Patent ID: 6841562

Claim:
A compound of the formula (I): wherein: R 1a is hydrogen, halogen, hydroxyl, amino, alkylamino, dialkylamino, hydroxyamino, alkoxyamino or alkylalkoxyamino; and R 1b is hydrogen; or R 1a and R 1b form an oxo group; R 2 is carboxyl, carboxymethyl or hydroxymethyl; R 3 is C 1-6 alkyl substituted with phenylthio, C 3-7 cycloalkylthio or 5- to 6-membered heteroarylthio; or propargyl substituted with phenyl, C 3-7 cycloalkyl or 5- to 6-membered heteroaryl; wherein said heteroaryl is having 1 to 4 heteroatoms chosen from nitrogen, oxygen and sulfur; and wherein said phenyl or said heteroaryl is optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxyl, alkyl, alkyloxy, trifluoromethyl, trifluoromethoxy, carboxyl, alkyloxycarbonyl, cyano and amino; and wherein said cycloalkyl is optionally substituted with one or more substituents chosen from halogen and trifluoromethyl; and R 4 is C 1-6 alkyl, C 2-6 alkenyl-CH 2 — or C 2-6 alkynyl-CH 2 —, C 3-8 cycloalkyl or C 3-8 cycloalkylalkyl; or an isomer, an enantiomer, a diastereoisomer or a mixture thereof, or a pharmaceutically acceptable salt thereof.