On the reactivity of imidazole carbamates and ureas and their use as esterification and amidation reagents

The optimization, substrate scope, and mechanism of esterification and amidation of carboxylic acids mediated by imidazole-based reagents are discussed. The innate reactivity of carbonylimidazole reagents with a range of nucleophiles is also explored. New reagents developed for the synthesis of alpha,beta-unsaturated esters are described, as are reagents for the preparation of tertiary amides directly from carboxylic acids. (C) 2011 Elsevier Ltd. All rights reserved.