Cyclization of N1(1-Anthmquinonyl)-N2-phenylthiourea into thiazole derivatives
N1-(1-Anthraquinonyl)-N2-phenylthiourea, obtained from the reaction of 1-amino-anthraquinone with phenyl isothiocyanate, cyclizes in an alkaline medium into 2-3-dihydro-2-phenylimino-1H-anthra[1,2-d]thiazole-6,11-dione. Treatment of anthraquinonylthiourea with bromine in chloroform results in the formation of 1-(2-benzothiazolyl)aminoanthraquinone together with a small amount of anthrathiazole.