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UBC Theses and Dissertations

Topics in natural product synthesis and biosynthesis Forrester, James McLeod 1972

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TOPICS IN NATURAL PRODUCT SYNTHESIS AND  BIOSYNTHESIS  by  JAMES McLEOD FORRESTER B.Sc, M.Sc,  University University  A THESIS SUBMITTED  o f E d i n b u r g h , 1967 of B r i t i s h Columbia,  1970  I N PARTIAL FULFILMENT  THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF  PHILOSOPHY  i n the•Department  We a c c e p t t h i s t h e s i s required standard  of Chemistry  as c o n f o r m i n g  to the  THE UNIVERSITY OF B R I T I S H COLUMBIA September  1972  OF  In presenting this thesis in partial  fulfilment of the requirements for  an advanced degree at the University of B r i t i s h Columbia, I agree that the Library  shall make it freely available for reference and study.  I further agree that permission for extensive copying of this  thesis  for scholarly purposes may be granted by the Head of my Department or by his representatives.  It  is understood that copying or publication  of this thesis for financial gain shall not be allowed without my written permission.  Department of  Cheml8try  The University of B r i t i s h Columbia Vancouver 8, Canada  Date  September 30 . 1972  ii  ABSTRACT In P a r t I o f t h i s t h e s i s i s d e s c r i b e d t h e s y n t h e s e s o f radiolabelled  - b i s a b o l e n e , m o n o c y c l o f a r n e s o l and f a r n e s o l - 1 0 ,11-  e p o x i d e , and the e v a l u a t i o n o f t h e i r r o l e as p r e c u r s o r s o f t h e mould m e t a b o l i t e t r i c h o t h e c i n . dehydration of r a d i o l a b e l l e d  15-Bisabolene  was p r e p a r e d by  C < - b i s a b o l o l , which i t s e l f was  p r e p a r e d by t h e a c t i o n o f "^C-methyl  magnesium i o d i d e on 2-methyl-  6-keto-6-(4'-methylcyclohex-3'-enyl)-hex-2-ene.  T h i s ketone  was p r e p a r e d i n a m o d i f i e d G r i g n a r d r e a c t i o n from 5-bromo-2-methylpent-2-ene,  ( o b t a i n e d from c y c l o p r o p y l methyl ketone by t r e a t m e n t  w i t h methyl magnesium i o d i d e f o l l o w e d by r e a c t i o n o f the i n t e r mediate  2 - c y c l o p r o p y l p r o p a n - 2 - o l w i t h 48% hydrogen bromide) and  4-methylcyclohex-3-ene  c a r b o x y l i c a c i d (prepared i n a D i e l s A l d e r  r e a c t i o n between a c r y l i c a c i d , o r i t s methyl e s t e r , and i s o p r e n e ) . M o n o c y c l o f a r n e s o l was p r e p a r e d from  ^§-ionone by r e d u c t i o n  o f the c e n t r a l double bond t o dihydro-^S -ionone f o l l o w e d by a m o d i f i e d W i t t i g r e a c t i o n w i t h r a d i o l a b e l l e d t r i m e t h y l phosphono14 a c e t a t e , p r e p a r e d from t r i m e t h y l p h o s p h i t e and 1-  C-methyl  bromoacetate. F a r n e s o l - 1 0 , 1 1 - e p o x i d e was p r e p a r e d from g e r a n i o l by f o r m a t i o n o f g e r a n y l bromide which was condensed acetoacetate.  with ethyl  H y d r o l y s i s and d e c a r b o x y l a t i o n then gave g e r a n y l  acetone which was t r e a t e d i n the same way as d i h y d r o - -ionone t o give ^ C - l a b e l l e d f a r n e s o l . 1  bromosuccinimide  Treatment  o f f a r n e s o l w i t h N-  i n aqueous glyme f o l l o w e d by base c a t a l y s e d 14 r i n g c l o s u r e gave C-labelled farnesol-10,11-epoxide.  iii  The  mechanisms whereby t h e s e  to t r i c h o t h e c i n  a r e d e s c r i b e d and  compounds c o u l d be  converted  the r e l e v a n c e , to  contemporary  r e p o r t s , of t h e i r non-incorporation i n t o t r i c h o t h e c i n i s discussed. I n P a r t I I i s d e s c r i b e d an a t t e m p t e d  s y n t h e s i s of  from 5 - a c e t o x y - 6 - m e t h y l - 2 - p - t o l y l h e p t a - l , 5 - d i e n e . p-tolualdehyde  .  f o l l o w e d by h y d r o b o r a t i o n the r e s u l t i n g reaction, o f the  Reaction  w i t h 5 - b r o m o - 2 - m e t h y l p e n t - 2 - e n e gave  methyl-6-p_-tolylhex-2-ene  alcohol,  of the double  b o n d and  and  -1-ene.  treatment  acid.  T h i s e n o l a c e t a t e c o u l d n o t be  lactone methyl  treatment  acid.  The  ,5-diene  w i t h i s o p r o p e n y l a c e t a t e and p _ - t o l u e n e s u l p f i o n i c  methanol s o l u t i o n on  Wittig  6-methyl-2-p_-tolylhept-l-ene  converted  to  In P a r t I I I i s d e s c r i b e d the photochemistry acid  of  Hydrolysis  5-one w h i c h gave 5 - a c e t o x y - 6 - m e t h y l - 2 - p _ - t o l y l h e p t a - l on  ketal  acetylation  gave, a f t e r d e k e t a l i s a t i o n  o x i d a t i o n gave  of  6-keto-2-  P r o t e c t i o n o f t h e k e t o n e as a  5-acetoxy-6-methyl-2-p-tolylhept  a c e t a t e and  <K-cuparenone  ether.  P h o t o l y s i s of t h i s  c<^cuparenone. of  triacetic  compound i n  gave 6 , 6 - d i m e t h o x y - 4 - m e t h y l - 2 - p y r o n e w h i c h  w i t h w a t e r gave c i s -|3  -carbomethyoxymethylcrotonic  mechanism f o r t h i s p r o c e s s  i s discussed.  iv  TABLE OF CONTENTS  ABSTRACT TABLE OF CONTENTS LIST OF FIGURES ACKNOWLEDGEMENTS INTRODUCTION  Page ii iv v vii 1  PART I INTRODUCTION  21  DISCUSSION  34  EXPERIMENTAL  76  BIBLIOGRAPHY  95  PART I I INTRODUCTION  100  DISCUSSION  105  EXPERIMENTAL  124  BIBLIOGRAPHY  142  PART I I I INTRODUCTION  144  DISCUSSION  153  EXPERIMENTAL  157  BIBLIOGRAPHY  160  V  L I S T OF  FIGURES  Figure  Page INTRODUCTION  I II III IV V VI VII VIII  Secondary  Metabolism  4  The i m p o r t a n t r o l e o f a c e t y l Biosynthetic  co-enzyme A  routes to mevalonic  acid  Formation o f 3-methyl 2-butenyl pyrophosphate  5 7 10  F o r m a t i o n o f g e r a n y l and f a r n e s y l phosphate  pyro-  Stereochemistry of the condensation Ct. u n i t s  10  of 13  S h i k i m i c a c i d pathway t o a r o m a t i c compounds  1.7  Acyl-polymalonate compounds  18  route to aromatic  PART I IX  XI XII  L o c a t i o n o f l a b e l s i n "o*-bisabolene 2-14c-mevalonic acid  from  25  C h a i r type f o l d i n g o f o'-bisabolene according to Ruzicka  25  Boat type f o l d i n g of Vj-bisabolene  26  Alternative X-bisabolene  27  chair  type f o l d i n g o f  XIII  Labelling pattern in trichothecin isomer (45a) o f Y - b i s a b o l e n e  from  28  XIV  Labelling pattern i n trichothecin i s o m e r (45b) o f ^ - b i s a b o l e n e  from  28  XV XVI XVII  Position of label i n trichothecin a c c o r d i n g t o H a n s o n and c o - w o r k e r s  32  Alternative  39  s y n t h e s i s of ketone  Confirmation of structure  (54)  of acid  (55)  43  vi  XvTII XIX XX XXI XXII  NMR v a l u e s f o r g e r a n i o l I n f r a r e d spectrum Nuclear magnetic trichothecin I n f r a r e d spectrum  and n e r o l  67  of t r i c h o t h e c i n  72  resonance  spectrum o f 73  of trichothecolone  N u c l e a r magnetic resonance of t r i c h o t h e c o l o n e  spectrum  74 75  PART I I I  P r e v i o u s s y n t h e s i s o f (X-cuparenone  104  PART I I I I  Acyl-polymalonate compounds  route to aromatic  II  Photochemistry  of triacetic  III  Photochemistry acid lactone  of methyl  acid  lactone  triacetic  146 151 156  vii  ACKNOWLEDGEMENTS  I would l i k e for his during the  t o D r . T. Money  i n s p i r a t i o n , g u i d a n c e a n d many h e l p f u l s u g g e s t i o n s t h e c o u r s e o f t h i s work and d u r i n g  the preparation  made of  thesis. I would also  Mr.  t o e x p r e s s my g r a t i t u d e  like  t o t h a n k D r . D. F. MacSweeney a n d  G. L. H o d g s o n f o r many i n t e r e s t i n g d i s c u s s i o n s  and h e l p f u l  suggestions. T h a n k s a r e a l s o due t o D r . P. S a l i s b u r y cultivation  of the cultures  of Trichothecium  I am g r a t e f u l t o t h e U n i v e r s i t y financial  assistance  during  f o r the capable roseum.  of B r i t i s h  the course of t h i s  Columbia f o r work.  INTRODUCTION O r g a n i c c h e m i s t s have always been i n t e r e s t e d occurring primary which  compounds,  be c l a s s i f i e d  and s e c o n d a r y m e t a b o l i t e s .  are found u n i v e r s a l l y  perform e s s e n t i a l l y are  w h i c h may  proteins  functions  and n u c l e i c a c i d s .  organisms  T h e s e compounds h a v e  and Examples  primarily  S e c o n d a r y m e t a b o l i t e s a r e more gave them t h e name " n a t u r a l  They do n o t h a v e t h e same b r o a d s p e c t r u m o f o c c u r r e n c e  as t h e p r i m a r y m e t a b o l i t e s , n o r do t h e m a j o r i t y h a v e any known b i o l o g i c a l p r o p e r t i e s w h i c h may organism,  categories  i n those organisms.  p r e s e r v e o f t h e o r g a n i c c h e m i s t who  products".  two b r o a d  P r i m a r y m e t a b o l i t e s a r e compounds  been the p r e s e r v e o f b i o c h e m i s t s . the  into  i n almost a l l l i v i n g  identical  i n naturally  function,  though  o f t h e s e compounds  some h a v e  biological  be e x h i b i t e d e n t i r e l y w i t h i n one  individual  ( e . g . h o r m o n e s ) , e x h i b i t e d b e t w e e n two o r more  u a l s o f t h e same s p e c i e s , two e n t i r e l y  different  (e.g. pheromones), or e x h i b i t e d  organisms,  individbetween  (e.g. a n t i b i o t i c s , poisons,  etc.). Three  facets  o f n a t u r a l p r o d u c t c h e m i s t r y have  f a s c i n a t e d o r g a n i c c h e m i s t s , namely the s t r u c t u r e s  particularly of the  compounds,  s y n t h e s e s o f t h e compounds,  and how  the  and more r e c e n t f a c e t o f n a t u r a l  living  cell.  A fourth,  t h e compounds a r e b u i l t up i n  product chemistry i s s o - c a l l e d biogenetic the  a c c u r a c y o f t h e t e r m " r e c e n t " may  f r o m a p a p e r p u b l i s h e d b y J..N. C o l l i e artificially imitate  produce  naturally  i n the l a b o r a t o r y  type s y n t h e s i s , though .  be j u d g e d by a q u o t a t i o n i n 1893:  occurring  "The  attempt to  s u b s t a n c e s , and t o  some o f t h e many p r o c e s s e s w h i c h a r e  p e r p e t u a l l y b e i n g c a r r i e d on a r o u n d us i n n a t u r e , has a l w a y s  been  - 2 -  one o f t h e c h i e f aims o f t h e o r g a n i c  chemist".  1  The e l u c i d a t i o n o f t h e s t r u c t u r e o f a n a t u r a l p r o d u c t i s t h e problem f i r s t  p o s e d when a new compound  into four parts: determination functional finally  determination  a total  synthesis  method o f p e r f o r m i n g degradation, obtained.  This  o f the f u n c t i o n a l groups  of the carbon s k e l e t o n  groups; determination  i s isolated.  present;  and t h e p o s i t i o n s o f t h e  of the stereochemistry;  to confirm  the s t r u c t u r a l  falls  the s t r u c t u r e .  and  The  e l u c i d a t i o n was by  classical chemical  f o l l o w e d by s y n t h e s i s o f t h e s m a l l e r f r a g m e n t s so  The modern m e t h o d i s t o u s e p h y s i c a l m e t h o d s s u c h as  i n f r a r e d , u l t r a v i o l e t , n u c l e a r m a g n e t i c r e s o n a n c e , and mass spectroscopy, obsolete  t h o u g h e v e n t h o s e modern m e t h o d s a r e b e i n g  rendered  by t h e more w i d e s p r e a d u s e o f X - r a y c r y s t a l l o g r a p h y .  Once t h e s t r u c t u r e s o f a l a r g e number o f n a t u r a l p r o d u c t s b e e n e s t a b l i s h e d i t became be c l a s s i f i e d  according  apparent that n a t u r a l products  to s t r u c t u r a l  had  could  s i m i l a r i t i e s w h i c h were  t h o u g h t t o be a c o n s e q u e n c e o f a s i m i l a r b i o s y n t h e t i c o r i g i n . Thus C o l l i e  1,2  first  c o u l d be d e r i v e d units,  to give  phenolic  suggested that c e r t a i n phenolic  compounds  from h e a d - t o - t a i l c o n d e n s a t i o n s o f a c e t i c a c i d  l i n e a r poly-^S-diketones  compounds.  This hypothesis  which could c y c l i s e  to give  has s i n c e b e e n e x t e n d e d by  3  B i r c h and Donovan. In the i s o p r e n o i d f i e l d to  4  structural  similarities  l e d Ruzicka  p o s t u l a t e h i s famous " I s o p r e n e R u l e " w h i c h s t a t e s t h a t i s o -  prenoids  a r e d e r i v e d by h e a d - t o - t a i l c o n d e n s a t i o n  (1) u n i t s .  of  isoprene  - 3 -  CD In the a l k a l o i d  field  i t was  realised  early  t h a t , f o r e x a m p l e , d i h y d r o x y p h e n y l a l a n i n e (2) i n v o l v e d i n the b i o s y n t h e s i s of c e r t a i n e.g.  laudanosine  i n this  was  century  probably  isoquinoline  alkaloids,  (3).  (3) (2)  Practically from  relatively  types.  s i m p l e s t a r t i n g m a t e r i a l s by way  Natural products  w h i c h may which  the whole v a s t a r r a y of n a t u r a l p r o d u c t s  be  are the p r o d u c t s  o f a few  of secondary  shown s c h e m a t i c a l l y i n F i g u r e I .  The  arises reaction  metabolism  carbohydrates  are i m p o r t a n t i n t h i s pathway are monosaccharides  which  are  -  f i r s t converted A  4 -  t o p y r u v i c a c i d (4) and then t o a c e t y l co-enzyme  (5).  C0  2  h-o chlorophyll  + H 0 2  Carbohydrates Carbohydrate Metabolism V  via enzymatically Complex n a t u r a l controlled products of ^r r e a c t i o n s every type -  Pool of simple o r g a n i c compounds  -  F i g u r e I : Secondary M e t a b o l i s m 0  CH.  II  C  C0 H 2  (4)  A c e t y l co-enzyme A i s p r o b a b l y  the most i m p o r t a n t  mediate i n the b i o s y n t h e s i s o f n a t u r a l p r o d u c t s intermediate  as i t i s a common  on the pathway t o a l l t h r e e o f the main groups o f  natural products, compounds.  inter-  the i s o p r e n o i d s , the a l k a l o i d s and the a r o m a t i c  The i m p o r t a n t  r o l e o f a c e t y l co-enzyme A ( 5 ) i s  shown s c h e m a t i c a l l y i n F i g u r e I I . The b i o s y n t h e s i s o f t e r p e n e s has r e c e n t l y been r e v i e w e d and a t p r e s e n t biochemical  i s thought t o p r o c e e d as f o l l o w s .  6,7  The i n i t i a l  r e a c t i o n i n t e r p e n o i d b i o s y n t h e s i s i s the enzymic  reduction of (S)-3-hydroxy-3-methylg]utaryl  co-enzyme A (6) t o  produce ( R ) - m e v a l o n i c a c i d ( 7 ) . the r e d u c t i o n o c c u r r i n g by two hydrogen t r a n s f e r s from reduced n i c o t i n a m i d e - a d e n i n e phosphate (8a) (NADPH).  dinucleotide  The o x i d i s e d form o f NADPH i s NADP C8b) +  - 5 Linear condensation  Branched condensation  A c e t y l Co-Enzyme A  Krebs cycle F a t t y a c i d s and A r o m a t i c compounds, e.g. A n t h r a q u i n o n e s , Tetracyclines etc.  Amino  Acids  Mevalonic  Alkaloids Figure  II:  Acid  Isoprenoids  The i m p o r t a n t r o l e o£ a c e t y l co-enzyme A  fj  0  OH CH,  W  I  I  II  3  0  U  C H C - S - C H C H N H C O ( C H ) NHCOCH-C-CH -0-P-0-P-OH 3  2  2  2  2  CH.  OH  HO —  (5)  As  f a r as i s known a t p r e s e n t ,  this  P  i s t h e o n l y method by  w h i c h m e v a l o n i c a c i d i s p r o d u c e d and m e v a l o n i c a c i d i s used in terpenoid  biosynthesis.  number o f p a t h w a y s . glutaconic  ester  (9)  Ester  (6),  only  however, i s a p r o d u c t o f a  I t c a n be p r o d u c e d by e n z y m i c h y d r a t i o n o f which  i s a product of b i o t i n  dependent  - 6 -  H  H  c a r b o x y l a t i o n o f 3 - m e t h y l c r o t o n y l co-enzyme A (.10) > a d e g r a d a t i o n product of leucine. ester  A b i o l o g i c a l l y more i m p o r t a n t p a t h w a y t o  (6) i s t h e c o n d e n s a t i o n o f a c e t y l  co-enzyme A (5) w i t h  g  acetoacetyl  co-enzyme A ( 1 1 ) .  A c e t o a c e t y l co-enzyme A (11) c a n  be s y n t h e s i s e d e i t h e r b y c o n d e n s a t i o n o f two m o l e c u l e s co-enzyme A  (5) o r by d e g r a d a t i o n o f f a t t y  summarises the s y n t h e s i s o f m e v a l o n i c Thus m e v a l o n i c  acids.  of a c e t y l  Figure I I I  acid (7).  a c i d c a n be s y n t h e s i s e d f r o m t h r e e m o l e c u l e s  of a c e t i c acid since there e x i s t s  an enzyme f o r e s t e r i f y i n g  acetic  -  Carbohydrate  7  -  Fat  • Protein  (7)  Figure  acid with any  I I I : Biosynthetic  co-enzyme A.  other precursor  chemically  routes to mevalonic  M e v a l o n i c a c i d has b e e n u s e d more  i n terpene b i o s y n t h e t i c  s t a b l e , c a n be s y n t h e s i s e d  ways d e p e n d i n g on t h e l a b e l l i n g i s n o t known t o be u t i l i s e d biosynthesis.  acid  studies  than  because i t i s  i n at least eleven d i f f e r e n t  r e q u i r e m e n t s , a n d most  f o r anything other than  importantly,  terpene  O n l y t h e (R)-£orm o f m e v a l o n i c a c i d i s b i o l o g i c a l l y 9  active, since to  the (S)-form being m e t a b o l i c a l l y  synthetic mevalonic acid i s usually  resolve.  inert.  This  i s fortunate  r a c e m i c and i s d i f f i c u l t  -  The  n e x t two  8  -  steps i n the b i o s y n t h e s i s  of t e r p e n o i d s are  both p h o s p h o r y l a t i o n s , which produce mevalonic  acid-5-phosphate  (12) and m e v a l o n i c a c i d - 5 - p y r o p h o s p h a t e ( 1 3 ) .  The  group of  donated i n each r e a c t i o n  adenosine triphosphate  especially  i s the t e r m i n a l phosphate (ATP).  The  enzymes  group  responsible,  t h e one p r o d u c i n g t h e m o n o p h o s p h a t e , w h i c h i s t h e  which only u t i l i s e s from y e a s t  (14)  phosphate  10,12  (R)-mevalonic a c i d , " ^ ' " ^  , . and f r o m  liver.  have been p u r i f i e d  13,14  (7)  (12) ATP ADP CH  (13)  NH  (14)  OH  one  OH  - 9 The n e x t  step i n terpenoid b i o s y n t h e s i s i s a c t u a l l y  degradation.  Mevalonic  i c a l l y w i t h adenosine diphosphate  (ADP),  acid-5-pyrophosphate  (13) r e a c t s ' enzymat-  t r i p h o s p h a t e (14) t o g i v e  i n o r g a n i c phosphate,  a  carbon  adenosine d i o x i d e and  3-methyl-  12 3-butenyl pyrophosphate  (15)  (synonym i s o p e n t e n y l p y r o p h o s p h a t e ) .  The o x y g e n o f t h e t e r t i a r y h y d r o x y l g r o u p inorganic phosphate, first  1 5  ends up i n t h e  s u g g e s t i n g t h a t t h i s h y d r o x y l group i s  p h o s p h o r y l a t e d , b u t no i n t e r m e d i a t e p h o s p h a t e h a s b e e n  isolated.  The d o u b l e b o n d must be f o r m e d by a c o n c e r t e d  elimination,  and n o t b y a d e h y d r a t i o n f o l l o w e d b y d e c a r b o x y l a t i o n , b e c a u s e no hydrogen from process  t h e aqueous medium a p p e a r s  i s a trans elimination"^  not been found analogous carbon  elsewhere  i n the product.  and t h i s  The  t y p e o f r e a c t i o n has  i n enzyme c h e m i s t r y , t h o u g h i t i s  t o some o r g a n i c r e a c t i o n s , e.g. t h e e l i m i n a t i o n o f  d i o x i d e and h a l i d e  i o n from  the s a l t s  of 3-halogenopropionic  acids. 3-Methyl-3-butenyl 3-methyl-2-butenyl pyrophosphate) reversible partially  pyrophosphate  pyrophosphate  (15) i s n e x t c o n v e r t e d  (16) (synonym 3 , 3 - d i m e t h y l  v i a a prototropic shift.  into allyl  T h i s i s one o f t h e few  r e a c t i o n s i n t e r p e n o i d b i o s y n t h e s i s and s t u d i e s w i t h 17 18 purified  equilibrium  lies  enzyme f r o m y e a s t o r l i v e r  rather heavily  t h e p r o t o n on g o i n g f r o m  towards  show  '  t h a t the  ( 1 6 ) . The e l i m i n a t i o n o f  (15) t o (16) i s s t e r e o s p e c i f i c ,  t h e one  e l i m i n a t e d b e i n g Ha as shown i n F i g u r e I V . The c h e m i c a l s i g n i f i c a n c e a substance nucleophilic  with a relatively double  o f t h e change  (15)-*(16) i s t h a t  unreactive phosphoryl  bond, i s c o n v e r t e d i n t o a h i g h l y  g r o u p and a reactive  - 10 ATP  CH-OH  HO  ADP  CHOP0H 2  CH2OP 2n 6H, 3  He  2 6 3  He Hd Ha Hb  Pi  (13)  Ha Hb  CO.  (15)  H H;  CH.  CH. 2OP.2OJo-3L  Hb  (16) Figure  I V : F o r m a t i o n o f 3-methyl-2-butenyl  (16)  Pyrophosphate  OP206H3  H  +  OP0,H 263 (15) ?  U  N  O.P0H  2 6 3  cm  HH H ^SJ OP^O.H 26 3 +  2°63  P  (18) F i g u r e V:  Formation of geranyl  and f a r n e s y l  pyrophosphates  H  - 11 -  electrophilic The  allyl  pyrophosphate.  intermediates  (15) and  (16) a r e n e x t j o i n e d  as shown i n F i g u r e V, by an enzyme c a l l e d a p r e n y l This  r e a c t i o n resembles  considered species.  a polymerisation i n that  as t h e i n i t i a t i n g The  i o n f r o m one  and  and a h y d r o g e n (17).  This  analagous, r e a c t i o n with  (16) can  replace  be  propagating  w i t h loss of  i o n from the o t h e r  c a n now  transferase.  (15) as t h e  two m o l e c u l e s a r e c o m b i n e d  pyrophosphate  (18).  species  together,  pyrophosphate  to form  geranyl  (16) i n a f u r t h e r ,  (15) t o g i v e f a r n e s y l p y r o p h o s p h a t e  1 9  It  i s now  pyrophosphate phate)  t h o u g h t t h a t most m o n o t e r p e n e s a r i s e (17)  ( o r i t s c i s - d o u b l e bond isomer n e r y l  and t h a t most s e s q u i t e r p e n e s  phosphate  (18)  from  arise  20 Isoprene Rule".  pyrophos-  from f a r n e s y l pyro-  (or i t s c i s - d o u b l e bond i s o m e r ) .  ment o f t h e " B i o g e n e t i c  geranyl  This  i s a state-  21 ' 19 22  The  t r a n s f e r a s e from l i v e r has been p a r t i a l l y p u r i f i e d  and t h e r e  i s no i n d i c a t i o n  the  two  was  incapable  of  steps  units,  accommodate the  l e a d i n g t o (17) and of using  (18).  preparation  for further addition  t h e s t r u c t u r e o f t h e enzyme  (17) b u t does n o t h a v e s p a c e  a s s o c i a t i o n of  an e n z y m i c p r o c e s s , bonds i n n a t u r e in effect  can  t o accommodate  formation  are of the a l d o l  of " d i - i s o b u t e n e "  (15).  u n i t s i s an u n u s u a l r e a c t i o n e v e n f o r  as most c o n d e n s a t i o n s t o f o r m  an a l k y l a t i o n  '  enzymes c a t a l y s e  However t h i s  (18) as a s u b s t r a t e  thus presumably (16) and  different  l a r g e r (18) i n a c o n f i g u r a t i o n r e q u i r e d f o r r e a c t i o n w i t h This  is  t h a t two  '  23  or C l a i s e n type.  o f an o l e f i n (19) f r o m  and  carbon-carbon This  i s analogous  isobutene:-  reaction t o the  12  -  CH •>  (CH ) C 3  +  3  CH  H  CH CH  -H  +  >  (CH ) C-CH -C 3  3  /  2  (19)  This  e n z y m i c r e a c t i o n was  at f i r s t  carbonium i o n r e a c t i o n of s i m i l a r  considered  type, but  t o be  experiments  a using  a s y m m e t r i c l a b e l l i n g w i t h h y d r o g e n i s o t o p e s h a v e shown t h a t formation  of the  c a r b o n - c a r b o n b o n d i s a c c o m p a n i e d by  i n v e r s i o n o f c o n f i g u r a t i o n at the characteristic  in  allylic two  C^  stages:  unit  a carbonium i o n r e a c t i o n .  16  and  firstly  o f an e l e c t r o n d o n a t i n g e l i m i n a t i o n o f X and If be  condensation polyterpene eliminations  and  This i s  this  o f C$ rubber. can be  The  a d d i t i o n of  e l i m i n a t i o n of the hydrogen i o n  a t r a n s a d d i t i o n of the g r o u p X,  f o l l o w e d by  allylic  subsequent  24  occur  unit  and  trans  o f h y d r o g e n i o n (H ) as shown i n F i g u r e  Hd w e r e e l i m i n a t e d , t h e  obtained  c a r b o n atom.  of a b i m o l e c u l a r n u c l e o p h i l i c s u b s t i t u t i o n  r e a c t i o n r a t h e r than the  allylic  complete  alternative  corresponding  VI.  c i s isomer would pathway f o r  the  u n i t s i s i n v o l v e d i n the b i o s y n t h e s i s of  the  The  stereochemical  stereochemical  f o l l c i v e d by  feeding  f a t e o f the  hydrogen  2R- 2D, - m e v a l o n a t e  and  - 13  -  H  Figure VI:  Stereochemistry  of the Condensation  2S-2Dj,-mevalonate f o l l o w e d by o f h y d r o g e n and isopentenyl  deuterium  of C  5  units  d e t e r m i n a t i o n of the s t e r i c p o s i t i o n s  i n i s o p e n t e n o l o b t a i n e d from  pyrophosphate. ^ 1  the  - 14 -  Geranylgeranyl pyrophosphate diterpenes,  i s formed by a n o t h e r  pyrophosphate  ( 2 0 ) , the p r o g e n i t o r of the a d d i t i o n o f (15) t o f a r n e s y l  ( 1 8 ) , a n d t h e f r e e h y d r o x y compound has r e c e n t l y  25 b e e n shown (21).  