7.5 Hz), 8.39 (app d, J = 7.1 Hz, 2H), 7.84-7.73 (m, 1H), 7.70-7.58 (m, 2H).   MW, 100°C+2.16I-OTfPhPhI-OTfPh2.532.54gI-OTfPhSIO2NNO2ratio 2.53 : 2.54g :  2.16         5.4  :   1.4   :   1.0127  diphenyliodonium triflate: 8.38-8.31 (m, 4H), 7.84-7.73 (m, 2H), 7.70-7.58 (m, 4H). 13C (acetone-d6): phenyl(2-thienyl)iodonium triflate: 142.58, 139.05, 135.71, 132.94, 130.80, 118.40, 97.28.  phenyl(4-nitrophenyl)iodonium triflate: 137.80, 136.97, 127.26.  diphenyliodonium triflate: 136.50, 133.49.  triflate anion (two of the four lines of the quadruplet): 124.11, 119.85.  Unassigned signals (ambiguous or resulting from signal overlap): 133.87, 133.22, 133.03, 120.98, 115.62, 115.19.  MW metathesis between (mesityl)(phenyl)iodonium and 1-chloro-4-iodobenzene (Table 2.10, entry a)   1-Chloro-4-iodobenzene (358 mg, 1.5 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (141 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 83% (118 mg) of a mixture of products. 1H (acetone-d6): (mesityl)(phenyl)iodonium triflate: 8.08 (app d, J = 7.6 Hz, 2H), 7.80-7.68 (m, 1H), 7.68-7.54 (m, 2H).  phenyl(4-chlorophenyl)iodonium triflate: 8.40-8.33 (m, 4H), 7.80-7.68 (m, 1H), 7.68-7.54 (m, 4H). MW, 100°CI-OTfPh2.55 2.54aI-OTfPh IClClMe MeMeratio 2.55 : 2.54a         11   :   1.0128  13C (acetone-d6): 145.09, 143.26, 139.43, 138.25, 136.50, 135.12, 133.48, 133.05, 132.95, 132.85, 130.99, 130.59, 128.28, 124.02, 121.92, 119.76, 115.64, 115.50, 113.33, 112.81, 27.00, 20.91. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  MW metathesis between (mesityl)(phenyl)iodonium and 1-bromo-4-iodobenzene (Table 2.10, entry b)  1-Bromo-4-iodobenzene (424 mg, 1.5 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (141 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 83% (118 mg) of a mixture of products. 1H (acetone-d6): (mesityl)(phenyl)iodonium triflate: 8.08 (app d, J = 7.5 Hz, 2H), 7.82-7.67 (m, 1H), 7.66-7.54 (m, 2H).  phenyl(4-bromophenyl)iodonium triflate: 8.36 (app d, J = 7.4 Hz, 2H), 8.32-8.26 (m, 2H), 7.82-7.67 (m, 3H), 7.66-7.54 (m, 2H).  di(4-bromophenyl)iodonium triflate: 8.32-8.26 (m, 2H), 7.82-7.67 (m, 2H).  13C (acetone-d6): 145.10, 143.27, 138.39, 138.32, 136.53, 135.87, 135.82, 135.12, 133.50, 133.06, 132.96, 130.99, 128.28, 127.99, 127.86, 124.02, 121.89, 119.76, 115.54, 113.90, 113.56, 113.30, 27.01, 20.91. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)   MW, 100°CI-OTfPh2.55 2.54bI-OTfPh IBrBrMe MeMeratio 2.55 : 2.54b  :  2.52b         33   :   5.7    :    1.0+2IOTf2.52bBr129  MW metathesis between (mesityl)(phenyl)iodonium and 1-fluoro-4-iodobenzene (Table 2.10, entry c)  1-Fluoro-4-iodobenzene (173 µL, 1.5 mmol) was added in a single portion to a solution of (mesityl)(phenyl)iodonium triflate (141 mg, 0.3 mmol) in 3 mL DCE and microwaved for 4 h at 100 °C to afford 82% (115 mg) of a mixture of products. 1H (Me2CO-d6): mesityl(phenyl)iodonium triflate: 8.08 (app d, J = 7.7 Hz, 2H), 7.80-7.68 (m, 1H), 7.66-7.53 (m, 2H).  phenyl(4-fluorophenyl)iodonium triflate: 8.44 (dd, J = 9.1, 4.9 Hz, 2H), 8.35 (app d, J = 7.6 Hz, 2H), 7.80-7.68 (m, 1H), 7.66-7.53 (m, 2H), 7.41 (app t, J = 8.8 Hz, 2H).  13C (acetone-d6): 145.07, 143.24, 139.55, 139.43, 136.36, 135.11, 133.40, 133.04, 132.94, 132.89, 130.98, 123.99, 121.90, 120.36, 120.05, 119.74, 115.70, 113.29, 27.00, 20.90. (Signals unassigned, ratios obtained from the 1H NMR spectrum.)  General Procedure for the S-Arylation of Sulfides with Iodonium Triflates A 15 mL heavy walled pressure tube sealable with a gasketed Teflon screwcap was charged with a diaryl iodonium triflate (0.1 mmol, 1 equiv), a diaryl sulfide (0.15 mmol, 1.5 equiv.), and 1,2-dicholoroethane (1 mL, 0.1 M iodonium triflate concentration). The tube was sealed (Teflon screw cap) and immersed in an oil bath maintained at 120 °C. After 15 h, the tube was retrieved MW, 100°CI-OTfPh2.55 2.54cI-OTfPh IFFMe MeMeratio 2.55 : 2.54c        5.4   :   1.0130  and cooled to rt and the contents were concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography (gradient 10 to 40% acetone/CH2Cl2).  Triphenylsulfonium Triflate (Table 3.1, entry a)  Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 38 mg (92%) of the product as an off-white solid. m.p. 133-136 °C (recr. EtOAc, lit. 135-137 °C)3 1H  (acetone-d6): 7.95-7.83 (m, 15H). 13C (acetone-d6): 135.6, 132.5, 132.2, 125.9. 19F (CDCl3): -79.09. HRMS (ESI) calcd for C18H15S+ ([M – TfO–]+): 263.0894; found 263.0895. Table 3.1, entry d: CHCl3 as solvent. 38 mg (92%) of product obtained. Same analytical data of the product obtained from the above reaction.  (4-Bromophenyl)diphenylsulfonium triflate (Table 3.2, entry a)  Ph2S (28 mg, 25 µL, 1.5 mmol) ) was added in a single portion to a solution of di(4-bromophenyl)iodonium triflate (59 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 47 mg (96%) of the product as a white solid. m.p. 106-108 °C (recr. Et2O). 1H (acetone-d6): 8.04 (app d, J = 8.9 Hz, 2H), 7.98-7.88 (m, 6H), 7.87-7.83 (m, 6H). 13C (acetone-d6): 135.8,                                                 3. Miller, R. D.; Renaldo, A. F.; Ito, H. J. Org. Chem. 1988, 53, 5571. PhSPhPh OTfPhSPh OTfBr131  135.6, 133.9, 132.6, 132.3, 130.3, 125.6, 125.3. HRMS (ESI) calcd for C18H1479BrS+   ([M – TfO–]+): 341.0000; found 341.0004.  Tris(4-bromophenyl)sulfonium triflate (Table 3.2, entry b)  Di(4-bromophenyl) sulfide (51 mg, 1.5 mmol) ) was added in a single portion to a solution of di(4-bromophenyl)iodonium triflate (59 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 51 mg (79%) of the product as a light grey solid. m.p. 182-183 °C (recr. EtOAc). 1H (acetone-d6): 8.04 (app d, J = 8.9 Hz, 6H), 7.94 (app d, J = 9.0 Hz, 6H). 13C (acetone-d6): 135.7, 134.1, 130.6, 124.8. HRMS (ESI) calcd for C18H1279Br3S+ ([M – TfO–]+): 496.8207; found 496.8210.  Di(4-methoxyphenyl)phenylsulfonium triflate (Table 3.2, entry c)  Di(4-methoxyphenyl) sulfide (37 mg, 1.5 mmol) ) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 41 mg (87%) of the product as a tan solid. m.p. 110-112 °C (recr. EtOAc). 1H (acetone-d6): 7.89-7.80 (m, 9H), 7.35 (app d, J = 9.1 Hz, 4H), 3.86 (s, 6H). 13C (acetone-d6): 165.6, 134.9, 134.3, 132.3, 131.2, 127.9, 117.9, 115.8, 56.7. HRMS (ESI) calcd for C20H19O2S+ ([M – TfO–]+): 323.1106; found 323.1111. SOTfBr3SPh OTfOMeMeO132  (4-Nitrophenyl)diphenylsulfonium triflate (Table 3.2, entry d)  (4-Nitrophenyl)phenyl sulfide (35 mg, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 39 mg (85%) of the product as a pale yellow solid. m.p. 99-102 °C (recr. Et2O). 1H (acetone-d6): 8.61 (app d, J = 9.1 Hz, 2H), 8.22 (app d, J = 8.9 Hz, 2H), 8.05 (app d, J = 8.2 Hz, 2H), 7.98 (app t, J = 7.4 Hz, 2H), 7.88 (app t, J = 7.6 Hz, 4H). 13C (acetone-d6): 136.1, 133.6, 133.1, 132.8, 132.7, 126.9, 125.1. HRMS (ESI) calcd for C18H14NO2S+ ([M – TfO–]+): 308.0745; found 308.0739.  Aryl transfer between (4-nitrophenyl)phenyliodonium triflate and Ph2S (Table 3.3, entry a)  Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of (4-nitrophenyl)phenyliodonium triflate (48 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 43 mg (100%) of a 1:2.3 mixture of (4-nitrophenyl)diphenylsulfonium triflate and triphenylsulfonium triflate. The two components were only partially resolved by chromatography. For characterization, see pure compounds above.    PhSPh OTfNO2I OTfO2NPh          Ph2Sratio 3.16a :  3.17a            1.0 : 2.3O2N SPh2 OTf + SPh2 OTf3.16a 3.17a133  Aryl transfer between (4-carbomethoxyphenyl)phenyliodonium triflate and Ph2S (Table 3.3, entry b)  Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of (4-carbomethoxyphenyl)phenyliodonium triflate (49 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 41 mg (94%) of a 1:1.9 mixture of (4-carbomethoxy- phenyl)diphenylsulfonium triflate and triphenylsulfonium triflate. The two components could not be separated by chromatography; Ph3SOTf characterization is detailed above.  (4-carbomethoxyphenyl)diphenylsulfonium triflate: 1H (acetone-d6): 8.35 (app d, J = 8.8 Hz, 2H), 8.07-7.82 (m, 12H), 3.96 (s, 3H). 13C (acetone-d6): 165.6, 135.9, 132.7, 132.6, 132.6, 132.38, 130.9, 125.4, 124.6, 53.2. HRMS (ESI) calcd for C20H17O2S+ ([M – TfO–]+): 321.0949; found 321.0944.  Aryl transfer between (4-methoxyphenyl)(4-nitrophenyl)iodonium triflate and Ph2S (Table 3.3, entry c)  and Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of (4-methoxyphenyl)(4-nitrophenyl)iodonium triflate (50 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 41 mg (92%) of a 1:1.3 mixture of (4-nitrophenyl) diphenylsulfonium triflate and (4-methoxyphenyl)diphenylsulfonium triflate. The two components were only I OTfMeO2CPhPh2Sratio 3.16b :  3.17b        1.0 : 1.9MeO2C SPh2 OTf + SPh2 OTf3.16b 3.17bI OTfO2N Ph2Sratio 3.16c :  3.17c        1.0 : 1.3O2N SPh2 OTf + SPh2 OTf3.16c 3.17cOMeMeO134  partially resolvable by chromatography. (4-nitrophenyl)diphenyl sulfonium triflate was spectroscopically identical to that obtained as detailed above. (4-methoxyphenyl)diphenylsulfonium triflate: Off-white solid. m.p. 83-85 °C (recr. Et2O). 1H (acetone-d6): 7.94-7.883 (m, 12H), 7.37 (app d, J = 9.2 Hz, 2H), 3.97 (s, 3H). 13C (acetone-d6): 165.8, 135.3, 134.8, 132.4, 131.7, 126.9, 118.0, 114.6, 56.7. HRMS (ESI) calcd for C19H17OS+ ([M – TfO–]+): 293.1000; found 293.0998.  