A compound of formula I: ** Formula ** or a pharmaceutically acceptable salt thereof, wherein: m is from 0 to 3； X is: -NRa-； and Ra is hydrogen or C1-6 alkyl； R1 is: C1-6 alkyl； C2-6 alkenyl； C2-6 alkynyl； C1-6 haloalkyl； C1-6 alkoxy-C1-6 alkyl； C2-6 hydroxyalkenyl； C1-6 aminoalkyl； C1-6 alkylsulfonyl-C1-6 alkyl； C3-6 cycloalkyl optionally substituted with C1-6 alkyl； C3-6 cycloalkyl-C1-6 alkyl, wherein the C3-6 cycloalkyl portion is optionally substituted with C1-6 alkyl； tetrahydrofuranyl； C1-6 tetrahydrofuranylalkyl； oxetanyl； or oxetanalkyl C1-6； or R1 and Ra together with the atoms to which they are attached form a three to six membered ring that may optionally include an additional heteroatom selected from O, N and S, and which is substituted with oxo, halo or C1-6 alkyl； R2 is: halo； C1-6 alkoxy； cyano； C2-6 alkynyl； C2-6 alkenyl； C1-6 haloalkyl； C1-6 haloalkoxy； C3-6 cycloalkyl, wherein the C3-6 cycloalkyl portion is optionally substituted with C1-6 alkyl； C3-6 cycloalkyl-C1-6 alkyl, wherein the C3-6 cycloalkyl portion is optionally substituted with C1-6 alkyl； tetrahydrofuranyl； C1-6 tetrahydrofuranylalkyl； acetyl； oxetanyl； or oxetanalkyl C1-6； R3 is: -OR4； halo； cyano； C1-6 alkyl； C1-6 haloalkyl； C3-6 cycloalkyl optionally substituted with C1-6 alkyl； C3-6 cycloalkyl-C1-6 alkyl, wherein the C3-6 cycloalkyl portion is optionally substituted with C1-6 alkyl； tetrahydrofuranyl； tetrahydrofuranyl-C 1-6 alkyl； oxetanyl； or oxetanalkyl C1-6； R4 is: C1-6 alkyl； C1-6 haloalkyl； C1-6 alkoxy-C1-6 alkyl； C3-6 cycloalkyl optionally substituted with C1-6 alkyl or halo； C3-6 cycloalkyl-C1-6 alkyl, wherein the C3-6 cycloalkyl portion is optionally substituted with C1-6 alkyl or halo； tetrahydrofuranyl； C1-6 tetrahydrofuranylalkyl； oxetanyl； or oxetanalkyl C1-6； R5 is hydrogen； or C1-6 alkyl； n is 0 or 1； R6 is hydrogen； C1-6 alkyl； C1-6 alkoxy-C1-6 alkyl； C1-6 hydroxyalkyl； C1-6 aminoalkyl； C3-6 cycloalkyl； C3-6 cycloalkyl-C1-6 alkyl； heterocyclyl； or C1-6 heterocyclyl
