A series of chiral interphenylene 7-oxabicyclo [2.2. l] heptane semicarbazones 19-26 were prepared and evaluated for their in vitro thromboxane (TxA,) antagonistic activity and in vivo duration of action. The potency of 19-26 was found to highly dependent on the substitution pattern of the interphenylene ring and decreased in the order ortho> meta>> para. SQ 35,091 (25),[lS-(la, 2a, 3a, 4a)]-2-[[3-[[[(phenylamino) carbonyl] hydrazono] methyl]-7- ...