Methods for treating Huntington's disease

A compound, or form thereof, selected from the group consisting of:

• 2-{6-[(1R,5S)-8-azabicyclo[3.2.1]oct-3-yl(methyl)amino]pyridazin-3-yl}-5-(1H-pyrazol-4-yl)phenol,
• 2-[6-((1R,5S)-8-azabicyclo[3.2.1]oct-3-ylamino)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 5-(1H-pyrazol-4-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)amino]pyridazin-3-yl}phenol,
• 5-(1-methyl-1H-pyrazol-4-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 2-[6-((1R,5S)-8-azabicyclo[3.2.1]oct-3-yloxy)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 5-(5-methyl-1H-pyrazol-4-yl)-2-{6-[methyl(2,2,6,6-tetramethylpiperidin-4-yl)amino]pyridazin-3-yl}phenol,
• 5-(1H-imidazol-1-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 5-(5-methyl-1H-pyrazol-4-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 2-{6-[methyl(2,2,6,6-tetramethylpiperidin-4-yl)amino]pyridazin-3-yl}-5-(4-nitro-1H-pyrazol-1-yl)phenol,
• 6-[2-methoxy-4-(4-nitro-1H-pyrazol-1-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 5-(4-amino-1H-pyrazol-1-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 2-[6-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 5-(4-nitro-1H-pyrazol-1-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 5-(1H-pyrazol-4-yl)-2-[6-(1,2,3,6-tetrahydropyridin-4-yl)pyridazin-3-yl]phenol,
• 2-[6-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 2-{6-[methyl(piperidin-4-yl)amino]pyridazin-3-yl}-5-(1H-pyrazol-4-yl)phenol,
• 2-[6-(piperidin-4-ylamino)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 6-[2,5-difluoro-4-(1H-pyrazol-4-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 2-[6-(8-azabicyclo[3.2.1]oct-2-en-3-yl)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 6-[2,3-difluoro-4-(1H-pyrazol-4-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 3-[2,5-difluoro-4-(1H-pyrazol-4-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 2-[6-(piperidin-4-yloxy)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 2-{6-[(1R,5S)-8-azabicyclo[3.2.1]oct-3-ylamino]pyridazin-3-yl}-5-(1H-pyrazol-4-yl)phenol,
• 6-[2-methoxy-6-(1H-pyrazol-4-yl)pyridin-3-yl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 3-[4-(1H-pyrazol-4-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 2-{6-[(2,6-dimethylpiperidin-4-yl)oxy]pyridazin-3-yl}-5-(1H-pyrazol-4-yl)phenol,
• 3-[2-fluoro-4-(1H-pyrazol-4-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 3-[4-(i-methyl-1H-pyrazol-4-yl)thiophen-2-yl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 2-[6-(2,7-diazaspiro[3.5]non-2-yl)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 3-fluoro-4-{6-[methyl(2,2,6,6-tetramethylpiperidin-4-yl)amino]pyridazin-3-yl}phenol,
• 2-{6-[(2,6-dimethylpiperidin-4-yl)oxy]pyridazin-3-yl}-5-(1H-pyrazol-1-yl)phenol,
• N-methyl-6-(2-methyl-2H-indazol-5-yl)-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 2-methyl-5-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}-2H-indazole,
• 3-(4-chloro-2-methoxyphenyl)-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• N-methyl-6-(2-methylpyrazolo[1,5-a]pyridin-3-yl)-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 6-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}imidazo[1,2-a]pyridine,
• 3-[2-methoxy-4-(1H-pyrazol-1-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 3-[5-(1H-pyrazol-4-yl)thiophen-2-yl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 3-[5-(1-methyl-1H-pyrazol-4-yl)thiophen-2-yl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 3-[4-(1H-pyrazol-4-yl)thiophen-2-yl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 5-(3,5-dimethyl-1H-pyrazol-4-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 6-[2-fluoro-4-(1H-pyrazol-4-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 3-methoxy-4-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol,
• 3-[2-methoxy-4-(4-nitro-1H-pyrazol-1-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 4-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}benzene-1,3-diol,
• 6-[2-chloro-4-(1H-pyrazol-4-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine,
• 2-(1H-pyrazol-4-yl)-4-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}pyrimidin-5-amine,
• 3-[2,6-difluoro-4-(1H-pyrazol-4-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine,
• 2-[6-(2,6-diazaspiro[3.4]oct-2-yl)pyridazin-3-yl]-5-(1H-pyrazol-4-yl)phenol,
• 3-{6-[methyl(2,2,6,6-tetramethylpiperidin-4-yl)amino]pyridazin-3-yl}-6-(1H-pyrazol-4-yl)pyridin-2-ol,
• 6-(1H-pyrazol-4-yl)-3-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}pyridin-2-ol,
• N,2,2,6,6-pentamethyl-N-{5-[3-(1H-pyrazol-4-yl)phenoxy]-1,3,4-thiadiazol-2-yl}piperidin-4-amine,
• N,2,2,6,6-pentamethyl-N-{5-[4-(1H-pyrazol-4-yl)phenoxy]-1,3,4-thiadiazol-2-yl}piperidin-4-amine,
• 3-[2-(difluoromethyl)-4-(1H-pyrazol-4-yl)phenyl]-6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazine, and
• 6-[2-(difluoromethyl)-4-(1H-pyrazol-4-yl)phenyl]-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)pyridazin-3-amine;
• wherein the form of the compound is selected from the group consisting of a salt, hydrate, solvate, isotopologue, racemate, enantiomer, diastereomer, stereoisomer, and tautomer form thereof.

