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

Beilstein Journal of Organic Chemistry

M. Ángeles García¹  Carla I. Nieto¹  Rosa M. Claramunt¹  Pilar Cabildo¹  Ibon Alkorta²  José Elguero² 

[1] Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED Senda del Rey 9, E-28040 Madrid, Spain;Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain;

关键词: CPMAS;    DNMR;    GIAO;    proton transfer;    tautomerism;   

DOI  :  10.3762/bjoc.10.168

来源: DOAJ

【 摘 要 】

This paper reports the 1H, 13C and 15N NMR experimental study of five benzimidazoles in solution and in the solid state (13C and 15N 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-d18.

【 授权许可】

Unknown