Aryl transfer between (2-thienyl)phenyliodonium triflate and Ph2S (Table 3.3, entry d)  Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of (2-thienyl)phenyliodonium triflate (44 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 44 mg (82%) of a 1:3.8 mixture of triphenylsulfonium triflate and (2-thienyl) diphenylsulfonium triflate. The two components could not be separated by chromatography; Ph3SOTf thus produced was spectroscopically identical to that obtained as detailed above.  (2-Thienyl)diphenylsulfonium triflate: 1H (acetone-d6): 8.44 (dd, J = 5.2 Hz, 1.3 Hz, 1H), 8.27 (dd, J = 3.9 Hz, 1.3 Hz, 1H), 8.09-7.87 (m, 10H), 7.57 (dd, J = 5.2 Hz, 4.1 Hz, 1H) 13C (acetone-d6): 142.0, 140.8, 136.2, 135.5, 131.2, 128.5, 120.8, 120.2. HRMS (ESI) calcd for C16H13S2+ ([M – TfO–]+): 269.0459; found 269.0461.    I OTfPh          Ph2Sratio 3.16d :  3.17d            1.0 : 3.8SPh2 OTf + SPh2 OTf3.16d 3.17dS S135  Aryl transfer between (4-carbomethoxyphenyl)(2-thienyl)iodonium triflate and Ph2S (Table 3.3, entry e)  Ph2S (28 mg, 25 µL, 1.5 mmol) was added in a single portion to a solution of (4-carbomethoxyphenyl)(2-thienyl)iodonium triflate (49 mg, 0.1 mmol) in 1 mL DCE and stirred for 15 h at 120 °C to afford 39 mg (85%) of a 3.9:1 mixture of (4-carbomethoxyphenyl) diphenylsulfonium triflate and (2-thienyl)diphenylsulfonium triflate. The two components could not be separated by chromatography; for characterization, see above.  Aryl transfer between di(4-bromophenyl) iodonium triflate and thioanisole (Scheme 3.5)  Thioanisole (5 mg, 5 µL, 43 µmol) was added in a single portion to a solution of di(4-bromophenyl)iodonium triflate (18 mg, 30 µmol) in 0.5 mL CDCl3 in a J Young tube and immersed in an oil bath at 120 °C, while following the reaction by 1H NMR. After consumption of the iodonium (9 h), the mixture was evaporated under reduced pressure. Dissolution of the residue in minimal CH2Cl2, followed by precipitation of the sulfonium salts by dilution with n-hexanes, provided a 6.7:1 mixture of PhSMe2OTf (major component) and (4-bromophenyl)phenylmethylsulfonium triflate (minor component).  I OTf           Ph2Sratio 3.16e :  3.17e            1.0 : 3.9SPh2 OTf + SPh2 OTf3.16e 3.17eSSCO2MeMeO2CSMe I OTfBrBr+3.223.12aratio 3.23 : 3.24          1.0 : 6.7SPh MeBrOTf3.23Ph SMeMeOTf3.24+136  Phenyldimethylsulfonium triflate 3.24 (major component): 1H (CDCl3): 8.00 (d, J = 7.4 Hz, 2H), 7.76-7.68 (m, 3H), 3.38 (s, 6H). 13C (CDCl3): 135.0, 131.5, 130.0, 125.0, 29.4. HRMS (ESI) calcd for C8H11S+ ([M – TfO–]+): 139.0581; found 139.0579.  (4-Bromophenyl)phenylmethylsulfonium triflate 3.23 (minor component): 1H (CDCl3): 7.96-7.79 (m, 9H), 3.79 (s, 3H). 13C (CDCl3): 136.9, 135.5, 135.2, 132.6, 131.7, 130.1, 122.8, 118.6, 28.7. HRMS (ESI) calcd for C13H1279BrS+ ([M – TfO–]+): 278.9843; found 278.9844.  Aryl transfer between diphenyliodonium triflate and 4-bromothioanisole (Scheme 3.7)  4-Bromothioanisole (9 mg, 45 µmol) was added in a single portion to a solution of Ph2IOTf (13 mg, 30 µmol) in 0.5 mL CDCl3 in a J Young tube immersed in an oil bath at 120 °C, while following the reaction by 1H NMR. After consumption of the iodonium (31 h), the mixture was evaporated under reduced pressure. The sulfonium salts were isolated as a 1:11.2 mixture from the non-polar fraction by dissolution of the residue in minimal CH2Cl2, followed by precipitation using n-hexanes.  (4-bromophenyl)dimethylsulfonium triflate 3.27 (major component): 1H (CDCl3): 7.91 (d, J = 8.7 Hz, 2H), 7.82 (d, J = 8.6 Hz, 2H), 3.39 (s, 6H). 13C (CDCl3): 134.8, 131.5, 130.6, 123.9, 29.5. HRMS (ESI) calcd for C8H1079BrS+ ([M – TfO–]+): 216.9687; found 216.9684. (4-Bromophenyl)phenylmethylsulfonium triflate 3.23 (minor component): see characteri-zation details above. SMeBr3.38Ph2IOTfCDCl3120°CSPh MeBrOTf3.32SMe2BrOTf+MeOTf3.393.41ratio 3.32 : 3.39 : 3.41         1.0  :  9.1  :  1.8   (31h)+137  General Procedure for the Arylation of Heavy Chalcogenides with Ph2IOTf A 15 mL heavy walled pressure tube sealable with a gasketed Teflon screwcap was charged with a diaryl iodonium triflate (0.1 mmol, 1 equiv), a diphenyl selenide or telluride (0.15 mmol, 1.5 equiv.), and solvent (1 mL, 0.1 M iodonium triflate concentration). The tube was sealed (Teflon screw cap) and immersed in an oil bath maintained at 120 °C. After the time specified, the tube was retrieved and cooled to rt and the contents were concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography (gradient 10 to 40% acetone/CH2Cl2).  Triphenylselenonium Triflate (Table 3.4, entry a)  Ph2Se (35 mg, 26 µL, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL CHCl3 and stirred for 24 h at 120 °C to afford 94% (43 mg) of the product as an off-white solid. m.p. 90-93 °C (recr. Et2O). (lit. m.p. 87-89 °C, recr. CH2Cl2/Et2O).4 1H (acetone-d6): 7.87-7.75 (m, 15H). 13C (acetone-d6): 134.4, 132.4, 132.3, 128.3. 