A molecular balance to measure the strength of N-H• • • π hydrogen bonds based on the tautomeric equilibria of C-benzylphenyl substituted NH-pyrazoles

被引：29

作者：

Cornago, Pilar ^{[1
]}

Claramunt, Rosa M. ^{[1
]}

Bouissane, Latifa ^{[1
]}

Elguero, Jose ^{[2
]}

机构：

[1] Univ Nacl Educ Distancia, Fac Ciencias, Dept Quim Organ & Bioorgan, E-28040 Madrid, Spain

[2] CSIC, Inst Quim Med, E-28006 Madrid, Spain

来源：

TETRAHEDRON | 2008年 / 64卷 / 17期

关键词：

pyrazoles; tautomerism; B3LYP/6-3 1G** calculations; hydrogen bonds;

D O I：

10.1016/j.tet.2008.02.026

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

A theoretical (B3LYP/6-31G**) study of 30 pyrazoles, most of them existing in two tautomeric forms, has been carried out. 3(5)-(2-Benzyl phenyl)-5 (3)methyl-1H-pyrazole (11) and 3 (5)-(2-benzylbenzylphenyl)-5(3)-phenyl-1H-pyrazole (20) were synthesized from 2-benzoylacetophenone, and their annular tautomeric equilibrium determined. The substituent effects were statistically analyzed and discussed with the help of Hammett substituent constants. In the case of the 5-(2-benzylphenyl) groups, the strength of the N-H center dot center dot center dot pi hydrogen bond depends on the electronic effect of the substituent at position 3. (c) 2008 Elsevier Ltd. All rights reserved.

引用

页码：3667 / 3673

页数：7

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