Methods of synthesizing thyroid hormone analogs and polymorphs thereof

Abstract

To provide methods of synthesis of pyridazinone compounds as thyroid hormone analogs and their prodrugs.SOLUTION: A synthesis method comprises (a) contacting R1MgX or R1 Li with a compound of Formula (I) to form a compound of Formula (II), and then converting it to a compound of Formula (III). In the formulas, R1 is isopropyl or isopropenyl, X is halo, and R2 is H or an amine protecting group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61 / 702,137, filed September 17, 2012, and U.S. Provisional Patent Application No. 61 / 790,432, filed March 15, 2013, each of which is incorporated herein by reference in its entirety. [Background technology]

[0002] The contents of this text file named "41245-522001WO_ST25.txt", which was created on September 16, 2013 and is 4KB in size, are incorporated herein by reference.

[0003] Thyroid hormones are essential for normal growth and development and for maintaining metabolic homeostasis (Paul M. Yen, Physiological reviews, Vol. 81(3): pp. 1097-1126 (2001)). Circulating levels of thyroid hormones are tightly regulated by a feedback mechanism in the hypothalamus / pituitary / thyroid (HPT) axis. Thyroid dysfunction, leading to hypothyroidism or hyperthyroidism, clearly demonstrates the profound effects of thyroid hormones on cardiac function, body weight, metabolism, metabolic rate, body temperature, cholesterol, bone, muscle, and behavior.

[0004] The biological actions of thyroid hormones are mediated by thyroid hormone receptors (TRs or THRs) (MA Lazar, Endocrine Reviews, Vol. 14, pp. 348-399 (1993)). TRs belong to a superfamily of nuclear receptors. They form heterodimers with retinoid receptors, which act as ligand-inducible transcription factors. TRs contain ligand-binding, DNA-binding, and amino-terminal domains and regulate gene expression through interactions with DNA response elements and various nuclear coactivators and corepressors. Thyroid hormone receptors are derived from two distinct genes, α and β. These individual gene products generate multiple forms of each receptor through alternative RNA processing. The major thyroid receptor isoforms are α1, α2, β1, and β2. Thyroid hormone receptors α1, β1, and β2 bind thyroid hormones. It has been shown that thyroid hormone receptor subtypes may differ in their contribution to specific biological responses. Recent studies suggest that TRβ1 plays an important role in regulating TRH (thyrotropin-releasing hormone) and thyroid hormone action in the liver. TRβ2 plays an important role in regulating TSH (thyroid-stimulating hormone) (Abel et al., J. Clin. Invest., Vol. 104: pp. 291-300 (1999)). TRβ1 also plays an important role in regulating heart rate (B. Gloss et al., Endocrinology, Vol. 142: pp. 544-550 (2001); C. Johansson et al., Am. J. Physiol., Vol. 275: pp. R640-R646 (1998)).

[0005] The synthesis of thyroid hormone analogs with high thyroid hormone receptor β selectivity and / or tissue selectivity is being explored. Such thyroid hormone analogs are expected to result in desirable reductions in body weight, lipids, cholesterol, and lipoproteins without significantly affecting cardiovascular function or the normal function of the hypothalamus / pituitary / thyroid axis (see, e.g., Joharapurkar et al., J. Med. Chem., 2012, 55(12), pp. 5649-5675). The development of thyroid hormone analogs that maintain the beneficial effects of thyroid hormone but lack the undesirable effects of hyperthyroidism and hypothyroidism would open new avenues for the treatment of patients with metabolic diseases such as obesity, hyperlipidemia, hypercholesterolemia, and diabetes, as well as other disorders and diseases such as fatty liver disease, NASH, atherosclerosis, cardiovascular disease, hypothyroidism, thyroid cancer, thyroid disease, thyroid hormone insensitivity, and related disorders and diseases. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Paul M.Yen,Physiological reviews,Vol.81(3):pp.1097-1126(2001) [Non-patent document 2] MALazar, Endocrine Reviews, Vol. 14: pp. 348-399 (1993) [Non-patent document 3] Abel et.al.,J.Clin.Invest.,Vol 104:pp.291-300(1999) [Non-patent document 4] B.Gloss et.al.Endocrinology,Vol.142:pp.544-550(2001) [Non-Patent Document 5] C.Johansson et.al.,Am.J.Physiol.,Vol.275:pp.R640-R646(1998) [Non-patent document 6] Joharapurkar et al., J.Med.Chem.,2012,55(12),pp 5649-5675. Summary of the Invention [Problem to be solved by the invention]

[0007] In one aspect, the present invention provides methods for synthesizing thyroid hormone analogs, such as pyridazinone compounds, and their prodrugs. An ideal method for synthesizing thyroid hormone analogs and their prodrugs would provide, for example, the resulting compounds in high purity and high yield. The present invention aims to provide one or more of these desirable features. [Means for solving the problem]

[0008] The present disclosure relates to a synthetic method that can be used to prepare 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one ("Intermediate 7"), a compound useful as an intermediate for the preparation of pyridazinone compounds as thyroid hormone analogs, the method comprising: (a)R 1 MgX or R 1 Li is reacted with the formula (I):

[0009] [ka] and contacting the compound of formula (II):

[0010] [ka] (wherein R 1 is isopropyl or isopropenyl, X is halo, and R 2 is H or an amine protecting group; (b)R 1 is isopropenyl, in the presence of a base, or 1 is isopropyl, the compound of formula (II) can be reacted with the compound of formula (III):

[0011] [ka] The method includes converting the compound of formula (I) into a compound of formula (II).

[0012] In step (a), the solvent can be an aprotic organic solvent such as THF, diethyl ether, toluene, or dioxane, the reaction temperature can be 0 to 60°C, 20 to 50°C, 30 to 45°C, or 35 to 45°C, the reaction time can be 10 minutes to 10 hours, 1 to 8 hours, or 3 to 5 hours, and the Grignard reagent (R 1 The amount of MgX) can be 3 to 10 equivalents or 3 to 6 equivalents of the compound of formula (I).

[0013] In step (b), the compound of formula (II) is isomerized using a base. The base can be an organic base or an inorganic base. Examples of bases include, but are not limited to, triethylamine, pyridine, KOH, NaOH, and carbonates. The isomerization can also be carried out under other conditions, such as acid treatment or heating in an aprotic solvent.

[0014] Furthermore, in step (b), the oxidizing agent is not particularly limited, and for example, a solution of bromine in acetic acid or propionic acid can be used.

[0015] Examples of amine protecting groups include, but are not limited to, substituted alkyl groups, acyl groups (e.g., benzoyl or acetyl groups), and silyl groups. Hydroxy and amine protecting groups are described in T.W. Greene and P.G.M. Buts, Protective Groups in Organic Synthesis, 2d. Ed., John Wiley and Sons (1991).

[0016] In one embodiment, R 1 is isopropenyl, X is Br, and R 1Step (a) is carried out by contacting MgX with a compound of formula (I). The solvent used in this reaction can be THF, and the volume to weight ratio of THF to the compound of formula (I) is 7 to 30 (or 7 to 15). This step can be carried out in the presence of a Lewis acid (e.g., lithium halide).

[0017] In one embodiment, R 1 is isopropyl, X is Cl, and R 1 Step (a) is carried out by contacting MgX with a compound of formula (I). The solvent used in this reaction can be THF, and the volume to weight ratio of THF to the compound of formula (I) is 7 to 30 (or 7 to 15). This step can be carried out in the presence of a Lewis acid (e.g., lithium halide).

[0018] In one embodiment, the base in step (b) is a metal hydroxide (eg, potassium hydroxide).

[0019] In one embodiment, the oxidizing agent in step (b) is bromine, and step (b) is carried out in the presence of an acid.

[0020] In one embodiment, R in Formula (I) and Formula (II) 2 The group is an acetyl group or a benzoyl group. 2 is a benzoyl group.

[0021] In one embodiment, the method further comprises contacting 3,6-dichloropyridazine with 2,6-dichloro-4-aminophenol to form 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline, hydrolyzing the 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline, and protecting the amine group of 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline before or after hydrolysis to form the compound of Formula (I), thereby providing the compound of Formula (I). The step of contacting 3,6-dichloropyridazine with 2,6-dichloro-4-aminophenol is carried out in a polar aprotic solvent (e.g., dimethylacetamide (DMAC)) in the presence of a base (e.g., CsCO) at a reaction temperature of 60 to 120°C (e.g., about 65°C). Further purification steps may be included. That is, before step (a), the compound of formula (I) is purified in an acidic solution at a temperature of 80 to 100°C.

[0022] In one embodiment, the method further comprises: providing an amine protecting group R 2 if present, to form 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one.

[0023] In one embodiment, a compound produced by the methods described herein, e.g., Intermediate 7, is greater than 85% pure, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%.

[0024] In one embodiment, the compound produced by the methods described herein, i.e., 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one, has less than 1.5% 6-(4-amino-2,6-dichlorophenoxy)-5-isopropylpyridazin-3(2H)-one, such as less than 1.0% 6-(4-amino-2,6-dichlorophenoxy)-5-isopropylpyridazin-3(2H)-one, or less than 0.5% 6-(4-amino-2,6-dichlorophenoxy)-5-isopropylpyridazin-3(2H)-one.

[0025] In another embodiment, the compound produced by the above method does not contain 6-(4-amino-2,6-dichlorophenoxy)-5-isopropylpyridazin-3(2H)-one.

[0026] The synthesis method of the present invention further comprises the following steps for synthesizing pyridazinone compounds as thyroid hormone analogs and their prodrugs: (d) 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with formula (IV):

[0027] [ka] [In the formula, R 3 is H or CH2R a wherein R a is a hydroxyl group, O-linked amino acid, -OP(O)(OH)2 or -OC(O)-R b and R b is a lower alkyl group, an alkoxy group, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or -(CH2) n -heteroaryl group, n is 0 or 1; R 4 is H and R 5 is CH2COOH, C(O)CO2H, or an ester or amide thereof, or R 4 and R 5are combined, and -N=C(R c )—C(O)—NH—C(O)—, wherein R c is H or a cyano group.

[0028] In one embodiment, the compound of formula (IV) is 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A"), and the process is carried out by contacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with ethyl (2-cyanoacetyl)carbamate and a metal nitrite, followed by treatment with potassium acetate in DMAC.

[0029] In one embodiment, the method further comprises forming a form of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”) (Form I), characterized by an X-ray powder diffraction pattern comprising peaks at approximately 10.5°, 18.7°, 22.9°, 23.6°, and 24.7° 2θ.

[0030] In one embodiment, the compound of formula (IV) has formula (V)

[0031] [ka] (In the formula, R 3 is CH2R a), and step (d) is carried out by contacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with ethyl (2-cyanoacetyl)carbamate followed by treatment with potassium acetate in DMAC to form 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”), and converting Compound A to the compound of formula (V) in a suitable manner, for example using one of the techniques described in U.S. Pat. No. 8,076,334.

[0032] In one embodiment, the compound of Formula (IV) prepared by the methods described herein, e.g., 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”), is greater than 85% pure, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8% pure. For example, the content of impurities (i.e., all components other than the compound of formula (IV) in the composition produced by the methods described herein, such as by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0033] In one embodiment, the compound of Formula (IV) produced by the methods described herein is Compound A Form I and has a purity of greater than 85%, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%. For example, the content of impurities (i.e., all components other than Compound A in the compositions produced by the methods described herein, such as by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0034] In one embodiment, the compound of Formula (IV) produced by the methods described herein is Compound A Form I, and Form I is greater than 85% pure, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%. For example, the content of impurities (i.e., all components other than Form I in the composition produced by the methods described herein, e.g., other forms of Compound A, by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0035] In one embodiment, a composition containing a compound of Formula (IV) (e.g., Compound A) prepared by a method described herein has less than 1.5% (e.g., less than 1.0%, e.g., less than 0.5%) of the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0036] In one embodiment, a composition containing a compound of Formula (IV) (e.g., Compound A) prepared by the methods described herein does not contain the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0037] In one embodiment, a composition containing a compound of formula (IV) (e.g., Compound A) produced by the methods described herein contains less than 1.5% (e.g., less than 0.1%) heavy metals (e.g., silver).

[0038] In one embodiment, the composition containing a compound of Formula (IV) (e.g., Compound A) produced by the methods described herein does not contain heavy metals (e.g., silver, gold, or platinum).

[0039] The synthetic method described herein offers advantages over previous methods, such as that disclosed in U.S. Pat. No. 7,452,882. For example, the overall yield of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A") is significantly higher (e.g., >40% compared to ~9% when prepared according to the method disclosed in U.S. Pat. No. 7,452,882). The regioselectivity of the synthesis is also much better. Furthermore, the novel method is easier to process, e.g., filter. Finally, the method described herein for Compound A does not involve the use of heavy metals, in contrast to the route described in U.S. Pat. No. 7,452,882, which uses silver and therefore requires resin decontamination.

[0040] In yet another embodiment, the present invention provides a compound of formula (IV) that is greater than 85% of the compound, less than 1.5% of the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (i.e.

[0041] [ka] ), and / or compositions containing less than 1.5% heavy metals.

[0042] In one embodiment, the compound of Formula (IV) (e.g., Compound A) has a purity of greater than 85%, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%. For example, the content of impurities (i.e., all components other than the compound of Formula (IV) in a composition containing the compound of Formula (IV), such as by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0043] In one embodiment, the compound of Formula (IV) is Compound A Form I and has a purity of greater than 85%, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%. For example, the content of impurities (i.e., all components other than Compound A in a composition containing Compound A, such as by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0044] In one embodiment, the compound of Formula (IV) is Compound A Form I, and Form I has a purity of greater than 85%, e.g., greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%. For example, the content of impurities (i.e., all components other than Form I in a composition containing Form I, such as other forms of Compound A, by-products, starting materials, solvent residues, heavy metals, etc.) is less than 15%, less than 14%, less than 10%, less than 8%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1.5%, less than 1%, less than 0.8%, less than 0.5%, or less than 0.2%.

[0045] In one embodiment, a compound of Formula (IV) (e.g., Compound A) has less than 1.5% (e.g., less than 1.0%, e.g., less than 0.5%) of the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0046] In one embodiment, a compound of Formula (IV) (e.g., Compound A) does not contain the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0047] In one embodiment, the compound of formula (IV) (eg, Compound A) has less than 1.5% (eg, less than 1.0%, eg, less than 0.5%) heavy metals (eg, silver, gold, or platinum).

[0048] In one embodiment, the compound of Formula (IV) (eg, Compound A) produced by the methods described herein is heavy metal (eg, silver) free.

[0049] Additionally, the present invention relates to a form (Form I) of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A") characterized by an X-ray powder diffraction ("XRPD") pattern containing peaks at approximately 2θ = 10.5°, 18.7°, 22.9°, 23.6°, and 24.7°.

