Thieno[3,2-b]pyridine derivatives

Abstract

The present invention relates to a compound of formula (I) (wherein R 1 ~R 4 And A1 are as defined in the specification and claims. Compounds of formula (I) may be used as pharmaceuticals. TIFF2026514800000044.tif34169

Description

[Technical Field]

[0001] The present invention relates to novel organic compounds useful for the treatment and / or prevention in mammals, particularly compounds that reduce huntingtin (HTT) protein levels and are useful for the treatment of Huntington's disease.

[0002] In particular, the present invention relates to the compound of formula (I). [ka] (In the formula, R 1 and R 2 These are independently selected from hydrogen and alkyl, or R 1 and R 2 These, together with the carbon atoms to which they are bonded, form a cycloalkyl group. R 3 is hydrogen, halogen, alkyl, alkoxy, haloalkyl or haloalkoxy, R 4 is hydrogen, alkyl, or halogen, A 1 (is -N- or -CH-), Or relating to pharmaceutically acceptable salts thereof. [Background technology]

[0003] Huntington's disease (HD) is a hereditary autosomal dominant neurodegenerative disorder caused by an elongation of the CAG base repeat in the huntingtin (HTT) gene. Several pieces of evidence suggest that the mutated HTT gene, along with its gene product, the mHTT protein, contributes to the pathogenesis of HD through a toxic gain-of-function mechanism.

[0004] Triplet repeat elongation in exon 1 of the HTT gene is translated into polyglutamine repeats in the HTT protein, making it prone to misfolding and aggregation in cells. The exact mechanism by which mutant HTT disrupts cellular function is unknown, but several processes, including disruption of RNA translation, toxic RNA species, protein aggregates, and stress granules, have been implicated.

[0005] At the neural circuit level, HD has been shown to affect deep brain structures such as the striatum, as well as cortical regions, to varying degrees. Groundbreaking mouse gene experiments combined with human imaging studies have pointed to a crucial role in the corticostriatal connection in the pathogenicity of HD (Wang et al., "Neuronal targets of mutant huntingtin genetic reduction to ameliorate Huntington's disease pathogenesis in mice," Nature Medicine, 20.5(2014):536; Tabrizi et al., "Potential endpoints for clinical trials in premanifest and early Huntington's disease in the TRACK-HD study: analysis of 24-month observational data," The Lancet Neurology 11.1(2012):42-53).

[0006] Hemorrhagic disease (HD) typically develops between the ages of 30 and 50, characterized by numerous symptoms spanning the motor, cognitive, and emotional domains, ultimately leading to death 10 to 20 years after the onset of motor symptoms. While CAG repeat length negatively correlates with the age of motor symptom onset, this accounts for only 50 to 70% of the variability in age of onset. In their efforts to identify genetic modifiers of HD age of onset, Lee et al. (2019, Huntington's disease onset is determined by length of uninterrupted CAG, not encoded polyglutamine, and is modified by DNA maintenance mechanisms. Bioarxiv doi:https: / / doi.org / 10.1101 / 529768) conducted a large-scale genome-wide association study (GWAS) and discovered further genetic modifiers of age of onset.

[0007] Various mouse models have been characterized to model the aspects of HD. YAC128 mice express a full-length mutant HTT transgene with 128 CAG repeats, BACHD mice express a full-length mutant HTT genome sequence with 97 CAG / CAA repeats, and R6 / 2 mice express exon 1 of a mutant human HTT gene with 110–135 CAG repeats. In addition to these mice expressing human transgenes, there are also a series of mouse models, such as the frequently used Q111 and the Q175 knock-in mouse, which has an elongation repeat knocked into the mouse HTT locus.

[0008] There are currently no disease-modifying therapies for Huntington's disease, although several are under development. The underlying disease process behind the syndrome, characterized by motor, cognitive, and behavioral symptoms, remains unaddressed by the various symptomatic treatments currently approved. Tetrabenazine and tiapride are currently approved for the treatment of motor symptoms, i.e., HD-associated chorea. In addition, anticonvulsants, benzodiazepines, antidepressants, and antipsychotics are also used off-label to treat motor, cognitive, and psychiatric symptoms associated with HD.

[0009] Several therapeutic strategies targeting DNA and RNA are being studied to reduce HTT (E.J. Wild, S. Tabrizi, Lancet Neurol. 2017 16(10):837-847). Reducing HTT is a promising therapeutic approach aimed at slowing disease progression by reaching the root cause of Huntington's disease. Reducing HTT is thought to be transformative, preventing major neurodegenerative processes in the brain, when treated in the pre-symptomatic or onset stages of the disease. However, the challenge lies in identifying patients at the appropriate stage of the disease, as the age of onset varies considerably across the population (S.J. Tabrizi, R. Ghosh, BR. Leavitt, Neuron, 2019, 102(4), 899).

[0010] Current clinical approaches are primarily based on antisense oligonucleotides (ASOs). Additionally, a small number of allele-specific reduction strategies, such as SNP (single nucleotide polymorphism)-based ASOs and zinc finger-based gene editing approaches, are being investigated. The use of small molecules to reduce HTT expression has been considered, but this strategy has not yet been validated and has not demonstrated success to date.

[0011] Small molecules offer an opportunity to enable a reduction in HTT in the brain and periphery. Furthermore, small molecule modalities enable access to patient populations that may be difficult to reach with modalities such as ASO or gene therapy. [Overview of the project]

[0012] Therefore, there is a need for novel compounds that can lower mHTT.

[0013] The applicant has surprisingly found that the compounds of the present invention are effective in reducing not only wild-type HTT but also mHTT by modifying the splicing of the aforementioned genes. As a result, the compounds of the present invention are useful in the treatment of HD.

[0014] Importantly, the compounds of the present invention offer favorable selectivity for known off-targets of splicing modifiers and therefore provide a higher therapeutic range compared to non-selective splicing modifiers. One known off-target of small molecule splicing modifiers is, for example, FOXM1, an important cell cycle regulator. Certain undesirable splice variants of FOXM1 include exon 9 (also known as exon A2) insertions, such as variants containing delta C2 and full-length exon A2.

