A study of annular tautomerism, interannular conjugation, and methylation reactions of ortho-substituted-5-aryltetrazoles using carbon-13 and hydrogen-1 n.m.r. Spectroscopy
作者:Richard N. Butler、Victor C. Garvin
DOI:10.1039/p19810000390
日期:——
2′-MeC6H4, 2′-ClC6H4, or 2′,6′-Cl2C6H3), the rings are twisted out of the planar configuration and interannular conjugation is inhibited. In each case the tetrazole 1-NH tautomêr is strongly predominant. When the rings are coplanar, as in para-substituted-5-phenyltetrazoles, the electron-withdrawing effect of the para-substituents changes the tautomerism significantly back towards the 2-NH form. Methylation
在邻位取代的-5- phenyltetrazoles中,Ar - CN 4 H(Ar为2'-MEC 6 ħ 4,2'-CLC 6 ħ 4,或2',6'-CL 2 ç 6 ħ 3),所述环将其扭出平面构形,并抑制环间共轭。在每种情况下,四唑1-NH互变异构体都非常占优势。当环是共面的,如在对-取代的-5- phenyltetrazoles,所述的吸电子效应对位-取代基改变了互变异构显著向后朝向2-NH形式。5-(邻位阴离子的甲基化-取代的苯基)四唑在1-N-和2-N-位置上均等地出现,或稍微偏向1-N-位置,因此与对位-取代的衍生物形成对比,其中2- N-甲基化是主要优势。