1,2-ASYMMETRIC INDUCTION IN THE ZWITTERIONIC CLAISEN REARRANGEMENT OFALLYLAMINES

A zwitterionic Claisen rearrangement has been developed for optically active N-allylpyrrolidines using a two-phase system. The inherent-1,2 asymmetric induction was investigated for the generation of a new C-C bond adjacent to a chiral C-O function. The reaction with acetyl chlor ide led to a small diastereomeric excess, whereas the rearrangement wi th propionyl chloride proceeded with a high simple and a high induced diastereoselection. The resulting gamma,delta-unsaturated amides were cyclized to the corresponding optically active gamma-butyrolactones, w hich are useful intermediates in natural product synthesis.