Single enantionmers of compounds of formula (B), in either the cis or trans configuration, wherein R1 and R2 are as defined herein, can be separated from enantiomeric mixtures thereof by reacting the compound with an acid to produce a conglomerate salt that has the following characteristics: the IR spectrum of the salt of the racemic compound, a 1:1 mixture of (&minus；) and (+) crystals, is identical to that of the each of the single enantiomer, and the salt of the racemic compound has a melting point lower that that of either single enantiomer. The conglomerate salt is then separated by preferential crystallization.