[0015] All publications, patent applications, patents, and other references mentioned herein are incorporated in their entirety by reference.

[0016] In this specification, the term “alkyl” alone or in combination means a linear or branched saturated hydrocarbon group having 1 to 8 carbon atoms, particularly 1 to 6 carbon atoms, and more specifically 1 to 4 carbon atoms. Examples of linear and branched C1-C8 alkyl groups are, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, isomer pentyl, isomer hexyl, isomer heptyl, and isomer octyl. Specific examples of “alkyl” are methyl, ethyl, and isopropyl. Methyl and ethyl are specific examples of “alkyl” in the compounds of formula (I).

[0017] The terms "alkoxy" or "alkyloxy," alone or in combination, refer to the alkyl-O- group of the formula alkyl, in the sense previously given by the term "alkyl." Examples of alkoxys include, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, and tert-butoxy. A specific example of "alkoxy" is methoxy.

[0018] The term "oxy," either alone or in combination, refers to an -O- group.

[0019] The terms "halogen" or "halo," alone or in combination, mean fluorine, chlorine, bromine, or iodine, particularly fluorine, chlorine, or bromine. A preferred example of a halogen is fluorine. The term "halo," in combination with another group, indicates a substitution of the group with at least one halogen, particularly one to five halogens, particularly one to four halogens, i.e., one, two, three, or four halogens, unless otherwise specified.

[0020] The term "haloalkyl" refers, alone or in combination, to an alkyl group substituted with at least one halogen, particularly an alkyl group substituted with 1 to 5 halogens, and particularly an alkyl group substituted with 1 to 3 halogens. Specific "haloalkyl" groups are fluoromethyl, trifluoromethyl, difluoromethyl, fluoroethyl, fluoropropyl, and fluorobutyl. Even more specific "haloalkyl" groups are difluoromethyl and trifluoromethyl.

[0021] The term "pharmaceutically acceptable salt" refers to a salt that retains the biological efficacy and properties of a free base or free acid and is not biologically or otherwise undesirable. Salts are formed using inorganic acids, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, especially hydrochloric acid, and organic acids, such as formic acid, acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, salicylic acid, N-acetylcysteine, and trifluoroacetic acid. Furthermore, these salts can be prepared by adding an inorganic base or organic base to a free acid. Salts derived from inorganic bases include, but are not limited to, salts of sodium, potassium, lithium, ammonium, calcium, and magnesium. Salts derived from organic bases include, but are not limited to, primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, and salts of basic ion exchange resins, such as isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, ethanolamine, lysine, arginine, N-ethylpiperidine, piperidine, and polyamine resins. Compounds of formula (I) can also exist in zwitterionic form. Particularly preferred pharmaceutically acceptable salts of compounds of formula (I) are those formed with formic acid, trifluoroacetic acid, or hydrochloric acid.

[0022] If one of the starting materials of the present invention or the compounds of formula (I) contains one or more functional groups that are not stable or are reactive under the reaction conditions of one or more reaction steps, appropriate protecting groups (e.g., described in “Protective Groups in Organic Chemistry” by T.W. Greene and P.G.M. Wuts, 3rd Ed., 1999, Wiley, New York) can be introduced before an important step of applying a method well-known in the art. Such protecting groups can be removed at a later stage of synthesis using standard methods described in the literature. Examples of protecting groups are tert-butoxycarbonyl (Boc), trityl (Trt), 2,4-dimethoxybenzyl (Dmb), 9-fluorenylmethyl carbamate (Fmoc), 2-trimethylsilylethyl carbamate (Teoc), carbobenzyloxy (Cbz), and p-methoxybenzyloxycarbonyl (Moz). A specific example of a protecting group is tert-butoxycarbonyl (Boc).

Embodiments for Carrying out the Invention

[0023] Certain embodiments of the present invention relate to compounds of formula (I) described herein or pharmaceutically acceptable salts thereof, wherein at least one substituent contains at least one radioisotope. Specific examples of radioisotopes are 2 H, 3 H, 13 C, 14 C and 18 F.

[0024] Furthermore, the present invention includes compounds of formula (I) described herein or pharmaceutically acceptable salts thereof, which contain at least one radioisotope. Specific examples of radioisotopes are 2 H, 3 H, 13 C, 14 C and 18 F.

[0025] Furthermore, the present invention includes, where applicable, all optical isomers of the compounds of formula (I), namely diastereomers, diastereomer mixtures, racemic mixtures, all their corresponding enantiomers and / or tautomers, and solvated compounds thereof.

[0026] Compounds of formula (I) may contain one or more chiral centers and therefore may exist as racemates, racemic mixtures, single enantiomers, diastereomer mixtures, and individual diastereomers. Depending on the properties of various substituents on the molecule, additional chiral centers may be present. Each of these chiral centers independently produces two optical isomers, and all possible optical isomers and diastereomers as mixtures and pure or partially purified compounds are intended to be included in the present invention. The present invention means that it encompasses all such isomeric forms of these compounds. The independent synthesis of these diastereomers or their chromatographic separation can be achieved as known in the art by appropriately modifying the methods disclosed herein. Their absolute stereochemistry can be determined by X-ray crystallography of crystalline products or crystalline intermediates derivatized with reagents containing chiral centers of known absolute configuration, if necessary. If necessary, racemic mixtures of the compounds can also be separated to isolate the individual enantiomers. The separation can be carried out by methods known in the art, such as enantiomerically coupling a racemic mixture of compounds with pure compounds to form a diastereomer mixture, and then separating the individual diastereomers by standard methods such as fractional recrystallization or chromatography.

[0027] The term "chiral carbon atom" refers to a carbon atom having four different substituents. According to the Kahn-Ingold-Prelogue priority rule, a chiral carbon atom can have an "R" or "S" stereoconfiguration.

