A compound of formula wherein R 1 is halophenyl or cycloalkylalkoxy; R 2 is cycloalkyl, azetidinyl or difluoroazetidinyl; one of R 3 and R 4 is hydrogen and the other one is -(CR 5 R 6)-R 7 or -A-R 7; or R 2 is cycloalkyl and R 3 and R 4 together with the nitrogen atom to which they are attached form piperidinyl or piperidinylamine; R 5 and R 6 are independently selected from hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, phenyl, phenylalkyl and halophenyl; or R 5 and R 6 together with the carbon atom to which they are attached form cycloalkyl or oxetanyl; R 7 is cyano, carboxy, 5-methyl-[1,2,4]oxadiazol-3-yl, 5-amino-[1,2,4]oxadiazol-3-yl, 5-alkoxy-[1,2,4]oxadiazol-3-yl, thiazolyl, alkylthiazolyl, pyridinyl, alkylaminocarbonyl, hydroxyalkyl, alkoxyalkyl, aminocarbonyl, alkoxycarbonyl, dialkylaminocarbonyl, methanesulfonyl-alkyl, 2-[1,2,4]oxadiazol-5-yl)-alkyl, 2-methyl-2H-[1,2,4]triazol-3-yl, 2-(2-methyl-2H-[1,2,4]triazol-3-yl)-alkyl, 2,4-dihydro-[1,2,4]triazol-3-on-5-yl, 2-(2,4-dihydro-[1,2,4]triazol-3-on-5-yl)-alkyl, phenyl, phenylalkyl, pyridinylalkyl, pyrazolyl, pyrazolylalkyl, [1,2,4]triazol-1-yl, 2-([1,2,4]triazol-1-yl)-alkyl, alkylaminocarbonylalkyl, hydroxyalkylaminocarbonyl, hydroxyalkylaminocarbonylalkyl, haloalkylaminocarbonyl, 5-phenyl-2-methyl-oxazol-4-yl-alkyl, aminocarbonylalkyl or halogen; and A is cyclohexyl or thiophenyl; provided that when R 2 is azetidinyl or difluoroazetidinyl and R 7 is hydroxyalkyl, haloalkyl, thiazolyl, pyridinyl, 2-([1,2,4]oxadiazol-5-yl)-alkyl, pyridinylalkyl, pyrazolylalkyl, 2-([1,2,4]triazol-1-yl)-alkyl, aminocarbonyl or alkoxycarbonyl, then one of R 5 and R 6 is cycloalkyl, cycloalkylalkyl, phenyl, halophenyl or phenylalkyl and the other one is hydrogen or alkyl; or then R 5 and R 6 together with the carbon atom to which they are attached form cycloalkyl or oxetanyl; or a pharmaceutically acceptable salt or ester thereof. R 1 is halophenyl or cycloalkylalkoxy; R 2 is cycloalkyl, azetidinyl or difluoroazetidinyl; one of R 3 and R 4 is hydrogen and the other one is -(CR 5 R 6)-R 7 or -A-R 7; or R 2 is cycloalkyl and R 3 and R 4 together with the nitrogen atom to which they are attached form piperidinyl or piperidinylamine; R 5 and R 6 are independently selected from hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, phenyl, phenylalkyl and halophenyl; or R 5 and R 6 together with the carbon atom to which they are attached form cycloalkyl or oxetanyl; R 7 is cyano, carboxy, 5-methyl-[1,2,4]oxadiazol-3-yl, 5-amino-[1,2,4]oxadiazol-3-yl, 5-alkoxy-[1,2,4]oxadiazol-3-yl, thiazolyl, alkylthiazolyl, pyridinyl, alkylaminocarbonyl, hydroxyalkyl, alkoxyalkyl, aminocarbonyl, alkoxycarbonyl, dialkylaminocarbonyl, methanesulfonyl-alkyl, 2-[1,2,4]oxadiazol-5-yl)-alkyl, 2-methyl-2H-[1,2,4]triazol-3-yl, 2-(2-methyl-2H-[1,2,4]triazol-3-yl)-alkyl, 2,4-dihydro-[1,2,4]triazol-3-on-5-yl, 2-(2,4-dihydro-[1,2,4]triazol-3-on-5-yl)-alkyl, phenyl, phenylalkyl, pyridinylalkyl, pyrazolyl, pyrazolylalkyl, [1,2,4]triazol-1-yl, 2-([1,2,4]triazol-1-yl)-alkyl, alkylaminocarbonylalkyl, hydroxyalkylaminocarbonyl, hydroxyalkylaminocarbonylalkyl, haloalkylaminocarbonyl, 5-phenyl-2-methyl-oxazol-4-yl-alkyl, aminocarbonylalkyl or halogen; and A is cyclohexyl or thiophenyl; provided that when R 2 is azetidinyl or difluoroazetidinyl and R 7 is hydroxyalkyl, haloalkyl, thiazolyl, pyridinyl, 2-([1,2,4]oxadiazol-5-yl)-alkyl, pyridinylalkyl, pyrazolylalkyl, 2-([1,2,4]triazol-1-yl)-alkyl, aminocarbonyl or alkoxycarbonyl, then one of R 5 and R 6 is cycloalkyl, cycloalkylalkyl, phenyl, halophenyl or phenylalkyl and the other one is hydrogen or alkyl; or then R 5 and R 6 together with the carbon atom to which they are attached form cycloalkyl or oxetanyl;