One-step synthesis of 1-chloro-3-arylacetone derivatives from arylacetic acids.

A practical one-step method has been developed to prepare alpha-chloroketones from readily available, inexpensive phenylacetic acid derivatives. The method utilizes the unique reactivity of an intermediate Mg-enolate dianion, which displays selectivity for the carbonyl carbon of chloromethyl carbonyl electrophiles. Decarboxylation of the intermediate occurs spontaneously during the reaction quench. The utility of the reaction products has been demonstrated through the total synthesis of the natural product cimiracemate B.