Synthesis of 1-substituted and 1-unsubstituted 4-sulfonamido-1H-pyrazol-5(2H)-ones

Article abstract of DOI:10.1055/s-1996-4231

4-Sulfonamido-1H-pyrazol-5(2H)-ones bearing different substituent groups on the nitrogen atom in position 1 were easily obtained by reaction of conjugated azoalkenes with sulfonamides under mild conditions. 1-Unsubstituted title compounds were smoothly obtained by solvolytic cleavage of the substituent groups in methanol under reflux.