Patent ID: 6956061

Claim:
A compound of the formula (I): wherein: R 1 is H, C 1 -C 6 -alkyl, C 2 -C 6 -alkenyl, C 2 -C 6 -alkynyl, or C 6 -C 14 -aryl, in which alkyl, alkenyl, alkynyl and aryl are unsubstituted or mono- to tri-substituted by a radical R 3 , R 2 is C 1 -C 6 -alkyl, C 2 -C 6 -alkenyl, C 2 -C 6 -alkynyl, or C 6 -C 14 -aryl, in which alkyl, alkenyl, alkynyl and aryl are unsubstituted or substituted n times by a radical R 3 , where n is an integer from 1 to 3, and R 3 is —OH, ═O, —O—C 1 -C 6 -alkyl, —O—C 2 -C 6 -alkenyl, —O—C 6 -C 14 -aryl, —NH—C 1 -C 6 -alkyl, —NH—C 2 -C 6 -alkenyl, —NH[—C(═O)—(C 1 -C 6 -alkyl)], —NH[—C(═O)—(C 6 -C 14 -aryl)], —NH 2 or halogen, when R 1 and R 2 are each independently alkyl, alkenyl and alkynyl, and when R 1 and R 2 are each independently aryl, R 3 is —OH, —O—C 1 -C 6 -alkyl, —O—C 2 -C 6 -alkenyl, —O—C 6 -C 14 -aryl, —NH—C 1 -C 6 -alkyl, —NH—C 2 -C 6 -alkenyl, —NH[—C(═O)—(C 1 -C 6 -alkyl)], —NH[—C(═O)—(C 6 -C 14 -aryl)], —NH 2 or halogen, in which alkyl and alkenyl can be further substituted by —CN, -amide or -oxime, and aryl can be further substituted by —CN or -amide, X 1 is CH 2 or O, X 2 , X 3 and X 4 independently of one another are O, NR 1 or S, wherein R 1 is as previously defined, or a stereoisomeric form of the compound of the formula (I) or a mixture of stereoisomers of a compound of the formula (I) in any ratio, or a physiologically tolerable salt of a compound of the formula (I) or a physiologically tolerable salt of a stereoisomeric form of a compound of the formula (I).