THE OPTICAL RESOLUTION OF 3-(2'-HYDROXY-2'-PHENYLETHYL)-2-THIAZOLIDINIMINE, AND THE CRYSTAL-STRUCTURE OF THE (2R,3R)-O,O'-DIBENZOYL HYDROGEN TARTRATE SALT OF THE (S)-(+)-ENANTIOMER

The optical resolution has been investigated for 3-(2'-hydroxy-2'-phenylethyl)-2-thiazolidinimine with (2R,3R)-O,O'-dibenzoyltartaric acid. The most effective separation of the enantiomers is attained if the resolution is performed in methanol with the reactants in a 1:1 ratio. The crystal structure at 122 K of the precipitating salt (C11H15N2OS+.C18H13O8-.CH3OH) has been determined by X-ray diffraction methods. Crystals are monoclinic, space group P2(1), with a = 7.5831(9), b = 12.5698(14), c = 15.835(2) angstrom, beta = 101.980(9)-degrees, V = 1476.5(3) angstrom3, Z = 2, D(x) = 1.378 g cm-3, mu = 15.00 cm-1. The crystal structure refined to R = 0.0255 for 6046 contributing reflections, established that the (+)D rotation of the cation corresponds to the S-enantiomer. The strongest intermolecular interactions are the short hydrogen bonds between the carboxylic acid and the carboxylate groups of anions related by translational symmetry along the a-axis. Methanol also plays a significant role in the hydrogen-bonding system. The packing mode in the present structure is compared to that of the mono-, dibenzoyl- and di-p-toluoyl hydrogen tartrates found in the Cambridge Structural Database.