Studies on aminopyrazoles: antibacterial activity of some novel pyrazol.

Hydrazones 2a-d were prepared from diazotiazation of sulfanilamide or its derivatives followed by coupling with ethyl cyanoacetate. 3-Aminopyrazoles 3a-d were obtained by refluxing of 2a-d with hydrazine hydrate in ethanol. [Bis(-methylthio)methylene]malononitrile (4) was reacted with aminopyrazoles 3a-d in refluxing DMF containing triethylamine to yield the novel pyrazolo[1,5-a]pyrimidines 6a-d. The anilino derivatives 8a-h were obtained by fusion of compounds 6a-d with aromatic amines. When compounds 6a,c,d were subjected to the reaction with hydrazine hydrate, the hydrazino derivatives 9a-c were isolated. Also, the aminopyrazoles 3 were reacted with some electrophiles such as arylidenemalononitriles, ethoxymethylene malononitrile and ethyl ethoxymethylene cyanoacetate to yield the novel substituted pyrazolo[1,5-a]pyrimidines 13, 17 and 19, respectively. Structures of the new compounds were established by their elemental analyses and spectral data. Most of these compounds were also tested in vitro for their antibacterial activity against some gram positive and gram negative bacteria.