The present invention relates to novel compounds of formula (I)′ or a salt thereof:
wherein G is selected from a group consisting of: phenyl, a 5- or 6-membered monocyclic heteroaryl group, or a 8- to 11-membered heteroaryl bicyclic group; A is a group P1 or a group P2 wherein
P1 is
and the other groups are define in herein.