Compounds of the formula wherein A 1, A 2 and A 3 are selected from N or CH, provided that at least one of A 1, A 2 or A 3 is N and at least one of A 1, A 2 or A 3 is CH; R 1 is selected from the group consisting of C 1-7 -alkyl, C 3-7 -cycloalkyl, C 3-7 -cycloalkyl-C 1-7 -alkyl, hydroxy-C 1-7 -alkyl, C 1-7 -alkoxy-C 1-7 -alkyl, halogen-C 1-7 -alkyl, carbamoyl-C 1-7 -alkyl, C 1-7 -alkylcarbonylamino-C 1-7 -alkyl, phenyl-C 1-7 -alkyl, heterocyclyl-C 1-7 -alkyl wherein the heterocyclyl group refers to a saturated or partly unsaturated 3-, 4-, 5-, 6- or 7-membered ring which can comprise one, two or three heteroatoms selected from N, O or S and is unsubstituted or substituted by oxo, heteroaryl-C 1-7 -alkyl wherein the heteroaryl group refers to an aromatic 5- or 6-membered ring which can comprise one, two or three atoms selected from N, O or S or a bicyclic group comprising two 5- or 6-membered rings, in which one or both rings are aromatic and can contain one, two or three atoms selected from nitrogen, oxygen or sulfur and wherein the heteroaryl group is unsubstituted or mono- or di-substituted by C 1-7 -alkyl, and phenyl which is unsubstituted or mono- or di-substituted by halogen; R 2 and R 6 independently from each other are hydrogen or halogen; R 3 and R 5 independently from each other are selected from the group consisting of hydrogen, C 1-7 -alkyl, C 1-7 -alkoxy, halogen, halogen-C 1-7 -alkyl, halogen-C 1-7 -alkoxy and cyano; R 4 is selected from the group consisting of hydrogen, C 1-7 -alkoxy, halogen, halogen-C 1-7 -alkyl, halogen-C 1-7 -alkoxy and cyano; R 7 and R 8 together with the C atoms to which they are attached form a C 3-7 -cycloalkyl ring, or R 7 is hydrogen and R 8 is halogen-C 1-7 -alkyl or C 3-7 -cycloalkyl; R 9 is selected from the group consisting of hydrogen, C 1-7 -alkyl, halogen-C 1-7 -alkyl, C 1-7 -alkoxy-C 1-7 -alkyl and carbamoyl-C 1-7 -alkyl; and pharmaceutically acceptable salts thereof. A 1, A 2 and A 3 are selected from N or CH, provided that at least one of A 1, A 2 or A 3 is N and at least one of A 1, A 2 or A 3 is CH; R 1 is selected from the group consisting of C 1-7 -alkyl, C 3-7 -cycloalkyl, C 3-7 -cycloalkyl-C 1-7 -alkyl, hydroxy-C 1-7 -alkyl, C 1-7 -alkoxy-C 1-7 -alkyl, halogen-C 1-7 -alkyl, carbamoyl-C 1-7 -alkyl, C 1-7 -alkylcarbonylamino-C 1-7 -alkyl, phenyl-C 1-7 -alkyl, heterocyclyl-C 1-7 -alkyl wherein the heterocyclyl group refers to a saturated or partly unsaturated 3-, 4-, 5-, 6- or 7-membered ring which can comprise one, two or three heteroatoms selected from N, O or S and is unsubstituted or substituted by oxo, heteroaryl-C 1-7 -alkyl wherein the heteroaryl group refers to an aromatic 5- or 6-membered ring which can comprise one, two or three atoms selected from N, O or S or a bicyclic group comprising two 5- or 6-membered rings, in which one or both rings are aromatic and can contain one, two or three atoms selected from nitrogen, oxygen or sulfur and wherein the heteroaryl group is unsubstituted or mono- or di-substituted by C 1-7 -alkyl, and phenyl which is unsubstituted or mono- or di-substituted by halogen; R 2 and R 6 independently from each other are hydrogen or halogen; R 3 and R 5 independently from each other are selected from the group consisting of hydrogen, C 1-7 -alkyl, C 1-7 -alkoxy, halogen, halogen-C 1-7 -alkyl, halogen-C 1-7 -alkoxy and cyano; R 4 is selected from the group consisting of hydrogen, C 1-7 -alkoxy, halogen, halogen-C 1-7 -alkyl, halogen-C 1-7 -alkoxy and cyano; R 7 and R 8 together with the C atoms to which they are attached form a C 3-7 -cycloalkyl ring, or R 7 is hydrogen and R 8 is halogen-C 1-7 -alkyl or C 3-7 -cycloalkyl; R 9 is selected from the group consisting of hydrogen, C 1-7 -alkyl, halogen-C 1-7 -alkyl, C 1-7 -alkoxy-C 1-7 -alkyl and carbamoyl-C 1-7 -alkyl;