Single enantionmers of compounds of formula (B), in either the cis or trans configuration, ##STR00001## wherein R.sup.1 and R.sup.2 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 (-) 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.