1988
DOI: 10.1002/mrc.1260260210
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Effect of N‐substituents on the 13C NMR parameters of azoles

Abstract: The I3C chemical shifts and a large collection of coupling constants have been measured for 169 N-substituted azoles with no other substituents on the ring. Simple additive models have been used to discuss both the chemical shifts and the coupling constants. The chemical shift of the substituent depends on the nature of the azole which can, accordingly, be classified into three to six families. Some structural problems (ringchain isomerism of 1-trifluoromethylsulphonyl-1,2,3-triazole, silylotropy and stannotro… Show more

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Cited by 157 publications
(77 citation statements)
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“…Therefore, both tautomers were identified without ambiguity by 13 C NMR and, through 2D correlations, the same is true for 1 H NMR. Finally, in HMPT-d 18 at room temperature, only N-14 was observed at υ 15 N D 72.1 ppm; the benzimidazole nitrogens were not observed owing to the broadening produced by the tautomerism.…”
Section: Theoretical Calculationsmentioning
confidence: 89%
See 1 more Smart Citation
“…Therefore, both tautomers were identified without ambiguity by 13 C NMR and, through 2D correlations, the same is true for 1 H NMR. Finally, in HMPT-d 18 at room temperature, only N-14 was observed at υ 15 N D 72.1 ppm; the benzimidazole nitrogens were not observed owing to the broadening produced by the tautomerism.…”
Section: Theoretical Calculationsmentioning
confidence: 89%
“…17 Almost all signals were assigned and are consistent with 13 C NMR data for benzimidazoles. 18 Some signals of the N-methyl derivatives are only tentatively assigned when they are too close (the subscript figures in Table 1 are necessary to distinguish some pairs of signals). The absolute shieldings were calculated at the GIAO/B3LYP/6-311CCG ŁŁ level.…”
Section: Methodsmentioning
confidence: 99%
“…A key requirement was the unambiguous assignment of the signal sets of the two phenolic ring systems (C-12-17 versus C-18 -23) attached to C-3 and C-5 of the triazole ring, respectively. According to Begtrup et al (1988) and Schleucher et al (1994), the 13 C NMR shifts of the C-3 atom in N-1-substituted 1,2,4-triazoles are shifted to low field compared with the shift of the C-5 atom. Thus, in a heteronuclear multiple bond correlation (HMBC) experiment, the H-17 signal at 8.04 ppm (see Table 5 and Fig.…”
Section: Bruin Et Almentioning
confidence: 99%
“…C NMR signals of imidazoles 2-5 of Table 1 is straightforwarded by comparison with compounds 6-9 and references [30][31][32]. All the signals are Compound average and narrow indicating rapid N 1 -H/N 3 -H tautomerism.…”
mentioning
confidence: 93%
“…N NMR spectroscopy of azoles have also been used for assignment purposes [30][31][32]. Table 1 The assignment of the…”
mentioning
confidence: 99%