Herein we describe a two-step conversion of aromatic methyl ketones to esters and carboxylic acids employing o-phthalaldehyde as an oxidant. In the first step, o-phthalaldehyde oxidizes the methyl group to 1-indanone, which acts as a leaving group in a subsequent regioselective retro-Claisen condensation to form esters and carboxylic acids. The mild oxidation conditions ensure the method is applicable to a broad range of substrates. Additionally, the two-step method is operationally simple and scalable, and can also be performed in a single pot.