Selective oxidation of aromatic aldehydes to arenecarboxylic acids using ebselen-tert-butyl hydroperoxide catalytic system

It has been found that aromatic aldehydes with electron-withdrawing as well as electron-donating substituents are oxidized to arenecarboxylic acids using tert-butyl hydroperoxide in the presence of ebselen (2-phenylbenzisoselenazol-3(2H)-one) as a catalyst. The reaction is highly chemoselective and formation of phenols, being the products of competitive Baeyer-Villiger rearrangement, is marginal. It has been assumed that this rearrangement is inhibited by steric hindrance of the electron-deficient oxygen atom in the transient tetrahedral intermediate. (C) 2001 Elsevier Science Ltd. All rights reserved.