| abstract |
A compound of formula (I): ** Formula ** or a pharmaceutically acceptable salt thereof, wherein: X is H, H; or O; Re is C (O) NRfRg or a 6-membered ring heteroaryl group containing 1 or 2 nitrogen atoms, wherein the heteroaryl group is optionally monosubstituted in a fluorine or chlorine ring carbon, or in a ring nitrogen with oxygen; Rf, Rg, R6 and R7 are each independently hydrogen or C1-C3 alkyl; R8 is C1-C4 alkyl, C3-C4 cycloalkyl or C4-C5 cycloalkylalkyl; R9 is methyl or ethyl; and R8 and R9 are optionally considered together to form a 6-member saturated ring containing 1 oxygen atom. |