Patent ID: 7262184

Claim:
A compound corresponding to the formula I: wherein R 1 is hydrogen or a group forming a biolabile ester, R 2 is hydrogen, C 1-4 -alkyl or C 1-4 -hydroxyalkyl, the hydroxyl group of which is optionally esterified with C 2-4 -alkanoyl or an amino acid, and R 3 is C 1-4 -alkyl; C 1-4 -alkoxy-C 1-4 -alkyl; C 1-4 -hydroxyalkyl, which is optionally substituted by a second hydroxyl group and the hydroxyl groups of which are each optionally esterified with C 2-4 -alkanoyl or an amino acid; (C 0-4 -alkyl) 2 amino-C 1-6 -alkyl; C 3-7 -cycloalkyl; C 3-7 -cycloalkyl-C 1-4 -alkyl; phenyl-C 1-4 -alkyl, the phenyl group of which is optionally substituted once or twice by C 1-4 -alkyl, C 1-4 -alkoxy or halogen; naphthyl-C 1-4 -alkyl; C 3-6 -oxoalkyl; phenylcarbonylmethyl, the phenyl group of which is optionally substituted once or twice by C 1-4 -alkyl, C 1-4 -alkoxy or halogen, or 2-oxoazepanyl, or R 2 and R 3 together are C 4-7 -alkylene, the methylene groups of which are optionally replaced once or twice by carbonyl, nitrogen, oxygen or sulphur, or which are optionally substituted once by hydroxy, which is optionally esterified with C 2-4 -alkanoyl or an amino acid; C 1-4 -alkyl; C 1-4 -hydroxyalkyl, the hydroxyl group of which is optionally esterified with C 2-4 -alkanoyl or an amino acid residue; phenyl or benzyl, and R 4 is hydrogen or a group forming a biolabile ester, or a physiologically acceptable salt thereof.