| abstract |
Compounds of general formula 1 or stereoisomers thereof, their pharmaceutically acceptable salts and/or hydrates, solvates or crystalline forms, wherein R1 is C1-C4 alkyl; R2 and R3 are fluorine, or R2 is fluorine, and R3 is methyl; R4 and R5 are hydrogen, or R4 is C1-C6 acyl, and R5 is hydrogen, or R4 is hydrogen, and R5 is C1-C6 acyl, or R4 is optionally substituted aminoacyl, and R5 is hydrogen, or R4 is hydrogen, and R5 is optionally substituted aminoacyl; R6 is hydrogen, methyl, methoxy or halogen. |