t o be a p r e c u r s o r o f t h e d i t e r p e n e  A d d i t i o n of y e t another  unit gives 26  pyrophosphate  (22) w h i c h h a s b e e n shown  the b i o s y n t h e s i s o f t h e s e s t e r p e n e  geranylfarnesy1  ' t o be i m p l i c a t e d i n  o p h i o b o l i n F (23) by  free extracts of Chochliobolus heterostrophus. ( 2 2 , OH i n s t e a d o f 0?2^^^)  rosenonolactone  cell  Geranylfarnesol  has r e c e n t l y been f o u n d  i n insect  27 wax.  0P 0,H. 2 6 j o  (20)  O P  C22)  2°6 3 H  - 15 -  Triterpenes  ( C 3 0 ) are not b i o s y n t h e s i s e d  from the C ^ Q analogue  of  (22) b u t a r e i n s t e a d formed from t h e s y m m e t r i c a l h y d r o c a r b o n 28 squalene (24). T h i s compound i s d e r i v e d f r o m " t a i l - t o - t a i l " condensation its  o f two m o l e c u l e s o f f a r n e s y l p y r o p h o s p h a t e  b i o s y n t h e s i s and c o n v e r s i o n  been t h e s u b j e c t  t o t r i t e r p e n e s and s t e r o i d s have  of considerable  w h i c h have been d e s c r i b e d  (18) a n d  i n v e s t i g a t i o n , the r e s u l t s of 6,24,29 i n several e x c e l l e n t reviews.  (24)  He  - 16 J u s t as t h e r e a l i s a t i o n in  o f the importance  t h e b i o s y n t h e s i s o f t e r p e n o i d s has p r o v e d  elucidation types  of isoprene units  i n v a l u a b l e i n the  and c o r r e l a t i o n o f t h e l a r g e v a r i e t y  characteristic of this  of the importance  of structural  c l a s s o f compound, s o t h e r e a l i s a t i o n  o f o t h e r compounds i n t h e b i o s y n t h e s i s o f n o n -  i s o p r e n o i d compounds h a s l e d t o g r e a t e r u n d e r s t a n d i n g chemistry  o f these  compounds.  One s u c h  class referred to c o l l e c t i v e l y compounds c a n a r i s e  i n nature  termed the s h i k i m i c a c i d glucose metabolism, in  i n two d i s t i n c t w a y s .  These One r o u t e i s  (25) r o u t e , w h i c h i s an o f f - s h o o t o f  to aromatic  12 3 5 ' ' ' now c a l l e d 1,2 by C o l l i e ,  acetic acid of malonyl  The s h i k i m i c a c i d p a t h w a y i s  route  route.  As  originally  i n v o l v e d condensations  of  u n i t s , b u t more r e c e n t work^O has shown t h e co-enzyme A  ( 2 6 ) as a p r e c u r s o r o f t h e c h a i n  at present  the features of t h i s  importance propagating  r o u t e a r e as  A c e t y l co-enzyme A (5) ( t h e c h a i n s t a r t e r u n i t ) c o n d e n s e s  w i t h enzyme b o u n d m a l o n i c formed from malonyl  acid  co-enzyme A  co-enzyme A (26) i t s e l f by b i o t i n  compounds i s t h e a c e t a t e  the acyl-polymalonate this  As u n d e r s t o o d  follows.  (27) ( t h e c h a i n p r o p a g a t i n g (26) by e s t e r e x c h a n g e .  i s d e r i v e d from a c e t y l  dependent c a r b o x y l a t i o n .  The p r o d u c t  VIII.  Malonyl  from t h e conden-  ( 2 7 ) t o g i v e an enzyme b o u n d p o l y - y g - d i k e t o n e  shown i n F i g u r e  unit),  co-enzyme A (5)  s a t i o n c a n now r e a c t s e q u e n t i a l l y w i t h more enzyme b o u n d acid  important  summarised i n F i g u r e V I I .  envisaged  unit.  compounds.  compounds f o r m e d b y t h i s m e t h o d b e i n g  The o t h e r r o u t e route,  g r o u p o f compounds i s t h e  as a r o m a t i c  the b i o s y n t h e s i s of a l k a l o i d s .  briefly  of the  chain  malonic ( 2 8 ) as  -  Phosphoenol  S-dehydroquinic  Figure V I I :  -  Pyruvate  acid  5-dehydroshikimic  Phenylalanine  17  acid  Shikimic acid  £25)  HO-C  Tyrosine S h i k i m i c a c i d pathway t o a r o m a t i c  compounds  OPOJ  -  18  -  CH COSCoA 3  (5)  Biotin/ATP/Mg /HC0 + +  3  CH COSCoA 2  C0 H 2  (26)  Enzyme  CH -CO-S-Enzyme + CH CO SCoA 3  C0 H 2  (27)  1  C H C O C H CO-S-Enzyme  CH^CO-S-Enzyme  (repeated n times)  C0 H 2  CH C O ( C H C O ) C H C O - S - E n z y m e 2  n  2  (28) (n = 1-8) Figure VIII:  Acyl-polymalonate  route to aromatic  compounds  - 19 -  The p o l y - ^ S - d i k e t o n e c h a i n c a n now u n d e r g o i n t e r n a l c y c l i s a t i o n w h i c h c a n be o f two t y p e s , n a m e l y a l d o l c o n d e n s a t i o n t o g i v e orsellinic give  acid  ( 2 9 ) t y p e compounds,  acyl phloroglucinols,  or C l a i s e n  condensation to  e.g. a c e t y l p h l o r o g l u c i n o l  (30).  0  Enzyme-S-OC  1  (28,n=l)  1—»6  2—»7  Aldol ClaisenN  OH  H0 0 2  (29) OH  A number to  (30) of secondary m o d i f i c a t i o n s  c y c l i s a t i o n or a f t e r c y c l i s a t i o n .  e.g. (32).  mycophenolic acid reduction,  halogenation, ring,  prior  alkylations,  31 32 33 (31), ' ' oxidation,  introduction acid  of nitrogen, (34)  38  F u r t h e r w o r k on t h i s r o u t e that  These i n c l u d e  e.g. 6 - m e t h y l s a l i c y l i c  e.g. p e n i c i l l i c  can o c c u r , e i t h e r  e.g. f u m i g a t i n 30,34,35,36,37 acid (33),  and c l e a v a g e o f t h e a r o m a t i c  and p a t u l i n ( 3 5 ) .  39,40  t o a r o m a t i c compounds  acetic  acid  i s not the only  acid  involved  Other acids  also  f o u n d as s t a r t e r u n i t s  include  has  revealed  as a s t a r t e r cinnamic  unit.  acids.  20  -  0  OH H0 C 2  OCH 0  (31)  (32)  OH  OCH.  ° ^ H  (33)  benzoic  acids,  are p r o d u c t s  (35)  nicotinic  acid  of the s h i k i m i c  and a n t h r a n i l i c a c i d . acid  (25) r o u t e  so compounds f o r m e d by u t i l i s a t i o n a confluence  o f t h e two r o u t e s .  compounds h a v i n g  such p i n o s y l v i n ( 3 7 ) . 42  to aromatic  o f one o f t h o s e  Representative  a mixed b i o g e n e s i s  These a c i d s  acids  represent  examples o f  are yangonin  41 (36) and  OCH.  (36)  compounds  (37)  PART I  INVESTIGATIONS OF TRICHOTHECIN  BIOSYNTHESIS  - 21 INTRODUCTION Structural Elucidation The b i o l o g i c a l  o f T r i c h o t h e c i n (38)  activity  o f T r i c h o t h e c i u m roseum L i n k has been 43  r e p o r t e d s e v e r a l times  s i n c e the beginning of t h i s 44  I n 1949 Freeman and M o r r i s o n properties  r e p o r t e d t h e i s o l a t i o n and  o f t h e compound r e s p o n s i b l e f o r t h e b i o l o g i c a l  and named i t t r i c h o t h e c i n . trichothecin: C^^H^qO^;  century.  Their results  (a) h a s a m o l e c u l a r  indicated  activity,  that  f o r m u l a o f C-| qH-j, gO^ o r  (b) i s a n e u t r a l , u n s a t u r a t e d ,  conjugated  ketone,  con-  t a i n i n g no h y d r o x y l o r a l k o x y l g r o u p a n d , ( c ) h a s t h r e e C - m e t h y l groups. ^19^24* 5 J  Later work^ a n c l  t  5  showed t h a t t h e m o l e c u l a r  ^ ^ t r i c h o t h e c i n was an e s t e r , i a  f o r m u l a was  t h e components  o f w h i c h w e r e t r i c h o t h e c o l o n e ( 3 9 ) and i s o c r o t o n i c 0  acid.  22  -  I n 1959 basis  structure  of a s y s t e m a t i c  the p o s s i b i l i t y  (40)  was  -  proposed  degradation,  (40)  was  were a l s o the  first  provided  by  f o r t r i c h o t h e c i n on  w h i c h , however, d i d not  of a l t e r n a t i v e s t r u c t u r e  for structure  46  (41).  J o n e s and  Further  the  exclude  evidence  his co-worlcers,  4 7  who  48  I n 1964 isolated  49  acetate,  confirmed  suggesting  s t r u c t u r e was  by  The  o x i d a t i o n of t r i c h o d e r m i n (42)  trichodermol was  To  resolve  with  some o f t h e  trichothecolone However  r e a c t i o n s of  in of  p_-bromobenzoate (43,p_-bromobenzoate i n s t e a d o f  of trichodermin  of t r i c h o t h e c i n .  and  hence  (3S)  structure i s the  (43)  is  correct  this  trichodermin,  epoxide r i n g  t h i s p r o b l e m an X - r a y a n a l y s i s  u n d e r t a k e n , ^ which i n d i c a t e d that  structure  spectral  and  to  for trichodermin.  r e a c t i o n s w h i c h s u g g e s t e d t h e p r e s e n c e o f an trichodermin.  chemical  was  suggested a r e l a t i o n s h i p to t r i c h o t h e c i n ,  structure  incompatible  of t r i c h o t h e c i n .  named t r i c h o d e r m i n ,  of Trichoderma.  of t r i c h o d e r m i n  t h i s was  the b i o s y n t h e s i s  compound, w h i c h was  from a s t r a i n  properties and  a new  to study  acetyl)  the structure  23 -  (42)  Biosynthetic Proposals  for Trichothecin  48 J o n e s and Low trichothecin  (38).  were the f i r s t  the b i o s y n t h e s i s of  In d e r i v i n g the t r i c h o t h e c i n carbon  from f a r n e s y l pyrophosphate  skeleton  (18) ( a s r e q u i r e d b y t h e " B i o g e n e t i c  20 21 Isoprene Rule"' ' ) i t i s necessary migration  to study  to i n v o k e  o r two 1 , 2 - m e t h y l m i g r a t i o n s .  The  e i t h e r a 1,3-methyl  r e s u l t s o f J o n e s and  48 Lowe  showed t h a t two 1 , 2 - m e t h y l m i g r a t i o n s Using  synthesis  e r r o n e o u s s t r u c t u r e (40.) R u z i c k a of t r i c h o t h e c i n .  He p r o p o s e d  occur. discussed, the b i o -  that f a r n e s y l pyrophosphate  - 24 -  (18) c y c l i s e s  to g i v e carbonium  p r o t o n t o form 'o'-bisabolene a r e two stated^  i o n (44) which, t h e n l o s e s  (45) .  I t s h o u l d be n o t e d t h a t t h e r e  i s o m e r s o f ' b ' - b i s a b o l e n e (45a) and 1  (45b).  R u z i c k a has  t h a t s t a r t i n g w i t h ( 2 - ^ C ) - m e v a l o n i c a c i d the  p a t t e r n s h o u l d be  labelling  as shown i n F i g u r e I X and t h a t b o t h i s o m e r s  'o'-bisabolene c a n be  (18)  a  d e r i v e d from f a r n e s y l pyrophosphate  (44)  of  (18) , w h e t h e r  (45)  - 25 or not  one  s t a r t s with, a c i s o r a t r a n s c e n t r a l double bond.  R u z i c k a has and  a l s o stated ''" t h a t b o t h ^ - b i s a b o l e n e s 5  u n d e r g o two  stereochemistry i n F i g u r e X. A  1,2-methyl m i g r a t i o n s of t r i c h o t h e c i n  According  to the  could  cyclise  to g i v e the s t r u c t u r e  and  (as assumed a t t h a t t i m e ) as labelling  s t u d i e s of Jones  shown  and  O  Lowe which  i t i s the  t r a n s m e t h y l group i n the  i s o p r o p y l i d e n e group  migrates.  14. (45a) Figure  IX:  (45b)  Location of l a b e l acid  C45  a or  Figure  X:  C h a i r type  from 2- C _ 14  mevalonic .  b)  4_  (40)  in ^-bisabolene  <-  OR folding  of X-bisabolene according  to  Ruzicka  -  26  -  H o w e v e r , when t h e c o r r e c t s t r u c t u r e  C38) i s t a k e n i n t o  account  t h i s m e c h a n i s m g i v e s t h e w r o n g s t e r e o c h e m i s t r y i n t h e 5-membered  49b ring.  Two a l t e r n a t i v e m e c h a n i s m s  invoking a boat-type scheme  c a n be c r i t i c i s e d  boat-type  folding  type f o l d i n g , to  folding  are p o s s i b l e ,  the f i r s t  o f the side c h a i n CFigure X I ) .  on a t l e a s t two c o u n t s .  This .  F i r s t l y the  i s more e n e r g e t i c a l l y u n f a v o u r a b l e t h a n a c h a i r -  and s e c o n d l y t h e m e t h y l  agree w i t h the l a b e l l i n g  s h i f t s must be  non-concerted  pattern.  (45a o r b)  H  <  <r  (38)  Figure XI:  Boat type f o l d i n g  of X-bisabolene  A much more e l e g a n t and e n e r g e t i c a l l y more f a v o u r a b l e m e t h o d of  folding  to  fold  ring  the side  chain i s to u t i l i s e  a chair-type f o l d i n g but  the side c h a i n i n f r o n t o f the plane of the cyclohexane  as i n F i g u r e X I I r a t h e r t h a n b e h i n d  i t as i n F i g u r e X.  -  (45a  Figure XII:  27  o r b)  Alternative  chair  H a v i n g shown how t h e s i d e aspect of the biosynthesis isomer o f "o'-bisabolene, tunately in direct  -  type f o l d i n g  ofX-bisabolene  c h a i n may be f o l d e d ,  of trichothecin  the next  to discuss  i s which  ( 4 5 a ) o r ( 4 5 b ) , may be i n v o l v e d .  Unfor-  t h e r e s u l t s o b t a i n e d by two d i f f e r e n t r e s e a r c h g r o u p s a r e contradiction.  Starting  from  h a v e shown t h a t  14 (2- C)-mevalonic 1 H  the l a b e l l i n g p a t t e r n  follows: H  acid  lactone,  J o n e s and Lowe  i n trichothecin  i s as  4  28  S t a r t i n g with. Y - b i s a b o l e n e envisaged f o r the b i o s y n t h e s i s  two  alternate  of t r i c h o t h e c i n  schemes c a n  be  CFigures X I I I  and  XIV) .  (45a)  H  0''>  <r~ <—  (38)  Figure XIII:  Labelling pattern of "tf-bisabolene  in trichothecin  from isomer  (45a)  (38)  F i g u r e XIV:  Labelling pattern of Y - b i s a b o l e n e  in trichothecin  from isomer  (45b)  -  29  -  t h u s i t c a n be s e e n t h a t o n l y gives  a r e s u l t w h i c h i s c o n s i s t e n t w i t h t h e w o r k o f J o n e s and Lowe.  However, t h i s joining  i s only  t h e 6-  t h i s bond'then  true i f there  t o t h e 5- membered Figures  c y c l i s a t i o n step. is  i s o m e r C45b) o f ) f - b i s a b o l e n e  XIII  Since  i s no r o t a t i o n a b o u t t h e b o n d  ring.  I f there  i s rotation  a n d X I V become e q u i v a l e n t  i t i s very  unlikely  a f r e e c a r b o n i u m i o n , b u t h a s some g r o u p  a f t e r the  that the intermediate Z attached  at that  p o i n t w h i c h must s u b s e q u e n t l y be e l i m i n a t e d i n a n o r m a l t r a n s a n t i - p a r a l l e l manner, t h e n t h e s t e r e o s p e c i f i c i t y Figures  XIII  and XIV s t i l l  holds:-  about  depicted i n  -  30  -  More r e c e n t w o r k done b y H a n s o n and h i s c o l l a b o r a t o r s , 3 14 d o u b l y l a b e l l e d ( 2 - H,2C) f a r n e s y l p y r o p h o s p h a t e that  the o t h e r isomer  biosynthesis  (18) i n d i c a t e d  (45a) o f 1 ) - b i s a b o l e n e i s i n v o l v e d  of trichothecin  (38).  using  i n the  ( P r e v i o u s w o r k f r o m t h e same  53 group  had already  implicated  farnesyl  pyrophosphate  (18) i n  •7 the • b i o s y n t h e s i s  of t r i c h o t h e c i n ) .  f a r n e s y l pyrophosphate the  following  (18)  labelling  Starting  from  14  (2-°H, 2-  C)  ( 1 8 ) , t h e two i s o m e r s o f ^ - b i s a b o l e n e h a v e patterns:-  (45a)  (45b)  Figure  XV t r a c e s  31  -  the f a t e of the l a b e l s i n each of these  i s o m e r s as t h e y a r e c o n v e r t e d t o t r i c h o t h e c i n ( 3 8 ) . Experimentally  i t was  f o u n d t h a t t h e t r i t i u m was  which i s consistent with.isomer the b i o s y n t h e s i s concerning  (45a) b e i n g  of t r i c h o t h e c i n (38).  retained  t h e one i n v o l v e d i n  The same a r g u m e n t  applies  a Z group mechanism w h i c h e f f e c t i v e l y p r e v e n t s r o t a t i o n  about t h e i n t e r - a n n u l a r bond.  The f a c t t h a t  the r e t e n t i o n of  52 tritium  i s a l m o s t 1001  about t h i s  indicates that  there  c a n be no r o t a t i o n  bond.  48 48 As i t h a d b e e n shown t h a t a c e t a t e , mevalonate, and f a r n e s y l 53 pyrophosphate are i n v o l v e d i n the b i o s y n t h e s i s of t r i c h o t h e c i n , t h e n e x t l o g i c a l s t e p was t o d e t e r m i n e w h i c h m o n o c y c l i c s p e c i e s (if  any) a r e i n v o l v e d .  Preliminary  investigations i n this  54 laboratory  h a v e shown t h a t  i n the b i o s y n t h e s i s c<-bisabolol  (46) may  to give "^-bisabolene of  «K-bisabolol (46) i s n o t a  of t r i c h o t h e c i n (38).  I t was  i t may  be a t r u e  ^-bisabolene.  OH  (46)  thought  have been c a p a b l e o f d e h y d r a t i o n (45) o r t h a t  (45)  precursor that  i n vivo  precursor  -  Figure  XV:  32  -  P o s i t i o n of l a b e l i n t r i c h o t h e c i n and c o - w o r k e r s  according  t o Hanson  -  The w o r k d e s c r i b e d synthesis  33  -  i n t h i s p a r t of the t h e s i s i n v o l v e s a  of^-bisabolene  (45) and t h e f e e d i n g  of t h i s  ( i n r a d i o - a c t i v e form) t o c u l t u r e s o f T r i c h o t h e e i u m significance published  5 5  discussed.  of the r e s t i l t s  ' ^ ' ^ ' ^ during 5  5  Also  5  obtained  the course  the p o s s i b l e mechanisms o f t h e i r results  roseuni.  relevance  of feeding  t o work  syntheses  (47) and f a r n e s o l e p o x i d e ( 4 8 ) , conversion  them t o T r i c h o t h e c i u m  t o t r i c h o t h e c i n , and roseum.  OH  (47)  The  o f t h i s work i s then  i n t h i s p a r t of the t h e s i s are d e s c r i b e d  of r a d i o - a c t i v e monocyclofarnesol  the  and t h e i r  compound  (48)  -  34  DISCUSSION P r e v i o u s w o r k on shown t h a t a c e t a t e , are p r e c u r s o r s to  t h e b i o s y n t h e s i s o f t r i c h o t h e c i n (38)  48  mevalonate,  48  and  of t r i c h o t h e c i n (38).  determine which monocyclic  t h a t o c - b i s a b o l o l (46)  i s not  assuming the o < - b i s a b o l o l  t o be  ( 4 5 ) , w h i c h has  a precursor  test V-bisabolene Y-Bisabolene oxychloride,  (45)  As  the  reason  prepared  obvious  by  the  i n p y r i d i n e , on o < - b i s a b o l o l  s t e p was  ketone  has  been p r e p a r e d  s y n t h e s i s e d by  w i t h ketone  a c t i o n of phosphorus  (46).  >  Ruzicka  a number o f t i m e s 62  and  Liguori  condensing the G r i g n a r d  (50).  (50) was  to  (45)  °<-Bisabolol (46)  i t by  '^ ' ^  5 1  (46)  prepared  to  activity.  3  first  the  i n vivo 3  POCl /Pyridine  was  for  long been c o n s i d e r e d ^ * * ' the next  Bromide  prepared  by  (49) was  before.  i n 1932.  o z o n o l y s i s and  from d i o l  dehydration  It  They  complex of bromide  prepared  54  i n v o l v e d h a v e shown  of dehydration  for precursor  (45) was  be  h a v e b e e n a p r e c u r s o r was  i n this process,  53  Preliminary investigations  a precursor.  f a c t t h a t i t m i g h t have been c a p a b l e ^-bisabolene  f a r n e s y l pyrophosphate  compounds may  (46) may  has  (49)  (51), of  ^-  and  35 terpineol (52).  (51)  (49)  0'  MgBr  (50)  (46)  A synthesis of p-bisabolene and  Guzman  i n 1966.  between ketone  (53) was r e p o r t e d b y M a n j a r r e z  The k e y s t e p i n t h e i r scheme was t h e r e a c t i o n  (54) a n d m e t h y l  triphenyIphosphonium  bromide.  Ketone  (54) was p r e p a r e d by c o n d e n s a t i o n o f t h e G r i g n a r d c o m p l e x o f b r o m i d e  - 36 (49) w i t h , t h e a c i d c h l o r i d e  of a c i d  (55) •  Bromide  (49) ( t h e same  62 one  as u s e d b y R u z i c k a and L i g u o r i  of J u l i a  reacted  Treatment  bromide  (49).  with  Acid  methyl ketone  m e t h y l magnesium b r o m i d e  of c a r b i n o l (55) was  o b t a i n e d by D i e l s - A l d e r acrylate  p r e p a r e d a f t e r the method  and c o - w o r k e r s * ^ f r o m c y c l o p r o p y l  w h i c h was (57).  ) was  (57) w i t h  to give  48% h y d r o g e n  p r e p a r e d by h y d r o l y s i s  (56), carbinol  bromide  gave  of ester  r e a c t i o n b e t w e e n i s o p r e n e (1) and  (58),  methyl  (59).  (59)  (1)  (58)  (55)  - 37 -  0  CH +  Ph PCH Br 3  3  X  (54)  (53)  T h e s e s y n t h e s e s have b e e n c r i t i c i s e d by G u t s c h e workers^  5  who  o f f e r an a l t e r n a t i v e  scheme,  same k e y r e a c t i o n as R u z i c k a and L i g u o r i . is  t h a t i t i s t e d i o u s to prepare ketone 62  R u z i c k a and L i g u o r i |S-terpineol tried  because  and h i s c o -  though u t i l i s i n g  67 " Their f i r s t  methyl v i n y l ketone  o f the d i f f i c u l t y  i n s e p a r a t i n g pure They  (50) by a D i e l s - A l d e r r e a c t i o n  and i s o p r e n e b u t h a d d i f f i c u l t y  the i s o m e r i c m i x t u r e o b t a i n e d , w h i c h  criticism  (50) by t h e method o f  from the c o m m e r c i a l l y a v a i l a b l e m i x t u r e .  to prepare ketone  the  then  between  i n separating  c o n t a i n e d 25% o f u n w a n t e d  isomer (60). They e v e n t u a l l y of 4-keto-cyclohexane  obtained ketone carboxylic  (50) i n l o w y i e l d b y  acid  (61) w i t h m e t h y l  treatment  lithium,  f o l l o w e d by d e h y d r a t i o n . Secondly they c l a i m t h a t the bromide  (49) p r e p a r e d by R u z i c k a  62 and L i g u o r i isomer  (6 2 ) .  contained significant  amounts  of the i s o p r o p e n y l  -  -  38  0  (60)  0  0  (61)  OH  (50)  C62)  Gutsche of-bisabolol  and h i s c o - w o r k e r s  (.46) by c o n d e n s i n g t h e G r i g n a r d  ( 4 9 ) , p r e p a r e d by ketone  tlxen p r e p a r e d a p u r e s a m p l e o f  t h e meth_od o f J u l i a  ( 5 0 ) , p r e p a r e d by  Another synthesis  t h e i r own  of ketone  and c o - w o r k e r s , ^ *  It  i s shown i n F i g u r e  considered  with  (54) has b e e n r e p o r t e d , ^  i s much l e n g t h i e r t h a n t h e o t h e r s i t was  a synthesis  4  bromide pure  method.  it  For  complex o f pure  considered  but  as  unsuitable.  XVI. of r a d i o - a c t i v e c<~bisabolol  t h a t t h e b e s t m e t h o d was  to introduce  (46) i t was the r a d i o - l a b e l i n  (O  0  Ibl  C0 Et 2  (a) Na d u s t ; H c l  (b) KOH/MeOH/H 0; H ; A / C u  Cc) MeMgl  (d) p - T S A / b e n z e n e / A (£) N a H / C O ( O E t ) / D M F / A  CO  Acetone/HCl  (g) B u V / B i ^ O H / Figure  XVI:  2  ^  2  ^  Alternative  s y n t h e s i s o f ketone  (54)  - 40 the  last  step  of the  -  r e a c t i o n s e q u e n c e by  a l l o w i n g ketone  r e a c t w i t h r a d i o - a c t i v e m e t h y l magnesium i o d i d e . was  thus a convenient  -synthesis  of ketone  objective  (46)  method f i n a l l y  unsuccessful  first  to  (54).  (54)  The  The  (54)  a d o p t e d , a f t e r an  a l t e r n a t i v e , was  investigation  a modification  5 4  of the  of  an  reaction  6 3 scheme o f M a n j a r r e z and  Guzman.  (1) w i t h m e t h y l a c r y l a t e esters the  (58)  ratio  desired  and  (58)  a gummy m i x t u r e repeatedly  30%  p o i n t was  results  c o u l d be and  of acids  Hennis  a mixture  of  has  that  shown  reaction i s approximately  unwanted e s t e r  (55)  (63)].  and  ( 6 4 ) , m.p.  from p e t r o l e u m e t h e r  constant obtained  omitting  w o r k by  isoprene  The  70%  mixture  i n aqueous s o d i u m h y d r o x i d e s o l u t i o n t o  crystallised  melting  acrylate  in this  and  hydrolysed  gave, i n good y i e l d ,  [Previous  of products  ester  e s t e r s was  (63).  (59)  Thus c o n d e n s a t i o n o f  a t 99-100°C. using  acrylic  the h y d r o l y s i s  of give  50-100°C, w h i c h  was  (60-80°C) u n t i l  the  Essentially similar a c i d i n s t e a d of  step.  methyl  - 41 -  MeO  (59)  (1)  (58) ~  Confirmation lactonising  p r o c e d u r e gave a w h i t e , infra-red solution  the  8.65 T ,  ^  compound, m.p.  ( i r ) a b s o r p t i o n a t 1760 cm * i n c a r b o n and 1740 cm  i n chloroform  solution.  a^-lactone  nuclear magnetic resonance m e t h y l group a t t a c h e d  (65)  by  This  68-69°C,  with  tetrachloride This  indicated  ring, which i n conjunction  (nmr) s p e c t r u m  to carbon b e a r i n g  t h e s t r u c t u r e as l a c t o n e ( 6 5 ) .  30%  (55) was o b t a i n e d  w i t h 98% f o r m i c a c i d .  crystalline  t h a t . t h e compound p o s s e s s e d with  70%  of the s t r u c t u r e of acid  the p u r i f i e d product  (63)  (singlet at  oxygen)  confirmed  42  -  T h e r e i s some c o n f u s i o n s t r u c t u r e of t h i s structure  (66)  to t h i s  a t 5.68yu (1760  cm  Further proof lactonising  l a c t o n e as  \  l a c t o n e on  i s the and  9  i s t h a t the  b e e n a c i d (55)  but  regarding  the b a s i s of the  the  the  ascribed  i r absorption  i n carbon  i s not  fact  tetrachloride).  lactone  formed  by  that b o t h isomers of lactone  n e i t h e r melts  a t 69°C.  One  a c i d (64)  (66)  other  a c i d l a c t o n i s e d i n t h i s w o r k may  i n s t e a d was  given  literature  a group of F r e n c h workers^**  t h a t s t r u c t u r e (66)  have been p r e p a r e d ^  r e a c t i o n had  i n the  presumably recorded  a c i d (55)  possibility  -  not  have  ( i . e . the D i e l s - A l d e r  a p r e p o n d e r a n c e o f the wrong i s o m e r ) .  