The present invention relates to compounds of formula I wherein R1’ is CH3； R1 is methyl, ethyl, CF3, CH2OH, cyclopropyl or cyano, or R1’ and R1 may form together a 1,1-dioxo-tetrahydro-thiophen-3-yl ring； R2 is hydrogen, methyl, ethyl, isopropyl, tertbutyl, cyclopropyl, hydroxmethyl, or 2-propyl-2-ol； R3 is Cl, F, CF3, methyl, methoxy, isopropyl, cyano or cyclopropyl； R4 is hydrogen, methyl, F or Cl； or to a pharmaceutically acceptable salt or acid addition salt, to a racemic mixture, or to its corresponding enantiomer and/or optical isomer and/or stereoisomer thereof. The compounds of formula I may be used in the treatment of psychiatric disorders such as schizophrenia, bipolar disorder, obsessive-compulsive disorder or autism spectrum disorder.本發明係關於式I化合物其中R1' 為CH3；R1 為甲基、乙基、CF3、CH2OH、環丙基或氰基，或R1'及R1可一起形成1,1-二側氧基-四氫-噻吩-3-基環；R2 為氫、甲基、乙基、異丙基、第三丁基、環丙基、羥甲基或2-丙基-2-醇；R3 為Cl、F、CF3、甲基、甲氧基、異丙基、氰基或環丙基；R4 為氫、甲基、F或Cl；或係關於一種醫藥學上可接受之鹽或酸加成鹽，係關於一種外消旋混合物，或係關於其相應對映異構體及/或光學異構體及/或其立體異構體。該等式I化合物可用於治療諸如，精神分裂症、躁鬱症、強迫症或自閉症系列障礙之精神病症。
