A compound having the formula or N-oxide, salt, stereoisomeric form, racemic mixture, or ester thereof wherein R 1 is hydrogen or C 1-6 -alkyl, R 2 is C 1-6 alkyl substituted by C 1-6 alkyloxy, hydroxyl, C 3-7 cycloalkyl, aryl, benzodioxolyl, Het 1, Het 2 or X wherein X is a carbon or nitrogen substituted by -C(=O)-NH 2, C 1-6 alkyloxy-C(=O)- or C 1-6 alkyl-C(=O)-, Aryl as a group or part of a group means phenyl which is substituted with one or more substituents independently selected from C 1-6 alkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, optionally mono- or disubstituted amino, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, Het 1, Het 2 optionally mono- or disubstituted aminocarbonyl, methylenedioxy, methylthio or methylsulfonyl, Het 1 as a group or part of a group is defined as a saturated or partially unsaturated monocyclic, bicyclic or tricyclic heterocycle having preferably 3 to 14 ring members, more preferably 5 to 10 ring members and more preferably 5 to 6 ring members, which contains one or more heteroatom ring members selected from nitrogen, oxygen or sulphur and which is optionally substituted on one or more nitrogen and/or carbon atoms by C 1-6 alkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, acetyl, oxo, optionally mono- or disubstituted amino, optionally mono- or disubstituted aminoalkyl, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, optionally mono- or disubstituted aminocarbonyl, methylthio, methylsulfonyl, aryl and a saturated or partially unsaturated monocyclic, bicyclic or tricyclic cycle or heterocycle having 3 to 14 ring members; and wherein Het 2 as a group or part of a group is defined as an aromatic monocyclic, bicyclic or tricyclic heterocycle having preferably 3 to 14 ring members, more preferably 5 to 10 ring members and more preferably 5 to 6 ring members, which contains one or more heteroatom ring members selected from nitrogen, oxygen or sulphur and which is optionally substituted on one or more nitrogen and/or carbon atoms by C 1-6 alkyl which may optionally substituted by C 3-7 cycloalkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, optionally mono- or disubstituted amino, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, optionally mono- or disubstituted aminocarbonyl, methylthio, methylsulfonyl, aryl, Het 1 and an aromatic monocyclic, bicyclic or tricyclic cycle or heterocycle having 3 to 12 ring members. R 1 is hydrogen or C 1-6 -alkyl, R 2 is C 1-6 alkyl substituted by C 1-6 alkyloxy, hydroxyl, C 3-7 cycloalkyl, aryl, benzodioxolyl, Het 1, Het 2 or X wherein X is a carbon or nitrogen substituted by -C(=O)-NH 2, C 1-6 alkyloxy-C(=O)- or C 1-6 alkyl-C(=O)-, Aryl as a group or part of a group means phenyl which is substituted with one or more substituents independently selected from C 1-6 alkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, optionally mono- or disubstituted amino, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, Het 1, Het 2 optionally mono- or disubstituted aminocarbonyl, methylenedioxy, methylthio or methylsulfonyl, Het 1 as a group or part of a group is defined as a saturated or partially unsaturated monocyclic, bicyclic or tricyclic heterocycle having preferably 3 to 14 ring members, more preferably 5 to 10 ring members and more preferably 5 to 6 ring members, which contains one or more heteroatom ring members selected from nitrogen, oxygen or sulphur and which is optionally substituted on one or more nitrogen and/or carbon atoms by C 1-6 alkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, acetyl, oxo, optionally mono- or disubstituted amino, optionally mono- or disubstituted aminoalkyl, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, optionally mono- or disubstituted aminocarbonyl, methylthio, methylsulfonyl, aryl and a saturated or partially unsaturated monocyclic, bicyclic or tricyclic cycle or heterocycle having 3 to 14 ring members; and wherein Het 2 as a group or part of a group is defined as an aromatic monocyclic, bicyclic or tricyclic heterocycle having preferably 3 to 14 ring members, more preferably 5 to 10 ring members and more preferably 5 to 6 ring members, which contains one or more heteroatom ring members selected from nitrogen, oxygen or sulphur and which is optionally substituted on one or more nitrogen and/or carbon atoms by C 1-6 alkyl which may optionally substituted by C 3-7 cycloalkyl, C 1-6 alkyloxy, aminoC 1-6 alkyl, halogen, hydroxy, optionally mono- or disubstituted amino, nitro, cyano, haloC 1-6 alkyl, carboxyl, C 1-6 alkoxycarbonyl, C 3-7 cycloalkyl, optionally mono- or disubstituted aminocarbonyl, methylthio, methylsulfonyl, aryl, Het 1 and an aromatic monocyclic, bicyclic or tricyclic cycle or heterocycle having 3 to 12 ring members.