Regioselective synthesis and computational calculation studies of some new pyrazolyl‐pyridine and bipyridine derivatives

Abstract

Starting from 3‐oxo‐ N‐(3‐pyridyl)butanamide, as key intermediate, the title compounds were synthesized in good yields. Reaction of the pyridine‐carboxamide 1 with hydrazonoyl chlorides 3a,b and with triethyl orthoformate afforded the corresponding pyrazole‐carboxamides 6a,b, and the bis‐pyridine 7, respectively. Coupling of the pyridine‐carboxamide 1 with 3‐phenylpyrazole‐5‐diazonium chloride gave the hydrazone 10 which upon heating in pyridine afforded the pyrazolo[5,1‐c]‐1,2,4‐triazine derivative 11. Reaction of the pyridine‐carboxamide 1 with arylmethylenepropanedinitrile derivatives afforded 1,3′‐bipyridines 13a–c. Structure elucidation of the newly synthesized compounds was carried out using IR, NMR spectroscopy, and mass spectrometry. The extensive theoretical and experimental mechanical studies of the pyrazole derivative 6a were in accordance with its elemental analysis, FT‐IR, NMR, and MS spectral data. Moreover, computer analyses indicated that the pyridine derivatives 13a,b predominated over the pyran derivatives 14a,b as the adducts. In addition, the optimization of compounds utilized the HF/6‐31G(d) and DFT/B3LYP/6‐31G(d) basis sets. Furthermore, the physical descriptors of these compounds demonstrated their stability, and NMR correlation investigations were also carried out.