DESIGN, SYNTHESIS AND BIOLOGICAL-ACTIVITY OF NOVEL RIGID AMIDINO-PHENYLALANINE DERIVATIVES AS INHIBITORS OF THROMBIN

halene-2-sulfonylamino)-1-[2R-(4-amidinophenyl)-1- piperidinocarbonyle thyl]-2-pyrrolidinone (1a) is a potent inhibitor of thrombin with an I C50 value by 112 times lower than that of NAPAP (racemate). The select ivity versus trypsin can be improved by incorporation of substituents on the naphthyl ring. The mode of binding of the compound was determin ed by X-ray crystallography.