Ebenaceae extractives. Part IV. Diosindigo A, a blue pigment from several Diospyros species

Abstract

The wood of seven of the eighteen species of Diospyros examined contains small amounts of a blue pigment, diosindigo A [8,8′-dihydroxy-4,4′-dimethoxy-6,6′-dimethyl-2,2′-binaphthylidene-1,1′-quinone(I; R¹= Me, R²= OH)]. Other extractives include plumbagin, 7-methyljuglone, isodiospyrin, mamegakinone, bergenin, lupeol, betulin, betulinic acid, oleanolic acid, β-sitosterol, and stigmasterol. Diosindigo A has been synthesised by the oxidation of 4-methoxy-6-methylnaphthalene-1,8-diol, prepared from 7-methyljuglone.