The present invention is dealing with compounds of the formula: ##STR1## and pharmaceutically acceptable salts thereof, in which n and m represent the number 1 or 2, X and Y hydrogen, alkyl (1-4 C), alkoxy (1-4 C), hydroxy, halogen, hydroxymethyl, trifluoromethyl, acyl (1-4 C), acyloxy (1-4 C) or the group NR.sub.x R.sub.y, in which R.sub.x and R.sub.y represent hydrogen, alkyl (1-4 C) or a sulphonyl group and R represents the group ##STR2## in which R.sub.1 and R.sub.2 represent hydrogen, alkyl (1-4 C), hydroxy, alkoxy (1-4 C), phenylalkoxy (7-10 C), acyloxy, amino or mono or dialkyl (1-4 C) amino, having potent platelet aggregation inhibiting properties.