Revisiting a Classic Approach to the <i>Aspidosperma</i> Alkaloids:  An Intramolecular Schmidt Reaction Mediated Synthesis of (+)-Aspidospermidine

Abstract

[reaction: see text] A total synthesis of (+)-aspidospermidine (1) is described. The key reactions used in the synthesis of this pentacyclic Aspidosperma alkaloid were a deracemizing imine alkylation/Robinson annulation sequence, a selective "redox ketalization", and an intramolecular Schmidt reaction. A Fischer indolization step carried out on a tricyclic ketone mirrored the sequence reported by Stork and Dolfini in their classic aspidospermine synthesis.