Patent ID: 8471026

Claim:
A compound of formula (IV-a): or a pharmaceutically acceptable salt thereof wherein: one of X 1 and X 2 is CR 1 and the other is N; G is —R 3 , —V 1 —R 3 , —V 1 -L 1 -R 3 , -L 2 -V 1 —R 3 , -L 2 -V 2 —R 3 , —V 1 -L 1 -V 2 —R 3 , or -L 1 -R 3 ; L 1 is unsubstituted or substituted C 1-3 alkylene chain; L 2 is unsubstituted or substituted C 2-3 alkylene chain; V 1 is —C(O)—, —C(S)—, —C(O)—N(R 4a )—, —C(O)—O—, —S(O) 2 —, or —SO 2 —N(R 4a )—; V 2 is —N(R 4a )—, —N(R 4a )—C(O)—, —N(R 4a )—SO 2 —, —SO 2 —N(R 4a )—, —SO 2 —, —C(O)—, —C(O)—O—, —O—C(O)—, —O—, —S—, —N(R 4a )—C(O)—N(R 4a )—, —N(R 4a )—C(O)—O—, —O—C(O)—N(R 4a )—, or —N(R 4a )—SO 2 —N(R 4a )—; R 3 is unsubstituted or substituted C 1-6 aliphatic, unsubstituted or substituted 3-10-membered cycloaliphatic, unsubstituted or substituted 4-10-membered heterocyclyl having 1-4 heteroatoms independently selected from nitrogen, oxygen, and sulfur, unsubstituted or substituted 6-10-membered aryl, or unsubstituted or substituted 5-10-membered heteroaryl having 1-5 heteroatoms independently selected from nitrogen, oxygen, and sulfur; and each occurrence of R 4a is independently hydrogen, or unsubstituted or substituted C 1-4 aliphatic.