ty optionally substituted with iso-propyl in the ortho position. [0917] In yet another embodiment of the present invention, the active compound is of formula (II), its pharmaceutically acceptable salts or prodrugs thereof, wherein: [0918] i) X is O; [0919] ii) R1 is fluorine or hydrogen; [0920] iii) R3 and R3??? are independently hydrogen or fluorine; R4 is hydrogen; and [0921] iv) R2 is a phenyl