Conjugate Addition of Lithiated (S)-4-Isopropyl-3- [(methylthio)methyl]-5,5-diphenyloxazolidin-2-one to Cinnamoyl Derivatives: Preparation of Enantiomerically Pure 1,4-Diols
作者:Christoph Gaul、Dieter Seebach
DOI:10.1002/1522-2675(200203)85:3<772::aid-hlca772>3.0.co;2-i
日期:2002.3
The Li derivative of (S)-4-isopropyl-3-[(methylthio)methyl]-5,5-diphenyloxazolidin-2-one (Li-2; synthetically equivalent to a chiral formyl anion) adds to enones and enoates in a 1,4-fashion. Best results are obtained with 1,3-diarylpropenones (chalcones; Scheme 2), trityl enones, and 2,6-di(tert-butyl)-4-methoxyphenyl cinnamates (Scheme 3), with yields up to 80% and diastereoselectivities up to and
(S)-4-isopropyl-3-[(methylthio)methyl]-5,5-diphenyloxazolidin-2-one(Li-2;合成上相当于手性甲酰基阴离子)的 Li 衍生物与烯酮和烯酸酯加成1,4-时尚。使用 1,3-二芳基丙烯酮(查耳酮;方案 2)、三苯甲基烯酮和 2,6-二(叔丁基)-4-甲氧基苯基肉桂酸酯(方案 3)可获得最佳结果,产率高达 80%,非对映选择性提高到 99 及以上:1 个产品(5a-f 和 8a、b、e)包含三个立体中心!X 射线晶体结构分析表明,C、C 键的形成优先发生在相对局部性 ul(Re/Si;图 2)中。在 Hg2+ 辅助取代中,1,4-加合物的 MeS 基团可以被 RO 基团取代,随后手性助剂的去除和容易回收(方案 4-6)。4-羟基羰基衍生物('homoaldols')和单-,