77Se (CDCl3): 492.66.5 HRMS (ESI) calcd for C18H1580Se+ [M – TfO–]+: 311.0339; found 311.0341.                                                 4. Watanabe, S.-I.; Yamamoto, K.; Itagaki, Y.; Iwamura, T.; Iwama, T.; Kataoka, T. Tetrahedron 2000, 56, 855. 5. The reference standard for this NMR spectrum was diphenyl diselenide, (PhSe)2, the 77Se nuclei of which resonate at d = 459 ppm downfield from Me2Se: Klapötke, T. M.; Krumm, B.; Polborn, K. J. Am. Chem. Soc. 2004, 126, 710. PhSePhPh OTf138  Table 3.4, entry b: Ph2Se (35 mg, 26 µL, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL DCE and stirred for 24 h at 120 °C to afford 91% (42 mg). Same analytical data of the product obtained from the above reaction.  Triphenyltelluronium Triflate (Table 3.4, entry c)  Ph2Te (42 mg, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL CHCl3 and stirred for 48 h at 120 °C to afford 14% (7 mg) of the product as an off-white solid. m.p. 148-149 °C. 1H (acetone-d6): 7.83 (app d, J = 7.7Hz, 6H), 7.79-7.65 (m, 9H). 13C (acetone-d6): 135.7, 133.5, 131.9, 124.7. 19F (acetone-d6): -79.17. 125Te (CDCl3): 757.75.6 HRMS (ESI) calcd for C18H15126Te+ [M – TfO–]+: 357.0207; found 357.0219. Table 3.4, entry d: Ph2Te (42 mg, 1.5 mmol) was added in a single portion to a solution of Ph2IOTf (43 mg, 0.1 mmol) in 1 mL DCE and stirred for 48 h at 120 °C to afford 30% (15 mg) of product obtained. Same analytical data of the product obtained from the above reaction. Presence of an impurity, presumed to be chloroethyldiphenyltelluornium triflate, [Ph2TeCH2CH2Cl]OTf: 1H (acetone-d6): 7.97 (app d, J = 8.3Hz, 4H), 7.79-7.65 (m, 6H), 4.26-4.11 (AA’BB’m, 4H). HRMS (ESI) calcd for C14H14Cl126Te+ [M – TfO–]+: 342.9817; found 342.9814.                                                 6. The reference standard for this NMR spectrum was diphenyl ditelluride, (PhTe)2, the 125Te nuclei of which resonate at d = 411 ppm, relative to external Me2Te: Köllemann, C.; Sladky, F. Organometallics, 199, 10, 2101. PhTePhPh OTf139  Table 3.4, entry e: CHCl3 as solvent; 168h. 61% (31 mg) of product obtained. Same analytical data of the product obtained from the above reaction.   140  X-ray Crystallography for Triphenyltelluronium Triflate 3.24c  Empirical Formula     C19H15O3F3STe  Formula Weight     507.97  Crystal Color, Habit     colourless, irregular  Crystal Dimensions     0.08 x 0.12 x 0.20 mm  Crystal System     monoclinic  Lattice Type      primitive  Lattice Parameters     a = 8.8281(3) Å  b = 20.8419(7) Å  c = 10.1937(4) Å  a = 90 ° b = 96.282(2)°  g = 90° V = 1864.32(10) Å3  Space Group      P 21/c (#14)  Z value      4  Dcalc       1.753 g/cm3  F000       992.00  µ(Mo-Ka)      17.53 cm-1 Diffractometer     Bruker X8 APEX II  Radiation     Mo-Ka (l = 0.71073 Å), graphite monochromated Data Images      2294 exposures @ 5.0 seconds Detector Position    39.80 mm 2qmax      60.2° No. of Reflections Measured   Total: 35485       Unique: 5454, (Rint = 0.045) Corrections     Absorption (Tmin = 0.747, Tmax = 0.869)  Lorentz-polarization Residuals (refined on F2, all data): R1; wR2 0.044; 0.061 Residuals (refined on F2): R1; wR2  0.031; 0.058 Goodness of Fit Indicator   1.04  TeOTf141  Appendix D: 1H and 13C NMR Spectra from Chapter 2 1H NMR (300 MHz, acetone-d6) for (2-mesityl)(4-nitrophenyl)iodonium triflate (2.28i-k, Table 2.3)    13C NMR (75.5 MHz, acetone-d6) for (2-mesityl)(4-nitrophenyl)iodonium triflate (2.18i, Table 2.3)   142  1H NMR (300 MHz, acetone-d6) for di(2-thienyl) iodonium triflate (2.46; Tables 2.5 and 2.6)    13C NMR (75.5 MHz, acetone-d6) for di(2-thienyl) iodonium triflate (2.36; Tables 2.5 and 2.6)    143  1H NMR (300 MHz, acetone-d6) for the melt metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry d)    13C NMR (75.5 MHz, acetone-d6) for the melt metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry d)  144  Expanded 1H NMR (300 MHz, acetone-d6) for the melt metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry d)   2.16 2.18 2.19 2.18+2.19 2.16+2.18 2.16+2.18 145  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry e)   13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry e) 146  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodotoluene (Table 2.1, entry e)  2.18 2.18 2.16 2.19 2.18+2.19 2.16+2.18 2.16+2.18 147  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-iodonaphthalene (Table 2.2, entry c)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-iodonaphthalene (Table 2.2, entry c) 148  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-iodonaphthalene (Table 2.2, entry c)   2.21a 2.22a 2.21a 2.21a 2.21a 2.22a 2.21a+2.22a 2.21a+2.22a 149  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodoanisole (Table 2.2, entry d)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodoanisole (Table 