PROBLEM TO BE SOLVED : To provide pharmaceuticals and pharmaceutical compositions as primary or adjunct therapy in treatment of acute and residual phases of schizophrenia. SOLUTION : The invention provides a compound represented by formula I in a free or pharmaceutically acceptable salt form. (X is -O-, -NH-, or -N(CH3)-; and Y is -O-, -C(R2)(OH)-, -C(R3)(OR1)-, -C(O)-, where R1 is -C1-6 alkyl, or -C(O)-C1-21 alkyl, and R2 and R3 are H or -C1-6 alkyl.) SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT