Nitriles in heterocyclic synthesis: Synthesis of pyrazolo[1, 5-a] pyrimidine,pyrazolo[1, 5-c][1, 2, 4]triazine and pyrazolo[4, 3-e][1, 2, 4]triazine derivatives

5-Amino-3-phenylpyrazole ( 1 ) reacted with enaminonitriles 2a – c to afford the pyrazolopyrimidines 5a , b and the 5-substituted aminopyrazole 8 . 5a reacted with arenediazonium chlorides and benzaldehyde to give 6 and 7 respectively. Also, o-hydroxyacetophenone afforded the fused pyrazole derivative 9 on treatment with 1 . Enaminonitrile 3 coupled with 11 and arenediazonium chlorides to give 12 and 13 respectively. Cyclization of 13a , b afforded the pyrazolotriazines 15a , b .