Cooperative Catalysis: Combining an Achiral Metal Catalyst with a Chiral Brønsted Acid Enables Highly Enantioselective Hydrogenation of Imines
作者:Weijun Tang、Steven Johnston、Chaoqun Li、Jonathan A. Iggo、John Bacsa、Jianliang Xiao
DOI:10.1002/chem.201302437
日期:2013.10.11
Asymmetric hydrogenation of imines leads directly to chiral amines, one of the most important structural units in chemical products, from pharmaceuticals to materials. However, highly effective catalysts are rare. This article reveals that combining an achiral pentamethylcyclopentadienyl (Cp*)–iridium complex with a chiral phosphoric acid affords a catalyst that allows for highly enantioselective hydrogenation
亚胺的不对称氢化直接导致手性胺,从药物到材料,化学产品中最重要的结构单元之一。然而,高效催化剂是罕见的。本文表明,将非手性五甲基环戊二烯基(Cp *)-铱配合物与手性磷酸结合使用可提供一种催化剂,该催化剂可对源自芳基酮和脂肪族酮的亚胺与ee进行高度对映选择性氢化值从81%到98%不等。研究了一系列含有二胺配体的非手性铱配合物,表明该配体对反应速率,对映选择性和催化剂失活具有深远的影响。手性磷酸同样重要,在氢化反应中引起对映异构。然而,诱导发生是以反应速率为代价的。