[0050] In one embodiment, Form I is characterized by a powder X-ray diffraction pattern that also contains peaks at about 8.2°, 11.2°, 15.7°, 16.4°, 17.7°, 30.0°, and 32.2° 2θ.

[0051] In one embodiment, Form I is characterized by a powder X-ray diffraction pattern comprising peaks at about 8.2°, 10.5°, 18.7°, 22.9°, 23.6°, and 24.7° 2θ.

[0052] In one embodiment, Form I is characterized by a powder X-ray diffraction pattern comprising peaks at about 8.2°, 10.5°, 11.2°, 15.7°, 16.4°, 17.7°, 18.7°, 22.9°, 23.6°, and 24.7° 2θ.

[0053] In one embodiment, Form I is characterized by a powder X-ray diffraction pattern comprising peaks at about 8.2°, 10.5°, 11.2°, 15.7°, 16.4°, 17.7°, 18.7°, 22.9°, 23.6°, 24.7°, 30.0°, and 32.2° 2θ.

[0054] In another embodiment, Form I is characterized by a powder X-ray diffraction pattern substantially similar to the pattern shown in FIG.

[0055] In another aspect, the present disclosure relates to a method for producing Form I. The method includes mixing a sample containing compound A (e.g., a crude or purified preparation of compound A) with an organic solvent, such as an alcohol (e.g., ethanol), a ketone (e.g., methyl isobutyl ketone, i.e., MIBK), or an aqueous solution containing an alcohol or ketone. For example, the resulting mixture (e.g., a slurry or suspension) containing starting compound A and a solvent is heated to a first temperature and then cooled to a second temperature lower than the first temperature. The organic solvent is preferably ethanol. The starting compound A to be converted can be a solvate, such as a hydrate (e.g., a monohydrate or dihydrate) or a solvate of an organic solvent (e.g., dimethylacetamide, ethanol, or MIBK). Alternatively, the starting compound A can be a non-solvate (e.g., an anhydrate).

[0056] In one embodiment, the method is carried out by heating Compound A with an organic solvent to an elevated temperature (e.g., about 60-110°C or about 80°C) to form a slurry or suspension, followed by cooling (e.g., to a temperature of about 0-60°C, about 40-60°C, about 45-55°C, or to about room temperature) to obtain Compound A Form I. For example, the organic solvent is ethanol, and the slurry containing Compound A can be cooled to a temperature above about 40°C to obtain Form I. For example, the organic solvent is MIBK, and the slurry containing Compound A can be cooled to room temperature to obtain Form I.

[0057] In another embodiment, an ethanol suspension of Compound A is heated to an elevated temperature (e.g., about 80°C), then cooled to a temperature of about 40°C or higher (e.g., about 45-55°C), filtered (e.g., about 45-55°C), washed with warmed (e.g., 45-55°C) ethanol, and dried, e.g., at 45-55°C, to obtain Compound A Form I, which is substantially free of solvates of Compound A (e.g., ethanol solvates). For example, Compound A Form I as prepared has an ethanol solvate content of <5% (e.g., <2%, <1%, <0.5%, or <0.1%).

[0058] In one embodiment, the method further comprises filtering the mixture after cooling the mixture, which can be carried out at a temperature of about 0°C to about 60°C (e.g., about 40-60°C, about 45-55°C, or about room temperature) to obtain a filter cake.

[0059] In one embodiment, the method further comprises rinsing the filter cake after filtering the mixture, wherein the rinsing step is carried out using an organic solvent (e.g., an alcohol such as ethanol) at a temperature of about 0°C to about 60°C (e.g., about 40-60°C, about 45-55°C, or about room temperature) to obtain a rinsed filter cake.

[0060] In one embodiment, the method further comprises, after rinsing the filter cake, drying the rinsed filter cake, which is carried out at a temperature of about 0°C to about 60°C (e.g., about 40-60°C, about 45-55°C, or about room temperature) to obtain Form I of Compound A.

[0061] In one embodiment, Form I is greater than 91% pure, such as greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, or greater than 97.5%.

[0062] In one embodiment, Form I is greater than 98% pure, such as greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%.

[0063] In another aspect, the present disclosure provides compounds of the following formula:

[0064] [ka] and salts thereof.

[0065] The present disclosure also provides a method for treating thyroid hormone resistance (RTH) in a subject in need thereof, the method comprising administering to a subject having at least one TRβ mutation a therapeutically effective amount of a compound of formula (IV):

[0066] [ka] [In the formula, R 3 is H or CH2R a wherein R a is a hydroxyl group, O-linked amino acid, -OP(O)(OH)2 or -OC(O)-R b and R b is a lower alkyl group, an alkoxy group, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or -(CH2) n -heteroaryl, where n is 0 or 1; R 4 is H and R 5 is CH2COOH, C(O)CO2H, or an ester or amide thereof, or R 4 is R 5 together -N=C(R c )—C(O)—NH—C(O)—, wherein R c is H or a cyano group.

[0067] Resistance to thyroid hormone (RTH) is a syndrome characterized by reduced sensitivity of various tissues to thyroid hormone and is primarily caused by autosomal dominant mutations in THRβ. See Shi et al., Biochemistry 2005, 44, 4612-4626.

[0068] In one embodiment, the compound used in the method is 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”), for example, Form I of Compound A.

[0069] In one embodiment, the subject treated by the above method has obesity, hyperlipidemia, hypercholesterolemia, diabetes, non-alcoholic steatohepatitis, fatty liver, bone disease, thyroid axis degeneration, atherosclerosis, cardiovascular disorder, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disability, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disorder, or thyroid cancer.

[0070] In one embodiment, the THRβ mutation is selected from the group consisting of a substitution of the wild-type residue alanine (A) with threonine (T) at amino acid position 234 of SEQ ID NO: 1 (A234T); a substitution of the wild-type residue arginine (R) with glutamine (Q) at amino acid position 243 of SEQ ID NO: 1 (R243Q); a substitution of the wild-type residue arginine (R) with histidine (H) at amino acid position 316 of SEQ ID NO: 1 (R316H); and a substitution of the wild-type residue alanine (A) with threonine (T) at amino acid position 317 of SEQ ID NO: 1 (A317T). In another embodiment, the compound used in the method restores activity of the mutant THRβ.

[0071] In one embodiment, purity of a compound of Formula (IV) (e.g., Compound A) is achieved by reslurrying the crude compound in a suitable solvent as described herein. In another embodiment, the compound is not a solvate (e.g., a hydrate).

[0072] In one embodiment, the compound of Formula (IV) (e.g., Compound A) has a purity of greater than 85%, such as greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%.

[0073] In one embodiment, the compound of Formula (IV) is Compound A Form I and has a purity of greater than 85%, for example, greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%.

[0074] In one embodiment, the compound of Formula (IV) is Compound A in Form I, and Form I is greater than 85% pure, such as greater than 86%, greater than 90%, greater than 92.5%, greater than 95%, greater than 96%, greater than 97%, greater than 97.5%, greater than 98%, greater than 98.5%, greater than 99%, greater than 99.2%, greater than 99.5%, or greater than 99.8%.

[0075] In one embodiment, a compound of Formula (IV) (e.g., Compound A) has less than 1.5% (e.g., less than 1.0%, e.g., less than 0.5%) of the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0076] In one embodiment, a compound of Formula (IV) (e.g., Compound A) does not contain the corresponding β-isopropylpyridazin-3(2H)-one regioisomer (e.g., the β-isopropylpyridazin-3(2H)-one regioisomer of Compound A, 2-(3,5-dichloro-4-((4-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile).

[0077] In one embodiment, the compound of formula (IV) (eg, Compound A) has less than 1.5% (eg, less than 1.0%, eg, less than 0.5%) heavy metals (eg, silver, gold, or platinum).

[0078] In one embodiment, the subject is a mammal. In another embodiment, the subject is a human.

[0079] The present disclosure further provides a method for determining a subject's responsiveness to a compound of formula (IV) or a pharmaceutically acceptable salt thereof, said method comprising: (a) preparing a sample from a subject; (b) detecting a mutation in the thyroid hormone receptor ("TR"), and determining that the subject is responsive to the compound or a pharmaceutically acceptable salt thereof if the mutation is present.

[0080] In one embodiment, the compound of formula (IV) is 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”).

[0081] In one embodiment, TR is TRβ.

[0082] In one embodiment, the subject treated by the methods of the invention has obesity, hyperlipidemia, hypercholesterolemia, diabetes, non-alcoholic steatohepatitis, fatty liver, bone disease, thyroid axis degeneration, atherosclerosis, cardiovascular disorder, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disability, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disorder, or thyroid cancer.

[0083] In one embodiment, the method for determining responsiveness to a compound of formula (IV) can be used in conjunction with the method for treating thyroid hormone insensitivity, i.e., the subject is tested prior to treatment to determine responsiveness to the compound.

[0084] Other features and advantages of the present invention will be readily apparent from the detailed description, examples, and claims. [Brief explanation of the drawings]

[0085] [Figure 1]FIG. 1 is a powder X-ray diffraction diagram (XRPD) of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (“Compound A”) Form I. [Figure 2] FIG. 1 is a differential scanning calorimetry (DSC) diagram of Compound A Form I. [Figure 3] 3A and 3B are MacPymol modeling images showing T3 and Compound A, respectively, on THRβ. [Figure 4] MacPymol modeling image showing the overlay of T3 and Compound A in THRβ. [Figure 5] Figure 5A is a MacPymol modeling image showing the polar interactions between T3 and wild-type THRβ, where T3 interacts very specifically with Arg320, and Figure 5B is a MacPymol modeling image showing the polar interactions between Compound A and wild-type THRβ, where Compound A interacts with Arg320 and Arg316. [Figure 6] 1 is a MacPymol modeling image showing that the mutations result in many changes in the polar region of the ligand binding domain ("LBD"). [Figure 7] Figure 7A shows MacPymol modeling images of the interactions between T3 and the THRβ mutants Ala234Thr, Arg243Gln, Arg316His, and Ala317Thr. Figure 7B shows MacPymol modeling images of the interactions between compound A and the THRβ mutants Ala234Thr, Arg243Gln, Arg316His, and Ala317Thr. These images demonstrate that the negatively charged heterocycle in compound A is more susceptible to mutation than that in T3. [Figure 8]Figures 8A and 8B show MacPymol modeling images of T3 and compound A in the Arg316His mutant, respectively. In this mutant, Arg320 is rotated away from the ligand, which would weaken the T3-Arg320 interaction. However, compound A maintains a good interaction with Arg320, substituting well for the CN group and forming a cation-π interaction with the mutated His316. [Figure 9] 9A and 9B are MacPymol modeling images of Compound A in WT THRβ and mutant Arg316His, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0086] As used in the specification and claims, the singular indefinite and definite articles include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "reactant" includes not only a single reactant but also a combination or mixture of two or more different reactants, reference to a "substituent" includes two or more substituents in addition to a single substituent, and similarly for other terms.

[0087] As used herein, terms such as "for example," "for example," "such as," or "including" introduce specific examples of more general subject matter. These examples are provided merely to facilitate understanding of the disclosure and are not limiting in any way. Furthermore, as used herein, the terms "may," "optionally," "optionally," or "may optionally" mean that the circumstance described by these terms may or may not exist, and thus such a description encompasses both the presence and absence of such a circumstance. For example, the term "optionally" means that the subject may or may not exist, and thus such a description encompasses both the presence and absence of the subject.

[0088] In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.

[0089] As used herein, the abbreviations "TR" and "THR" refer to thyroid hormone receptor. TR nucleic acids and polypeptides from various species (e.g., human, rat, chicken, etc.) have been described. See, for example, R.L. Wagner et al. (2001), Molecular Endocrinology 15(3):398-410; J. Sap et al. (1986), Nature 324:635-640; C. Weinberger et al. (1986), Nature 324:641-646; and C.C. Tompson et al. (1986), Science 237:1610-1614, each of which is incorporated herein by reference in its entirety. The amino acid sequence of human TRβ is set forth, for example, in Genbank Accession No. P10828.2, which is incorporated herein by reference.

[0090] [Table 1]

[0091] Residues 234, 243, 316, and 317 of human TRβ are underlined in SEQ ID NO: 1. The portion of the human TRβ nucleotide sequence encoding the above amino acid sequence is SEQ ID NO: 2. The nucleotide sequence of human TRβ is described, for example, in Genbank Accession No. NM_000461.4, which is incorporated herein by reference.

[0092] [Table 2]

[0093] As used herein, the terms "having the formula" or "having the structure" are not limiting and are used in the same manner as the term "comprising" is generally used. The term "independently selected from" is used herein to indicate that the specified elements (e.g., R groups) can be the same or different.

[0094] The term "alkyl," as used herein, generally, but not necessarily, refers to branched or unbranched saturated hydrocarbon groups, typically having from 1 to about 24 carbon atoms (e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, etc.), and cycloalkyl groups (e.g., cyclopentyl, cyclohexyl, etc.). Generally, but not necessarily, alkyl groups herein can have from 1 to about 18 carbon atoms, and such groups can have from 1 to about 12 carbon atoms. The term "lower alkyl" refers to an alkyl group having from 1 to 6 carbon atoms, e.g., 1, 2, 3, 4, 5, or 6 carbon atoms. "Substituted alkyl" refers to an alkyl group substituted with one or more substituents, and the terms "heteroatom-containing alkyl" and "heteroalkyl" refer to an alkyl substituent having at least one carbon atom replaced with a heteroatom, as described in more detail below.

[0095] As used herein, the term "alkenyl" refers to a straight-chain, branched-chain, or cyclic hydrocarbon group containing at least one double bond and having from 2 to about 24 carbon atoms (e.g., ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl, etc.). Generally, although not necessarily, an alkenyl group herein can have from 2 to about 18 carbon atoms, e.g., from 2 to 12 carbon atoms. The term "lower alkenyl" refers to an alkenyl group having from 2 to 6 carbon atoms. The term "substituted alkenyl" refers to an alkenyl group substituted with one or more substituents, and the terms "heteroatom-containing alkenyl" and "heteroalkenyl" refer to an alkenyl group in which at least one carbon atom is replaced with a heteroatom (e.g., N, P, O, or S).

[0096] The term "alkynyl," as used herein, refers to a straight or branched chain hydrocarbon group containing at least one triple bond and having from 2 to 24 carbon atoms (e.g., ethynyl, n-propynyl, etc.). Generally, although not necessarily, alkynyl groups herein can contain from 2 to about 18 carbon atoms, and such groups can further contain from 2 to 12 carbon atoms. The term "lower alkynyl" refers to an alkynyl group containing from 2 to 6 carbon atoms. The term "substituted alkynyl" refers to an alkynyl group substituted with one or more substituents, and the terms "heteroatom-containing alkynyl" and "heteroalkynyl" refer to an alkynyl group in which at least one carbon atom has been replaced with a heteroatom.