2.2, entry d) 150  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 4-iodoanisole (Table 2.2, entry d)   2.16+2.21b 2.16+2.21b 2.21b+2.22b 2.16 2.22b 2.21b 151  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-bromo-4-iodobenzene (Table 2.2, entry b)   13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-bromo-4-iodobenzene (Table 2.2, entry b) 152  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph2IOTf and 1-bromo-4-iodobenzene (Table 2.2, entry b) 2.16+2.22e 2.16+2.21e +2.22e 2.16+2.22e 2.21e+2.22e 153  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodotoluene (Table 2.3, entry i)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodotoluene (Table 2.3, entry i) 154  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodotoluene (Table 2.3, entry i)   2.27i+2.28i 2.27i+2.28i 2.27i 2.27i 155  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodoanisole (Table 2.3, entry j)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodoanisole (Table 2.3, entry j) 156  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 4-iodoanisole (Table 2.3, entry j)   2.27j+2.28j 2.27j 2.27j 2.27j+2.28j 157  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 1-iodonaphthalene (Table 2.3, entry k)    13C NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 1-iodonaphthalene (Table 2.3, entry k)  158  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)(4-nitrophenyl)iodonium triflate and 1-iodonaphthalene (Table 2.3, entry k)   2.27k 2.26k 2.28k 2.28k 2.26k+2.27k +2.28k 2.28k 2.27k 2.27k +2.28k 2.27k +2.28k 2.27k +2.28k 159  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodotoluene (Scheme 2.11)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodotoluene (Scheme 2.11) 160  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodotoluene (Scheme 2.11)  2.48+2.49 +2.50 2.48+2.49 2.48+2.49 2.49+2.50 161  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodotoluene (Scheme 2.11)  2.49 2.49 2.49 2.50 2.48 2.48 2.50 2.48 2.49 –OTf –OTf 2.49 2.50 2.49 2.48 2.49 2.49 2.50 162  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-chloro-4-iodobenzene (Table 2.5, entry a)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-chloro-4-iodobenzene (Table 2.5, entry a) 163  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-chloro-4-iodobenzene (Table 2.5, entry a)  2.48 2.48 2.48 2.51a 2.51a 2.51a 2.52a 2.51a+2.52a 2.51a 164  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-bromo-4-iodobenzene (Table 2.5, entry b)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-bromo-4-iodobenzene (Table 2.5, entry b) 165  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-bromo-4-iodobenzene (Table 2.5, entry b)  2.48 2.48 2.51b 2.51b 2.48+2.51b 2.51b+2.52b 2.51b 2.52b 166  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-fluoro-4-iodobenzene (Table 2.5, entry c)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-bromo-4-iodobenzene (Table 2.5, entry b) 167  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-fluoro-4-iodobenzene (Table 2.5, entry c)  2.48 2.48 2.48 2.51c 2.51c 2.51c 2.51c+2.52c 2.51c+2.52c 168  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.5, entry d)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.5, entry d) 169  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.5, entry d)   2.48 2.48 2.48 2.51d 2.51d 2.51d 2.51d 2.51d 170  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and dimethyl 5-iodoisophthalate (Table 2.5, entry e)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and dimethyl 5-iodoisophthalate (Table 2.5, entry e)  171  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and dimethyl 5-iodoisophthalate (Table 2.5, entry e) 2.51e 2.51e 2.51e 2.48 2.48 2.48 2.51e 2.52e 2.51e+2.52e 172  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.5, entry f)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.5, entry f)  173  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.5, entry f)2.48 2.48 2.48 2.51f 2.51f 2.51f 2.51f 2.51f 174  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.5, entry g)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.5, entry g)  175  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.5, entry g) 2.48 2.48 2.48 2.51g 2.51g 2.51g 2.51g 2.51g 141  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.6, entry a)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.6, entry a) 142  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.6, entry a)   2.53+2.51a 2.53+2.51a 2.53+2.51a 2.53+2.54a+2.52a +2.51a+2.16 2.53+2.54a+2.52a +2.51a+2.16 2.53+2.54a +2.16 143  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.6, entry a)  2.53 2.51a 2.53 –OTf –OTf –OTf –OTf 2.16 2.16 144  Expanded quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.6, entry