Concerning the structure of islandoquinone isolated from the lichen Cetraria islandica

Abstract

An investigation of the oxidative coupling products of some substituted hydroxynaphthazarins led to a revision of the proposed structure of islandoquinone, previously isolated from the lichen Cetraria islandica, and yielding (7aS*,13aS*)-6,7a-diethyl-2,5,9,11,12,13a-hexahydroxy-7,14- dioxabenzo[a]tetracene-1,4,8,13(7aH,13aH)-tetraone through X-ray diffraction analysis of its 2,11-dimethyl ether.