Iodobenzene-catalyzed α-acetoxylation of ketones.: In situ generation of hypervalent (diacyloxyiodo)benzenes using m-chloroperbenzoic acid

Reported here for the first time is the iodobenzene-catalyzed α-oxidation of ketones, in which diacyloxy(phenyl)-λ3-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid serves as a terminal oxidant. Oxidation of a ketone with m-chloroperbenzoic acid in acetic acid in the presence of a catalytic amount of iodobenzene, BF3·Et2O, and water at room temperature under argon affords an α-acetoxy ketone in good yield. p-Methyl- and p-chloroiodobenzene also serve as efficient catalysts in this direct oxidation. We found that when the reaction was carried out in the absence of a catalytic amount of iodobenzene, Baeyer-Villiger oxidation of a ketone took place. It is noted that use of water and BF3·Et2O is crucial to the success of this α-acetoxylation. Copyright © 2005 American Chemical Society.