A compound of the formula <IMG> wherein X is hydrogen, halogen or nitro; Ar is phenyl or naphthyridinyl which may optionally be substituted; and either one of Z1 and Z2 is hydrogen and the other is lower alkanoyloxy or hydroxy, each of Z1 and Z2 is lower alkoxy, or Z1 and Z2 combinedly represent hydroxyimino, oxo or a group of the formyla: <IMG> in which Y is oxygen or sulfur and A is a branched or unbranched lower alkylene chain; and a salt thereof, act on the central nervous system but are weak in adverse effects such as hypnotic and muscle relaxant effects.
3-(PIPERIDIN-1-YL)-CARBONYLMETHYL-ISOINDOLIN-1-ONE