| abstract |
The compounds of general formula 1 or their stereoisomers, pharmaceutically acceptable salts and / or hydrates, solvates or crystalline forms, where R is C-C1-6 alkyl; R5 and R4 are fluorine, or R5 is fluorine, and R5 is methyl; R5 and R2 are hydrogen, or R5 is C-Sacyl, R5 is hydrogen, or R5 is hydrogen, is optionally substituted α-aminoacyl; R4 is hydrogen, methyl, methoxy or halogen. |