A compound of formula wherein R 1 is cycloalkylalkoxy, halophenyl, tetrahydrofuranylalkoxy, halophenylalkyl, haloalkyloxy, alkylsulfonyl, tetrahydropyranylalkoxy or halogen; R 2 is alkyl, pyrrolidinyl, cycloalkyl, haloazetidinyl, haloalkyl, cycloalkylalkoxy, haloalkyloxy, halocycloalkyl, hydroxycycloalkyl or halooxetanyl; one of R 3 and R 4 is alkyl, cycloalkyl, haloalkyl or hydroxyalkyl and the other one is alkyl, alkyloxyalkyl, (haloazetidinyl)(cycloalkyloxy)pyridinylcarbonyloxyalkyl, haloalkylcycloalkyl, hydroxyalkyl, phenylalkyl, alkoxycarbonylalkyl, carboxyalkyl, alkylaminocarbonylalkyl, (alkyloxadiazolyl)(cycloalkylalkyl)alkyl, (alkyloxadiazolyl)(cycloalkyl)alkyl, pyridazinylalkyl, aminocarbonylalkyl, alkyloxadiazolylalkyl, alkyltetrazolylalkyl, formyl, phenyl, dialkylpyrazolyl, alkylcarbonylpiperidinyl or cycloalkylalkyl; or R 3 and R 4 together with the nitrogen atom to which they are attached form heterocyclyl or substituted heterocyclyl; wherein heterocyclyl is 6-oxa-1-aza-spiro[3.3]heptyl, oxazolidinyl, morpholinyl, pyrrolidinyl, piperazinyl, 2-oxa-5-aza-spiro[3.4]octyl, piperidinyl, 6-aza-bicyclo[3.2.1.]octyl, imidazolidinyl, 4-aza-spiro[2.4]heptyl, 2-aza-bicyclo[2.2.1]heptyl, 2-thia-5-aza-bicyclo[2.2.1]heptyl, 2,5-diazabicyclo[2.2.1]heptyl, 2-oxa-5-aza-bicyclo[2.2.1]heptyl, hexahydrofuro[2,3-c]pyrrolyl, 2-thia-6-aza-spiro[3.3]heptyl, 1,8-diaza-spiro[4.5]decyl, 1-oxa-7-aza-spiro[4.4]nonyl, 5-oxa-2-aza-spiro[3.4]octyl, 8-oxa-3-aza-bicyclo[3.2.1]octyl, 3-oxa-8-aza-bicyclo[3.2.1]octyl, thiomorpholinyl, thiazolidinyl, 5-aza-spiro[3.4]octyl, azetidinyl, 5-aza-spiro[2.4]heptyl, 3-aza-bicyclo[3.1.0]hexyl or 5-aza-spiro[2.4]heptyl, 1,3,3a,4,6,6a-hexahydrofuro[3,4-c]pyrrolyl; and wherein substituted heterocyclyl is heterocyclyl substituted with one to four substituents independently selected from alkyl, oxo, hydroxyl, carboxyl, alkylcarbonylamino, alkyloxyalkyl, hydroxyalkyl, aminocarbonyl, halogen, phenylalkyl, phenyl, alkoxycarbonyl, cycloalkylalkyl, phenylalkoxycarbonyl, cycloalkyl, halohydroxyalkyl and haloalkyl; provided that R 3 and R 4 together with the nitrogen atom to which they are attached don't form unsubstituted piperidinyl, unsubstituted thiomorpholinyl or hydroxyalkylpyrrolidinyl; or a pharmaceutically acceptable salt or ester thereof. R 1 is cycloalkylalkoxy, halophenyl, tetrahydrofuranylalkoxy, halophenylalkyl, haloalkyloxy, alkylsulfonyl, tetrahydropyranylalkoxy or halogen; R 2 is alkyl, pyrrolidinyl, cycloalkyl, haloazetidinyl, haloalkyl, cycloalkylalkoxy, haloalkyloxy, halocycloalkyl, hydroxycycloalkyl or halooxetanyl; one of R 3 and R 4 is alkyl, cycloalkyl, haloalkyl or hydroxyalkyl and the other one is alkyl, alkyloxyalkyl, (haloazetidinyl)(cycloalkyloxy)pyridinylcarbonyloxyalkyl, haloalkylcycloalkyl, hydroxyalkyl, phenylalkyl, alkoxycarbonylalkyl, carboxyalkyl, alkylaminocarbonylalkyl, (alkyloxadiazolyl)(cycloalkylalkyl)alkyl, (alkyloxadiazolyl)(cycloalkyl)alkyl, pyridazinylalkyl, aminocarbonylalkyl, alkyloxadiazolylalkyl, alkyltetrazolylalkyl, formyl, phenyl, dialkylpyrazolyl, alkylcarbonylpiperidinyl or cycloalkylalkyl; or R 3 and R 4 together with the nitrogen atom to which they are attached form heterocyclyl or substituted heterocyclyl; wherein heterocyclyl is 6-oxa-1-aza-spiro[3.3]heptyl, oxazolidinyl, morpholinyl, pyrrolidinyl, piperazinyl, 2-oxa-5-aza-spiro[3.4]octyl, piperidinyl, 6-aza-bicyclo[3.2.1.]octyl, imidazolidinyl, 4-aza-spiro[2.4]heptyl, 2-aza-bicyclo[2.2.1]heptyl, 2-thia-5-aza-bicyclo[2.2.1]heptyl, 2,5-diazabicyclo[2.2.1]heptyl, 2-oxa-5-aza-bicyclo[2.2.1]heptyl, hexahydrofuro[2,3-c]pyrrolyl, 2-thia-6-aza-spiro[3.3]heptyl, 1,8-diaza-spiro[4.5]decyl, 1-oxa-7-aza-spiro[4.4]nonyl, 5-oxa-2-aza-spiro[3.4]octyl, 8-oxa-3-aza-bicyclo[3.2.1]octyl, 3-oxa-8-aza-bicyclo[3.2.1]octyl, thiomorpholinyl, thiazolidinyl, 5-aza-spiro[3.4]octyl, azetidinyl, 5-aza-spiro[2.4]heptyl, 3-aza-bicyclo[3.1.0]hexyl or 5-aza-spiro[2.4]heptyl, 1,3,3a,4,6,6a-hexahydrofuro[3,4-c]pyrrolyl; and wherein substituted heterocyclyl is heterocyclyl substituted with one to four substituents independently selected from alkyl, oxo, hydroxyl, carboxyl, alkylcarbonylamino, alkyloxyalkyl, hydroxyalkyl, aminocarbonyl, halogen, phenylalkyl, phenyl, alkoxycarbonyl, cycloalkylalkyl, phenylalkoxycarbonyl, cycloalkyl, halohydroxyalkyl and haloalkyl; provided that R 3 and R 4 together with the nitrogen atom to which they are attached don't form unsubstituted piperidinyl, unsubstituted thiomorpholinyl or hydroxyalkylpyrrolidinyl; or a pharmaceutically acceptable salt or ester thereof.