A compound having formula A-I: or a salt thereof; wherein: G 1 is hydrogen, R', C R', C R', S R', S 2 R', Si(CH 3) 2 R', P (OR') 3, P (OR') 3, or B(OR') 2; G 2 is halo, CN, CF 3, isopropyl, or phenyl wherein said isopropyl or phenyl is optionally substituted with up to 3 substituents independently selected from WR W; G 3 is an isopropyl or a C 3 -C 10 cycloaliphatic ring, wherein said G 3 is optionally substituted with up to 3 substituents independently selected from WR W; provided that when G 1 is methyl, G 3 is tert-butyl, then G 2 is not 2-amino-4-methoxy-5- tert -butylphenyl; W is a bond or is an optionally substituted C 1 -C 6 alkylidene chain wherein up to two methylene units of W are optionally and independently replaced by -CO-, -CS-,-COCO-, -CONR'-, -CONR'NR'-, -CO 2 -, -OCO-, -NR'CO 2 -, -O-, -NR'CONR'-, -OCONR'-, -NR'NR', -NR'NR'CO-, -NR'CO-, -S-, -SO, -SO 2 -, -NR'-, -SO 2 NR'-, NR'SO 2 -, or -NR'SO 2 NR'-; R W is independently R', halo, NO 2, CN, CF 3, or OCF 3; and R' is independently selected from hydrogen or an optionally substituted group selected from a C 1 -C 8 aliphatic group, a 3-8-membered saturated, partially unsaturated, or fully unsaturated monocyclic ring having 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-12 membered saturated, partially unsaturated, or fully unsaturated bicyclic ring system having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; or two occurrences of R' are taken together with the atom(s) to which they are bound to form an optionally substituted 3-12 membered saturated, partially unsaturated, or fully unsaturated monocyclic or bicyclic ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. G 1 is hydrogen, R', C R', C R', S R', S 2 R', Si(CH 3) 2 R', P (OR') 3, P (OR') 3, or B(OR') 2; G 2 is halo, CN, CF 3, isopropyl, or phenyl wherein said isopropyl or phenyl is optionally substituted with up to 3 substituents independently selected from WR W; G 3 is an isopropyl or a C 3 -C 10 cycloaliphatic ring, wherein said G 3 is optionally substituted with up to 3 substituents independently selected from WR W; provided that when G 1 is methyl, G 3 is tert-butyl, then G 2 is not 2-amino-4-methoxy-5- tert -butylphenyl; W is a bond or is an optionally substituted C 1 -C 6 alkylidene chain wherein up to two methylene units of W are optionally and independently replaced by -CO-, -CS-,-COCO-, -CONR'-, -CONR'NR'-, -CO 2 -, -OCO-, -NR'CO 2 -, -O-, -NR'CONR'-, -OCONR'-, -NR'NR', -NR'NR'CO-, -NR'CO-, -S-, -SO, -SO 2 -, -NR'-, -SO 2 NR'-, NR'SO 2 -, or -NR'SO 2 NR'-; R W is independently R', halo, NO 2, CN, CF 3, or OCF 3; and R' is independently selected from hydrogen or an optionally substituted group selected from a C 1 -C 8 aliphatic group, a 3-8-membered saturated, partially unsaturated, or fully unsaturated monocyclic ring having 0-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-12 membered saturated, partially unsaturated, or fully unsaturated bicyclic ring system having 0-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur; or two occurrences of R' are taken together with the atom(s) to which they are bound to form an optionally substituted 3-12 membered saturated, partially unsaturated, or fully unsaturated monocyclic or bicyclic ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.