[0097] The term "alkoxy," as used herein, refers to an alkyl group attached through a single, terminal ether linkage; i.e., an "alkoxy" group can be represented as -O-alkyl, where alkyl is defined above. A "lower alkoxy" group refers to an alkoxy group containing from 1 to 6 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, t-butyloxy, and the like. A substituent referred to herein as "C1-C6 alkoxy" or "lower alkoxy" can, for example, contain 1 to 3 carbon atoms; as another example, such a substituent can contain 1 or 2 carbon atoms (i.e., methoxy and ethoxy).

[0098] The term "alkyl acid" refers to an acid substituent present on an alkyl group, e.g., -(CH) o COOH (wherein o is an integer of 1 to 6). The alkyl group may be either a straight chain or a branched chain.

[0099] The term "aryl," as used herein, unless otherwise specified, generally, but not necessarily, refers to an aromatic substituent containing one aromatic ring or multiple aromatic rings fused, directly bonded, or indirectly bonded (such that each aromatic ring is bonded to a common group, such as a methylene or ethylene moiety) having from 5 to 30 carbon atoms. An aryl group can, for example, contain from 5 to 20 carbon atoms; as another example, an aryl group can contain from 5 to 12 carbon atoms. For example, an aryl group can contain one aromatic ring or two fused or bonded aromatic rings (e.g., phenyl, naphthyl, biphenyl, diphenyl ether, diphenylamine, benzophenone, etc.). "Substituted aryl" refers to an aryl moiety substituted with one or more substituents, and the terms "heteroatom-containing aryl" and "heteroaryl" refer to an aryl substituent in which at least one carbon atom has been replaced with a heteroatom, as described in more detail below. Unless otherwise specified, the term "aryl" encompasses rings with unsubstituted, substituted, and / or heteroatom-containing aromatic substituents.

[0100] The term "aralkyl" refers to an alkyl group having an aryl substituent, and the term "alkaryl" refers to an aryl group having an alkyl substituent, where "alkyl" and "aryl" are defined above. Generally, aralkyl and alkaryl groups herein contain from 6 to 30 carbon atoms. Aralkyl and alkaryl groups can, for example, contain from 6 to 20 carbon atoms; as another example, such groups can contain from 6 to 12 carbon atoms.

[0101] The term "amino" is used herein as -NZ 1 Z 2 In the formula, Z 1 and Z 2 is hydrogen or a non-hydrogen substituent, where the non-hydrogen substituents include, for example, alkyl, aryl, alkenyl, aralkyl, and substituted and / or heteroatom-containing versions thereof.

[0102] The terms "halo" and "halogen" are used in their conventional sense to refer to a chloro, bromo, fluoro, or iodo substituent.

[0103] The term "heteroatom-containing," as in "heteroatom-containing alkyl group" (also known as "heteroalkyl") or "heteroatom-containing aryl group" (also known as "heteroaryl"), refers to a molecule, bond, or substituent in which one or more carbon atoms have been replaced with an atom other than carbon, such as nitrogen, oxygen, sulfur, phosphorus, or silicon, typically nitrogen, oxygen, or sulfur. Similarly, the term "heteroalkyl" refers to an alkyl substituent containing a heteroatom, the terms "heterocycle" or "heterocyclic" refer to a cyclic moiety containing a heteroatom, and the terms "heteroaryl" and "heteroaromatic" refer to "aryl" and "aromatic" substituents, respectively, that contain a heteroatom, and similarly so. Examples of heteroalkyl groups include alkoxyaryl, alkylsulfanyl-substituted alkyl, N-alkylated aminoalkyl, and the like. Examples of heteroaryl substituents include pyrrolyl, pyrrolidinyl, pyridinyl, quinolinyl, indolyl, furyl, pyrimidinyl, imidazolyl, 1,2,4-triazolyl, tetrazolyl, and the like; examples of heteroatom-containing alicyclic groups are pyrrolidino, morpholino, piperazino, piperidino, tetrahydrofuranyl, and the like.

[0104] "Hydrocarbyl" refers to monovalent hydrocarbyl groups having from 1 to about 30 carbon atoms, e.g., from 1 to about 24 carbon atoms, particularly from 1 to about 18 carbon atoms, and more particularly from about 1 to 12 carbon atoms, including straight-chain, branched-chain, cyclic, saturated, and unsaturated species, such as alkyl, alkenyl, and aryl groups. "Substituted hydrocarbyl" refers to a hydrocarbyl group substituted with one or more substituents, and the term "heteroatom-containing hydrocarbyl" refers to a hydrocarbyl group in which at least one carbon atom has been replaced with a heteroatom.

[0105] The term "O-linked amino acid" refers to any amino acid, natural or synthetic, that is attached to a molecule through the oxygen of the carboxyl group of the amino acid, preferably through the carboxyl group at the carboxy terminus of the amino acid.

[0106] As used herein, the term "protecting group" refers to the temporary blocking of a particular functional moiety (e.g., O, S, or N) in a polyfunctional compound so that a reaction can be selectively carried out at another reactive site. In preferred embodiments, the protecting group must react selectively in good yield to produce a protected substrate that is stable to the anticipated reaction; the protecting group must be selectively removed in good yield with a readily available, preferably non-toxic, reagent that does not attack other functional groups; the protecting group forms an easily removable derivative (more preferably, without creating a new stereocenter); and the protecting group minimizes additional functionality to increase the number of reactive sites. As detailed herein, oxygen, sulfur, nitrogen, and carbon protecting groups can be utilized. For example, in certain embodiments, certain representative oxygen protecting groups can be utilized. These oxygen protecting groups include, but are not limited to, methyl ethers, substituted methyl ethers (e.g., MOM (methoxymethyl ether), MTM (methylthiomethyl ether), BOM (benzyloxymethyl ether), and PMBM (p-methoxybenzyloxymethyl ether)), substituted ethyl ethers, substituted benzyl ethers, silyl ethers (e.g., TMS (trimethylsilyl ether), TES (triethylsilyl ether), TIPS (triisopropylsilyl ether), TBDMS (t-butyldimethylsilyl ether), tribenzylsilyl ether, and TBDPS (t-butyldiphenylsilyl ether)), esters (e.g., formate, acetate, benzoate (Bz), trifluoroacetate, and dichloroacetate), carbonates, cyclic acetals, and ketals. Certain other exemplary embodiments utilize nitrogen protecting groups. Nitrogen protecting groups and methods of protection and deprotection are known in the art. Nitrogen protecting groups include, but are not limited to, carbamates (e.g., methyl carbamate, ethyl carbamate, substituted ethyl carbamate (e.g., Troc)), amides, cyclic imide derivatives, N-alkylamines, N-arylamines, imine derivatives, and enamine derivatives. In still other embodiments, certain representative sulfur protecting groups may be utilized.Sulfur protecting groups include, but are not limited to, aliphatic carboxylic acids (e.g., acrylic acid), maleimide, vinylsulfonyl, and optionally substituted maleic acid, in addition to the oxygen protecting groups described above. While certain other representative protecting groups are detailed herein, it should be understood that the invention is not limited to these protecting groups, and various other equivalent protecting groups can be readily recognized and utilized in the present invention using the above criteria. Additionally, various protecting groups are described in "Protective Groups in Organic Synthesis," Third Ed., Greene, T.W. and Wuts, P.G., Eds., John Wiley & Sons, New York: 1999, the entire contents of which are incorporated herein by reference.

[0107] As used in the definitions above, "substituted" in "substituted hydrocarbyl," "substituted alkyl," "substituted aryl," etc., means that at least one hydrogen atom bonded to a carbon (or other) atom in a hydrocarbyl, alkyl, aryl, or other moiety has been replaced with one or more non-hydrogen substituents. Examples of such substituents include, but are not limited to, functional groups and C-C groups in the hydrocarbyl moiety. 24 Alkyl (e.g., C1-C 18 Alkyl, more particularly C1-C 12 alkyl, more particularly C1-C6 alkyl), C2-C 24 Alkenyl (e.g., C2-C 18 Alkenyl, more particularly C2-C 12 alkenyl, more particularly C2-C6 alkenyl), C2-C 24 Alkynyl (e.g., C2-C 18 Alkynyl, more particularly C-C 12 alkynyl, more particularly C2-C6 alkynyl), C5-C 30 Aryl (e.g., C5-C 20 Aryl, more particularly C5-C 12 aryl), and C6-C 30 Aralkyl (e.g., C6-C 20 Aralkyl, more specifically C6-C 12aralkyl).

[0108] "Functional group," as mentioned in the definition above, means a non-hydrogen group containing one or more non-hydrocarbon functionalities. Examples of functional groups include, but are not limited to, halo, hydroxyl, sulfhydryl, C1-C 24 Alkoxy, C2-C 24 Alkenyloxy, C2-C 24 Alkynyloxy, C5-C 20 Aryloxy, acyl (e.g., C2-C 24 Alkylcarbonyl (-CO-alkyl) and C6-C 20 Arylcarbonyl (-CO-aryl), acyloxy (-O-acyl), C2-C 24 Alkoxycarbonyl (-(CO)-O-alkyl), C6-C 20 Aryloxycarbonyl (—(CO)—O-aryl), halocarbonyl (—CO)—X (wherein X is halo), C-C 24 Alkylcarbonate (-O-(CO)-O-alkyl), C6-C 20 Arylcarbonato (-O-(CO)-O-aryl), carboxy (-COOH), carboxylato (-COO - ), carbamoyl (-(CO)-NH2), monosubstituted C1-C 24 Alkylcarbamoyl (-(CO)-NH(C1-C 24 alkyl), disubstituted alkylcarbamoyl (-(CO)-N(C1-C 24 alkyl)2), monosubstituted arylcarbamoyl (-(CO)-NH-aryl), thiocarbamoyl (-(CS)-NH2), carbamido (-NH-(CO)-NH2), cyano (-C≡N), isocyano (-N + ≡C - ), cyanato (-OC≡N), isocyanato (-ON + ≡C - ), isothiocyanato (-SC≡N), azido (-N=N + =N - ), formyl (-(CO)-H), thioformyl (-(CS)-H), amino (-NH), mono- and di-(C1-C 24Alkyl) substituted amino, mono- and di-(C5-C 20 aryl)substituted amino, C2-C 24 Alkylamide (-NH-(CO)-alkyl), C5-C 20 Arylamide (-NH-(CO)-aryl), imino (-CR=NH (where R=hydrogen, C1-C 24 Alkyl, C5-C 20 Aryl, C6-C 20 Alkaryl, C6-C 20 aralkyl, etc.), alkylimino (-CR=N(alkyl) (where R=hydrogen, alkyl, aryl, alkaryl, etc.), arylimino (-CR=N(aryl) (where R=hydrogen, alkyl, aryl, alkaryl, etc.), nitro (-NO2), nitroso (-NO), sulfo (-SO2-OH), sulfonato (-SO2-O - ), C1-C 24 Alkyl sulfanyl (-S-alkyl, also known as "alkylthio"), aryl sulfanyl (-S-aryl, also known as "arylthio"), C1-C 24 Alkylsulfinyl (-(SO)-alkyl), C5-C 20 Arylsulfinyl (-(SO)-aryl), C1-C 24 Alkylsulfonyl (-SO2-alkyl), C5-C 20 Arylsulfonyl (-SO2-aryl), phosphono (-P(O)(OH)2), phosphonato (-P(O)(O - )2), phosphinato (-P(O)(O - )), phospho (-PO2) and phosphino (-PH2), mono- and di-(C1-C 24 Alkyl) substituted phosphino, mono- and di-(C5-C 20 aryl) substituted phosphino; and the hydrocarbyl moiety is C-C 24 Alkyl (e.g., C1-C 18 Alkyl, more particularly C1-C 12 alkyl, more particularly C1-C6 alkyl), C2-C 24 Alkenyl (e.g., C2-C 18 Alkenyl, more particularly C2-C 12alkenyl, more particularly C2-C6 alkenyl), C2-C 24 Alkynyl (e.g., C2-C 18 Alkynyl, more particularly C-C 12 alkynyl, more particularly C2-C6 alkynyl), C5-C 30 Aryl (e.g., C5-C 20 Aryl, more particularly C5-C 12 aryl), and C6-C 30 Aralkyl (e.g., C6-C 20 Aralkyl, more specifically C6-C 12 and aralkyl). Additionally, the above functional groups may be further substituted, where the particular group allows, with one or more other functional groups, such as those specifically listed above, or with one or more hydrocarbyl moieties. Similarly, the above hydrocarbyl moieties may be further substituted with one or more functional groups, such as those specifically listed above, or with other hydrocarbyl moieties.

[0109] The term "integrating a process" means shortening a multi-step process into a smaller number of steps or unit operations. Unit operations include transformations as well as processing and isolation steps. Centrifugation, filtration, distillation, decanting, settling / crystallization, and packaging are examples of unit operations. The literature provides numerous examples of integration and other process improvements (see, for example, J. Org. Chem., 2007, 72, 9757-9760).

[0110] It will be appreciated that there is some overlap among the above definitions, such that some chemical moieties may be included in more than one definition.

[0111] When a list of examples of substituted groups is preceded by the term "substituted," it is intended that the term apply to each individual instance of that group. For example, the term "substituted alkyl and aryl" should be interpreted as "substituted alkyl and substituted aryl."

[0112] The present disclosure provides methods for synthesizing compounds useful as intermediates for the synthesis of pyridazinone compounds as thyroid hormone analogs. Pyridazinone compounds as thyroid hormone analogs and their prodrugs are disclosed, for example, in U.S. Patent Nos. 7,452,882, 7,807,674, and 8,076,334.

[0113] In particular, the present invention relates to a method for preparing 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one ("Intermediate 7") or a salt thereof, said method comprising: (a)R 1 MgX or R 1 Li is reacted with the formula (I):

[0114] [ka] and contacting the compound of formula (II):

[0115] [ka] (wherein R 1 is isopropyl or isopropenyl, X is halo, and R 2 is H or an amine protecting group; (b)R 1 is isopropenyl, in the presence of a base, or 1 is isopropyl, the compound of formula (II) can be reacted with the compound of formula (III):

[0116] [ka] The method includes converting the compound of formula (I) into a compound of formula (II).

[0117] The present disclosure further relates to methods for synthesizing pyridazinone compounds and their prodrugs as thyroid hormone analogs, including those disclosed in U.S. Patent Nos. 7,452,882, 7,807,674, and 8,076,334. In particular, the present disclosure relates to compounds of formula (IV):

[0118] [ka] or a pharmaceutically acceptable salt thereof, R 3 is H or CH2R a wherein R a is a hydroxyl group, O-linked amino acid, -OP(O)(OH)2 or -OC(O)-R b and R b is a lower alkyl group, an alkoxy group, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or -(CH2) n -heteroaryl group, n is 0 or 1; R 4 is H and R 5 is CH2COOH, C(O)CO2H, or an ester or amide thereof, or R 4 and R 5 are combined, and -N=C(R c )—C(O)—NH—C(O)—, wherein R c is H or a cyano group. (a)R 1 MgX or R 1 Li is reacted with the formula (I):

[0119] [ka] and contacting the compound of formula (II):

[0120] [ka] (wherein R 1is isopropyl or isopropenyl, X is halo, and R 2 is H or an amine protecting group; (b)R 1 is isopropenyl, in the presence of a base, or 1 is isopropyl, the compound of formula (II) can be reacted with the compound of formula (III):

[0121] [ka] and converting the compound into (c) an amine protecting group R of a compound of formula (III) 2 removing, if present, 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one; and optionally (d) converting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one under appropriate conditions to a compound of formula (IV).