a)  2.54a 2.52a 2.52a 2.16 2.54a 2.54a 2.16 2.16 145  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.6, entry b)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.6, entry b) 146  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.6, entry b)   2.53 2.53 2.53 2.53+2.54b +2.52b+2.16 2.53+2.54b +2.52b+2.16 2.53+2.54b +2.16 2.54b+2.52b 147  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.6, entry b)  2.53 2.16 2.53 –OTf –OTf 2.16 2.54b 2.52b 2.54b 2.52b –OTf  2.16 148  Expanded quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.6, entry b)  2.16 2.16 2.52b 2.52b 2.53 2.54b 2.54b 2.54b 149  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.6, entry c)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.6, entry c) 150  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.6, entry c)   2.53 2.53 2.53 2.54c 2.53+2.54c 2.53+2.54c 2.53+2.54c 2.54c 151  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.6, entry c)  2.53 2.53 2.53 2.54c 2.54c 2.54c –OTf –OTf 2.54c –OTf 2.53 –OTf 2.53 152  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.6, entry d)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.6, entry d) 153  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.6, entry d)   2.53 2.53 2.53 2.54d 2.54d 2.52d 2.53+2.16 2.54d+2.52d 2.53+2.54d +2.16 2.53+2.54d+ 2.52d+2.16 154  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.6, entry d)  2.53 2.53 2.53 2.53 –OTf –OTf –OTf –OTf 2.53 155  Expanded Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.6, entry d)  2.53 2.53 2.54b 2.53 2.54b 2.54b 2.53 2.52b 2.52b 2.52b 2.53 156  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.6, entry e)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.6, entry e) 157  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.6, entry e)   2.53 2.53 2.53 2.52e 2.54e 2.52e+2.54e 2.54e 2.53+2.16 2.53+2.54e +2.16 2.53+2.54e +2.16 158  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.6, entry f)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.6, entry f) 159  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.6, entry f)   2.53 2.53 2.53 2.54f 2.54f 2.53 2.54f 2.53+2.54f 2.53+2.54f 160  1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.6, entry g)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.6, entry g) 161  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.6, entry g)   2.53+2.54g +2.16 2.53+2.54g +2.16 2.53 2.53 2.53 2.54g 2.54g 2.53+2.16 162  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.6, entry g)  2.54g 2.53 2.53 –OTf –OTf –OTf –OTf 2.53 2.53 2.53 2.54g 2.16 163  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-chloro-4-iodobenzene (Table 2.9, entry a)   13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between (2-mesityl)-phenyliodonium triflate and 1-chloro-4-iodobenzene (Table 2.9, entry a) 164  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-chloro-4-iodobenzene (Table 2.9, entry a) 2.54a 2.55 2.55+2.54a 2.55+2.54a 2.55 165  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-bromo-4-iodobenzene (Table 2.9, entry b)    13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between (2-mesityl)-phenyliodonium triflate and 1-bromo-4-iodobenzene (Table 2.9, entry b) 166  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-bromo-4-iodobenzene (Table 2.9, entry b) 2.55 2.54b 2.55 2.54b 2.55 +2.54b 2.55+2.54b 167  1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-fluoro-4-iodobenzene (Table 2.9, entry c)   13C NMR (75.5 MHz, acetone-d6) for the solution metathesis between (2-mesityl)-phenyliodonium triflate and 1-fluoro-4-iodobenzene (Table 2.9, entry c) 168  Expanded 1H NMR (300 MHz, acetone-d6) for the solution metathesis between (2-mesityl)phenyliodonium triflate and 1-fluoro-4-iodobenzene (Table 2.9, entry c)  2.54c 2.55 2.55+2.54c 2.55+2.54c 2.55 2.54c 169  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-chloro-4-iodotoluene (Table 2.7, entry a)   13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-chloro-4-iodotoluene (Table 2.7, entry a) 170  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-chloro-4-iodotoluene (Table 2.7, entry a)  2.52a 2.51a 2.48 2.48 2.51a+2.52a 2.48 2.51a 2.51a 2.51a 171  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-bromo-4-iodotoluene (Table 2.7, entry b)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-bromo-4-iodotoluene (Table 2.7, entry b) 172  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-bromo-4-iodotoluene (Table 2.7, entry b)   2.51b+2.52b 2.48 2.48 2.48 2.51b 2.51b+2.52b 2.51b 2.51b 173  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-fluoro-4-iodotoluene (Table 2.7, entry c)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-fluoro-4-iodotoluene (Table 2.7, entry c) 174  