Detection of chirality of poly(glycerol methacrylate)s after derivatization by 1H NMR spectroscopy

Chiral poly(glycerol methacrylate)s (PGMAs) are synthesized via ATRP using enantiopure solketal methacrylates followed by acidic hydrolysis. The optical activity of the polymers is confirmed by measurements of the circular dichroism. Furthermore, the chirality of the PGMAs containing repeat units with diol groups is determined via 1H NMR spectroscopy employing a three-component chiral derivatizing process, involving the treatment of enantiopure polymers with 2-formylphenylboronic acid and enantiopure α-methylbenzylamine (MBA), which yields cyclic boronate diastereoisomers on the pendant groups. The detection of the chirality of the PGMAs is based on the anisotropic shielding/deshielding effect of the phenyl group in (R)- or (S)-MBA. The main advantage of this method is its simplicity as it only involves the mixing of all the components without any further purification steps. This procedure has been applied here for the first time to chiral polymers.