A compound of formula I: or a pharmaceutically acceptable salt thereof; wherein: Z is -(CH 2) x - wherein x is 1, 2, 3 or 4 or -O-(CH 2) z - wherein z is 2, 3 or 4; each X is independently CH or N; each of R and R 8 are independently H, C 1 -C 3 alkyl or haloalkyl; each R 1 is independently aryl, alkyl, cycloalkyl or haloalkyl, wherein each of said alkyl, cycloalkyl and haloalkyl groups optionally includes O or N heteroatoms in place of a carbon in the chain and two R 1' s on adjacent ring atoms or on the same ring atom together with the ring atom(s) to which they are attached optionally form a 3-8-membered cycle; y is 0, 1, 2, 3 or 4; R 2 is -(alkylene) m -heterocyclo, -(alkylene) m -heteroaryl, -(alkylene) m -NR 3 R 4, -(alkylene) m -C -NR 3 R 4; -(alkylene) m -C -O-alkyl; -(alkylene) m -O-R 5, -(alkylene) m -S n -R 5, or -(alkylene) m -S n -NR 3 R 4 any of which may be optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same atom or adjacent atoms may optionally combine to form a ring; R 3 and R 4 at each occurrence are independently: (i) hydrogen or (ii) alkyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; or R 3 and R 4 together with the nitrogen atom to which they are attached may combine to form a heterocyclo ring optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; R 5 at each occurrence is: (i) hydrogen or (ii) alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance; R 6 is H or C 1-6 alkyl; R x at each occurrence is independently selected from halo, cyano, nitro, oxo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocyclo, aryl, heteroaryl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, and heterocycloalkyl; n is 0, 1 or 2; and m is 0 or 1. Z is -(CH 2) x - wherein x is 1, 2, 3 or 4 or -O-(CH 2) z - wherein z is 2, 3 or 4; each X is independently CH or N; each of R and R 8 are independently H, C 1 -C 3 alkyl or haloalkyl; each R 1 is independently aryl, alkyl, cycloalkyl or haloalkyl, wherein each of said alkyl, cycloalkyl and haloalkyl groups optionally includes O or N heteroatoms in place of a carbon in the chain and two R 1' s on adjacent ring atoms or on the same ring atom together with the ring atom(s) to which they are attached optionally form a 3-8-membered cycle; y is 0, 1, 2, 3 or 4; R 2 is -(alkylene) m -heterocyclo, -(alkylene) m -heteroaryl, -(alkylene) m -NR 3 R 4, -(alkylene) m -C -NR 3 R 4; -(alkylene) m -C -O-alkyl; -(alkylene) m -O-R 5, -(alkylene) m -S n -R 5, or -(alkylene) m -S n -NR 3 R 4 any of which may be optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same atom or adjacent atoms may optionally combine to form a ring; R 3 and R 4 at each occurrence are independently: (i) hydrogen or (ii) alkyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; or R 3 and R 4 together with the nitrogen atom to which they are attached may combine to form a heterocyclo ring optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; (i) hydrogen or (ii) alkyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; or R 3 and R 4 together with the nitrogen atom to which they are attached may combine to form a heterocyclo ring optionally independently substituted with one or more R x groups as allowed by valance, and wherein two R x groups bound to the same or adjacent atom may optionally combine to form a ring; R 5 at each occurrence is: (i) hydrogen or (ii) alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance; (i) hydrogen or (ii) alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclo, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkyl, arylalkyl, or heteroarylalkyl any of which may be optionally independently substituted with one or more R x groups as allowed by valance; R 6 is H or C 1-6 alkyl; R x at each occurrence is independently selected from halo, cyano, nitro, oxo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocyclo, aryl, heteroaryl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, and heterocycloalkyl; n is 0, 1 or 2; and m is 0 or 1.