This 70  would l e a d to lactone and  (67)  w h i c h has  i t s m e l t i n g p o i n t i s 45°C.  p r e v i o u s l y been  Finally  lactone  synthesised  (65)  has  been  71 synthesised 69°C and  by  i t has  in chloroform  an  a l t e r n a t i v e route  an i r a b s o r p t i o n  solution).  and  o f 1740  These r e s u l t s  i t s melting point i s cm""'" ( p r e s u m a b l y  are  recorded  summarised i n  Figure  XVII. • Bromide r e p o r t e d by  (49)  was  prepared  M a n j a r r e z and  methyl ketone  (56)  carbinol  w h i c h was  o f 48%  (57)  hydrogen  Previous bromide (55)  Guzman.  same way  as  i n the  Thus t r e a t m e n t  of  w i t h m e t h y l magnesium i o d i d e gave converted  i n t o bromide  (49)  synthesis  cyclopropyl  dimethyl by  the  action  bromide.^ 54  work  has  i s allowed  shown t h a t when t h e G r i g n a r d to r e a c t w i t h the  complex, the  only product  i s p r e s u m a b l y f o r m e d by p r i o r  complex  of  a c i d c h l o r i d e of a c i d  i n the n o r m a l manner, i . e . a d d i n g the  Grignard (6 8)  (49)  i n the 6 3  a c i d c h l o r i d e to  obtained formation  i s ester  (68).  of ketone  (54)  the Ester which,  -  43  -  m.p. Figure XVII:  Confirmation  of s t r u c t u r e  of acid  (55)  4S°C  - 44 -  (49) i n the presence alcoholate  of excess Grignard  (69, R = MgBr).  r e a g e n t i s r e d u c e d t o magnesium  The.reducing p r o p e r t i e s of Grignard  72  c o m p l e x e s a r e w e l l known. compete w i t h t h e G r i g n a r d  Alcoholate  ( 6 9 , R = MgBr) c a n now  reagent f o r the a c i d c h l o r i d e , to give  ester (68).  0  (54)  -  I t was the  thought  -  45  that very slow i n v e r s e  a d d i t i o n , i . e . adding  G r i g n a r d reagent to the a c i d c h l o r i d e would  ketone  (54) d i r e c t l y ,  and t h i s p r o v e d t o be  ketone  (54) p r e p a r e d i n t h i s manner a l w a y s  w i t h an i r a b s o r p t i o n a t 1730 remove.  The  impurity proved  cm  1  ,  the case.  desired  However,  c o n t a i n e d an  w h i c h was  t o be e s t e r  g i v e the  impurity,  very d i f f i c u l t  (70) p r e s u m a b l y  formed  by a i r o x i d a t i o n o f t h e G r i g n a r d c o m p l e x f o l l o w e d b y r e a c t i o n the  r e s u l t i n g magnesium a l c o h o l a t e w i t h t h e a c i d  to  chloride.  of  (70)  Thus t h e b e s t m e t h o d f o r p r e p a r a t i o n a normal Grignard with  reaction to give ester  either lithium  alcohol  (69,  R = H)  aluminium hydride  (54)  of ketone (68)  was by  w h i c h on t r e a t m e n t  or methyl l i t h i u m  w h i c h c o u l d t h e n be o x i d i s e d u s i n g  gave Jones  73  Reagent.  T h i s m e t h o d was u s e d i n t h i s  w h i c h was  then converted,  ©C-bisabolol  (46)  synthesis  of ketone  (54),  i n almost quan'titive y i e l d , to  b y t h e a c t i o n o f m e t h y l magnesium i o d i d e .  A similar synthesis  of c x - b i s a b o l o l (46)  has r e c e n t l y been  74  p u b l i s h e d b y some R u s s i a n Grignard converted  workers,  complex o f bromide t o o ( - b i s a b o i o l (46)  (49)  using n i t r i l e  to give ketone  (71)  (54)  and t h e  w h i c h was  w i t h m e t h y l magnesium i o d i d e .  then  -  47  -  0  (46)  - 48 -  0  .  (71) (54)  I n t h e same p a p e r i s d e s c r i b e d an a l t e r n a t i v e bisabolol  using  t h e same r e a g e n t s  order.  Thus n i t r i l e  iodide,  gave k e t o n e  the  action  original  but reacting  ( 7 1 ) , on t r e a t m e n t  complex o f bromide  synthesis of Ruzicka  them i n a d i f f e r e n t  w i t h m e t h y l magnesium  ( 5 0 ) which, was c o n v e r t e d  of the Grignard  s y n t h e s i s o f <X-  i n t o c < - b i s a b o l o l by ( 4 9 ) , as i n t h e  and L i g u o r i .  (46)  - 49 Dehydration  of 0<-bisabolol  i n . p y r i d i n e gave a m i x t u r e bisabolenes  C46)  liquid  (53).  chromatography  180°C) gave p u r e X - b i s a b o l e n e c h a r a c t e r i s e d by  (45)  (54)  (^50%  (45)  and  other  isomeric  Separation of t h i s ( g l c ) (30%  achieved  using r a d i o - a c t i v e methyl  mixture  Carbowax,  of the m i x t u r e )  a n a l y s i s o f i t s i r and nmr  o f r a d i o - l a b e l l e d ^ - b i s a b o l e n e was from ketone  w i t h phosphorus o x y c h l o r i d e  of X-bisabolene  s u c h as ^ - b i s a b o l e n e  by p r e p a r a t i v e gas  was  -  which  spectra.  i n an  Preparation  identical  i o d i d e i n the  manner  initial  Grignard reaction.  (46)  (45)  (53)  + other  A satisfactory achieved, (38)  i t s precursor  c o u l d now  be  of r a d i o - l a b e l l e d purifying isomers  s y n t h e s i s of ^ - b i s a b o l e n e activity  isomer(s)  (45) h a v i n g  been  i n the b i o s y n t h e s i s of  trichothecin  investigated.  To  solution  $-bisabolene  (due  this  end  an aqueous  to the d i f f i c u l t i e s  in  s m a l l amounts o f r a d i o - a c t i v e m a t e r i a l t h e m i x t u r e  was  used),  s o l u b i l i s e d w i t h Tween 20,  was  added t o  of one  - 50 -  week o l d c u l t u r e s o f T r 1 c h o t h i e c i u m allowed  t o grow f o r a f u r t h e r t h r e e  d e c a n t e d and t h e m y c e l i a broth  so  washed w i t h  of the solvent  obtained  The b r o t h was  a little  water.  then  The c o m b i n e d  c a r b o n t e t r a c h l o r i d e , and  gave a c r u d e gum w h i c h was p u r i f i e d b y  l a y e r c h r o m a t o g r a p h y on s i l i c a  to c o n s t a n t of  weeks.  and w a s h i n g s w e r e e x t r a c t e d w i t h  evaporation thin  r o s e u m , ^ and t h e c u l t u r e s  was t h e n r e c r y s t a l l i s e d  gel.  The t r i c h o t h e c i n ( 3 8 )  from p e t r o l e u m e t h e r  r a d i o - a c t i v i t y , which represented  (60-80°C)  a specific  incorporation  0.005%. Hydrolysis  o f t r i c h o t h e c i n (38) t o t r i c h o t h e c o l o n e  m e t h a n o l i c p o t a s s i u m h y d r o x i d e s o l u t i o n , f o l l o w e d by of the t r i c h o t h e c o l o n e ~40%  to constant  o f t h e r a d i o - a c t i v i t y had been l o s t ,  o f t h e 'o'-bisabolene h a d o c c u r r e d results  i n d i c a t e that  trichothecin. have r e p o r t e d The  negative  showed  i n d i c a t i n g that  p r i o r to incorporation.  fl'-bisabolene  5 5  ' ^' 5  5 7  ' ^ 5  (45) i s n o t a p r e c u r s o r  w h i c h agree w i t h  incorporation of^-bisabolene  that degradation These of  this  conclusion.  (45) p r o m p t e d  o f an a l t e r n a t i v e b i o s y n t h e t i c r o u t e  from f a r n e s o l pyrophosphate  that cation  recrystallisation  D u r i n g t h e c o u r s e o f t h i s w o r k two g r o u p s o f w o r k e r s results  consideration (38)  radio-activity  (39) w i t h  to t r i c h o t h e c i n  ( 1 8 ) . I t has been s u g g e s t e d  '  *  ( 7 2 ) m i g h t be i n v o l v e d  i n the biosynthesis of several 75.76 types o f sesquiterpenes s u c h as ot-chamigrene (73), p-chamigrene ( 7 4 ) 75 76 t h u j o p s e n e ( 7 5 ) and c u p a r e n e ( 7 6 ) . A l t h o u g h c a t i o n ( 7 2 ) may be  ? r  formally  d e r i v e d by c y c l i s a t i o n  of ^-bisabolene  (45) i t has been  7 (\ suggested C47).  that  i t may a r i s e by c y c l i s a t i o n  of monocyclofarnesol  / J  (73)  - 52 Thus i t i s p o s s i b l e cyclofarnesol Cyclisation cation  (47)  c o u l d be  converted to the trich.oth.ecin s k e l e t o n .  of monocylofarnesol  (72) w h i c h ,  after  cuparane type c a t i o n &-bisabolene  t o c o n s t r u c t a m e c h a n i s j a w L e r e b y mono-  ring  (47) c o u l d p r o v i d e s p i r o - b i c y c l i c  c o n t r a c t i o n , would p r o v i d e  (77) i d e n t i c a l t o t h a t o b t a i n e d by  (45) .  (45)  the cyclising  -  To farnesol  53  -  test this proposal a radio-labelled (47} was  k e t o n e , |3-ionone sterically  prepared (78) was  as f o l l o w s . reduced,  approximately  10%  (79).  I t was  found  (79)  with trimethyl  cis-  trans-methyl monocyclofarnesate  with  60:40.  l i t h i u m aluminium  Reduction hydride  (80) was  of methyl  the  reaction  formed.  i n a modified  phosphonoacetate  at  bond t o g i v e  t h a t d u r i n g the  reaction  approximately  double  of tetrahydro-y5-ionone  R e a c t i o n o f dihydro-jS - ionone  naturally occurring C  u s i n g Raney n i c k e l ,  less hindered di-substituted  dihydro-^-ionone  and  The  sample o f monocyclo-  Wittig  (81) gave a m i x t u r e (82)  in a ratio  of  of  monocyclofarnesate  t h e n gave m o n o c y c l o f a r n e s o l  (82) (47).  - 54 -  (MeO) - P - C H -CO" Me 2  ^  2  (MeO) -P-CH-C0 Me 2  (82)  (47)  A sample o f r a d i o - a c t i v e l y prepared trimethyl and  2  i n an e x a c t l y  l a b e l l e d m o n o c y c l o f a r n e s o l was  s i m i l a r manner u s i n g  phosphonoacetate  radio-labelled  p r e p a r e d by h e a t i n g t r i m e t h y l  phosphite  1 - ^ C - m e t h y l bromoacetate ( 8 3 ) . A d m i n i s t r a t i o n o f a sample o f r a d i o - l a b e l l e d  (4 7) t o T r i c h o t h e c i u m roj^cum, trichothecin  monocyclofarnesol  f o l l o w e d by i s o l a t i o n o f t h e  ( 3 8 ) i n t h e manner d e s c r i b e d above gave a s p e c i f i c  -  -  55  0 (MeO) P  +  3  Br-CH -C0 Me 2  (MeO) - P - C H C 0 M e  2  2  2  2  (81)  (83)  (79) *C0 Me 2  OH LAH  (47)  (82)  i n c o r p o r a t i o n o f 0.003%.  Hydrolysis  l o s s o f 70% o f t h e r a d i o a c t i v i t y degradation  had taken  I n d i r e c t support and  monccyclofarnesol  (39) w i t h  indicated that s u b s t a n t i a l  place prior f o r these  to trichothecolone  to incorporation.  results with ^-bisabolene  (47) has been p r o v i d e d  during  (45)  the course 55-58  o f t h i s w o r k b y two g r o u p s o f w o r k e r s who h a v e r e p o r t e d  results  which are c o n s i s t e n t w i t h our conclusions. The  first  55  N  o f those  (84), a cuparane type  concerns the b i o s y n t h e s i s of h e l i c o b a s i d i n  of sesquiterpene. OH  H0 C 2  CH 0H 2  4R-(4- H, 2- C) mevalonic acid 3  1 4  56  -  When 4 R - ( 4 - ^ H , 2 - C ) m e v a l o n i c a c i d l a c t o n e was 1 4  o r g a n i s m w h i c h p r o d u c e d h e l i c o b a s i d i n (84) i t was  f e d to the  found that 2 of  t h e p r o - R - h y d r o g e n atoms f r o m t h e m e v a l o n i c a c i d l a c t o n e  (tritium  in this  these  case) were r e t a i n e d i n t h e h e l i c o b a s i d i n .  Since  are  t h e h y d r o g e n atoms w h i c h a r e known t o be l o c a t e d on t h e d o u b l e 24 bonds o f f a r n e s y l p y r o p h o s p h a t e intermediacy  of ^-bisabolene  ( 8 4 ) , and h e n c e p r o b a b l y least  the  The o t h e r  5  sesquiterpenes,  As t h e t r i c h o t h e c a n e  of ^-bisabolene  results ^  5  the  i n the b i o s y n t h e s i s of h e l i c o b a s i d i n  cuparane s k e l e t o n t h i s  intermediacy  seems t o p r e c l u d e  a l l cuparane type  i n micro-organisms.  rearranged  this  result  at  skeleton i s a  a l s o seems t o  preclude  i n the b i o s y n t h e s i s of t r i c h o t h e c i n .  ^ a r e f r o m H a n s o n ' s l a b o r a t o r y and  c o n c e r n h e l i c o b a s i d i n ( 8 4 ) , t r i c h o t h e c i n ( 3 8 ) and t r i c h o d e r m i n ( 4 3 ) . T h i s g r o u p h a s s t u d i e d t h e f a t e o f m e v a l o n o i d h y d r o g e n atoms and f r o m t h e s e s t u d i e s h a s o b t a i n e d i n f o r m a t i o n on t h e b i o s y n t h e s i s 3 14 of these  three  compounds.  a c i d was  f e d i t was  Thus when ( 2 - H , 2  found ^ 5  that 5 t r i t i u m  2-  C) m e v a l o n i c  atoms h a d b e e n i n c o r p o r -  a t e d i n t o t r i c h o d e r m i n ( 4 3 ) . H y d r o l y s i s o f t h e a c e t a t e g r o u p and o x i d a t i o n o f t h e s e c o n d a r y a l c o h o l so f o r m e d r e s u l t e d i n l o s s o f 1 - 3 14 t r i t i u m atom. When 2 R - ( 2 - H, 2C) m e v a l o n i c a c i d was f e d i t was found t h a t t h e r e were 2 t r i t i u m after oxidation. the  acetoxy  This  atoms i n c o r p o r a t e d b e f o r e  defines which hydrogen i s l o s t  and  i n introducing  group.  A similar  experiment w i t h  incorporation of 4 t r i t i u m  t r i c h o t h e c i n ( 3 8 ) showed t h e  atoms b e f o r e  o x i d a t i o n and 2  tritium  atoms a f t e r o x i d a t i o n when ( 2 - H , 2 - C ) m e v a l o n i c a c i d , was f e d 3  as  a precursor.  that  The c o n c l u s i o n s  1 4  drawn f r o m t h e s e  t h e h y d r o x y l a t i o n o f t h e 5-membered r i n g  r e t e n t i o n o f c o n f i g u r a t i o n a t C^, trichothecin  (38) a t r i t i u m  experiments are  occurs  with  overall  and t h a t i n t h e b i o s y n t h e s i s o f  atom m i g r a t e s  from C  p  to C  r/  (where i t  -  57  -  (43)  4 T retained  2T  retained  5 T  2T  retained  retained  -  58  -  4T r e t a i n e d  R =  is  isocrotonyl  e a s i l y exchanged, hence  oxidation).  (38) the loss  o f 2 t r i t i u m atoms  4T  retained  retained  after  F u r t h e r e v i d e n c e f o r t h i s m i g r a t i o n was p r o v i d e d 3  by f e e d i n g  2T  ( 5 - H^, 2 -  14 C) m e v a l o n i c a c i d when o n l y 4 o f t h e  e x p e c t e d 5 tritium„atoms a r e r e t a i n e d . The involved  authors suggest that i n the biosynth.esis  rearranged to t r i c h o t h e c i n  the epoxide c r o t o c i n of trichothecin  (38).  ( 8 5 ) may be  and t h a t  i t may be  - 59 -  57 I n the. s e c o n d p a p e r  of this  s e r i e s Hanson and h i s g r o u p  r e p e a t t h e work o f t h e J a p a n e s e w o r k e r s getting  t h e same r e s u l t .  geranyl  pyrophosphate  5 5  on h e l i c o b a s i d i n ( 8 4 )  I n a d d i t i o n , by f e e d i n g  ( 1 7 ) t h e y show t h a t  3 14 ( 2 - H, 2~ C)  one o f t h e t r i t i u m  3 14 atoms r e t a i n e d when 4 R - ( 4 - H, 2- C) m e v a l o n i c a c i d i s f e d must be f r o m t h e c e n t r a l m e v a l o n o i d u n i t , t h u s c l e a r l y s h o w i n g ^-bisabolene  ( 4 5 ) c a n n o t be a p r e c u r s o r  that  as t h i s h y d r o g e n i s l o s t 52  i n forming "ft-bisabolene. shown t h a t  2 tritium  In a previous paper  atoms a r e r e t a i n e d  this  group had  i n t r i c h o t h e c i n when  14  3  4 R - ( 4 - H, 2-  C) m e v a l o n a t e was f e d t o t h e o r g a n i s m  producing  trichothecin.  One o f t h e s e t r i t i u m a t o m s , l o c a t e d  a t C ^ Q , was  52 shown  t o come f r o m t h e t e r m i n a l  pyrophosphate C^,  mevaloid unit  ( 1 8 ) , and t h e o t h e r t r i t i u m  b u t i t s o r i g i n was n o t d e f i n e d .  geranyl  pyrophosphate  located  at C  0  pyrophosphate a precursor  of farnesyl  atom was l o c a t e d a t  By f e e d i n g ( 2 , 57  ( 1 7 ) t h e y now showed  that  H, 2-  the hydrogen  comes f r o m t h e c e n t r a l m e v a l o n o i d u n i t (18).  This  also  of t r i c h o t h e c i n .  suggest a p o s s i b l e  C)  of farnesyl  c l e a r l y p r e c l u d e s Y - b i s a b o l e n e as  Hanson and h i s c o l l a b o r a t o r s 57 c o n c e r t e d mechanism' f o r the biosynthesis  -  60  -  - 61 -  o f t r i c h o t h e c i n , a mechanism i n w h i c h a hydrogen  shift  occurs  i n an enzyme d i s p l a c e m e n t s t e p . 58 In the t h i r d  paper t h i s  group  e x p e r i m e n t s on t h e b i o s y n t h e s i s confirmation of cuparane  describes  some f u r t h e r  o f h e l i c o b a s i d i n (84) w h i c h add  t o t h e i r s u g g e s t e d mechanism f o r t h e b i o s y n t h e s i s type  sesquiterpenes.  I n an a l t e r n a t i v e m e c h a n i s m f o r t h e b i o s y n t h e s i s o f trichothecin appears  ( 3 8 ) i t was c o n s i d e r e d  at  failure  the oxygen f u n c t i o n which  °f t r i c h o t h e c i n (38) may b e i n t r o d u c e d  from a p r e c u r s o r the  that  s u c h as f a r n e s o l e p o x i d e  to incorporate  very  early  (48), which could  explain  t h e p r e v i o u s l y t e s t e d compounds. OH  as f o r monocyclof arnesol  (48)  H =  .0  OR (38)  62 -  Although, f a r n e s o l one o f i t s e n a n t i o m e r i c by c e r t a i n racemic  fungi,  farnesol  epoxide  (48) has n o t b e e n f o u n d i n n a t u r e 79  f o r m s has b e e n f o u n d  and t h i s epoxide  t o be  metabolised  f a c t has b e e n u s e d i n a r e s o l u t i o n  (48).  F a r n e s o l epoxide  has a l s o  of  been  p o s t u l a t e d as a p r e c u r s o r i n t h e b i o s y n t h e s i s o f t h e s e s q u i t e r p e n o i d 80 ' , 81 compounds i r e s i n (86) and f a r n e s i f e r o l - A ( 8 7 ) .  (86)  Geranyl  (87)  acetone.  (88) was  considered  mediate i n a s y n t h e s i s of r a d i o - l a b e l l e d  t o be a s u i t a b l e farnesol  epoxide  inter(48).  82 Geranyl  acetone  (88) h a s b e e n p r e p a r e d , b e f o r e  g e r a n y l b r o m i d e (89) w i t h t h e a n i o n f o l l o w e d by h y d r o l y s i s  of e t h y l  u  by  condensing  acetoacetate  (90) ,  and d e c a r b o x y l a t i o n o f t h e i n t e r m e d i a t e  ,g-keto-ester (91).  (89)  (90)  ,  (91)  - 63 l)NaOH/H 0 2  2)H  0  ^  (88) G e r a n y l bromide phosphine  and  (89) was  p r e p a r e d by  the a c t i o n of  c a r b o n t e t r a b r o m i d e on g e r a n i o l  + CBr  + PPh,.  4  (92).  The  triphenyl reaction  —>  (89)  (92) 83 is  thought Ph P:' + + Ph P-Br  t o p r o c e e d as f o l l o w s : Ph P-Br 3 Br-CBr. + ROH Ph^-O-R CBr.  Ph,?0-R ~  +  CBr  3  3  3  -,Ph P 3  From g e r a n y l a c e t o n e p o s s i b l e , namely p r i o r by s u b s e q u e n t  f o r m a t i o n of the epoxide f u n c t i o n  For reasons o u t l i n e d below  methods was  f o r the s y n t h e s i s  considered that  (a) t h i s  are  followed  a l c o h o l m o i e t y , or the  r e v e r s e sequence.  i t was  CHBr.  routes to f a r n e s o l epoxide  e l a b o r a t i o n of the a l l y l i c  chosen  Br  RBr  0  (88) two  +  3  the f i r s t  of these  of f a r n e s o l epoxide.  route e n t a i l e d  Thus  i n s e r t i o n of the  - 64 -  radio-label it two  at a l a t e r  stage than the a l t e r n a t e route,  involved epoxidation  o f one d o u b l e b o n d s e l e c t i v e l y  d o u b l e bonds r a t h e r t h a n from Model  and (b) from  only  three.  s t u d i e s were p e r f o r m e d r e a c t i n g v a r i o u s d e r i v a t i v e s  of 2-bromo-ethanol derivatives  i n W i t t i g r e a c t i o n s w i t h ketone  (93) t o g i v e  o f g e r a n i o l (92) b u t t h e r e s u l t s were d i s a p p o i n t i n g  w i t h no e v i d e n c e f o r t h e f o r m a t i o n  of geraniol d e r i v a t i v e s being  obtained.  BrCH CH OR 2  •>  ''\  2  Ph^CH^CHAOR - Br  In another attempt t o produce  geraniol  (92) from k e t o n e (93) 84  a m o d i f i c a t i o n o f a r e a c t i o n used by Corey synthesis c*-santalol ethylidine Wittig mediate  of  °<-santalol  ( 9 4 ) was t r i e d .  In t h e i r  ( 9 4 ) C o r e y a n d Yamamoto r e a c t e d t r i p h e n y l phosphorane  type intermediate  (96).  a n d Yamamoto  At this  synthesis of  aldehyde  a t -78°C t o g i v e  (95) w i t h  the normal  low t e m p e r a t u r e  ( 9 6 ) i s s t a b l e a n d a d d i t i o n o f one e q u i v a l e n t  gave 6 - o x i d e p h o s p h o n i u m  ylide  in a  ( 9 7 ) w h i c h was a l l o w e d  inter-  o f base to react  with  -  paraformaldehyde C94).  a t Q°C.  65  -  A q u e o u s w o r k up t h e n gave  The m e c h a n i s m and s t e r e o c h e m i s t r y o f t h i s  fc<-santalol  interesting  H  0  (94)  reaction  have been r e v i e w e d .  I t was aldehyde of  thought that  by u s i n g m e t h y l k e t o n e  ( 9 5 ) , and u s i n g m e t h y l e n e  ethylidine  produced; a compound  triphenyl  triphenyl  phosphorane,  When t h e r e a c t i o n  geraniol  (9 3) i n s t e a d  phosphorane (92) m i g h t  was c a r r i e d o u t u s i n g  of  instead be  those reagents  - 66 was produced i n about 25% y i e l d  ( p u r i f i e d by g l c ) which, e x h i b i t e d  s p e c t r a l c h a r a c t e r i s t i c s very s i m i l a r to g e r a n i o l c l o s e r e x a m i n a t i o n o f the nmr s p e c t r u m ^ comparison w i t h an a u t h e n t i c the c i s - d o u b l e  (Figure X V I I I ) ,  However and  sample showed t h a t the compound was  bond i s o m e r , n e r o l ( 9 8 ) .  (98)  (92).  - 67 geraniol  nerol  Predicted yalue  8 . 34 C.2)., 8 . 40 (1)  Authentic sample  -8 . 3 3 ( 2 ) , 8 .41 (1)  8 . 27 (1) , 8 . 34 U ) , 8 . 40 (1) 8 . 27 C I ) , 8 . 31 QL) , 8 . 39 C I )  Synthetic sample  8.27 C I ) ,8.32 CI) , 8 . 3 8 ( 1 )  Cvalues are i n % u n i t s , f i g u r e s i n p a r e n t h e s e s are no. o f methyl groups) Figure XVIII: As  the y i e l d  purification this  of this  f o r g e r a n i o l and n e r o l r e a c t i o n was r a t h e r l o w , and t h e  of a small radio-active  sample would  be  difficult,  r o u t e was a b a n d o n e d . The  prior  nmr v a l u e s  best route to farnesol  formation of farnesol  C88) v i a m e t h y l  epoxide  C48) t h u s a p p e a r e d  C99) , p r e p a r e d f r o m g e r a n y l  f a r n e s a t e (10 0) i n a manner a n a l o g o u s  acetone  to the  p r e p a r a t i o n o f m o n o c y c l o f a r n e s o l C47) f r o m d i h y d r o - j S - i o n o n e f o l l o w e d by s e l e c t i v e  e p o x i d a t i o n o f the 10,11-double  0  CMeO) -P-CH C0 Me (83) 2  2  2  >  (88)  (100)  t o be  bond.  (79),  - 68 -  LAH  (48) Reaction the  of geranyl  acetone  a c t i o n o f sodium h y d r i d e  gave m e t h y l f a r n e s a t e ester  (100) w i t h  identical  (88) w i t h t h e a n i o n  formed by  on t r i m e t h y l p h o s p h o n o a c e t a t e  ( 1 0 0 ) i n good y i e l d .  l i t h i u m aluminium hdyride  i n a l l respects with  Subsequent  (81) reduction  gave f a r n e s o l ( 9 9 )  an a u t h e n t i c s a m p l e o f f a r n e s o l . 8 7 88  I t h a s a l r e a d y b e e n shown b y v a n T a m e l e n and c o - w o r k e r s t h a t p o l y e n e s s u c h as f a r n e s o l (99) and s q u a l e n e selectively  epoxidised  (24) may be  a t t h e t e r m i n a l d o u b l e b o n d by  w i t h N - b r o m o s u c c i n i m i d e i n aqueous g l y m e ( d i m e t h o x y  treatment ethane),  f o l l o w e d by base c a t a l y s e d r i n g c l o s u r e o f t h e i n t e r m e d i a t e hydrin. fact on  The s e l e c t i v i t y  that i n this  itself  exposing  i n these  reactions i s probably  s o l v e n t system the f a r n e s o l chain only  t h e ends t o t h e  T r e a t m e n t o f f a r n e s o l (99) w i t h succinimide methanolic spectral  '  bromo  due t o t h e  i s coiled  reagent.  one e q u i v a l e n t  o f N-bromo-  i n 70% aqueous g l y m e , f o l l o w e d b y r e a c t i o n w i t h potassium hydroxide  characteristics  epoxide ( 4 8 ) .  up  s o l u t i o n gave a p r o d u c t  i n d i c a t e d t h a t i t was  whose  farnesol-10,11-  -  69  -  NBS aqueous  glyme  (99) KOH/MeOH  (48) Preparation (48) was  o f a r a d i o - l a b e l l e d sample  a c h i e v e d i n an e x a c t l y  of farnesol  epoxide  a n a l o g o u s manner s t a r t i n g  14 1-  C-methyl  bromoacetate  (MeO) P + Br-CH -C0 Me 3  2  (83)  2  (83) and t r i m e t h y l p h o s p h i t e . 0  ^  II  (MeO) P 2  -CH C0 Me 2  2  (81)  C791  with  Administration  of a sample o f r a d i o - l a b e l l e d f a r n e s o l  (48)  to Trichothecium  (38)  i n the u s u a l  Hydrolysis  roseum f o l l o w e d  manner gave a s p e c i f i c  to t r i c h o t h e c o l o n e  radioactivity  by  indicated that  (39)  with  epoxide  i s o l a t i o n of the t r i c h o t h e c i n i n c o r p o r a t i o n of l o s s o f o v e r 501  f a r n e s o l epoxide i s not  0.007%. of  a  the  precursor  of t r i c h o t h e c i n . As epoxide  Y bisabolene _  (48)  (45), monocyclofarnesol  h a v e a l l b e e n shown n o t  i n the b i o s y n t h e s i s direct cyclisation  5  ^  by  H a n s o n and  (18)  to a  Experimental A very  details recent  i s the  in their  o f t h e i r work h a v e v e r y  p u b l i c a t i o n by  M a c h i d a and (101)  compound o b t a i n e d  XVI).  migration  mechanism.  r e c e n t l y been 90 Nozoe  8 published.  describes  i n t o t r i c h o t h e c i n (38).  