A Stereoselective Approach toward (-)-Lepadins A-C.

A new short approach to (-)-lepadins A-C has been developed based on a stereocontrolled Diels-Alder reaction employing a chiral dienophile. With this approach, (-)-lepadin B is synthesized from 5-deoxy-d-ribose in 13 steps with 14.8% overall yield. The cis-decahydroquinoline core containing five stereocenters could be rapidly constructed via stereoselective cycloaddition and subsequent five-step one-pot hydrogenation-cyclization.