<p>A compound of the formula (I): wherein RH represents one or more optional substituents on the fused cyclohexene ring; R1 is selected from H and halo; RN is selected from H and optionally substituted C1-10 alkyl; and RC1 and RC2 are independently selected from H, R, C(=O)OR, where R is optionally substituted C1-10 alkyl, optionally substituted C5-20 aryl or optionally substituted C3-20 heterocyclyl; RC1 and RC2 together with the carbon atom to which they are attached may form an optionally substituted spiro-fused C5-7 carbocylic or heterocyclic ring.</p>