a f t e r the m i g r a t i o n  m e t h y l g r o u p s i n the p o s t u l a t e d b i o s y n t h e t i c schemes and  the  his collaborators is  i t is postulated  i n c o r p o r a t i o n of t r i c h o d i e n e  Trichodiene  activity  cuparane  c o r r e c t . H o w e v e r i t i s p o s s i b l e t h a t the h y d r i d e  i s more c o m p l e x t h a t as  XIII  farnesol  to e x h i b i t prec u r s o r  of f a r n e s y l pyrophosphate 5  the  and  o f t r i c h o t h e c i n ( 3 8 ) , i t w o u l d seem t h a t  s k e l e t o n , as p r o p o s e d ^ probably  (47)  (see  of  the  Figures  -  71  (101)  -  F i g u r e XX:  Nuclear magnetic resonance spectrum of  Trichothecin  3000 j tit  i l i.tt-,i  i I  i  i  2000 I  1 i I i t  1500 t  t  i  t  ,  I  CM-l  1000  7 8 9 10 WAVELENGTH (MICRONS)  F i g u r e XXI:  I n f r a r e d spectrum o f Trichothecolone  900  I,I,U  800  ,f, i.(, i ,1, „ i , ?, w ,  1,  700  T  ~T  * r • 500  1 >  1 1  1  I  1  1 i  1  I  1  1  1 I  1  1  400 ! •  Figure XXII:  .1  I I I . ! 1  1 .  3 0 0  1  1  1  1  1  1  |  1  1  j  | | | 1 1 1200  Nuclear magnetic resonance spectrum of  1 1  1 I  1 1  •!  1  1 !  1  1  :  Trichothecolone  1  I  100  1  1 1  I  1  1 1  )_  1 j  1 ' i  1 !  ()  t  - 76 -  EXPERIMENTAL All  m e l t i n g p o i n t s were d e t e r m i n e d  I n f r a r e d s p e c t r a CO max)  are u n c o r r e c t e d . Perkin-Elmer  on a K o f l e r b l o c k were r e c o r d e d  I n f r a c o r d m o d e l 137 s p e c t r o p h o t o m e t e r .  m a g n e t i c r e s o n a n c e s p e c t r a (f) w e r e d e t e r m i n e d chloride  A-60  In carbon  (where a p p r o p r i a t e )  i n t e g r a t e d peak areas  are i n d i c a t e d i n parentheses;  br.s  d = doublet,  m o d e l MS  singlet, Mass  t = triplet,  Mr. P. B o r d a , M i c r o a n a l y t i c a l  s =  were p e r f o r m e d by  Laboratory, University  Thin l a y e r chromatographic  singlet,  w i t h an A E I  +  Microanalyses  and  q = quartet,  s p e c t r a ( M ) were d e t e r m i n e d  9 spectrometer.  Columbia.  model  as an i n t e r n a l s t a n d a r d ; t h e  coupling constants  m = multiplet.  on a J e o l c o  S i g n a l p o s i t i o n s are given i n the T i e r s  scale with tetramethyl silane  = broad  tetra-  o r on V a r i a n A s s o c i a t e s s p e c t r o m e t e r s ,  o r m o d e l T-60.  multiplicity,  on a  Nuclear  o r d e u t e r i o c h l o r o f o r m s o l u t i o n and r e c o r d e d  C-60H s p e c t r o m e t e r  and  r e s u l t s were  of  British  obtained  254 using s i l i c a  g e l HF  o f 0.5 mm  measured w i t h a N u c l e a r - G h i c a g o Scintillation calculated was  Radioactivity  M a r k I M o d e l 6860  The r a d i o a c t i v i t y  t a k i n g i n t o account  determined  technique  counter.  thickness.  (see instrument  o f a s a m p l e was  the counting e f f i c i e n c y  manual) u t i l i s i n g  which  The l i q u i d  the b u i l t - i n  scintillation  u s e d w i t h t h e c o u n t e r was made up f r o m L i q u i f l u o r (42 ml) and t o l u e n e  concentrations  Liquid  f o r e a c h s a m p l e by t h e e x t e r n a l s t a n d a r d  b a r i u m - 1 3 3 gamma s o u r c e .  Nuclear)  was  of reagents:  (4 g) and 1 , 4 - b i s  (1 1 ) , g i v i n g toluene  (1 1 ) ,  solution (New  England  the f o l l o w i n g 2,5-diphenyloxazole  [ 2 - ( 5 - p h e n y l o x a z o l y l ) ] benzene  (0.05 g ) .  - 77 I n p r a c t i c e a w e i g h e d s a m p l e was d i s s o l v e d i n b e n z e n e a counting Methyl  vial  and made up t o 15 m l w i t h s c i n t i l l a t i o n  solution.  ( 4 - m e t h y l c y c l o h e x -3-ene) c a r b o x y l a t e ( 5 8 )  Isoprene (11.3  (1 m l ) i n  (1) (9.0 g, 0.13 m o l e ) , m e t h y l a c r y l a t e ( 5 9 )  g , 0.13 m o l e ) and h y d r o q u i n o n e  ( 0 . 5 g) w e r e s e a l e d ,  under  vacuum, i n a g l a s s t u b e and h e a t e d a t 80°C o v e r n i g h t .  The  r e s u l t i n g c o l o u r l e s s o i l was d i s t i l l e d  (4-methyl-  c y c l o h e x - 3-ene) c a r b o x y l a t e isomer  to give methyl  (58) [plus a l i t t l e  o f the 3-methyl  ( 6 3 ) ] ( 1 4 . 7 g, 73.5%) as a c o l o u r l e s s o i l ,  (11 mm)  [lit.  6  85-86° (15 mm)]. X )  7  (liquid  b . p . 78-80°C  f i l m ) 2925,  ITlclX  1735,  1430 , 1170 cm' ; T ( C C 1 ) 4.63 ( s , 1H) , 6.36 1  4  ( s , 3H) ,  7.20-8.20 (m, 7 H ) , 8.33 ( s , 3 H ) . 4 - M e t h y l c y c l o h e x - 3 - e h e c a r b o x y l i c a c i d (5 5) (a) M e t h y l  (4-methylcyclohex-3-ene) carboxylate  ( 5 8 ) ( 1 4 . 7 g,  0.09 m o l e ) was a d d e d t o a s o l u t i o n o f s o d i u m h y d r o x i d e in  water  (60 m l ) . The m i x t u r e  was homogeneous ether  a t 65°C u n t i l i t  («~-^2 h r ) , when i t was c o o l e d a n d e x t r a c t e d w i t h  t o remove u n c h a n g e d s t a r t i n g m a t e r i a l .  was t h e n  acidified  extracted three  a gummy w h i t e petroleum  times  carboxylic  w i t h benzene.  w i t h b r i n e and e v a p o r a t e d  (60-80°C) t o g i v e  (lit.  cm ; T(CDC1 ) - 1  3  6  7  i n vacuo t o g i v e  crystallised  from  4-methylcyclohex-3-ene  a c i d ( 5 5 ) ( 2 . 5 g, 19%) as w h i t e ,  99-100°C  s u l p h u r i c a c i d and  The c o m b i n e d b e n z e n e e x t r a c t s  s o l i d w h i c h was r e p e a t e d l y  ether  The b a s i c s o l u t i o n  (litmus) with concentrated  were w a s h e d t h o r o u g h l y  m.p.  was s t i r r e d  ( 1 1 . 5 g)  98.5-99°C). "O  glistening  (CHClj)  needles,  2 9 0 5 , 2655, 1705  1.13 ( s , 1H) , 4.36 ( s , 1H) , 7.4-8.2 (m, 7H) ,  - 78 -  8.37 ( s , 3H) . (b)  Acrylic  and  acid  hydroquinone  tubes  ( 4 5 . 2 g, 0.63 m o l e ) ,  isoprene  ( 0 . 8 g) w e r e s e a l e d , u n d e r vacuum, i n 4 g l a s s  and h e a t e d  a t 95°C f o r 16 h r .  was r e p e a t e d l y c r y s t a l l i s e d  The r e s u l t i n g  from petroleum  ether  to give 4-methylcyclohex-3-ene c a r b o x y l i c a c i d 301)  identical  4-Methylcyclohex-3-ene c a r b o x y l i c a c i d 0.72 mmole) a n d 98% f o r m i c a c i d The r e a c t i o n m i x t u r e  water.  gummy  (60-80°C)  under  (a) above.  l a c t o n e (65)  ( 5 5 ) (100 mg,  (2 m l ) w e r e h e a t e d  overnight at  was w o r k e d up b y a d d i n g  e t h e r and  The a q u e o u s l a y e r was e x t r a c t e d t w i c e w i t h e t h e r  combined e t h e r e x t r a c t s washed t w i c e w i t h b r i n e , t w i c e saturated and  aqueous sodium b i c a r b o n a t e  d r i e d (Na2SO^).  Evaporation  solution,  of the ether  ether  carboxylic m.p.  acid  (60-80°C) t o g i v e lactone  68-69°C ( l i t .  1230,  7  1 0 7 0 , 960 c m  1  _ 1  (CHC1J II13.X  cm"  1  m a x  plates,  ( C C 1 ) 2950, 1760, 4  2 9 6 5 , . 1 7 4 0 , 1 2 3 0 , 1 0 7 0 , 960  o  4  Methyl  (57)  i o d i d e (186.0 g , 1.31 m o l e ) i n e t h e r  added t o magnesium t u r n i n g s  the  from  ; T ( C C 1 ) 7.50 ( s , 1H) , 8.20 ( s , 8H) , 8.65 ( s , 3H) .  2-cyclopropylpropan-2-ol  so  pressure  4-hydroxy-4-methylcyclohexane  68.0-68.7°C)."O  ;^0  with  a t reduced  ( 6 5 ) ( 5 2 . 0 mg, 52.0%) as w h i t e  m.p.  and t h e  twice w i t h brine  gave s l i g h t l y y e l l o w c r y s t a l s w h i c h w e r e r e c r y s t a l l i s e d petroleum  solid  ( 5 5 ) ( 2 6 . 6 g,  i n a l l respects to that prepared  4-Hydroxy-4-methylcyclohexane c a r b o x y l i c a c i d  80°C.  ( 4 2 . 8 g, 0.63 m o l e )  as t o m a i n t a i n  a vigorous  r e a c t i o n mixture  (350 m l ) was  ( 3 5 . 0 g, 1.46 m o l e ) a t s u c h a r a t e reflux.  was h e a t e d  A f t e r the r e a c t i o n subsided  on a h o t w a t e r b a t h  f o r 0.5 h r .  - 79 On c o o l i n g t o 0°C, c y c l o p r o p y l m e t h y l k e t o n e mole) i n e t h e r mixture cooled  (350 m l ) was a d d e d w i t h s t i r r i n g ,  stirred  The m i x t u r e  They were t h e n 3 times  and t h e r e a c t i o n  a t room t e m p e r a t u r e f o r 2 h r , when i t was  t o 0°C and s a t u r a t e d aqueous  added.  ( 5 6 ) (100.0 g, 1.19  was s t i r r e d  separated  with ether.  again  ammonium a c e t a t e s o l u t i o n  until  two c l e a r l a y e r s r e s u l t e d .  and t h e aqueous  l a y e r was e x t r a c t e d  The c o m b i n e d o r g a n i c  l a y e r s were w a s h e d  b r i n e , d r i e d (MgSO^) and t h e e t h e r e v a p o r a t e d a y e l l o w o i l w h i c h was d i s t i l l e d t o  with  i n vacuo t o give  give.2-cyclopropylpropan-2-ol  (57)  ( 8 6 . 5 g, 73%) as a c o l o u r l e s s o i l , b . p . 124-128°C (760 mm)  (lit.  6  4  b . p . 121-122°C). X )  0  (liquid  f i l m ) 3400, 3 1 0 0 , 2 9 5 0 ,  111 3. JC  1460, 1 1 5 0 , 1020 , 960 , 9 2 0 , 8 4 5 , 825 c m " ; T ( C C 1 ) , 7.66 ( s , 1H) , 1  4  8.86 ( s , 6 H ) , 9.00-9.40 (m, 4 H ) , 9.73 ( d , J = 6 H z , 6 H ) . 5-bromo-2-methylpent-2-ene (49) To 2 - c y c l o p r o p y l p r o p a n - 2 - o l a d d e d , w i t h c o o l i n g and s t i r r i n g , o f 0.3 h r .  After stirring  ( 5 7 ) ( 8 6 . 5 g , 0.865 m o l e ) was 48% HBr (410 ml) o v e r a p e r i o d  f o r 0.5 h r w i t h c o o l i n g and 0.5 h r  a t room t e m p e r a t u r e t h e r e a c t i o n m i x t u r e  was e x t r a c t e d 3  w i t h e t h e r , t h e c o m b i n e d e t h e r e x t r a c t s were w a s h e d w i t h s a t u r a t e d aqueous b r i n e , d r i e d (Na2S0 ) 4  to  sodium b i c a r b o n a t e  g i v e an o i l w h i c h was d i s t i l l e d t o g i v e  (60 mm)  [lit.  6  4  thoroughly  s o l u t i o n , washed  and t h e e t h e r e v a p o r a t e d  2-ene ( 4 9 ) 102.7 g , 72.5%)  times  at reduced  with pressure  5-bromo-2-methylpent-  as a c o l o u r l e s s o i l , b . p . 77-82°C  b . p . 84-85°C (84 mm)]. \)  (liquid  f i l m ) 2960,  in 3.x  2 9 2 5 , 1 6 7 0 , 1 4 4 5 , 1 3 7 5 , 1 2 6 5 , 1 2 0 5 , 1 0 9 5 , 835 c m " ; T ( C C 1 ) 1  4  ( t , J = 7Hz, 1 H ) , 6.77 8.33 ( d , J = 4 H z , 6H) .  4.83  ( t , J = 7Hz, 2 H ) , 7.53 ( t , J = 7Hz, 2 H ) ,  - 80 1~C4 ' - ^ M e t h y l c y c l o h e x - 3 ' - e n y l ) - 1 - (4 ' - m e t h y l c y c l o h e x - 5 - e n y l c a r b o x y ) 1  5-methylhex-4-ene (68) To  the G r i g n a r d complex, prepared  from  5-bromo-2-methylpent-  2-ene ( 4 9 ) ( 3 4 . 2 g, 0.21 m o l e ) and magnesium t u r n i n g s 0.23 m o l e ) i n d r y e t h e r  ( 5 . 5 g,  (100 m l ) , was a d d e d c u p r o u s c h l o r i d e  (200  mg) and t h e a c i d c h l o r i d e o f 4 - m e t h y l c y c l o h e x - 3 - e n e c a r b o x y l i c  acid  (55) i n e t h e r  carboxylic (26.7  acid  (25 m l ) p r e p a r e d  Excess o x a l y l  d r y b e n z e n e and e v a p o r a t i n g  with dried  overnight the r e a c t i o n mixture  s a t u r a t e d aqueous ammonium a c e t a t e  e t h e r l a y e r was s e p a r a t e d  twice with ether.  solution,  3'-enyl)-1-(4'-methylcyclohex-3'-enyl  O  twice  pressure  1-(4-methylcyclohex-  c a r b o x y ) - 5-methylhex-4-ene  ( 1 1 . 4 g, 35.01) as a c o l o u r l e s s o i l , b.p. 157-166°C ' (0.1 (liquid  mSLX  was  once w i t h b r i n e and  o f the ether at reduced  gave a y e l l o w o i l w h i c h was d i s t i l l e d t o g i v e  (68)  After  solution.  The c o m b i n e d e t h e r l a y e r s were w a s h e d  Evaporation  4  adding  and t h e aqueous p h a s e e x t r a c t e d  2% aqueous s o d i u m b i c a r b o n a t e (Na2S0 ).  c h l o r i d e was r e m o v e d by  in. v a c u o t o g i v e a y e l l o w o i l .  a t room t e m p e r a t u r e  w o r k e d up b y a d d i n g The  4-methylcyclohex-3-ene-=  ( 5 5 ) ( 2 6 . 6 g, 0.19 m o l e ) and o x a l y l c h l o r i d e  g, 0.21 m o l e ) .  stirring  from  film)  mm).  2915 , 1730 , 1440 , 1170 , 920 , 835 , 805 , 770 ,  cm" ; T ( C C 1 ) 4.68 ( s , 2H) , 4.80- 5.40 (m, 2H) , 7.20- 8.27 (m, 18H) , 1  4  8.33 (m,12H); M C  22 34°2' ' H  C  8 0  -  +  0 0  M/e '  3 3 0 ; C, 8 0 . 2 3 ; H, 10.33 ( c a l c . f o r  H,10,30).  2-Methyl-6-keto-6-(4'-methylcyclohex-5'-enyl)-hex-2-ene (a) E t h e r e a l m e t h y l solution,  lithium  solution  5.12 mmole) was a d d e d d r o p w i s e ,  cooling to a solution of methylcyclohex-3'-enyl  (54)  ( 2 1 . 3 ml o f 2.4 M with s t i r r i n g  and  1-(4'methylcyclohex-3'-enyl)-1-(4'-  c a r b o x y ) - 5 - m e t h y l h e x - 4 - e n e (68)  - 81  (4.2  g, 12.8 mmole) i n e t h e r  (15 m l ) .  After stirring.at  t e m p e r a t u r e f o r 0.5 h r w a t e r (50 m l ) was a d d e d . of the ether ether  separation  l a y e r t h e aqueous p h a s e was e x t r a c t e d t w i c e  and t h e c o m b i n e d e t h e r  (Na2S0^).  After  A f t e r evaporation  l a y e r s washed w i t h b r i n e of the ether  room  with  and d r i e d  i n vacuo t h e crude 73  p r o d u c t was d i s s o l v e d i n a c e t o n e (1.65  (10 m l ) a n d J o n e s r e a g e n t  m l ) added d r o p w i s e w i t h s t i r r i n g  and c o o l i n g .  After  a t room t e m p e r a t u r e f o r 0.25 h r t h e r e a c t i o n m i x t u r e by a d d i n g e t h e r the  and w a t e r .  After separation  and t h e c o m b i n e d  l a y e r s w a s h e d w i t h b r i n e , d r i e d (Na2SO^) a n d t h e e t h e r  evaporated a t reduced pressure. yellow  o i l gave  hex-2-ene [lit.  was w o r k e d up  o f t h e two l a y e r s  a q u e o u s p h a s e was e x t r a c t e d t w i c e w i t h e t h e r  ether  stirring  6  3  Distillation  of the r e s u l t i n g  2-methyl-6-keto-6-(4'-methylcyclohex-3'-enyl)-  ( 5 4 ) as a c o l o u r l e s s o i l , b . p . 80-84°C ( 0 . 2 5 mm)  b . p . 123-125°C (2 mm)]. \ )  (liquid  f i l m ) 2905, 1710,  in 3.x  1 4 4 5 , 1 3 7 5 , 9 2 0 , 8 3 5 , 805 c m " ; T ( C C 1 ) 4.63 ( s , 1 H ) , 4.95 Ct, 1  4  J  = 7Hz, 1H),7.20-8.20  (b)  (m, 1 1 H ) , 8.33 ( s , 9 H ) ; M  +  m/e 206.  To t h e a c i d c h l o r i d e o f a c i d ( 5 5 ) p r e p a r e d as above  from  4 - m e t h y l c y c l o h e x - 3 - e n e c a r b o x y l i c a c i d ( 5 5 ) (0.9 g , 6.4 mmole) and  oxalyl  Grignard  c h l o r i d e (0.9 g , 7.0 mmole) was s l o w l y added t h e  c o m p l e x o f b r o m i d e ( 4 9 ) p r e p a r e d as above f r o m 5-bromo-  2-methylpent-2-ene 7.0 mmole). for  ( 4 9 ) ( 1 . 0 5 g , 6.4 mmole) and magnesium  The s o l u t i o n was a l l o w e d  to s t i r  2 h r t h e n w o r k e d up by a d d i n g s a t u r a t e d  acetate  and t h e n e x t r a c t e d t h r e e  was e x t r a c t e d o n c e w i t h s a t u r a t e d solution  times w i t h  a t room  (0.17 g,  temperature  aqueous  ammonium  ether.  The  aqiieous s o d i u m  ether  bicarbonate  t o remove u n c h a n g e d a c i d (55) , t h e n w a s h e d w i t h  brine  - 82 -  and  d r i e d (Na2S0 ).  oil  CO.97 g , 75%) w h i c h was t r e a t e d i n two w a y s : -  Ci)  d i s t i l l a t i o n gave 2 - m e t h y l - 6 - k e t o - 6 - ( 4 ' - m e t h y l c y c l o h e x - 3  enyl)-hex-2-ene in  Removal o f t h e e t h e r i n vacuo gave a y e l l o w  4  (54) i d e n t i c a l  i n a l l respects to that  -  1  obtained  (a) above.  Cii)  Reduction  borohydride  o f a p o r t i o n o f the crude  tentatively  assigned  as  C4 -methylcyclohex-3 -ene) carboxylate 1  1  (liquid  Y  sodium  i n m e t h a n o l , f o l l o w e d b y c h r o m a t o g r a p h y on  gave a p r o d u c t  -tt  o i l with  film)  alumina  4-methylpent-3-enyl ( 7 0 ) as a c o l o u r l e s s o i l .  2915 , 1735 , 1 4 4 5 , 1165 , 830 cm' ; 1  4.67 ( s , 1 H ) , 4.90 ( t , J = 7Hz, 1 H ) , 6.00  TCCC1.)  ( t , J = 7Hz, 2 H ) , 7.33-  Cm, 9 H ) , 8.33 ( s , 9 H ) .  8.20  c < - B i s a b o l o l (46) To iodide  a s o l u t i o n o f methyl  (5 m l ) , was a d d e d  c y c l o h e x - 3 ' - e n y l ) -hex- 2 -ene  for  The m i x t u r e  ( 5 4 ) ( 5 1 . 5 mg, 0.25 mmole) i n e t h e r  was a l l o w e d  to s t i r  The e t h e r  0  ^ (liquid 4  film)  temperature  s a t u r a t e d aqueous  ammonium  and t h e aqueous  The c o m b i n e d e t h e r  washed w i t h b r i n e and d r i e d C N ^ ^ ^ . i n v a c u o gave 0 < - b i s a b o l o l  a t room  l a y e r was s e p a r a t e d  phase e x t r a c t e d t w i c e w i t h e t h e r .  tCCCl )  methyl  2-methyl-6-keto-6-C4'-methyl-  two h o u r s t h e n w o r k e d up b y a d d i n g  acetate solution.  \i  from  ( 1 0 6 . 5 mg, 0.75 mmole) and magnesium powder ( 1 9 . 8 mg, 0.83  mmole) i n e t h e r  (2 m l ) .  magnesium i o d i d e p r e p a r e d  Evaporation  l a y e r s were  o f the ether  ( 4 6 ) (55 mg, 100%) as a c o l o u r l e s s o i l .  3435 , 2 9 1 5 , 1440 , 1 3 7 0 , 1 1 0 5 , 83*0 , 800 c m " ;  4.67 ( s , 1H) , 4.90 ( t , J  1  = 7Hz, 1H) 7.60-8.23 (m, 7H) ,  8.37 C s , 9 H ) , 8 . 5 0 - 8 . 8 7 (m, 5 H ) , 8.93 ( d , J  = 2Hz, 3 H ) ; M  +  m/e 222.  - 83 -  ^-Bisabolene  (4 5)  To ©(-bisabolol  ( 4 6 ) (75 mg, 0.3 mmole) d i s s o l v e d i n p y r i d i n e  (1 m l ) , was a d d e d a s o l u t i o n i n p y r i d i n e (2 m l ) .  o f phosphorus o x y c h l o r i d e (0.5 ml)  The r e a c t i o n m i x t u r e  o v e r n i g h t a n d t h e n w o r k e d up by p o u r i n g by  ether extraction.  with brine, dried give  was a l l o w e d  onto i c e / w a t e r ,  followed  The c o m b i n e d e t h e r e x t r a c t s w e r e w a s h e d  (MgSO^) a n d t h e e t h e r e v a p o r a t e d  i n vacuo to  a y e l l o w o i l (45.6 mg, 7 5 % ) . P u r i f i c a t i o n o f t h i s  preparative very  similar  r e t e n t i o n times.  The l e s s v o l a t i l e (45) ; " 0 - j >  ma  C  (liquid  1440 , 1370 , 1 1 4 5 , 1100 , 910 , 8 2 5 , 800 cm" ;  peak film)  (~"50%) 2935,  ( C C 1 ) 4.67  1  1H),  o i l by  g l c (180°C, 30% C a r b o w a x ) g a v e two c o m p o n e n t s w i t h  was shown t o be ^ - b i s a b o l e n e  (m,  to s t i r  4  (br.s,  4.93 ( t , J - 7 H z , 1 H ) , 7.37 (m, 2 H ) , 8.07 (m, 8 H ) , 8.38 12H) .  The more v o l a t i l e  -bisabolene  peak  ( ~ 5 0 % ) was shown t o be  (53) p l u s o t h e r u n i d e n t i f i e d  i s o m e r ( s ) ,"\) „ m  v  (liquid  Iii ci X.  film)  2940, 1 6 5 0 , 1 4 4 5 , 1 3 7 5 , 9 2 0 , 8 9 0 , 8 3 0 , 800 cm" ; T 1  very s i m i l a r  t o t h e nmr  showing f e a t u r e s isomers 1 4  4  s p e c t r u m o f " t f - b i s a b o l e n e (45) b u t  [ e . g . 5.30 ( s ) j a t t r i b u t a b l e  of ^-bisabolene  (CC1 )  t o d o u b l e bond  (45) .  C - L a b e l l e d Q ( - b i s a b o l o l (46) 14 c<-Bisabolol  (46) was p r e p a r e d  as above u s i n g  C-methyl  iodide  (213.0 mg, 1.5 mmole, lmC, 0.667 mC/mmole) m a g n e s i u m  powder  ( 3 9 . 6 mg , 1.65 mmole) a n d 2 - m e t h y l - 6 - k e t o - 6 - ( 4 ' - m e t h y 1 -  cyclohex-3 -enyl)-hex-2-ene 1  w o r k up so  (54) (103 mg,  0.5 m m o l e ) .  t i c a n a l y s i s showed a t r a c e o f s t a r t i n g  i n a c t i v e methyl  (46) was 110.0 mg  l i t h i u m was a d d e d . (100%),  The y i e l d  and t h e s p e c i f i c  After  k e t o n e (54) l e f t 14 of  C-o<-bisabolol  a c t i v i t y was  determined  - 84 -  to  be 0.37 mC/mmole.  14  v  C-Labelled  p-bisabolene  (45)  14 C-Labelled ot-bisabolol and  the crude  product  as a b o v e  p u r i f i e d by chromatography on a l u m i n a t o  v  14 yield  (55 mg) was d e h y d r a t e d  C - l a b e l l e d o-bisabolene  (45) ( p l u s i s o m e r s )  a colourless o i l . I s o l a t i o n o f T r i c h o t h e c i n (38) from T r i c h o t h e c i u m  (13 mg) as  roseum  T r i c h o t h e c i u m roseum was grown as d e s c r i b e d i n t h e l i t 44 91 erature ' e x c e p t t h a t t h e pH was n o t a d j u s t e d . T r i c h o t h e c i n Q 1  was i s o l a t e d prenarative  as d e s c r i b e d i n t h e l i t e r a t u r e thin  l a y e r c h r o m a t o g r a p h y on s i l i c a  p u r i f i c a t i o n r a t h e r than a typical  experiment  washed w i t h a l i t t l e  (200  that  g e l was u s e d i n t  c o l u m n c h r o m a t o g r a p h y on a l u m i n a .  10 f l a s k s  grow f o r t h r e e w e e k s .  extracted  except  In  o f T. r o s e u m w e r e a l l o w e d t o  The b r o t h was t h e n  filtered,  the m y c e l i a  w a t e r and t h e c o m b i n e d w a s h i n g s and b r o t h  t w i c e , i n 1000 ml p o r t i o n s , w i t h c a r b o n  ml). Evaporation  o f the carbon  tetrachloride  tetrachloride  gave a gum  (148.6 mg) w h i c h was p u r i f i e d by t h i n  l a y e r c h r o m a t o g r a p h y on  silica  ether: ethyl  g e l , developing with petroleum  U n d e r uv r a d i a t i o n approximately off  t h e t r i c h o t h e c i n showed up as a d a r k  h a l f way up t h e p l a t e .  and t h e t r i c h o t h e c i n  Evaporation  o f the e t h y l  w h i c h was r e c r y s t a l l i s e d  These bands were  (38) l e a c h e d w i t h e t h y l  from petroleum  ether  (38) as w h i t e  n e e d l e s , m.p.  m.p.  ( C H C U ) 1715 , 1685 cm" , 1  max  j  (1:1).  band scraped  acetate.  a c e t a t e gave t r i c h o t h e c i n  pure t r i c h o t h e c i n 118°C);^  acetate  ( 3 8 ) ( 9 4 . 3 mg)  (60-80°C) t o g i v e 116-118°C  ( l i t . ^  - 85  T r i c h o t h e c o l o n e " (39) Trichothecin at  ( 3 8 ) (50 mg, 0.15 mmole) was s t i r r e d  room t e m p e r a t u r e  (2 m l ) .  i n IN m e t h a n o l l c  The aqueous l a y e r was t h e n e x t r a c t e d w i t h  removal o f which a t reduced slowly crystallised. petroleum  •v  hydroxide  W a t e r ( 1 . 5 m l ) was t h e n a d d e d a n d t h e m e t h a n o l  i n vacuo.  (39.8  potassium  overnight  ether  pressure  solution evaporated  chloroform,  gave a c o l o u r l e s s gum w h i c h  T h i s was r e c r y s t a l l i s e d  from benzene-  (60-80°C) ( 2 : 1 ) t o g i v e t r i c h o t h e c o l o n e ( 3 9 )  mg, 100%) as w h i t e  n e e d l e s , m.p. 182-184°C ( l i t .  4  6  183-184°C).  ( C H C 1 ) , 3 5 6 0 , 1680 cm" . 1  m a x  3  14 Feeding  of  v C - l a b e l l e d o-bisabolene  A w e l l shaken mixture (13 mg, 0.024 mC) w a t e r distributed After  (5ml)  among 5 f l a s k s  3 weeks t r i c h o t h e c i n  tallized  to constant  1 4  roseum  C - l a b e l l e d ^ - b i s a b o l e n e (45)  a n d Tween 20 ( 0 . 5 m l ) was e v e n l y  o f 1 week o l d c u l t u r e s o f T. r o s e u m . ( 3 8 ) was i s o l a t e d  specific  representing a specific trichothecin  of  (45) t o T r i c h o t h e c i u m  activity  as b e f o r e  and r e c r y s -  ( 1 . 8 8 x 10 ^ mC/mmole)  i n c o r p o r a t i o n o f 0.005%.  The r e m a i n i n g  ( 3 8 ) was h y d r o l y z e d as above t o g i v e t r i c h o t h e c o l o n e  (39) w i t h s p e c i f i c  activity  o f 1.15 x 10  5  mC/mmole r e p r e s e n t i n g  l o s s o f 40% o f t h e r a d i o a c t i v i t y . D i h y d r o - f t - i o n o n e (79) ^3 - I o n o n e  ( 7 8 ) ( 1 9 . 2 g, 0.1 m o l e ) was h y d r o g e n a t e d i n e t h a n o l  (50 m l ) u s i n g Raney n i c k e l  (^4  g) as c a t a l y s t .  A f t e r uptake o f  t h e t h e o r e t i c a l v o l u m e o f h y d r o g e n t h e c a t a l y s t was removed b y filtration, distilled  the ethanol evaporated  to give a product  i n vacuo and t h e r e s u l t i n g o i l  ( 1 4 . 0 g, 72%) w h i c h was homogeneous  - 86 -  on one g l c c o l u m n (175°C, 101 Carbowax) b u t was  shown t o c o n s i s t  of  column  2 products i n the r a t i o  dihydro-/3-ionone 7  8  (79) as a c o l o u r l e s s  (150°C,  (CC1 )  - 1  ( s , 6H); M  7.68  4  m/e  +  (liquid  (m, 4 H ) , 7.94  f i l m ) 2940,  ( s , 3 H ) , 8.43  194; C,80.59; H, 11.48  (calc. for C  C, 80.35 ; H, 1 1 . 4 1 ; and t e t r a h y d r o - p - i o n o n e (  8  0  ) ; ^  m  a  1 5  ( s , 3H), H  9.13  ( d , J = 7 Hz, 3H); M  +  Methyl monocycTofarnesate E t h e r washed m o l e NaH) acetate  was  m/e  (liquid  x  196.  (8 2)  added t o d r y benzene  (81) (1.82 g, 0.01 m o l e ) ,  dihydro-/S-ionone added d r o p w i s e w a t e r was  After stirring  (50 m l ) , and i n benzene  and t h e s o l u t i o n r e f l u x e d  Distillation  o i l , b.p.  3H), C  8.97  16 26°2 H  :  f o r 15 h r .  4  ( s , 6H); M C  >  7 6  '  7 6  > > H  +  m/e  cm" ;  ( s , 2 H ) , 7.84  On  1  was  cooling,  i n vacuo.  (liquid T(CC1 ) 4  571) film) 4.37  ( s , 3 H ) , 8.38 ( s ,  250; C, 77.16; H, 10.59  10-47).  (5 m l )  (82) (1.0 g,  81-83°C (0.02 mm) ; ""O  ( s , 3 H ) , 7.80  f o r 0.5 h r ,  3 times w i t h  ( M g S 0 ) and e v a p o r a t e d  2935, 1 7 2 0 , 1 6 4 5 , 1 4 3 0 , 1355, 1 2 2 0 , 1140 ( b r . s , 1 H ) , 6.37  trimethylphosphono-  i n benzene  gave m e t h y l m o n o c y c l o f a r n e s a t e  as a c o l o u r l e s s  0.01  (5 m l ) , a d d e d a t  a d d e d and t h e r e s u l t i n g o i l e x t r a c t e d dried  (.0.48 g,  a t room t e m p e r a t u r e  (79) (1.35 g, 0.007 m o l e ) ,  e t h e r , t h e e t h e r was  7.70  ( d , J = 5Hz, 6 H ) ,  501 s o d i u m h y d r i d e / o i l d i s p e r s i o n  room t e m p e r a t u r e .  0:  2 2  4  ( s , 3 H ) , 8.33-8.93 (m, 1 0 H ) , 9.07  mm) 1725,  f i l m ) v e r y s i m i l a r t o t h a t o f d i h y d r o - ^ - i o n e ( 7 9 ) ; *£ ( C C 1 ) (m, 2 H ) , 7.95  gave  o i l , b.p. 115-116°C (9  b.p. 122-122.5°C (12 mm)];\)  1 3 6 0 , 1155 c m ; 9.00  on a s e c o n d  S e p a r a t i o n o f t h e s e two compounds (200°C, 3 0 % QFI)  5% Q F I ) .  [lit.  o f <^9:1  (calc. for  - 87 -  Monocyclofarncsol  (47)  L i t h i u m aluminium hydride a s o l u t i o n o f methyl in  ether  (30 mg, 0.79 mmole) was a d d e d t o  monocyclofarnesate  (10 m l ) . The r e s u l t i n g  (82) (300 mg, 1.2 mmole)  s o l u t i o n was s t i r r e d  and w o r k e d up b y p o u r i n g o n t o i c e / d i l u t e HC1. separated The  overnight  The e t h e r l a y e r was  and t h e aqueous l a y e r was e x t r a c t e d 3 t i m e s w i t h  ether.  combined e t h e r e x t r a c t s were washed t h o r o u g h l y w i t h b r i n e ,  dried  (MgSO^) a n d t h e e t h e r e v a p o r a t e d  farnesol  in v a c u o t o g i v e m o n o c y c l o -  ( 4 7 ) , 252 mg, 95%) as a c o l o u r l e s s o i l , \ )  (liquid  film)  3350, 2 9 4 0 , 1 6 7 0 , 1 4 6 0 , 1 3 8 0 , 1 1 1 0 , 1000 c m " ; ~£ ( C C 1 ) 4.64 1  4  (t,  J = 7 H z , 1 H ) , 5.98 ( d , J = 7 H z , 2 H ) , 8.99 ( s , 6 H ) ; M  +  m/e  222. 1 4  C-Tabelled  monocyclofarnesol  l- C-Methyl 1 4  bromoacetate  mmole), t r i m e t h y l p h o s p h i t e were r e f l u x e d f o r 5 h r . washed sodium h y d r i d e  Dihydro-^-ionone  ( 8 3 ) (306 mg, 2 mmole, 1 mC, 0.5  (248 mg, 2 mmole) a n d b e n z e n e  On c o o l i n g , b e n z e n e  (1 m l )  (4 m l ) a n d p e n t a n e  to s t i r  a t room t e m p e r a t u r e  ( 7 9 ) 388 mg, 2 mmole) i n b e n z e n e  f o r 1.5  (5 m l ) was  t h e n added and t h e s o l u t i o n a l l o w e d t o r e f l u x o v e r n i g h t . reaction mixture  mC/  (501 o i l d i s p e r s i o n ) (240 mg, 5 mmole) w e r e  added a n d t h e s o l u t i o n a l l o w e d hr.  (47)  The  was w o r k e d up b y a d d i n g w a t e r f o l l o w e d b y e t h e r  e x t r a c t i o n t o g i v e a y e l l o w o i l w h i c h was p u r i f i e d b y c h r o m a t o g r a p h y on s i l i c a . 6 0 C ) / b enzene u  (171 mg). was s t i r r e d  The f r a c t i o n e l u t i n g w i t h p e t r o l e u m  (3:1) c o n s i s t e d o f methyl  Methyl  monocyclofarnesate  i n ether  ether (40-  monocyclofarnesate  (82)  (82) ( 1 7 1 mg, 0.68 mmole)  (10 m l ) w i t h l i t h i u m  aluminium h y d r i d e (17.1  ^ 88 -  mg, 0.45 mmole) f o r 10 h r . adding  d i l u t e HC1 f o l l o w e d b y e t h e r e x t r a c t i o n  o f t h e e t h e r -to g i v e The  The r e a c t i o n m i x t u r e was w o r k e d up by-  specific  1 4  and e v a p o r a t i o n  C - l a b e l l e d monocyclofarnesol  a c t i v i t y was d e t e r m i n e d  ( 4 7 ) (110 mg).  t o be 0.29 mC/mmole.  14 Feeding  of  C - l a b e l l e d monocyclofarnesol  (47) t o T r i c h o t h e c i u m  roseum A well (55.0  shaken mixture  of  mg, 0.071 mC), w a t e r  distributed  1 4  C - l a b e l l e d monocyclofarnesol  (18 m l ) and Tween 20 (2 m l ) was  among 10 f l a s k s  u s u a l manner and r e c r y s t a l l i z e d  The  5  remaining  evenly  o f 7 d a y o l d c u l t u r e s o f T. r o s e u m .  A f t e r a f u r t h e r 24 d a y s t h e t r i c h o t h e c i n  (0.867 x 10  (47)  ( 3 8 ) was i s o l a t e d  to constant  specific  i nthe  activity  mC/mmole), r e p r e s e n t i n g an i n c o r p o r a t i o n o f 0.003%. trichothecin  trichothecolone  ( 3 8 ) was h y d r o l y z e d  (39) w i t h s p e c i f i c  activity  as above t o g i v e  o f 0.237 x 10  5  mC/  mmole r e p r e s e n t i n g l o s s o f 70% o f t h e r a d i o a c t i v i t y . G e r a n y l b r o m i d e (89) To and  a stirred  carbon  s o l u t i o n o f g e r a n i o l ( 9 2 ) ( 3 0 . 8 g, 0.2 m o l e )  tetrabromide  ( 9 9 . 6 g, 0.3 m o l e ) i n e t h e r  was a d d e d , w i t h s t i r r i n g , (57.6 The  a solution of triphenyl  g , 0.22 m o l e ) i n e t h e r  (200 m l ) , o v e r  r e a c t i o n m i x t u r e was a l l o w e d  was e v a p o r a t e d  a t reduced  was a d d e d t o p r e c i p i t a t e filtered  off.  to s t i r  pressure.  (200 m l )  phosphine  a p e r i o d o f 0.5 h r .  overnight  Petroleum  then  ether  the ether  (60-80°C)  t r i p h e n y l p h o s p h i n e o x i d e w h i c h was  The p e t r o l e u m  e t h e r was e v a p o r a t e d  give  a y e l l o w o i l w h i c h was d i s t i l l e d  (89)  ( 2 7 . 1 g , 62.5%) as a c o l o u r l e s s o i l ,  i n vacuo t o  to give g e r a n y l bromide b . p . 100-108°C  ( 1 1 mm).  - 89 -  -\)  (liquid  v  film)  2940, 1 6 6 0 , 1440 , 1 3 7 5 , 120.0, 840,. 670 cm  t T ' ( C C l ) 4.45 ( t , J = 8 H z , 1 H ) , 4.94 ( b r . s , 4  1H) , 6.07  ;  (d, J =  8 H z , 2 H ) , 7.92 ( d , J = 3 H z , 4 H ) , 8.23-8.43 (m, 9 H ) . Ethyl  2-acetyl-5,9-dimethyldeca-4,8-dienoate Ethyl  acetoacetate  (91)  ( 9 0 ) ( 1 6 . 4 g, 0.126 m o l e ) was added t o  an e t h a n o l i c s o l u t i o n o f s o d i u m e t h o x i d e p r e p a r e d (2.9  g, 0.126 m o l e ) and e t h a n o l  allowed (89) to  to reflux  for 1 hr.  (55 m l ) and t h e s o l u t i o n was  On s l i g h t  c o o l i n g g e r a n y l bromide  ( 2 7 . 1 g, 0.126 m o l e ) was a d d e d a n d t h e m i x t u r e was  reflux  a further 5 hr.  The e t h a n o l was removed  p r e s s u r e , w a t e r a d d e d and t h e o i l y p r o d u c t portions  of ether.  with brine, dried  (MgSO^) and t h e e t h e r e v a p o r a t e d  b.p. 100-102°C  ( 0 . 0 3 mm). ^ 1  4  2H),  washed  i n vacuo t o  2-acetyl-5,9-  ( 9 1 ) ( 1 2 . 9 g, 44%) as a c o l o u r l e s s  1715, 1150 , 1030 cm" ; ' X ' ( C C 1 ) (q,  a t reduced  The e t h e r s o l u t i o n was t h o r o u g h l y  dimethyldeca-4,8-dienoate  allowed  extracted with 3  g i v e an o i l w h i c h was d i s t i l l e d t o g i v e e t h y l  oil,  from sodium  (liquid  film)  2905, 1 7 4 0 ,  4.97 ( t , J = 7 Hz, 2 H ) , 5.85  J = 7 H z , 2 H ) , 6.71 ( t , J = 7 H z , 1 H ) , 7.54 ( t , J = 7.5 H z , 7.85 ( s , 3 H ) , 8.02 ( d , J = 3 H z , 4 H ) , 8.36 (m, 9 H ) , 8.72  ( t , J = 7 Hz, 3H); M  +  m/e 266.  4,8-Dimethylhexa-3,7-dienyl Ethyl  sodium hydroxide  with stirring,  aqueous  ketone  ( g e r a n y l a c e t o n e ) (88)  2-acetyl-5,9-dimethyldeca-4,8-dienoate  0.047 m o l e ) ,  acidified  methyl  (lOg) and w a t e r  at~100°C o v e r n i g h t .  (91) ( 1 2 . 5 g,  (20 m l ) w e r e  The s o l u t i o n was  heated,  carefully  ( l i t m u s ) w i t h 6N h y d r o c h l o r i c a c i d s o l u t i o n and t h e l a y e r e x t r a c t e d 3 times w i t h e t h e r .  s o l u t i o n s were washed w i t h b r i n e , d r i e d  The c o m b i n e d  ether  (MgSO.) and t h e e t h e r  - 90 -  evaporated at reduced pressure to  give  (88)  t o g i v e a r e d o i l w h i c h was  4,8-dimethylhexa-3,7-dienyl methyl ketone  distilled  (geranyl  acetone)  ( 6 . 5 g, -71.5%) as a c o l o u r l e s s o i l , b . p . 64-65°C ( 0 . 1 5  [ l i t . ° 122-122.5°C(12mm)]. ^ 1155,  830 cm" ; %  7.97  ( s , 3 H ) , 8.04  ( C C 1 ) 4.97  1  Nerol  m  a  x  (liquid  f i l m ) 2915 , 1720 , 1 3 5 5 ,  ( t , J = 6 H z , 2 H ) , 7.69  4  ( s , 4 H ) , 8.38  mm)  ( d , J = 4 Hz, 9H); M  (m, 4 H ) , +  m/e  194.  (98) To a s o l u t i o n o f m e t h y l t r i p h e n y l p h o s p h o n i u m b r o m i d e (25.7 g,  0.1 m o l e ) i n t e t r a h y d r o f u r a n solution  (100 ml) was  (42.0 ml o f 2.4 M h e x a n e s o l u t i o n ,  formation  of the r e d y l i d e  5-methylhept-5-en-2-one stirring  t h e s o l u t i o n was  After  t o -78°C and After  allowed  a t room t e m p e r a t u r e o v e r n i g h t .  2.4M  a d d e d and t h e s o l u t i o n a l l o w e d  t o warm up t o 0°C when p a r a f o r m a l d e h y d e  separated  cooled  lithium  l i t h i u m s o l u t i o n (42.0 m l o f  0.1 m o l e ) was  The r e a c t i o n was  0.1 m o l e ) .  (93) ( 1 2 . 6 g, 0.1 m o l e ) a d d e d .  f o r 5 minutes n-butyl  hexane s o l u t i o n ,  added.  added n - b u t y l  (18.0 g, 0.2 m o l e )  t o s t i r a t 0°C W a t e r was  was  f o r 0.5 h r and  added, the l a y e r s  and t h e aqueous l a y e r e x t r a c t e d 3 t i m e s w i t h  ether.  The c o m b i n e d e t h e r s o l u t i o n s were w a s h e d w i t h b r i n e , d r i e d (MgSO^) and  the e t h e r  w h i c h was ^30%  nerol  e v a p o r a t e d i n vacuo t o g i v e  an o i l (10 g, 65%)  shown by g l c a n a l y s i s (130°C, 3% Se 30) t o c o n s i s t o f ( 9 8 ) . A s a m p l e was p u r i f i e d by p r e p a r a t i v e g l c  (180°C, 30% Se 30) and f o u n d t o be i d e n t i c a l w i t h n a t u r a l n e r o l , "\) 1375, (br.s,  1000 , 830 cm" ; 1  1 H ) , 6.04  (liquid  f i l m ) 3345, 2925 , 1680 , 1445 ,  T ? ( C C 1 ) 4.62 4  i n a l l respects  ( t , J = 6 Hz,- 1H) , 4.94  ( d , J = 7 H z , 2 H ) , 7.95  ( d , J = 4 Hz, 4H),  - 91 Methyl  f a m e s ate (100)  Trimethyl  phosphite  (248 mg, 2.0 m m o l e ) , m e t h y l b r o m o a c e t a t e  ( 8 3 ) ( 3 0 6 mg,'2.0 mmole) and b e n z e n e Benzene  (10 m l ) and s o d i u m h y d r i d e  (1 ml) w e r e r e f l u x e d (50% o i l d i s p e r s i o n )  3.0 mmole NaH) w e r e added a n d t h e m i x t u r e for  1.5 h r .  give methyl farnesate  1220,  (3 ml) was added and t h e m i x t u r e  The e t h e r was w a s h e d w i t h b r i n e ,  evaporated i n vacuo  b.p.  ( 8 8 ) (388 refluxed  W a t e r was a d d e d and t h e aqueous l a y e r e x t r a c t e d 3  times w i t h ether. and  (144 mg,  a t room t e m p e r a t u r e  4,8-Dimethylhexa-3,7-dienyl methyl ketone  mg, 2.0 mmole) i n b e n z e n e overnight.  stirred  f o r 24 h r .  to give  (MgSO^)  an o i l w h i c h was d i s t i l l e d t o  ( 1 0 0 ) (305 mg, 61%) as a c o l o u r l e s s o i l ,  55°C ( 0 . 1 mm) /\) 1145 c m " ; T  dried  (liquid  film)  2925 , 1720 , 1650 , 1 4 3 5 ,  ( C C 1 ) 4.40 ( s , 1 H ) , 4.94 ( t , J = 6 H z , 2 H ) ,  1  4  6.37 ( s , 3 H ) , 7.87 ( s , 3 H ) , 8.37 ( d , J = 4 H z , 9 H ) ; M  +  m/e 250.  F a r n e s o l (99) Methyl  farnesate  aluminium hydride stirred  ( 1 0 0 ) (430 mg, 1.74 m m o l e ) , l i t h i u m  ( 4 3 mg, 1.13 mmole) and e t h e r  a t room t e m p e r a t u r e f o r 4 h r .  aqueous l a y e r e x t r a c t e d 3 t i m e s w i t h was w a s h e d w i t h b r i n e , give farnesol  dried  W a t e r was a d d e d and t h e  ether.  The e t h e r  solution  (MgSO^) and t h e e t h e r e v a p o r a t e d t o  ( 9 9 ) (367 mg, 95%) as a c o l o u r l e s s  in a l l respects with natural  (10 m l ) w e r e  farnesol, ~\3  m a x  o i l identical  (liquid  film)  3335,  2905, 1670 , 1440 , 1370 , 9 9 5 , 835 cm" ; T ( C C 1 ) 4.63 ( t , J = 1  4  6 H z , 1 H ) , 4.92 ( b r . s , 2 H ) , 5.98 ( d , J = 7 H z , 2 H ) , 7.23 1H),  7.97 ( t , J = 3  H z , 8 H ) , 8.37 ( d , J = 4 H z , 1 2 H ) .  (br.s,  - 92 -  Farnesol-10,11-epoxide To  farnesol  aqueous glyme  (48)  ( 9 9 ) (300 mg, 1.35 mmole) d i s s o l v e d  ( 1 3 . 9 m l ) was added N - b r o m o - s u c c i n l m i d e  2.70 mmole) i n 70% aqueous glyme stirred  a t room t e m p e r a t u r e  aqueous l a y e r was e x t r a c t e d methylene  ( 3 . 5 m l ) . The m i x t u r e was  3 times w i t h  c h l o r i d e was w a s h e d w i t h  i n methanol  was e x t r a c t e d washed w i t h  film)  dried  dried  methylene  was ( 1 5 1 mg, stirred  The aqueous  c h l o r i d e w h i c h was  layer  then  (MgSO^) and e v a p o r a t e d i n v a c u o t o g i v e  ( 4 8 ) (280 mg, 87%) as a c o l o u r l e s s o i l ,  3310 , 2840 , 1 6 4 0 , 1 4 2 5 , 1360 , 1 1 1 0 , 1 0 0 0 ,  Hid-A.  870  (MgSO^) a n d  The s o l u t i o n was added.  The  c h l o r i d e , the  The c r u d e b r o m o h y d r i n  f o r 1 h r then water  farnesol-10,11-epoxide (liquid  brine,  (1 m l ) a d d e d .  3 times w i t h  brine,  methylene  ( 9 . 5 m l ) and p o t a s s i u m h y d r o x i d e  2.70 mmole) i n m e t h a n o l a t room t e m p e r a t u r e  (480 mg,  f o r 1 h r t h e n w a t e r was a d d e d .  evaporated at reduced p r e s s u r e . dissolved  i n 701  (  cm" ; 1  T(CC1 ) 4  4.63 ( t , J = 6 H z , 1H) , 4.87 ( b r . s , 1H) , 5.98  ( d , J = 6 H z , 2 H ) , 6.43 ( b r . s , 1H) 7.47 ( t , J = 6 H z , 1 H ) , 7.97 ( t , J = 4 H z , 6 H ) , 8.37 ( d , J = 4 H z , 8 H ) , 8 . 7 6 . ( d , J = 3 H z , 6H) . 14 C-Labelled  farnesol  Trimethyl acetate  phosphite  (248mg, 2 m m o l e ) , l - ^ C - m e t h y l 1  f o r 24 h r .  (10 m l ) a d d e d .  The s o l u t i o n was c o o l e d and  Sodium h y d r i d e  (50% o i l d i s p e r s i o n )  (144 mg, 3 mmole) was a d d e d and t h e m i x t u r e s t i r r e d temperature benzene  bromo-  ( 8 3 ) (306 mg, 2 mmole, 1 mC, 0.5 mC/mmole) and b e n z e n e  ( 1 ml) were r e f l u x e d benzene  e p o x i d e (48)  for 1 hr.  Geranyl acetone  a t room  ( 8 8 ) (388 mg, 2 mmole) i n  (3 m l ) was added and t h e s o l u t i o n r e f l u x e d  f o r 24 h r .  -  93  -  Examination of the r e a c t i o n mixture r e a c t i o n h a d o n l y gone a p p r o x i m a t e l y product and  by g l c i n d i c a t e d t h a t 50% s o t h e c r u d e r e a c t i o n  was added t o h a l f m o l a r e q u i v a l e n t s  trimethylphosphonoacetate(81).  to r e f l u x  A f t e r a l l o w i n g the r e a c t i o n  with ether.  The e t h e r  w i t h b r i n e , d r i e d (MgSO^) and t h e e t h e r pale yellow  (100) p r e p a r e d  above.  (500 mg, 2mmole), l i t h i u m  mmole) and e t h e r  (10 m l ) w e r e s t i r r e d  l a y e r was w a s h e d  evaporated to give a  o i l (500 mg, 100%) i d e n t i c a l  methyl farnesate  hr.  hydride  f o r a f u r t h e r 24 h r , w a t e r was a d d e d and t h e aqueous  l a y e r e x t r a c t e d 3 times  farnesate  o f sodium  i n a l l respects 1 4  with  C - l a b e l l e d methyl  aluminium hydride  (50 mg,  a t room t e m p e r a t u r e f o r 10  D i l u t e HC1 was added and t h e aqueous l a y e r e x t r a c t e d 3  with ether.  The e t h e r  (MgSO^) and t h e e t h e r mg, 96%) i d e n t i c a l  1.4  times  l a y e r s were washed w i t h b r i n e , d r i e d e v a p o r a t e d t o g i v e a c o l o u r l e s s o i l (426  i n a l l respectswith natural farnesol(99).  14 To  C - l a b e l l e d f a r n e s o l (426 mg, 1.92 mmole) i n 70% aqueous  glyme ( 1 9 . 7 m l ) was added N - b r o m o s u c c i n i m i d e i n 70% aqueous glyme a t room t e m p e r a t u r e f o r  ( 5 . 0 m l ) . The m i x t u r e  (682 mg, 3.84 mmole) was a l l o w e d  2 h r t h e n w a t e r was a d d e d .  l a y e r was e x t r a c t e d 3 t i m e s  to s t i r  The aqueous  w i t h methylene c h l o r i d e , the  m e t h y l e n e c h l o r i d e w a s h e d w i t h b r i n e , d r i e d (MgSO^) and e v a p o r a t e d i n vacuo to give and  an o i l w h i c h was d i s s o l v e d i n m e t h a n o l  potassium hdroxide  added.  (206 mg, 3.84 mmole) i n m e t h a n o l  The s o l u t i o n was s t i r r e d  then water added.  (1.4 m l )  a t room t e m p e r a t u r e f o r 2 h r  The aqueous l a y e r was e x t r a c t e d 3 t i m e s  methylene c h l o r i d e , t h e m e t h y l e n e c h l o r i d e washed w i t h dried  (13.5 ml)  (MgSO^) and e v a p o r a t e d a t r e d u c e d p r e s s u r e  (394.7 mg, 86.5%) i d e n t i c a l  i n a l l respects with  with  brine,  t o g i v e an o i l farnesol-10,11-  - 94 -  epoxide  (48) p r e p a r e d  as a b o v e .  The s p e c i f i c  activity  was  d e t e r m i n e d t o be 0.10 mC/mmole. 14 Feeding o f  C-labelled  farnesol-10,11-epoxide  (48) t o T r i c h o t h e c i u m  roseum A well  shaken mixture o f ^ C - l a b e l l e d  farnesol-10,11-epoxide  (102.7 mg, 0.041 mC), w a t e r (18 m l ) and Tween 20 (2 m l ) was e v e n l y distributed After  among 15 f l a s k s  a further  o f 4 day o l d c u l t u r e s o f T.  2 weeks t r i c h o t h e c i n  u s u a l manner and r e c r y s t a l l i s e d (0.670 x 10  5  The r e m a i n i n g  ( 3 8 ) was i s o l a t e d  to constant s p e c i f i c  roseum. i n the  activity  mC/mmole), r e p r e s e n t i n g an i n c o r p o r a t i o n o f 0.0071. t r i c h o t h e c i n was h y d r o l y s e d as a b o v e t o g i v e  trichothecolone  (39) w i t h s p e c i f i c  mmole r e p r e s e n t i n g l o s s  of over  activity  o f 0.317 x 1 0 '  50% o f t h e r a d i o a c t i v i t y .  5  mC/  - 95 BIBLIOGRAPHY  1.  J . N. 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S o c , 1960 , '82, Letters, Letters, J.C.S.  1972, 1969.  1 9 5 5 , 1 2 , 213.  PART I I  ATTEMPTED CYCLISATION OF A C Y C L I C ENOL ACETATES  - 100 -  INTRODUCTION For  many y e a r s c h e m i s t s h a v e b e e n i n t e r e s t e d  i n attempting to  s y n t h e s i s e n a t u r a l p r o d u c t s by r o u t e s w h i c h b e a r a resemblance t o either of  a proven o r a p o s t u l a t e d b i o s y n t h e t i c pathway.  t h o s e s y n t h e s e s was p r o b a b l y C o l l i e ' s  from d e h y d r o a c e t i c a c i d ( 2 ) .  OH  synthesis  The  first  o f o r c i n o l (1)  1  0  A review of biogenetic covering the l i t e r a t u r e  type s y n t h e s e s has been p u b l i s h e d  t o 1961, and a f u r t h e r r e v i e w  covering  3 developments  4  i n the terpene area i s i n the press.  has  c l a s s i f i e d b i o g e n e t i c type syntheses i n t o  (a)  Amphosynthesis,  Van T a m e l e n  three categories:  w h i c h i s a spontaneous, non-enzymic  w h i c h p r o c e e d s by t h e same m e c h a n i s m i n v i v o (b) B i o - o r g a n i c s y n t h e s i s , w h i c h i s a n o n - e n z y m i c  reaction  as i n v i t r o . transformation  c a r r i e d o u t on a compound, w h i c h i s v e r y s i m i l a r  to a  n a t u r a l s u b s t r a t e , t o g i v e a compound v e r y s i m i l a r t o the (c)  n a t u r a l p r o d u c t formed by the enzymic  Chemical Analogue sequence  of a Biosynthesis, which i s a synthetic  roughly patterned after  Many r e s e a r c h g r o u p s  reaction.  are i n v o l v e d  a biological  sequence.  i n attempting biogenetic-  t y p e s y n t h e s e s , and s o m e t i m e s t h e f a c i l i t y  of a reaction  leads to  - 101 proposals  concerning  convenient  -  b i o s y n t h e t i c pathways.  s y n t h e s i s o f camphor  acetate  (4) has  camphor  (3) c o u l d o c c u r by  a enol  t h a t the b i o s y n t h e s i s of  a s i m i l a r type  derivative.  example  (3) f r o m d i h y d r o c a r v o n e  prompted the s u g g e s t i o n  an e n o l p h o s p h a t e  For  o f r e a c t i o n , e.g.  via  5  OAc BF^/CH CI ?  9  (3)  (4) In  an  attempt to expand the scope of t h i s  enol acetates 6 conditions.  ( 5 ) - ( 7 ) were p r e p a r e d  and  r e a c t i o n other  subjected to  7 '  I t was  found that enol acetates  (5) and  c y c l i s e d s m o o t h l y t o g i v e camphor d e r i v a t i v e s (8) and that enol  cyclising  acetate  (6)  [9)  but  ( 7 ) , w h i c h i t was  hoped would g i v e the n a t u r a l l y 8 o c c u r r i n g s e s q u i t e r p e n e c a m p h e r e n o n e [10) gave a m i x t u r e o f 9 p r o d u c t s , the n a t u r e of w h i c h i s at p r e s e n t under i n v e s t i g a t i o n . 10 C o r e y and c o - w o r k e r s have used the c y c l i s a t i o n of e n o l a c e t a t e (11) i n a s y n t h e s i s o f c e d r o l (12) w h i c h c l o s e l y f o l l o w s 11 the proposed b i o s y n t h e s i s of c e d r o l . In  an  attempt to t e s t  cyclisation  r e a c t i o n i t was  acetate  see  that  the  and  the g e n e r a l i t y of the e n o l decided  i f i t c o u l d be  r e a c t i o n s h o u l d be  to prepare  cyclised.  planned  an  acetate  acyclic  F u r t h e r i t was  so t h a t i t h a d  some  enol decided feasibility  - 103 -  as a b i o s y n t h e t i c r o u t e . of-cuparenone  The  compound c h o s e n f o r s y n t h e s i s  (13) and t h e r e q u i r e d e n o l  acetate  i s compound  was (14) .  (13) (14) (+)Cuparenone  i s a n a t u r a l product which i s found i n the 12  essential is  o i l o f "mayur p a n k h i " ,  as d e p i c t e d  in (13a).  1 3  and t h e a b s o l u t e  configuration  H o w e v e r , b e f o r e CX-cuparenone  (13)  been r e c o g n i s e d  as a n a t u r a l p r o d u c t i t h a d b e e n s y n t h e s i s e d  an i n t e r m e d i a t e  i n the s y n t h e s i s o f the r e l a t e d  (+)-cuparene  (14).^  In t h i s  synthesis  had as  sesquiterpene  t o l u e n e was  condensed  with  0  (13a)  3-m.ethyl c y c l o h e x - 2 - e n o n e , to give ketone hindered  (14)  i n the presence of aluminium c h l o r i d e ,  ( 1 5 ) , w h i c h was  dimethylated  at the  sterically  2 - p o s i t i o n by p r i o r p r o t e c t i o n o f t h e 6 - p o s i t i o n as  f u r f u r y l i d e n e d e r i v a t i v e (16) .  Ozonolysis  of dimethyl  ketone  the (17)  - 104 gave a d i p i c a c i d  (18) w h i c h , was  condensation, hydrolysed C13).  The o v e r a l l  esterified,  subjected, to  and d e c a r b o j c y l a t e d t o g i v e  I:  C~ \  r e a c t i o n s e q u e n c e i s shown i n F i g u r e I . 5  Figure  Dieckmann  Previous  s y n t h e s i s o f ( X - c u p a r e n o n e (13)  cup a r e none  - 105 DISCUSSION The c y c l i s a t i o n method o f p r e p a r i n g  o f e n o l a c e t a t e s has p r o v i d e d some mono-and s e s q u i t e r p e n e s  a convenient  by r e a c t i o n s w h i c h  5 7 may h a v e a n a l o g y i n n a t u r e . of t h i s key  '  In order  to t e s t the g e n e r a l i t y  r e a c t i o n a s y n t h e s i s o f o(,-cuparenone  s t e p o f w h i c h was c y c l i s a t i o n  manner w h i c h may h a v e s i g n i f i c a n c e  (13) was d e v i s e d , t h e  of enol acetate  (14), i n a  i n t h e b i o s y n t h e s i s o f <X-  cuparenone ( 1 3 ) .  (14) Thus t h e f i r s t efficient  o b j e c t i v e i n t h e s y n t h e t i c scheme was an  s y n t h e s i s of ketone (15).  (15)  - 106 -  R e a c t i o n o f heptenone p_-bromotoluene Analysis (tic)  w i t h the G r i g n a r d complex  gave t e r t i a r y a l c o h o l  (.17}  i n good  o f t h e c r u d e r e a c t i o n p r o d u c t by t h i n  l e d to dehydration of alcohol  p u r i f i e d by c o l u m n i m p u r i t y , w h i c h was  chromatography  (17)  on s i l i c a  layer  chromatography dis-  , t h e p r o d u c t was gel.  eluted with petroleum ether  be 4 , 4 ' - d i m e t h y l b i p h e n y l (18) by a n a l y s i s  of  yield.  showed t h e p r e s e n c e o f a n o n - p o l a r i m p u r i t y , and as  tillation  to  Cl°)  The n o n - p o l a r (40-60°C) was  found  of i t s i n f r a - r e d  (ir)  and n u c l e a r m a g n e t i c r e s o n a n c e . (nmr) s p e c t r a , and i t s m e l t i n g 16 point. I t i s p r e s u m a b l y f o r m e d by n u c l e o p h i l i c d i s p l a c e m e n t o f the  b r o m i n e i n p - b r o m o t o l u e n e by t h e G r i g n a r d c o m p l e x  m o l e c u l e o f p_-bromotoluene.  of another  Such G r i g n a r d c o u p l i n g s have  been  1 7  noted before.  E l u t i o n o f the column w i t h methanol  t h e n gave  pure a l c o h o l (17). OH  (18)  - 107  The  next step  i n the  -  s e q u e n c e was  i n t r o d u c t i o n of the  oxygen  f u n c t i o n which, w o u l d u l t i m a t e l y become t h e k e t o n e g r o u p i n k e t o n e (15).  This  followed  was  by  a c c o m p l i s h e d by  h y d r o b o r a t i o n of a l c o h o l  an o x i d a t i v e w o r k up  using  b a s i c hydrogen  (17)  peroxide  18 solution  to give  crystallised. reactions an  From d i o l  w o u l d be  oxidation  diol  of  C19), (19)  sufficient  the  a. c o l o u r l e s s i t was  syrup which  thought that  to give  secondary hydroxyl  slowly  two  further  k e t o - o l e f i n (15), function,  namely  followed  by  d e h y d r a t i o n o f t h e t e r t i a r y one. d e h y d r a t i o n of t e r t i a r y a l c o h o l s  There i s a p r e c e d e n t f o r of t h i s type e x c l u s i v e l y to  the  alcohol  e x o m e t h y l e n e d o u b l e b o n d , as  (17)  has  been  give  dehydrated  19 with  aqueous o x a l i c a c i d t o g i v e  found that  diol  (19)  could  not  be  diene  (20)  m  However i t  was  smoothly converted i n t o k e t o l  (20)  (21).  - 108 -  (21)  The f i r s t  o x i d a t i v e c o n d i t i o n w h i c h was t r i e d was a J o n e s  20 oxidation. (19)  with  I t appeared that these c o n d i t i o n s concomitant loss of a three  compound t e n t a t i v e l y p e a k a t 1775 cm signal of  1  assigned  over-oxidised  carbon fragment t o give  structure  Such o x i d a t i v e c l e a v a g e s ,  - l a c t o n e s , have been r e p o r t e d  compounds c o n t a i n i n g p a r t  before  structure  (23)  a  (22) on t h e b a s i s o f a  i n t h e i r s p e c t r u m a n d no s a t u r a t e d  i n t h e nmr s p e c t r u m .  diol  (23) .  methyl and  formation  duririg o x i d a t i o n o f 21  - 109  -  O t h e r o x i d a t i v e c o n d i t i o n s which, were t r i e d were the a c t i o n of B-bromosuccinimide water,  m e t h a n o l and  CNBS) i n a s o l v e n t s y s t e m c o n s i s t i n g  ether,  22  NBS  i n aqueous d i o x a n  22  of  and  23 manganese d i o x i d e i n . a c e t o n i t r i l e . gave a c o m p l e x m i x t u r e w h i c h was  t r i e d was  of u n i d e n t i f i e d products. 24  the S a r e t t reagent,  f o r m e d b e t w e e n p y r i d i n e and (19) w i t h t h i s  reagent  was  by  identified  best  low,  slow,  were found  r e a c t i o n was  nmr  very  of products,  the excess  t o be v e r y  one  slow,  and  of  diol  of which  However, at  of reagent  critical:  complex  Reaction  s p e c t r a as k e t o n e ( 2 1 ) . and  reactions  A f u r t h e r method  w h i c h i s the  chromium t r i o x i d e .  gave a m i x t u r e  i r and  t h e r e a c t i o n was  temperature  A l l three of these  and r e a c t i o n  i f e i t h e r was  too  i f too h i g h o v e r - o x i d a t i o n  occurred. As  i t was  into ketol that  found  i m p o s s i b l e to c l e a n l y  C21) , w h i c h c o u l d t h e n be  t h e d e h y d r a t i o n s h o u l d be  later  oxidation.  o f two  performed f i r s t ,  i n the  dehydration.  a c e t i c anhydride  i t was  decided  f o l l o w e d by  a  sequence, namely p r o t e c t i o n of the  a l c o h o l as an a c e t a t e and  acetate after  dehydrated,  (19)  This p l a n , however, n e c e s s i t a t e d the i n t r o d u c t i o n  e x t r a steps  secondary  transform d i o l  ;  subsequent h y d r o l y s i s of  Thus t r e a t m e n t  of d i o l  i n p y r i d i n e gave, i n h i g h y i e l d ,  Q9)  this  with  hydroxy  acetate  (24). 19 Dehydration or w i t h t h i o n y l  of hydroxy acetate  s p e c t r u m ) was  remainder being  2  chloride in pyridine  of which only approximately o f t h e nmr  C 4) 25  c i s - and  one  third  w i t h aqueous o x a l i c  gave a m i x t u r e (as d e t e r m i n e d  the d e s i r e d acetoxy trans - acetoxy  olefin  olefin C26}.  of  acid  olefins,  by a n a l y s i s C25),  the  - 110  -  r^J  Because of the d i s a p p o i n t i n g r e s u l t of the reaction  i t was  decided  an a l t e r n a t i v e r o u t e  t o abandon t h i s  to k e t o - o l e f i n  (15)  reaction  66%  dehydration scheme and  i n which the  devise  exomethylene 70  double on  bond i s p r e p a r e d  some a p p r o p r i a t e l y  by  a stereoselective  functionalised  ketone.  Wittig  reaction'  - I l l I n d e v i s i n g a r e a c t i o n scheme f o r t h e s y n t h e s i s o f k e t o olefin  (15) i n w h i c h the double bond i s p r e p a r e d  reaction, first  by a W i t t i g  and w h i c h f o r c o n v e n i e n c e f o l l o w s i n g e n e r a l  scheme t r i e d ,  n o t i c e must be t a k e n  of several points.  (a) F o r m a t i o n o f t h e k e t o n e w o u l d be b y G r i g n a r d b e t w e e n an a p p r o p r i a t e  olefinic  o u t l i n e the  b r o m i d e and  reaction aromatic  acid chloride. (b) B e f o r e is  hydroboration  t h e k e t o n e must be p r o t e c t e d  s u s c e p t i b l e t o r e d u c t i o n by  .diborane.  ( c ) The a l c o h o l i n t r o d u c e d by t h e h y d r o b o r a t i o n be p r o t e c t e d Taking  into  during  as i t  r e a c t i o n must  the W i t t i g r e a c t i o n .  account those  r e a c t i o n s was a t t e m p t e d .  p o i n t s the f o l l o w i n g sequence o f  Treatment of c y c l o p r o p y l m e t h y l  ketone  w i t h m e t h y l m a g n e s i u m i o d i d e gave c a r b i n o l ( 2 7 ) w h i c h was  smoothly  converted Julia  i n t o b r o m i d e (28) w i t h 48% HBr a f t e r t h e m e t h o d o f 27 and c o - w o r k e r s . Br  (28)  28 During bromide  previous  give  i n v o l v i n g Grignard  (28) w i t h a c i d c h l o r i d e s i t was  complex o f bromide to  work  (28) c o u l d  reactions of  f o u n d t h a t t h e magnesium  reduce the i n i t i a l l y  formed  ketone  a magnesium a l c o h o l a t e w h i c h r e a c t e d w i t h t h e a c i d c h l o r i d e  to  g i v e an e s t e r as t h e m a i n p r o d u c t .  Such r e d u c t i o n s  by  29  Grignard  complexes have p r e c e d e n c e i n the  This  r e a c t i o n c o u l d be a v o i d e d  i.e.  a d d i t i o n of the Grignard  very  great  by v e r y  slow i n v e r s e a d d i t i o n ,  complex to the a c i d c h l o r i d e , but  c a r e h a d t o be t a k e n  to exclude  t r a n s f e r and a d d i t i o n o f t h e G r i g n a r d Grignard  literature.  oxygen d u r i n g the  complex, otherwise  c o m p l e x became o x i d i s e d by m o l e c u l a r  the  oxygen t o g i v e  a n o t h e r magnesium a l c o h o l a t e , w h i c h a g a i n w o u l d r e a c t w i t h t h e acid chloride.  - 113 To a v o i d Grignard alcohol  these  complications  complex o f bromide  i t was d e c i d e d  t o react the  (28) w i t h p_-tolualdehyde  to give  (29) w h i c h c o u l d , i n a s u b s e q u e n t s t e p , be o x i d i s e d t o  give ketone  ( 3 0 ) . However when e q u i m o l a r amounts o f b r o m i d e ( 2 8 ) H  OH  (30) and  p_- t o l u a l d e h y d e  shown by gas l i q u i d  were r e a c t e d  chromatography  none o f w h i c h was p_- t o l u a l d e h y d e hydroxyl  absorption  crude product ir  together  }  was  ( g l c ) t o c o n s i s t o f 3 compounds, b u t w h i c h had a c a r b o n y l  i n the i r spectrum.  gave a p r o d u c t  the crude product  and a  Jones o x i d a t i o n o f t h i s  with a carbonyl  absorption  i nthe  s p e c t r u m b u t w h i c h was shown b y g l c t o c o n s i s t o f 2 compounds.  These were i d e n t i f i e d (30).  as p _ - t o l u a l d e h y d e  and t h e r e q u i r e d  ketone  Thus what a p p e a r e d t o h a v e h a p p e n e d was t h a t t h e f i r s t  f o r m e d magnesium a l c o h o l a t e was r e d u c i n g to p - t o l y l m e t h a n o l  (.31) a n d was i t s e l f  some o f t h e  u-tolualdehyde  o x i d i s e d t o ketone  (30) ,  - 114 the 3 products i n the crude alcohols  (29)  been noted  and  (31).  -  r e a c t i o n product  being ketone  Such r e a c t i o n s of G r i g n a r d  complexes have  3  decided  t o make use  of t h i s  reaction,  and  so  t h e s u b s e q u e n t o x i d a t i v e s t e p , by u s i n g a 2 m o l a r e x c e s s tolualdehyde  ketone  (30)  and  before. ^  I t was  of bromide  (.30)  i n the  Grignard reaction.  Reaction  of the  avoid of  p-  Grignard  (28) w i t h 2 m o l e s o f r j 4 o l u a l d e h y d e gave a m i x t u r e and  c o u l d be  easily  tography  on  p-tolyljnetbanol obtained  silica.  (31)  from which ketone  i n good y i e l d by  distillation  of  (30) and  chroma-  - 115 Ketone  (30) was n e a t k e t a l i s e d  using excess d i o l  r e f l u x i n g benzene withl p_-toluenesulphonic a c i d c a t a l y s t , to give k e t a l hydroxy  ketal  (33) w h i c h was  (34) by t h e a c t i o n  (p_-TSA) as  acid  smoothly converted  into  o f d i b o r a n e f o l l o w e d by  18 hydrogen peroxide  (30)  solution.  (32)  (32) i n  (33)  basic  - 116 Treatment pyridine  of hydroxy k e t a l  gave a c e t o x y k e t a l  C34) w i t h a c e t i c a n h y d r i d e i n  C35) w h i c h was h y d r o l y s e d w i t h  d i l u t e HC1 i n a c e t o n e t o g i v e  a c e t o x y ketone C36).  (36) Reaction o f acetoxy ketone  (36) w i t h  the y l i d e  a c t i o n of sodium m e t h y l s u l p h i n y l m e t h i d e phosphonium bromide olefin  (25).  on m e t h y l  gave, i n d i s a p p o i n t i n g l y  Hydrolysis  d e r i v e d by t h e  of acetoxy-olefin  triphenyl  low y i e l d ,  (25) w i t h  acetoxy  sodium  20 hydroxide s o l u t i o n , alcohol 0  o f the r e s u l t i n g  ( 3 7 ) gave k e t o o l e f i n ( 1 5 ) . -  •  +  CH -S-CH Na 3  f o l l o w e d by Jones o x i d a t i o n  2  +  +  0 P-CH Br 3  3  >  0 -P-CH 3  2  - 117 -  0  M-™2  AcC  +  (36)  NaOH/MeOH/H 0 2  <-  Jones oxidation  (37)  (15) As p r e l i m i n a r y a t t e m p t s acetate  (14), using  of products,  isopropenyl acetate  keto-olefin  CIS) t o enol  a n d p_-TSA, g a v e a m i x t u r e  w i t h rearrangement o f t h e exomethylene double bond,  i t was d e c i d e d prepared  to convert  t o perform  by G r i g n a r d  a model study  on k e t o n e  C38),  r e a c t i o n between i s o b u t y r a l d e h y d e 2  easily and n - b u t y l  0  b r o m i d e , f o l l o w e d by Jones o x i d a t i o n secondary a l c o h o l (39). trityl  lithium  Cprepared  of the intermediate  Treatment o f ketone  (38) w i t h  sufficient  f r o m t r i p h e n y l methane and n - b u t y l  -  118  (38)  lithium) to give a p e r s i s t e n t pink  c o l o u r , f o l l o w e d by  of the e n o l a t e w i t h a c e t i c a n h y d r i d e , acetates  (40)  e s t i m a t e d by  and  (41)  g l c and  in a ratio  nmr  gave a m i x t u r e  of a p p r o x i m a t e l y  spectroscopy.  of  9:1,  This product  quenching enol as  ratio  is  31 c o n s i s t e n t w i t h t h e w o r k o f House and produce enol acetates  of ketone  C38)  Kramer.  Attempts  under a v a r i e t y  to  of m i l d  a c i d c o n d i t i o n s were a l l u n s u c c e s s f u l : (a) T r e a t m e n t o f k e t o n e 3 anhydride reaction.  (38) w i t h p e r c h l o r i c a c i d  i n acetic  2  f o r 6 m i n u t e s a t room t e m p e r a t u r e gave  no  - 119  OAc  (40) (b) T r e a t m e n t o f k e t o n e oxalic  -  (38) w i t h  a c i d a t 110°C  OAc  (41) isopropenyl  acetate  f o r 15 h o u r s gave no  (37)  and  reaction. 33  ( c ) A r e p o r t on  the  s y n t h e s i s o f camphor e n o l  suggested that t h i s acetylating was  p r e p a r e d as  reported  l i t h i u m and  a c e t i c anhydride. acetate  (40)  or  enol  acetate  from  quenching the  i n d i c a t i o n of formation  camphor  enolate (38)  oxalic  of enol  (42)  with with  acid acetates  (41). (38) w i t h i s o p r o p e n y l  acetate  and  by w e i g h t o f p_-TSA g a v e a m i x t u r e o f 3 compounds  s e p a r a t e d by p r e p a r a t i v e nmr  s p e c t r a as  The  relative  by  literature  i n r e f l u x i n g b e n z e n e and  (d) T r e a t m e n t o f k e t o n e 20%  Enol 33  However t r e a t m e n t o f k e t o n e  (42)  o r p_-TSA gave no  i n the  (42)  an e f f i c i e n t  agent under m i l d c o n d i t i o n s .  (4) u s i n g n - b u t y l  enol  compound m i g h t be  acetate  g l c are  enol  acetates  amounts o^  34.8%,  g l c and  31.7%  (40),  (40) , (41) and  i d e n t i f i e d by  33.6%  (41) and  and  i r and  (43).  (43) , as  respectively  estimated  - 120 -  OAc  1) n - B u L i  0  2) A c 0 2  (42)  (4)  w h i c h i s i n t h e same r e g i o n in a study of s i m i l a r  as t h a t  compounds.  f o u n d b y House and K r a m e r  31  - 121 As  attempts  -  to form e n o l a c e t a t e  w e r e s i n g u l a r l y u n s u c c e s s f u l , i t was the m i x t u r e  which c o n s i s t e d mostly  by q u e n c h i n g t h e e n o l a t e Unfortunately  anion  a l l efforts  unsuccessful.  (41) u n d e r m i l d c o n d i t i o n s decided  t o t r y and  of enol acetate  of ketone  (40)  (prepared  (38) w i t h a c e t i c  d i r e c t e d towards t h i s  Thus t r e a t m e n t  isomerise  of the m i x t u r e  anhydride).  g o a l . were a l s o  with perchloric acid  32 in  acetic  anhydride  isomerisation;  f o r 7 m i n u t e s a t room t e m p e r a t u r e gave  treatment  of the m i x t u r e  no  w i t h r e f l u x i n g benzene, i n 34  w h i c h was and  d i s s o l v e d one  treatment  crystal  of the m i x t u r e  of i o d i n e ,  gave no i s o m e r i s a t i o n ;  with isopropenyl acetate  (37)  and  31 p_-TSA  a t 90°C f o r 24 h o u r s gave no i s o m e r i s a t i o n . To  summarise t h i s  acetates acetate (38)  of ketone (41)  (38) v i a e n o l a t e  i n only approximately  under a v a r i e t y  acetate acidic  s e r i e s of r e a c t i o n s , f o r m a t i o n  formation, conditions  and  ( 4 3 ) , and  10%  yield,  treatment [probably  of ketone  enol  treatment  ketone  of  lastly  (38) w i t h more  enol forcing  s t r o n g enough t o i s o m e r i s e  equal  enol acetate  (40)  c o u l d n o t be  to enol acetate  was  anions  with (44).  q u e n c h i n g the m i x t u r e  acetic  anhydride  To  end  this  t r i p h e n y l methane and until  of enolate  to give a mixture  a solution  of t r i t y l  was  added and  isomerised (14). (15)  of enol acetates  (14)  l i t h i u m , prepared  n - b u t y l l i t h i u m , was  A c e t i c anhydride  (40),  of ketone  added t o k e t o n e  a faint pink colour persisted, indicating  of base.  keto-olefin  q u a n t i t i e s of enol acetates  under a v a r i e t y of m i l d c o n d i t i o n s . Thus i t seemed t h a t t h e b e s t r o u t e by  enol  gave d e s i r e d  o f m i l d a c i d i c c o n d i t i o n s gave no  ( 1 5 ) ] gave a p p r o x i m a t e l y (41)  formation  of  after  a slight f o u r hours  and  from (15) excess the  - 122  -  C14)  r e a c t i o n was  worked  up  t r i p h e n y l methane, was The  isomeric enol  separated their  Enol exposed  to g i v e a crude p r o d u c t from which removed by c r y s t a l l i s a t i o n  acetates  by p r e p a r a t i v e  i r and nmr  C44)  .  (14) and  (44) [ ( 1 4 ) : ( 4 4 ) = 1:6]  their  analysis.  were  g l c and c h a r a c t e r i s e d by a n a l y s i s o f  acetate  (14), d i s s o l v e d i n methylene boron  trifluoride  for five  c h l o r i d e , was minutes.  removal of excess boron t r i f l u o r i d e , evaporation  in  filtration.  spectra.  to gaseous  gave a gum  and  the  of the  w h i c h showed no a b s o r p t i o n b e t w e e n 1700 spectrum,  and  Thus i t w o u l d  gave a c o m p l e x appear  mixture  that enol  and  o f peaks  acetate  After solvent 1800  cm"-*  on g l c  (14) i s n o t  - 123 -  cyclised  t o o(-cuparenone  (13) u n d e r  Lack o f m a t e r i a l p r e c l u d e d c y c l i s a t i o n of enol acetate  these r e a c t i o n c o n d i t i o n s .  f u r t h e r i n v e s t i g a t i o n on  (14).  I t would  the  seem t h a t , i n f u r t h e r  w o r k o f t h i s k i n d i n v o l v i n g s i m i l a r e n o l a c e t a t e s , some method s h o u l d be  found which  selectivity,  gives  the d e s i r e d enol acetate  stereo-  f o r e x a m p l e by r e d u c t i o n o f s u i t a b l e enones o r  c^-chloro-ketones .  CI A n o t h e r method w h i c h  c o u l d p e r h a p s be  o f a s u i t a b l e /3-keto  acid.  tried  i s decarboxylation  - 124 EXPERIMENTAL All  m e l t i n g p o i n t s w e r e d e t e r m i n e d on a K o f l e r b l o c k  uncorrected.'  (-0  Infrared spectra  ) were r e c o r d e d  E l m e r I n f r a c o r d m o d e l 137 s p e c t r o p h o t o m e t e r . resonance s p e c t r a  and r e c o r d e d  on V a r i a n A s s o c i a t e s  Nuclear  magnetic  on a J e o l c o C-60H s p e c t r o m e t e r  spectrometers,  S i g n a l p o s i t i o n s are given  model  i n the T i e r s %  as an i n t e r n a l s t a n d a r d ;  constants  (where a p p r o p r i a t e )  indicated  i n parentheses;  d= d o u b l e t ,  on a P e r k i n -  (*£) w e r e d e t e r m i n e d i n c a r b o n t e t r a c h l o r i d e o r  deuteriochloroform  methylsilane  and a r e  t = triplet,  A-60  o r model  scale, with  T-60.  tetra-  the m u l t i p l i c i t y ,  coupling  and i n t e g r a t e d peak a r e a s a r e  s = s i n g l e t , br.s = broad  singlet,  q = quartet, m = multiplet.  Mass  (M ) were d e t e r m i n e d w i t h  an A E I MS9  +  or  spectrometer.  spectra  Microanalyses  w e r e p e r f o r m e d by Mr. P. B o r d a , M i c r o a n a l y t i c a l L a b o r a t o r y , University  of B r i t i s h  Columbia.  Thin  l a y e r chromatographic ( t i c ) 254  r e s u l t s were o b t a i n e d  using s i l i c a  s o l v e n t A was p e t r o l e u m e t h e r ether  (60-80°C):  (60-80°C);  ethyl acetate  6-Methyl-2-p-tolylhept-5-en-2-ol To magnesium  turnings  equipped,with a dropping inlet,was 0.07  s o l v e n t B was  thickness; petroleum  ( 1 : 1 , v/v) . (17)  (1.7 g, 0.07 m o l e ) i n a 3 - n e c k e d f l a s k  f u n n e l , r e f l u x c o n d e n s e r and n i t r o g e n  reflux,  (80 ml) a t s u c h a r a t e s o as t o m a i n t a i n  a  a f t e r i n i t i a t i o n by g r i n d i n g t h e magnesium.  When t h e r e a c t i o n s u b s i d e d bath  o f 0.5 mm  a d d e d , w i t h m a g n e t i c s t i r r i n g , p _ - b r o m o t o l u e n e ( 1 2 . 1 g,  mole) i n e t h e r  vigorous  g e l HF  t h e f l a s k was h e a t e d on a h o t w a t e r  f o r 0.25 h r t o d r i v e t h e r e a c t i o n t o c o m p l e t i o n .  After  . - 125 cooling  the r e a c t i o n m i x t u r e  en-2-one  (16)  (8.9g,  s l o w l y added and temperature  0.07  -  i n an i c e b a t h ,  mole),  the mixture  dissolved i n ether  then  allowed  o v e r n i g h t , when i t was  The  (20 ml)  g i v e crude  A n a l y s i s by  adding  l a y e r s were  saturated  separated  t i c ( s o l v e n t A) crude  was  o f w h i c h gave 4 , 4 - d i m e t h y l b i p h e n y l 16  (18)  !  (lit.  1105,  cm" ;  805  1  m.p. X  ether  121- 122°C) . "\^ , m  ( C C 1 ) 2.76  F u r t h e r e l u t i o n of the  7.67  831).  g e l column  (40-60°C),  8H),  g,  non-polar  evaporation  solid,  (nujol mull)  v  ( q , J = 8Hz,  4  of a  as a w h i t e  i n vacuo  (12.9  a p p l i e d to a s i l i c a  the column e l u t e d w i t h p e t r o l e u m  122-1240C  (17)  showed t h e p r e s e n c e  product  ether  the e t h e r evaporated  6-methyl-2-p-tolylhept-5-en-2-ol  i m p u r i t y so t h e and  (MgSO^) and  was  a t room  t h e aqueous l a y e r e x t r a c t e d 3 t i m e s w i t h e t h e r , t h e  washed w i t h b r i n e , d r i e d to  to s t i r  w o r k e d up by  aqueous ammonium a c e t a t e s o l u t i o n . and  6-me'thylhept-5-  m.p.  1495,  (s,  6H).  c o l u m n w i t h m e t h a n o l , f o l l o w e d by  e v a p o r a t i o n o f t h e m e t h a n o l , gave p u r e 6-me t h y 1 - 2-p_- t o l y l h e p t - 5 en-2-ol film)  (17)  (10.6  g, 68.5%) as a p a l e y e l l o w o i l . " 0  3 4 2 5 , 2 9 0 5 , 1105,  4.96  (br.s,  8.38  ( , s  I K ) , 7.47  3H),  8.55  815  cm" ; 1  (br.s,  (s,  1H),  (49.6  g,  hydride)  (q, J = 8 H z ,  4  7.70  ( s , 3H),  8.23  (s,  0.23  mole) i n r e d i s t i l l e d  tetrahydrofuran(THF)  (from  (100 ml)  w i t h magnetic s t i r r e r ,  f u n n e l and n i t r o g e n i n l e t , (4.2  g, 0,11  4H),  4H),  (19)  a s o l u t i o n o f 6-methy 1 - 2 - p _ - t o l y l h e p t - 5 - e n - 2 - o l  f l a s k equipped  hydride  ( C C 1 ) 2.87  6H).  6 - M e t h y l - 2 - p _ - t o l y l h e p t a- 2, 5 - d i o l To  T  (liquid  m a x  was  lithium  aluminium  c o n t a i n e d i n a 3-necked reflux  added a s l u r r y  m o l e ) i n THF  (17)  (30 m l ) ,  condenser,  dropping  of sodium  f o l l o w e d by  boroa  solution  - 126 of boron t r i f l u o r i d e added d r o p w i s e .  etherate  The r e a c t i o n m i x t u r e  temperature f o r 2 h r , then solution  ( 2 4 . 7 g, 0.17 m o l e ) i n THF (30 m l ) ,  cooled  was s t i r r e d  a t room  and aqueous 3 M s o d i u m  hydroxide  (130 m l ) . a d d e d , f o l l o w e d by 30% h y d r o g e n p e r o x i d e  (65 m l ) . The r e a c t i o n m i x t u r e  was t h e n  allowed  to s t i r  a further  2 h r a t room t e m p e r a t u r e when t h e l a y e r s w e r e s e p a r a t e d aqueous p h a s e e x t r a c t e d 3 t i m e s  with ether.  solution  and t h e  The c o m b i n e d  organic  l a y e r s w e r e w a s h e d w i t h b r i n e , d r i e d (MgSO^) a n d t h e s o l v e n t evaporated  at reduced pressure  hepta-2,5-diol  t o give crude  ( 1 9 ) ( 5 0 . 4 g, 94%) as a p a l e y e l l o w s y r u p  slowly c r y s t a l l i s e d .  Recrystallisation  80°C) gave p u r e 6 - m e t h y l - 2 - p _ - t o l y l h e p t a - 2 prisms,  m.p.  6-methyl-2-p_-tolyl-  107-109°C. *\}  from p e t r o l e u m  which  e t h e r (60-  , 5 - d i o l ( 1 9 ) as w h i t e  (nujol mull)  3 2 3 5 , 1030 , 930 , 900 ,  IT13.X  870,  825 cm" ; T ( C D C 1 ) 2.78 (m, 4H) 6.75 (m, 1H) , 7.42 ( b r . s , 2 H ) , 1  3  7.67 ( , 3H) , 8.09 (m, 2H)_, 8.47 ( s , 3H) , 8.64 (m, 2H) , 9.16 s  (d,  J = 6Hz, 6H).  Oxidation of 6-methyl-2-p-tolylhepta-2,5-diol  (19)  (a) To 6 - m e t h y l - 2 - p _ - t o l y l h e p t a - 2 , 5 - d i o l  ( 1 9 ) ( 2 . 0 g , 8.5 mmole)  dissolved  i n an i c e b a t h  was  ( 1 . 1 m l ) . The r e a c t i o n m i x t u r e  was  i n acetone  (10 m l ) and c o o l e d 20  added J o n e s ' allowed by  reagent  to s t i r  adding  a t room t e m p e r a t u r e f o r 0.5 h r , t h e n w o r k e d up  w a t e r , s e p a r a t i o n o f t h e l a y e r s and e t h e r e x t r a c t i o n  o f t h e aqueous p h a s e . solvent  (MgSO^) and e v a p o r a t i o n  of the  in v a c u o gave a y e l l o w o i l ( 1 . 7 5 g) w h i c h e x h i b i t e d a  strong i r assigned  Drying  a b s o r p t i o n a t 1775 cm \  and w h i c h was  as 4-methyl-4-p_- t o l y l b u t y r o l a c t o n e ( 2 2 ) .  tentatively  - 127 (b) 6 - M e t h y l - 2 - p _ - t o l y l h e p t a - 2 , 5 - d i o l  ( 1 9 ) ( 1 . 0 g , 4.2 mmole)  was a d d e d t o t h e c o m p l e x f o r m e d b e t w e e n c h r o m i u m  trioxide  24 (0.85  g, 8.5 mmole) and p y r i d i n e ( 8 . 5 m l ) .  mixture  was a l l o w e d  to s t i r  w o r k e d up b y p o u r i n g separated  The r e a c t i o n  a t room t e m p e r a t u r e f o r 6 d a y s and  o n t o b e n z e n e and w a t e r .  The l a y e r s w e r e  a n d t h e aqueous l a y e r e x t r a c t e d w i t h b e n z e n e .  combined o r g a n i c  The  l a y e r s w e r e w a s h e d w i t h b r i n e , d r i e d (MgSO^)  and  the s o l v e n t evaporated  oil  ( 8 9 3 mg) w h i c h was p u r i f i e d b y p r e p a r a t i v e t i c ( s o l v e n t B ) .  Thus c r u d e p r o d u c t heptan-2-ol  at reduced pressure  (60 mg) gave p u r e 5 - k e t o - 6 - m e t h y l - 2 - p _ - t o l y l -  ( 2 1 ) (30 mg, 45% o v e r a l l y i e l d ) . ^0  2 9 1 5 , 1 7 0 0 , 820 c m " ; T  3415,  to give a yellow  .(CDClj)  1  8.48 ( s , 3 H ) , 9.00  (liquid  film)  2.84 (m, 4H) , 7.70 ( s , 3H) ,  ( d , J = 7Hz, 6 H ) .  5 - A c e t o x y - 6 - m e t h y 1 - 2 - p - t o l y 1 - h e p t a n - 2 - o l (24) Acetic  anhydride  ( 4 5 . 0 g, 0.44 m o l e ) was a d d e d t o 6 - m e t h y l -  2-p_-tolylhepta-2,5-diol (200 at  ( 1 9 ) ( 5 0 . 4 g, 0.22 m o l e ) i n p y r i d i n e  m l ) and t h e r e a c t i o n m i x t u r e  room t e m p e r a t u r e .  3 times  was a l l o w e d  to s t i r  overnight  W a t e r was added and t h e p r o d u c t  extracted  w i t h e t h e r , t h e e t h e r was w a s h e d s u c c e s s i v e l y w i t h b r i n e ,  d i l u t e HC1, s a t u r a t e d aqueous s o d i u m b i c a r b o n a t e brine. to  After drying  (MgSO^) t h e e t h e r was e v a p o r a t e d  give 5-acetoxy-6-methyl-2-p_-tolylheptan-2-ol  95%)  s o l u t i o n and  as a p a l e y e l l o w o i l . A)  (liquid  i n vacuo  ( 2 4 ) ( 4 8 . 8 g,  f i l m ) 3510 , 2950 , 1725 ,  HI 3.X  1235,  1 0 1 5 , 820 c m " ; T 1  ( C C 1 ) , 'l.90 4  (m, 4 H ) , 5.36 (m, 1 H ) ,  7.52 ( b r . s , 1 H ) , 7.70 ( s , 3 H ) , 8.06 ( s , 3 H ) , 8.55 ( s , 3 H ) , 9.19  ( d , J = 6.5 H z , 6 H ) .  -  128  Dehydration  of 5-acetoxy-6-methyl-2-p-tolylheptan-2-,ol  (24)  (a) A s o l u t i o n o f 5 - a c e t o x y - 6 - m e t h y l - 2 - p _ - t o l y l h e p t a n - 2 - o l (1.0  g, 3.6 m m o l e ) , o x a l i c  refluxed ether. dried  acid  (1 g) a n d w a t e r  3 times  The e t h e r s o l u t i o n was t h o r o u g h l y w a s h e d w i t h  g i v e a y e l l o w o i l ( 0 . 9 4 g, 1 0 0 % ) . 1725,  (10 m l ) was  f o r 6.5 h r , t h e n w o r k e d up b y e x t r a c t i n g  (MgSO^) a n d t h e e t h e r e v a p o r a t e d  a t reduced  -»  (24)  (liquid  with  brine,  pressure to film)  2950,  1 2 2 5 , 1 0 2 5 , 820 c m " ; T ( C C 1 ) , 2.90 (m, 4 H ) , 4.20 ( t , J = 1  4  6.5 H z , ^ H ) , 4.,82 ( d , J = 1Hz, / H ) , 5.05 ( d , J = 1 H z , / H ) , 1  1  3  3  7.72 ( s , 3 H ) , 8.03 ( s , 2 H ) , 8.07 ( s , 3 H ) , 9.12 (b) 5 - a c e t o x y - 6 - m e t h y l - 2 - p _ - t o l y l h e p t a n - 2 - o l mmole) was d i s s o l v e d  ( t , J = 6Hz, 6 H ) .  ( 2 4 ) ( 0 . 5 g , 1.8  i n p y r i d i n e (5 m l ) and c o o l e d i n a d r y i c e -  acetone  b a t h , under a n i t r o g e n -atmosphere.  thionyl  chloride  mixture  stirred  (0.44g,  Freshly  3.6 mmole) was s l o w l y a d d e d a n d t h e  f o r 0.25 h r , when i t was a l l o w e d t o warm u p .  W a t e r was a d d e d , t h e p r o d u c t  e x t r a c t e d w i t h e t h e r and t h e  e t h e r w a s h e d w i t h b r i n e and d r i e d  (Na^^SO^).  Evaporation o f the  e t h e r i n v a c u o gave a y e l l o w o i l ( 0 . 4 0 g, 851) w h i c h spectral oil  features essentially  prepared  exhibited  i d e n t i c a l w i t h the s p e c t r a of the  i n (a) above.  2-Cyclopropylpropan-2-ol Methyl  distilled  (27)  i o d i d e (186.0 g, 1.31 m o l e ) i n e t h e r  (350 m l ) was  a d d e d t o m a g n e s i u m t u r n i n g s ( 3 5 . 0 g, 1.46 m o l e ) a t s u c h s o as t o m a i n t a i n a v i g o r o u s subsided  reflux.  After  t h e r e a c t i o n m i x t u r e was h e a t e d  f o r 0.5 h r .  On c o o l i n g  a rate  the r e a c t i o n  on a h o t w a t e r  t o 0°C, c y c l o p r o p y l m e t h y l  bath  ketone  (100.0 g , 1.19 m o l e ) i n e t h e r and  the r e a c t i o n mixture  129 ( 3 5 0 m l ) was a d d e d w i t h  stirred  stirring,  a t room t e m p e r a t u r e f o r 2 h r ,  when i t was a g a i n c o o l e d  t o 0°C and s a t u r a t e d aqueous  acetate  The m i x t u r e  s o l u t i o n added.  layers resulted.  They w e r e t h e n  was e x t r a c t e d 3 t i m e s  was s t i r r e d  separated  with ether.  ammonium  until  two c l e a r  and t h e aqueous l a y e r  The c o m b i n e d o r g a n i c  layers  w e r e w a s h e d w i t h b r i n e , d r i e d (MgSO^) a n d t h e e t h e r e v a p o r a t e d i n v a c u o t o g i v e a y e l l o w o i l w h i c h was d i s t i l l e d t o g i v e 2-cyclopropylpropan-2-ol oil,  - ( 2 7 ) ( 8 6 . 5 g , 73%) as a c o l o u r l e s s  b . p . 124-128°-C ( 7 6 0 mm) ( l i t .  2  7  b . p . 121-122°C). \) IIlclX  (liquid  f i l m ) 3 4 0 0 , 3 1 0 0 , 2950, 1 4 6 0 , 1 1 5 0 , 1 0 2 0 , 9 6 0 , 9 2 0 , 8 4 5 ,  825 c m " ; T 1  ( C C 1 ) , 7.66 ( s , 1 H ) , 8 . 8 6 ( s , 6H) , 9.00-9.40 4  (m, 4 H ) , 9.73 ( d , J = 6 H z , 6 H ) . 5-Eromo-2-methylpent-2-ene (28) To 2 - c y c l o p r o p y l p r o p a n - 2 - o l  ( 2 7 ) ( 8 6 . 5 g , 0.865 m o l e ) was  a d d e d , w i t h c o o l i n g a n d s t i r r i n g , 48% H B r (410 m l ) o v e r a p e r i o d o f 0.3 h r .  After stirring  f o r 0.5 h r w i t h c o o l i n g a n d 0.5 h r  a t room t e m p e r a t u r e t h e r e a c t i o n m i x t u r e  was e x t r a c t e d 3 t i m e s  w i t h e t h e r , t h e combined e t h e r e x t r a c t s were washed w i t h s a t u r a t e d aqueous s o d i u m b i c a r b o n a t e  s o l u t i o n , washed  b r i n e , d r i e d (Na2S0 ) and t h e e t h e r e v a p o r a t e d 4  pressure  with  a t reduced  t o g i v e an o i l w h i c h was d i s t i l l e d t o g i v e  methylpent-2-ene  thoroughly  5-bromo-2-  ( 2 8 ) (102.7 g, 72.5%) as a c o l o u r l e s s o i l ,  b.p. 77-82°C (60 mm)  {lit.  2 7  b . p . 84- 85°C {84 mm)]. ^  (liquid IllciX  film)  2960, 2 9 2 5 , 1 6 7 0 , 1 4 4 5 , 1 3 7 5 , 1 2 6 5 , 1 2 0 5 , 1 0 9 5 , 835 c m " ; 1  T(CC1 ) 4  4.33 ( t , J = 7 H z , 1H) , 6.77 ( t , J = 7 H z , 2H) , 7.53  ( t , J = 7Hz, 2 H ) , 8.33 ( d , J = 4 H z , 6 H ) .  - 130 -  2-Methyl-6-p-tolylhex-2-en-6-ol To t h e G r i g n a r d pent-2-e - e i  ,  complex prepared  from 5-bromo-2-methyl-  ( 2 8 ) ( 1 0 . 0 g, 0.06 m o l e ) and magnesium  0.067 mole) i n e t h e r in ether  (29)  (1.6 g,  (50 ml) was added p _ - t o l u a l d e h y d e  ( 7 . 3 p,0.06'mole  (10 m l ) . The r e a c t i o n was a l l o w e d t o s t i r a t room  erature overnight  and t h e n w o r k e d up by a d d i n g  ammonium a c e t a t e s o l u t i o n .  saturated  temp-  aqueous  S e p a r a t i o n o f the l a y e r s , f o l l o w e d by  e t h e r e x t r a c t i o n o f t h e aqueous p h a s e , b r i n e w a s h i n g , d r y i n g (MgSO^) o f t h e e t h e r s o l u t i o n a n d e v a p o r a t i o n ,  i n vacuo, of the  e t h e r gave a y e l l o w o i l (7.9 g, 94%) w h i c h showed glc  (145°C, 3% S e 3 0 ) , one v o l a t i l e p e a k  time  (similar i n retention  t o , b u t n o t i d e n t i c a l w i t h p_-tolualdehyde)  v o l a t i l e peaks.  3 p e a k s on  Separation of the mixture  a n d two l e s s  by p r e p a r a t i v e g l c  (200°C, 30% Se 30) g a v e , i n o r d e r o f d e c r e a s i n g v o l a t i l i t y ,  p-  tolyMethanol  (nujol  ( 3 1 ) , m.p.  57-59°C  (lit.  3  5  m.p.  59°C) . A) ^ ma  ill d - A  m u l l ) 3345, 1515 , 1200 , 1 0 2 5 , 805 cm" ; T ( C D C 1 ) , 1  3  2.76, ( » 5  4H) ,  5.37 ( s , 2 H ) , 7.63 ( s , 3 H ) , 8.11 ( s , 1 H ) ; 6 - k e t o - 2 - m e t h y 1 - 6 - p t o l y l h e x ,-2-ene for  (30), spectral  data i d e n t i c a l  t o t h a t g i v e n below  t h i s compound; and 2 - m e t h y l - 6 - p - t o l y l h e x - 2 - e n - 6 - o l  (liquid  film)  x  1  -2-ene ( 3 0 )  (a) 5 - B r o m o - 2 - m e t h y l p e n t - 2 - e n e (150 m l ) was added t o magnesium so as t o m a i n t a i n , r e a c t i o n slowed  hot water b a t h  m  3345, 2 9 3 5 , 1 4 4 5 , 1 0 6 0 , 815 cm" .  6-Keto-2-methyl-6-p-tolylhex  the  £29). ~\2> ^  (28) (37.6 g, 0.23 m o l e ) i n e t h e r ( 6 . 1 g, 0.25 m o l e ) a t s u c h a r a t e  after initiation,  a vigorous  down t h e f l a s k was h e a t e d  f o r 0.25 h r , t h e n  reflux.  When  t o r e f l u x on a  a s o l u t i o n o f p_-tolualdehyde  - 131 -  (61.0  g, 0.51 m o l e ) i n e t h e r (50 ml) was a d d e d , w i t h . s t i r r i n g ,  a t room t e m p e r a t u r e  and t h e r e a c t i o n m i x t u r e a l l o w e d t o s t i r  o v e r n i g h t a t room t e m p e r a t u r e .  The r e a c t i o n was w o r k e d up by-  a d d i n g s a t u r a t e d aqueous ammonium a c e t a t e s o l u t i o n .  The aqueous  l a y e r was s e p a r a t e d and e x t r a c t e d 3 t i m e s w i t h e t h e r . combined o r g a n i c l a y e r s were washed w i t h b r i n e , d r i e d the e t h e r evaporated w h i c h was d i s t i l l e d  a t reduced  The (MgSO^) and  pressure to give a yellow o i l  to give 6-keto-2-methyl-6-p_-tolylhex  -2-ene  iQ  (30)  ( 2 5 . 6 g, 5 5 % ) , b . p . 103-108°C ( 0 . 2 mm)  (0.1 mm)] w h i c h c r y s t a l l i s e d from p e t r o l e u m  [lit.  on s t a n d i n g .  b . p . 93°C  Recrystallisation  e t h e r (60-80°C) gave an a n a l y t i c a l  sample,  1Q  m.p.  45-46°C ( l i t .  m.p.  47.5-48.5°C). \ )  1 1 7 0 , 9 7 0 , 840 c m " ; T ( C C 1 )  1610,  1  4  m  a  x  ( C C 1 ) 2925 , 1680 , 4  2.19 ( d , J = 4 H z , 2 H ) , 2.81  ( d , J = 4Hz, 2 H ) , 4.87 ( t , J = 3Hz, 1 H ) , 7.13 ( t , J = 3.5 H z , 2 H ) , 7.58 ( , 3 H ) , 7.66 (m, 2 H ) , 8.33 ( s , 6 H ) ; M  +  s  m/e  2 0 2 ; C, 82.86;  H, 8.97; ( c a l c . f o r C H 0 : C, 8 3 . 1 2 ; H, 8 . 9 7 ) . (b) 2 - K e t h y l - 6 - p _ - t o l y l h e x - 2 - e n - 6 - o l ( 2 9 ) (1.0 g , 5.0 m m o l e ) , 20 1 4  acetone  l g  (5 m l ) a n d J o n e s '  reagent  (2 ml) w e r e s t i r r e d  temperature  f o r 0.5 h r when w a t e r was a d d e d .  drying  4  (MgS0 )  Ether  a t room  extraction,  and e v a p o r a t i o n o f t h e e t h e r i n v a c u o gave  6-keto-2-methyl-6-p_-tolylhex  -2-ene ( 3 0 ) i d e n t i c a l  i n a l l respects  t o t h a t p r e p a r e d i n (a) above. 5,5-Dimethyl-2-(4'-methylpent-3'-eny1)-2-p-tolyl-l,3-dioxan  (33)  6-Keto-2-methyl-6-p_- t o l y l h e x -2-ene ( 3 0 ) (62 .7 g, 0.31 m o l e ) , 2 , 2-dimethylpropan-l, 3-diol (1.86  ( 3 2 ) ( 1 5 0 . 7 g, 1.45 m o l e ) , p_-TSA  g) and b e n z e n e (500 ml) w e r e r e f l u x e d f o r 24 h r i n a Dean  and S t a r k t r a p .  On c o o l i n g t h e b e n z e n e was e v a p o r a t e d  a t reduced  - 132 pressure excess  and p e t r o l e u m  ether  (40-60°Cl a d d e d t o p r e c i p i t a t e t h e  d i o l w h i c h was f i l t e r e d  off.  The p e t r o l e u m  was w a s h e d t w i c e w i t h s a t u r a t e d aqueous s o d i u m solution,  then washed t h o r o u g h l y  Removal o f t h e p e t r o l e u m w h i c h was d i s t i l l e d  b . p . 110-112°C  standing. an  (s,  ( 0 . 0 3 mm), w h i c h  - s l o w l y c r y s t a l l i s e d on  from petroleum  62-65°C). * \ )  m a  x  ether  (60-80°C} g a v e  C C C l ^ ) 2975 , 1 1 7 0 ,  ( C C 1 ) 2.81 (m, 4 H ) , 5.00 ( t , J = 4Hz, 1 H ) ,  1  6.67  gave an o i l  ( 3 3 ) ( 5 1 . 0 g , 57%) as a c o l o u r l e s s  s a m p l e , m.p.  820 cm" ; T  1080,  (MgSO^).  1  Recrystallisation  analytical  w i t h b r i n e and d r i e d  5,5-dimethyl-2-(4 -methylpent-3'-  e n y l ) - 2-p_- t o l y l - 1, 3 - d i o x a n oil,  solution  bicarbonate  ether at reduced pressure  to give  ether  4  ( s , 4 H ) , 7.65 ( , 3 H ) , 8.39 ( s , 6 H ) , 8.45 ( s , 3 H ) , 8.76 s  3H) ;  M  +  m/e  288; C, 79.06; H, 9.87; ( c a l c .  f o r C H* 0 : i g  2 8  2  C, 79.12, H, 9 . 7 8 ) . 5,5-Dimethy1-2-(3'-hydroxy-4 -methylpentyl)-2-p-tolyl-1,3-dioxan 1  To (33)  5, 5 - d i m e t h y l - 2- (4 ' - m e t h y l p e n t - 3 ' - e n y l ) - 2 - p _ - t o l y l - l , 3 - d i o x a n  ( 5 1 . 0 g, 0.18 m o l e ) i n THF (100 m l ) was a d d e d , w i t h  sodium b o r o h y d r i d e  ( 3 . 0 2 g, 0.079 m o l e ) i n THF (25 m l ) ,  by b o r o n t r i f l u o r i d e  etherate  The  was a l l o w e d  r e a c t i o n mixture  2 hours then 30%  allowed  Separation  solution  to s t i r  to s t i r  followed  a t room t e m p e r a t u r e f o r solution  (100 m l ) and  (50 m l ) a d d e d and t h e r e a c t i o n  a f u r t h e r 2 h r a t room  temperature,  o f t h e l a y e r s and e t h e r e x t r a c t i o n o f t h e aqueous  l a y e r was f o l l o w e d by b r i n e w a s h i n g and d r y i n g ether  stirring,  (18.9 g, 0.13 m o l e ) i n THF (25 m l ) .  3M aqueous s o d i u m h y d r o x i d e  hydrogen peroxide  mixture  (34)  layer.  Evaporation  (MgS0 ) o f t h e  o f t h e e t h e r i_n v a c u o gave  2-(3' -hydroxy-4 - m e t h y l p e n t y l ) - 2 - p _ - t o l y l - 1 , 3 - d i o x a n 1  4  5,5-dimethyl-  (34) (53.3 g,  - 133 -  96.6%)  as a c o l o u r l e s s , v i s c o u s o i l . " \ ) (liquid ' max  film) '  n  J  2 9 2 5 , 1 1 7 0 , 1 0 7 5 , 820 c m " ; T ( C C 1 ) 2.82 (m, 4 H ) , 6.64 1  4  3400, ' ( s , 4H),  7.63 ( s , 3 H ) , 8.73 ( s , 3 H ) , 9.13 ( d , J = 5Hz, 6 H ) , 9.41 ( s , 3 H ) . 5,5-Dimethyl-2-(5'-acetoxy-4  ' - m e t h y l p e n t y 1 ) - 2 - p - t o l y l - l , 3 - d i o x a n (35)  5 , 5 - D i m e t h y 1 - 2 - ( 3 '-hydroxy-4'-methylpentyl)-2-£-tolyl-l,3dioxan  ( 3 4 ) ( 2 4 . 0 g, 0.079  0.157 m o l e ) and p y r i d i n e  mole), a c e t i c anhydride  (50 ml) w e r e s t i r r e d  o v e r n i g h t a t room  t e m p e r a t u r e , when w a t e r was a d d e d and t h e r e a c t i o n extracted  three times w i t h ether.  mixture  The e t h e r s o l u t i o n was  t h o r o u g h l y washed w i t h b r i n e , d r i e d evaporated  ( 1 5 . 9 5 g,  ( M g S 0 ) and t h e e t h e r 4  a t reduced pressure t o give  5,5-dimethyl-2-(3'-acetoxy-  4'-methylpentyl)-p_-tolyl-l,3-dioxan  ( 3 5 ) ( 2 6 . 9 g , 98.5%) as a  colourless o i l . ^  2940, 1730, 1465, 1360,  (liquid  film)  nicix  1235, 1170 , 1 0 7 5 , 1015 , 970 , 920 , 820 c m " ; T ( C C l ) 2.88 Cm, 4H) , 1  4  5.39  (br.s,  1 H ) , 6.69 ( s , 4 H ) , 7.64 ( s , 3 H ) , 8.07 ( s , 3 H )  ("s, 3H) , 9.17 ( d , J = 6Hz, 6H) , 9.44  ( s , 3H) ; M  +  ;  8.78  m/e 3 4 8 .  4- A c e t o x y - 5 - m e t h y l - 1 - p - t o l y l h e x a n - 1 - one ( 3 6 ) 5,5 - D i m e t h y l - 2 - ( 3 ' - a c e t o x y - 4 '- methylpentyl)-2-£-tolyl-1,3dioxan HC1  ( 3 5 ) ( 2 5 . 0 g, 0.072 m o l e ) , a c e t o n e  (10 ml) were s t i r r e d  o v e r n i g h t a t room t e m p e r a t u r e .  b i c a r b o n a t e was a d d e d u n t i l ( l i t m u s ) and t h e a c e t o n e ether by  (300 m l ) a n d 6N .  t h e r e a c t i o n m i x t u r e was  then evaporated  i n vacuo.  Sodium  neutral Petroleum  (40-40°C) was a d d e d a n d t h e s o d i u m b i c a r b o n a t e removed  filtration.  brine, dried  The p e t r o l e u m e t h e r s o l u t i o n was w a s h e d w i t h  (MgSO^) and t h e s o l v e n t e v a p o r a t e d  w h i c h was d i s t i l l e d t o g i v e  t o g i v e an o i l  4-acetoxy-5-methyl-l-£-tolylhexan-l-one  - 134 ( 8 . 7 8 g, 46%) a s a c o l o u r l e s s o i l , b . p . 125-128°C CO.4 mm).  (36) v>  (liquid  ^(CC1 X 4  f i l m ) 2 9 8 5 , 1 7 3 0 , 1 6 8 0 , 1 6 0 5 , 1 2 3 5 , 1 0 2 0 , 820 c m " ; 1  2.18 ( d , J = 8Hz, 2H) , 2.78 ( d , J = 8 H z , 2H) , 5.25 (m, 1H) ,  7.14 ( t , J = 6.5 H z , 2 H ) , 7.57 ( s , 3 H ) , 8.01 ( s , 3 H ) , 9.04 ( d , J = 7Hz,  6 H ) ; M+ m/e 262 ; C, 7 2 . 9 3 ; H, 8.53; ( c a l c .  for C  1 6  H  2 2  0 : 3  C, 73,26; H, 8 . 4 6 ) . 5 - A c e t o x y - 6 - m e t h y 1 - 2-p- t o l y h e p t -1 - ene ( 2 5 ) Sodium h y d r i d e  (50%..  o i l dispersion)  was w a s h e d w i t h d r y e t h e r , sulphoxide  (DMSO)  nitrogen until mixture  ( 1 . 3 g, 0.027 m o l e )  d r i e d in v a c u o , added t o d i m e t h y l -  (20 m l ) , a n d t h e m i x t u r e  heated a f V 8 0 ° C  e v o l u t i o n o f n i t r o g e n ceased  was c o o l e d  i n an i c e / w a t e r  phosphonium bromide  bath  {y0 . 5 h r ) .  under  The  and m e t h y l t r i p h e n y l  ( 9 . 7 g, 0.0 27 m o l e ) , d i s s o l v e d I n DMSO (40 m l )  added w i t h s t i r r i n g ,  t o g i v e a deep y e l l o w  s o l u t i o n was a l l o w e d  t o warm t o room t e m p e r a t u r e a n d 4 - a c e t o x y - 5 -  methyl-l-p_-tolylhexan-l-one (10 m l ) added d r o p w i s e . the  r e a c t i o n mixture  (40-60°C).  solutionTKe  (36) ( 7 . 1 2 g, 0,027 m o l e ) i n DMSO  Stirring  was c o n t i n u e d  was e x t r a c t e d 4 t i m e s  The p e t r o l e u m e t h e r  overnight,  with petroleum  s o l u t i o n was t h e n w a s h e d  DMSO, w a s h e d w i t h b r i n e , d r i e d (MgSO^) a n d t h e s o l v e n t at reduced pressure  1735,  ( 2 5 ) ( 2 . 0 g, 28.5%) as a  o i l , b . p . 96-10S°C ( 0 . 0 4 mm) ."O  _  1370, 1 2 3 5 , 1 0 2 5 , 8 9 0 , 825 c m " ; T ( C C l )  M  = 6Hz,lH), +  m/e 2 6 0 .  with  evaporated  1  4  (liquid  f i l m ) 2960 ,  2.87 (m, 4 H ) ,  4.83 ( d , J = 1.5 H z , 1 H ) , 5.0 5 ( d , J = 1.5 H z , 1 H ) , 5.29 J  ether  t o g i v e a n o i l w h i c h was d i s t i l l e d t o g i v e  5 - a c e t o x y - 6 - m e t h y 1 - 2-p_- t o l y l h e p t - 1 - ene colourless  then  (q,  7.65 ( , 3 H ) , 7.98 ( , 3 H ) , 9.14 ( d , J = 7Hz, 6 H ) ; s  s  - 135 -  5- H y d r o x y - 6 - m e t h y l - 2 - p - t o l y l h e p t - l - e n e (37) 5-Acetoxy-6-methyl-2-£-tolylhept-l-ene sodium h y d r o x i d e allowed to reflux  (4.0 g ) , m e t h a n o l for 4 hr.  times w i t h petroleum  ether  was w a s h e d w i t h b r i n e ,  ( 2 5 ) ( 2 . 0 g , 7.7 mmole)  (30 m l ) and w a t e r  The r e a c t i o n m i x t u r e was e x t r a c t e d 3  (40-60°C) , t h e p e t r o l e u m  dried  CMgSOp  ether  as a c o l o u r l e s s  m  a  x  (liquid  film)  ( 3 7 ) (1.34 g ,  3380, 2925, 1630,  1 4 5 5 , 1 3 7 0 , 1 0 4 5 , 8 9 0 , 8 2 5 , 735 cm" ; "C CCC1 ) 2.88 (m, 4 H ) ,  1510,  1  4.81 (d,  o i l . "0  solution  and t h e s o l v e n t removed i n  v a c u o t o g i v e 5-hydroxy-6-methyl-2-£-tolylhept-l-ene 80%)  (5 m l ) w e r e  (m, 1 H ) , 5.00 (m, 1 H ) , 6.68  (m, 1 H ) , 7.66 ( s , 3 H ) , 9.15  J = 6Hz, 6 H ) .  6- Me t h y 1 - 2 - p - t o l y l h e p t - 1 - e n - 5 - o n e To  (15)  5-hydroxy-6-methyl-2-p_-tolylhept-l-ene  mmole) i n a c e t o n e ( 1 0  ( 3 7 ) ( 1 . 3 4 g , 6.15  m l ) was a d d e d , w i t h s t i r r i n g  and c o o l i n g ,  20 Jones' for  reagent  (2 m l ) .  The r e a c t i o n m i x t u r e was a l l o w e d t o s t i r  0.5 h r t h e n w o r k e d up b y a d d i n g w a t e r .  The a q u e o u s  layer  was e x t r a c t e d 3 t i m e s w i t h e t h e r , t h e e t h e r w a s h e d w i t h b r i n e , dried  (MgS0 ) and t h e e t h e r e v a p o r a t e d 4  an o i l w h i c h was d i s t i l l e d (15) •"O  to give  ( 1 . 0 0 g, 75%) as a c o l o u r l e s s  mav  . (liquid  film)  at reduced  pressure to give  6-methyl-2-£-tolylhept-l-en-5-one o i l , b . p . 86-88°C  ( 0 . 0 4 mm).  2 9 8 5 , 1710 , 1 5 1 5 , 1 4 6 5 , 1070 , 8 9 5 , 825 c m " ; 1  ill cA-A.  t(CCl ), 4  Hz,  2.84 (m, 4 H ) , 4.83 ( d , J = 1.5 H z , 1 H ) , 5.03 ( d , J = 1.5  1 H ) , 7.64 ( s , 3 H ) , 8.97 ( d , J = 8Hz, 6 H ) ; M  2-Methylheptan-3-ol n - B u t y l bromide  +  m/e 216.  (59) ( 3 0 . 1 g, 0.22 m o l e ) d i s s o l v e d  i n ether  (100 m l ) was a d d e d t o magnesium t u r n i n g s (4.8 g , 0.24 m o l e ) c o n t a i n e d i n a 3-necked f l a s k e q u i p p e d reflux  condenser  and n i t r o g e n i n l e t .  w i t h a magnetic  stirrer,  A d d i t i o n was r e g u l a t e d s o as  - 136 -  to maintain a vigorous r e f l u x .  When t h e a d d i t i o n was c o m p l e t e d t h e  r e a c t i o n m i x t u r e was t h e n a l l o w e d t o s t i r temperature until  when t h e r e a c t i o n was w o r k e d up b y c a r e f u l l y  e f f e r v e s c e n c e ceased.  dissolve  f o r 2 h r a t room adding  water  S u f f i c i e n t 6N HC1 was t h e n a d d e d t o  t h e e m u l s i o n formed  by i n o r g a n i c s a l t s .  The two l a y e r s  w e r e s e p a r a t e d a n d t h e aqueous l a y e r e x t r a c t e d 3 t i m e s w i t h e t h e r , the e t h e r washed t h o r o u g h l y w i t h b r i n e , d r i e d ether evaporated 821) 990  CMgSO^) and t h e  i n vacuo t o g i v e 2-methylheptan-3-ol  as a c o l o u r l e s s  oil.\)  o v  (liquid  film),  ( 3 9 ) (21.4 g,  3390 , 2940 , 1460 ,  c m " ; f C C C l ^ , 6.73 ( b r . s , 1H) , 7.57 (s , 1H) , 8.33-8.83 Cm, 7H) , 1  9.12  ( d , J = 7Hz, 9H).  2-Methylheptan-3-one (38) To acetone  2-methylheptan-3-ol  ( 3 9 ) ( 2 1 . 4 g, 0.165 m o l e ) d i s s o l v e d i n  (25 m l ) was a d d e d , w i t h c o o l i n g a n d s t i r r i n g ,  reagent^  (35 m l ) .  temperature  The m i x t u r e was a l l o w e d t o s t i r  f o r 4 h r t h e n w o r k e d up b y a d d i n g w a t e r  t h e aqueous l a y e r 3 t i m e s w i t h e t h e r . washed w i t h b r i n e , d r i e d  ( 1 4 . 3 g, 68%) as a c o l o u r l e s s  ^max  (liquid  film)  a t room and e x t r a c t i n g  The e t h e r s o l u t i o n was  (MgSO^) a n d t h e e t h e r e v a p o r a t e d  t o g i v e an o i l w h i c h was d i s t i l l e d (38)  Jones'  to give oil,  i n vacuo  2-methylheptan-3-one  b.p.82-84°C (64 mm),  2975, 1 7 1 0 , 1 4 6 0 , 1 3 7 5 , 1 3 6 0 , 1045 c m " ; T ( C C 1 ) 1  4  7.23-7.80 (m, 3H) , 8.30-8.83 (m, 4 H ) , 9.00 ( t , J = 7 H z , 9 H ) . Camphor e n o l a c e t a t e ( 4 2 ) n-Butyl lithium was  (10 m l o f 2.1 M h e x a n e s o l u t i o n , 0.02 m o l e )  a d d e d t o camphor (4) ( 3 . 0 4 g, 0.02 m o l e ) d i s s o l v e d i n t e t r a -  hydrofuran  (20 m l ) .  a c e t i c anhydride  The r e a c t i o n m i x t u r e was c o o l e d t o -78°C,  ( 4 . 4 8 g , 0.04 m o l e ) was a d d e d a n d t h e m i x t u r e  - 137 allowed  to s t i r  a t room t e m p e r a t u r e f o r 2.5 h r .  and t h e aqueous thoroughly ether glc  l a y e r e x t r a c t e d 3 times w i t h ether,  w i t h b r i n e , and d r i e d ( M g S 0 ) .  i n vacuo  gave  washed  of the  a r e d o i l w h i c h was p u r i f i e d by p r e p a r a t i v e  30% Se 30) t o g i v e p u r e camphor e n o l  Q  added  the ether  Evaporation  4  (200 C,  W a t e r was  a c o l o u r l e s s o i l . -\}  (liquid  f i l m ) 2940,  acetate  [ 4 2 ) as  1760, 1360, 1205,  IIlclX  1120,  1005 c m " ; ^ ( C C l )  4.48  1  4  1 H ) , 7.90  ( , 3 H ) , 9.06 s  ( d , J = 4Hz, 1H) , 7.68 [ t , J = 3Hz,  ( s , 6 H ) , 9.24  ( s , 3H).  .Enol a c e t y l a t i o n o f 2 - m e t h y l h e p t a n - 5 - o n e (a)  2-Methylheptan-3-one  acetate  (38)  ( 3 8 ) (64 mg, 0.5 m m o l e ) , camphor  ( 4 2 ) (150 g, 0.77 mmole) and o x a l i c  refluxed overnight  i n benzene  and t h e b e n z e n e  removed  a c i d [5 mg) w e r e  (2 m l ) . The b e n z e n e  washed w i t h s a t u r a t e d sodium b i c a r b o n a t e  solution,  at reduced pressure.  (b) The above as c a t a l y s t ,  an e s s e n t i a l l y  (c) 2 - M e t h y l h e p t a n - 3 - o n e for  d r i e d CMgSO^)  the presence of the  and camphor. ( 4 ) .  e x p e r i m e n t was r e p e a t e d ,  to give  s o l u t i o n was  A n a l y s i s of the  p r o d u c t b y g l c (100°C, 3% Se 30) i n d i c a t e d o n l y two s t a r t i n g m a t e r i a l s  u s i n g p_-TSA.  similar  (10 mg)  result.  ( 3 8 ) [15 mg, 0.12 mmole) was  stirred 32  6 minutes i n p e r c h l o r i c a c i d / a c e t i c anhydride reagent  ml).  The r e a c t i o n m i x t u r e  aqueous acetate.  sodium b i c a r b o n a t e After drying  enol  was t h e n n e u t r a l i s e d w i t h  CI•5  saturated  s o l u t i o n and e x t r a c t e d w i t h  ethyl  (MgSO^) t h e e t h y l a c e t a t e was removed i n  v a c u o a n d t h e c r u d e " p r o d u c t i d e n t i f i e d by g l c (100°C, 3% Se 30) as 2 - m e t h y l h e p t a n - 3 - o n e [ 3 8 ) . (d)  2-Methylheptan-3-one  acetate  C38) Cl•0 g> 7.8 m m o l e ) ,  ( 3 7 ) (20 m l ) a n d o x a l i c  n i g h t a t 110°C, g i v i n g a v e r y  isopropenyl  a c i d (250 mg) w e r e h e a t e d  slow rate of d i s t i l l a t i o n .  overEther  - 138  -  was  a d d e d t o t h e d i s t i l l a t i o n r e s i d u e and  was  dried  give  (MgSO^) and  the ether evaporated  an o i l w h i c h was  recovered (e)  shown by  2-Methylheptan-3-one (37)  (giving  a very  at reduced  pressure  g l c a n a l y s i s (100°C, 3%  (20 ml)  C38)  (1•0  and p_-TSA (200  slow  g,  7.8  mg)  Se  to  30)  to  be  mmole), i s o p r o p e n y l  were h e a t e d  r a t e of d i s t i l l a t i o n )  w i t h more i s o p r o p e n y l a c e t a t e  solution.  e v a p o r a t i o n of the e t h e r at reduced  pressure  was  shown by  30)  g l c a n a l y s i s (100°C, 31 Se  starting material.  ( i n order of decreasing v o l a t i l i t y ) (liquid in  1205 , 1045  cm" ; 1  1H),  7.91  2H),  8.97  ( d , J = 7Hz,  (43)  ( 3 3 . 6 % ) . A)  (s,  trans -  film)  gave an o i l w h i c h 3  Separation Se  30)  of  gave  3-acetoxy-2-methylhept-  2940, 1750,  1460 ,  1355,  3.x  ^ ( C C l ^ , 5.10  6Hz,  added  (MgSO^)  to c o n s i s t of  3 compounds by p r e p a r a t i v e g l c (160°C, 30%  (34.8%).  up  E t h e r was  Drying  and  3-ene (40)  110°C  the e t h e r s o l u t i o n washed w i t h  s a t u r a t e d aqueous s o d i u m b i c a r b o n a t e  p r o d u c t s , none o f w h i c h was  at  f o r 48 h r t o p p i n g  (37) when r e q u i r e d .  t h e d i s t i l l a t i o n r e s i d u e and  these  solution  starting material.  acetate  to  the e t h e r  3H),  8.24 9H);  (liquid  ( t , J = 6Hz, ( t , J = 6Hz,  1H) , 7.65  2H),  8.65  (t, J = (q, J  6Hz,  =  c i s - 3-acetoxy-2-methylhapt-3-ene film)  2975, 1760,  1365,  1210,  1180  (m,  1H) ,  in 3.x  1155,  1035  7.94 ene  cm" ; 1  ( s , 3H), (41)  r  Tj(CCl ), 4  9.03  5.13  ( d , J = 7Hz,  ( 3 1 . 7 % ) ,"\)  (liquid  ( t , J= 9H); film)  8Hz, and  1H) , 7.24  3-acetoxy-2-methylhept-2-  2925, 1755 , 1360 , 1205 ,  1135,  IU3X  1060  cm" ;  9.10  (m,  (f)  1  To  ^ 3H).  (CC1 ),  7.95  4  ( s , 3H),  8.31  ( s , 3H),  8.52  (s,  3H),  g,  0.01  .  