o-Quinonoid compounds. Part VII. 1,4-Diphenyl-2,3-naphthoquinone

Abstract

Oxidation of 1,4-diphenylnaphthalene-2,3-diol by addition of lead tetra-acetate results in a novel oxidative trimerisation. This probably proceeds through 1,4-diphenyl-2,3-naphthoquinone (1; R = Ph), for low-temperature oxidation by addition of the catechol to lead tetra-acetate in the presence of a variety of traps gives adducts of the expected type. Inhibition of endo-addition by non-planar phenyl substituents may account for the predominant formation of exo-adducts in the trapping experiments. The quinone (1; R = Ph) appears to be a more reactive oxidising agent than ortho-chloranil.