Determination of Enantiomeric Excess in Amine Derivatives with Molecular Self-Assemblies

We report the first fluorescence‐based assay for the rapid determination of the ee value of amines, amino alcohols, and amino acid esters. The method uses the self‐assembly of 2‐formylphenylboronic acid with a chiral diol and a chiral amine or derivatives (of unknown chirality) to produce two diastereomeric iminoboronates that differ in their fluorescence intensity and polarization. The approach allows for the accurate determination of the ee value of chiral amines with errors of just 1–2 %. We believe that this application of orthogonal dynamic covalent self‐assembly in the determination of the enantioselectivity will lead to the development of high‐throughput procedures for the determination of chirality. The dynamic covalent self‐assembly of chiral amines with chiral fluorescent diols and 2‐formylphenylboronic acid produces fluorescent diastereomeric iminoboronates that differ in their fluorescence intensity and polarization. This fluorescence‐based assay for the rapid determination of the enantiomeric excess of amine derivatives requires only simple laboratory instrumentation and is amenable to high‐throughput screening.