A compound of formula, or a pharmaceutically acceptable salt thereof: wherein: L is selected from -NHC -, -C NH-, -NH- and -NHC O-; each occurrence of M is independently selected from -CR a = and -N=; wherein each R a is independently selected from (a) H, (b) halogen and (c) C 1-6 alkyl; V is selected from -CR b R b, -NR c - and -O-; wherein each occurrence of R b is independently selected from (a) H, (b) -OH, (c) halogen and (d) C 1-6 alkyl; and R c is selected from (a) H and (b) C 1-6 alkyl; R 1 is selected from C 1-6 alkyl, C 3-6 cycloalkyl, aryl and 5- or 6-membered heteroaryl; wherein: the C 1-6 alkyl of is optionally substituted with -NH 2; and each of the aryl of and the heteroaryl of is optionally substituted with 1 to 3 substituents independently selected from: (a) halogen, (b) -CN, (c) -NH 2, (d) C 1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from halogen, -OH, -NH 2 and C 3-6 cycloalkyl, (e) -O-C 1-6 alkyl optionally substituted with 1 to 3 halogens and (f) C 3-6 cycloalkyl; each occurrence of R 2 is independently selected from H, -OH, halogen, -CN and C 1-6 alkyl; wherein the C 1-6 alkyl of is optionally substituted with 1 to 3 substituents independently selected from (a) -OH and (b) halogen; R 3 is selected from H and C 1-6 alkyl optionally substituted with (a) halogen or (b) -OH; and R 4 is selected from H, halogen, -CN, C 2-6 alkenyl and C 1-6 alkyl optionally substituted with -OH. L is selected from -NHC -, -C NH-, -NH- and -NHC O-; each occurrence of M is independently selected from -CR a = and -N=; wherein each R a is independently selected from (a) H, (b) halogen and (c) C 1-6 alkyl; V is selected from -CR b R b, -NR c - and -O-; wherein each occurrence of R b is independently selected from (a) H, (b) -OH, (c) halogen and (d) C 1-6 alkyl; and R c is selected from (a) H and (b) C 1-6 alkyl; R 1 is selected from C 1-6 alkyl, C 3-6 cycloalkyl, aryl and 5- or 6-membered heteroaryl; wherein: the C 1-6 alkyl of is optionally substituted with -NH 2; and each of the aryl of and the heteroaryl of is optionally substituted with 1 to 3 substituents independently selected from: (a) halogen, (b) -CN, (c) -NH 2, (d) C 1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from halogen, -OH, -NH 2 and C 3-6 cycloalkyl, (e) -O-C 1-6 alkyl optionally substituted with 1 to 3 halogens and (f) C 3-6 cycloalkyl; the C 1-6 alkyl of is optionally substituted with -NH 2; and each of the aryl of and the heteroaryl of is optionally substituted with 1 to 3 substituents independently selected from: (a) halogen, (b) -CN, (c) -NH 2, (d) C 1-6 alkyl optionally substituted with 1 to 3 substituents independently selected from halogen, -OH, -NH 2 and C 3-6 cycloalkyl, (e) -O-C 1-6 alkyl optionally substituted with 1 to 3 halogens and (f) C 3-6 cycloalkyl; each occurrence of R 2 is independently selected from H, -OH, halogen, -CN and C 1-6 alkyl; wherein the C 1-6 alkyl of is optionally substituted with 1 to 3 substituents independently selected from (a) -OH and (b) halogen; R 3 is selected from H and C 1-6 alkyl optionally substituted with (a) halogen or (b) -OH; and R 4 is selected from H, halogen, -CN, C 2-6 alkenyl and C 1-6 alkyl optionally substituted with -OH.