Activated nitriles in heterocyclic synthesis: synthesis of substituted pyrazolopyridine, pyridine, 4H-pyran and naphthodiapyran derivatives

Several new pyrazolopyridines VIa-c were synthesized by reacting 4-nitrosoantipyrine [IIa] with arylidenemalononitriles Ia-c or ethyl arylidenecyanoacetates If-h. Reaction of Ia-c with 4-[azidomethylcarbonyl] antipyrine [IIb] afforded the pyridine derivatives XVI. The 4H-pyrans and naphthodipyran derivatives XVIII- XXI were prepared by reacting I with polyhydric phenols