[0122] The present invention further provides detailed methods for synthesizing various disclosed compounds of the present invention according to the following schemes and as illustrated in the Examples.

[0123] Wherever this specification describes a composition as having, comprising, or containing particular components, this also means that the composition consists essentially of or consists of the specified components. Similarly, where methods are described as having, including, or comprising particular processing steps, this also means that the methods consist essentially of or consist of the specified steps. Furthermore, it will be understood that the order of steps or order for performing certain operations is immaterial so long as the invention remains operable. Moreover, two or more steps or operations can be performed simultaneously.

[0124] The synthetic methods of the present invention can accommodate a wide variety of functional groups and, therefore, can employ a variety of substituted starting materials. While the methods generally provide the desired final compound at or near the end of the overall process, in some cases it may be desirable to further convert the compound to its pharmaceutically acceptable salt, ester, or prodrug.

[0125] In certain embodiments, 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one ("Intermediate 7") is prepared according to Scheme 1 or 2 below.

[0126] Scheme 1: Synthesis of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (Intermediate 7) via isopropyl Grignard reagent (iPrMgX).

[0127] [ka]

[0128] Scheme 2: Synthesis of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (Intermediate 7) via isopropenyl Grignard reagent

[0129] [ka]

[0130] Stage 1: Synthesis of 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline (Compound 2) and N-(3,5-dichloro-4-((6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)benzamide or N-(3,5-dichloro-4-((6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)acetamide (Compound 4)

[0131] Compound 2 is prepared by contacting 3,6-dichloropyridazine with 2,6-dichloro-4-aminophenol in a suitable organic solvent (e.g., DMSO or DMAC) in the presence of a small amount of a suitable base such as a metal carbonate (e.g., cesium carbonate or potassium carbonate) or a metal alkoxide (e.g., potassium t-butoxide) at a suitable reaction temperature (e.g., 60-120°C) until the reaction is complete, usually for about 3-30 hours, e.g., about 3-15 hours.

[0132] After protecting 2 with a suitable amine-protecting reagent (e.g., benzoic anhydride or benzoyl chloride), the protected intermediate is treated with sodium acetate in the presence of a suitable organic solvent (e.g., acetic acid) at a suitable reaction temperature (e.g., 100-120°C) until the reaction is complete, typically for about 2-20 hours, e.g., about 5-15 hours, to produce compound 4. The crude product is purified in a suitable solvent (e.g., a mixture of water and acetic acid) at a suitable temperature (e.g., 88-100°C). Compound 2 can be subjected to hydrolysis conditions to produce acetate-protected compound 4.

[0133] Stage 2: Synthesis of N-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)benzamide or N-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)acetamide (Compound 6) and 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (Intermediate 7)

[0134] Compound 4 is contacted with isopropyl Grignard in a suitable organic solvent (e.g., tetrahydrofuran or dioxane), followed by an oxidation step to produce compound 6. The oxidation step can be carried out in a suitable organic solvent (e.g., acetic acid) in the presence of an oxidizing agent such as bromine at a suitable reaction temperature (e.g., 60 to 90°C) until the reaction is complete, usually for about 2 to 10 hours, for example, about 2 to 5 hours.

[0135] Of course, a deprotection reaction is required to complete the conversion of compound 6 to intermediate 7, in particular, the removal of the N-protecting group (i.e., acetyl or benzoyl) to provide the free amino group present in intermediate 7. Thus, in one embodiment, compound 6 (wherein R 2 is Bz.) is deprotected with a base such as a metal hydroxide (e.g., KOH or NaOH) or a metal carbonate (e.g., sodium carbonate) to provide intermediate 7. In another embodiment, compound 6 (wherein R 2 is Ac.) is deprotected with an acid such as trifluoroacetic acid to give intermediate 7.

[0136] Alternatively, compound 7 is produced by contacting compound 4 with isopropenyl Grignard in a suitable organic solvent (e.g., tetrahydrofuran or 2-methyl THF), followed by isomerization (e.g., from 5A to 6), and deprotection under treatment with a base such as a metal hydroxide (e.g., KOH). The isomerization / deprotection step is carried out at a suitable reaction temperature (e.g., 60-90°C) until the reaction is complete, typically for about 10-60 hours, e.g., about 16 hours at 90°C.

[0137] The Grignard reaction can be carried out in the presence of a Lewis acid such as LiCl or LiBr at an appropriate reaction temperature (for example, room temperature to 40°C) until the reaction is completed, usually for about 2 to 10 hours, for example, for about 2 to 5 hours.

[0138] In certain embodiments, the synthesis of compound 5 or 5A results in an improved yield of intermediate 7 compared to other methods known in the art. For example, the synthesis of 5 or 5A results in a yield of greater than 45%, greater than 50%, greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, or greater than 90%.

[0139] In certain embodiments, the Grignard reaction improves regioselectivity, so that the β-isopropyl regioisomer of compound 6, i.e.

[0140] [ka] is significantly reduced, thus increasing the purity of intermediate 7.

[0141] In one embodiment, the conversion of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (“Intermediate 7”) to Compound A is carried out according to Scheme 3 below.

[0142] [ka]

[0143] Stage 3: Synthesis of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (Intermediate 8) Intermediate 8 is prepared by contacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with ethyl (2-cyanoacetyl)carbamate and a metal nitrite (e.g., sodium nitrite) in a suitable solvent (e.g., a mixture of acetic acid and water) in the presence of an acid (e.g., HCl) at a suitable reaction temperature (e.g., below 10°C) until the reaction is complete.

[0144] Stage 4: Synthesis of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (Compound A) Compound A is prepared by contacting intermediate 8 with a base (eg, sodium acetate or potassium acetate) in a suitable solvent (eg, DMAC) at a suitable reaction temperature (eg, about 120° C.) until the reaction is complete.

[0145] In certain embodiments, the conversion of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (“Intermediate 7”) to a compound of Formula (IV) other than MGL-3916 (e.g., a prodrug thereof) is carried out under conditions such as those described in U.S. Pat. Nos. 7,452,882, 7,807,674, and 8,076,334, the contents of which are incorporated herein by reference in their entirety.

[0146] For example, the synthesis route previously disclosed in U.S. Patent No. 7,452,882 exhibited poor regioselectivity in the formation of biaryl ethers, whereas the synthesis method described herein exhibits excellent regioselectivity as a result of the introduction of an isopropenyl or isopropyl group using a Grignard reagent. Furthermore, while isolation of the biaryl ether product was virtually impossible when synthesized in kilogram quantities due to filtration times exceeding one week per batch, the method disclosed herein avoids the need to isolate the product by integrating biaryl ether formation into the benzamide protection.

[0147] The present invention provides highly purified and / or particular forms (e.g., Form I) of the compound, compositions described herein, and methods for treating or preventing obesity, hyperlipidemia, hypercholesterolemia, diabetes, non-alcoholic steatohepatitis, fatty liver, bone disease, thyroid axis degeneration, atherosclerosis, cardiovascular disorders, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disabilities, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disorders, or thyroid cancer.

[0148] It will be appreciated that the methods disclosed herein are suitable for both large-scale and small-scale production of the desired compounds. In preferred embodiments of the methods described herein, thyroid hormone analogs can be produced on a large scale, e.g., industrial production scale, rather than on an experimental / laboratory scale. For example, a batch-type process according to the disclosed method allows for the production of batches of at least 1 g, or at least 5 g, or at least 10 g, or at least 100 g, or at least 1 kg, or at least 100 kg of thyroid hormone analog. Furthermore, the method allows for the production of thyroid hormone analogs with a purity of at least 98%, or at least 98.5%, as measured by HPLC.

[0149] Pharmaceutical Composition The present invention further provides pharmaceutical compositions comprising a compound of formula IV in association with at least one pharmaceutically acceptable excipient or carrier.

[0150] A "pharmaceutical composition" is a formulation containing a compound of the present invention in a form suitable for administration to a subject. In one embodiment, the pharmaceutical composition is in bulk or unit dosage form. The unit dosage form may be in any of a variety of forms, such as a capsule, an intravenous bag, a tablet, a single-pump aerosol inhaler, or a vial. The amount of active ingredient (e.g., a formulation of the disclosed compound or its salt, hydrate, solvate, or isomer) in a unit dosage composition is an effective amount and will vary depending on the particular treatment involved. It will be apparent to those skilled in the art that routine variations in dosage may be necessary depending on the age and condition of the patient. Dosages also vary depending on the route of administration. Various routes are contemplated, including oral, pulmonary, rectal, parenteral, transdermal, subcutaneous, intravenous, intramuscular, intraperitoneal, inhalation, buccal, sublingual, intrapleural, intrathecal, and intranasal. Dosage forms for topical or transdermal administration of a compound of the present invention include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches, and inhalants. In one embodiment, the active compound is admixed under sterile conditions with a pharmaceutically acceptable carrier and any preservatives, buffers, or propellants which may be required.

[0151] As used herein, the term "pharmaceutically acceptable" means those compounds, materials, compositions, carriers, and / or dosage forms that are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without undue toxicity, irritation, allergic response, or other problem or complication, and that are commensurate with a reasonable benefit / risk ratio.

[0152] A "pharmaceutically acceptable excipient or carrier" generally refers to an excipient or carrier that is safe, non-toxic, and not biologically or otherwise harmful, and is useful in preparing pharmaceutical compositions, and includes excipients acceptable for veterinary and human medicine. As used in this specification and claims, "pharmaceutically acceptable excipient" includes both one and more than one such excipient.

[0153] Pharmaceutical compositions of the present invention are formulated to be compatible with their intended route of administration. Examples of routes of administration include parenteral, e.g., intravenous, intradermal, subcutaneous, oral (e.g., inhalation), transdermal (topical), and transmucosal administration. Solutions or suspensions used for parenteral, intradermal, or subcutaneous administration may contain the following components: a sterile diluent (e.g., water for injection, saline, fixed oils, polyethylene glycol, glycerin, propylene glycol, or other synthetic solvents); an antibacterial agent (e.g., benzyl alcohol or methylparaben); an antioxidant (e.g., ascorbic acid or sodium bisulfite); a chelating agent (e.g., ethylenediaminetetraacetic acid); a buffer (e.g., acetate, citrate, or phosphate), and an agent for adjusting tonicity (e.g., sodium chloride or glucose). pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. Parenteral formulations can be enclosed in glass or plastic ampoules, disposable syringes, or multiple-dose vials.

[0154] As used herein, the term "therapeutically effective amount" refers to an amount of an agent to treat, ameliorate, or prevent a specified disease or condition, or to exert a detectable therapeutic or inhibitory effect. Such an effect can be detected by any assay method known in the art. The precise effective amount for a given subject will vary depending on the subject's weight, size, and health; the type and severity of the condition; and the therapeutic or combination of therapeutics selected for administration. A therapeutically effective amount for a given situation can be determined by routine experimentation within the skill and judgment of a physician. In a preferred embodiment, the disease or condition being treated is a metabolic disorder.

[0155] In practicing the methods of this invention, an effective amount of any one of the compounds of this invention or a combination of any of the compounds of this invention or their pharmaceutically acceptable salts or esters is administered, either alone or in combination, by any of the conventional and acceptable methods known in the art. Thus, the compounds or compositions may be administered orally (e.g., buccal), sublingually, parenterally (e.g., intramuscularly, intravenously, or subcutaneously), rectally (e.g., suppositories or douches), transdermally (e.g., skin electroporation), or by inhalation (e.g., aerosols), in solid, liquid, or gaseous dosage forms (e.g., tablets and suspensions). Administration may be via continuous therapy in a single unit dosage form, as appropriate, or via single therapy. The therapeutic compositions may also be in the form of oil emulsions or dispersions with lipophilic salts such as pamoic acid, or in the form of biodegradable sustained-release compositions for subcutaneous or intramuscular administration.

[0156] Pharmaceutical carriers useful for preparing the compositions of the present invention can be solid, liquid, or gaseous; thus, the compositions can take the form of tablets, pills, capsules, suppositories, powders, enteric-coated or other protective preparations (e.g., bound to ion-exchange resins or packaged in lipid-protein vesicles), sustained-release preparations, solutions, suspensions, elixirs, aerosols, and the like. Carriers can be selected from various oils, including those of petroleum, animal, vegetable, or synthetic origin (e.g., peanut oil, soybean oil, mineral oil, sesame oil, etc.). Water, saline, aqueous dextrose, and glycols are preferred liquid carriers, particularly for injectable solutions (that are isotonic with blood). For example, formulations for intravenous administration include sterile aqueous solutions of the active ingredient, which can be prepared by dissolving the solid active ingredient in water to form an aqueous solution, and then sterilizing the aqueous solution. Suitable pharmaceutical excipients include starch, cellulose, talc, glucose, lactose, talc, gelatin, malt, rice, wheat flour, chalk, silica, magnesium stearate, sodium stearate, glycerol monostearate, sodium chloride, nonfat dry milk, glycerol, propylene glycol, water, ethanol, and the like. Conventional pharmaceutical additives, such as preservatives, stabilizers, wetting or emulsifying agents, salts for regulating osmotic pressure, buffers, and the like, may also be added to the compositions. Suitable pharmaceutical carriers and their formulations are described in Remington's Pharmaceutical Sciences by E.W. Martin. Such compositions, in any event, contain an effective amount of the active compound together with a suitable carrier, so as to provide a suitable dosage form for proper administration to the recipient.

[0157] The pharmaceutical formulations may further contain preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, flavoring agents, salts for regulating osmotic pressure, buffers, coating agents, or antioxidants. The formulations may also contain other therapeutically valuable substances, including active ingredients other than those of Formula I.

[0158] The compounds of the present invention are useful as pharmaceuticals for the treatment of thyroid hormone resistance (RTH) in subjects with at least one TRβ mutation, including those with obesity, hyperlipidemia, hypercholesterolemia, diabetes, nonalcoholic steatohepatitis, fatty liver, bone disease, thyroid system degeneration, atherosclerosis, cardiovascular disorders, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disabilities, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disorders, or thyroid cancer.

