Radical cyclizations of acylsilanes in the synthesis of (+)-swainsonine and formal synthesis of (−)-epiquinamide
作者:Ming-Jen Chen、Yeun-Min Tsai
DOI:10.1016/j.tet.2010.12.048
日期:2011.2
form the indolizidine skeleton through a 1,6-cyclization. In the second approach, (S)-(+)-5-oxo-2-tetrahydrofurancarboxylic acid (23) was used to construct the same ring system through a 1,5-cyclization. Starting from acid 23, we also synthesized exo-1-hydroxyquinolizidin-4-one (56), which was a synthetic intermediate in the synthesis of polyhydroxylated quinolizidine (−)-epiquinamide.
酰基硅烷的自由基环化是一种有用的合成方法。为了证明该方法以环化为关键步骤的多功能性,通过两种不同的键连接方法合成了多羟基化的吲哚并吡啶(+)-swainsonine,以构建双环骨架。在第一种方法中,我们使用2,3-异亚丙基d -ribono -1,4-内酯(20)作为手性结构单元,以形成通过1,6-环化的吲嗪啶骨架。在第二种方法中,使用(S)-(+)-5-氧代-2-四氢呋喃羧酸(23)通过1,5-环化反应构建相同的环系统。从酸23开始,我们还合成了exo -1-hydroxyquinolizidin-4-one(56),其是多羟基化喹oli嗪(-)-表喹酰胺的合成中的合成中间体。