An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

被引:43
|
作者
Nieto, Carla I. [1 ]
Cabildo, Pilar [1 ]
Angeles Garcia, M. [1 ]
Claramunt, Rosa M. [1 ]
Alkorta, Ibon [2 ]
Elguero, Jose [2 ]
机构
[1] Fac Ciencias, Dept Quim Organ & Bioorgan, E-28040 Madrid, Spain
[2] CSIC, Inst Quim Med, E-28006 Madrid, Spain
来源
关键词
CPMAS; DNMR; GIAO; proton transfer; tautomerism; MULTINUCLEAR MAGNETIC-RESONANCE; MOLECULAR-ORBITAL METHODS; HETEROCYCLIC SERIES; CROSS-POLARIZATION; CHEMICAL-SHIFT; C-13; N-15; SPECTROSCOPY; BENZAZOLES; OMEPRAZOLE;
D O I
10.3762/bjoc.10.168
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
This paper reports the H-1, C-13 and N-15 NMR experimental study of five benzimidazoles in solution and in the solid state (C-13 and N-15 CPMAS NMR) as well as the theoretically calculated (GIAO/DFT) chemical shifts. We have assigned unambiguously the "tautomeric positions" (C3a/C7a, C4/C7 and C5/C6) of NH-benzimidazoles that, in some solvents and in the solid state, appear different (blocked tautomerism). In the case of 1H-benzimidazole itself we have measured the prototropic rate in HMPA-d(18).
引用
收藏
页码:1620 / 1629
页数:10
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