Enantioselective Total Synthesis of (+)‐Nordasycarpidone, (+)‐Dasycarpidone, and (+)‐Uleine

Abstract

AbstractThe structure of uleine type alkaloids is characterized by the presence of a bridged tetracyclic hexahydro‐1H‐1,5‐methanoazocino[4,3‐b]indole ring system 1. Various strategies have been developed to access this polycyclic structural motif. We report herein a one‐step conversion of appropriately functionalized 1,3,4‐trisubstituted cyclopent‐1‐ene to 1 by way of an integrated oxidation/reduction/cyclization (iORC) process. This domino sequence, initiated by oxidative cleavage of cyclopentene ring, generated subsequently a cyclohexenone, an indole and a 1,3‐bridged piperidine ring through formation of one C−C and two C−N bonds. Compound 1 is subsequently converted to nordasycarpidone, dasycarpidone and uleine. The chirality of the molecule was introduced by enzymatic desymmetrization of commercially available meso cis‐3,5‐diacetoxy‐1‐cyclopentene.