A compound with the formula (I) and salts and solvates thereof, wherein: when there is a double bond present between C2 and C3, R2 is selected from the group consisting of: (ia) C5-10 aryl group, optionally substituted by one or more substituents selected from the group comprising: halo, nitro, cyano, ether, C1-7 alkyl, C3-7 heterocyclyl and bis-oxy-C1-3 alkylene； (ib) C1-5 saturated aliphatic alkyl； (ic) C3-6 saturated cycloalkyl； (id) (Formula (S)), wherein each of R11, R12 and R13 are independently selected from H, C1-3 saturated alkyl, C2-3 alkenyl, C2-3 alkynyl and cyclopropyl, where the total number of carbon atoms in the R2 group is no more than 5； (ie) (Formula (T)), wherein one of R15a and R15b is H and the other is selected from: phenyl, which phenyl is optionally substituted by a group selected from halo, methyl, methoxy； pyridyl； and thiophenyl； and (if) (Formula (U)), where R14 is selected from: H； C1-3 saturated alkyl； C2-3 alkenyl； C2-3 alkynyl； cyclopropyl； phenyl, which phenyl is optionally substituted by a group selected from halo, methyl, methoxy； pyridyl； and thiophenyl； when there is a single bond present between C2 and C3, R2 is (Formula (V)), where R16a and R16b are independently selected from H, F, C1-4 saturated alkyl, C2-3 alkenyl, which alkyl and alkenyl groups are optionally substituted by a group selected from C1-4 alkyl amido and C1-4 alkyl ester； or, when one of R16a and R16b is H, the other is selected from nitrile and a C1-4 alkyl ester； when there is a double bond present between C2' and C3', R12 is selected from the group consisting of: (ia) C5-10 aryl group, optionally substituted by one or more substituents selected from the group comprising: halo, nitro, cyano, ether, carboxy, ester, C1-7 alkyl, C3-7 heterocyclyl and bis-oxy-C1-3 alkylene； (ib) C1-5 saturated aliphatic alkyl； (ic) C3-6 saturated cycloalkyl； (id) (Formula (W)), wherein each of R21, R22 and R23 are independently selected from H, C1-3 saturated alkyl, C2-3 alkenyl,