a s o l u t i o n of 2-methylheptan-3-one  mmole) i n t e t r a h y d r o f u r a n (10 ml)  was  (38)  (1.28  added, w i t h s t i r r i n g  and  - 139 cooling  (ice/water), sufficient  from t r i p h e n y l methane  (4.88  trityl  lithium  s o l u t i o n [prepared  n.02 m o l e ) and n - b u t y l  g >  lithium  (10 ml o f 2.1 M h e x a n e s o l u t i o n ) ] t o - g i v e  a persistent pink  The  a c e t i c a n h y d r i d e (2.04 g ,  s o l u t i o n was t h e n c o o l e d  (ice/water),  0.02 m o l e ) a d d e d , and t h e m i x t u r e a l l o w e d t o s t i r temperature f o r 4 h r .  a t room  W a t e r was a d d e d a n d t h e p r o d u c t e x t r a c t e d  3 t i m e s w i t h e t h e r w h i c h was t h e n w a s h e d t h o r o u g h l y w i t h aqueous sodium b i c a r b o n a t e s o l u t i o n . e t h e r was e v a p o r a t e d t o g i v e (10 mm  characteristics  methylhept-3-ene  After drying  saturated  (MgSO^) t h e  an o i l , w h i c h was d i s t i l l e d  . g) t o g i v e a c o l o u r l e s s  spectral  colour  a t 65°C  o i l (400 mg, 23.5%) w h i c h  almost i d e n t i c a l  exhibited  to trans-3-acetoxy-2-  ( 4 0 ) p r e p a r e d as i n ( e ) a b o v e .  A n a l y s i s by g l c  (100°C, 3% Se 30) showed t h e m i x t u r e c o n s i s t e d o f t r a n s - 3 - a c e t o x y 2-methyl-hept-3-ene (41)  ( 4 0 ) ( 9 0 % ) and  3-acetoxy-2-methylhept-2-ene  (10%).  A t t e m p t e d i s o m e r i s a t i o n s o f t r a n s - 5 - a c e t o x y - 2 - m e t h y l h e p t - 3 - e n e (40) (a) T r a n s - 3 - a c e t o x y - 2 - m e t h y l h e p t - 3 - e n e acetate  ( 0 . 7 5 m l ) was s t i r r e d  with perchloric the e t h y l  acid/acetic  ( 4 0 ) (15 mg), i n e t h y l  a t room t e m p e r a t u r e f o r 7 m i n u t e s  anhydride reagent.""  After  washing  a c e t a t e s o l u t i o n w i t h s a t u r a t e d sodium b i c a r b o n a t e s o l u t i o n  and e v a p o r a t i n g  the ether, g l c a n a l y s i s  (100°C, 3% Se 30) i n d i c a t e d  the p r e s e n c e o f o n l y t r a n s - 3-acetoxy-2-methylhept-3-ene. (b) T r a n s - 3 - a c e t o x y - 2 - m e t h y l h e p t - 3 - e n e  ( 4 0 ) (15 mg), c y c l o h e x a n e  36 (1.5 m l ) and i o d i n e  (1 c r y s t a l ) w e r e s t i r r e d  On e v a p o r a t i o n o f t h e c y c l o h e x a n e g l c a n a l y s i s indicated (40).  a t 90°C f o r 24 h r . (100°C, 3% Se 30)  the presence of only trans - 3-acetoxy-2-methylhept-3-ene  - 140 -  ( c ) T r a n s - 3 - a c e t o x y - 2-meth.ylh.ept-3-ene acetate hr.  (2 m l ) a n d p_-TS. A  [10 mg) w e r e h e a t e d a t 90°C f o r 24  E t h e r was a d d e d , t h e e t h e r  aqueous sodium b i c a r b o n a t e vacuo t o g i v e  a product  2-methylheptan-3-one  C4Q) (50 mg) , i s o p r o p e n y l  s o l u t i o n washed w i t h  s o l u t i o n and t h e e t h e r  saturated  evaporated i n  w h i c h g l c a n a l y s i s showed t o be  (38) and a l i t t l e  mainly  t r a n s - 3-acetoxy-2-methy1-  hept-3-ene ( 4 0 ) . Enol A c e t y l a t i o n of 6-methyl-2-p-tolylhept-l-en-5-one To  a solution  0  f 6-methyl-2-p_-tolylhept-l-en-5-one  g, 4.63 mmole) i n d r y t e t r a h y d r o f u r a n trityl  lithium  s o l u t i o n , prepared  10 mmole) i n t e t r a h y d r o f u r a n o f 2.34 M h e x a n e s o l u t i o n , pink  colour.  (15 m l ) a n d n - b u t y l  lithium  g,  (4.28 ml  10 mmole) t o g i v e a p e r s i s t e n t f a i n t i n ice, acetic allowed  anhydride  t o s t i r a t room  W a t e r was t h e n a d d e d , t h e l a y e r s  t h e aqueous phase e x t r a c t e d 3 times  organic  sufficient  f r o m t r i p h e n y l methane [2.44  The s o l u t i o n was t h e n c o o l e d  temperature f o r 4 h r .  (15) (1.0  (10 m l ) was a d d e d  ( 0 . 9 4 5 g , 9.26 mmole) a d d e d a n d t h e m i x t u r e  and  (15)  with ether.  separated  The c o m b i n e d  l a y e r s w e r e d r i e d (MgSO^) and t h e s o l v e n t e v a p o r a t e d i n  vacuo t o give  a yellow  oil.  A little  petroleum ether  (60-80°C)  was a d d e d and t h e s o l u t i o n s t o r e d o v e r n i g h t  a t 0°C t o p r e c i p i t a t e  t r i p h e n y l m e t h a n e , w h i c h was f i l t e r e d  off.  A f t e r evaporation  the  solvent the mixture  b y p r e p a r a t i v e g l c (250°C,  30%  Se 30) t o g i v e  was s e p a r a t e d  i n order  of decreasing  volatility,  6-methyl-2-£-tolylhepta-l,4-diene [ 4 4 ) ( 4 7 . 3 mg), X}  m  film)  2960 , 1 7 5 0 , 1200 , 8 9 5 , 825 c m " ; ^ ( C C l ) 1  4  a  of  5-acetoxyx  (liquid  2.85 [ q , J = 7Hz,  4H) , 4.73 ( b r . s , 1 H ) , 5.00 ( b r . s , 1 H ) , 5.03 ( t , J = 7Hz, 1 H ) ,  - 141  Cd,  7.00 (d,  J  diene  J =.  7Hz,  2H},  = 7Hz,: 6H) ; and  7.67  Cs,  3H) , 7.88  3H),  9.03  5 - a c e t o x y - 6 - m e t h y l - 2 - p _ - t o l y l h e p t a - l ,5-  (7.9 mg) , A)  (14)  Cs,  -  (liquid  film),  2 9 6 0 , 1755,  1200,  900,  max 820 7.65  T  cm" ; 1  ( C C 1 ) 2.87  (m,  4  ( s , 3H),  7.92  (s,  4H) , 4.83  (br.s,  1H) , 5.00  ( b r . s , 1H) ,  3H).  Treatment of 5 - a c e t o x y - 6 - m e t h y l - 2 - p - t o l y l h e p t a - l , 5 - d i e n e w i t h boron  trifluoride  Gaseous b o r o n t r i f l u o r i d e  was  passed  through  5-acetoxy-6-methyl-2-p_-tolylhepta-1, 5-diene methylene c h l o r i d e was  (25 ml)  f o r 5 minutes.  r e m o v e d by p a s s i n g a s t r e a m  s o l u t i o n f o r 0.25 was  (14)  (7.9 mg)  Excess  boron  o f n i t r o g e n gas  h r , a f t e r which  a solution  through  washed w i t h b r i n e , d r i e d  the  (175°C, 31 Se  and 30)  1800 t o be  cm  1  in trifluoride  solution  solution,  solvent evaporated  pressure to give a y e l l o w o i l which  a b s o r p t i o n b e t w e e n 1700 analysis  (MgSO^) and  and was  e x h i b i t e d no shown by  a complex m i x t u r e  of  the  the methylene c h l o r i d e  washed w i t h s a t u r a t e d aqueous sodium b i c a r b o n a t e  reduced  (14)  at  infrared  glc  o f compounds.  - 142 BIBLIOGRAPHY  1.  J . N. 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"Handbook o f C h e m i s t r y and P h y s i c s " , 4 9 t h E d . R u b b e r Company, C l e v e l a n d , 1 9 6 8 , p.C-410.  and V. K r a m a r , J . O r g . Chem., 1 9 6 3 , _28, 3362. and P. N. R a o , J . O r g . Chem., 1 9 6 6 , 31_,  324.  a n d E. W. W a r n h o f f , T e t r a h e d r o n  The C h e m i c a l  PART I I I  PHOTOCHEMICAL CLEAVAGE OF PYRONES  - 14.4 INTRODUCTION 1 2 C o l l i e was t h e f i r s t  to suggest  compounds c o u l d be b i o s y n t h e s i s e d l i n e a r poly-|fi-diketone c h a i n , compounds d e r i v e d between adjacent  '  aromatic  f r o m a c e t i c a c i d b y way o f a  a characteristic  i n t h i s manner b e i n g hydroxyl  t h a t some  or carbonyl  feature of  a 1,3-relationship groups.  Collie  t h a t t h e s t a r t i n g u n i t was a c e t i c a c i d and t h a t t h i s with  f u r t h e r molecules of a c e t i c acid to give  diketone  chain which could  condensations Not but  to give  compounds  .  first  postulate  OH  Thus he c o n v e r t e d  He a l s o o b t a i n e d  type syntheses o f  dehydroacetic  acid (1),  (2) b y t r e a t m e n t  orcinol  theory  [2) by a c i d  with catalysed  0  CD  (2)  c y c l i s a t i o n of hepta-2,4,6-trione from dehydroacetic  or Claisen  the polyacetate  biogenetic  a protected ^5-triketone, into orcinol sodium h y d r o x i d e .  t h e l i n e a r poly-y£-  compounds.  he a l s o p e r f o r m e d t h e f i r s t  aromatic  condensed  then undergo i n t e r n a l a l d o l  aromatic  only d i d C o l l i e  envisaged  acid (1).  (3) w h i c h i t s e l f was  obtained  - 145 -  (3)  (2)  The p o l y a c e t a t e t h e o r y was " r e d i s c o v e r e d " a n d e l a b o r a t e d by B i r c h ^  and R o b i n s o n . 5  Since  then v a r i o u s m o d i f i c a t i o n s have  b e e n made, s u c h as t h e i m p o r t a n c e chain propagating acid as  unit  of malonyl  co-enzyme  and t h e u s e o f a c i d s o t h e r  as t h e c h a i n s t a r t e r u n i t .  the acy1-polymalonate route  The t h e o r y to aromatic  i s now  than  A as t h e acetic  considered  compounds t o t a k e  i n t o a c c o u n t t h e s e more r e c e n t l y e l u c i d a t e d f e a t u r e s , a n d i s briefly  summarised i n F i g u r e  include  alkylations,  I.  The s e c o n d a r y m o d i f i c a t i o n s  o x i d a t i o n s , r e d u c t i o n s , h a l o g e n a t i o n and  introduction of nitrogen. In recent years the  conversion  unprotected,  t h e r e h a v e b e e n numerous  of poly-j3-diketone  to aromatic  poly-^-diketone  of aromatic  chains, either protected or  compounds.  One way o f p r o t e c t i n g t h e  c h a i n i s as a p y r o n e a n d t h i s  b y t h e r e s e a r c h g r o u p a t U.B.C.  reports describing  has been  The b i o g e n e t i c t y p e  compounds f r o m p o l y - / 5 - d i k e t . o n e  used  synthesis  c h a i n s has r e c e n t l y  - 146 -  CH COSCoA 3  Fatty  acids  Propionate  Biotin/ATP/Mg  ++  /HC0  3  V CH C0SCoA o  I  2  C0 H 2  Enzyme  V  CH 2"C0S-Enzyme  RCOSCoA  C0 H 2  chain starter  chain propagating  unit  unit  A Cinnamic acids Benzoic acids Nicotinic acid Anthranilic acid  RCOCH COSEnzyme 2  A Shikimate  chain unit  Pathway  propagating  RCO(CH CO) CH COSEnzyme ( n = 1-8) 2  2  intramolecular c o n d e n s a t i o n s and secondary modifications P h e n o l i c compounds Figure  I:  Acy1-polymalonate route  to aromatic  compounds  - 147  -  b e e n r e v i e w e d by Money . As riate  an e x a m p l e , b i s p y r o n e  conditions,  (4)  can  to o r s e l l i n i c a c i d  be  c o n v e r t e d , under  (5)  (and  7 and  carbomethyoxyphloracetophenone  derivatives  (6).  gave n a t u r a l l y o c c u r r i n g  thereof)  8  Other bispyrone 7a p h e n o l i c compounds and  (6) trispyrone  derivatives  approp-  '  (5)  (7)  a l s o gave compounds o f n a t u r a l t y p e when t r e a t e d 7 under a p p r o p r i a t e c o n d i t i o n s . T e t r a p r y o n e (8) has a l s o b e e n 7 prepared b u t c o u l d n o t be c o n v e r t e d t o a r o m a t i c compounds. Thus an a l t e r n a t i v e method o f j o i n i n g t h e p y r o n e r i n g s 9 was  devised  by  D o u g l a s and  Money.  This  method g i v e s  rise  to  p y r o n e u n i t s which, a r e structures, synthesis  linear and  148  -  rather  reactions  t h a n c o n d e n s e d , .and of t h i s  type of  the  compound,  q e.g.  pyrone  ( 9 ) , have been f u l l y  I t was  subsequently found that  type,  e.g.  d i d not  pyrone  lead  to the  t r e a t m e n t of the conditions pyrone and  (9)  (10)  described.  t r e a t m e n t o f compounds o f  u n d e r a v a r i e t y o f b a s i c and  formation  acid  o f a r o m a t i c compounds.  corresponding methyl ether  gave e v e r n i n i c a c i d ( 1 2 ) . ^  (11)  conditions  However  under  basic  Attempts to convert  t o a r o m a t i c compounds w e r e o n l y p a r t i a l l y  alternative ring cleavage-aromatisation  this  linear  successful  conditions  were  - 149 investigated. to^-polyketo be  In particular esters  photochemical conversion  (and hence t o a r o m a t i c  o f 0<-pyrones  compounds) seemed t o  a possibility.  0  OMe  OMe  0 MeO  .  0 ^ 0  0  co a 2  CO  C0 Me  C0 Me  2  2  (12)  (11) Previous e*-pyrone  s t u d i e s b y de Mayo  (13) p h o t o l y s e s  p-acetonylcrotonate  (14).  11  h a v e shown t h a t  4,6-dimethyl  i n methanol s o l u t i o n to give De Mayo e x p l a i n e d  this  methyl  r e a c t i o n by  h-o  Me OH - o  o  -0  (13) invoking the intermediacy  2  (14) of ketene  h a v e s u g g e s t e d t h a t (3 - l a c t o n e  (IS)  C0 Me  ( 1 5 ) b u t C o r e y and  ( 1 6 ) may be i n v o l v e d .  (16)  Streith  12  - 150  Thus by acid  -  a n a l o g y B e d f o r d and Money  l a c t o n e (17) s h o u l d g i v e m e t h y l  13  considered that  3,5-dioxohexanoate  triacetic (18) when 13  photolysed  i n methanol  t h a t the major  solution.  p r o d u c t formed  However t h e s e a u t h o r s  by p h o t o l y s i s  cis-|3-carbomethoxymethylcrotonic acid  was  amount (12%)  of ester  (18).  I t was  found  i n methanol  solution  (19), with only a  a l s o shown t h a t  minor  irradiation  Me0 C  C0 H  2  (17)  of pyrone  (17)  anhydride  (20) w h i c h  (18)  (19)  Minor  Major  i n e t h e r o r b e n z e n e gave ( S - m e t h y l g l u t a c o n i c i n methanol  converted into  acid  by  (21) and k e t e n e  invoking 0-lactone  (19) .  was  methoxymethylcrotonic  the 4 - h y d r o x y l group  affects  inducing irreversible  (19)  and An  c a n t h e n be  cis-^-carbo-  These r e s u l t s were (22) and  r e a c t i o n scheme i s shown i n F i g u r e I I .  (23) w h i c h  2  The  the r e a c t i v i t y  rearrangement  the  rationalised  proposed  authors suggest  that  o f ^ - l a c t o n e (21)  to a cyclobutenone  c o n v e r t e d to g l u t a c o n i c a c i d  derivative  derivatives  (20) . a l t e r n a t i v e mechanism f o r the p h o t o c h e m i c a l  o f oc-pyrones  to e s t e r s w i t h unrearranged  conversion  c a r b o n s k e l e t o n s has 14  r e c e n t l y been proposed  by M c i n t o s h and Chapman.  t h a t a d d i t i o n of methanol process, but  to ketene  (15)  They  propose  i s not I n v o l v e d i n t h i s  t h a t the p r i m a r y p h o t o r e a c t i o n i s a d d i t i o n  of  - 151  Figure!I:  Photochemistry  -  of t r i a c e t i c  acid  lactone  - . 152 -  m e t h a n o l t o one o f t h e d o u b l e bonds o f t h e p y r o n e . 4,6-dimethyl-<X-pyrone  (13) was p h o t o l y s e d i n m e t h a n o l t h e p r i m a r y  p h o t o p r o d u c t s were p y r o n e s subsequently  Thus when  (24) and (25) .  T h e s e compounds w e r e  o p e n e d by a c i d c a t a l y s e d m e t h a n o l y s i s  mixture of isomeric methyl  e s t e r s such  to give  a  as e s t e r ( 1 4 ) .  Me OH  II  S^*0  CO 2 Me  0  0  +  MeO  o  O  ^ 0  H /MeOH +  + other  C14)  isomers  - 153  -  DISCUSSION As  an  a l t e r n a t i v e method o f o p e n i n g p y r o n e r i n g s to  give  13 poly-|&-diketo-ester acid  lactone  chains  Bedford  (17), i n various  and  Money  photolysed  s o l v e n t s , hoping to o b t a i n e s t e r  However p h o t o l y s i s o f t r i a c e t i c  gave  c o n t a i n i n g o n l y a m i n o r amount o f e s t e r  (18)  of products  (10-15%),  the main p r o d u c t s  acid lactone  being  (17)  (18).  i n methanol  a mixture  compounds w i t h  rearranged  c a r b o n s k e l e t o n s , p - c a r b o m e t h o x y m e t h y l c r o t o n i c a c i d (19) f3 - m e t h y l g l u t a c o n i c  triacetic  anhydride  and  (20) .  (17)  (18)  (19)  (20)  I n an a t t e m p t t o i n c r e a s e  the y i e l d  unrearranged carbon s k e l e t o n t r i a c e t i c (26)  was  photolysed  i n methanol.  s o l u t i o n of methyl t r i a c e t i c  with  an  a c i d lactone methyl  P h o t o l y s i s o f a 0.2%  acid lactone  almost q u a n t i t a t i v e conversion  of product  (26)  ether  methanolic  resulted in  an  to a s i n g l e p h o t o p r o d u c t w h i c h  - 154  was  isolated  properties  -  as a c o l o u r l e s s o i l and  i n agreement w i t h the  the molecular, weight  was  found  had  spectral  and  analytical  assigned s t r u c t u r e (27).  (by mass s p e c t r o s c o p y )  Thus  t o be  172,  OMe h-0  MeOH  MeO OMe  indicating  t h a t m e t h a n o l had  ultraviolet  this  b e e n added t o m e t h y l  spectrum i n d i c a t e d  c h r o m o p h o r e a t 220  nm  proton  on  (6.68 t )  due  to a methyl  a double and  an  bond  o f the p h o t o p r o d u c t (19).  carbonyl  t h e i n f r a r e d s p e c t r u m showed  particularly  g r o u p on  (4.33*£), two  a double  o b t a i n e d by  The  bond  (8.02 t), a f  (7.45 "£).  c o n v e r s i o n , w i t h wet  to cis-ft-carbomethoxymethyl  ether,  crotonic acid  C0 Me 2  MeO (27)  groups  Confirmation  1 3  MeO'  nuclear  i n f o r m a t i v e , showing  equivalent methoxyl  i s o l a t e d methylene group  o f s t r u c t u r e (27) was  (26) ; t h e  an ^ - u n s a t u r a t e d S - l a c t o n e .  m a g n e t i c r e s o n a n c e s p e c t r u m was absorptions  ether  an «<^3 - u n s a t u r a t e d  (£ = 9,540) and  c h r o m o p h o r e c o u l d be  (27)  (19)  C0 H 2  - 155  The  conversion  -  of methyl ether  (26)  to dimethoxy pyrone  thus d i f f e r s markedly from the b e h a v i o u r of t r a i c e t i c (17)  as  t h e r e , i s no p r o d u c t f o r m e d w i t h  skeleton. formation  The  mechanism o f t h i s  of ^ - l a c t o n e  b i c y c l i c (3 - l a c t o n e of pyrone  (26)  has  (28)  (28). during  the  been o b t a i n e d  Methanol a d d i t i o n to ^ - l a c t o n e can now  open t h e r m a l l y  (30)  This  i s shown i n F i g u r e I I I .  is  which then c y c l i s e s  is interesting  condensation  low  by  (26)  of three  gives  of  rise  co-workers.  manner t o g i v e  acetate .units.  acid  type  1 5  t o a c i d (29)  which  dimethoxy (27).  acid lactone  which i s b i o s y n t h e s i s e d  compound t o a b r a n c h e d , s i x . c a r b o n  an  formation  de Mayo and  this  is  carbon  temperature p h o t o l y s i s  to note that t r i a c e t i c 1 6  lactone  involve  to give dimethoxy pyrone  a naturally occurring pyrone  linear  f o r the  i n a conrotatory  acid  It  an u n r e a r r a n g e d  r e a c t i o n seems t o  Evidence  acid  (27)  The  (17) by  conversion  compound o f t h e  of  glutaconic  might have s i g n i f i c a n c e i n t e r p e n o i d b i o s y n t h e s i s  a l t e r n a t i v e method o f d e r i v i n g m e v a l o n i c a c i d f r o m  as i t  three  molecules of a c e t i c a c i d . F u r t h e r work i s i n p r o g r e s s by w h i c h an e s t e r s u c h as p y r o n e converted  to devise (10)  i n t o a l i n e a r poly-|S-diketo  may  be  photochemically  e s t e r c o n t a i n i n g 8 carbon  atoms.  CO-Me 1  a l t e r n a t i v e methods  (10).  Figure  I I I : Photochemistry of methyl  triacetic  acid  lactone  -157  -  EXPERIMENTAL I r r a d i a t i o n e x p e r i m e n t s w e r e c o n d u c t e d a t room u n d e r d r y n i t r o g e n u s i n g an lamp ( H a n o v i a , was  magnesium m e t h o x i d e . and  mercury  450W) e q u i p p e d w i t h a p y r e x f i l t e r .  r i g o r o u s l y d r i e d by  block  i n t e r n a l water-cooled  are  the  formation  temperature  The  o f s m a l l amounts  methanol of  M e l t i n g p o i n t s w e r e d e t e r m i n e d on  uncorrected.  Infrared spectra  (\)  arc  a Kofler  ) were  recorded  m cix on  a Perkin-Elmer  violet  given  (A  spectra  U n i c a m SP  800  I n f r a c o r d m o d e l 137 ) were r e c o r d e d  i n parentheses.  Nuclear  the'Tiers ^  and  (M ) +  scale with  b.d  coupling constants  were d e t e r m i n e d w i t h  w e r e p e r f o r m e d by  Mr.  of B r i t i s h  r e s u l t s were o b t a i n e d  P.  an  (X)  an AEI  [where  m = multiplet. MS  on given  internal appropriate)  i n d i c a t e d i n parentheses;  = broad doublet,  are  S i g n a l p o s i t i o n s are  t e t r a m e t h y l s i l a n e as  i n t e g r a t e d peak a r e a s a r e  University  a  (£)  magnetic resonance s p e c t r a  spectrometer.  the m u l t i p l i c i t y ,  d = doublet,  i n m e t h a n o l s o l u t i o n on  i n c a r b o n t e t r a c h l o r i d e or deuteriochloroform  a V a r i a n A s s o c i a t e s A-60  standard;  Ultra-  spectrophotometer; e x t i n c t i o n c o e f f i c i e n t s  were r e c o r d e d  in  spectrophotometer.  Mass  9 spectrometer.  s =  singlet,  spectra  Microanalyses  Borda, M i c r o a n a l y t i c a l Laboratory,  Columbia.  Thin  using s i l i c a  l a y e r chromatographic ( t i c ) ?54  g e l HF"  J  o f 0.3  mm  thickness  and e l u t i n g w i t h c h l o r o f o r m . : a c e t i c a c i d ( 9 : 1 ) . I r r a d i a t i o n o f 4 - m e t h o x y - 6 - m e t h y l - 2 - p y r o n e (2,6) i n M e t h a n o l The of the  progress  light  b a n d a t 220  of the  r e a c t i o n was  a b s o r p t i o n b a n d a t 281 nm.  I t was  nm  f o u n d t h a t no  m o n i t o r e d by and  the  triacetic  the  disappearance  appearance of a acid lactone  new  methyl  - 158  ether  C26) r e m a i n e d  after  about  of  the product indicated  In  a t y p i c a l .run, t r i a c e t i c  t h a t one p h o t o p r o d u c t h a d b e e n  7.16 mmole) was i r r a d i a t e d  acid  ^max  H  7.45  2  2  0  n  &  m  =  9  '  5  4  0  C H g  1 2  o i l w i t h p h y s i c a l and  the assigned s t r u c t u r e ( 2 7 ) ,  ( C C 1 ) 1 7 3 0 , 1380 , 1360 , 850 c m " ; 1  m a x  ) ;  4  ^  (  C C 1 4  ( s , 2 H ) , 8.02 ( s , 3 H ) ; M  for  a colourless  consistent with  80°C (9 m m ) . - \ J  (480 m l ) f o r 6 h r .  gave a p a l e y e l l o w o i l ( 1 . 0 7 g, 96.5%)  w h i c h on d i s t i l l a t i o n y i e l d e d  b.p.  formed.  l a c t o n e m e t h y l e t h e r ( 2 6 ) ( 1 . 0 0 g,  i n methanol  E v a p o r a t i o n o f the methanol  chemical properties  6 h r I r r a d i a t i o n and t i c a n a l y s i s  0 : C, 55.82; H, 4  Conversion of photoproduct  +  )>  4  '  m/e  3 3  <>>  1 H  )>  6  -  6 8  Cs,  6 H  )>  1 7 2 ; C, 55.62; H, 6.88  (calc.  6.98). (27) t o c i s - / ? - c a r b o m e t h o x y m e t h y l -  ' c r 6 t o n i c a c i d (19) (a) P h o t o p r o d u c t  (27) ( 8 7 . 6 mg, 0.51 mmole) was d i s s o l v e d  s a t u r a t e d e t h e r (20 ml) a n d a l l o w e d t o s t a n d a t room for of  24 h r .  E v a p o r a t i o n to dryness  the s o l i d  n e e d l e s , m.p. 1650, (s, J  temperature  f o l l o w e d by r e c r y s t a l l i s a t i o n  r e s i d u e f r o m p e t r o l e u m e t h e r (60-80°C) gave  carbomethyoxymethylcrotonic acid 80-82°C ( l i t .  1270 , 1170 c m  _ 1  ;>  M e o H  i n water  cis-|S-  ( 1 9 ) ( 5 4 . 2 mg, 67.2%) as w h i t e  77- 78°C,-\) 213 nm  (£ =  1 H ) , 4.16 (m, 1 H ) , 6.30 ( b . d . , 2 H ) , 6.34 ( s , 3 H ) , 8.00 ( d ,  = 1.4 H z , 3 H ) .  (b) To a s o l u t i o n u s e d (27)  t o m e a s u r e t h e nmr s p e c t r u m  ("-30 mg i n 0.4 ml C C l ^ ) was added w a t e r  (2 d r o p s ) . P e r i o d i c  nmr a s s a y showed g r a d u a l d i s a p p e r a n c e o f p e a k s photoproduct  (2 7) and t h e a p p e a r a n c e  o f peaks  of photoproduct  corresponding to attributable to  - 159  cis-ft -carbometh.yoxymethylcroton.ic was  complete  exhibited  and  an nmr  -  acid  (19) .  a f t e r e v a p o r a t i o n to dryness spectrum  methoxymethylcrotonic  acid  identical (19) .  After  3 days  the s o l i d  t o that, o f p u r e  reaction  product  cis-^8-carbo-  - 160 BIBLIOGRAPHY  1.  J . N. C o l l i e , T r a n s .  Chem. S o c , 1 8 9 3 , 6_3,  329.  2.  J . N. C o l l i e , T r a n s .  Chem. S o c , 1 9 0 7 , 9_1 , 1 8 0 6 .  3.  J . N. C o l l i e  4.  A. J . B i r c h  5.  R. R o b i n s o n , "The S t r u c t u r a l C l a r e n d o n , O x f o r d , 1955.  6.  T. Money, Chem. R e v . , 1970 , 70_,  7.  T. Money, F. W. Comer, G. R. B. W e b s t e r , I . G. W r i g h t , a n d A. I . S c o t t , T e t r a h e d r o n , " 1967 , 2 3 , 3435.  a n d W. S. M e y e r s , J . Chem. S o c , 1 8 9 3 , 6_3, a n d F. W. D o n o v a n , A u s t r a l .  122.  J . Chem., 1 9 5 3 , 3_6,  360.  Relations of Natural Products", 553.  7a. J . L. D o u g l a s a n d T. Money, T e t r a h e d r o n ,  1967 , 2_3 , 3545.  8.  J . L. D o u g l a s a n d T. Money, C a n a d . J . Chem., 1967 , 4_5, 1 9 9 0 .  9.  J . L. D o u g l a s a n d T. Money, Canad. J . Chem., 1968 , 4_6 , 6 9 5 .  10.  C. T. B e d f o r d , J . L. D o u g l a s , Chem. Comm., 1 9 6 8 , 1 0 9 1 .  B. E. M c C a r r y ,  a n d T. Money,  11.  P. de Mayo, A d v . O r g . Chem., 1 9 6 0 , 2^ 3 9 4 .  12.  E. J . C o r e y 86, 9 5 0 .  13.  C. T. B e d f o r d  14.  C. L. M c i n t o s h a n d 0. L. Chapman, J . Amer. Chem. S o c , submitted f o r p u b l i c a t i o n . Appreciation i s gratefully a c k n o w l e d g e d t o P r o f e s s o r Chapman f o r i n f o r m a t i o n r e g a r d i n g his results prior to publication.  15.  J . P. G u t h r i e , C. L. M c i n t o s h , a n d P. de Mayo, Canad. J . Chem. , 1970 , 4_8 , 237 .  16.  T. M. H a r r i s , C. M. H a r r i s , A c t a , 1966 , 121 , 420 .  and J . S t r e i t h , J . Amer. Chem. S o c , 1 9 6 4 , a n d T. Money, Chem. Comm., 1 9 6 9 , 6 8 5 .  a n d R. J . L i g h t ,  Biochim.  Biophys.  

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