Simple Chiral Derivatization Protocols for ¹H NMR and ¹⁹F NMR Spectroscopic Analysis of the Enantiopurity of Chiral Diols

Two practically simple chiral derivatization protocols for determining the enantiopurity of chiral diols by ¹H NMR and ¹⁹F NMR spectroscopic analysis are described, involving treatment of the diol with 2-formylphenylboronic acid and α-methyl-4-fluorobenzylamine, or its derivatization with 4-fluoro-2-formylphenylboronic acid and α-methyl-benzylamine. Both approaches afford mixtures of imino−boronate esters whose diastereomeric ratio may be measured by ¹H NMR or ¹⁹F NMR spectroscopy, the value of which is an accurate reflection of the enantiopurity of the parent diol.