The present invention provides compounds of formula (I)
1
the prodrugs thereof, and the pharmaceutically acceptable salts of the compounds and prodrugs, wherein R
a
, R
b
, R
1
, and R
2
are as defined herein; pharmaceutical compositions thereof; and uses thereof.
本发明提供了式(I)的化合物
1
的前药,以及所述化合物和前药的药学上可接受的盐,其中R
a
,R
b
,R
1
和R
2
如本文所定义;其药物组合物;以及其用途。