Simple and efficient methods for discrimination of chiral diacids and chiral alpha-methyl amines?

Organic & Biomolecular Chemistry Pub Date: 2012-06-13 DOI: 10.1039/C2OB25599E

Abstract

The three-component chiral derivatization protocols have been developed for 1H, 13C and 19F NMR spectroscopic discrimination of chiral diacids by their coordination and self-assembly with optically active (R)-α-methylbenzylamine and 2-formylphenylboronic acid or 3-fluoro-2-formylmethylboronic acid. These protocols yield a mixture of diastereomeric imino-boronate esters which are identified by the well-resolved diastereotopic peaks with significant chemical shift differences ranging up to 0.6 and 2.1 ppm in their corresponding 1H and 19F NMR spectra, without any racemization or kinetic resolution, thereby enabling the determination of enantiopurity. A protocol has also been developed for discrimination of chiral alpha-methyl amines, using optically pure trans-1,2-cyclohexanedicarboxylic acid in combination with 2-formylphenylboronic acid or 3-fluoro-2-fluoromethylboronic acid. The proposed strategies have been demonstrated on large number of chiral diacids and chiral alpha-methyl amines.

Graphical abstract: Simple and efficient methods for discrimination of chiral diacids and chiral alpha-methyl amines
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