[0028] Therefore, the present invention also relates in particular to the following. R 1 and R 2 Both are hydrogen, or R1 and R 2 However, the compounds according to the present invention, which together with the carbon atoms to which they are bonded, form a cycloalkyl group. R 1 and R 2 Both are hydrogen, or R 1 and R 2 However, together with the carbon atoms to which they are bonded, they form a cyclopropyl compound according to the present invention. R 1 and R 2 The compound according to the present invention, in which both parts are hydrogen. R 1 and R 2 However, the compounds according to the present invention, which together with the carbon atoms to which they are bonded, form a cycloalkyl group. R 1 and R 2 However, together with the carbon atoms to which they are bonded, they form a cyclopropyl compound according to the present invention. R 3 The compound according to the present invention is hydrogen, methyl, methoxy, fluoro, trifluoromethyl, difluoromethoxy, or trifluoromethoxy. R 3 The compound according to the present invention, wherein is hydrogen, methyl, fluoro, or trifluoromethyl R 3 The compound according to the present invention is trifluoromethyl, R 3 A compound according to the present invention, wherein is difluoromethoxy or trifluoromethoxy. R 3 The compound according to the present invention, wherein is methoxy. R 3 The compound according to the present invention, wherein is methyl R 4 The compound according to the present invention, wherein is hydrogen, methyl, fluoro, or chloro R 4 The compound according to the present invention, wherein is methyl R 4 The compound according to the present invention, wherein is chloro, A1 is -N-, a compound according to the present invention, A1 is -CH-, a compound according to the present invention, Compounds of formula (I) according to the present invention, selected from the following: 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine-6-yl]-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 6-(2,8-dimethylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, and 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof, Compounds of formula (I) according to the present invention, selected from the following: 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine-6-yl]-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 6-(2,8-dimethylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, and 2-(4-azaspiro[2.5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine or a pharmaceutically acceptable salt thereof.

[0029] In one embodiment of the present invention, the compound of formula (I) is 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, and 2-(4-azaspiro[2.5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine or a pharmaceutically acceptable salt thereof.

[0030] In one embodiment of the present invention, the compound of formula (I) is 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0031] In one embodiment of the present invention, the compound of formula (I) is 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-[rac-(7S)-4-azaspiro[2.5]octan-7-yl]thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0032] In one embodiment of the present invention, the compound of formula (I) is 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-[rac-(7R)-4-azaspiro[2.5]octan-7-yl]thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0033] In one embodiment of the present invention, the compound of formula (I) is 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0034] In one embodiment of the present invention, the compound of formula (I) is 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0035] In one embodiment of the present invention, the compound of formula (I) is It is 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine.

[0036] In one embodiment of the present invention, the compound of formula (I) is It is 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine.

[0037] In one embodiment of the present invention, the compound of formula (I) is It is 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine.

[0038] In one embodiment of the present invention, the compound of formula (I) is 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0039] In one embodiment of the present invention, the compound of formula (I) is 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine.

[0040] In one embodiment of the present invention, the compound of formula (I) is 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine.

[0041] In one embodiment of the present invention, the compound of formula (I) is 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine.

[0042] In one embodiment of the present invention, the compound of formula (I) is 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0043] In one embodiment of the present invention, the compound of formula (I) is 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, or a pharmaceutically acceptable salt thereof.

[0044] In one embodiment of the present invention, the compound of formula (I) is 2-(4-azaspiro[2.5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine or a pharmaceutically acceptable salt thereof.

[0045] The synthesis of the compound of formula (I) can be achieved, for example, according to the following scheme: R 1 ~R 4 And A1 are as defined above unless otherwise specified. Scheme 1 [ka]

[0046] The derivatives of general formula I can be prepared according to general scheme 1. Cyclomerizing tert-butyl N-(3-thienyl)carbamate (1) and 2-bromopropanedial (2) at high temperature yields intermediate 6-bromothieno[3,2-b]pyridine 3. Intermediate 3 is lithiated in a suitable solvent such as tetrahydrofuran to produce intermediate 6-bromo-2-iodothieno[3,2-b]pyridine 4. Intermediates of formula 7 are obtained by sequential treatment of a compound of the ketone of formula 5, for example, with an organic base such as lithium diisopropylamide or lithium bis(trimethylsilyl)amide and an electrophilic reactant of formula 6, according to methods known in the art. Boronic acid esters of formula 9 are obtained by borylation of intermediate 7 with bis(pinacorato)diboron (8). Suzuki coupling of 4 and 9 under suitable conditions yields intermediate 10. Subsequent Suzuki coupling of intermediate 10 with a suitable boronic acid 11 yielded the intermediate of formula 12. Next, the obtained intermediate 12 was readily hydrogenated with Pd / C and H2 to obtain derivative 13. By BOC deprotection using a method known in the art, a compound of general formula I was obtained. Scheme 2 [ka]

[0047] Alternatively, the derivatives of general formula I can be prepared according to general scheme 2. Cyclomerizing N-(5-bromo-3-thienyl)carbamate tert-butyl ester (14) and 2-chloropropanedial (15) at high temperature yields 2-bromo-6-chlorothieno[3,2-b]pyridine intermediate 16. Suzuki coupling of 16 and 9 under appropriate conditions yields the intermediate of formula 17. Subsequent Suzuki coupling of intermediate 17 with a suitable boronic acid 11 yields the intermediate of formula 12. Suitable boronic acids for boronic acid 11 include pinacolatoborone and methyliminodiacetic acid (MIDA) boronate, and BF3K is also a suitable boronic acid. The resulting intermediate 12 is then readily hydrogenated with Pd / C and H2 to obtain derivative 13. Compounds of general formula I can be obtained by BOC deprotection using methods known in the art.

