Abstract
1-Phenylethylamine was resolved into a pair of enantiomers by preferential crystallization of its cinnamic acid salt. A working hypothesis was proposed for the transformation of racemates into racemic mixtures (conglomerates) on the basis of structural correlation between 1-phenylethylamine and an achiral acid used. The validity of the hypothesis was verified by the success in the optical resolution of 1-phenyl-2- (p-tolyl) ethylamine, 1- (4-isopropylphenyl) ethylamine, 2- (anilinomethyl) - pyrrolidine, and 2-endo-benzamido-5-norbornene-1-endo-carboxylic acid by preferential crystallizations. erythro-2-Amino-1, 2-diphenylethanol was also resolved by preferential crystallization of its cinnamic acid salt and applied as a chiral auxiliary in the optical resolution of racemic acids, the enantioselective reduction of ketones, and the alkylation of ketones and acids. Optically active anti head-to-head coumarin dimer was obtained by the fractional crystallization of the diasteromeric diamides with 1-phenylethylamine. Optically active polyamides were prepared from the dimer and diamines and found to be useful as a chiral stationary phases for HPLC.
