Compounds of the formula ##STR1## wherein L, M, R, T and X are set forth in the description, as well as hydrates or solvates thereof, which inhibit thrombin-induced platelet aggregation and clotting of fibrinogen in plasma, are described. The compounds of formula I are prepared by amidination or, depending on whether L is NH or O, by amide formation or esterification.

Compounds of the formula ##STR1## wherein L, M, R, T and X are set forth in the description, as well as hydrates or solvates thereof, which inhibit thrombin-induced platelet aggregation and clotting of fibrinogen in plasma, are described. The compounds of formula I are prepared by amidination or, depending on whether L is NH or O, by amide formation or esterification.