Simple protocols for NMR analysis of the enantiomeric purity of chiral diols

A three-component chiral derivatization protocol for determining the enantiopurity of chiral diols by H-1 NMR spectroscopic analysis is described here. The present approach involves the derivatization of 1,2-1,3- and 1,4-diols with 2-formylphenylboronic acid and enantiopure alpha-methylbenzylamine. This method affords a mixture of diastereoisomeric iminoboronate esters whose ratio can be determined by integration of well-resolved diastereotopic resonances in their H-1 NMR spectra, thus enabling the determination of the enantiopurity of the parent diol. The protocol as described takes less than 90 min to complete.