CPC C07C 309/18 (2013.01) [A61K 9/1075 (2013.01); A61K 31/337 (2013.01); A61K 47/20 (2013.01); A61P 35/04 (2018.01)] | 9 Claims |
1. A compound of formula I or a pharmaceutically acceptable salt thereof,
wherein, R1, R2, R3, R4 and R5 are independently hydrogen, C1-C6 alkyl, C1-C6 alkoxy or C(═O)OR8; wherein R8 is C1-C4 alkyl;
R6 is
R7 is —OH, —NH2, —NHCH3, —N(CH3)2 or C1-4 alkoxy.
|