作者:Lodovico Lunazzi、Michele Mancinelli、Andrea Mazzanti、Marco Pierini
DOI:10.1021/jo101261k
日期:2010.9.3
display restricted rotation about the Ar−C4 bond, giving rise to conformational or configurational enantiomers (atropisomers) when such a restricted motion leads to a C1 symmetry. The dynamics of the stereomutation processes of these axial enantiomers was monitored by dynamic NMR, dynamic enantioselective HPLC, or racemization kinetics, depending on the activation energies involved. These results were further
在位置4处被芳基取代的香豆素显示出绕Ar-C4键旋转受限,当这种受限运动导致C 1对称时,会生成构象或构型对映异构体(阻转异构体)。这些轴向对映异构体的立体变异过程的动力学通过动态NMR,动态对映选择性HPLC或外消旋动力学进行监测,具体取决于所涉及的活化能。DFT计算进一步支持了这些结果。在两种情况下,对映体的寿命足够长,可以在环境温度下物理分离,通过对其电子圆二向色谱光谱(ECD)的理论模拟来确定其绝对构型。