One-step, facile synthesis of pyrazolopyridines and tetrahydropyrazolopyridines through disproportionation of initially formed pyrazolo Hantzsch dihydropyridine

Abstract

We have developed a single-step synthesis of pyrazolopyridines and hydropyrazolopyridines by condensation 3-carbonitrile-5-aminopyrazole (1) with seven substituted α, β-unsaturated aldehydes in acid medium. Straightforward access to various pyrazolopyridines and hydropyrazolopyridines was achieved through disproportionation of initially formed pyrazolo Hantzsch dihydropyridines. All the pyrazolopyridines and hydropyrazolopyridines were well characterized by spectroscopic analyses.