The present invention relates to compounds of general formula (I-1) or (I-2) wherein R1 is hydrogen, lower alkyl, lower alkoxy, halogen, O(CH2)2-lower akoxy, O(CH2)2N(CH3)2, or O(CH2)-morpholinyl； R1' is hydrogen, lower alkyl, lower alkoxy, halogen, O(CH2)2-lower akoxy, O(CH2)2N(CH3)2, or O(CH2)-morpholinyl； with the proviso that both R1 and R1' may be simultaneously hydrogen, but only one of R1 and R1' is lower alkyl, lower alkoxy, halogen, O(CH2)2-lower akoxy, O(CH2)2N(CH3)2, or O(CH2)-morpholinyl； Het is a 5-or 6 membered heteroaryl group, wherein the heteroatom is selected from N, O or S； X is -CRR'-, -CRR'-NR'-, -C(O)-, -CH2-S-, -CH2-S(O)2-, CH2-O- or -CH2-CRR'-； R/R' are independently from each other hydrogen, lower alkyl, hydroxy or phenyl, or R and R' may form together with the carbon atom to which they are attached a cyclopropyl ring； R2 is lower alkyl, -C(O)O-lower alkyl, C3-6-cycloalkyl optionally substituted by lower alkyl or =O, bridged cyclohexyl or C3-6-cycloalkenyl, or is a 5-membered heteroaryl group, wherein the heteroatom is selected from N, O or S and which is optionally substituted by one or more lower alkyl, or is pyridinyl, optionally substituted by halogen or lower alkoxy； or is phenyl, optionally substituted by one or more R2', selected from halogen, cyano, S(O)2-lower alkyl, lower alkyl, lower alkyl substituted by halogen, lower alkoxy, lower alkoxy substituted by halogen or amino, or is benzo[1,3]dioxolyl, naphthyl, indolyl, benzo-isoxazolyl, 2,3-dihydro-1H-indenyl, optionally substituted by lower alkoxy or by an oxo group, or is 3,4-dihydro-2H- [1,4]oxazinyl, optionally substituted by an oxo group, or is a five or six membered heterocycloalkyl group； or to a pharmaceutically acceptable acid addition salt, to a racemic mixture or to its corresponding enantiomer and/or optical isomers thereof. The compounds may be used for the treatment or prophylaxis of schizophrenia, obsessive-compulsive personality disorder, major depression, bipolar dis