[0048] Therefore, the present invention also relates to a process for preparing compounds according to the present invention, comprising the following steps: (a) Compound of formula (B1) [ka] and the compound of formula (B2) [ka] The compounds of formula (B3) are reacted in a suitable solvent in the presence of a base and a suitable palladium catalyst (wherein PG is a suitable protecting group, and in -B(OR)2 each R is independently selected from hydrogen and alkyl, or -B(OR)2 is a suitable dioxavololanyl) to obtain the compound of formula (B3). [ka] The process of obtaining, (b) Hydrogenate the compound of formula (B3) in a suitable solvent, in the presence of hydrogen and a suitable catalyst to obtain the compound of formula (B4). [ka] The process of obtaining, (c) React the compound of formula (B4) in a suitable solvent under suitable conditions to obtain the compound of formula (I). [ka] The present invention also relates to a process comprising at least one of the steps of obtaining, wherein in the above process, PG is a protecting group and A1, R1, R2 and R3 are as described herein.

[0049] In step (a), the solvent may be, for example, 1,4-dioxane, acetonitrile, THF, DMF, or a mixture of the mentioned solvent and water.

[0050] In step (a), the base may be, for example, triethylamine, Na2CO3, or K2CO3.

[0051] In step (a), the palladium catalyst may be, for example, Pd(dppf)Cl2 or XPhosPd G3.

[0052] In step (a), dioxaboloranil is optionally substituted with 1 to 4 substituents independently selected from methyl, ethyl, and isopropyl. In step (a), dioxaboloranil may be, for example, pinacolatoborone or methyliminodiacetic acid (MIDA) boronate. In step (a), B(OR)2 may be BF3K.

[0053] Preferably, the reaction in step (a) is carried out at about 70 to 130°C, particularly about 80 to 120°C, the solvent is a mixture of 1,4-dioxane and water, the base is K2CO3 or triethylamine, and the palladium catalyst is Pd(dppf)Cl2 or XPhos Pd G3.

[0054] In step (b), the solvent may be, for example, SiO, EtOH, MeOH, THF, or a mixture thereof.

[0055] In step (b), the catalyst may be, for example, Pd / C, Pt / C, or PtO2.

[0056] Preferably, the reaction in step (b) is carried out at about 10 to 70°C, particularly about 20 to 60°C, with dimethyl solvent and Pd / C catalyst.

[0057] In step (c), the solvent may be, for example, 1,4-dioxane, SiO, THF, MeOH, EtOH, water, or a mixture thereof. The solvent may also be DCM depending on the structure of the protecting group.

[0058] In step (c), suitable conditions may be, for example, a suitable acid or a suitable base.

[0059] Preferably, in step (c), the solvent is a suitable organic solvent such as 1,4-dioxane or DCM, and the acid is HCl or TFA.

[0060] Preferably, in step (c), the solvent is a suitable organic solvent, and the base is a suitable organic base, such as a primary or secondary amine, and in particular the base is piperidine.

[0061] In the above process, the protecting group may be, for example, BOC, TRT, FMOC, TEOC, DMB, CBZ, or MOZ, particularly BOC.

[0062] The present invention also relates to compounds according to the present invention as they are produced according to the process of the present invention.

[0063] Therefore, the present invention is particularly as follows: Compounds according to the present invention for use as therapeutically active substances, A pharmaceutical composition comprising a compound according to the present invention and a therapeutically inert carrier, Compounds according to the present invention for use in the treatment or prevention of neurodegenerative diseases, Compounds according to the present invention for use in the treatment or prevention of Huntington's disease, Use of the compounds according to the present invention for the treatment or prevention of neurodegenerative diseases, particularly Huntington's disease. Use of the compounds according to the present invention for the preparation of medicines for the treatment or prevention of neurodegenerative diseases, particularly Huntington's disease. A method for treating or preventing neurodegenerative diseases, particularly Huntington's disease, comprising administering an effective amount of the compound according to the present invention to a patient in need thereof, and A method for reducing mutant HTT, comprising administering an effective amount of the compound according to the present invention to a patient in need thereof. This also relates to that.

[0064] Specific embodiments of the present invention relate to pharmaceutical compositions comprising a compound of formula (I) described herein or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable auxiliary substance.

[0065] Furthermore, the structures shown herein also mean that they include compounds that differ only in the presence of one or more isotopically enriched atoms. For example, if one or more hydrogen atoms are replaced with deuterium (2H), or if one or more carbon atoms are replaced with 13C or 14C enriched carbon, it falls within the scope of the present invention.

[0066] Furthermore, the present invention includes all optical isomers of the compound of formula (I), namely diastereomers, diastereomer mixtures, racemic mixtures, all their corresponding enantiomers and / or tautomers, and, where applicable, their solvated compounds.

[0067] Compounds of formula (I) may contain one or more chiral centers and therefore may exist as racemates, racemic mixtures, single enantiomers, diastereomer mixtures, and individual diastereomers. Depending on the properties of various substituents on the molecule, additional chiral centers may be present. Each of these chiral centers independently produces two optical isomers, and all possible optical isomers and diastereomers as mixtures and pure or partially purified compounds are intended to be included in the present invention. The present invention means that it encompasses all such isomeric forms of these compounds. The independent synthesis of these diastereomers or their chromatographic separation can be achieved as known in the art by appropriately modifying the methods disclosed herein. Their absolute stereochemistry can be determined by X-ray crystallography of crystalline products or crystalline intermediates derivatized with reagents containing chiral centers of known absolute configuration, if necessary. If necessary, racemic mixtures of the compounds can also be separated to isolate the individual enantiomers. The separation can be carried out by methods known in the art, such as enantiomerically coupling a racemic mixture of compounds with pure compounds to form a diastereomer mixture, and then separating the individual diastereomers by standard methods such as fractional recrystallization or chromatography.

[0068] In embodiments, where optically pure enantiomers are provided, an optically pure enantiomer means that the compound contains more than 90% by weight of the desired isomer, more specifically more than 95% by weight of the desired isomer, or more specifically more than 99% by weight of the desired isomer, where the weight percentage is based on the total weight of one or more isomers of the compound. Chiralally pure or chiralally concentrated compounds can be prepared by chiral selective synthesis or by separation of enantiomers. Separation of enantiomers can be performed on the final product or on a suitable intermediate.

