A compound of formula XXIV, wherein: Y represents -C -Z; R 1, R 3 and R 4 independently represent hydrogen, halo, -NO 2, -CN, -C 2 R x1, -OR x2, -SR x3, -S R x4, -S 2 R x5, -N(R x6)R x7, -N(R x8)C R x9, -N(R x10)S 2 R x11 or R x12; R 2 represents -NO 2; X represents hydrogen or C 1-6 alkyl optionally substituted by one or more halo atoms; Z represents aryl or heteroaryl, both of which are optionally substituted by one or more substituents selected from -OR a, halo, -NO 2 -CN, -C 2 R a1, -SR a3, -S R a4, -S 2 R a5, -N(R a6)R a7, -N(R a8)C R a9, -N(R a10)S 2 R a11 and R a12; R a represents an oxy-protecting group, hydrogen or C 1-6 alkyl optionally substituted by one or more substituents selected from halo, -C 2 R b1 and -N(R b2)R b3, wherein the oxy-protecting group is selected from the group consisting of trialkylsilyl and diarylalkyl-silyl groups, tetrahydropyranyl, -C R t1, C 1-6 alkyl (which alkyl group is optionally substituted by one or more substituents selected from optionally substituted phenyl), -S 2 R t2, -C OR t3, -C N(R t4)R t5 and inorganic metal salts; R t1 represents C 1-6 alkyl or optionally substituted phenyl; R t2 represents optionally substituted phenyl; R t3 represents optionally substituted phenyl or C 1-6 (e.g. C 1-4) alkyl; R t4 and R t5 independently represent hydrogen, C 1-6 alkyl, optionally substituted phenyl or -C R t6; R t6 represents C 1-6 alkyl or optionally substituted phenyl; R x1, R x2, R x3, R x6, R x7, R x8, R x9, R x10, R a1, R a3, R a6, R a7, R a8, R a9, R a10, R b1, R b2 and R b3 independently represent hydrogen or C 1-6 alkyl optionally substituted by one or more halo atoms; R x4, R x5, R x11, R x12, R a4, R a5, R a11 and R a12 independently represent C 1-6 alkyl optionally substituted by one or more halo atoms; and wherein optional substituents on phenyl groups are selected from halo, -NO 2, -OH and/or -OC 1-6 alkyl, or a salt or solvate thereof. Y represents -C -Z; R 1, R 3 and R 4 independently represent hydrogen, halo, -NO 2, -CN, -C 2 R x1, -OR x2, -SR x3, -S R x4, -S 2 R x5, -N(R x6)R x7, -N(R x8)C R x9, -N(R x10)S 2 R x11 or R x12; R 2 represents -NO 2; X represents hydrogen or C 1-6 alkyl optionally substituted by one or more halo atoms; Z represents aryl or heteroaryl, both of which are optionally substituted by one or more substituents selected from -OR a, halo, -NO 2 -CN, -C 2 R a1, -SR a3, -S R a4, -S 2 R a5, -N(R a6)R a7, -N(R a8)C R a9, -N(R a10)S 2 R a11 and R a12; R a represents an oxy-protecting group, hydrogen or C 1-6 alkyl optionally substituted by one or more substituents selected from halo, -C 2 R b1 and -N(R b2)R b3, wherein the oxy-protecting group is selected from the group consisting of trialkylsilyl and diarylalkyl-silyl groups, tetrahydropyranyl, -C R t1, C 1-6 alkyl (which alkyl group is optionally substituted by one or more substituents selected from optionally substituted phenyl), -S 2 R t2, -C OR t3, -C N(R t4)R t5 and inorganic metal salts; R t1 represents C 1-6 alkyl or optionally substituted phenyl; R t2 represents optionally substituted phenyl; R t3 represents optionally substituted phenyl or C 1-6 (e.g. C 1-4) alkyl; R t4 and R t5 independently represent hydrogen, C 1-6 alkyl, optionally substituted phenyl or -C R t6; R t6 represents C 1-6 alkyl or optionally substituted phenyl; R x1, R x2, R x3, R x6, R x7, R x8, R x9, R x10, R a1, R a3, R a6, R a7, R a8, R a9, R a10, R b1, R b2 and R b3 independently represent hydrogen or C 1-6 alkyl optionally substituted by one or more halo atoms; R x4, R x5, R x11, R x12, R a4, R a5, R a11 and R a12 independently represent C 1-6 alkyl optionally substituted by one or more halo atoms; and wherein optional substituents on phenyl groups are selected from halo, -NO 2, -OH and/or -OC 1-6 alkyl, or a salt or solvate thereof.