Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone—the more polar the molecule the more stable the axial conformer
作者:Erich Kleinpeter、Matthias Heydenreich、Andreas Koch、Torsten Linker
DOI:10.1016/j.tet.2012.01.022
日期:2012.3
synthesized and the conformational equilibria studied by 1H and 13C NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial/equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the
4-羟基-环己酮和酯一系列羧酸R-COOH与不同的电子和空间影响(R =甲基,乙基认为R Ñ -Pr,我-Pr,Ñ -Bu,我-Bu,仲-合成了Bu,t- Bu,CF 3,CH 2 Cl,CHCl 2,CCl 3,CH 2 Br,CHBr 2和CBr 3),并通过1 H和13 C NMR光谱研究了在103 K和30 ℃下的构象平衡。分别为295K。轴向/轴向优化结构的几何形状赤道主持人遵循者是从理论上从头开始计算MO和DFT的。对于轴向和赤道构象物也仅获得一种优选的构象。当将环己酮酯的构象平衡与相应的环己基酯的构象平衡进行比较时,表明环己酮骨架的一定极性贡献,这与取代基效应无关,并且以恒定量增加了轴向构象异构体的稳定性。