This invention relates to compounds of the formula: ##STR1## wherein A.sup.1 to A.sup.5 form an accessible substituted seven-membered ring, which may be saturated or unsaturated, optionally containing up to two heteroatoms chosen from the group of O, S and N wherein S and N may be optionally oxidized; D.sup.1 to D.sup.4 form an accessible substituted six membered ring, optionally containing up to two nitrogen atoms; R is at least one substituent chosen from the group of R.sup.7, or Q--C.sub.1-4 alkyl, Q--C.sub.2-4 alkenyl, Q--C.sub.2-4 alkynyl, preferably substituted by an acidic function; R* is H, Q--C.sub.1-6 alkyl, Q--C.sub.1-6 oxoalkyl, Q--C.sub.2-6 alkenyl or Q--C.sub.2-4 alkynyl, C.sub.3-6 cycloalkyl, Ar or Het, optionally substituted by one or more substitutents; and R.sup.6 is preferably a substituent containing a basic nitrogen moiety; or a pharmaceutically acceptable salt thereof, which are effective for inhibiting platelet aggregation, pharmaceutical compositions for effecting such activity, and a method for inhibiting platelet aggregation.