Halogens halt aromatic group migration in Baeyer–Villiger oxidation

Oxidation of a dihalogenated benzaldehyde under Baeyer–Villiger conditions led to the aromatic carboxylic acid as opposed to the desired phenol. Fluorine was located at the para-position of the benzaldehyde, halting migration of the aryl group and thus resulting in the carboxylic acid product.