A compound of Formula (Ia11):

• or a form thereof, wherein (when present),
• X is selected from O, NR5a, or a bond;
• A is selected from phenyl, thiophenyl, indazolyl, pyridinyl, pyrimidinyl or phenoxy,
• wherein phenyl and phenoxy are each optionally substituted with 1, 2 or 3 substituents each selected from R1a,
• wherein thiophenyl, indazolyl, pyridinyl, pyrimidinyl are each optionally substituted with 1 or 2 substituents each selected from R1a,
• R1a is selected from halogen, hydroxyl, C1-4alkyl, halo-C1-4alkyl, amino, C1-4alkoxy, or heteroaryl,
• wherein heteroaryl is a monocyclic, bicyclic, or polycyclic carbon atom ring structure radical having one or more heteroatoms selected from O, S, and N, optionally substituted with 1 or 2 substituents each selected from R3a;
• wherein when A is phenyl, R1a is not hydroxyl;
• R3a is selected from nitro or C1-4alkyl;
• R4a is C1-4alkyl;
• R5a is hydrogen, C1-4alkyl, or hydroxyl-C1-4alkyl;
• wherein a form of the compound is selected from the group consisting of a salt, hydrate, solvate, isotopologue, racemate, enantiomer, diastereomer, stereoisomer, and tautomer form thereof.

A compound selected from a compound Formula (Ia15) and Formula (Ia18):

• or a form thereof, wherein (when present),
• X is selected from O, NR5a, or a bond;
• B is selected from 1H-pyrazolyl, piperidinyl, 1,2,3,6-tetrahydropyridinyl, (1R,5S)-8-azabicyclo[3.2.1]octyl, 8-azabicyclo[3.2.1]oct-2-enyl, 2,6-diazaspiro[3.4]octyl or 2,7-diazaspiro[3.5]nonyl, each optionally substituted with 1 or 2 substituents each selected from R4a;
• R1a is selected from halogen, hydroxyl, C1-4alkyl, halo-C1-4alkyl, amino, C1-4alkoxy, or heteroaryl,
• wherein heteroaryl is a monocyclic, bicyclic, or polycyclic carbon atom ring structure radical having one or more heteroatoms selected from O, S, and N, optionally substituted with 1 or 2 substituents each selected from R3a;
• wherein R1a is not chloro or pyrazole;
• R3a is selected from nitro or C1-4alkyl;
• and,
• R4a is C1-4alkyl;
• R5a is hydrogen, C1-4alkyl, or hydroxyl-C1-4alkyl;
• wherein a form of the compound is selected from the group consisting of a salt, hydrate, solvate, isotopologue, racemate, enantiomer, diastereomer, stereoisomer, and tautomer form thereof.