[0159] The therapeutically effective amount or dose of the compounds of the present invention can vary widely and can be determined by methods known in the art. For example, drugs can be administered based on body weight. Such doses are adjusted to suit the individual requirements of each particular case, including the specific compound administered, the route of administration, the condition being treated, and the patient being treated. In another embodiment, drugs can be administered as a fixed dose, e.g., not adjusted based on body weight. Generally, for oral or parenteral administration to adults, a daily dose of about 0.5 mg to about 1000 mg is considered appropriate, although this upper limit may be exceeded if necessary. Doses of about 5 mg to about 400 mg per day are preferred. A preferred dose may be about 20 mg to about 100 mg per day. The daily dose can be administered in a single dose or in divided doses, or, for parenteral administration, by continuous infusion.

[0160] An effective amount of a drug is that amount that produces an objectively noticeable improvement as determined by a physician or other qualified observer. As used herein, the term "dosage effective" refers to that amount of an active compound to produce a desired biological effect in a subject or cell.

[0161] The pharmaceutical compositions can be included in a container, pack, or dispenser together with instructions for administration.

[0162] The compounds of the present invention can also form salts, and all of these forms are included within the scope of the present invention.

[0163] As used herein, the term "pharmaceutically acceptable salts" refers to derivatives of the compounds of the present invention wherein the parent compound is transformed by forming acid or base salts thereof. Examples of pharmaceutically acceptable salts include, but are not limited to, inorganic or organic acid salts of basic residues such as amines, alkalis, or organic salts of acidic residues such as carboxylic acids. Pharmaceutically acceptable salts include the conventional non-toxic salts or quaternary ammonium salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. For example, such conventional non-toxic salts include, but are not limited to, 2-acetoxybenzoic acid, 2-hydroxyethanesulfonic acid, acetic acid, ascorbic acid, benzenesulfonic acid, benzoic acid, bicarbonate, carbonic acid, citric acid, edetic acid, ethanedisulfonic acid, 1,2-ethanesulfonic acid, fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, glycolic acid, glycolylarsanilic acid, hexylresorcylic acid, hydrabamic acid, hydrobromic acid, hydrochloric acid, hydroiodic acid, hydroxymaleic acid, hydroxynaphthoic acid, isethionate, Acids include those derived from inorganic and organic acids selected from lactic acid, lactobionic acid, laurylsulfonic acid, maleic acid, malic acid, mandelic acid, methanesulfonic acid, napsylic acid, nitric acid, oxalic acid, pamoic acid, pantothenic acid, phenylacetic acid, phosphoric acid, polygalacturonic acid, propionic acid, salicylic acid, stearic acid, basic acetic acid, succinic acid, sulfamic acid, sulfanilic acid, sulfuric acid, tannic acid, tartaric acid, toluenesulfonic acid, and common amino acids (e.g., glycine, alanine, phenylalanine, arginine, etc.).

[0164] Other examples of pharmaceutically acceptable salts include those derived from hexanoic acid, cyclopentanepropionic acid, pyruvic acid, malonic acid, 3-(4-hydroxybenzoyl)benzoic acid, cinnamic acid, 4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-toluenesulfonic acid, camphorsulfonic acid, 4-methylbicyclo-[2.2.2]-oct-2-ene-1-carboxylic acid, 3-phenylpropionic acid, trimethylacetic acid, tert-butylacetic acid, muconic acid, and the like. The present invention also includes salts formed when an acidic proton present in the parent compound is replaced by a metal ion (e.g., an alkali metal ion, alkaline earth ion, or aluminum ion) or when coordinated with an organic base such as ethanolamine, diethanolamine, triethanolamine, tromethamine, N-methylglucamine, diethylamine, diethylaminoethanol, ethylenediamine, imidazole, lysine, arginine, morpholine, 2-hydroxyethylmorpholine, dibenzylethylenediamine, trimethylamine, piperidine, pyrrolidine, benzylamine, tetramethylammonium hydroxide, and the like.

[0165] It will be understood that any reference to a pharmaceutically acceptable salt also includes the solvent addition forms (solvates) or crystal forms (polymorphs), as defined herein, of the same salt.

[0166] The compounds of the present invention can also be prepared as esters (e.g., pharmaceutically acceptable esters). For example, a carboxylic acid functional group in the compound can be converted to its corresponding ester (e.g., a methyl, ethyl, or other ester). Also, an alcohol group in the compound can be converted to its corresponding ester (e.g., an acetate, propionate, or other ester).

[0167] The compounds of the present invention can also be prepared as prodrugs (e.g., pharmaceutically acceptable prodrugs). The terms "pro-drug" and "prodrug" are used interchangeably herein and refer to any compound that releases an active parent drug in vivo. Because prodrugs are known to enhance many desirable qualities of pharmaceuticals (e.g., solubility, bioavailability, manufacturability, etc.), the compounds of the present invention can be delivered in prodrug form. Accordingly, the present invention also encompasses prodrugs of the compounds of the present invention, methods for delivering such prodrugs, and compositions containing such prodrugs. The term "prodrug" also encompasses any covalently bonded carrier that releases the active parent drug of the present invention in vivo when such prodrug is administered to a subject. Prodrugs of the present invention are prepared by modifying functional groups present in the compound so that they are cleaved, by routine manipulation or in vivo, to yield the parent compound. Prodrugs include compounds of the present invention bonded to any group that can be cleaved in vivo to form a free hydroxyl group, a free amino group, a free sulfhydryl group, a free carboxy group, or a free carbonyl group, respectively.

[0168] Examples of prodrugs include, but are not limited to, esters (e.g., acetate, dialkylaminoacetate, formate, phosphate, sulfate, and benzoate derivatives) and carbamates (e.g., N,N-dimethylaminocarbonyl) of hydroxy functional groups in the compounds of the present invention, esters (e.g., ethyl ester, morpholinoethanol ester) of carboxyl functional groups, N-acyl derivatives (e.g., N-acetyl) of amino functional groups, N-Mannich bases, Schiff bases, and enaminones, oximes, acetals, ketals, and enol esters of ketone and aldehyde functional groups, etc. See Bundegaard, H., Design of Prodrugs, pp. 1-92, Elesevier, New York-Oxford (1985).

[0169] The compounds or pharmaceutically acceptable salts, esters, or prodrugs thereof may be administered orally, intranasally, transdermally, pulmonary, by inhalation, buccal, sublingually, intraperitoneally, subcutaneously, intramuscularly, intravenously, rectally, intrapleurally, intrathecally, and parenterally. In one embodiment, the compounds are administered orally. The advantages of certain administration routes will be apparent to those skilled in the art.

[0170] The dosage regimen utilizing the compounds is selected according to various factors, such as the type, species, age, weight, sex, and condition of the patient; the severity of the condition being treated; the route of administration; the renal and hepatic function of the patient; and the particular compound or salt thereof being utilized. A physician or veterinarian of ordinary skill can readily determine and prescribe the effective amount of the drug required to prevent, counter, or arrest the progress of the condition.

[0171] Techniques for formulation and administration of the compounds disclosed herein may be consulted in Remington: The Science and Practice of Pharmacy, 19th ed., Mack Publishing Co., Easton, PA (1995). In one embodiment, the compounds described herein and their pharmaceutically acceptable salts are used in pharmaceutical preparations with a pharmaceutically acceptable carrier or diluent. Suitable pharmaceutically acceptable carriers include inert solid fillers or diluents and sterile aqueous or organic solutions. The compounds are present in such pharmaceutical compositions in an amount sufficient to provide the desired dosage within the range described herein.

[0172] The present invention relates to a method of treating or alleviating symptoms of thyroid hormone insensitivity in a subject by administering a therapeutically effective amount of a compound of formula (IV), e.g., Compound A (e.g., Form I thereof), to a subject expressing a mutant TRβ comprising a mutation in the ligand-binding domain.

[0173] The present disclosure further provides a method for determining the responsiveness of a subject with thyroid hormone insensitivity (RTH) to a compound of Formula (IV) disclosed herein by providing a sample from the subject; detecting at least one TRβ mutation (e.g., a genetic mutation or mutation in the ligand-binding domain of a TRβ polypeptide, e.g., the polypeptide set forth in SEQ ID NO: 1), and determining that the subject is responsive to a compound of Formula (IV), e.g., Compound A (e.g., Form I thereof), if the mutation is present. The method can further include treating the subject with the mutation by administering a therapeutically effective amount of a compound of Formula (IV), e.g., Compound A (e.g., Form I thereof).

[0174] In one embodiment, the subject currently or future responsive to a compound of Formula (IV), such as Compound A, has obesity, hyperlipidemia, hypercholesterolemia, diabetes, non-alcoholic steatohepatitis, fatty liver, bone disease, thyroid system degeneration, atherosclerosis, cardiovascular disorder, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disability, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disease, or thyroid cancer.

[0175] The present disclosure further provides a method comprising determining the presence or absence of a TRβ gene mutation in a sample from a subject; and selecting a treatment comprising administering a therapeutically effective amount of a compound of formula (IV), e.g., Compound A (e.g., Form I thereof), based on the presence or absence of the TRβ gene mutation.

[0176] The present disclosure further provides a method comprising: amplifying nucleic acid in a sample from a subject with primers complementary to a mutant TRβ nucleic acid sequence comprising a TRβ gene mutation in the nucleic acid sequence set forth in SEQ ID NO: 2; determining the presence or absence of the amplified nucleic acid; and selecting a treatment comprising administering a therapeutically effective amount of a compound of formula (IV) based on the presence or absence of the amplified nucleic acid, or treating the subject by administering a therapeutically effective amount of a compound of formula (IV) based on the presence or absence of the amplified nucleic acid.

[0177] The mutant TRβ described herein is a mutant TRβ polypeptide or a nucleic acid sequence encoding the mutant TRβ polypeptide.

[0178] In one embodiment, the mutant TRβ comprises one or more mutations at amino acid positions 234, 243, 316, and 317 of SEQ ID NO: 1. More preferably, the mutations are selected from the group consisting of a substitution of the wild-type residue alanine (A) at amino acid position 234 of SEQ ID NO: 1 with threonine (T) (A234T); a substitution of the wild-type residue arginine (R) at amino acid position 243 of SEQ ID NO: 1 with glutamine (Q) (R243Q); a substitution of the wild-type residue arginine (R) at amino acid position 316 of SEQ ID NO: 1 with histidine (H) (R316H); and a substitution of the wild-type residue alanine (A) at amino acid position 317 of SEQ ID NO: 1 with threonine (T) (A317T).

[0179] In one embodiment, a mutant TRβ comprises a nucleic acid sequence encoding a mutant TRβ polypeptide having one or more mutations at amino acid positions 234, 243, 316, and 317 of SEQ ID NO: 1. Nucleic acid sequences encoding mutant TRβ polypeptides or peptide fragments characteristic of mutant TRβ polypeptides can be detected using any suitable method. For example, nucleic acid sequences encoding mutant TRβ polypeptides can be detected using full-length genome resequencing or targeted region resequencing (the latter also referred to as targeted resequencing) using an appropriately selected DNA source and polymerase chain reaction (PCR) primers according to methods well known in the art. See, e.g., Bentley (2006) Curr Opin Genet Dev. 16:545-52 and Li et al. (2009) Genome Res 19:1124-32. The method typically involves genomic DNA purification, PCR amplification to amplify the region of interest, cycle sequencing, sequencing reaction cleanup, capillary electrophoresis, and data analysis. High-quality PCR primers are designed to address the region of interest using an in silico primer design tool. Cycle sequencing is a simple method for linearly amplifying extension products using sequential rounds of denaturation, annealing, and extension in a thermal cycler. Typically, fluorescent tags identifying the terminal nucleotide base as G, A, T, or C are added to the end of the product. Unincorporated dye terminators and salts may compete for capillary electrophoresis injection and are removed by washing. During capillary electrophoresis, the products of the cycle sequencing reaction migrate through a capillary filled with polymer. Negatively charged DNA fragments are separated by size as they migrate through the capillary toward the positive electrode. After electrophoresis, a raw data sample file is generated using data acquisition software. Further data analysis is performed using downstream software applications to translate the acquired color data images into corresponding nucleotide bases.Alternatively or additionally, the method can include the use of microarray-based genomic DNA detection and / or sequencing of target regions. Kits, reagents, and methods for selecting appropriate PCR primers and performing resequencing are commercially available, for example, from Applied Biosystems, Agilent, and NimbleGen (Roche Diagnostics GmbH). For use in the present invention, PCR primers can be selected to amplify at least a portion of a nucleic acid sequence encoding a mutant TRβ polypeptide having one or more mutations at amino acid positions 234, 243, 316, and 317 of SEQ ID NO:1.

[0180] Alternatively or additionally, Southern blotting may be used to detect nucleic acid sequences encoding mutant TRβ polypeptides according to methods well known in the art.

[0181] In certain embodiments, the methods of the invention include performing an assay to detect a mutant form of TRβ in a sample from a subject. As used herein, a "sample from a subject" refers to any suitable sample containing cells or cellular components obtained or derived from a subject. In one embodiment, the sample is a blood sample. In one embodiment, the sample is, for example, a biopsy sample obtained from the thyroid gland.

[0182] The present disclosure further provides a ligand-mutant TRβ complex comprising a mutant TRβ polypeptide and a compound of Formula (IV). For example, the mutant TRβ polypeptide forming the complex comprises one or more mutations at amino acid positions 234, 243, 316, and 317 of SEQ ID NO: 1. For example, the compound forming the complex is Compound A.

[0183] The present disclosure further provides a primer-nucleic acid complex comprising a mutant TRβ nucleic acid sequence and a PCR primer complementary to the mutant TRβ nucleic acid sequence, wherein the mutant nucleic acid sequence comprises an EZH2 gene mutation in the nucleic acid sequence set forth in SEQ ID NO:2.

[0184] All patents, patent applications, and publications cited herein are incorporated herein by reference in their entirety. However, when a patent, patent application, or publication containing express definitions is incorporated herein by reference, those express definitions should be understood to apply to the incorporated patent, patent application, or publication in which those definitions are contained, and not to other portions of the specification of this application, particularly the claims of this application.

[0185] While the present invention has been described with reference to certain preferred embodiments thereof, it should be understood that the above description and the following examples are illustrative of the present invention and are not intended to limit its scope. It will be understood by those skilled in the art that various modifications and equivalent substitutions are possible without departing from the scope of the present invention, and that other aspects, advantages, and modifications will occur to those skilled in the art to which the present invention pertains.

[0186] All percentages and ratios used herein are by weight unless otherwise specified. Other features and advantages of the present invention will be apparent from the various examples that follow. The following examples illustrate various elements and techniques useful in practicing the present invention. The following examples do not limit the claimed invention. Based on this disclosure, one of ordinary skill in the art will be able to recognize and utilize other elements and techniques useful in practicing the present invention. [Example]

[0187] Unless otherwise specified, the analytical instruments and parameters used for the compounds described in the examples below are as follows:

[0188] XRPD data were acquired on a powder X-ray diffractometer (CubiX-Pro XRD) using CuKα radiation (45 kV, 40 mA) from 2θ = 3 to 45° with a scan rate of 0.12° / min and a step size of 0.020°.

