Compounds of the general formula ##STR1## or their salts, esters or amide derivatives; and processes for their preparation. In the formula, R.sub.O represents hydrogen or lower alkyl, R.sub.2 represents hydrogen, halogen or nitro, R.sub.3 represents hydrogen or halogen, and R.sub.4 represents hydrogen or lower alkyl; and when R.sub.O is hydrogen, R.sub.2, R.sub.3 and R.sub.4 are all hydrogens and the group ##STR2## is present at the 2-position. These compounds exhibit superior analgesic and/or anti-inflammatory actions with little gastrointestinal troubles.