Some pyrrolidine and pyrrolizine derivatives as inhibitors of blood platelet aggregation.

N-Substituted 4-(substituted benzylidene)pyrrolidine-2,3-diones and 2-substituted benzylidene pyrrolizine-1-ones-inhibit blood platelet aggregation when tested against collagen induced aggregation in citrated human blood. The pyrrolidine derivatives showed potency closely related to the Hammett functions of the substitutents on the benzene rings. Maximal potency was observed in N-isopropyl-4-(2',6'-dichlorobenzylidene pyrrolidine-2,3-dione. The pyrrolizine derivatives were much less active.