4-(4-Acethylphenyl)-3-hydroxycoumarin in the Synthesis of Nitrogen-containing Heterocycles with a Neoflavonoid Moiety

Abstract

4-(4-Acetylphenyl)-3-hydroxy-2H-chromen-2-one has been prepared by the reaction of (4-acetylbenzene)diazonium chloride with 3-hydroxy-2H-chromen-2-one under Meerwein reaction conditions. The reactions of 4-(4-bromoacetylphenyl)-3-hydroxy-2H-chromen-2-one with pyridine, 4-methylpyridine, quinolone, and benzo[f]quinoline gave quaternary salts, and the reactions of the same bromo derivative with thioacetamide, thiourea, pyridine-2-amine, pyrimidin-2-amine, and thiazol-2-amine provided corresponding thiazole, imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine, and imidazo[2,1-b]thiazole derivatives. The reactions of 4-(4-bromoacetylphenyl)-3-hydroxy-2H-chromen-2-one with thiosemicarbazide and aromatic aldehydes involve thiazole ring formation, leading finally to corresponding hydrazones. It was established that 4-(4-acetylphenyl)- and 4-[4-(2-bromoacetyl)phenyl]-3-hydroxy-2H-chromen-2-ones can be used in three-component reactions to form a thiazole ring.