Air-Stable, Storable, and Highly Selective Chiral Lewis Acid Catalyst
摘要:
[GRAPHICS]An air-stable, storable, and highly selective chiral Lewis acid catalyst for asymmetric Mannich-type reactions has been developed, The catalyst can be stored for more than three months in air at room temperature without loss of activity, Moreover, it has also been demonstrated that the catalyst can be recovered and reused.
Remarkably Stable Chiral Zirconium Complexes for Asymmetric Mannich-Type Reactions
作者:Kowichiro Saruhashi、Shū Kobayashi
DOI:10.1021/ja062776r
日期:2006.8.1
Isolable, air-stable, storable, and highly selective chiral zirconium catalysts for asymmetric Mannich-type reactions have been developed. The reactions of imines with silicon enolates proceeded smoothly using 1-10 mol % of the powdered zirconium catalyst to afford the corresponding adducts in high yields with high stereoselectivities. The catalyst could be recovered and reused without significant
已开发出用于不对称曼尼希型反应的可分离、空气稳定、可储存和高选择性手性锆催化剂。使用 1-10 mol% 的粉状锆催化剂,亚胺与硅烯醇化物的反应顺利进行,以高收率和高立体选择性提供相应的加合物。催化剂可以回收和再利用而不会显着损失活性。另一方面,获得了用于 X 射线分析的锆单晶,该晶体在不对称 Mannich 型反应中也表现出高性能。尽管这些锆催化剂的 NMR 分析显示在二氯甲烷中具有不同的结构,但表明不同催化剂形成了相同的关键中间体。
An air-stable chiral Hf-based catalyst for asymmetric Mannich-type reactions
A new class of isolable, air-stable, storable, and Hf-based catalyst has been developed. In the presence of 10 mol% of the powdered Hf catalyst, the asymmetric Mannich-type reactions of imines with silicon enolates derived from esters proceeded smoothly to afford the corresponding Mannich-type adducts in high yields with high enantioselectivities. Hafnium single crystals for X-ray analysis were obtained, and the crystals also showed high performance in the asymmetric Mannich-type reactions. (c) 2007 Published by Elsevier Ltd.