POLYCYCLIC HYDROXYQUINONES - VIII. PREPARATION OF ACETYLHYDROXYNAPHTHAZARINS BY PHOTO-FRIES REARRANGEMENT. A CONVENIENT SYNTHESIS OF SPINOCHROME A

Article abstract of DOI:10.1016/0040-4020(82)80244-5

Several synthetic routes to mono- and dihydronaphthazarins bearing an acetyl side-chain have been explored.Methoxynaphthazarin 1 has always been the starting material.Acylation is brought about via a photo-Fries rearrangement of various adequately substituted acetoxynaphthalenes prepared in several steps from 1.Further steps including oxidative demethylation, hydrolysis and ether cleavage reactions, led to the desired mono- and dihydroxysubstituted acetylnaphthazarins.A new synthesis of Spinochrome A 24, a natural occuring pigment representative of this kind of naphthazarin derivatives, is described.