OPTICALLY-ACTIVE POLYURETHANES CONTAINING COUMARIN DIMER COMPONENT - SYNTHESIS, CHARACTERIZATION, AND CHIRAL RECOGNITION ABILITY

Optically-active polyurethanes (2a-2c) were prepared by polyaddition reaction of diamide (1a, 1b) and diester (1c) derivatives of chiral coumarin dimer with 4,4'-diphenylmethane diisocyanate (MDI) in chloroform and methyl ethyl ketone, respectively. The inherent viscosity of the polyurethanes are between 0.13 and 0.21 dL/g in N,N-dimethylacetamide (DMAc) at 30-degrees-C. Treated silica gels were absorbed with ca. 25 wt % of the polyurethanes, and packed as chiral stationary phases for direct optical resolution of 16 racemates with aromatic groups by high-performance liquid chromatography (HPLC). Polyurethanes 2a and 2b, obtained from diamide derivatives, show efficient resolution ability to some of the racemates (alpha = 1.06-1.79), especially the atropic (R5) and trans (R6-R9) isomers. The recognition ability of the polyurethanes can be attributed to the simultaneous aromatic stacking and hydrogen-bonding interactions with racemates.