New pyrazolo[1,5-a]pyrimidine-3-carbonitrile 5 was obtained by reaction of 5-amino-3-cyanomethyl-1H-pyrazole-4-carbonitrile 3 with enamine of acetylacetone 2. Coupling of compound 5 with aryldiazonium chloride 6a-c afforded pyrimido[1',2':1,5]pyrazolo[3,4-d]pyridazine derivatives 8. Also, condensation of compound 5 with aromatic aldehydes 9a-c gives the corresponding arylidene derivatives 10. stirring of compound 5 with phenyl isothiocyanate in presence of potassium hydroxide, followed by addition of phencyl bromide derivatives 13a-c or chloroacetonitrile 18 afforded (thiophen-3-yl)-7-methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile 16a-c and 20 which cyclized by refluxing in ethanolic sodium ethoxide solution to afforded thieno[3'',4'':5',6']pyrido [4',3':3,4]pyrazolo[1,5-a]pyrimidine derivatives 17a-c and 21.