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-fluoro-4-iodotoluene (Table 2.7, entry c) 2.51c 2.51c 2.51c 2.51c+2.52c 2.51c+2.52c 175  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.7, entry d)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.7, entry d) 176  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and methyl 4-iodobenzoate (Table 2.7, entry d)   2.48 2.48 2.48 2.51d 2.51d 2.51d 2.51d 2.52d 2.51d+2.52d 177  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and dimethyl 4-iodoisophthalate (Table 2.7, entry e)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and dimethyl 4-iodoisophthalate (Table 2.7, entry e) 178  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and dimethyl 4-iodoisophthalate (Table 2.7, entry e)   2.52e 2.51e 2.48 2.48 2.48 2.51e 2.51e 2.51e 2.51e+2.52e 179  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.7, entry f)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.7, entry f) 180  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 4-iodobenzotrifluoride (Table 2.7, entry f)   2.48 2.48 2.48 2.51f 2.51f 2.51f 2.51f 2.52f 2.51f+2.52f 181  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.7, entry g)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.7, entry g) 182  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Th2IOTf and 1-iodo-4-nitrobenzene (Table 2.7, entry g)   2.51g 2.51g 2.51g 2.51g 2.51g 2.48 2.48 2.48 183  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.8, entry a)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.8, entry a) 184  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.8, entry a)   2.54a+2.52a +2.51a+2.16 2.54a+2.52a +2.51a+2.16 2.54a+2.16 2.53 or 2.51a 2.53 or 2.51a 185  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.8, entry a)  –OTf –OTf –OTf –OTf 2.16 186  Expanded quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-chloro-4-iodobenzene (Table 2.8, entry a) 2.52a 2.54a 2.52a 2.54a 2.16 2.54a 187  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.8, entry b)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.8, entry b) 188  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.8, entry b)   2.53 2.53 2.53 2.53+2.54b +2.16 2.53+2.54b +2.52b+2.16 2.54b+2.52b 2.53+2.54b +2.52b+2.16 189  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.8, entry b)  –OTf –OTf –OTf –OTf 2.16 2.54b 2.52b 2.52b 2.54b 190  Expanded quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-bromo-4-iodobenzene (Table 2.8, entry b)  2.52b 2.52b 2.54b 2.54b 2.54b 2.16 2.16 2.54b 191  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.8, entry c)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.8, entry c) 192  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.8, entry c)   2.53 2.53 2.53 2.54c+2.52c 2.54c+2.53c 2.53+2.54c 2.53+2.54c 2.53+2.54c 193  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.8, entry c)  –OTf –OTf –OTf 2.53 2.54c –OTf 2.53 2.53 2.53 2.54c 2.54c 2.54c 2.52c 2.53 194  Expanded Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-fluoro-4-iodobenzene (Table 2.8, entry c)  2.54c 2.54c 2.52c 2.52c 195  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.8, entry d)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.8, entry d) 196  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.8, entry d)   2.53 2.51d 2.53+2.51d 2.53+2.51d 2.53+2.54d +2.16 2.53+2.54d +2.16 2.53+2.54d +2.16 2.54d+2.52d +2.51d 2.54d+2.52d +2.51d 197  Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.8, entry d)  2.53 2.53 2.53 2.53 –OTf –OTf –OTf 198  Expanded Quantitative 13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and methyl 4-iodobenzoate (Table 2.8, entry d)  2.52d 2.16 2.53 2.53 2.16 2.54d 2.52d 2.54d 2.54d 199  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.8, entry e)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.8, entry e) 200  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and dimethyl 5-iodoisophthalate (Table 2.8, entry e)  2.53+2.51e 2.53 +2.51e 2.53 2.51e 2.53+2.54e +2.16 2.53+2.54e +2.16 2.53+2.16 2.54e 2.54e+2.51e +2.52e 2.51e 2.54e 2.52e 201  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.8, entry f)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.8, entry f) 202  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 4-iodobenzotrifluoride (Table 2.8, entry f)   2.53+2.51f 2.53+2.51f 2.51e 2.53 2.53+2.54f +2.16 2.53+2.54f +2.16 2.54f 2.52f 2.54f+2.51f 2.54f+2.52f +2.51f 2.53 +2.16 203  1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.8, entry g)   13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.8, entry g) 204  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between Ph(Th)IOTf and 1-iodo-4-nitrobenzene (Table 2.8, entry g) 2.53 2.53 2.53 2.54g 2.54g 2.53+2.16 2.53+2.54g +2.16 