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 (1)H 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 (1)H NMR spectra, thus enabling the determination of the enantiopurity of the parent diol. The protocol as described takes less than 90 min to complete.