Asymmetric catalysis: A facileenantioselective Strecker reaction of ketimines with trimethylsilyl cyanide (TMSCN) was realized by employing chiral (S)‐BNPNa 3 e and PBAP as an additive (see image). A wide substrate scope and good‐to‐excellent enantioselectivities were achieved.
Catalyst loading as low as 0.1 mol % was achieved in the enantioselectiveStreckerreaction of ketoimines. Excellent enantioselectivity was obtained with a combined use of a catalytic amount of TMSCN and a stoichiometric amount of HCN as a reagent, and a chiral gadolinium complex as a catalyst.
demonstrate novel properties as asymmetric catalysts. We report the three-dimensional structures of two such asymmetric catalysts (crystals A and B) for Strecker alpha,alpha-disubstituted amino acidsynthesis. These complexes are constructed via assembly of the same chiral modules derived from d-glucose, but their assembly modes differ. The enantioselectivity in the Strecker reaction was dramatically switched
自组装手性多金属配合物通常表现出作为不对称催化剂的新特性。我们报告了用于 Strecker α、α-二取代氨基酸合成的两种这种不对称催化剂(晶体 A 和 B)的三维结构。这些复合物是通过组装来自 d-葡萄糖的相同手性模块构建的,但它们的组装模式不同。Strecker 反应中的对映选择性发生了显着变化,具体取决于使用的组装模式:原位生成的催化剂,其结构由晶体 B 或晶体 A 表示。这些发现提供了对高阶结构的功能重要性的洞察一种人工催化剂。
Enantioselective Strecker-type reaction of phosphinoyl ketimines catalyzed by a chiral Zr-bipyridyldiol catalyst
作者:Yi-Jing Chen、Chinpiao Chen
DOI:10.1016/j.tetasy.2008.09.011
日期:2008.9
An enantioselective Strecker reaction of N-diphenylphosphinoyl ketimines with TMSCN employing a chiral zirconium complex formed from chiral bipyridyl diol 1 as catalyst is described. The catalytic efficiency of chiral ligand 1 with other Lewis acids was also explored. Higher yields (50-85%) with moderate to good enantioselectivities (30-80%) were achieved for a variety of N-diphenylphosphinoyl ketimines. (C) 2008 Elsevier Ltd. All rights reserved.
General and practical catalytic enantioselective Strecker reaction of ketoimines: significant improvement through catalyst tuning by protic additives
Significant improvement in enantioselectivity and catalyst activity was achieved for the catalytic enantio selective Strecker reaction. Using a catalyst (1-2.5 mol%) prepared from Gd((OPr)-Pr-i)(3) and D-glucose derived ligand 1, and in the presence of 2,6-dimethylphenol as an additive, high enantioselectivity was obtained from a wide range of ketoimines, including heteroaromatic and cyclic ketoimines. The new method was applied to an efficient catalytic asymmetric synthesis of sorbinil, a therapeutic agent for diabetic complications. (C) 2004 Elsevier Ltd. All rights reserved.