Inversion of enantioselectivity in quinine-mediated desymmetrization of glutaric meso-anhydrides

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.