Synthesis of Pyrazoles and Pyrazolo[1,5-a]pyrimidines From 3-Arylsulfonylaminoacrylates

Abstract

3-Arylsulfonylaminopyrazole-4-carboxamides and -carboxylates were synthesized from 3-arylsulfonylamino-3-methylthiocyanoacrylate derivatives as potential herbicidal inhibitors of the enzyme acetohydroxyacetic acid synthase (AHAS). Some of these compounds were reacted further with acetylacetone, giving 3-arylsulfonylaminopyrazolo[1,5-a]pyrimidine-3-carboxamides by a novel route. During the synthesis of the 3-arylsulfonylaminopyrazole-4-carboxylates, the arylsulfonylamino group was observed to function as a leaving group. This phenomenon is of potential synthetic utility and was found to be sensitive to solvent and steric factors and was also observed with a methylsulfonylamino group. None of the compounds tested was biologically active.