Showing papers by "Rosa M. Claramunt published in 1985"
TL;DR: In this article, the 13C NMR data for 3-aminoindazole and 14 aminopyrazoles were obtained in neutral and acidic media (trifluoroacetic acid) and compared with those for a series of pyrazoles, aminothiophenes and anilines as models for protonation.
Abstract: The 13C NMR data for 3-aminoindazole and 14 aminopyrazoles were obtained in neutral and acidic media (trifluoroacetic acid) and compared with those for a series of pyrazoles, aminothiophenes and anilines as models for protonation. From the chemical shifts and coupling constants it is possible to conclude that all 3-aminopyrazoles, 3-aminoindazole and 5-aminopyrazoles protonate on the heterocyclic ring nitrogen atom. This first protonation strongly deactivates the exocyclic nitrogen atom, so that no double protonation is observed, even in sulphuric acid. On the other hand, 4-aminopyrazoles are stronger bases, which are protonated first at the amino group and then on both nitrogen atoms.
27 citations
TL;DR: The pKa values of five aminopyrazoles [3(5)-amino, 1-methyl-3-amino and 4amino were determined in terms of tautomerism, protonation site and amino substituent effects.
21 citations
TL;DR: In this paper, 1,1'-diindazolylphenylmethanes have been prepared from indazoles and benzaldehyde in presence of zinc chloride as catalyst, which is strongly dependent on the basic pK a's of azoles and only few pyrazolyl derivatives could be prepared by this procedure.
19 citations
18 citations
Journal Article•
TL;DR: Les azoles etudies sont les composes suivants: derives du 1Hpyrazole, 1H-imidazole,1H- and 4H-triazoles-1,2,4 as mentioned in this paper.
10 citations
9 citations
TL;DR: Les azoles etudies sont les composes suivants: derives du 1Hpyrazole, 1H-imidazole,1H- and 4H-triazoles-1,2,4 as mentioned in this paper.
Abstract: Les azoles etudies sont les composes suivants: derives du 1H-pyrazole, 1H-imidazole, 1H- et 4H-triazoles-1,2,4, 1H- et 2H-tetrazoles, 1H-benzimidazole, 1H- et 2H-indazoles et 1H- et 2H-benzotriazoles
8 citations
1 citations