Chromium-pillared clay as a catalyst for benzylic oxidation and oxidative deprotection of benzyl ethers and benzylamines: a simple and convenient procedure

Abstract

A mild and efficient method for benzylic oxidation of arylmethylenes to the corresponding carbonyl compounds in good yields is described using a catalytic amount of chromium-pillard montmorillonite and equimolar quantitities of tert-butyl hydroperoxide. The method is very selective toward monocarbonyl compounds of the substrates prone to form dicarbonyl compounds. The present heterogeneous catalyst is inert toward the branched hydrocarbons and has been put to practice to obtain p-isobutylacetophenone selectively from p-isobutylethylbenzene. Furthur, the method is extended successfully to the oxidative debenzylation reactions for the first time. A striking feature of the oxidative deprotection with the present method is the deprotection of a benzyl group from the substrates having an alkyne moiety.