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Highly Efficient Formal [2+2+2] Strategy for the Rapid Construction of Polycyclic Spiroindolines: A Concise Synthesis of 11‐Demethoxy‐16‐ epi ‐myrtoidine
Author(s) -
Zhu Jun,
Cheng YuJing,
Kuang XiaoKang,
Wang Lijia,
Zheng ZhongBo,
Tang Yong
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201603991
Subject(s) - tryptamine , stereoselectivity , formal synthesis , chemistry , malonate , indole test , combinatorial chemistry , stereochemistry , methylene , yield (engineering) , strychnos , total synthesis , catalysis , organic chemistry , alkaloid , materials science , biochemistry , metallurgy
A novel formal [2+2+2] strategy for the stereoselective elaboration of polycyclic indole alkaloids is described. Upon treatment with the catalyst InCl 3 (5 mol %), tryptamine‐derived enamides reacted readily with methylene malonate, thus enabling rapid and gram‐scale access to versatile tetracyclic spiroindolines with excellent diastereoselectivity (21 examples, up to 95 % yield, up to d.r.>95:5). This strategy provides a concise approach to alkaloids isolated from Strychnos myrtoides , as demonstrated by a short synthesis of 11‐demethoxy‐16‐ epi ‐myrtoidine.