Biphenyl derivatives and their use in treating hepatitis C

A compound which is a biphenyl derivative of formula (I), a pharmaceutically acceptable salt, or a mixture thereof

• wherein:
• Ri is -A1-L1-A1′;
• A1 is a non-fused, unsubstituted phenyl group;
• L1 is —CH2— or —CH2CH2—;
• A1′ is a piperazinyl group which is substituted by an unsubstituted —SO2—(C1-C4 alkyl);
• A is —CONH—;
• B is —NH—CO—NH—, —NH—CO— or —CO—NH—;
• R2 and R3 are the same or different and each represent C1-C4 alkyl, C1-C4 alkoxy, C1-C4 haloalkyl, C1-C4 haloalkoxy or halogen;
• n and m are the same or different and each represent 0 or 1;
• R4 is a C1-C6 alkyl group or a moiety selected from the group consisting of -A4, -L4-A4, -A4-A4′, -L4-A4-A4′, -A4-L4-A4′, -A4-Y4-A4′, -A4-Het4-A4′, -L4-A4-Y4-A4′, -L4-A4-Het4-A4′, -L4-Het4-A4, -L4-Y4-A4, -L4-Y4-Het4-A4, -L4-Het4-Y4-A4, -L4-Y4-Het4-L4′, -A4-Y4-Het4-A4′, -A4-Het4-Y4-A4′, -A4-Het4-L4-A4′, -A4-L4-Het4-A4 ′ and -L4-Het4-L4′,
• each A4, and A4 ′ are the same or different and represent a phenyl, 5- to 10- membered heteroaryl, 5- to 10- membered heterocyclyl or C3-C8 carbocyclyl moiety;
• L4 is a C1-C4 alkylene or a C1-C4 hydroxyalkylene group;
• Y4 is —CO—, —SO— or —S(O)2—;
• L4′ is hydrogen or a C1-C4 alkyl group;
• and
• Het4 is —O—, —S— or —NR′—, wherein R′ is hydrogen or a C1-C4 alkyl group;
• the phenyl, heteroaryl, heterocyclyl and carbocyclyl moieties in R4 are optionally fused to a phenyl, 5- to 10- membered heteroaryl or 5- to 10- membered heterocyclyl ring;
• and
• the phenyl, heteroaryl, heterocyclyl and carbocyclyl moieties in R4 are unsubstituted or substituted by (a) a single unsubstituted substituent selected from —(C1-C2 alkyl)-X1, —CO2R″′, —SO2R″′, —SO2NR′R″′, —CONR′R″′, —NR′—CO—R″′, —NR′—SO2—R″′ and —CO—NR′—(C1-C2 alkyl)—NR′R″′ and/or (b) 1, 2 or 3 unsubstituted substituents selected from —(C1-C2 alkyl)—X2, halogen, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 haloalkyl, C1-C4 haloalkoxy, C1-C4 hydroxyalkyl, hydroxy, cyano and —NR′R″, wherein X1 is —CO2R″′, —NR′-CO2—R″′, —-NR′—S(O)2—R″′ or —SO2NR′R″′, each X2 is the same or different and is cyano or —NR′R″, each R′ and R″ are the same or different and represent hydrogen or C1-C4 alkyl and each R″′ is the same or different and represents C1-C4 alkyl.