Simple protocols for NMR analysis of the enantiomeric purity of chiral primary amines

A simple three-component chiral derivatization protocol for determining the enantiopurity of chiral primary amines by H-1 NMR spectroscopic analysis is described here. The method involves condensation of the amines with 2-formylphenylboronic acid and enantiopure 1,1'-bi-2-naphthol. This approach affords a mixture of diastereoisomeric iminoboronate esters whose ratio can be determined by the integration of well-resolved diastereotopic resonances in their H-1 NMR spectra, thus enabling the enantiopurity of the parent amine to be determined easily. The protocol, as described, takes less than 90 min to complete.