The design, synthesis, and pharmacological evaluation of (S)-(-)-ethyl [6-[4-( morpholinoformimidoyl) benzamido]-3, 4-dihydro-2 H-1-benzopyran-3-yl] acetate hydrochloride ((S)-4⊙ HCl, MS-180), an orally active glycoprotein IIb-IIIa (GPIIb-IIIa) antagonist, are reported. Pharmacophore mapping of amidino and carboxyl groups of already known GPIIb-IIIa antagonists led to the synthesis of nine amidino acids containing ...