Tetrahydroisoquinoline derivatives

A compound of formula (I), or a pharmaceutically acceptable salt thereof,

• wherein
• R1, R2 and R3 represent independently hydrogen, halogen or cyano;
• or R1, R2 and R3 represent independently C1-6 alkyl or C1-6 alkoxy, either of which groups may be optionally substituted by one or more substituents;
• R4 represents —N═S(O)RaRb, or R4 represents C1-6 alkyl, C1-6 alkoxy, C3-8 cycloalkyl or C3-7heterocycloalkyl, each of these groups which may be optionally substituted by one or more substituents;
• Ra and Rb represent independently C1-6 alkyl, which group may be optionally substituted by one or more substituents;
• or Ra and Rb are linked together to form with the S atom to which they are attached a C3-7 heterocycloalkyl, which group may be optionally substituted by one or more substituents;
• G represents a fused heterocyclic system selected from the groups represented by formula (G1), (G2), (G3), (G4), (G5), and (G6),
• wherein
• the asterisk (*) represents the point of attachment of G to the remainder of the molecule;
• V1 represents CH or N;
• W1 and W2 represent independently CR9R10;
• X represents O or NR11;
• R5 represents halogen or cyano:
• or R5 represents C1-6 alkyl or C1-6 alkoxy, either of which group may be optionally substituted by one or more substituents;
• R6 and R7 represent independently hydrogen, halogen or cyano;
• or R6 and R7 represent independently C1-6alkyl or C1-6 alkoxy, either of these groups which may be optionally substituted by one or more substituents;
• R8 represents hydrogen, halogen or cyano;
• or R8 represents independently C1-6 alkyl, C3-8 cycloalkyl or C1-6 alkoxy, either of these groups which may be optionally substituted by one or more substituents;
• R9 and R10 represent independently hydrogen or halogen;
• or R9 and R10 represent independently C1-6 alkyl, which group may be optionally substituted by one or more substituents;
• and
• R11 represents hydrogen;
• or R11 represents C1-6alkyl, which group may be optionally substituted by one or more substituents.