[0069] Furthermore, one embodiment of the present invention is a compound of formula (I) described herein, when produced by any one of the steps described herein.

[0070] Compounds of formula (I) or pharmaceutically acceptable salts thereof can be used as pharmaceuticals (for example, in the form of pharmaceutical formulations). Pharmaceutical formulations of the present invention can be administered orally (for example, in the form of tablets, coated tablets, sugar-coated tablets, hard and soft gelatin capsules, solutions, emulsions, or suspensions), intranasally (for example, in the form of nasal sprays), rectally (for example, in the form of suppositories), or topically (for example, in the form of solutions, ointments, gels, or water-soluble polymer inserts). However, administration can also be parenterally, such as intramuscularly, intravenously, or intraocularly (for example, in the form of sterile injection solutions).

[0071] Compounds of formula (I) or pharmaceutically acceptable salts thereof can be processed with pharmaceutically inert inorganic or organic adjuvants for the manufacture of tablets, coated tablets, sugar-coated tablets, hard gelatin capsules, injections, or topical preparations. Lactose, corn starch or derivatives thereof, talc, stearic acid or salts thereof, etc., can be used as such adjuvants for tablets, sugar-coated tablets, and hard gelatin capsules.

[0072] Suitable adjuvants for soft gelatin capsules include, for example, vegetable oils, waxes, fats, semi-solid substances, and liquid polyols.

[0073] Suitable adjuvants for the production of solutions and syrups include, for example, water, polyols, sucrose, invert sugar, and glucose.

[0074] Suitable adjuvants for injection solutions include, for example, water, alcohol, polyol, glycerol, and vegetable oil.

[0075] Suitable adjuvants for suppositories include, for example, natural or hydrogenated oils, waxes, fats, semi-solid or liquid polyols.

[0076] Suitable adjuvants for topical ophthalmic formulations include, for example, cyclodextrin, mannitol, or many other carriers and excipients known in the art.

[0077] Furthermore, pharmaceutical formulations may contain preservatives, solubilizers, viscosity enhancers, stabilizers, humectants, emulsifiers, sweeteners, colorants, flavorings, salts to alter osmotic pressure, buffers, masking agents, or antioxidants. Pharmaceutical formulations may also contain other therapeutically beneficial substances.

[0078] Dosages can vary widely and be adapted to the individual requirements of each specific case. Generally, for oral administration, a daily dose of approximately 0.1 mg to 20 mg per kg of body weight, preferably approximately 0.5 mg to 4 mg per kg of body weight (e.g., approximately 300 mg per person), is preferably divided into 1 to 3 individual doses, which, if appropriate, may consist of equal amounts, for example. For topical administration, the formulation may contain 0.001% to 15% by weight of the drug, and the required dose, which may be between 0.1 and 25 mg, can be administered once a day or once a week, or multiple times a day (2 to 4 times), or multiple times a week. However, it will be clear that the upper or lower limits set forth herein may be exceeded if it is indicated that it is necessary.

[0079] Pharmaceutical composition Compounds of formula (I) or pharmaceutically acceptable salts thereof can be used as therapeutic agents, for example, in the form of pharmaceutical formulations. Pharmaceutical formulations can be administered orally, for example, in the form of tablets, coated tablets, sugar-coated tablets, hard gelatin capsules and soft gelatin capsules, solutions, emulsions, or suspensions. However, administration can also be carried out rectally, for example, in the form of suppositories, or parenterally, for example, in the form of injections.

[0080] Compounds of formula (I) or pharmaceutically acceptable salts thereof can be processed with pharmaceutically inert inorganic or organic carriers for the manufacture of pharmaceutical preparations. Lactose, corn starch or its derivatives, talc, and stearic acid or its salts, for example, can be used as carriers for tablets, coated tablets, sugar-coated tablets, and hard gelatin capsules. Suitable carriers for soft gelatin capsules include, for example, vegetable oils, waxes, fats, semi-solids, and liquid polyols. However, depending on the properties of the active substance, a carrier is usually not required for soft gelatin capsules. Suitable carriers for the manufacture of solutions and syrups include, for example, water, polyols, glycerol, and vegetable oils. Suitable carriers for suppositories include, for example, natural oils or hydrogenated oils, waxes, fats and oils, semi-liquids, or liquid polyols.

[0081] Furthermore, pharmaceutical formulations may contain pharmaceutically acceptable auxiliary substances such as preservatives, solubilizers, stabilizers, humectants, emulsifiers, sweeteners, colorants, flavorings, salts, buffers, masking agents, or antioxidants to alter osmotic pressure. These may also contain other therapeutically beneficial substances.

[0082] The present invention also provides a pharmaceutical product comprising a compound of formula (I) or a pharmaceutically acceptable salt thereof and a therapeutically inert carrier, the method for which the preparation thereof comprises forming a dosage form of the compound of formula (I) and / or a pharmaceutically acceptable salt thereof, and optionally one or more other therapeutically beneficial substances, together with one or more therapeutically inert carriers.

[0083] Dosages can vary over a wide range and must be adjusted to the individual requirements of each specific case. For oral administration, adult doses may range from approximately 0.01 mg to approximately 1000 mg per day of the compound of general formula (I) or a corresponding amount of its pharmaceutically acceptable salt. The daily dose may be administered as a single dose or in divided doses, and may exceed the upper limit if deemed necessary.

[0084] The following examples illustrate, but are not limiting, the present invention and are merely representative examples. For simplicity, the pharmaceutical preparation contains approximately 1 to 500 mg, particularly 1 to 100 mg, of the compound of formula (I). Examples of compositions according to the present invention are as follows.

[0085] Example A Tablets with the following composition are manufactured by the usual method: [Table 1]

[0086] Manufacturing procedure 1. Mix ingredients 1, 2, 3, and 4 and granulate with purified water. 2. Dry the granules at 50°C. 3. Pass the granules through an appropriate grinder. 4. Add ingredient 5, mix for 3 minutes, and compress using a suitable press.

