Orally Active GPIIb/IIIa Antagonists. Synthesis and Biological Activities of Masked Amidines as Prodrugs of 2-[(3S)-4-[(2S)-2-(4-Amidinobenzoylamino)-3-(4-methoxyphenyl)propanoyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiperazinyl] acetic Acid.
To improve the in vivo potency of the potentGPIIb/IIIaantagonist 2-[(3S)-4-[(2S)-2-(4-amidinobenzoylamino)-3-(4-methoxyphenyl)propanoyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiperazinyljacetic acid (4), the amidino group was converted to an oxadiazole ring, thiadiazole ring or substituted amidoxime group. These groups were expected to be metabolized to an amidino group in vivo. The compounds synthesized