A compound of formula: or a salt, solvate or stereoisomer thereof, wherein: Y and Z are each independently C or N, when Y is N, R 1 is a lone pair and when Z is N, R 4 is a lone pair; R 1., R 2, R 3, R 4, R 5, R 6, R 7 are each independently selected from the group consisting of: H, halogen, alkoxy, OR A, SR A, S(=O)(=O)-R A, SO 2 NHR A, COOR B, OC R B, NR A R B, OP (OR A) 2, NHC R A, CONR A R B, NO 2, CN, substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 2 -C 6 alkynyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl, wherein the substituted C 1 -C 6 alkyl, the C 2 -C 6 substituted alkenyl, the substituted C 2 -C 6 alkynyl, the substituted aryl, the substituted heteroaryl are each independently substituted by one or more substituents selected from the group consisting of: halogen, substituted or unsubstituted phenyl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and CONR A R B; A is the dashed line represents an optional double bond, X is R8 is selected from the group consisting of: H, substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 2 -C 6 alkynyl and substituted or unsubstituted aryl, wherein the substituted C 1 -C 6 alkyl, the substituted C 2 -C 6 alkenyl, the substituted C 2 -C 6 alkynyl or the substituted aryl are each independently substituted by one or more substituents selected from the group consisting of: halogen, substituted or unsubstituted phenyl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and CONR A R B; R A and R B are each independently selected from: H, C 1 -C 6 alkyl, unsubstituted or substituted aralkyl, haloalkyl, or R A and R B together with the nitrogen, sulfur, or oxygen to which they are attached, form a 4-7 membered saturated or partially unsaturated ring optionally containing one or more additional heteroatoms independently selected from N, S and O the ring being optionally substituted by one, two or more groups independently selected from halogen, C 1 -C 6 alkyl, haloalkyl, OH and alkoxy; B and C are each independently selected from: H, unsubstituted or substituted C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, and unsubstituted or substituted phenyl; wherein the substituted C 1 -C 10 alkyl or the substituted phenyl are independently substituted by one or more substituents selected from substituted or unsubstituted phenyl, halogen, C 3 -C 10 cycloalkyl, C 3 -C 10 heterocycloalkyl, substituted or unsubstituted heteroaryl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and COONR A R B; provided that compounds: are excluded. Y and Z are each independently C or N, when Y is N, R 1 is a lone pair and when Z is N, R 4 is a lone pair; R 1., R 2, R 3, R 4, R 5, R 6, R 7 are each independently selected from the group consisting of: H, halogen, alkoxy, OR A, SR A, S(=O)(=O)-R A, SO 2 NHR A, COOR B, OC R B, NR A R B, OP (OR A) 2, NHC R A, CONR A R B, NO 2, CN, substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 2 -C 6 alkynyl, substituted or unsubstituted aryl and substituted or unsubstituted heteroaryl, wherein the substituted C 1 -C 6 alkyl, the C 2 -C 6 substituted alkenyl, the substituted C 2 -C 6 alkynyl, the substituted aryl, the substituted heteroaryl are each independently substituted by one or more substituents selected from the group consisting of: halogen, substituted or unsubstituted phenyl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and CONR A R B; A is the dashed line represents an optional double bond, X is R8 is selected from the group consisting of: H, substituted or unsubstituted C 1 -C 6 alkyl, substituted or unsubstituted C 2 -C 6 alkenyl, substituted or unsubstituted C 2 -C 6 alkynyl and substituted or unsubstituted aryl, wherein the substituted C 1 -C 6 alkyl, the substituted C 2 -C 6 alkenyl, the substituted C 2 -C 6 alkynyl or the substituted aryl are each independently substituted by one or more substituents selected from the group consisting of: halogen, substituted or unsubstituted phenyl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and CONR A R B; R A and R B are each independently selected from: H, C 1 -C 6 alkyl, unsubstituted or substituted aralkyl, haloalkyl, or R A and R B together with the nitrogen, sulfur, or oxygen to which they are attached, form a 4-7 membered saturated or partially unsaturated ring optionally containing one or more additional heteroatoms independently selected from N, S and O the ring being optionally substituted by one, two or more groups independently selected from halogen, C 1 -C 6 alkyl, haloalkyl, OH and alkoxy; B and C are each independently selected from: H, unsubstituted or substituted C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 2 -C 10 alkynyl, and unsubstituted or substituted phenyl; wherein the substituted C 1 -C 10 alkyl or the substituted phenyl are independently substituted by one or more substituents selected from substituted or unsubstituted phenyl, halogen, C 3 -C 10 cycloalkyl, C 3 -C 10 heterocycloalkyl, substituted or unsubstituted heteroaryl, OR A, COOR B, OC R B, NR A R B, OP (OR A) 2, OC NR A R B, NHC OR A, NHC R A and COONR A R B; provided that compounds: are excluded.