An updated asymmetric total synthesis of (+)-tronocarpine

Abstract An updated route for the asymmetric total synthesis of (+)-tronocarpine is presented. By a careful modification of the synthetic strategies and methods for the construction of azepanone ring and for the incorporation of acetyl side group at C20 based on our experiences for the synthesis of chippiine-dippinine type indole alkaloids, the synthesis of (+)-tronocarpine could be shortened from 15 longest linear sequences (LLSs) to 11 LLSs starting from an easily prepared intermediate. The new synthetic route presented herein would provide a more efficient synthesis of (+)-tronocarpine as well as its analogues for biological evaluation which remained unexplored due to the paucity of natural sources.