Stereocontrolled synthesis of piperidine alkaloids, (-)-241D and (-)-isosolenopsin

Highly diastereocontrolled synthesis of alkaloids, (-)-241D and (-)-isosolenopsin was achieved in 7.7% and 5.3% yields, respectively, using a Barbier-type allylation of a chiral imine and D-proline catalyzed aldol addition reaction of a beta-amino aldehyde with acetone as the key steps. The synthesis involves a nine-step sequence using (S)-valinate imine in a Barbier-type allylation for the first time. (C) 2012 Elsevier Ltd. All rights reserved.