A compound of formula (I) or a salt thereof ** ** Formula wherein R1 is C1-3alkyl R2 is -NR2aR2a or -OR2b wherein one of R2a or R2a is hydrogen, and R2b or the other of R2a or R2a are selected from C1-6 alkyl, C1-6 haloalkyl, R2cR2cN - C2-6 alkyl, C2-alkyl R2CO -6, carbocyclyl, carbocyclylalkyl C1-4, heterocyclyl and heterocyclylalkyl C1- 4, wherein carbocyclyl groups either or heterocyclyl is optionally substituted with one or more groups selected from halogen, C1-6 alkyl, C1-6 haloalkyl, alkoxy C1-6, C1-6 haloalkoxy, carbonyl, -CO-carbocyclyl, azido, amino, hydroxyl and cyano, or two adjacent groups in either or heterocyclyl carbocyclyl groups, together with the interconnecting atoms form a ring of 5 or 6 elements which ring may contain 1 or 2 heteroatoms independently selected from O, S and N or R2a and R2a with the N atom to which they are attached form a 5-, 6 or 7 members which may optionally contain 1 or 2 heteroatoms independently selected from O, S and N wherein the 5-, 6 or 7 elements may be further optionally substituted with C1-6 alkyl And R2c are independently hydrogen R2c or C1-6 alkyl each R3 is independently selected from hydrogen, hydroxy, halo, C1-6 alkyl, C1-6 haloalkyl, C1-6 alkoxy, C1-6 haloalkoxy, cyano, CF3, -OCF3, -COOR5, - NR6R7 and -aquil aquilC1-4 C1-4 OH R4 is an aromatic carbocyclic group or aromatic heterocyclyl wherein the carbocyclyl group or aromatic heterocyclyl is optionally substituted with one or more groups selected from halo, C1-6 alkyl, C1-6 alkoxy and NR6R7 Aquil C1-4 alkyl group R5 is C1-3alkyl at each occurrence, R6 and R7 are independently hydrogen, C1-6 alkyl or C (O) C1-6 alkyl, or R6 and R7 together with the N atom to which they are attached form a 5-, 6 or 7 elements optionally containing 1 or 2 additional heteroatoms independently selected from O, S and N wherein the 5-, 6 or 7 elements may be further optionally substituted by one or more C1-6 alkyl groups, -C (O) C1-6, alkyl amino or hydroxy n is an integer between 1
