A compound of the formula II or formula III: wherein each R 1 and R 2 is independently H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, mono- or bicyclic heteroaryl; or R 1 and R 2 taken together with the carbon atom to which they are attached combine to form a C 3 -C 6 cycloalkyl; each R 3 and R 3' is independently H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, mono- or bicyclic heteroaryl; or R 3 and R 3' taken together with the carbon atom to which they are attached combine to form a C 3 -C 6 cycloalkyl; each R 4 and R 5 is independently hydrogen, deuterium, halogen, -OR c, -OC R c, -OC NR c R d, -OC(=N)NR c R d, -OS R c, -OS 2 R c, -OS NR c R d, -OS 2 NR c R d, -SR c, -S R c, -S 2 R c, -S NR c R d, -S 2 NR c R d, -NR c R d, -NR c C R d, -NR c C OR d, -NR c C NR c R d, -NR c C(=N)NR c R d, -NR c S R d, -NR c S 2 R d, -NR c S NR c R d, -NR c S 2 NR c R d, -C R c, -C OR c, -C NR c R d, -C(=N)NR c R d, -PR c R d, -P R c R d, -P 2 R c R d, -P NR c R d, -P 2 NR c R d, -P OR c, -P 2 OR c, -CN, -NO 2, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, or mono- or bicyclic heteroaryl; R 6 is H; each R 7 is independently hydrogen or deuterium; and each R a, R b, R c, and R d is independently selected from the group consisting of H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, and 5- to 7- membered heteroaryl; or a pharmaceutically acceptable salt thereof. each R 1 and R 2 is independently H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, mono- or bicyclic heteroaryl; or R 1 and R 2 taken together with the carbon atom to which they are attached combine to form a C 3 -C 6 cycloalkyl; each R 3 and R 3' is independently H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, mono- or bicyclic heteroaryl; or R 3 and R 3' taken together with the carbon atom to which they are attached combine to form a C 3 -C 6 cycloalkyl; each R 4 and R 5 is independently hydrogen, deuterium, halogen, -OR c, -OC R c, -OC NR c R d, -OC(=N)NR c R d, -OS R c, -OS 2 R c, -OS NR c R d, -OS 2 NR c R d, -SR c, -S R c, -S 2 R c, -S NR c R d, -S 2 NR c R d, -NR c R d, -NR c C R d, -NR c C OR d, -NR c C NR c R d, -NR c C(=N)NR c R d, -NR c S R d, -NR c S 2 R d, -NR c S NR c R d, -NR c S 2 NR c R d, -C R c, -C OR c, -C NR c R d, -C(=N)NR c R d, -PR c R d, -P R c R d, -P 2 R c R d, -P NR c R d, -P 2 NR c R d, -P OR c, -P 2 OR c, -CN, -NO 2, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, or mono- or bicyclic heteroaryl; R 6 is H; each R 7 is independently hydrogen or deuterium; and each R a, R b, R c, and R d is independently selected from the group consisting of H, deuterium, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 6 cycloalkyl, 3- to 7-membered heterocycloalkyl, C 6 -C 10 aryl, and 5- to 7- membered heteroaryl;