H-NMR—位移试剂法研究α-氨基酸及α-取代胺的构型和对映体含量

DETERMINATION OF ENANTIOMERIC EXCESS AND CONFIGURATIONOF α-AMINO ACIDS AND α-SUBSTITUTED BENZYLAMINES BY ~1H-NMR

本文报道了在研究α—氨基酸及α—取代苄胺的不对称合成中,用核磁共振波谱法和手性位移试剂—Eu（hfc）3给出′H—NMR谱。利用OCH3基团的明显单蜂,在加入以上位移试剂后,单峰向低场位移,分别在5和7ppm左右分裂成二个峰,其积分值可计算e.e值。由于Eu（hfc）3为R构型,它同被测样品分别生成R—R,R—s构型的络合物,前者的位移较后者快,从而可确定样品的R和s构型的位置。

A simple and accurate method is described for the determination of enantiomeric excess (e.e.%) and configuration of α-amino acids, and α-substituted benzylamines by ~1H-NMR, using Eu(hfc)_3 as shift reagent and CDCI_3 as solvent. At the molar ratios (r/s) of the shift reagent (r) to substrate (e) being 0.09 for α-amino acids and 1.38 for α-substituted benzylamines, the splits of methoxy-~1H signal for the two enantiomers were obviously observed at 7 and 5 ppm respectively. Therefore, the e.e. values and configurations could be determined by the comparison of the Integrals of the two signals.