Compound corresponding to the formula: ##STR1## in which X represents one or more of hydrogen, halogen, alkyl, trifluoromethyl, alkoxy, alkylthio, methylsulphonyl, cyano, ethoxycarbonyl, aminocarbonyl and carboxy, Y represents one or more of hydrogen, halogens, alkyl, trifluoromethyl, methoxy and trifluoromethoxy, R.sub.1 represents hydrogen, alkyl, phenylmethyl, 2-phenylethyl, acetyl or alkoxycarbonyl, R.sub.2 and R.sub.3 each represent hydrogen, alkyl which is optionally substituted, prop-2-enyl, prop-2-ynyl, phenyl, 1-(phenylmethyl)piperidin-4-yl, or 1-[(cyclohexen-1-yl)methyl]piperidin-4-yl, or alternatively R.sub.2 and R.sub.3 form, with the nitrogen atom carrying them, an optionally substituted heterocycle. These compounds are useful as hypnotic, anxiolytic and anticonvulsant agents.