AIM: The synthesis and antiaggregation activity of a series of compounds with p amidinophenyl group and tyrosine methyl esters as their terminals were studied. METHODS and RESULTS: A series of O (4 aminoiminomethylphenyloxy)alkyl N substituted L tyrosine methyl esters were prepared from 4 cyanophenol, L tyrosine and different dihalo alkanes. All compounds (IVa～i) were new compounds. Their in vitro activity against ADP induced platelet aggregation were tested. The structure activity relationships were discussed. CONCLUSION: Some of the compounds showed antiaggregation activity on platelet rich plasma at the final concerntration of 1×10 -6 mol·L -1 . The potency of IVa～i showed that compounds with three methylene groups are better than those with four methylene groups on the same R substituent in the above series of compounds.
