Synthesis and some reactions of 4-hydroxy-2-methoxycarbonylquinoline-5,8-quinone

Abstract

The title quinone was prepared by oxidation of 5,8-dihydroxy-2-methoxycarbonyl-4(1H)-quinolone with cerium(IV) ammonium nitrate. Addition of hydrogen chloride, toluene-p-sulphinic acid, and hydrazoic acid to the quinone yielded the corresponding 6-substituted hydroquinones. Attempted Diels–Alder addition of cyclohexa-1,3-diene to the quinone gave a low yield of the expected adduct but 1,3-dimethoxycyclohexa-1,3-diene gave a product tentatively formulated as a derivative of benzofuro[3,2-h]quinoline.