Compound of the formula in which R 1 represents a group of the formula where * is the point of attachment to the carbonyl group, X represents an oxygen atom, a sulphur atom or CH-R 6, where R 6 represents hydroxyl, R 2 represents hydrogen, C 1 -C 6 -alkyl, C 3 -C 6 -cycloalkyl or phenyl, where alkyl and cycloalkyl may be substituted by a substituent selected from the group consisting of hydroxy, methoxy, cyano, hydroxycarbonyl, aminocarbonyl, methylsulphonyl, difluoromethoxy and trifluoromethoxy, or where alkyl and cycloalkyl may be substituted by 1 to 3 fluorine substituents, R 3 represents hydrogen or C 1 -C 4 -alkyl, or R 2 and R 3 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 4 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl substituent, R 5 represents C 1 -C 4 -alkyl, or R 4 and R 5 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 7 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl or cyano substituent, or where alkyl may be substituted by 1 to 3 fluorine substituents, R 8 represents hydrogen, R 9 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl or cyano substituent, or where alkyl may be substituted by 1 to 3 fluorine substituents, R 10 represents hydrogen, R 11 represents C 1 -C 4 -alkyl, where alkyl may be substituted by a hydroxyl substituent, R 12 represents hydrogen or C 1 -C 4 -alkyl, or R 11 and R 12 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 13 represents hydroxymethyl or hydroxyethyl, R 14 represents methoxy or ethoxy, or one of the salts thereof, solvates thereof or solvates of the salts thereof. R 1 represents a group of the formula X represents an oxygen atom, a sulphur atom or CH-R 6, where R 6 represents hydroxyl, R 2 represents hydrogen, C 1 -C 6 -alkyl, C 3 -C 6 -cycloalkyl or phenyl, where alkyl and cycloalkyl may be substituted by a substituent selected from the group consisting of hydroxy, methoxy, cyano, hydroxycarbonyl, aminocarbonyl, methylsulphonyl, difluoromethoxy and trifluoromethoxy, or where alkyl and cycloalkyl may be substituted by 1 to 3 fluorine substituents, R 3 represents hydrogen or C 1 -C 4 -alkyl, or R 2 and R 3 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 4 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl substituent, R 5 represents C 1 -C 4 -alkyl, or R 4 and R 5 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 7 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl or cyano substituent, or where alkyl may be substituted by 1 to 3 fluorine substituents, R 8 represents hydrogen, R 9 represents hydrogen or C 1 -C 6 -alkyl, where alkyl may be substituted by a hydroxyl or cyano substituent, or where alkyl may be substituted by 1 to 3 fluorine substituents, R 10 represents hydrogen, R 11 represents C 1 -C 4 -alkyl, where alkyl may be substituted by a hydroxyl substituent, R 12 represents hydrogen or C 1 -C 4 -alkyl, or R 11 and R 12 together with the carbon atom to which they are attached form a cyclopropyl ring, cyclobutyl ring or cyclopentyl ring, where the cyclobutyl ring and the cyclopentyl ring may be substituted by a hydroxyl substituent, R 13 represents hydroxymethyl or hydroxyethyl, R 14 represents methoxy or ethoxy,