Asymmetric synthesis of cyclic alkenes via cyclization of enantioenriched allylsilanes

Intramolecular cyclizations of optically active allylsilanes bearing electr ophilic functional groups on their alpha -alkyl side chains were examined. The allylsilanes having aldehyde and enone functional groups underwent the intramolecular cyclizations in the presence of Lewis acid catalysts to give 6- and 7-membered cycloalkenes with high stereoselectivity in good yields. Reactions of the allylsilanes having a-hydroxyalkyl chain with aldehydes p rovided 6- and 7-membered oxacycloalk-4-enes stereoselectively in good yiel ds. Use of highly enantioenriched allylsilanes furnished enantioenriched cy clic alkenes with almost perfect chirality transfer from the allylsilanes.