| abstract |
There are provided compounds of formula (I) n nwhereinn R 1 represents O, S or NH; R 2 represents —C(═O)-aryl or —C(═O)-heteroaryl; R 3 represents hydrogen, methyl (which may be in either the α or β configuration) or methylene; R 4 and R 5 are the same or different and each represents hydrogen or halogen; and represents a single or a double bond; and salts and solvates thereof; process for preparing them, compositions containing them and their use in therapy. |