The compound of formula 1b, or of formula 1b' wherein R 1 is selected from the group consisting of phenyl, Het and Hetaryl; which is optionally further substituted by one, two or three substituents Z, whereby each Z is a substituent selected from the group consisting of -OH, oxo, -CN, halogen, methyl, ethyl, n-propyl, isopropyl, -O-propyl, -C 1-6 -haloalkyl, three- to seven-membered cycloalkyl, Het, Hetaryl, -CO-N(CH 3) 2, -CO-NHCH 3, -CO-NH 2, -(C 1-3 -alkylene)-O-(C 1-3 -alkyl), -O- Het, which is optionally further substituted by one, two or three substituents X, whereby each X is selected from the group consisting of halogen, oxo, -O-C 1-4 -alkyl, -C 1-4 -haloalkyl, -O-(C 1-4 -alkylene)- Het, Het, -NH 2, whereby each substituent X is optionally further substituted by one, two or three substituents of a group selected from oxo, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, and wherein Het is selected from the group consisting of a five- to six-membered monocyclic heterocycle with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O, and a nine- to eleven-membered bicyclic heterocycle with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; Hetaryl is selected from the group consisting of a five- to six-membered monocyclic heteroaromate with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; and a nine- to eleven-membered bicyclic heteroaromate with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; and the pharmaceutically acceptable salts of the aforementioned compounds. R 1 is selected from the group consisting of phenyl, Het and Hetaryl; which is optionally further substituted by one, two or three substituents Z, whereby each Z is a substituent selected from the group consisting of -OH, oxo, -CN, halogen, methyl, ethyl, n-propyl, isopropyl, -O-propyl, -C 1-6 -haloalkyl, three- to seven-membered cycloalkyl, Het, Hetaryl, -CO-N(CH 3) 2, -CO-NHCH 3, -CO-NH 2, -(C 1-3 -alkylene)-O-(C 1-3 -alkyl), -O- Het, which is optionally further substituted by one, two or three substituents X, whereby each X is selected from the group consisting of halogen, oxo, -O-C 1-4 -alkyl, -C 1-4 -haloalkyl, -O-(C 1-4 -alkylene)- Het, Het, -NH 2, whereby each substituent X is optionally further substituted by one, two or three substituents of a group selected from oxo, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl, and wherein Het is selected from the group consisting of a five- to six-membered monocyclic heterocycle with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O, and a nine- to eleven-membered bicyclic heterocycle with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; Hetaryl is selected from the group consisting of a five- to six-membered monocyclic heteroaromate with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; and a nine- to eleven-membered bicyclic heteroaromate with 1, 2, 3 or 4 heteroatoms each independently from one another selected from N, S and O; and the pharmaceutically acceptable salts of the aforementioned compounds.