| abstract |
A compound of the formula in a balanced form, a pharmaceutically acceptable salt of this compound or a balanced form thereof, wherein R 1 is H, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy or C 6-10 aryl; R 2 is R 3 is OH, halogen, SH, O-C 1-6 alkyl or NH 2; and X and Y independently of one another are H or halogen, the compound being at least 80% pure when the purity is determined by standard analytical procedures, and the compound does not contain 15 additional dependent claims. |