[0189] The sample was placed in a Si zero-reset ultramicro sample holder. Analysis was performed using a 10 mm beam width, with the following hardware / software parameters: X-ray tube: CuKα, 45kV, 40mA Detector: X'Celerator ASS main slit: 1° fixed Divergence slit (Prog): Automatic - 5mm irradiation length Soller slit: 0.02 radians Scattering slit (PASS): Automatic - 5mm observation length Scan range: 3.0~45.0° Scan Mode: Continuous Step size: 0.02° Time per step: 10 seconds Operating length: 2.54°.

[0190] After analysis, the data was converted from adjustable to fixed slit using X'Pert HighScore Plus software with the following parameters: Fixed divergence slit size: 1.00°, 1.59mm Intersection: 44.3 °ω.

[0191] In the following examples, unless otherwise specified, compound 4 is a compound protected with a benzoyl group.

[0192] Example 1: N-(3,5-dichloro-4-((6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)benzamide (R 2 Preparation of compound 4) where is benzoyl A 1 L three-neck round-bottom flask equipped with an overhead stirrer, thermocouple, reflux condenser, and N2 inlet / outlet was charged with 3,6-dichloropyridazine (100 g, 0.672 mol, 1 wt), 4-amino-2,6-dichlorophenol (122 g, 0.686 mol, 1.02 equiv), and DMAC (500 mL, 5 vol). Cesium carbonate (251 g, 0.771 mol, 1.15 equiv) was added to the resulting solution, and the suspension was heated to 110 °C. After 3 h at this temperature, the batch temperature was reduced to 70 °C and stirred at this temperature for 16 h. 1H NMR analysis (DMSO) indicated that nearly all of the dichloropyridazine had been consumed, and the reaction was deemed complete. The batch was cooled to room temperature and transferred to a 3 L round-bottom flask using EtOAc (2 L, 20 vol). Silica gel (100 g, 1 wt) was added, and the suspension was stirred for 30 min and filtered. The reaction vessel and cake were rinsed with EtOAc (500 mL, 5 vol) until the filtrate eluted colorless. The resulting filtrate was treated with 10% aqueous NaCl (2 L, 20 vol), and the biphasic mixture was stirred for 30 min. The lower aqueous layer was discarded. The upper organic layer was concentrated to dryness under reduced pressure. EtOAc (100 mL, 1 vol) was added to the residue, and the mixture was concentrated to dryness under reduced pressure to give the crude product, compound 2 (251 g, 128% yield), as an oil. HPLC analysis indicated a purity of 93.4%. 1 1 H NMR analysis (DMSO) was consistent with the assigned structure and showed the presence of ≈25% DMAC and 2% EtOAc.

[0193] Other synthesis conditions for Compound 2 are listed in Tables 1 to 3 below.

[0194] [Table 3]

[0195] [Table 4]

[0196] [Table 5]

[0197] The crude product 2 was dissolved in acetic acid (1.48 L, 7.5 vol) and benzoic anhydride (168 g, 0.741 mol, 1.1 eq) was added. The resulting mixture was heated to 100 °C, and after 35 min at this temperature, the amount of 2 was 0.8%. Sodium acetate (110 g, 2 eq) was added and the temperature was increased to 110 °C. After 14.5 h at this temperature, HPLC analysis of the reaction mixture indicated no intermediate remained, and the reaction was deemed complete. The batch was cooled to 75 °C, and water (1.5 L, 7.7 vol) was added over 1 h, maintaining the batch temperature at 72–75 °C. The batch was cooled to 21 °C and filtered through Sharkskin filter paper. The reaction vessel and cake were successively washed with water (1 L, 5 vol). The collected solid was dried in a vacuum oven at 50°C for 16 hours, after which the yield of crude product 4 was 195g (77%). HPLC analysis (Method B, 220nm) showed a purity of 91.6%.

[0198] HPLC method B: Column: Waters Sunfire C18, 3.5 μM, 4.6 × 150 mm Flow rate: 1.0mL / min. Mobile phase A: 0.05% TFA aqueous solution Mobile phase B: 0.05% TFA aqueous solution Diluent: 50:50 MeCN / H2O

[0199] [Table 6]

[0200] 1 H NMR analysis (DMSO) was consistent with the assigned structure and showed 1% acetic acid content. Benzoyl chloride was also used for protection instead of benzoic anhydride. When benzoyl chloride was used, a base such as cesium carbonate or potassium carbonate was used and the reaction was carried out at room temperature.

[0201] Other synthesis conditions for Compound 4 are listed in Tables 4 and 5 below.

[0202] [Table 7]

[0203] [Table 8]

[0204] Purification of Compound 4: A 5 L, three-necked round-bottom flask equipped with an overhead stirrer, thermocouple, reflux condenser, and N2 inlet / outlet was charged with crude product 4 (100 g, 1 wt.) and acetic acid (2 L, 20 vol.). The slurry was stirred and heated to 95 °C, resulting in dissolution. Water (2 L, 20 vol.) was added over 2.75 h, maintaining the batch temperature at ≈95 °C, resulting in precipitation. The resulting slurry was heated to 95 °C for an additional 30 min, after which heating was discontinued. After the batch reached ambient temperature, it was conveniently stirred at this temperature overnight and filtered through Sharkskin filter paper. The reaction vessel and cake were rinsed successively with water (1 L, 10 vol.). The collected white solid was dried in a vacuum oven at 40 °C to a constant weight of 91 g (91%). HPLC analysis of the dried solid indicated a purity of 98.0%. 1 H NMR analysis (DMSO) was consistent with the assigned structure and the acetic acid content was 0.3%. Table 6 below summarizes other purification conditions for compound 4.

[0205] [Table 9]

[0206] Example 2: Preparation of 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one (Intermediate 7) A 4 L four-neck round-bottom flask equipped with an overhead stirrer, thermocouple, N2 inlet / outlet, and reflux condenser was charged with 4 (95 g, 0.253 mol, 1 wt), THF (665 mL, 7 vol), and LiCl (32.3 g, 0.759 mol, 3 equiv). The resulting suspension was heated to 35 °C, and isopropenyl magnesium bromide solution (0.5 M in THF, 1.72 L, 0.859 mol, 3.4 equiv) was added over 80 min while maintaining the batch temperature between 35 and 45 °C. The resulting slurry was heated to 40 °C for 3 h, after which HPLC analysis indicated 87% conversion. Isopropenyl magnesium bromide solution (0.5 M in THF, 51 mL, 0.026 mol, 0.1 equiv) was added, and the slurry was stirred at 40–43 °C for an additional 90 min. HPLC analysis indicated 92.9% conversion, and the reaction was deemed complete. Heating was discontinued, the reaction mixture was cooled to 14°C, and 3N aqueous HCl (380 mL, 4 vol) was added slowly over 15 minutes while maintaining the batch temperature below 26°C, until all solids dissolved. The lower aqueous layer was discarded and extracted with THF (350 mL, 3.7 vol). After discarding the lower aqueous layer, the organic layers were combined and concentrated under reduced pressure to approximately 5 volumes relative to 4. 10% (w / w) aqueous KOH (532 mL, 5.6 vol) was added to the resulting solution, and the mixture was heated to 85°C while distilling off the THF using a short-path distillation apparatus. The batch was maintained at 85°C for 11 hours, at which point heating was discontinued. The batch was conveniently allowed to cool to ambient temperature overnight. HPLC analysis of the resulting slurry (Method A, below) indicated 99% conversion to intermediate 7, and the reaction was deemed complete.

[0207] HPLC Method A Column: Waters Sunfire C18, 3.5 μM, 4.6 × 150 mm Flow rate: 1.0mL / min. Mobile phase A: 0.05% TFA aqueous solution Mobile phase B: 0.05% TFA aqueous solution Diluent: 50:50 MeCN / H2O.

[0208] [Table 10]

[0209] The batch temperature was adjusted to 48°C, and 3N aqueous HCl (152 mL, 1.6 volumes) was added over 35 minutes while maintaining the batch temperature at 46-48°C to adjust the pH to 7.5-8.0. Heating was stopped, and the slurry was cooled to 30°C. 1 H NMR analysis (DMSO) indicated that the molar ratio of intermediate 7 to THF was 1.0:0.22 (Appendix 14). The batch was filtered through Sharkskin filter paper at 30 °C, and the reaction vessel and cake were washed with water (475 mL, 5 volumes). The beige solid intermediate 7 was dried in a vacuum oven at 40 °C to a constant weight of 81.6 g (102% yield). Karl Fischer analysis indicated a water content of 0.8%. 1 H NMR (DMSO) was consistent with the assigned structure, with a THF content of 0.4%. HPLC analysis indicated a purity of 92.6%. Tables 7-10 below outline the reaction parameters for preparing Intermediate 7.

[0210] [Table 11] TIFF2025179154000032.tif102161

[0211] [Table 12] TIFF2025179154000034.tif98161

[0212] [Table 13]

[0213] [Table 14]

[0214] Example 3: Preparation of (Z)-ethyl (2-cyano-2-(2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)hydrazono)acetyl)carbamate (Intermediate 8) A 2 L, three-necked round-bottom flask equipped with an overhead stirrer, thermocouple, and N2 inlet / outlet was charged with intermediate 7 (75.0 g, 0.239 mol, 1 wt), acetic acid (600 mL, 8 vol), water (150 mL, 2 vol), and concentrated HCl (71.3 mL, 0.95 vol). The resulting thin slurry was cooled to 6 °C, and a solution of NaNO2 (16.8 g, 0.243 mol, 1.02 equiv) in water (37.5 mL, 0.5 vol) was added over 10 min, maintaining the batch temperature below 10 °C. After stirring for an additional 10 min at 5–10 °C, HPLC analysis indicated complete conversion of intermediate 7 to the diazonium intermediate. A solution of NaOAc (54.5 g, 0.664 mol, 2.78 equiv.) in water (225 mL, 3 vol.) was added over 6 min, maintaining the batch temperature below 10 °C. N-Cyanoacetylurethane (37.9 g, 0.243 mol, 1.02 equiv.) was immediately added, cooling was removed, and the batch was allowed to warm to 8 °C over 35 min. HPLC analysis indicated complete consumption of the diazonium intermediate, and the reaction was deemed complete. The batch was allowed to warm to 21 °C and filtered through Sharkskin filter paper. The reaction vessel and cake were washed twice with water (375 mL, 5 vol.). The orange solid was collected and dried in a vacuum oven at 35 °C for 64 h to give crude Intermediate 8 (104.8 g, 91%).

[0215] A 1 L, three-necked round-bottom flask equipped with an overhead stirrer, thermocouple, and N2 inlet / outlet was charged with crude Intermediate 8 (104.4 g, 1 wt) and acetic acid (522 mL, 5 vol). The resulting slurry was heated to 50 °C and maintained at this temperature for 1.5 hours. The batch was allowed to cool to 25 °C over 2 hours and then filtered through Sharkskin filter paper. The reaction vessel and cake were washed sequentially with water (522 mL, 5 vol), and the cake was conditioned under vacuum for 1.75 hours. The resulting bright orange solid was dried to constant weight in a vacuum oven at 40 °C to give 89.9 g of the desired product (78% yield from Intermediate 7). 1 1 H NMR (DMSO) was consistent with the assigned structure.

[0216] Example 4: Preparation of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (Compound A) A 2 L, three-necked round-bottom flask equipped with an overhead stirrer, thermocouple, N2 inlet / outlet, and reflux condenser was charged with Intermediate 8 (89.3 g, 0.185 mol, 1 wt), DMAC (446 mL, 5 vol), and KOAc (20.0 g, 0.204 mol, 1.1 eq). The mixture was heated to 120 °C and maintained at this temperature for 2 h. HPLC analysis indicated complete conversion to compound A. The batch temperature was adjusted to 18 °C over 1 h, and acetic acid (22.3 mL, 0.25 vol) was added. The batch temperature was adjusted to 8 °C, and water (714 mL, 8 vol) was added over 1 h, forming an orange slurry. The batch was filtered through Sharkskin filter paper, and the cake was conveniently conditioned under N2 without vacuum overnight. A premixed solution of 1:1 acetone / water (445 mL, 5 vol) was added to the flask and added to the cake as a rinse under vacuum. The cake was conditioned under vacuum for 2 hours and then transferred to a clean 1 L three-neck round-bottom flask equipped with an overhead stirrer, thermocouple, and N2 inlet / outlet. Ethanol (357 mL, 4 vol) and acetone (357 mL, 4 vol) were added, and the resulting slurry was heated to 60 °C to induce dissolution. Water (890 mL, 10 vol) was added over 90 min while maintaining the batch temperature at 55–60 °C. The resulting slurry was cooled to 25 °C and filtered through Sharkskin filter paper. The reaction vessel and cake were washed sequentially with 1:1 EtOH / water solution (446 mL, 5 vol). The cake was expediently conditioned under N2 without vacuum overnight. Cracks in the cake were smoothed and vacuum applied. The cake was washed with water (179 mL, 2 volumes) and dried in a vacuum oven at 45°C to a constant weight of 70.5 g (87%, crude Compound A), with a purity of 94.8% by HPLC analysis.

[0217] Crude compound A (70.0 g) and MIBK (350 mL, 5 vol) were charged to a 500 mL three-neck round-bottom flask equipped with an overhead stirrer, thermocouple, N2 inlet / outlet, and reflux condenser. The resulting orange slurry was heated to 50 °C and maintained at this temperature for 2 hours. The batch was allowed to cool to 23 °C and filtered through Sharkskin filter paper. The reactor and cake were washed twice with MIBK (35 mL, 0.5 vol). The solid was collected and dried in a vacuum oven at 45 °C to a constant weight of 58.5 g (84%). The solid was added to a 500 mL three-neck round-bottom flask equipped with an overhead stirrer, thermocouple, N2 inlet / outlet, and reflux condenser. Ethanol (290 mL, 5 vol) was added, and the slurry was heated to reflux. After 3.5 hours at reflux, XRPD indicated the solid was consistent with Form I, so heating was discontinued. Upon reaching 25°C, the batch was filtered through filter paper, and the reaction vessel and cake were washed sequentially with EtOH (174 mL, 3 volumes). Compound A, a tan solid, was dried in a vacuum oven at 40°C to a constant weight of 50.4 g (87%, 64% yield from Intermediate 8). HPLC analysis indicated a purity of 99.1%. 1 1 H NMR (DMSO) was consistent with the assigned structure.

[0218] Example 5: Large-scale preparation of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (Compound A) A large-scale batch of Compound A was synthesized according to the following scheme: The conditions in the scheme below are similar to those described in Examples 1 to 4 above.

