Highly Stereoselective Total Synthesis of Fully Hydroxy-Protected Mycolactones A and B and Their Stereoisomerization upon Deprotection
作者:Guangwei Wang、Ning Yin、Ei-ichi Negishi
DOI:10.1002/chem.201002627
日期:2011.4.4
Unprecedentedly efficient and highly (≥98 %) stereoselective syntheses of mycolactones A and B side chains relied heavily on Pd‐catalyzed alkenylation (Negishi version) and were completed in 11 longest linear steps from ethyl (S)‐3‐hydroxybutyrate in 12 % and 11 % overall yield, respectively, roughly corresponding to an average of 82 % yield per step. The synthesis of mycolactone core was realized by using Pd‐catalyzed
真菌内酯 A 和 B 侧链的前所未有的高效和高度(≥98 %)立体选择性合成严重依赖于 Pd 催化的烯基化(Negishi 版本),并在 11 个最长的线性步骤中完成,从12% 的( S )-3-羟基丁酸乙酯和分别为 11% 的总产率,大致对应于每步平均 82% 的产率。Mycolactone核心的合成是通过使用Pd催化的烯基烯丙基偶联和与三烷基烯基铝酸盐的环氧化物开环反应作为关键步骤来实现的。首次成功合成了异构纯度≥98%的完全羟基保护的支链菌内酯A和B。然而,在脱保护后获得了出乎意料的 4:3-5:4 不可分离的支链内酯 A 和 B 混合物。