Evidence of the electronic factor for the highly enantioselective catalytic efficiency of Cinchona-derived phase-transfer catalysts

MS Yoo, BS Jeong, JH Lee, H Park, S Jew

Index: Yoo, Mi-Sook; Jeong, Byeong-Seon; Lee, Jeong-Hee; Park, Hyeung-Geun; Jew, Sang-Sup Organic Letters, 2005 , vol. 7, # 6 p. 1129 - 1131

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Citation Number: 69

Abstract

The Cinchona alkaloid-derived quaternary ammonium salts containing 2'-N-oxypyridine and 2'-cyanobenzene moieties were prepared and evaluated as phase-transfer catalysts in the enantioselective alkylation of glycine imine ester 1. The N-oxypyridine and cyanobenzene moieties might play an important role to form a rigid conformation by coordinating with H2O via hydrogen bonding leading to high enantioselectivity (97~> 99% ee), which provides ...