Light-induced decarboxylation of (o-acylphenyl)acetic acids

Near-UV irradiation of both o-acetylphenyl- and o-benzoylphenylacetic acids in benzene solution results in their efficient decarboxylation. Their meta and para isomers do not undergo this process. The O-deuterated acids yield deuterated o-acyltoluene products, suggesting the possibility of an intramolecular proton transfer step in the decarboxylation process, although intermolecular deuteration would achieve the same result. The corresponding esters and amides are essentially photoinert and, like the acids, do not undergo the benzocyclobutenol formation expected of o-alkylphenyl ketones.