[0087] Example B-1 To manufacture capsules with the following composition: [Table 2]

[0088] Manufacturing procedure 1. Mix ingredients 1, 2, and 3 in a suitable blender for 30 minutes. 2. Add ingredients 4 and 5 and mix for 3 minutes. 3. Fill into appropriate capsules.

[0089] The compound of formula (I), lactose, and corn starch are mixed first in a mixer, and then in a grinder. The mixture is returned to the mixer. Talc is added and mixed thoroughly. The mixture is filled into suitable capsules, such as hard gelatin capsules, by machine.

[0090] Example B-2 To manufacture soft gelatin capsules with the following composition: [Table 3] [Table 4]

[0091] Manufacturing procedure The compound of formula (I) is dissolved in the warm melt of the other components, and the mixture is filled into soft gelatin capsules of the appropriate size. The filled soft gelatin capsules are processed according to the usual procedure.

[0092] Example C To manufacture suppositories with the following composition: [Table 5]

[0093] Manufacturing procedure The suppository mass is melted in a glass or steel container, thoroughly mixed, and cooled to 45°C. Then, the finely powdered compound of formula (I) is added and stirred until completely dispersed. The mixture is poured into suppository molds of appropriate size, left to cool, then the suppositories are removed from the molds and individually wrapped in wax paper or metal foil.

[0094] Example D Prepare an injectable solution with the following composition: [Table 6]

[0095] Manufacturing procedure Dissolve the compound of formula (I) in a mixture of polyethylene glycol 400 and part of sterile water for injection. Adjust the pH to 5.0 with acetic acid. Add the remaining water to adjust the volume to 1.0 ml. Filter the solution, fill the vial with an appropriate excess volume, and sterilize.

[0096] Example E Prepare a sachet with the following composition: [Table 7]

[0097] Manufacturing procedure The compound of formula (I) is mixed with lactose, microcrystalline cellulose, and sodium carboxymethylcellulose, and granulated using a polyvinylpyrrolidone mixture in water. Magnesium stearate and flavoring additives are mixed into the granules, and the mixture is filled into sachets. [Examples]

[0098] Abbreviation: AcOEt: Ethyl acetate, AcOH: Acetic acid, ACN: Acetonitrile, DCM: Dichloromethane, DMAP: 4-Dimethylaminopyridine, DMEM: Dulbecco's modified Eagle medium, DMSO: Dimethyl sulfoxide, ES+: Positive electrospray ionization, Depositphotos: Ethyl acetate, EtOH: Ethanol, FA: Formic acid, FAM: Fluorescein amidite phosphor, FBS: Fetal bovine serum, HEX: Hexachlorofluorescein phosphor, High-performance liquid chromatography, HTRF: Homogeneous time-resolved fluorescence, IPA: Isopropyl alcohol, LDA: Lithium diisopropylamide, LF: Long form, MeOH: Methanol, MS: Mass spectrometry, NF: Standard form, PBS: Phosphate-buffered saline, PCR: Polymerase chain reaction, PPTS: Pyridinium p-toluenesulfonate, QPCR: Quantitative PCR, RM: Reaction mixture, RT: Retention time, RT-qPCR: Reverse transcription quantitative PCR, TEA: Triethylamine, TFA: Trifluoroacetic acid, THF: Tetrahydrofuran.

[0099] The following examples are provided to illustrate the present invention. They should not be considered as limiting the scope of the invention, but rather as representative examples.

[0100] intermediate Preparation of the central core intermediate 6-bromo-2-iodothieno[3,2-b]pyridine [ka] Step 1: 6-bromothieno[3,2-b]pyridine A mixture of tert-butyl N-(3-thienyl)carbamate (CAS No. 19228-91-2) (20.0 g, 100.37 mmol, 1.0 equivalent) and 2-bromomalonaldehyde (16.67 g, 110.4 mmol, 1.1 equivalents) in acetic acid (200 mL) was stirred at 100°C for 20 hours. The reaction mixture was concentrated to dryness, the residue was taken off with siRNA, and the organic matter was washed with aqueous Na2CO3 and saturated brine. Next, the organic matter was separated, dried (MgSO4), and concentrated. The crude product was purified by flash column chromatography (elution with 0-80% siRNA in hexane) to obtain 6-bromothieno[3,2-b]pyridine (3.88 g, 18.12 mmol, yield 18.06%) as a pale yellow solid. MS[M+H] + :214.1.

[0101] Step 2: 6-Bromo-2-iodothieno[3,2-b]pyridine A solution of 6-bromothieno[3,2-b]pyridine (3.88 g, 18.12 mmol, 1.0 equivalent) in THF (20 mL) was cooled to -78°C. Then, LDA (10.87 mL, 21.75 mmol, 1.2 equivalents) was added dropwise to the solution under a nitrogen atmosphere, and the mixture was stirred for a further 0.5 hours. Then, a solution of iodine (5.52 g, 21.75 mmol, 1.2 equivalents) in THF (2 mL) was added dropwise. The reaction mixture was warmed to room temperature and stirred for 1 hour. Then, siRNA was added to the mixture, followed by the addition of H2O. The aqueous layer was extracted with toluene, the combined organic layers were dried (Na2SO4), filtered, concentrated, and the residue purified by flash column chromatography (eluting with 0-60% toluene in hexane) to obtain 6-bromo-2-iodothieno[3,2-b]pyridine (3.3 g, 9.71 mmol, yield 53.56%) as a pale yellow solid. MS[M+H] + :339.9.

