α,β-Unsaturated nitriles in heterocyclic synthesis: Synthesis of some new pyrazolo[1,5-a]pyrimidine derivatives

3-Antipyrinyl-5-aminopyrazole (1) reacted with acrylonitrile to afford 5-amino-1-β-cyanoethyl-3-antipyrinylpyrazole (2). Compound2 could also be obtained from the reaction of β-cyanoethylhydrazine (3) and compound4.2 was readily cyclized into 2-antipyrinyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidin-5-one (5) by acetic-hydrochloric acid.5 could be also obtained from the reaction of1 and methyl acrylate. The reaction of1 and cinnamonitrile derivatives7 a–e resulted in the formation of pyrazolo[1,5-a]pyrimidine derivatives9,11 and12.