The Synthesis of Some Geometrical Diastereomers of 3-alkylbenzylidenecyclohexanes: Optical Rotatory Dispersion and Circular Dichroism Studies
Abstract
T reatm ent o f (3 R )-(+ )-3 -m e th y l and ( 3R) - ( + ) - 3 - t-b u ty lc y c lo h e x a n o n e s w ith b en zyltriphenylphosphonium c h lo rid e and base gave th e c o rre sp o n d in g o p ti c a ll y a c tiv e s ty re n e s ( 3 R )-(- ) - e l s - 3 -a e th y lb e n z y lld e n e c y c lo h e x a n e , ( 3R )- ( - ) - t r a n s - 3-a e th y lb e n z y lld e n e c y c lo h e x a n e , (3 R )-(+ ) - c is - 3 -J t-b u ty lbenzy lid en ecy clo h ex an e and (3 R )-(- ) - t r a n s -3 -t-b u ty lb e n z y lid e n e c y c lo h e x a n e . The ( 3R)- ( - )-m e th y le n e -3 -n e th y l and (3 R )-(- ) -m e th y le n e -3 -t-b u ty lc y c lo h e x a n e s were a ls o produced in a s im ila r fa s h io n . In o rd e r to determ ine geomet r i c a l c o n fig u ra tio n s th e co rresp o n d in g racem ic e l s and t r a n s - a l k y l - ben zy lid en ecy clo h ex an es were p rep ared In d ep en d en tly by aluminum d ic h lo ro - hy d rid e re d u c tio n o f t h e i r r e s p e c tiv e a l k y l- 2 -ben zy lid en ecy clo h ex an o n es p rep ared by c o n tro lle d co n d en satio n s o f 2 and U -alkylcyclohexanones w ith benzaldehyde in b a s e . ORD and CD s p e c tra in d ic a te th a t th e d ia s te re o m e ric 3 -m ethylb en zy lid en ecy clo h ex an es have s ty re n e chrooophores o f o p p o site c h i r a l i t y due to an o rth o phenyl p ro to n -c is a l l y l i c p ro to n s t e r i c in t e r a c t io n . The C otton e f f e c t s f o r th e t - b u t y l a n a lo g s, how ever, were n o t e n t ir e ly as e x p e c te d . The t r a n s - 3 - t - b u t y l compound had an ORD curve v ery s im ila r to th a t o f th e c o rresp o n d in g m ethyl isom er in d ic a tin g s i m i l a r i t i e s in co n fo rm atio n . The c la iso m er, how ever, had a unique ORD spectrum and t h i s may be in d ic a tiv e o f a n o n -c h a ir conform ation fo r t h i s compound. N egative p la in d is p e rs io n curves o b tain ed fo r th e m ethylene-3 -alk y lc y c lo h e x a n e s were examined w ith re s p e c t to th e a d d itiv ity o f ro ta to r y e f f e c t s in th e ORD curv es o f th e sty re n e compounds.
Degree
Ph.D.
Subject Area
Organic chemistry
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