PYRIMIDINE DERIVATIVES

A compound of Formula (I): (see formula I) or a pharmaceutically and/or veterinarily acceptable derivative thereof, wherein R1 is C1-8alkyl, C3-7cycloalkyl-C0-6alkyl- optionally substituted with methyl, alkoxyalkyl containing 3 to 8 carbon atoms, het-C0-6alkyl-, CF3-C1-6alkyl-, CF3OC2-3alkyl-, aryl-C0-6alkyl-or C1-6hydroxyalkyl; R2 is het, provided that the het group contains at least one nitrogen atom or is substituted by a group which contains at least one nitrogen atom; or R2 is (CH2)2NH2, (CH2)2NHCH3, or (CH2)2N(CH3)2; R3 is H or C1-8alkyl; or R3 and R2 together with the nitrogen atom to which they are bound form a 4 to 8 membered non-aromatic heterocyclic group which optionally contains one or more further heteroatoms or groups independently selected from N, O, S, S(O) and S(O)2, wherein the heterocyclic group is optionally a bridged bicyclic group, a spiro bicyclic group or is optionally fused to a 3-, 4-, 5- or 6- membered carbocyclic group or a 4-, 5- or 6-membered heterocyclic group which contains at least one ring member independently selected from N, O, S, S(O) and S(O)2, and wherein the ring system as a whole is optionally substituted by one or more substituents independently selected from C1-6alkyl, NR6R7, (CH2)a C3-7cycloalkyl, alkoxyalkyl containing 2 to 8 carbon atoms, (CH2)b het1, (CH2)c CF3, (CH2)y OCF3, (CH2)d aryl and C1-6hydroxyalkyl, provided that the ring system as a whole contains at least two nitrogen atoms or contains one nitrogen atom and is substituted by a group which contains at least one nitrogen atom; R4 is H; or R1 and R4 together with the nitrogen atom to which they are bound form a 4 to 8 membered non-aromatic heterocyclic group which optionally contains one or more further heteroatoms or groups independently selected from N, O, S, S(O) and S(O)2, wherein the heterocyclic group is optionally a bridged bicyclic group or is optionally fused to a 3-, 4-, 5- or 6- membered carbocyclic group or a 4-, 5- or 6-membered heterocyclic group which contains at least one ring member independently selected from N, O, S, S(O) and S(O)2, and wherein the ring system as a whole is optionally substituted by one or more substituents independently selected from C1-6alkyl, fluoro, NR9R10, (CH2)e C3-7cycloalkyl, alkoxyalkyl containing 2 to 8 carbon atoms, (CH2)f het1, (CH2)g CF3, (CH2),OCF3, (CH2)h aryl and C1-6hydroxyalkyl; R5 is H or NR11R12; R6 and R7 are each independently selected from H, C1-6alkyl and (CH2)j C3-7cycloalkyl; or R6 and R7,