ACID-PROMOTED REARRANGEMENT OF CYCLIC ALPHA,BETA-EPOXY ACYLATES - STEREOSELECTIVE SYNTHESIS OF SPIROCYCLANES AND QUATERNARY CARBON CENTERS

The rearrangement reaction of alpha,beta-epoxy acylates in cyclic syst ems was studied. The treatment of cis-derivatives with a Lewis acid af forded rearranged products via the regioselective B-cleavage of the ox irane ring due to the electron-withdrawing nature of the acyloxy group , whereas trans-derivatives enhanced the neighboring group participati on to yield only a small amount of rearranged products. This rearrange ment reaction proved to be useful for the construction of st variety o f spirocyclane systems or quaternary carbon centers on rings and could be applied to their syntheses as optically active forms.