Compounds of formula (I)
as well as pharmaceutically acceptable salts thereof can be used in the form of pharmaceutical compositions, wherein A
1
, A
2
, R
1
, R
2
, R
3
and R
4
have the significance given in claim
1.
化合物的
化学式(I)
以及其药学上可接受的盐可以用于制成药物组合物的形式,其中A
1
,A
2
,R
1
,R
2
,R
3
和R
4
具有权利要求中给定的含义。