Synthesis and characterization of new heterocycles containing the 1,2,3-triazole ring system

Abstract

The unexpected (E)-1,4-bis(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)but‑2-ene-1,4‑dione was produced in 89 % yield from the reaction of 2‑bromo-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one and sodium benzenesulfinate dihydrate in boiling ethanol. The reaction of the synthesized symmetrical 2-butene-1,4‑dione and 1,2-phenylenediamine in acetic acid afforded 2-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)-1H-benzo[d]imidazole in 68 % yield. 2,3-Dibromopropan-1-one was synthesized in 82 % from bromination of the corresponding chalcone under acidic conditions. Treatment of dibromoketone and benzylamine or phosphonic dihydrazide in ethanol in the presence of a basic catalyst unexpectedly afforded 2‑bromo-3-ethoxyketone in reasonable yield. The reactivity of hydrazonoyl chloride towards 5-methyl- and 5‑chloro-1,2,3-triazol-4-carbohydrazides was also investigated to afford the corresponding bis-hydrazone and the unanticipated tris-hydrazone.