An updated asymmetric total synthesis of (+)-tronocarpine

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 C-20 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. (C) 2020 Elsevier Ltd. All rights reserved.