Unusual Diastereoselection in the Synthesis of Nine-Membered Ring Lactams and Conformation-Controlled Transannular Reactions to Generate Optically Active Indolizidinones

Abstract

The aza-Claisen rearrangement of vinylpyrrolidines 1 yielded almost exclusively the trans-3,8-disubstituted nine-membered ring lactams 2 (TBS=tBuMe2Si), independent of whether cis or trans isomers were used as starting materials. The conformation (which provided facial chirality) of the medium-sized ring controlled the regio- and diastereoselectivities of the transannular reactions that afforded indolizidinones 3.