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Asymmetric Cyanosilylation of Ketones Catalyzed by Bifunctional Chiral N ‐Oxide Titanium Complex Catalysts
Author(s) -
Shen Yongcun,
Feng Xiaoming,
Li Yan,
Zhang Guolin,
Jiang Yaozhong
Publication year - 2004
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200300415
Subject(s) - chemistry , bifunctional , catalysis , enantioselective synthesis , enantiomer , oxide , bifunctional catalyst , asymmetric induction , titanium , enantiomeric excess , pyrrolidine , organic chemistry , medicinal chemistry
A new bifunctional catalytic system based on chiral N ‐oxide titanium complexes has been used for the asymmetric cyanosilylation of ketones. Screening of a variety of chiral N ‐oxide metal complexes resulted in (1 R ,2 S )‐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 based on experimental phenomena and studies was proposed to explain the origin of the asymmetric induction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)