Biphenyl compounds useful as muscarinic receptor antagonists

A compound of formula I:

• wherein:
• a is 0 or an integer of from 1 to 5;
• each R1 is independently selected from —C1-5alkyl, —C2-5alkenyl, —C2-5alkynyl, —C3-6cycloalkyl, -cyano, -halo, —OR1a, —C(O)OR1b, —SR1c, —S(O)R1d, —S(O)2R1e, —NR1fR1g, —NR1hS(O)2R1i, and —NR1jC(O)R1k;
• where each of R1a-1k is independently —H, —C1-5alkyl or phenyl-C1-5alkyl;
• b is 0 or an integer of from 1 to 4;
• each R2 is independently selected from —C1-5alkyl, —C2-5alkenyl, —C2-5alkynyl, —C3-6cycloalkyl, -cyano, -halo, —OR2a, —C(O)OR2b, —SR2c, —S(O)R2d, —S(O)2R2e, —NR2fR2g, —NR2hS(O)2R2i, and —NR2jC(O)R2k;
• where each of R2a-2k is independently —H, —C1-5alkyl or -phenyl-C1-5alkyl;
• W is —O— or —NWa—, where Wa is —H or —C1-5alkyl;
• c is 0 or an integer from 1 to 5;
• each R3 independently is —C1-5alkyl or two R3 groups are joined to form C1-3alkylene, C2-3alkenylene or oxiran-2,3-diyl;
• m is 0 or 1;
• Z is selected from —C(O)N(R4)— and —N(R4)C(O)—, where R4 is selected from —H, —C1-5alkyl, and —C3-5cycloalkyl;
• s is 0, 1 or 2;
• Ar is a phenylene substituted with (R5)q where q is 0 or an integer from 1 to 4 and each R5 is independently selected from -halo, —OH, —C1-5alkyl, and —C1-5alkoxy;
• t is 0, 1 or 2;
• R6 and R7 are taken together to form:
• or
• optionally substituted with one to three —C1-5alkyl groups, or
• where:
• d is 1 or 2;
• e is 0, 1 or 2;
• f is 0, 1, 2 or 3;
• R8 is selected from —C1-5alkyl and ═O;
• R9 is selected from —H, —C1-5alkyl, hydroxyphenyl, heteroaryl, and —X9R9a;
• where X9 is selected from —C1-5alkylene, —C(O)—, —C1-5alkylene-C(O)—, —C(O)—C1-5alkylene, —S(O2)—, —C1-5alkylene-S(O2)—, and —S(O2)—C1-5alkylene;
• and R9a is selected from —H, —OH, —C1-5alkyl, —C1-5alkoxy, aryl, heteroaryl, heterocyclyl, and —NR9bR9c, where R9b and R9c are independently —H or —C1-5alkyl;
• wherein each alkyl and alkoxy group in R1, R1a-1k, R2, R2a-2k, R5, R8, R9, and R9a-c is optionally substituted with 1 to 5 fluoro substituents;
• or a pharmaceutically acceptable salt or stereoisomer thereof.