GPIIb/IIIa Integrin Antagonists with the New Conformational Restriction Unit, Trisubstituted β-Amino Acid Derivatives, and a Substituted Benzamidine Structure

Ethyl N-[3-(2-fluoro-4-(thiazolidin-3-yl(imino)methyl)benzoyl)amino-2,2-dimethylpentanoyl]piperidine-4-acetate 40 (NSL-96184) is a highly potent and orally active fibrinogen receptor antagonist, which is characterized by the presence of the trisubstituted β-amino acid residue, 3-ethyl-2,2-dimethyl-β-alanine. This compound was developed on the basis of the SAR study of N-[3-(N-4-amidinobenzoyl)amino-2,2-dimethyl-3-phenylpropionyl]piperidine-4-acetic acid 1 (NSL-95301) with the derivatization focused on the central trisubstituted β-amino acid unit as well as the basic amidinobenzoyl unit, and the esterification of the carboxyl group for prodrug composition. Compound 1, which was reported in our previous study, was discovered by the application of combinatorial chemistry. The molecular modeling study suggests that the trisubstituted β-amino acid unit is responsible for fixing the molecule to its active conformation. Compound 40 showed an excellent profile in the in vitro and in vivo studies for its human pla...