Heteroaryl amides useful as inhibitors of voltage-gated sodium channels

1. A compound of formula II″-A4:

or a pharmaceutically acceptable salt thereof, wherein:

Ring B is is selected from:

each R 2 is independently hydrogen:

x is 0-3;

each occurrence of R N is independently selected from hydrogen

each occurrence of R 3 is independently Q-R X ;

each occurrence of R 4 is independently selected from hydrogen, CN, or NO 2 ;

Q is a bond or is a C 1-6 aliphatic chain wherein up to three methylene units of Q are optionally and independently replaced by —NH—, —NR—, —O—, —S—, —CO 2 —, —OC(O)—, —C(O)CO—, —C(O)—, —C(S)—, —C(O)NH—, —C(O)NR—, —C(═N—CN)—, —NHCO—, —NRCO—, —NHC(O)O—, —NRC(O)O—, —SO 2 NH—, —SO 2 NR—, —NHSO 2 —, —NRSO 2 —, —NHC(O)NH—, —NRC(O)NH—, —NHC(O)NR—, —NRC(O)NR, —OC(O)NH—, —OC(O)NR—, —NHSO 2 NH—, —NRSO 2 NH—, —NHSO 2 NR—, —NRSO 2 NR—, —SO— or —SO 2 —; wherein

Q is optionally substituted with 1-3 independent occurrences of R Q ;

each occurrence of R X is independently selected from —R′, halogen, —NO 2 , —CN, —OR′, —SR′, —N(R′) 2 , —NR′C(O)R′, —NR′C(O)N(R′) 2 , —NR′CO 2 R′, —C(O)R′, —CO 2 R′, —OC(O)R′, —C(O)N(R′) 2 , —OC(O)N(R′) 2 , —SOR′, —SO 2 R′, —SO 2 N(R′) 2 , —NR′SO 2 R′, —NR′SO 2 N(R′) 2 , —C(O)C(O)R′, —C(O)CH 2 C(O)R′, —OP(O)(OR′) 2 , —P(O)(OR′) 2 , —PO(OR′)(R′), —P(O)(R′) 2 , or —OP(O)(R′) 2 ;

each occurrence of R is independently selected from hydrogen or a C 1-6 aliphatic group optionally substituted with 1-3 independent occurrences of —R T , -T-Ar 1 , halogen, oxo, thioxo, —OR T , —SR T , —N(R T ) 2 , —NO 2 , —C 1-4 haloalkyl, —C 1-4 haloalkoxy, —CN, —CO 2 R T , —COR T , —CON(R T ) 2 , —OCOR T , —NR T COR T , —SO 2 R T , —SO 2 N(R T ) 2 , or —NR T SO 2 R T ; wherein

each R T is independently hydrogen or unsubstituted C 1-6 aliphatic; or

any two R T groups, on the same substituent or different substituents, together with the atom(s) to which each group is bound, optionally form a 3-8 membered saturated or partially unsaturated monocyclic ring, or a 5-6 membered monocyclic aryl ring having 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur; wherein said monocyclic ring is optionally substituted with 1-3 independent occurrences of —R R , -T-Ar 1 , halogen, oxo, thioxo, —OR R , —SR R , —N(R R ) 2 , —NO 2 , —C 1-4 haloalkyl, —C 1-4 haloalkoxy, —CN, —CO 2 R R , —COR R , CON(R R ) 2 , —OCOR R , —NR R COR R , —SO 2 R R , —SO 2 N(R R ) 2 , or —NR R SO 2 R R ; wherein

each R R is independently hydrogen or unsubstituted C 1-6 aliphatic;

T is (CH 2 ) w ;

w is 0-2;

Ar 1 is selected from a 3-8 membered saturated or partially unsaturated ring, a 5-6 membered aryl ring, a 3-7 membered heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 5-6 membered heteroaryl ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-12 membered saturated, partially unsaturated, or fully unsaturated bicyclic ring system having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; wherein

Ar 1 is optionally substituted with 1-3 independent occurrences of —R W , oxo, thioxo, —CO 2 R W , —OR W , —N(R W ) 2 , —SR W , —NO 2 , halogen, —CN, —C 1-4 haloalkyl, —C 1-4 haloalkoxy, —C(O)N(R W ) 2 , —NR W C(O)R W , —SO 2 R W , —SO 2 N(R W ) 2 , —NR W SO 2 R W , —NR W CON(R W ) 2 , —NR W CO 2 R W , —COR W , —OCOR W , —OCON(R W ) 2 , —SOR W , —NR W SO 2 N(R W ) 2 , —COCOR W , —COCH 2 COR W , —OP(O)(OR W ) 2 , —P(O)(OR W ) 2 , —PO(OR W )(R W ), —P(O)(R W ) 2 , or —OP(O)(R W ) 2 ; wherein

