A compound of formula wherein X is selected from S, SO 2, SO, or O; Z is selected from the group consisting of heteroaryl and aryl, wherein any of such heteroaryl and aryl may be optionally substituted by one or more groups selected from (C 1 -C 3)alkyl-, halo and (C 1 -C 6)haloalkyl-; R 1 is H or (C 1 -C 4)alkyl; R 2 is heteroaryl(C 1 -C 4)alkyl-, wherein any of such alkyl and heteroaryl may be optionally substituted by one or more groups selected from (C 1 -C 3)alkyl, (C 1 -C 6)haloalkyl and halo; R is selected from the group consisting of (C 1 -C 6)alkyl-, (C 1 -C 6)alkyl-CN, (C 1 -C 6)haloalkyl, -NR A R B, (C 3 -C 8)heterocycloalkyl-(C 1 -C 6)alkyl-, (C 3 -C 8)heterocycloalkyl-, (C 3 -C 8)heteroaryl-(C 1 -C 6)alkyl-, (C 3 -C 8)cycloalkyl-(C 1 -C 6)alkyl-, (C 3 -C 8)cycloalkyl-, R A O-(C 1 -C 6)alkyl-O-(C 1 -C 6)alkyl-, R A NH-C -(C 1 -C 4)alkyl-, R A R B N-C -(C 1 -C 4)alkyl-, R A O-C (C 1 -C 6)alkyl-, wherein any of such heterocycloalkyl is unsubstituted or substituted by one or more groups selected from OH, -C R a, -C OR A, (C 1 -C 6)haloalkyl, -NH-C R 1, and oxo; any of such cycloalkyl is substituted by one or more groups selected from - C OR A and (C 1 -C 6)haloalkyl-, any of such heteroaryl may be optionally substituted by one or more groups selected from (C 1 -C 6)alkyl-, -OH and (C 3 -C 6)cycloalkyl-; R A and R B are at each occurrence independently H or selected from the group consisting of (C 1 -C 6)alkyl-, (C 1 -C 6)haloalkyl-, -OR 1, -SO 2 R C and (C 3 -C 6)cycloalkyl wherein such cycloalkyl may be optionally substituted by one or more -C OR 1, or alternatively R A and R B may form together with the nitrogen atom to which they are attached a 5 or 6 membered saturated heterocyclic monocyclic ring system optionally containing a further heteroatom which is nitrogen or oxygen, which may be optionally substituted by one or more groups selected from halo and -OR 1; and R C is aryl; with the proviso that R is (C 1 -C 6)alkyl- or unsubstituted (C 3 -C 8)heterocycloalkyl-only when X is S or SO. X is selected from S, SO 2, SO, or O; Z is selected from the group consisting of heteroaryl and aryl, wherein any of such heteroaryl and aryl may be optionally substituted by one or more groups selected from (C 1 -C 3)alkyl-, halo and (C 1 -C 6)haloalkyl-; R 1 is H or (C 1 -C 4)alkyl; R 2 is heteroaryl(C 1 -C 4)alkyl-, wherein any of such alkyl and heteroaryl may be optionally substituted by one or more groups selected from (C 1 -C 3)alkyl, (C 1 -C 6)haloalkyl and halo; R is selected from the group consisting of (C 1 -C 6)alkyl-, (C 1 -C 6)alkyl-CN, (C 1 -C 6)haloalkyl, -NR A R B, (C 3 -C 8)heterocycloalkyl-(C 1 -C 6)alkyl-, (C 3 -C 8)heterocycloalkyl-, (C 3 -C 8)heteroaryl-(C 1 -C 6)alkyl-, (C 3 -C 8)cycloalkyl-(C 1 -C 6)alkyl-, (C 3 -C 8)cycloalkyl-, R A O-(C 1 -C 6)alkyl-O-(C 1 -C 6)alkyl-, R A NH-C -(C 1 -C 4)alkyl-, R A R B N-C -(C 1 -C 4)alkyl-, R A O-C (C 1 -C 6)alkyl-, wherein any of such heterocycloalkyl is unsubstituted or substituted by one or more groups selected from OH, -C R a, -C OR A, (C 1 -C 6)haloalkyl, -NH-C R 1, and oxo; any of such cycloalkyl is substituted by one or more groups selected from - C OR A and (C 1 -C 6)haloalkyl-, any of such heteroaryl may be optionally substituted by one or more groups selected from (C 1 -C 6)alkyl-, -OH and (C 3 -C 6)cycloalkyl-; R A and R B are at each occurrence independently H or selected from the group consisting of (C 1 -C 6)alkyl-, (C 1 -C 6)haloalkyl-, -OR 1, -SO 2 R C and (C 3 -C 6)cycloalkyl wherein such cycloalkyl may be optionally substituted by one or more -C OR 1, or alternatively R A and R B may form together with the nitrogen atom to which they are attached a 5 or 6 membered saturated heterocyclic monocyclic ring system optionally containing a further heteroatom which is nitrogen or oxygen, which may be optionally substituted by one or more groups selected from halo and -OR 1; and R C is aryl; with the proviso that R is (C 1 -C 6)alkyl- or unsubstituted (C 3 -C 8)heterocycloalkyl-only when X is S or SO.