A compound of the formula, wherein R 1 represents a heteroaryl or an aryl group which groups are independently unsubstituted, mono-, di-, or tri-substituted, wherein the substituents are independently selected from the group consisting of (C 1 -C 4)alkyl, (C 3 -C 6)cycloalkyl, (C 1 -C 4)alkoxy, (C 1 -C 3)fluoroalkyl, (C 1 -C 3)fluoroalkoxy, hydroxy, halogen and phenoxy; R 2 represents • heterocyclyl which is unsubstituted, mono- or di-substituted, wherein the substituents are independently selected from (C 1 -C 4)alkyl, (C 1 -C 4)alkylcarbonyl, (C 1 -C 4)alkoxycarbonyl, (C 1 -C 4)alkylsulfonyl, and halogen; • heterocyclyloxy; • (C 3 -C 6)cycloalkyl which is unsubstituted or mono- or di-substituted with halogen; • (C 3 -C 6)cycloalkyloxy; • N -(C 3 -C 6)cycloalkyl-amino; • N -(C 3 -C 6)cycloalkylmethyl-amino; • (C 3 -C 6)alkyl; • (C 2 -C 6)alkoxy; • N -(C 1 -C 4)alkylamino; • N,N -di-[(C 1 -C 4)alkyl]-amino; or • N -arylmethyl- N -(C,-C 4)alkyl-amino; R 3 represents hydrogen or halogen; R 4 represents hydrogen, fluoro, chloro, (C 1 -C 4)alkyl, (C 1 -C 4)alkoxy, (C 1 -C 4)alkyl-carbonyl, hydroxy-(C 1 -C 4)alkyl, hydroxy-(C 2 -C 4)alkoxy, (C 1 -C 2)alkoxy-(C 1 -C 4)alkyl or (C 1 -C 4)alkoxy-(C 2 -C 4)alkoxy; R 5 represents hydrogen or (C 1 -C 4)alkyl; and R 5 represents fluoro, chloro, methyl, ethyl or (C 1 -C 2)fluoroalkyl; or a salt of such a compound. R 1 represents a heteroaryl or an aryl group which groups are independently unsubstituted, mono-, di-, or tri-substituted, wherein the substituents are independently selected from the group consisting of (C 1 -C 4)alkyl, (C 3 -C 6)cycloalkyl, (C 1 -C 4)alkoxy, (C 1 -C 3)fluoroalkyl, (C 1 -C 3)fluoroalkoxy, hydroxy, halogen and phenoxy; R 2 represents • heterocyclyl which is unsubstituted, mono- or di-substituted, wherein the substituents are independently selected from (C 1 -C 4)alkyl, (C 1 -C 4)alkylcarbonyl, (C 1 -C 4)alkoxycarbonyl, (C 1 -C 4)alkylsulfonyl, and halogen; • heterocyclyloxy; • (C 3 -C 6)cycloalkyl which is unsubstituted or mono- or di-substituted with halogen; • (C 3 -C 6)cycloalkyloxy; • N -(C 3 -C 6)cycloalkyl-amino; • N -(C 3 -C 6)cycloalkylmethyl-amino; • (C 3 -C 6)alkyl; • (C 2 -C 6)alkoxy; • N -(C 1 -C 4)alkylamino; • N,N -di-[(C 1 -C 4)alkyl]-amino; or • N -arylmethyl- N -(C,-C 4)alkyl-amino; • heterocyclyl which is unsubstituted, mono- or di-substituted, wherein the substituents are independently selected from (C 1 -C 4)alkyl, (C 1 -C 4)alkylcarbonyl, (C 1 -C 4)alkoxycarbonyl, (C 1 -C 4)alkylsulfonyl, and halogen; • heterocyclyloxy; • (C 3 -C 6)cycloalkyl which is unsubstituted or mono- or di-substituted with halogen; • (C 3 -C 6)cycloalkyloxy; • N -(C 3 -C 6)cycloalkyl-amino; • N -(C 3 -C 6)cycloalkylmethyl-amino; • (C 3 -C 6)alkyl; • (C 2 -C 6)alkoxy; • N -(C 1 -C 4)alkylamino; • N,N -di-[(C 1 -C 4)alkyl]-amino; or • N -arylmethyl- N -(C,-C 4)alkyl-amino; R 3 represents hydrogen or halogen; R 4 represents hydrogen, fluoro, chloro, (C 1 -C 4)alkyl, (C 1 -C 4)alkoxy, (C 1 -C 4)alkyl-carbonyl, hydroxy-(C 1 -C 4)alkyl, hydroxy-(C 2 -C 4)alkoxy, (C 1 -C 2)alkoxy-(C 1 -C 4)alkyl or (C 1 -C 4)alkoxy-(C 2 -C 4)alkoxy; R 5 represents hydrogen or (C 1 -C 4)alkyl; and R 5 represents fluoro, chloro, methyl, ethyl or (C 1 -C 2)fluoroalkyl; or a salt of such a compound.