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A versatile and simple method for aerobic oxidation of various aromatics containing an oxygen-functionalized benzylic carbon is reported. Results from oxidation experiments with methyl aryl ketones, benzaldehydes, benzylic alcohols, and mandelic acid are reported; all provide high yields of the corresponding aromatic carboxylic acids. By means of response surface methodology and mechanistic interpretation it is revealed that the oxidation process operates catalytically using electron-deficient nitroarenes, such as 1,3-dinitrobenzene, 1,2,3-trifluoro-4-nitrobenzene, and 2,4-difluoro-1-nitrobenzene, with molecular oxygen as the terminal oxidant. The reaction is carried out in a basic solution of potassium tert-butoxide in tert-butyl alcohol. Since the terminal oxidant is molecular oxygen and only 5-10 mol % of, e.g., 1,3-dinitrobenzene as catalyst is used, the new method represents an environmentally benign alternative to, for example, the well-known haloform reaction. The method is also a convincing alternative when transition metal free conditions are required.

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2005Carboxylic acids Q 0420Nitroarene-Catalyzed Oxidation with Sodium Percarbonate or Sodium Perborate as the Terminal Oxidant. -An oxidation method for the moderately efficient oxidation of aryl methyl ketones to benzoic acid is discussed. The optimized procedure shown in the scheme affords benzoic acids (II) which are of industrial interest. -(BJOERSVIK*, H.-R.; VEDIA MERINERO, J. A.; LIGUORI, L.; Tetrahedron Lett. 45 (2004) 47, 8615-8620; Dep. Chem., Univ. Bergen, N-5007 Bergen, Norway; Eng.) -Mais 08-083