[0102] Preparation of the central core intermediate 2-bromo-6-chlorothieno[3,2-b]pyridine [ka] To a solution of N-(5-bromo-3-thienyl)carbamate tert-butyl ester (5 g, 17.97 mmol, 1,000 equivalents) (CAS-Nr:494833-75-9) in methanol (12.5 mL), 53.92 g, 44.94 mL, 179.75 mmol, 10,000 equivalents) of 4 M HCl aqueous solution in 1,4-dioxane was added at room temperature. The mixture was stirred overnight. The solvent was removed under vacuum, and glacial acetic acid (50 mL) was added, followed by 2-chloromalonaldehyde (2.11 g, 19.77 mmol, 1,100 equivalents) (CAS Nr:36437-19-1). The mixture was heated under reflux and stirred for 2 hours. The solvent was evaporated, and the residue was separated into dichloromethane (50 mL) and 1 M Na2CO3 solution (30 mL). The layers were separated. The aqueous layer was extracted twice with 50 ml of dichloromethane. The combined organic layers were dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum to obtain the crude title compound. Purification of the eluate by flash chromatography using n-heptane / ethyl acetate yielded the title compound (2.05 g, 34%) as a grayish-white solid with a purity of 74%. MS[M+H]+: 249.8, 251.8

[0103] Preparation of boronic acid esters and / or boronic acid These derivatives were ultimately obtained in the form of boronic acid esters, boronic acid, or mixtures thereof, and were used directly in subsequent processes.

[0104] Boronic acid ester 1 2,8-dimethyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-b]pyridazine [ka] Prepared in accordance with International Publication No. 2019 / 057740

[0105] Boronic acid ester 2 8-Methoxy-2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-b]pyridazine [ka] Step 1: Preparation of 8-bromo-6-chloro-2-methylimidazo[1,2-b]pyridazine To a solution of (4-bromo-6-chloropyridazine-3-yl)amine (CAS No.: 446273-59-2) (2000 mg, 9.6 mmol) and PPTS (241 mg, 0.96 mmol) in isopropanol (19 mL), 1-bromo-2,2-dimethoxypropane (2.11 g, 1.56 mL, 11.5 mmol) was added at room temperature. The reaction mixture was heated under reflux for 30 hours. After cooling to room temperature, the mixture was separated into ethyl acetate (50 mL) and 1 M Na2CO3 solution (30 mL). The layers were separated, the organic layer was washed once with 30 mL of brine, dried over sodium sulfate, filtered, and concentrated under vacuum to obtain the crude title compound (2.37 g, yield 92%) as a light brown solid with a purity of 92%, which was used without further purification. MS(ES+)m / z:246.0-248.0[(M+H) + ].

[0106] Step 2: Preparation of 6-chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine: In acetonitrile (10 mL), a solution of 8-bromo-6-chloro-2-methylimidazo[1,2-b]pyridazine (500 mg, 2.03 mmol) and cesium carbonate (1.4 g, 4.3 mmol) was added to a mixture of MeOH (400 μL, 9.89 mmol) at room temperature, and the mixture was stirred for 4 hours. The mixture was separated into ethyl acetate (30 mL) and water (30 mL). The combined organic layers were washed once with 30 mL of brine, dried over sodium sulfate, filtered, and concentrated under vacuum. Purification by flash chromatography yielded 6-chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine (337 mg, yield 84%) as a white solid. MS(ES+)m / z:198.0[(M+H)]+ ].

[0107] Step 3: Preparation of 8-methoxy-2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-b]pyridazine: In 1,4-dioxane (1.2 mL), a mixture of 6-chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine (118 mg, 0.597 mmol), bis(pinacolato)diborone (CAS No.: 73183-34-3) (151.5 mg, 0.597 mmol, 1 equivalent), and potassium acetate (150.48 mg, 1.53 mmol) was prepared by adding XPhos Pd G4 (CAS No.: 1599466-81-5) (22 mg, 0.026 mmol). The reaction mixture was heated at 100 °C for 1 hour. The reaction mixture was cooled to room temperature and then diluted with ethyl acetate (5-10 mL). The solid was removed by filtration. The filtrate was concentrated under vacuum to obtain the crude title compound, which was used directly in the next step without further purification. The resulting product may exist as a boronic acid ester, boronic acid, or a mixture thereof.

[0108] Boronic acid ester 3 2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-8-(trifluoromethyl)imidazo[1,2-b]pyridazine [ka] Step 1: Preparation of [6-chloro-4-(trifluoromethyl)pyridazin-3-yl]amine: A mixture of 3,6-dichloro-4-(trifluoromethyl)pyridazine (9.95 g, 45.86 mmol, 1.000 equivalents) and 25% aqueous ammonia solution (31.24 g, 39.69 mL, 458.57 mmol, 10.000 equivalents) in 1,4-dioxane (100 ml) was heated at 50°C for 15 hours. The mixture was separated into ethyl acetate (200 ml) and water (200 ml). The layers were separated. The aqueous layer was extracted once with 200 ml of ethyl acetate. The combined organic layers were washed once with 200 ml of brine, dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum to obtain the crude title compound. The title compound (5.75 g, 63%) was obtained as a white solid by purification by flash chromatography using n-heptane / ethyl acetate as the eluate. MS(ES+)m / z:198[(M+H) + ].

[0109] Step 2: Preparation of 6-chloro-2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine: In a 10 mL round-bottom flask equipped with a magnetic stirring bar, reflux condenser, and N2-inlet bubbler, [6-chloro-4-(trifluoromethyl)pyridazin-3-yl]amine (94 mg, 0.476 mmol) and pyridinium p-toluenesulfonate (11.9 mg, 0.048 mmol) were combined with isopropanol (2 mL). 1-bromo-2,2-dimethoxypropane (104.51 mg, 77.13 μL, 0.571 mmol, 1.2 equivalents) was added, and the colorless solution was stirred at 75°C for 24 hours. The resulting dark brown reaction mixture was cooled to room temperature, diluted with HCl (10 mL), and washed with saturated NaHCO3 aqueous solution (10 mL). The organic layer was separated, dried over sodium sulfate, filtered, and concentrated under vacuum. The crude substance (120 mg of a brownish, viscous oily substance) was purified by column chromatography to obtain 6-chloro-2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine (46 mg, yield 34%) as a pale yellow solid. MS(ES+)m / z:236.1[(M+H) + ].

