Novel compounds of the formula ##STR1## wherein X is in the 5,6,7 or 8 position and is selected from the group consisting of hydrogen, halogen, alkyl of 1 to 5 carbon atoms, alkoxy of 1 to 4 carbon atoms, CF.sub.3 O--, CF.sub.3 S-- and CF.sub.3 --, R.sub.1 ' is selected from the group consisting of hydrogen and alkyl of 1 to 4 carbon atoms, R.sub.2 ' is selected from the group consisting of hydrogen or an optionally unsaturated ring able to contain one or more heteroatoms of the group consisting of --S--, --O-- and --N-- optionally substituted with one or more members of the group consisting of (a) halogens, (b) alkyl of 1 to 4 carbon atoms optionally substituted with NH.sub.2, --NHAlK or --N---(AlK).sub.2 and AlK is alkyl of 1 to 3 carbon atoms, (c) phenyl, (d) alkoxy of 1 to 4 carbon atoms, (e) --OH, (f) --CF.sub.3 and (g) --NO.sub.2 or R.sub.1 ' together with the nitrogen atom to which they are attached form an optionally unsaturated ring, the said ring then being connected to the nitrogen atom by a double bond, R.sub.3 is selected from the group consisting of hydrogen, halogen and alkyl of 1 to 4 carbon atoms, R.sub.4 is selected from the group consisting of hydrogen and halogen, R.sub.5 is a halogen with the proviso that R.sub.3, R.sub.4 and R.sub.5 can not all be fluorine and R.sub.6 is selected from the group consisting of hydrogen, alkyl of 1 to 8 carbon atoms and an acyl of an organic carboxylic acid of 2 to 8 carbon atoms and their non-toxic, pharmaceutically acceptable acid addition salts and their salts with non-toxic, pharmaceutically acceptable bases having a remarkable analgesic activity, a very weak anti-inflammatory activity and a good tolerance by the gastrointestinal system and their preparation and their intermediates.