Abstract: Novel compounds of the formula I ##STR1## in which R.sup.1 and R.sup.2 are hydrogen, C.sub.1 -C.sub.4 alkyl or are linked to form C.sub.3 -C.sub.7 cycloalkyl and R.sup.3, R.sup.4 and R.sup.5 are the same or different and are hydrogen, C.sub.1 -C.sub.4 alkyl, hydroxy, OR.sup.6, SR.sup.6, halogen, NR.sup.7 R.sup.8, NO.sub.2, CN, CONR.sup.7 R.sup.8 or CO.sub.2 R.sup.9 wherein R.sup.6 is C.sub.1 -C.sub.4 alkyl or C.sub.7 -C.sub.10 aralkyl and R.sup.7, R.sup.8 and R.sup.9 are the same or different and are hydrogen, C.sub.1 -C.sub.4 alkyl or C.sub.7 -C.sub.10 aralkyl or R.sup.7 and R.sup.8 together with the nitrogen atom to which they are bound form 5 or 6 membered azacycloalkyl or oxazacycloalkyl; Arg is arginine ?NH--CH(CH.sub.2 CH.sub.2 CH.sub.2 NH--C(.dbd.NH)--NH.sub.2)--CO!; X is methine CH or nitrogen; n is an integer from 0 to 7; L is a peptide linker, and H is the carboxy terminal end of hirudin, and salts thereof, are provided.