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.