A General Synthetic Entry to <i>Strychnos</i> Alkaloids of the Curan Type via a Common 3a-(2-Nitrophenyl)hexahydroindol-4-one Intermediate. Total Syntheses of (±)- and (−)-Tubifolidine, (±)-Akuammicine, (±)-19,20-Dihydroakuammicine, (±)-Norfluorocurarine, (±)-Echitamidine, and (±)-20-Epilochneridine<sup>1</sup>
作者:Josep Bonjoch、Daniel Solé、Silvina García-Rubio、Joan Bosch
DOI:10.1021/ja970347a
日期:1997.8.1
general strategy for the synthesis of pentacyclic Strychnos alkaloids with the curan skeleton has been developed. It utilizes 3a-(2-nitrophenyl)hexahydroindol-4-one (23), which was prepared from 2-allyl-2-(2-nitrophenyl)-1,3-cyclohexanedione (15), as the common, pivotal intermediate. Three different procedures have been employed for the closure of the bridged piperidine D ring from 23: (i) an intramolecular
已开发出合成具有curan 骨架的五环马钱子生物碱的一般策略。它使用由 2-烯丙基-2-(2-硝基苯基)-1,3-环己二酮 (15) 制备的 3a-(2-硝基苯基)六氢吲哚-4-酮 (23) 作为常见的关键中间体。已采用三种不同的程序来闭合来自 23 的桥连哌啶 D 环: (i) 分子内迈克尔型共轭物加成;(ii) Ni(COD)2 促进的双环化,在单个合成步骤中组装 B 和 D 环,以及 (iii) 烯酮-炔丙基硅烷系统的分子内环化。必要时,根据所使用的程序,在 C-16 处引入氧化的单碳取代基,关闭吲哚环,和/或调整 C-20 二碳链的功能构成了标题生物碱合成路线的最后阶段。涉及炔丙基硅烷环化的过程已成功扩展到对映特异性……