A novel and efficient regiospecific preparation of arenesulfonamide derivatives of 3,5-diamino-1,2,4-triazole

A new simple and efficient procedure was designed for the regiospccific preparation of arenesulfonamide derivatives of 3,5-diamino- 1,2,4-triazole 1 which are precursors of N-([ 1,2,4]triazolo [ 1,5-a] pyrimidin-2-yl)arenesulfonamides 2, an important family of herbicidal and antibacterial agents. The key feature of this procedure is the preparation of a wide range of compounds 1 on a large scale, in pure form and high yield without the need for any workup or the use of the highly hazardous hydrazine. This was made possible by a novel tandem reaction promoted by sulfuryl chloride to effect the formation of the triazole ring,