R W is hydrogen or unsubstituted C 1-6 aliphatic;

R Q is selected from halogen, —R S , —N(R S ) 2 , —SR S , —OR S , C 3-10 cycloaliphatic, C 6-10 aryl, 5-10 membered heteroaryl, 5-10 membered heterocyclyl, oxo, thioxo, —C 1-4 haloalkoxy, —C 1-4 haloalkyl, —NO 2 , —CN, —CF 3 , —OCF 3 , —CO 2 R S , —COR S , —OC(O)R S or —NR S C(O)R S ; wherein

R S is hydrogen or unsubstituted C 1-6 aliphatic; or

any two R Q or two R S groups, or any combination of an R Q group with an R S group on the same substituent or different substituents, together with the atom(s) to which each group is bound, optionally form a 3-8 membered saturated or partially unsaturated monocyclic ring, or a 5-6 membered monocyclic aryl ring; each ring having 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur; wherein any of said monocyclic ring is optionally substituted with 1-3 independent occurrences of R O , halogen, oxo, thioxo, —OR O , —SR O , —N(R O ) 2 , —NO 2 , —C 1-4 haloalkyl, —C 1-4 haloalkoxy, —CN, —CO 2 R O , —COR O , —CON(R O ) 2 , —OCOR O , —NR O COR O , —SO 2 R O , —SO 2 N(R O ) 2 , or —NR O SO 2 R O ; wherein

R O is hydrogen or unsubstituted C 1-6 aliphatic;

each occurrence of R′ is independently selected from hydrogen or a C 1-8 aliphatic, C 6-10 aryl, a heteroaryl ring having 5-10 ring atoms, or a heterocyclyl ring having 3-10 ring atoms, or wherein R and R′ taken together with the atom(s) to which they are bound, or two occurrences of R′ taken together with the atom(s) to which they are bound, form a 5-8 membered cycloalkyl, heterocyclyl, aryl, or heteroaryl ring having 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur; wherein said C 1-8 aliphatic, C 6-10 aryl, heteroaryl ring or heterocyclyl ring is optionally substituted with 1-3 independent occurrences of R I , halogen, oxo, thioxo, —OR I , —SR I , —N(R I ) 2 , —NO 2 , —C 1-4 haloalkyl, —C 1-4 haloalkoxy, —CN, —CO 2 R I , —COR I , —CONHR I , —OCOR I , —NR I COR I , —SO 2 R I , —SO 2 N(R I ) 2 , or —NR I SO 2 R I ; wherein

R I is hydrogen or unsubstituted C 1-6 aliphatic.

2. The compound according to claim 1 , wherein ring B is an optionally substituted 6-membered heteroaryl ring.

3. The compound according to claim 2 , wherein ring B is selected from:

4. The compound according claim 1 , wherein ring B is selected from:

5. The compound according to claim 1 , wherein x is 1-3.

6. The compound according to claim 5 , wherein x is 1-3, and each R 3 is independently selected from hydrogen, halogen, CN, CF 3 , NO 2 , or an optionally substituted group selected from C 1-6 aliphatic, C 1-6 cycloaliphatic, C 6-10 aryl, 5-6 membered heteroaryl, 4-7 membered heterocyclyl, aralkyl, —N(R′) 2 , —CH 2 N(R′) 2 , —OR′, —CH 2 OR′, —SR′, —CH 2 SR′, —C(O)R′, —COOR′, —NRCOR′, —CON(R′) 2 , —S(O) 2 R′, or —S(O) 2 N(R′) 2 .

7. The compound according to claim 6 , wherein x is 1-2 and each R 3 is methyl, ethyl, propyl, isopropyl, t-butyl, sec-butyl or an optionally substituted group selected from C 1-6 aliphatic, C 6-10 aryl, 5-6 membered heteroaryl, 4-7 membered heterocyclyl or aralkyl.

8. The compound according to claim 1 , wherein each R 4 is hydrogen.

9. A compound selected from:

10. A pharmaceutical composition comprising a compound of claim 1 , and a pharmaceutically acceptable carrier, adjuvant, or vehicle.

11. The pharmaceutical composition according to claim 10 , further comprising an additional therapeutic agent.

12. A method of treating or lessening the severity in a subject of acute pain, radicular pain, sciatica, back pain, head or neck pain, intractable pain, postsurgical pain, comprising administering an effective amount of a compound according to claim 1 or a pharmaceutically acceptable composition comprising a compound to said subject in need thereof.