Design of chiral polymers for the kinetic resolution of racemic conglomerates

Abstract

The design of chiral polymers as stereospecific inhibitors for efficient kinetic resolution of conglomerates by crystallization is described. The selection of the polymers is done on the basis of the crystal structure and the morphology of the substrate. The resolutions with the polymers are better than those previously obtained with low molecular weight additives. This is illustrated here for the comparative resolutions of (R,S)-glutamic acid (Glu · HCl), (R,S)-threonine, (Thr), (R,S)-asparagine monohydrate, (Asn · H2O), and (R,S)-p-hydroxyphenylglycine-p-toluenesulfonate, (pHpgpTs). Further, (R,S)-histidine, which could not be resolved with the low molecular weight inhibitors, was successfully resolved with two polymeric reagents. The method is also applicable for molecular crystals lacking ionic and hydrogen bonds as is illustrated for the resolution of (R,S)-sec-phenethyl-3,5-dinitrobenzoate (PDNB). Finally, a simultaneous resolution of the enantiomers in a device composed of two compartments separated by a membrane is described. © 1987.