Determination of rotational barriers of c(sp2)-c(sp3) bonds in 2-arylpiperidines. II.1 1h-dnmr and 13c-dnmr studies of the trans-1,3-dimethyl-2-(3,4,5-trimethoxyphenyl)-4-piperidone
作者:Mario Rubiralta、Miguel Feliz、Carlos Jaime、Ernest Giralt
DOI:10.1016/s0040-4020(01)87550-5
日期:1986.1
1H-DNMR and 13C-DNMR has been applied to determine the rotational C(sp2)-C(sp3) barrier in hydrochloride of trans-1, 3-dimethyl-2-(3,4,5-trimethoxyphenyl)-4-piperidone () synthesized via acid catalyzed cyclization of the precursor iminoketal . 2D-NMR experiments allowed the assignment of practically all the 1H- and 13C-NMR signals. Rotational barrier around the C2-Ar bond was shown to be 55.9 KJ/mol-1
两个1 H-DNMR和13 C-DNMR已经应用到确定的旋转C(SP 2)-C(SP 3)中的盐酸盐屏障反式-1,3-二甲基-2-(3,4,5-三甲氧基)-4-哌啶酮()通过前驱体亚胺酸的酸催化环化反应合成。2D-NMR实验允许分配几乎所有的1 H-和13 C-NMR信号。以C旋转屏障2 -Ar键显示为55.9千焦/摩尔-1在20℃下通过可变温度的分析1 H-NMR谱和55.3 KJ mol的值-1使用13 C-NMR发现13 ℃的熔点。最后一个步骤也用于确定1,3,3-三甲基-2-(3,4,5-三甲氧基苯基)-4-哌啶酮()盐酸盐的旋转势垒。借助分子力学计算,根据哌啶环取代基的影响讨论了所有实验障碍。