| abstract |
The present invention relates to a compound of general formula 1, or its stereoisomer, pharmaceutically acceptable salt and/or hydrate, solvate or crystal form, wherein, R 1 represents C 1 -C 4 alkyl; R 2 and R 3 represents fluorine, or, R 2 represents fluorine, and R 3 represents methyl; R 4 and R 5 represent hydrogen, or, R 4 represents C 1 -C 6 acyl, and R 5 represents hydrogen, or, R 4 represents hydrogen, and R 5 represents C 1 -C 6 acyl, or, R 4 represents an optionally substituted aminoacyl, and R 5 represents hydrogen, or, R 4 represents hydrogen, and R 5 represents an optionally substituted aminoacyl; R 6 represents hydrogen, methyl, methoxy or halogen. |