A compound of Formula I: or a pharmaceutically acceptable salt thereof, wherein: R 1 is R 2 is C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 haloalkyl, hydroxyl, C 1 -C 6 alkoxy, C 1 -C 6 heteroalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, - C -, -S -, -O-, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, nitro, cyano, wherein each of C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 haloalkyl, C 1 -C 6 alkoxy, C 1 -C 6 heteroalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, -S -, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, is optionally substituted with 1-3 R 3; each R 3 is independently C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, halo, C 1 -C 6 haloalkoxy, hydroxyl, C 1 -C 6 alkoxy, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, cyano, nitro, amido, -S-, -S 2 -, -C -, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl, wherein each of C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, C 1 -C 6 haloalkoxy, C 1 -C 6 alkoxy, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, amido, -S-, -S 2 -, -C -, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl is optionally substituted with 1-3 R 4; and each R 4 is independently C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, C 1 -C 6 haloalkoxy, C 1 -C 6 haloalkyl, heterocycloalkyl, C 6 -C 10 aryl, heteroaryl, C 4 -C 10 cycloalkylalkyl, heterocycloalkylalkyl, C 7 -C 16 arylalkyl, heteroaryl-C 1 -C 6 alkyl, halo, hydroxyl, C 1 -C 6 alkoxy, C 1 -C 6 hydroxyalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 2 -C 8 alkoxyalkoxyl, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, -S-, -S-C 1 -C 6 alkyl, -S 2 -C 1 -C 6 alkyl, sulfonamidyl, amido, urea, sulfonylurea, acyl, -C -C 6 -C 10 aryl, -NHC -C 6 -C 10 aryl, - C NH-C 6 -C 10 aryl, -C OH, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, acyl, nitro, or cyano. R 1 is R 2 is C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 haloalkyl, hydroxyl, C 1 -C 6 alkoxy, C 1 -C 6 heteroalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, - C -, -S -, -O-, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, nitro, cyano, wherein each of C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 haloalkyl, C 1 -C 6 alkoxy, C 1 -C 6 heteroalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, -S -, heterocycloalkyl, heteroaryl, sulfonamidyl, amido, urea, sulfonylurea, acyl, is optionally substituted with 1-3 R 3; each R 3 is independently C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, halo, C 1 -C 6 haloalkoxy, hydroxyl, C 1 -C 6 alkoxy, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, cyano, nitro, amido, -S-, -S 2 -, -C -, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl, wherein each of C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, C 1 -C 6 haloalkoxy, C 1 -C 6 alkoxy, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, amido, -S-, -S 2 -, -C -, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, heterocycloalkyl, phenyl, or naphthyl is optionally substituted with 1-3 R 4; and each R 4 is independently C 1 -C 6 alkyl, C 1 -C 6 heteroalkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, C 1 -C 6 haloalkoxy, C 1 -C 6 haloalkyl, heterocycloalkyl, C 6 -C 10 aryl, heteroaryl, C 4 -C 10 cycloalkylalkyl, heterocycloalkylalkyl, C 7 -C 16 arylalkyl, heteroaryl-C 1 -C 6 alkyl, halo, hydroxyl, C 1 -C 6 alkoxy, C 1 -C 6 hydroxyalkyl, C 6 -C 10 aryloxy, C 7 -C 16 arylalkoxy, C 2 -C 8 alkoxyalkoxyl, amino, C 1 -C 6 alkylamino, C 2 -C 12 dialkylamino, -S-, -S-C 1 -C 6 alkyl, -S 2 -C 1 -C 6 alkyl, sulfonamidyl, amido, urea, sulfonylurea, acyl, -C -C 6 -C 10 aryl, -NHC -C 6 -C 10 aryl, - C NH-C 6 -C 10 aryl, -C OH, -C O-C 1 -C 6 alkyl, -C -C 1 -C 6 alkyl, acyl, nitro, or cyano.