NaIO4/Br- as a mild system for the oxidation of 1-methyl-anthra-9,10-quinones

One of the anthraquinone classes comprises compounds with a carbonyl group. These natural or synthetic anthraquinones find their application as building blocks in the synthesis of the compounds with a biological activity. Recently, 4-substituted anthra-9,10-quinone-1-carboxylic acids (2) have been used as key intermediates in the synthesis of patented compounds (3) with anticancer activity against multidrug resistant cell lines [1, 2]. Although 2,7-dihydro-3H-dibenz[de,h]cinnolin3,7-diones (3) were successfully synthetized in a small laboratory scale, several problems were observed during the preparation of their acid intermediates (2) in a multi-gram scale.