Formal Synthesis of Aspidospermidine via the Intramolecular Cascade Transannular Cyclization

Abstract

A formal synthesis of aspidospermidine is reported through a novel preparation of Stork’s penultimate tricyclic ketone intermediate. The key steps of the synthesis consist of an intramolecular cascade transannular cyclization, triggered by the removal of Boc group, which simultaneously forms the C, D, and E rings of aspidospermidine and conveniently setting up the quaternary stereo­center via decarboxylative alkylation reaction of the β-keto ester.