Synthesis and biological activity of a new class of enaminonitrile pyrazole

Abstract

The present work illustrates the treatment of 5-amino-1,3-diphenyl-1H-pyrazole-4-carbonitrile (1) with maleic, phthalic anhydrides, acetyl chloride, and benzene sulfonyl chloride to afford the pyrazole derivatives 2-5. The treatment of pyrazole derivative 1 with some active methylene reagents namely: malononitrile, cyanoacetamide, ethyl acetoacetate afforded the pyrazolopyridine 6-9. Reaction of compound 1 with acetic anhydride gave the pyrazolopyrimidinone 10, which was allowed to react with P2S5 and POCl3 to give the thione 11 and the chloro 12 derivatives. The reaction of compounds 11 and 12 with thiosemicarbazide under different conditions gave 13 and 14. Compound 12 when reacted with hydrazine hydrate and p-toluidine gave compounds 15 and 16. The reaction of compound 10 with ethyl chloroacetate gave compound 17 which was allowed to react with thiosemicarbazide to give 22 and also to consecutive reactions with hydrazine hydrate, carbon disulfide, piperidine, hydrazine hydrate to give compounds 18-21. Finally, compound 1 was reacted with chloroacetic acid, hydrated hydrazine, urea, thiourea, benzaldehyde and triethylamine to give compounds 23-29. The newly prepared compounds were characterized by using IR, 13C-NMR, 1H-NMR, and mass spectral data. Some new pyrazole derivatives showed highly antibacterial activities.