Reisberg P, Brenner I A, Bodin J I
J Pharm Sci. 1976 Apr;65(4):592-4. doi: 10.1002/jps.2600650428.
A simple NMR method was developed for the determination of the enantiomers of 7-chloro-3,3a-dihydro-2-methyl-2H,9H-isoxazolo[3,2-b][1,3]benzoxazin-9-one. Chiral shift reagent, tris[3-(heptafluoroburyryl)-d-camphorato]europium(III), causes the doublet assigned to the protons of the 2-methyl group, which normally appears at about 1.5 ppm, to split into two pairs of doublets and to shift downfield to about 2.0-3.5 ppm. The downfield pair of doublets represents the two enantiomers present in one racemate, designated as the beta-form, while the upfield pair represents the enantiomers of the racemate designated as the alpha-form. From the integration of the area under the doublets, the relative concentration of all four enantiomers was determined.
开发了一种简单的核磁共振方法用于测定7-氯-3,3a-二氢-2-甲基-2H,9H-异恶唑并[3,2-b][1,3]苯并恶嗪-9-酮的对映体。手性位移试剂三[3-(七氟丁酰基)-d-樟脑酸根合]铕(III)使通常出现在约1.5 ppm处的归属于2-甲基质子的双峰分裂为两对双峰，并向下场位移至约2.0 - 3.5 ppm。下场的一对双峰代表一种外消旋体中存在的两种对映体，称为β-型，而上场的一对双峰代表称为α-型的外消旋体的对映体。通过对双峰下面积的积分，确定了所有四种对映体的相对浓度。
