Determination of the absolute stereochemistry of alcohols and amines by NMR of the group directly linked to the chiral derivatizing reagent

NMR experiments and calculations (PM3) indicate that the asymmetry of the substrate (alcohol or amine) leads to the redistribution of the conformer populations of their methoxyphenylacetic acid (MPA) or methoxytrifluoromethylphenylacetic acid (MTPA) derivatives rather than to the distortion of the conformer geometry as was postulated by Mosher. An absolute configuration of secondary alcohols and primary amines can be determined according to the chemical shifts of the CαH protons in NMR spectra of their MPA derivatives. The CαH proton of the diastereomer having a greater relative population of the sp form should resonate at a lower field. © 2001 Elsevier Science Ltd