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.