Preparation of Chiral Amino Esters by Asymmetric Phase-Transfer Catalyzed Alkylations of Schiff Bases in a Ball Mill
作者:Pierrick Nun、Violaine Pérez、Monique Calmès、Jean Martinez、Frédéric Lamaty
DOI:10.1002/chem.201102885
日期:2012.3.19
The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine
在球磨机中在碱性条件下进行席夫碱的不对称烷基化。甘氨酸的起始席夫碱是通过在没有溶剂的情况下将受保护的甘氨酸盐酸盐和二苯甲酮亚胺研磨而制备的。然后在KOH存在下,在球磨机中使席夫碱与卤代衍生物反应。通过添加衍生自辛可尼定的手性铵盐,该反应在相转移催化条件下不对称进行,获得了出色的收率,对映体过量高达75%。因为使用了等摩尔量的原料,所以大大简化了纯化。