Hassall Kathryn, Lobachevsky Sofia, White Jonathan M
School of Chemistry, The University of Melbourne, Parkville VIC 3010, Melbourne, Australia.
J Org Chem. 2005 Mar 18;70(6):1993-7. doi: 10.1021/jo048384p.
[structure: see text] N-Methyl-2-trialkylsilylmethylpyridinium cations 6a-c and 4-trialkylsilylmethylpyridinium cations 5a-c were prepared and investigated using (29)Si and (13)C NMR and single-crystal X-ray crystallography. Systematic differences in the (29)Si chemical shifts and (29)Si-(13)C one-bond coupling constants for these cations suggested that the Si-CH(2) bond interacts more strongly at the 2-position of the electron-deficient pyridinium ring than at the 4-position. This result is supported by the X-ray structures of the pyridinium cations 5b and 6b.
[结构：见正文] 制备了N-甲基-2-三烷基硅基甲基吡啶鎓阳离子6a - c和4-三烷基硅基甲基吡啶鎓阳离子5a - c，并使用(29)Si和(13)C核磁共振以及单晶X射线晶体学进行了研究。这些阳离子的(29)Si化学位移和(29)Si-(13)C一键耦合常数的系统差异表明，Si-CH(2)键在缺电子吡啶鎓环的2位比在4位的相互作用更强。吡啶鎓阳离子5b和6b的X射线结构支持了这一结果。
