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.

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GRAPHICAL ABSTRACT

Keywords:

• Coumarin
• 1
• 3
• 4-thiadiazole
• thiosemicarbazides
• 1
• 2
• 4-triazole

Acknowledgments

A.I. is thankful for a research scholarship from HEC Islamabad under HEC Indigenous PhD Scholarship 5000 Scheme.

Notes

R_f solvent system (petroleum ether:ethyl acetate, 4:1).