| abstract |
A compound of formula (I) wherein R1 represents C1-4alkyl or C1-4alkoxy; R2 represents C1-4alkyl or C1-4alkenyl; R3 represents H, F, Cl, methyl, methoxy or CF3; R4 represents H or F; X represents CH2 or C=O; and Y represents CH2 or C=O, provided that at least one of X and Y represents C=O and at least one of R3 and R4 is H; and pharmaceutically acceptable derivatives thereof, processes for preparing such compounds, a pharmaceutical composition comprising such compounds and the use of such compounds in medicine. |