Activated nitriles in heterocyclic synthesis. A novel synthesis of pyrazolo[1,5‐a]pyrimidines and pyrano[2,3‐c]pyrazoles

Several new pyrazolo[1,5‐a]pyrimidines and pyrano[2,3‐c]pyrazoles were synthesized viathe reaction of the cinnamonitrile derivatives 1a‐c with 5‐amino‐3‐phenylpyrazole (1), 3‐amino‐2‐pyrazolin‐5‐one (2) and 3‐amino‐1‐phenyl‐2‐pyrazolin‐5‐one (22).