4,4-disubstituted piperidine derivatives

A compound, of formula I:

• wherein
• R′ is selected from the group consisting of C2-7-alkyl, C2-7-alkenyl, C3-7-alkinyl, C3-7-cycloalkyl, halogen-C1-7-alkyl, C1-7-alkoxy-C1-7-alkyl and benzyl;
• R2 is selected from the group consisting of hydrogen, C1-7-alkyl,
• hydrogen, C1-7-alkyxy, C2-7-alkenyloxy,
• hydroxy-C1-7-alkoxy, C1-7-alkoxy-C1-7-alkoxy,
• —O-benzyl, —O—C3-7-cycloalkyl,
• halogen, halogen-C1-7-alkyl, halogen-C1-7-alkoxy,
• amino, pyrrolyl, imidazolyl,
• —C(O)OR6, wherein R6 is C1-7-alkyl, and
• unsubstituted phenyl or phenyl substituted by one to three groups independently selected from C1-7-alkyl, halogen and C1-7-alkoxy;
• R3 is hydrogen or C1-7-alkoxy;
• R4 and R5 are bonded to each other to form a ring together with the carbon atom to which they are attached, and R4 and R5 together are:
• —NH—C(O)—NH—C(O)—,
• and pharmaceutically acceptable salts thereof.