A Highly Efficient Conversion of a Simple Derivative of the Amino Acid Proline into a Nearly Enantiomerically Pure N-Protected Allyl Amine: Use of Thionyl Chloride to Promote the Peterson Olefination
作者:Guoqing Wei、Theodore Cohen
DOI:10.1055/s-0031-1289536
日期:2011.11
A novel two-step conversion of an N-Boc methyl ester of the natural aminoacid proline into highly enantioenriched N-Boc 2-vinylpyrrolidine is described. Key steps include (1) an SNi displacement of a methoxygroup of the DIBAL-H adduct of the starting ester by the TMSCH2 group of the corresponding Grignard reagent, and (2) the use of thionyl chloride to promote the Peterson olefination of the resulting
描述了天然氨基酸脯氨酸的N -Boc甲酯向高度对映体富集的N -Boc 2-乙烯基吡咯烷的新型两步转化。关键步骤包括(1)TMSCH 2对起始酯的DIBAL-H加合物的甲氧基进行S N i置换(2)使用亚硫酰氯促进所得到的带有与醇官能团相邻的立体中心的β-羟基硅烷的彼得森烯化反应。在温和的条件下,整个转化过程具有显着的便利性,几乎没有丧失立体化学完整性。在消除步骤中必须使用亚硫酰氯,因为碱性和酸性条件均与Boc保护基不相容。与相应的N-保护的氨基醛的标准Wittig烯化形成鲜明对比的是,其中发生了8-10%的消旋化(80-84%ee),在这种新方法中仅观察到约1%的消旋化(98%ee)。 烯丙胺-氨基酸-手性库-吡咯烷-烯化