A Practical Asymmetric Synthesis of Isopropyl (1<i>R</i>,2<i>S</i>)-Dehydrocoronamate
作者:Wenjun Tang、Xudong Wei、Nathan K. Yee、Nitinchandra Patel、Heewon Lee、Jolaine Savoie、Chris H. Senanayake
DOI:10.1021/op200038y
日期:2011.9.16
A novel asymmetric synthesis of isopropyl (1R,2S)-dehydrocoronamate is described from (S)-1,2,4-butanetriol as the starting material in 28% overall yield. Highlights of this synthetic route include selective cyclopropanation between chiral cyclic sulfate 5 and diisopropyl malonate (8c), formation of vinylcyclopropane 3c via elimination of halide 4c, selective monohydrolysis of diisopropyl ester 3c
以(S)-1,2,4-丁三醇为起始原料,以28%的总收率描述了异丙基(1 R,2 S)-脱氢冕酸异丙酯的新型不对称合成。此合成途径的重点包括手性环硫酸酯之间的选择性环丙烷化5和二异丙基丙二酸二乙酯(图8c),形成乙烯基环丙烷的3C卤化物通过消除4c中,二异丙基酯的选择性单水解3C,和的酸Curtius重排10以形成异丙基(1 - [R ,2 S)-脱氢日冕酸盐TsOH盐13在> 99%ee中。仅涉及三个分离,该无色谱方法提供了快速和实用的获得(1 R,2 S)-1-氨基-2-乙烯基环丙烷-1-羧酸衍生物的途径。