Synthesis of Some New 3-(5-(Arylamino)-1,3,4-thiadiazol-2-yl)-2H-chromen-2-ones and 3-(4-Aryl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-YL)-2H-chromen-2-ones

Abstract

In this study, 2-oxo-2H-chromene-3-carbohydrazide (1) was synthesized by the condensation of ethyl 2-oxo-2H-chromene-3-carboxylate with hydrazine hydrate. Thiosemicarbazide derivatives (3a–g) were afforded by the treatment of carbohydrazide (1) with substituted phenyl isothiocyanates (2a–g). The cyclization of compounds (3a–g) in the presence of aqueous sodium hydroxide resulted in the formation of compounds 4a–g containing a 1,2,4-triazole ring. On the other hand, the treatment of compounds 3a–g with polyphosphoric acid caused the conversion of side chain of 3a–g into the 1,3,4-thiadiazole ring; thus, compounds 5a–g were obtained. The structures of the products were established by elemental analyses, IR, 1H, and 13C NMR spectroscopy. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT