A Divergent Polyene Cyclization for the Total Synthesis of Greenwayodendrines, Greenwaylactams, Polysin and Polyveoline

Abstract

AbstractWe present a concise asymmetric total synthesis (5–8 steps) of nine sesquiterpenoid alkaloids featuring four different tetra‐/pentacyclic scaffolds. To this end, a novel, bioinspired indole N‐terminated cationic tricyclization has been developed, enabling the divergent synthesis of greenwayodendrines and polysin. Subtle variation of the C2‐substituted indole cyclization precursor allowed switching between indole N‐ and C‐termination. For the latter, a subsequent Witkop oxidation enabled conversion of the cyclopentene‐fused indole into the eight‐membered benzolactam to directly furnish the family of greenwaylactams. In addition, a diastereomeric C‐termination product has been elaborated to provide access to polyveoline.