abstract |
Compounds of formula (I) or a pharmaceutically acceptable derivative thereof: wherein W, X, Y, Z, R<SUP>1</SUP>, R<SUP>2a</SUP>, R<SUP>2b</SUP>, and R<SUP>x</SUP>, R<SUP>8 </SUP>and R<SUP>9 </SUP>are as defined in the specification, a process for the preparation of such compounds, pharmaceutical compositions comprising such compounds and the use of such compounds in medicine. |