The invention relates to compounds of formula (I) wherein R 1 is (A), or is phenyl, pyridinyl or pyridazinyl, wherein phenyl, pyridinyl and pyridazinyl may optionally be substituted by cyano, lower alkyl, halogen-substituted phenyl, lower alkyl-substituted [1,2,4]oxadiazol-3-yl or by 2-oxo-piperidin-1-yl; X is NR or O; R is C(O)-lower alkyl, -C(O)-cycloalkyl substituted by lower alkyl, cycloalkyl or is phenyl, pyridinyl or pyridazinyl, wherein phenyl, pyridinyl and pyridazinyl may optionally be substituted by lower alkyl, lower alkoxy, cyano, -C(O)-lower alkyl, halogen or lower alkyl substituted by halogen; R 2 is hydrogen or lower alkyl; R 3 is hydrogen, halogen, cyano, lower alkyl or lower alkyl substituted by halogen; R 4 is hydrogen or lower alkyl; wherein R 2 and R 4 are not simultaneously hydrogen or lower alkyl; R 5 is lower alkyl; R 6 halogen, hydroxy, lower alkyl, lower alkoxy, lower alkyl substituted by halogen, S(O) 2 -lower alkyl or cyano; or to a pharmaceutically suitable acid addition salt thereof. It has been found that the present compounds are high potential NK-3 receptor antagonists for the treatment of depression, pain, psychosis, Parkinson's disease, schizophrenia, anxiety and attention deficit hyperactivity disorder (ADHD).