Efficient synthesis of some new functionalized 3-amino- and 5-aminopyrazoles derivatives

Abstract

Cyanoacetic acid hydrazide derivatives were utilized as key intermediates for the synthesis of some new 3-amino- and 5-aminopyrazole derivatives. Coupling of N′-phenylsulfonyl-2-cyanoacetohydrazide (1) and 1-(2-cyanoacetyl)-4-phenyl thiosemicarbazide (4) with different aryl diazonium chlorides afforded the corresponding 5-amino-1-substituted-4-pyrazolin-3-one derivatives 3 and 6, respectively. Treatment of ketene dithioacetal 9 and ketene-N,S-acetal 13 with hydrazine and/or benzenesulfonyl hydrazide furnished the corresponding 3-amino-5-1H-pyrazole-4-carbohydrazide derivatives 10, 11, and 14. The structures of the new synthesized compounds were elucidated and confirmed by elemental analyses and spectral data.