Heteroanthracyclines. 2. 4-Demethoxythioxanthodaunomycinone (7,8,9,10-tetrahydrobenzo(b)-6,7,9,11-tetrahydroxy-9-acetylthioxanthen-12-one)

Abstract
The title compound, a new heteroanthracyclinone was synthesized in five steps starting with 5,8-dimethoxy-2-acetyltetralin (15). Reaction of 2,2′-dithiosalicylic acid (16) with the tetralin 15 in concentrated sulfuric acid gave the tetracyclic thioxanthones 17 and 18. Conversion of 18 to 24 by demethylation and realkylation followed by oxidation and acid hydrolysis gave the title compound 27.