Unusual Diastereoselection in the Synthesis of Nine-Membered Ring Lactams and Conformation-Controlled Transannular Reactions to Generate Optically Active Indolizidinones
yielded almost exclusively the trans-3,8-disubstituted nine-membered ring lactams 2 (TBS=tBuMe2 Si), independent of whether cis or trans isomers were used as starting materials. The conformation (which provided facial chirality) of the medium-sizedring controlled the regio- and diastereoselectivities of the transannularreactions that afforded indolizidinones 3.