Dakin-West synthesis of beta-aryl ketones.

Triethylamine and 1-methylimidazole were found to be selective catalysts for the Dakin-West synthesis of diaryl ketones and aryl methyl ketones, respectively. In the 1-methylimidazole-catalyzed reaction, catalysis is due to the simultaneous formation of both an effective acylating agent, 1-acyl-3-methylimidazolium, and a base, carboxylate anion. Hydrocinnamic acid, a compound previously reported to be unreactive under Dakin-West conditions, forms 4-phenyl-2-butanone when the reaction is catalyzed by 1-methylimidazole.