含有可阻转异构的膦-亚磷酸酯(P-OP)和手性C 2对称二胺(N-N)的RuCl 2(P-OP)(N-N)络合物(1)可以通过连续添加P轻松制备为反式异构体RuCl 2(PPh 3)3的–OP和N–N配体。对于这些络合物,已经观察到在室温下联芳基片段的快速阻转异构化。化合物反式- 1A干净异构成的混合物中的顺式异构体在EtOH在加热。DFT计算准确地再现了观察到的异构体的比例以及顺式的更大的热力学稳定性1a的异构体。配合物1是在非常温和的条件下,使用KO t Bu作为碱(4 bar H 2,室温,5 / 1 / KO t Bu = 500/1 / ,在非常温和的条件下,N-芳基亚胺5在甲苯中不对称氢化的有效催化剂前体。10)。在催化剂前体中,1f可在多种N-芳基亚胺的氢化反应中提供良好的对映选择性(84-96%ee,16个实例)。从DFT计算中,提出了一种机制,其中包括将氢化物和质子从二氢
An oxidative kinetic resolution of racemic acyclic amines was developed using an imine derivative as the resolving reagent and chiral phosphoric acid as the catalyst to give enantiomers in good yields with high to excellent enantioselectivities. The key to success of the title reaction was the equilibrium control by adjusting the ratio of the resolving reagent, and unique enantiodivergence was observed
Scope of the organocatalysed asymmetric reductive amination of ketones with trichlorosilane
作者:François-Moana Gautier、Simon Jones、Xianfu Li、Stephen J. Martin
DOI:10.1039/c1ob05965c
日期:——
A highly active organocatalyst has been shown to affect the asymmetric reductive amination of ketones producing both aromatic and aliphatic amines. At 1 mol% catalyst loading, a series of structurally diverse chiral amines were quickly and economically prepared with good enantioselectivity and generally useful yield. The efficient synthesis of the calcimimetic (+)-NPS R-568 (67%, 89% ee) demonstrated the synthetic applicability of this methodology.
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
The first enantioselective Bronsted acidcatalyzedreduction of imines has been developed. This new organocatalytic transfer hydrogenation of ketimines with Hantzsch dihydropyridine as the hydrogen source offers a mild method to various chiral amines with high enantioselectivity. The stereochemistry of the chiral amines can be rationalized by a stereochemical model derived from an X-ray crystal structure