A concise enantiospecific synthesis of nuphar piperidine alkaloids: total synthesis of (–)-anhydronupharamine, (–)-nupharamine, (–)-nuphenine and (+)-3-epinupharamine

Abstract

Enantiospecific syntheses of (–)-anhydronupharamine, (–)-nupharamine, (–)-nuphenine, and (+)-3-epinupharamine are achieved starting from (–)-or (+)-carvone as chiral sources, in which a regioselective reductive fragmentation of the cyclopentane derivatives and an intramolecular aza–Wittig reaction were involved as key reactions.