Compounds of the formula (I): ##STR00001## wherein A and B together represent an optionally substituted, fused aromatic ring; X can be NR.sup.X or CR.sup.XR.sup.Y; if X=NR.sup.X then n is 1 or 2 and if X=CR.sup.XR.sup.Y then n is 1; R.sup.X is selected from the group consisting of H, optionally substituted C.sub.1-20 alkyl, C.sub.5-20 aryl, C.sub.3-20 heterocyclyl, amido, thioamido, ester, acyl, and sulfonyl groups; R.sup.Y is selected from H, hydroxy, amino; or R.sup.X and R.sup.Y may together form a spiro-C.sub.3-7 cycloalkyl or heterocyclyl group; R.sup.C1 and R.sup.C2 are both hydrogen, or when X is CR.sup.XR.sup.Y, R.sup.C1, R.sup.C2, R.sup.X and R.sup.Y, together with the carbon atoms to which they are attached, may form an optionally substituted fused aromatic ring; and R.sup.1 is selected from H and halo.