[0219] [ka]

[0220] Synthesis of 4: A 50 L jacketed glass vessel (under N2) was charged with 3,6-dichloropyridazine (2.00 kg), 4-amino-2,6-dichlorophenol (2.44 kg), and N,N-dimethylacetamide (10.0 L). The batch was subjected to vacuum (26 in Hg) / nitrogen (1 PSIG) three times. Cesium carbonate (5.03 kg) was added and the batch temperature was adjusted from 22.3°C to 65.0°C over 3.5 hours. The batch was maintained at 65.0°C for 20 hours. At this point, 1 H NMR analysis indicated 3.34% 3,6-dichloropyridazine relative to 2. The batch temperature was adjusted to 21.5°C, and ethyl acetate (4.00 L) was added to the batch. The batch was stirred for 10 minutes and then filtered through an 18" Nutsche filter fitted with a polypropylene filter cloth. Filtration took 15 minutes. Ethyl acetate (5.34 L) was added to the vessel and transferred to the filter as a rinse. The batch was then manually resuspended in the filter, and vacuum was again applied. This process was repeated two more times, and the filter cake was conditioned for 10 minutes. The filtrate was added to a 100 L vessel containing a previously prepared 15% aqueous sodium chloride solution (16.0 L). The batch was stirred for 5 minutes and then allowed to separate for 35 minutes. Since no interface was observed, the calculated lower aqueous phase of 23 L was discarded. 16.0 L of 15% aqueous sodium chloride solution was added to the batch. The batch was added. The batch was stirred for 6 minutes and then allowed to separate for 7 minutes. An interface was observed at ~19 L and the lower aqueous phase was discarded. 17.0 L of 15% aqueous sodium chloride solution was added to the batch. The batch was stirred for 7 minutes and then allowed to separate for 11 minutes. The lower aqueous phase was discarded. The vessel was set up for vacuum distillation and the batch was concentrated from 17.0 L to 8.0 L over 2 hours and 20 minutes, maintaining the batch temperature near 21°C. Benzoic anhydride (3.19 kg) and acetic acid (18.0 L) were added to the vessel. The vessel was set up for vacuum distillation and the batch was concentrated from 28.0 L to 12.0 L over 2 days (held at 20°C overnight) maintaining the batch temperature between 20-55°C. At this point, 1 H NMR analysis indicated that the molar ratio of acetic acid to ethyl acetate was 1.0:0.015. Acetic acid (4.0 L) was added to the batch and the batch was distilled to 12 L. 1H NMR analysis indicated a molar ratio of acetic acid to ethyl acetate of 1.0:0.0036. Acetic acid (20.0 L) was added to the batch and the batch temperature was adjusted to 70.0°C. The batch was sampled and analyzed by HPLC, which showed 0.16% 2. Sodium acetate (2.20 kg) was added to the batch and the batch temperature was adjusted from 72.4°C to 110.0°C. After 18.5 hours, no intermediate B was detected by HPLC analysis. The batch temperature was adjusted from 111.3°C to 74.7°C, and deionized water (30.0 L) was added to the batch over 2 hours. After adjusting the batch temperature to 20.5°C, the mixture was filtered through a 24" Haselloy filter fitted with a polypropylene filter cloth. The mixture was filtered using a Nutsche filter. A previously prepared solution of 10.0 L of acetic acid in deionized water was added to the vessel and stirred for 5 minutes. After the wash was transferred to the filter, the batch was manually resuspended on the filter and vacuum was applied again. Deionized water (10.0 L) was added to the vessel and then transferred to the filter. The batch was manually resuspended on the filter and vacuum was applied again. Deionized water (10.0 L) was added directly to the filter, after which the batch was manually resuspended on the filter and vacuum was applied again. The filter cake was conditioned for 18 hours to yield 14.4 kg of 4. HPLC analysis showed a purity of 93.7%. This wet cake was subjected to purification. A 100 L jacketed glass vessel (under N2 purging) was charged with crude product 4 (14.42 kg wet cake) and acetic acid (48.8 L), and the agitator was started. Deionized water (1.74 L) was added. The batch (slurry) temperature was adjusted from 18.1°C to 100.1°C over 4.25 hours. The batch was maintained at 100.1-106.1°C for 1 hour and then adjusted to 73.1°C. Deionized water (28.0 L) was added to the batch over 1 hour while maintaining the batch temperature between 73.1-70.3°C. The batch temperature was further adjusted from 70.3°C to 25.0°C overnight. The batch was filtered using a 24" Hastelloy Nutsche filter equipped with a polypropylene filter cloth. Filtration took 13 minutes. A solution of deionized water (9.00 L) and acetic acid (11.0 L) was prepared and added to a 100 L vessel. The mixture was stirred for 5 minutes and then transferred to the filter cake. Deionized water (20.0 L) was added to the vessel, stirred for 6 minutes, and then transferred to the filter cake.Deionized water (20.0 L) was added to the vessel and stirred for 9 minutes before being transferred to the filter cake. The batch was conditioned for 3 days before being transferred to drying trays for vacuum oven drying. After 3 days at 50°C and 28°C / Hg, the batch yielded 4 as an off-white solid in 74% yield (3.7 kg). 1 The H NMR spectrum was consistent with the assigned structure, HPLC analysis indicated a purity of 98.87%, and KF analysis indicated 0.14% HO.

[0221] Synthesis of Intermediate 7: A 100 L jacketed glass vessel (under N2) was charged with tetrahydrofuran (44.4 L). The agitator was started (125 RPM) and 4 (3.67 kg) was added, followed by lithium chloride (1.26 kg). The batch temperature was measured at 26.7 °C, resulting in an amber solution. While maintaining the batch at 24.3-33.6 °C, a solution of 1.64 mol of isopropenyl magnesium bromide in 2-methyl THF (21.29 kg) was added over 2.5 hours. The batch was stirred at 24.5 °C for 17 hours, at which point HPLC analysis indicated 9% 4. A second 100 L jacketed glass vessel (under N2) was charged with 3N hydrogen chloride (18.3 L). The batch was transferred to a vessel containing 3N HCl over 25 minutes, maintaining the batch temperature at 20-46 °C. A two-phase solution was observed. The quenched batch was returned to the first 100 L vessel to quench any remaining small amounts of residue. THF (2.00 L) was used as a rinse. The batch temperature was noted to be 40.9°C and stirred at 318 RPM for 45 minutes. The batch temperature was adjusted to 21.8°C and the layers were allowed to separate. Separation took 10 minutes. The lower aqueous phase was discarded (~26.0 L). A solution of sodium chloride (1.56 kg) in deionized water (14.0 L) was prepared and added to the batch. This was stirred at 318 RPM for 10 minutes, and the agitator was stopped. Separation took 3 minutes. The lower aqueous phase was discarded (~16.0 L). The batch was vacuum distilled from 58.0 L to 18.4 L using ~24" / Hg and a jacket temperature of 50-55°C. A solution of potassium hydroxide (2.30 kg) in deionized water (20.7 L) was prepared in a 72 L round bottom flask. The vessel was set up for atmospheric distillation using two distillation heads and the batch was transferred to the 72 L vessel. THF (0.75 L) was used as a rinse. The batch volume was ~41.0 L, the temperature was adjusted to 64.1°C and distillation began with a N2 sweep. Heating was continued under distillation to bring the batch temperature to 85.4°C, at which point the 72 L vessel was set up for reflux (the batch volume at the end of the distillation was approximately 28.0 L). The batch was held at 85°C for 13 hours, at which point HPLC analysis showed 0.3% Compound 6A. Heating was stopped and the batch was transferred to a 100 L jacketed glass vessel. Solids were observed.The batch temperature was adjusted from 70.6°C to 56.7°C. A previously prepared solution of sodium bicarbonate (2.82 kg) in deionized water (35.0 L) was added over 80 minutes while maintaining the batch temperature between 56.7°C and 46.7°C. The batch pH was 9.8 at the end of the addition. The batch was maintained at 46.7°C and 49.0°C for 40 minutes and then cooled to 25.0°C. The batch was filtered using an 18" stainless steel Nutsche filter. Deionized water (18.4 L) was added to the vessel and transferred to the filter. The filter cake was manually resuspended in the filter, and the liquid was discarded. This process was repeated once more, resulting in a filter cake 3" thick. The filter cake was conditioned on the filter for 3 days, transferred to a drying tray, and dried in a vacuum oven at 45°C to yield 2.93 kg of Intermediate 7 (95% yield) with an HPLC purity of 87.6%.

[0222] Synthesis of Intermediate 8: Acetic acid (13.0 L) was charged to a 100 L jacketed glass vessel (connected to a caustic soda scrubber under N2 purging). Intermediate 7 (2.85 kg) was added to the vessel and the agitator was started. N-cyanoacetylurethane (1.56 kg) and deionized water (5.70 L) were added to the vessel. The batch temperature was adjusted from 17.0 °C to 5.5 °C, and a thin slurry was observed. At this point, 37% hydrogen chloride (2.70 L) was added over 10 minutes while maintaining the batch temperature between 4.8 °C and 8.8 °C. A previously prepared solution of sodium nitrite (638 g) in deionized water (1.42 L) was added over 26 minutes while maintaining the batch temperature between 5.8 °C and 8.7 °C. A brown gas was observed in the vessel headspace during the addition. No Intermediate 7 was detected by HPLC analysis. At this point, a previously prepared solution of sodium acetate (2.07 kg) in deionized water (8.50 L) was added over 47 minutes while maintaining the batch temperature between 5.5°C and 9.5°C. After the addition, a thin layer of orange residue was observed on the vessel wall just above the batch level. The batch temperature was adjusted from 9.4°C to 24.5°C and maintained at 25°C (±5°C) for 12 hours. The batch was filtered using a 24" Hastelloy Nutsche filter fitted with a polypropylene filter cloth. Filtration took 30 minutes. The vessel was rinsed with 14.3 L of 1:1 acetic acid / deionized water. Any remaining orange residue in the reaction vessel was washed away with the rinse. The rinse was transferred to the filter and the batch was manually resuspended. Vacuum was again applied to remove the wash. A second 1:1 acetic acid / deionized water wash was performed as above and the batch was conditioned on the filter for 26 hours. HPLC analysis of the wet filter cake showed a purity of 90.4%. The batch was dried in a vacuum oven at 45°C and 28" / Hg to a constant weight of 3.97 kg (91% yield).

[0223] Preparation of DMAC solvate of compound A A 100 L jacketed glass vessel under N2 was charged with Intermediate 8 (3.90 kg) and potassium acetate (875 g). N,N-Dimethylacetamide (DMAC, 18.3 L) was added to the vessel and the agitator was started. The batch temperature was adjusted to 115°C over 2 hours. After 2 hours at 115°C, the batch was sampled and analyzed by HPLC, which indicated 0.27% of Intermediate 8 remained. The batch temperature was adjusted to 25.0°C overnight. Acetic acid (975 mL) was added to the batch and the batch was stirred for an additional 3 hours. The batch was transferred to a carboy and the vessel was rinsed with 800 mL of DMAC. The batch was returned to the 100 L vessel through a 10 μm in-line filter using vacuum, using a DMAC rinse (1.15 L). Filtration was rapid at the beginning but slowed to a clog at the end, causing the filter to clog. The batch temperature was adjusted to 11.1°C and deionized water (35.1 L) was added over 2 hours and 20 minutes while maintaining the batch temperature between 5-15°C. The batch was held for 1 hour and then filtered using an 18" Nutsche filter fitted with a tightly woven polypropylene filter cloth. Filtration took 15 hours. A 1:1 ethanol / deionized water wash (19.5 L) was added to the vessel, cooled to 10°C, and transferred to the filter cake. The cake was conditioned under N2 and vacuum for 8 hours and then transferred to a drying tray. The batch was dried in a vacuum oven at 45°C and 28" / Hg to give an 89% yield (3.77 kg) of the DMAC solvate of compound A as an orange / tan solid. 1 The H NMR spectrum was consistent with the assigned structure, and Karl Fischer analysis indicated 0.49% HO. XRPD indicated the expected form, i.e., DMAC solvate of Compound A. Thermogravimetric analysis (TGA) showed a weight loss of 16%. HPLC analysis indicated a purity of 93.67%.

[0224] Preparation of crude compound A A 100 L jacketed glass vessel under N2 was charged with DMAC solvate of Compound A (3.75 kg) and ethanol (15.0 L). The agitator was started and acetone (15.0 L) was added. The batch temperature was adjusted from 10.6°C to 60.0°C over 1 hour. At this point, the batch was a solution. Deionized water was added to the batch over 1.5 hours while maintaining the batch temperature at 60±5°C. The batch was maintained at 60±5°C for 1 hour and then cooled to 23.5°C. An 18" Nutsche filter equipped with a tightly woven (0.67 CFM) polypropylene filter cloth was set up and the batch was filtered. Filtration took 15 hours. A 1:1 ethanol / deionized water wash (19.5 L) was added to the vessel and transferred to the filter cake. The cake was conditioned under N2 and vacuum for 8 hours and then transferred to a drying tray. The batch was dried in a vacuum oven at 45°C and 28" / Hg for 5 days to give Compound A as a powdery tan solid in 94% yield (2.90 kg). 1 The H NMR spectrum was consistent with the assigned structure, and Karl Fischer analysis indicated 6.6% HO. XRPD indicated the expected dihydrate form. TGA showed a weight loss of 6.7%. HPLC analysis indicated a purity of 96.4% (AUC).

[0225] Purification of crude compound A A 50 L jacketed glass vessel under N2 was charged with crude compound A (2.90 kg) and methyl isobutyl ketone (14.5 L). The agitator was started and the batch temperature was adjusted from 20.2°C to 50.4°C over 1.5 hours. The batch was maintained at 50°C (±5°C) for 1 hour and then cooled to 20-25°C. The batch was maintained at 20-25°C for 2.5 hours. An 18" Nutsche filter equipped with tightly woven (0.67 CFM) polypropylene filter cloth was set up and the batch was filtered. Filtration took 20 minutes. Methyl isobutyl ketone (MIBK, 1.45 L) was added to the vessel and transferred to the filter cake. The cake was manually resuspended and vacuum was applied to remove the liquid. Methyl isobutyl ketone (2.90 L) was added to the filter cake and the cake was manually resuspended. Vacuum was applied to remove the liquid and the cake was conditioned under vacuum and nitrogen for 15 hours. The filter cake was dried and formed into a tan, hard 18" x 1.5" disk. This was crushed by hand and placed through a coffee grinder to give a 76% yield (2.72 kg) of MGL-3196 MIBK solvate as a tan, powdery solid. Oven drying was not necessary. 1 The H NMR spectrum was consistent with the assigned structure, and Karl Fischer analysis indicated <0.1% HO. XRPD indicated the expected MIBK solvate form. TGA showed a weight loss of 17.3%. HPLC analysis indicated a purity of 98.5%.

[0226] Example 6: Conversion of Compound A to Form I Purified Compound A (4802 g) as a 1:1 MIBK solvate, obtained from Intermediate 8 as described in Example 5 above, was charged to a 100 L jacketed reaction vessel along with 24 L of ethanol. The resulting slurry was heated to 80±5°C (reflux) over 1 hour 25 minutes, and the mixture was stirred at this temperature for 4 hours 25 minutes. Analysis of the filtered solid at 2 hours 55 minutes indicated complete conversion with an XRPD spectrum consistent with Form I. The mixture was cooled to 20±5°C over 45 minutes and stirred at this temperature for 15 minutes. The slurry was filtered, and the filter cake was washed twice with pre-filtered ethanol (2×4.8 L). The wet cake (4.28 kg) was dried under vacuum at 40±5°C for 118 hours to provide 3390 of Compound A Form I.

