1,4-Benzoxazine-3(4H)-ones as potent inhibitors of platelet aggregation: design, synthesis and structure-activity relations.

A series of novel potentially platelet aggregation-inhibiting 1,4-benzoxazine-3(4H)-one derivatives was designed and synthesized through Smiles rearrangement, reduction and acetylation reactions. The antiaggregatory activities of the target molecules on arterial blood samples from rabbits, expressed by IC₅₀ values (μM), were then evaluated in vitro against ADP induced platelet aggregation. The favorable IC₅₀ values of compound 8c (IC₅₀=8.