A compound of the formula I, or a pharmaceutically acceptable salt thereof, wherein R 1 is selected from the group consisting of phenyl substituted by R 1.1 and R 1.3, 5-6 membered heteroaryl containing 1 to 3 heteroatoms selected from the group consisting of S, N and O substituted by R 1.2 and R 1.5, 5-6 membered heterocyclyl containing 1 or 2 heteroatoms selected from the group consisting of S, N and O substituted by R 1.4; Wherein R 1.1 is selected from the group consisting of H, -CN, Br, Cl, F, C 1-4 -alkyl, C 3-5 -cycloalkyl, 5 membered heteroaryl optionally substituted by C 1-3 -alkyl, CF 3, F 3 C-CH 2, HF 2 C- H 2 N-S 2 -, H 3 C-NH-S 2 -, (H 3 C) 2 N-S 2 -, H 3 C-NH-CO-, C 1-4 -alkyl-O-, H 3 C-O-CO-. H 2 N-, (H 3 C) 2 N-, H 2 N-CO- and H 3 C-CO-NH-; R 1.2 is selected from the group consisting of H, -CN, Br, Cl, F, C 1-4 -alkyl, C 3-5 -cycloalkyl CF 3, F 3 C-CH 2, HF 2 C- H 2 N-S 2 -, H 3 C-NH-S 2 -, (H 3 C) 2 N-S 2 -, H 3 C-NH-CO-, C 1-4 -alkyl-O-, H 3 C-O-CO-. H 2 N-, (H 3 C) 2 N-, H 2 N-CO- and H 3 C-CO-NH-; wherein in the definition of R 1.1 and R 1.2 mentioned alkyl is optionally substituted by 1-3 F-atoms R 1.3 is selected from the group consisting of H, Cl, F, CN, C 1-4 -alkyl, and C 1-4 -alkyl-O-; R 1.4 is selected from the group consisting of H, -CN, Br, Cl, F and C 1-4 -alkyl optionally substituted by 1-3 F-atoms, R 1.5 H or C 1-4 -alkyl, R 2 and R 3 are independently from each other selected from the group consisting of H and C 1-3 -alkyl, or R 2 and R 3 together form a 3 to 6 membered carbocycle, a 4 to 6 membered heterocycle containing 1 O atom or 1 N atom or a 5 to 9 membered heteroaryl containing 1-2 N-atoms; R 4 denotes R 4.1 R 4.2 N- or NC-; or R 4 denotes a group of formula R 4.a wherein X denotes CH 2 or O; R 4.1 is selected from the group consisting of C 1-4 -alkyl-CO-, 6-membered heteroaryl containing 1-2 N-atoms, C 3-5 -cycloalkyl-CO- substituted by R 4.1.1 and R 4.1.2, Phenyl-CO- optionally substituted by 1-2 halogen atoms, C 1-4 -alkyl- or CH 3 -O- and 5 to 6 membered heteroaryl-CO- optionally substituted by C 1-4 -alkyl- or CH 3 -O-. wherein R 4.1.1, R 4.1.2 independently from each other are selected from the group consisting of H, -CH 3, F, and -CN; R 4.2 denotes H or C 1-3 -alkyl; R 5 denotes H or methyl; or R 4 and R 5 together form 4-6 membered heterocyclyl containing 1-2 heteroatoms selected from the group consisting of N and O; or a pharmaceutically acceptable salt thereof. R 1 is selected from the group consisting of phenyl substituted by R 1.1 and R 1.3, 5-6 membered heteroaryl containing 1 to 3 heteroatoms selected from the group consisting of S, N and O substituted by R 1.2 and R 1.5, 5-6 membered heterocyclyl containing 1 or 2 heteroatoms selected from the group consisting of S, N and O substituted by R 1.4; Wherein R 1.1 is selected from the group consisting of H, -CN, Br, Cl, F, C 1-4 -alkyl, C 3-5 -cycloalkyl, 5 membered heteroaryl optionally substituted by C 1-3 -alkyl, CF 3, F 3 C-CH 2, HF 2 C- H 2 N-S 2 -, H 3 C-NH-S 2 -, (H 3 C) 2 N-S 2 -, H 3 C-NH-CO-, C 1-4 -alkyl-O-, H 3 C-O-CO-. H 2 N-, (H 3 C) 2 N-, H 2 N-CO- and H 3 C-CO-NH-; R 1.2 is selected from the group consisting of H, -CN, Br, Cl, F, C 1-4 -alkyl, C 3-5 -cycloalkyl CF 3, F 3 C-CH 2, HF 2 C- H 2 N-S 2 -, H 3 C-NH-S 2 -, (H 3 C) 2 N-S 2 -, H 3 C-NH-CO-, C 1-4 -alkyl-O-, H 3 C-O-CO-. H 2 N-, (H 3 C) 2 N-, H 2 N-CO- and H 3 C-CO-NH-; wherein in the definition of R 1.1 and R 1.2 mentioned alkyl is optionally substituted by 1-3 F-atoms R 1.3 is selected from the group consisting of H, Cl, F, CN, C 1-4 -alkyl, and C 1-4 -alkyl-O-; R 1.4 is selected from the group consisting of H, -CN, Br, Cl, F and C 1-4 -alkyl optionally substituted by 1-3 F-atoms, R 1.5 H or C 1-4 -alkyl, R 2 and R 3 are independently from each other selected from the group consisting of H and C 1-3 -alkyl, R 4 denotes R 4.1 R 4.2 N- or NC-; or R 4 denotes a group of formula R 4.a wherein X denotes CH 2 or O; R 4.1 is selected from the group consisting of C 1-4 -alkyl-CO-, 6-membered heteroaryl containing 1-2 N-atoms, C 3-5 -cycloalkyl-CO- substituted by R 4.1.1 and R 4.1.2, Phenyl-CO- optionally substituted by 1-2 halogen atoms, C 1-4 -alkyl- or CH 3 -O- and 5 to 6 membered heteroaryl-CO- optionally substituted by C 1-4 -alkyl- or CH 3 -O-. wherein R 4.1.1, R 4.1.2 independently from each other are selected from the group consisting of H, -CH 3, F, and -CN; R 4.2 denotes H or C 1-3 -alkyl; X denotes CH 2 or O; R 4.1 is selected from the group consisting of C 1-4 -alkyl-CO-, 6-membered heteroaryl containing 1-2 N-atoms, C 3-5 -cycloalkyl-CO- substituted by R 4.1.1 and R 4.1.2, Phenyl-CO- optionally substituted by 1-2 halogen atoms, C 1-4 -alkyl- or CH 3 -O- and 5 to 6 membered heteroaryl-CO- optionally substituted by C 1-4 -alkyl- or CH 3 -O-. wherein R 4.1.1, R 4.1.2 independently from each other are selected from the group consisting of H, -CH 3, F, and -CN; R 4.2 denotes H or C 1-3 -alkyl; R 5 denotes H or methyl; or R 4 and R 5 together form 4-6 membered heterocyclyl containing 1-2 heteroatoms selected from the group consisting of N and O;