Decarboxylative/Oxidative Amidation of Aryl α‑Ketocarboxylic Acids with Nitroarenes and Nitroso Compounds in Aqueous Medium

The
decarboxylative/oxidative amidation of aryl α-ketocarboxylic
acids with 5-aryl-3-nitroisoxazole-4-carboxylates and substituted
dinitrobenzenes under oxidative aqueous conditions to afford N-aryl amides is described. The reaction is suggested to
proceed via a radical pathway in which a benzoyl nitroxyl radical,
the key intermediate formed from reaction between nitroarene and benzoyl
radical from glyoxalic acid, couples with hydroxyl radical from water
to produce amide. Mechanistic insight allowed the scope of the strategy
to be expanded to the synthesis of amides via reaction between aryl
α-ketocarboxylic acids and nitroso compounds.