Asymmetric Synthesis of 1,2,3-Trisubstituted Cyclopentanes and Cyclohexanes as Key Components of Substance P Antagonists
作者:Jeffrey T. Kuethe、Audrey Wong、Jimmy Wu、Ian W. Davies、Peter G. Dormer、Christopher J. Welch、Michael C. Hillier、David L. Hughes、Paul J. Reider
DOI:10.1021/jo025883m
日期:2002.8.1
An efficient asymmetric synthesis of 1,2,3-trisubstituted cyclopentanes and cyclohexanes is described. Three methods were developed for the preparation of the 2,3-disubstituted cyclopentenones and cyclohexenones, which are key achiral building blocks. These intermediates are reduced catalytically with (R)-2-methyloxazaborolidine in high yield (82-98%) and excellent ee (89-96%). Directed reduction of
描述了1,2,3-三取代的环戊烷和环己烷的有效不对称合成。开发了三种方法来制备2,3-二取代的环戊烯酮和环己烯酮,这是关键的非手性构建单元。这些中间体可以用(R)-2-甲基恶唑硼烷催化还原,产率高(82-98%)和优良的ee(89-6%)。使用Red-Al直接还原手性烯丙基醇只能得到1,2-抗立体化学(> 99:1)。酯中心的差向异构化,然后进行皂化/结晶,以良好的收率(65-70%)和高的对映体过量(> 99%)提供所需的羟基酸。