Method for resolving racemic 2-amino-6-propylamino-4,5,6,7-tetrahydrobenzothiazole (I) or for enriching a mixture with an excess of one enantiomer. Method for resolving racemic 2-amino-6-propylamino-4,5,6,7-tetrahydrobenzothiazole (I) or for enriching a mixture with an excess of one enantiomer comprises； (a) reacting the racemate (or enriched mixture) with a chiral acid of formula (IV) as an organic solution, optionally mixed with water； and (b) (fractional) crystallization of a mono-salt, diastereomerically pure or enriched, of formula (V). R : phenyl or alkylphenyl； and X : anion of (IV). An independent claim is included for diastereoisomeric salts, optically pure or enriched, of formula (V). [Image] ACTIVITY : Antiparkinsonian； Neuroleptic； Hypotensive. No details of tests for these activities are given. MECHANISM OF ACTION : Dopamine D2 agonist.
