Exploration of lipase-catalyzed direct amidation of free carboxylic acids with ammonia in organic solvents

Lipase-catalyzed direct amidation of free carboxylic acids is possible with ammonia in organic solvents. For butyric acid as a model compound the reac tion proceeds well despite precipitation of ammonium butyrate, provided tha t the added molar amounts of butyric acid and ammonia are in the same range . The addition of ammonium salts is a convenient way to ensure suitable amm onia concentrations, Using Candida antarctica lipase B as the biocatalyst, the amidation proceeds well for various carboxylic acids and is very enanti oselective in the amidation of 4-methyloctanoic acid. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.