We discovered a novel series of 3, 4-dihydro-2H-benzo [1, 4] oxazin-8-yloxyacetic acid derivatives as potent dual-acting agents to block the TXA2 receptor and to activate the PGI2 receptor. We report the synthesis, structure–activity relationship, and in vitro, ex vivo, and in vivo pharmacology of this series of compounds. 4-[2-(1, 1-Diphenylethylsulfanyl) ethyl]-3, 4- dihydro-2H-benzo [1, 4] oxazin-8-yloxyacetic acid N-methyl-d-glucamine salt (7) is a ...