Formation of polycyclic quinones in oxidations of 3,3′,4,4′-tetramethoxybiphenyl and veratrole

Abstract

The oxidation of 3,3′,4,4′-tetramethoxybiphenyl by chloranil in 70% v/v aqueous sulphuric acid gives 2,5,6,9,12,13-hexamethoxydibenzo[fg,op]naphthacene-1,8-quinone (III) in 75% yield while the isomeric 1,10-quinone (IV) is formed in 7% yield during the oxidation of veratrole under similar conditions.