A compound of formula: or a pharmaceutically acceptable salt thereof, wherein: R 1 is hydrogen or methyl; R 2 is isopropyl; R 3 is hydrogen or fluoro; R 4, R 5 and R 6 are each independently selected from hydrogen or fluoro; R 7 is-L-NR 8 R 9, wherein L is selected from a direct bond, -(CH 2) m O(CH 2) n - or - CONR 10 (CH 2) p -, wherein said -(CH 2) m O(CH 2) n - and -CONR 10 (CH 2) p - are optionally substituted by one or more R 11; R 8 and R 9 are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, saturated or unsaturated cycloalkyl, and saturated or unsaturated heterocyclyl, wherein said alkyl, alkenyl, alkynyl, saturated or unsaturated cycloalkyl, and saturated or unsaturated heterocyclyl are optionally substituted with one or more R 12; or R 8 and R 9 together with the nitrogen atom to which they are attached form a saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 13, R 10 is selected from the group consisting of hydrogen, alkyl, cycloalkyl, and saturated or unsaturated heterocyclyl which is carbon linked, wherein said heterocyclyl optionally contains one or more additional heteroatoms selected from N, O and S and is optionally substituted with one or more R 13; R 11 is selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, alkoxyl, and saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 13; R 12 is selected from the group consisting of hydrogen, halogen, cyano, nitro, hydroxyl, alkyl, alkenyl, alkynyl, and alkoxy; R 13 is selected from the group consisting of acyl, alkyl, alkenyl, alkynyl, alkoxy, amide, amino, aryl, cyano, cycloalkyl, halogen, haloalkyl, haloalkoxy, heteroaryl, hydroxy, nitro, and -(CH 2) q NR 14 R 15; R 14 and R 15 are each independently selected from the group consisting of hydrogen, alkyl, and cycloalkyl; or R 14 and R 15 together with the nitrogen atom to which they are attached form a saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 16; R 16 is selected from the group consisting of acyl, alkyl, alkenyl, alkynyl, alkoxy, amide, amino, aryl, cyano, cycloalkyl, halogen, haloalkyl, haloalkoxy, heteroaryl, hydroxy, and nitro; m is 0, 1, or 2; n is an integer in the range of 2 to 4; p is an integer in the range of 2 to 4; and q is 0, 1 or 2. R 1 is hydrogen or methyl; R 2 is isopropyl; R 3 is hydrogen or fluoro; R 4, R 5 and R 6 are each independently selected from hydrogen or fluoro; R 7 is-L-NR 8 R 9, wherein L is selected from a direct bond, -(CH 2) m O(CH 2) n - or - CONR 10 (CH 2) p -, wherein said -(CH 2) m O(CH 2) n - and -CONR 10 (CH 2) p - are optionally substituted by one or more R 11; R 8 and R 9 are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, saturated or unsaturated cycloalkyl, and saturated or unsaturated heterocyclyl, wherein said alkyl, alkenyl, alkynyl, saturated or unsaturated cycloalkyl, and saturated or unsaturated heterocyclyl are optionally substituted with one or more R 12; or R 8 and R 9 together with the nitrogen atom to which they are attached form a saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 13, R 10 is selected from the group consisting of hydrogen, alkyl, cycloalkyl, and saturated or unsaturated heterocyclyl which is carbon linked, wherein said heterocyclyl optionally contains one or more additional heteroatoms selected from N, O and S and is optionally substituted with one or more R 13; R 11 is selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl, alkoxyl, and saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 13; R 12 is selected from the group consisting of hydrogen, halogen, cyano, nitro, hydroxyl, alkyl, alkenyl, alkynyl, and alkoxy; R 13 is selected from the group consisting of acyl, alkyl, alkenyl, alkynyl, alkoxy, amide, amino, aryl, cyano, cycloalkyl, halogen, haloalkyl, haloalkoxy, heteroaryl, hydroxy, nitro, and -(CH 2) q NR 14 R 15; R 14 and R 15 are each independently selected from the group consisting of hydrogen, alkyl, and cycloalkyl; or R 14 and R 15 together with the nitrogen atom to which they are attached form a saturated or unsaturated heterocyclyl optionally containing one or more additional heteroatoms selected from N, O and S and optionally substituted with one or more R 16; R 16 is selected from the group consisting of acyl, alkyl, alkenyl, alkynyl, alkoxy, amide, amino, aryl, cyano, cycloalkyl, halogen, haloalkyl, haloalkoxy, heteroaryl, hydroxy, and nitro; m is 0, 1, or 2; n is an integer in the range of 2 to 4; p is an integer in the range of 2 to 4; and q is 0, 1 or 2.