Formula: C5H6N2O2In 2019 ,《Annular tautomerism of 3(5)-disubstituted-1H-pyrazoles with ester and amide groups》 appeared in Molecules. The author of the article were Kusakiewicz-Dawid, Anna; Porada, Monika; Dziuk, Blazej; Siodlak, Dawid. The article conveys some information:
A series of disubstituted 1H-pyrazoles with Me (1), amino (2), and nitro (3) groups, as well as ester (a) or amide (b) groups in positions 3 and 5 was synthesized, and annular tautomerism was investigated using X-ray, theor. calculations, NMR, and FT-IR methods. The X-ray experiment in the crystal state showed for the compounds with Me (1a, 1b) and amino (2b) groups the tautomer with ester or amide groups at position 3 (tautomer 3), but for those with a nitro group (3b, 4), tautomer 5. Similar results were obtained in solution by NMR NOE experiments in CDCl3, DMSO-d6, and CD3OD solvents. However, tautomer equilibrium was observed for 2b in DMSO. The FT-IR spectra in chloroform and acetonitrile showed equilibrium, which can be ascribed to conformational changes of the cis/trans arrangement of the ester/amide group and pyrazole ring. Theor. anal. using the M06-2X/6-311++G(d,p) method (in vacuo, chloroform, acetonitrile, and water) and measurement of aromaticity (NICS) showed dependence on internal hydrogen bonds, the influence of the environment, and the effect of the substituent. These factors, pyrazole aromaticity and intra- and inter-mol. interactions, seem to have a considerable influence on the choice of tautomer. The results came from multiple reactions, including the reaction of Methyl 1H-pyrazole-3-carboxylate(cas: 15366-34-4Formula: C5H6N2O2)
Methyl 1H-pyrazole-3-carboxylate(cas: 15366-34-4) belongs to pyrazoles. Pyrazole derivatives have been reported to exhibit a wide range of applications in medicinal chemistry and pharmacology. A large number of drugs incorporating pyrazole structure have been utilized as partial agonists for nicotinic acid receptors, antidepressants, antimicrobial agents, antiviral agents, and antifungal agents solely or along with the combination of other structural motifs.Formula: C5H6N2O2
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics