Asymmetric Cyanation of Aldehydes, Ketones, Aldimines, and Ketimines Catalyzed by a Versatile Catalyst Generated from Cinchona Alkaloid, Achiral Substituted 2,2′-Biphenol and Tetraisopropyl Titanate
作者:Jun Wang、Wentao Wang、Wei Li、Xiaolei Hu、Ke Shen、Cheng Tan、Xiaohua Liu、Xiaoming Feng
DOI:10.1002/chem.200900936
日期:2009.11.2
Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)4] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved
通过使用由金鸡纳生物碱,钛酸四异丙酯[Ti(O i Pr )4 ]和非手性改性双酚。使用TMSCN作为氰化物源,N -Ts(Ts =对甲苯磺酰基)的亚胺和酮亚胺(产率> 99%和ee > 99%)的Strecker反应取得了良好或优异的结果。酮氰化(产率高达99%,ee高达98%))。通过使用CNCOOEt作为替代氰化物源,完成了醛的氰化反应,制备了各种对映体富集的氰醇碳酸盐,收率高达99%,ee高达96%。值得注意的是,CNCOOOET首次成功地用于醛亚胺和酮亚胺的不对称Strecker反应中,从而提供了各种具有优异收率和ee值(高达> 99%收率和> 99%ee的α-氨基腈))。当前方案的优点包括容易获得的配体组分,操作简便和反应条件温和,这使得制备合成上重要的手性氰醇和α-氨基腈变得很方便。此外,进行了对照实验和NMR分析以阐明催化剂的结构。结果表明,金鸡纳生物碱和双酚中的所有羟基均与Ti