In the presence of samarium diiodide, 2-aryl and 2-heteroaryl cyclopropane-1, 1-dicarboxylic esters were readily dimerized to give 3, 4-disubstituted 1, 1, 6, 6-hexanetetracarboxylic esters as diastereomeric mixtures in moderate to good yields. The diastereomeric mixtures were separated by preparative HPLC and stereo-chemistries of the isolated meso and racemic compounds were determined on the basis of HPLC analysis on chiral stationary phases. Between the 1H-NMR spectra of the separated diastereomers, the characteristic differences in the chemical shifts of the C2-H (C5-H) signals were observed and explained based on the MOPAC calculation.
                                    在
镧系二
碘化钐的存在下,2-芳基和2-杂芳基
环丙烷-1,1-二
羧酸酯易于聚合,生成3,4-二取代的1,1,6,6-己烷四
羧酸酯,作为不同构型的混合物产率适中至良好。这些不同构型的混合物通过制备型HPLC分离,分离出的
间苯二酚和外消旋化合物的立体
化学通过在手性固定相上的HPLC分析确定。在分离的不同构型的1H-NMR光谱中,观察到C2-H(C5-H)信号
化学位移的特征差异,并基于
MOPAC计算进行了解释。