Studies in the xanthone series. Part VIII. An unambiguous synthesis of jacareubin

Abstract

An unambiguous synthesis of jacareubin has been effected by following a plausible biogenetic route. Phenol oxidative coupling of maclurin gave 1,3,6,7-tetrahydroxyxanthone but 1,3,5,6-tetrahydroxyxanthone was obtained by a more conventional method. Introduction of a 3,3-dimethylallyl side-chain into the 2-position of 1-hydroxy-3,5,6-trimethoxyxanthone, followed by methylation and treatment with hydriodic acid, gave dihydro-jacareubin which was dehydrogenated to yield jacareubin.