Synthesis of (+)-coniceine via reductive photocyclization of dienamides: an entry to indolizidines

This paper describes the establishment of a new synthetic route to the hydrobromide salt of (+)-coniceine 1 with high enantiopurity in five steps and 8% overall yield. The key step is the reductive photocyclization of an acyclic chiral dienamide, for which a convenient one-pot synthesis is described. (c) 2007 Published by Elsevier Ltd.