Abstract: The invention relates to the compounds of formula (I): ##STR1## in which: R.sub.1 denotes hydrogen, acyl, alkoxycarbonyl, benzyloxycarbonyl, phenoxycarbonyl or linear or branched C.sub.1 -C.sub.6 alkyl, substituted or unsubstituted, or R.sub.6 SO.sub.2 -- in which R.sub.6 denotes alkyl, naphthyl, phenyl, benzyl or morpholine,R.sub.2 denotes hydrogen or phenyl, substituted or unsubstituted benzyl, thienylmethyl, (pyridyl)methyl, diphenylmethyl, fluorenyl, naphthylmethyl, benzocyclobutyl, (dicyclopropylmethyl)methyl, indanyl or (C.sub.3 -C.sub.7 cycloalkyl)methyl,R'.sub.2 denotes hydrogen or elseR.sub.2 and R'.sub.2 together denote C.sub.6 H.sub.5 --CH.dbd.,R.sub.3 denotes any one of the groups as defined in the description, each of R.sub.4 and R.sub.5 denotes hydrogen or alkyl, or ##STR2## forms a boronic ester of pinanediol, A denotes the following group: ##STR3## in which n and A.sub.2 are as defined in the description, and medicinal products containing the same are useful as thrombin inhibitors.