A compound represented by the following general formula: <;CHEM>; wherein A is a further optionally substituted group represented by the formula: <;CHEM>; X is an oxygen atom, a sulfur atom, -SO- or -SO2; Y is an optionally substituted C6-14 aryl group, an optionally substituted 5- to 14-membered aromatic heterocyclic group or an optionally substituted C1-6 alkylene group; E is a single bond or -NR<;2>;-.