Cyclisation reactions involving the oxidation of carboxylic acids with lead tetra-acetate. Part IV. The oxidation of o-benzoyl- and o-benzyl-benzoic acids

Abstract

Oxidation of o-benzoylbenzoic acid with lead tetra-acetate in benzene solution under nitrogen affords benzophenone, o-phenylbenzophenone, and fluorenone as major products. Their formation is readily explicable by the the formation of o-benzoylphenyl radicals. The decomposition of intermediate lead (IV) salts by way of a concerted cyclic mechanism is suggested for the formation of 3-phenylphthalide as the sole product of the oxidation of o-benzylbenzoic acid.