A compound of structural formula I: or a pharmaceutically acceptable salt thereof; wherein A is phenyl; B is selected from the group consisting of: phenyl, and pyridyl; R 1 is selected from the group consisting of: halogen, -CN, -C 1-6 alkyl, -(CH 2) r OC 1-6 alkyl, -(CH 2) r -C 3-6 cycloalkyl, and -(CH 2) r -O-(CH 2) r -C 3-6 cycloalkyl, wherein each CH 2, -C 1-6 alkyl, -OC 1-6 alkyl and -C 3-6 cycloalkyl is unsubstituted or substituted with one to four substituents selected from halogen, -C 1-6 alkyl and -(CH 2) v -C 3-6 cycloalkyl; R 2 is halogen; each R 3 when present is independently selected from the group consisting of: halogen, -CN, -C 1-6 alkyl, and -(CH 2) u -C 3-6 cycloalkyl, wherein each CH 2, C 1-6 alkyl and C 3-6 cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen; R 4 is selected from the group consisting of: -(CH 2)pC 3-6 cycloalkyl, -(CH 2)pC 3-6 cycloalkyl, -(CH 2)p-C 2-10 cycloheteroalkyl, aryl, and heteroaryl, wherein R 4 is unsubstituted or substituted with one, two, three, four or five substituents selected from R 5; R 5 is selected from the group consisting of: -(CH 2) s halogen, -C 1-6 alkyl, -(CH 2) s- O-C 1-6 alkyl, -(CH 2) s OH, -(CH 2) s CN, -(CH 2) s SO 2 C 1-6 alkyl, -(CH 2) s SO 2 -(CH 2) t -C 3-6 cycloalkyl, -CF 3, -OCHF 2, -OCF 3, -SCH 3, -NH 2, oxo, -NHSO 2 C 1-6 alkyl, -NHCOC 1-6 alkyl, -NH(C 1-6 alkyl), and -N(C 1-6 alkyl) 2, wherein each CH 2, C 1-6 alkyl and C 3-6 cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen, C 1-6 alkyl, and -(CH 2) w OH; m is 0, 1, 2 or 3; n is 1 or 2; p is 0, 1, 2, 3 or 4; r is 0, 1, 2 or 3; s is 0, 1, 2 or 3; t is 0, 1, 2 or 3; u is 0, 1, 2 or 3; v is 0, 1, 2 or 3; and w is 0, 1, 2 or 3. A is phenyl; B is selected from the group consisting of: phenyl, and pyridyl; phenyl, and pyridyl; R 1 is selected from the group consisting of: halogen, -CN, -C 1-6 alkyl, -(CH 2) r OC 1-6 alkyl, -(CH 2) r -C 3-6 cycloalkyl, and -(CH 2) r -O-(CH 2) r -C 3-6 cycloalkyl, wherein each CH 2, -C 1-6 alkyl, -OC 1-6 alkyl and -C 3-6 cycloalkyl is unsubstituted or substituted with one to four substituents selected from halogen, -C 1-6 alkyl and -(CH 2) v -C 3-6 cycloalkyl; halogen, -CN, -C 1-6 alkyl, -(CH 2) r OC 1-6 alkyl, -(CH 2) r -C 3-6 cycloalkyl, and -(CH 2) r -O-(CH 2) r -C 3-6 cycloalkyl, R 2 is halogen; each R 3 when present is independently selected from the group consisting of: halogen, -CN, -C 1-6 alkyl, and -(CH 2) u -C 3-6 cycloalkyl, wherein each CH 2, C 1-6 alkyl and C 3-6 cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen; halogen, -CN, -C 1-6 alkyl, and -(CH 2) u -C 3-6 cycloalkyl, R 4 is selected from the group consisting of: -(CH 2)pC 3-6 cycloalkyl, -(CH 2)pC 3-6 cycloalkyl, -(CH 2)p-C 2-10 cycloheteroalkyl, aryl, and heteroaryl, wherein R 4 is unsubstituted or substituted with one, two, three, four or five substituents selected from R 5; -(CH 2)pC 3-6 cycloalkyl, -(CH 2)pC 3-6 cycloalkyl, -(CH 2)p-C 2-10 cycloheteroalkyl, aryl, and heteroaryl, R 5 is selected from the group consisting of: -(CH 2) s halogen, -C 1-6 alkyl, -(CH 2) s- O-C 1-6 alkyl, -(CH 2) s OH, -(CH 2) s CN, -(CH 2) s SO 2 C 1-6 alkyl, -(CH 2) s SO 2 -(CH 2) t -C 3-6 cycloalkyl, -CF 3, -OCHF 2, -OCF 3, -SCH 3, -NH 2, oxo, -NHSO 2 C 1-6 alkyl, -NHCOC 1-6 alkyl, -NH(C 1-6 alkyl), and -N(C 1-6 alkyl) 2, wherein each CH 2, C 1-6 alkyl and C 3-6 cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen, C 1-6 alkyl, and -(CH 2) w OH; -(CH 2) s halogen, -C 1-6 alkyl, -(CH 2) s- O-C 1-6 alkyl, -(CH 2) s OH, -(CH 2) s CN, -(CH 2) s SO 2 C 1-6 alkyl, -(CH 2) s SO 2 -(CH 2) t -C 3-6 cycloalkyl, -CF 3, -OCHF 2, -OCF 3, -SCH 3, -NH 2, oxo, -NHSO 2 C 1-6 alkyl, -NHCOC 1-6 alkyl, -NH(C 1-6 alkyl), and -N(C 1-6 alkyl) 2, m is 0, 1, 2 or 3; n is 1 or 2; p is 0, 1, 2, 3 or 4; r is 0, 1, 2 or 3; s is 0, 1, 2 or 3; t is 0, 1, 2 or 3; u is 0, 1, 2 or 3; v is 0, 1, 2 or 3; and w is 0, 1, 2 or 3.