A Chiral Bifunctional Sulfonamide as an Organocatalyst: Alcoholysis of σ-Symmetric Cyclic Dicarboxylic Anhydrides
作者:Shigeki Sano、Takashi Honjo、Takeshi Tsumura、Yoshimitsu Nagao、Kentaro Yamaguchi、Yoshihisa Sei
DOI:10.1055/s-0029-1218374
日期:2009.12
Enantioselective alcoholysis of σ-symmetric cyclicdicarboxylicanhydrides with benzyl alcohol catalyzed by a chiralbifunctionalsulfonamide was achieved in up to 98% ee at 5 mol% loading.
Inversion of enantioselectivity in quinine-mediated desymmetrization of glutaric meso-anhydrides
作者:Trpimir Ivšić、Zdenko Hameršak
DOI:10.1016/j.tetasy.2009.02.049
日期:2009.6
An unexpected inversion of enantioselectivity, dependent on the degree Of quinine loading, was observed during the desymmetrization of glutaric meso-anhydrides. Decrease in catalyst loading from 1.6 equiv to 0.1 equiv Caused a clear inversion of stereochemistry-from about 40% ee of (R)-configuration to about 40% ee of the opposite enantiomer. The effect of various carboxylic acid additives was also studied. (C) 2009 Elsevier Ltd. All rights reserved.