Optically active hydantoin derivatives, their synthesis, pharmaceutical formulations containing them, and intermediates

Compounds of formula (I) having only two optically active centres, may exist as four isomers, each of which may be prepared by resolving a racemic amino-diester intermediate in the preparation thereof. The racemic amino-diester is selectively hydrolysed to the corresponding mono-ester which is acylated and subsequently selectively deacylated to produce the resolved mono-ester. Isomers of compounds of formula (I) having a particular configuration are biologically more active than the corresponding isomers having other configurations and are useful in medicine, either as the raw compound or in a pharmaceutical formulation, for example in inhibiting platelet aggregation.