2.53+2.54g +2.16 205  1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-chloro-4-benzene (Table 2.10, entry a)    13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-chloro-4-benzene (Table 2.10, entry a) 206  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-chloro-4-benzene (Table 2.10, entry a)   2.54a 2.55 2.55 2.55+2.54a 2.55+2.54a 207  1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-bromo-4-benzene (Table 2.10, entry b)   13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-bromo-4-benzene (Table 2.10, entry b) 208  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-bromo-4-benzene (Table 2.10, entry b)  2.55+2.54b 2.55 2.54b 2.54b 2.55 2.55 +2.54b 209  1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-fluoro-4-benzene (Table 2.10, entry c)   13C NMR (75.5 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-fluoro-4-benzene (Table 2.10, entry c) 210  Expanded 1H NMR (300 MHz, acetone-d6) for the MW metathesis between (2-mesityl)phenyliodonium triflate and 1-fluoro-4-benzene (Table 2.10, entry c)  2.55+2.54c 2.54c 2.54c 2.55 2.55 2.55+2.54c 211  Appendix E: 1H and 13C NMR Spectra from Chapter 3  1H NMR (300 MHz, acetone-d6) for triphenylsulfonium triflate (Table 3.1)  13C NMR (75.5 MHz, acetone-d6) for triphenylsulfonium triflate (Table 3.1)  212  19F NMR (282 MHz, acetone-d6) for triphenylsulfonium triflate (Table 3.1)    213  1H NMR (300 MHz, acetone-d6) for (4-bromophenyl)diphenylsulfonium triflate (Table 3.2)   13C NMR (75.5 MHz, acetone-d6) for (4-bromophenyl)diphenylsulfonium triflate (Table 3.2)    214  1H NMR (300 MHz, acetone-d6) for tris(4-bromophenyl)sulfonium triflate (Table 3.2)   13C NMR (75.5 MHz, acetone-d6) for tris(4-bromophenyl)sulfonium triflate (Table 3.2)    215  1H NMR (300 MHz, acetone-d6) for di(4-methoxyphenyl)phenylsulfonium triflate (Table 3.2)   13C NMR (75.5 MHz, acetone-d6) for di(4-methoxyphenyl)phenylsulfonium triflate (Table 3.2)    216  1H NMR (300 MHz, acetone-d6) for (4-nitrophenyl)diphenylsulfonium triflate (Table 3.2)   13C NMR (75.5 MHz, acetone-d6) for (4-nitrophenyl)diphenylsulfonium triflate (Table 3.2)    217  1H NMR (300 MHz, acetone-d6) for the reaction between (4-nitrophenyl)phenyliodonium triflate and Ph2S (Table 3.3, entry a)                          218  1H NMR (300 MHz, acetone-d6) for the reaction between (4-carbomethoxyphenyl)phenyl iodonium triflate and Ph2S (Table 3.3, entry b)                         219  1H NMR (300 MHz, acetone-d6) for the mixture of triphenylsulfonium triflate and (4-carbomethoxyphenyl)diphenylsulfonium triflate (Table 3.3, entry b)   13C NMR (75.5 MHz, acetone-d6) for the mixture of triphenylsulfonium triflate and (4-carbomethoxyphenyl)diphenylsulfonium triflate (Table 3.3, entry b)  220  1H NMR (300 MHz, acetone-d6) for the reaction between (4-methoxyphenyl)(4-nitrophenyl)iodonium triflate and Ph2S (Table 3.3, entry c)                         221  1H NMR (300 MHz, acetone-d6) for (4-methoxyphenyl)diphenylsulfonium triflate (Table 3.3, entry c)   13C NMR (75.5 MHz, acetone-d6) for (4-methoxyphenyl)diphenylsulfonium triflate (Table 3.3, entry c)  222  1H NMR (300 MHz, acetone-d6) for the reaction between (2-thienyl)phenyliodonium triflate and Ph2S (Table 3.3, entry d)                          223  1H NMR (300 MHz, acetone-d6) for the mixture of triphenylsulfonium triflate and (2-thienyl) diphenylsulfonium triflate (Table 3.3, entry d)   13C NMR (75.5 MHz, acetone-d6) for the mixture of triphenylsulfonium triflate and (2-thienyl) diphenylsulfonium triflate (Table 3.3, entry d)  224  1H NMR (300 MHz, acetone-d6) for the reaction between (4-carbomethoxyphenyl)(2-thienyl) iodonium triflate and Ph2S (Table 3.3, entry e)      225  1H NMR (300 MHz, CDCl3) for the reaction between di(4-bromophenyl)iodonium triflate and thioanisole (Scheme 3.5)     226  1H NMR (300 MHz, CDCl3) for the reaction between diphenyliodonium triflate and 4-bromo-thioanisole (Scheme 3.6)    227  1H NMR (300 MHz, acetone-d6) for triphenylselenonium triflate (Table 3.4, entry a)   13C NMR (75.5 MHz, acetone-d6) for triphenylselenonium triflate (Table 3.4, entry a)    228   77Se NMR (57 MHz, acetone-d6) for triphenylselenonium triflate (Table 3.4, entry a)         229  1H NMR (300 MHz, acetone-d6) for triphenyltelluronium triflate (Table 3.4, entry c)   13C NMR (75.5 MHz, acetone-d6) for triphenyltelluronium triflate (Table 3.4, entry c)    230   19F NMR (282 MHz, acetone-d6) for triphenyltelluronium triflate (Table 3.4, entry c)   125Te NMR (94 MHz, acetone-d6) for triphenyltelluronium triflate (Table 3.4, entry c)    231  1H NMR (300 MHz, acetone-d6) for triphenyltelluronium triflate contaminated with byproduct (Table 3.4 entry d)   

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