Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Total Synthesis of (−)‐17‐nor‐Excelsinidine

• DOI: 10.1002/anie.201802610
• Publication Date: 2018-03-25T07:09:27Z
• Authors: Maxime Jarret; Aurélien Tap; Cyrille Kouklovsky; Erwan Poupon; Laurent Evanno; Guillaume Vincent
• Keywords: Monoterpene; Indole alkaloid

We report the first total synthesis of (-)-17-nor-excelsinidine, a zwitterionic monoterpene indole alkaloid that displays an unusual N4-C16 connection. Inspired by postulated biosynthesis, we explored oxidative coupling approach from geissoschizine framework to forge key ammonium-acetate Two strategies allowed us achieve this goal, namely intramolecular nucleophilic substitution on 16-chlorolactam with N4 nitrogen atom or direct I2 -mediated enolate geissoschizine.