Practical Approach for Preparation of Unsymmetric Benzils from β‑Ketoaldehydes

An efficient and practical method for the synthesis of unsymmetric benzils from readily available β-keto­aldehydes has been developed. Various unsymmetric 1,2-diaryl­diketones bearing functional groups have been obtained in good to excellent yields under mild reaction conditions. A plausible mechanism was proposed, and α,α-dichloro­ketone was considered as the key intermediate. The generation of α,α-dichloro­ketones from β-keto­aldehydes may undergo the following steps: (1) oxidation by sodium hypochlorite, (2) decarboxylation, and (3) chlorination by Cl₂ generated from sodium hypochlorite.