Synthesis of 4(pyrazol‐3‐yl)[1,2,4]triazolo[4,3‐ a ]quinoxalines and tetrazolo analog

The transformation of 2‐chloro‐3‐[5‐(acetoxymethyl)‐1‐phenylpyrazol‐3‐yl]quinoxaline 3 to 1‐aryl‐4‐[5‐(hydroxymethyl‐1‐phenylpyrazol‐3‐yl][1,2,4]triazolo[4,3‐ a ]quinoxalines 4a‐c has been achieved upon treatment with aroylhydrazines in boiling butanol. Compounds 4a‐c were smoothly acetylated by acetic anhydride to give their acetyl derivatives 5a‐c in good yield. 4‐[5‐(Acetoxymethyl)‐1‐phenylpyrazol‐3‐yl]‐1‐methyl[1,2,4]triazolo[4,3‐ a ]quinoxaline was prepared by ring closure of 2‐hydrazino‐3‐[5‐(hydroxymethyl)‐1‐phenylpyrazol‐3‐yl]quinoxaline 6 by the action of acetic anhydride. The reaction of 6 with acetylacetone afforded 3‐[5‐(hydroxymethyl)‐1‐phenylpyrazol‐3‐yl]‐2‐(3,5‐dimethylpyrazol‐1‐yl)quinoxaline 8 . In addition, the reaction of 3 with sodium azide in boiling N, N ‐dimethylformamide yielded the fused tetrazolo[1,5‐ a ]quinoxaline 9 .