Oxidative Esterification of Benzaldehyde and Deactivated Aromatic Aldehydes with N-Bromosuccinimide-pyridine

Whereas the oxidative esterification of benzaldehyde to methyl benzoate with N-bromosuccinimide (NBS)-pyridine requires dark conditions and 5 equivalents each of NBS and K₂CO₃ and gave only moderate yield (52%) of the product (McDonald et al. J. Org. Chem. 1989, 54, 1213), simple change of base to pyridine gave the desired product in 83% gas chromatographic yield with only 1 equivalent each of NBS and pyridine. Moreover, the reaction could be conducted without exclusion of light. Aromatic aldehydes bearing electron-withdrawing substituents at meta/para position yielded the corresponding methyl esters in still better yields.

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