[0227] Powder X-ray diffraction studies were performed on various lots of Compound A Form I prepared by the above method. XRPD after micronization confirms Form 1.

[0228] Data for Form I is shown below in Table 11 and the diffractogram for Form I is shown as Figure 1.

[0229] [Table 15] TIFF2025179154000039.tif233161TIFF2025179154000040.tif20161

[0230] DSC revealed that Form I has an onset of melting at around 321°C and decomposes after melting (Figure 2).

[0231] Example 7: Preparation of Compound A Form I: Conversion of Compound A Solvate to Form I A 50 L jacketed glass vessel under N2 was charged with the MIBK solvate of Compound A from Example 5 above (2.72 kg) and ethanol (13.6 L). The agitator was started and the batch temperature was adjusted from 16.8°C to 79.4°C over 1.3 hours. The batch was held at 79.5°C for 2 hours and then sampled for XRPD analysis. XRPD indicated Form I, so the batch was cooled to 24.9°C over 1 hour and 10 minutes. An 18" Nutsche filter equipped with tightly woven (0.67 CFM) polypropylene filter cloth was set up and the batch was filtered. Filtration took 4 minutes. Ethanol (2.8 L) was added to the vessel and transferred to the filter cake. The cake was manually resuspended and vacuum was applied to remove the liquid. Ethanol (2.80 L) was added to the filter cake and the cake was manually resuspended. Vacuum was applied to remove the liquid and the cake was conditioned under vacuum and nitrogen for 1 hour. The filter cake was transferred to a drying pan and dried at 45°C and 28" / Hg for 1 day to give Compound A as a pale yellow solid in 89% yield (1.96 kg). HPLC analysis indicated a purity of 99.6%. XRPD analysis was consistent with Form I. 300 g of this material was milled in a 2" jet mill to give 284 g (95% yield) of finely powdered Compound A. XRPD analysis confirmed that the finely powdered Compound A remained Form I.

[0232] The DMAC solvate of Compound A can be converted to Form I via the dihydrate and MIBK solvate as described in Example 7. Alternatively, the DMAC solvate was converted directly to Form I in 75% yield (calculated from Intermediate 8) by heating with 8 volumes of ethanol to 80° C. for 2 hours, followed by cooling to room temperature and filtration. In a separate reaction, a sample of Compound A that was a mixture of DMAC solvate and dihydrate was converted to Form I in 69% yield by heating with 8 volumes of MIBK to 80° C. and then cooling to room temperature.

[0233] Modeling the interaction of compound A with thyroid hormone receptors Crystal structures (ID numbers: 1N46, 1NQ0, 1NQ1, 1NQ2, and 1NUO) were obtained from the RCSB Protein Data Bank. Protein cocrystal structures were aligned using MacPymol for Mac OS X (Copyright 2006 DeLano Scientific LLC.; now a product of Schrodinger Inc.). MacPymol was also used for the complete ligand-protein interaction analysis, resulting in Figures 3–9. Overall, these figures suggest that compound A can better accommodate the structural changes in THRβ mutants. For example, in the Arg316His mutant, Arg316 is mutated to His, and Arg320 is slightly displaced from the ligand. As a result, the specific interaction between Arg320 and T3 is weakened in the Arg316His mutant. In contrast, the large negatively polarizable heterocycle in compound A forms a favorable interaction that is not disrupted by the Arg316His mutation. In other words, compound A, which has a larger, more polarizable heterocycle, maintains a good interaction between Arg320 and the mutated His316. See, e.g., Figures 8 and 9. The results are similar for the other mutations.

[0234] The table below summarizes the biochemical properties of selected TRβ mutants. For other mutants and their properties, see, e.g., M. Adams et al., J Clin Invest. 1994; 94(2):506-515; BRHuber et al., Mol Endocrinol, 2003, 17(4):643-652; and BRHuber et al., Mol Endocrinol, 2003, 17(1):107-116, each of which is incorporated herein by reference in its entirety.

[0235] [Table 16]

[0236] equivalent The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the foregoing embodiments are to be considered in all respects as illustrative and not limiting of the invention described herein. The scope of the invention is, therefore, indicated by the following claims rather than the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

1. (a) R １ MgX or R １ Li is reacted with a compound of formula (I): 【Chemistry 1】 and contacting the compound of formula (II): 【Chemistry 2】 (wherein R １ is isopropyl or isopropenyl, X is halo, and R ２ is H or an amine protecting group; (b) R １ is isopropenyl, in the presence of a base, or １ When is isopropyl, the compound of formula (II) can be reacted with a compound of formula (III): 【Transformation 3】 A synthesis method comprising the step of converting a compound of formula (I) into a compound of formula (II).

2. (c) the amine protecting group R of the compound of formula (III) ２ 2. The method of claim 1, further comprising the step of removing, if present, 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one.

3. R １ is isopropenyl, and X is Br, and R １ 2. The method of claim 1, wherein step (a) is carried out by contacting MgX with a compound of formula (I).

4. 4. The process of claim 3, wherein step (a) is carried out in THF in a volume to weight ratio of THF to the compound of formula (I) of from 7 to 15.

5. 4. The method of claim 3, wherein step (a) is carried out in the presence of a Lewis acid.

6. 4. The method of claim 3, wherein the Lewis acid is a lithium halide.

7. 10. The method of claim 1, wherein the base in step (b) is a metal hydroxide.

8. 8. The method of claim 7, wherein the metal hydroxide is potassium hydroxide.

9. R １ is isopropyl, and X is Cl, and R １ 2. The method of claim 1, wherein step (a) is carried out by contacting MgX with a compound of formula (I).

10. 10. The process of claim 9, wherein step (a) is carried out in THF in a volume to weight ratio of THF to the compound of formula (I) of from 7 to 30.

11. 10. The method of claim 1, wherein the oxidizing agent in step (b) is bromine and step (b) is carried out in the presence of an acid.

12. R ２ 2. The method of claim 1, wherein is acetyl or benzoyl.

13. R ２ The method of claim 12, wherein is benzoyl.

14. 2. The method of claim 1, further comprising the steps of contacting 3,6-dichloropyridazine with 2,6-dichloro-4-aminophenol to form 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline, hydrolyzing the 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline, and protecting the amine group of the 3,5-dichloro-4-((6-chloropyridazin-3-yl)oxy)aniline before or after hydrolysis to form the compound of formula (I), thereby providing the compound of formula (I).

15. 15. The method of claim 14, further comprising purifying the compound of formula (I) in an acidic solution at a temperature of 80-100°C prior to step (a).

16. 15. The method of claim 14, wherein the step of contacting 3,6-dichloropyridazine with 2,6-dichloro-4-aminophenol is carried out in a polar aprotic solvent in the presence of a base at a reaction temperature of 60 to 120°C.

17. The polar aprotic solvent is dimethylacetamide (DMAC), and the base is Cs ２ CO ３ and the reaction temperature is about 65°C.

18. Furthermore, (d) reacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with a compound of formula (IV): 【Chemistry 4】 [In the formula, R ３ is H or CH ２ R ａ wherein R ａ is a hydroxyl group, O-linked amino acid, -OP(O)(OH) ２ or -OC(O)-R ｂ and R ｂ is a lower alkyl group, an alkoxy group, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or -(CH ２ ) ｎ - a heteroaryl group and n is 0 or 1; R ４ is H; and R ５ is CH ２ COOH, C(O)CO ２ H, or an ester or amide thereof, or R ４ and R ５ together to form -N=C(R ｃ )—C(O)—NH—C(O)—, wherein R ｃ is H or a cyano group.

19. 19. The method of claim 18, wherein the compound of formula (IV) is 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A"), and step (d) is carried out by contacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with ethyl (2-cyanoacetyl)carbamate and a metal nitrite, followed by treatment with potassium acetate in DMAC.

20. 20. The method of claim 19, further comprising forming a form of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A") (Form I), characterized by an X-ray powder diffraction pattern containing peaks at about 2θ = 10.5°, 18.7°, 22.9°, 23.6°, and 24.7°.

21. The compound of formula (IV) is represented by formula (V) 【Transformation 5】 (In the formula, R ３ is CH ２ R ａ 20. The method of claim 18, wherein 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one is a compound of formula (V), and step (d) is carried out by contacting 6-(4-amino-2,6-dichlorophenoxy)-4-isopropylpyridazin-3(2H)-one with ethyl (2-cyanoacetyl)carbamate to form 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A"), and converting Compound A to the compound of formula (V) under appropriate conditions.

22. A form of 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A") (Form I), characterized by an X-ray powder diffraction pattern containing peaks at 2θ=approximately 10.5°, 18.7°, 22.9°, 23.6°, and 24.7°.

23. 23. The form of claim 22, further characterized by a powder X-ray diffraction pattern comprising peaks at about 2θ = 8.2°, 11.2°, 15.7°, 16.4°, 17.7°, 30.0°, and 32.2°.

24. 23. The form of claim 22, characterized by a powder X-ray diffraction pattern substantially similar to that shown in Figure 1.

25. 23. The form of claim 22, wherein the purity of the form is greater than 99%.

26. 23. A pharmaceutical composition comprising the form of claim 22 and a pharmaceutically acceptable carrier. 【Request Item 27】 【Chemistry 6】 and salts thereof.

28. 1. A pharmaceutical composition for the treatment of thyroid hormone resistance (RTH) in a subject in need thereof, comprising a therapeutically effective amount of a compound of formula (IV): 【Transformation 7】 [In the formula, R ３ is H or CH ２ R ａ wherein R ａ is a hydroxyl group, O-linked amino acid, -OP(O)(OH) ２ or -OC(O)-R ｂ and R ｂ is a lower alkyl group, an alkoxy group, an alkyl group, a cycloalkyl group, an aryl group, a heteroaryl group, or -(CH ２ ) ｎ - a heteroaryl group and n is 0 or 1; R ４ is H; and R ５ is CH ２ COOH, C(O)CO ２ H, or an ester or amide thereof, or R ４ and R ５ are combined, and -N=C(R ｃ )—C(O)—NH—C(O)—, wherein R ｃ is H or a cyano group; The pharmaceutical composition, wherein the subject has at least one TRβ mutation.

29. 29. The pharmaceutical composition for treating RTH according to claim 28, wherein the compound is 2-(3,5-dichloro-4-((5-isopropyl-6-oxo-1,6-dihydropyridazin-3-yl)oxy)phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile ("Compound A").

30. 29. The pharmaceutical composition for treating RTH according to claim 28, wherein the subject has obesity, hyperlipidemia, hypercholesterolemia, diabetes, non-alcoholic steatohepatitis, fatty liver, bone disease, thyroid system degeneration, atherosclerosis, cardiovascular disorder, tachycardia, hyperactive behavior, hypothyroidism, goiter, attention deficit hyperactivity disorder, learning disability, mental retardation, hearing loss, delayed bone age, neurological or psychiatric disease, or thyroid cancer.

31. 29. The pharmaceutical composition for treating RTH according to claim 28, wherein the TRβ mutation is selected from the group consisting of: a substitution of the wild-type residue alanine (A) at amino acid position 234 of SEQ ID NO: 1 with threonine (T) (A234T); a substitution of the wild-type residue arginine (R) at amino acid position 243 of SEQ ID NO: 1 with glutamine (Q) (R243Q); a substitution of the wild-type residue arginine (R) at amino acid position 316 of SEQ ID NO: 1 with histidine (H) (R316H); and a substitution of the wild-type residue alanine (A) at amino acid position 317 of SEQ ID NO: 1 with threonine (T) (A317T).

32. 23. A method of manufacturing a process according to claim 22, comprising the steps of: heating a mixture comprising a solvent and a sample containing Compound A to a first temperature; 23. The method of claim 22, comprising cooling the mixture to a second temperature lower than the first temperature to obtain the form of claim 22, wherein the solvent is selected from ethanol, isopropanol, methyl isobutyl ketone, and combinations thereof.

33. 33. The method of claim 32, wherein the first temperature is from about 60°C to about 80°C.

34. 34. The method of claim 32 or 33, wherein the second temperature is from about 0°C to about 60°C.

35. 35. The method of claim 34, wherein the second temperature is from about 40°C to about 60°C.

36. 35. The method of claim 34, wherein the solvent is ethanol or methyl isobutyl ketone.

37. 34. The method of claim 32 or 33, wherein the sample containing compound A comprises a solvate of compound A.

38. 38. The method of claim 37, wherein the solvate of Compound A is an ethanol solvate, a methyl isobutyl ketone solvate, an N,N-dimethylacetamide solvate, or a hydrate.

39. 34. The method of claim 32 or 33, further comprising, after cooling the mixture, filtering the mixture to obtain a filter cake.

40. 40. The method of claim 39, further comprising, after filtering the mixture, rinsing the filter cake with an organic solvent to obtain a rinsed filter cake.

41. 41. The method of claim 40, wherein the organic solvent is an alcohol.

42. 42. The method of claim 41, wherein the alcohol is ethanol.

43. 42. The method of claim 41, further comprising, after rinsing the filter cake, drying the rinsed filter cake to obtain Compound A Form I.

44. 44. The method of claim 43, wherein the rinsed filter cake is dried.

45. 45. Form I of Compound A prepared by the process of claim 44.

46. 46. ​​Form I of claim 45, which is substantially free of solvates of Compound A.

47. 46. ​​Form I according to claim 45, wherein the purity is 95% or greater.

48. 46. ​​Form I of claim 45, wherein the solvate of Compound A is about 5% or less.

49. 23. A method of manufacturing a process according to claim 22, comprising the steps of: heating a mixture comprising a solvent selected from ethanol, isopropanol, methyl isobutyl ketone, and combinations thereof and a sample containing Compound A to a first temperature; cooling the mixture to a second temperature that is lower than the first temperature; filtering the mixture to obtain a filter cake; rinsing the filter cake with an organic solvent to obtain a rinsed filter cake; drying the rinsed filter cake to obtain the form of claim 22. The method comprising:

50. 23. A method of manufacturing a composition according to claim 22, comprising the steps of: heating a mixture comprising ethanol and a sample containing Compound A to a first temperature; cooling the mixture to a second temperature that is lower than the first temperature and greater than about 40°C; filtering the mixture at a temperature of 40°C or higher to obtain a filter cake; rinsing the filter cake with ethanol at a temperature of about 40°C or higher to obtain a rinsed filter cake; drying the rinsed filter cake at a temperature of about 40° C. or higher to obtain the form of claim 22. The method comprising:

51. 51. Form I of Compound A prepared by the process of claim 50.

Images