A novel series of platelet receptor glycoprotein (Gp) IIb/IIIa antagonists with condensed heterocycles as their basic core was synthesized. In an in vitro assay, trans-4-(5- amidinobanzofuran-2-carboxamido) cyclohexyloxyacetic acid 17e and trans-3-[4-(5- amidinobanzofuran-2-carboxamido) cyclohexyl] propionic acid 17f produced marked inhibitions with IC 50 values of 0.018 and 0.006 μM, respectively in a human platelet ...