Retro-biosynthetic construction of corynanthe alkaloid skeletons from rhynchophylline alkaloids.

Rhynchophylline alkaloids are bio-synthesized from corynanthe alkaloids via an oxidative rearrangement. We demonstrate here that corynanthe alkaloids could be generated from rhynchophylline alkaloids in a retro-biosynthetic manner via a Wagner-Meerwein rearrangement. A series of corynanthe analogues were afforded with good functional group tolerance and satisfactory yields.