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Han, Zeyu

University of British Columbia

This thesis outlines the results from the projects undertaken as a part of my PhD studies: the synthesis of novel phosphaalkenes and the investigation of the reactivities of phosphaalkenes towards various N-heterocyclic carbenes (NHCs) or electrophiles. Chapter 1 serves as a general introduction of the properties and reactivities of phosphaalkenes, N-heterocyclic carbenes and abnormal N-heterocyclic carbenes. Chapter 2 describes the kinetic studies of the abnormal reactions between IMes with MesP=CPh₂, MesP=C(4-C₆H₄F)₂ and MesP=C(4-OMeC₆H₄)₂, respectively. The kinetic and thermodynamic data are calculated in order to compare with DFT calculations. During the study, it is noticed the abnormal reaction is catalyzed by a base whereas hindered by an acid. In Chapter 3, metathesis reactions of phosphaalkenes (MesP=CPh₂, PhP=CPh₂ and o-TolP=CPh₂) mediated by NHCs are discussed. This features the first discovery of the metathesis of a P=C bond. In addition, several novel NHC−phosphinidenes adducts are synthesized from the reactions between NHCs and PhP=CPh₂, o-TolP=CPh₂. Chapter 4 discusses the synthesis of several new phosphaalkenes. These phosphaalkenes are designed in an effort to explore the isolable monomers for the polymerization of P=C bonds. Amongst these phosphaalkenes, (TMOP)P=CPh₂, ArFP=CPh₂ and PhP=C(PhNEt₂)₂ are noticeably stable as monomers whereas PhP=C(PhOMe)₂ and PhP=CPh(PhNEt₂) dimerize as 1,2-diphosphetanes in the solid state. In Chapter 5, the novel addition reactions between various phosphaalkenes and a cationic cyclophosphine [(Lc)₄P₄]⁴⁺ (Lc = Me₂IⁱPr) to afford three-membered rings featuring a P−P bond are described. Furthermore, preliminary results regarding the conversion of the cationic cyclophosphine to potential phospha-Wittig reagents and the study of their reactivities are also presented. Finally, Chapter 6 serves to summarize this thesis work.

Text

2022-08-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/79279

Chemistry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/