Asymmetric Cyanosilylation of Ketones Catalyzed by Bifunctional ChiralN-Oxide Titanium Complex Catalysts
作者:Yongcun Shen、Xiaoming Feng、Yan Li、Guolin Zhang、Yaozhong Jiang
DOI:10.1002/ejoc.200300415
日期:2004.1
A new bifunctional catalytic system based on chiral N-oxide titanium complexes has been used for the asymmetric cyano-silylation of ketones. Screening of a variety of chiral N-oxide metal complexes resulted in (1R,2S)-1-(2'-pyridylmethyl)-2-(diphenylhydroxymethyl)pyrrolidine N-oxide titanium complex, which gave O-TMS cyanohydrins in good yields with enantiomeric excesses of up to 69%. A catalytic cycle
基于手性 N-氧化物钛配合物的新型双功能催化体系已用于酮的不对称氰基硅烷化。筛选各种手性 N-氧化物金属配合物产生 (1R,2S)-1-(2'-吡啶基甲基)-2-(二苯基羟甲基)吡咯烷 N-氧化物钛配合物,从而以良好的收率得到 O-TMS 氰醇对映体过量高达 69%。提出了基于实验现象和研究的催化循环来解释不对称诱导的起源。((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)。