Stereoselective synthesis of lycoranes (2,3,3a,4,5,7-tetrahydro-1H-pyrrolo[3,2,1-de]phenanthridines) derived from alkaloids lycorine and caranine

Abstract

Three stereoisomeric lycoranes (2,3,3a,4,5,7-tetrahydro-1H-pyrrolo[3,2,1-de]phenanthridines), α-, β-, and δ-lycorane, derived from the Amaryllidaceae alkaloids lycorine and caranine were stereoselectively synthesised from two stereoisomeric 3-(3,4-methylenedioxyphenyl)-1,2,3,6-tetrahydrophthalic anhydrides obtained by Diels–Alder reaction of 1-(3,4-methylenedioxyphenyl)but-3-en-1-ol and fumaric acid.