Facile Transformation of 2-Azetidinones to 2-Piperidones:  Application to the Synthesis of the Indolizidine Skeleton and (8<i>S</i>,8a<i>S</i>)-Perhydro-8-indolizinol

Abstract

The highly functionalized bicyclic lactam 7 was prepared from diolefinic-2-piperidone 18 by the use of ruthenium-catalyzed RCM, and in turn, 18 was derived via a two-carbon addition process from readily accessible 4-olefinic-2-azetidinone 13. Bicyclic lactams 7 and 20 could serve as potentially valuable intermediates for the chiral synthesis of various hydroxylated indolizidine alkaloids as exemplified by the synthesis of (8S,8aS)-perhydro-8-indolizinol 19.