| abstract |
A compound of formula (I) and pharmaceutically acceptable salts, solvates and hydrolysable esters thereof wherein: X 1 is O or S; X 2 is O or S; n is 1-3; One of Y and Z is N, and the other is O; R 1 and R 2 are independently halogen, H, CH 3 , OCH 3 or C 1-3 alkyl; Each R 3 independently is halogen, CF 3 , C 1-6 straight or branched alkyl; R 4 and R 5 are independently H or C 1-3 alkyl. y is 0, 1, 2, 3, 4 or 5. |