[0110] Step 3: Preparation of 2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-8-(trifluoromethyl)imidazo[1,2-b]pyridazine: In a 20 mL microwave tube equipped with a magnetic stirring bar and cap septum, running dry / argon, 6-chloro-2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine (300 mg, 1.2 mmol), bis(pinacorato)diborone (364.7 mg, 1.44 mmol), and potassium acetate (352.42 mg, 3.59 mmol) were combined with 1,4-dioxane (12 mL). The yellowish fine suspension was stirred and degassed with argon for 10-15 minutes, after which tetrakis(triphenylphosphine)palladium (CAS number: 14221-01-3) (69.1 mg, 0.060 mmol) was added. The vial was sealed and stirred in a heating block (temperature: 100°C) for 22 hours. Tetrakis(triphenylphosphine)palladium (69 mg, 0.060 mmol) was further added after 90 minutes, 3.5 hours, and 6 hours. The reaction mixture was cooled to room temperature, filtered, and concentrated under vacuum. The amber-colored viscous oily substance was purified by column chromatography to obtain 2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-8-(trifluoromethyl)imidazo[1,2-b]pyridazine (428 mg, 48%) as a yellow viscous oily substance. The obtained product may exist as a boronic acid ester, boronic acid, or a mixture thereof.

[0111] Boronic acid ester 4 2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-b]pyridazine [ka] Prepared in accordance with International Publication No. 2015 / 173181

[0112] Boronic acid ester 5 8-Fluoro-2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-a]pyridine [ka] Prepared in accordance with International Publication No. 2022 / 194802

[0113] Exemplary compounds of the compound of formula (I) Example 1 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine [ka] Step 1: 8-bromo-6-chloro-2-methylimidazo[1,2-b]pyridazine 4-Bromo-6-chloropyridazine-3-amine (CAS No.: 446273-59-2) (5.0 g, 23.99 mmol, 1.0 equivalent) and pyridinium p-toluenesulfonate (0.6 g, 2.4 mmol, 0.1 equivalent) were dissolved in IPA (50 mL), to which 1-bromo-2,2-dimethoxypropane (5.27 g, 28.79 mmol, 1.2 equivalents) was added at room temperature. The mixture was refluxed for 18 hours. The mixture was separated into ethyl acetate (200 ml) and 1 M Na2CO3 aqueous solution (20 ml). After separating the organic phase, it was washed with 30 ml of brine, dried over sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (diluted with HCl / hexane = 1:1) to obtain 8-bromo-6-chloro-2-methylimidazo[1,2-b]pyridazine (4.3 g, 17.44 mmol, yield 72.73%) as a yellow solid. [M+H] + = 246. 1 H NMR (400MHz, DMSO) 1H NMR (400MHz, DMSO) δ8.23(s,1H), 7.85(s,1H), 2.40(s,3H).

[0114] Step 2: 6-Chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine A mixture of 8-bromo-6-chloro-2-methylimidazo[1,2-b]pyridazine (4.3 g, 17.44 mmol, 1.0 equivalent) and Cs2CO3 (12.54 g, 38.34 mmol, 2.2 equivalents) in ACN (50 mL) was mixed with MeOH (2.80 g, 87.40 mmol, 5.0 equivalents) at room temperature. The mixture was stirred at room temperature for 16 hours. The solvent was then evaporated, the residue was diluted with ethyl acetate (100 mL), washed with water (100 mL), dried over sodium sulfate, filtered, concentrated, and the crude product was purified by flash chromatography (diluted with siRNA / hexane = 2:1) to obtain 6-chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine (2.5 g, 12.65 mmol, yield 72.76%) as a grayish-white solid. [M+H] + = 198.

[0115] Step 3: (8-Methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)boronic acid A suspension of 6-chloro-8-methoxy-2-methylimidazo[1,2-b]pyridazine (2.5 g, 12.65 mmol, 1.0 equivalent), bis(pinacolato)diborone (3.85 g, 15.18 mmol, 1.2 equivalents), potassium acetate (2.37 mL, 37.95 mmol, 3.0 equivalents), and Xphos-Pd-G4 (816.43 mg, 0.95 mmol, 0.08 equivalents) in 1,4-dioxane (30 mL) was stirred at 100°C for 3 hours under a nitrogen atmosphere. The solvent was concentrated, and the residue was purified by preparative HPLC (ACN-H2O, gradient: 0-30%) to obtain (8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)boronic acid (1.2 g, 5.79 mmol, yield 45.80%) as a grayish-white solid. [M+H] + = 208.

[0116] Step 4: tert-butyl4-(6-bromothieno[3,2-b]pyridine-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylate To a solution of 6-bromo-2-iodothieno[3,2-b]pyridine (2.5 g, 7.35 mmol, 1.0 equivalent), 1-N-BOC-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-3, 6-dihydro-2H-pyridine (CAS No.: 286961-14-6) (2.27 g, 7.35 mmol, 1.0 equivalent), and Na2CO3 (1.56 g, 14.71 mmol, 2.0 equivalents) in water (5 mL) / toluene (25 mL) / ethanol (25 mL), Pd(PPh3)4 (849.75 mg, 0.74 mmol, 0.1 equivalent) was added, and the mixture was stirred at 70°C for 10 hours under a nitrogen atmosphere. After cooling the mixture, it was diluted with water (200 mL), extracted with DCM (100 mL x 2), washed with brine (100 mL), dried over anhydrous Na2SO4, filtered, concentrated, and the residue purified by silica gel column chromatography (elution with 0-30% siRNA in hexane) to obtain tert-butyl 4-(6-bromothieno[3,2-b]pyridine-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate (1.8 g, 4.55 mmol, yield 61.92%) as a white solid. [M+H] + =395.

[0117] Step 5: tert-butyl 4-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate A solution of tert-butyl 4-(6-bromothieno[3,2-b]pyridin-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylate (500.0 mg, 1.26 mmol, 1.0 equivalent), (8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)boronic acid (785.42 mg, 3.79 mmol, 3.0 equivalent), K2CO3 (523.64 mg, 3.79 mmol, 3.0 equivalent), and Pd(dppf)Cl2 (CAS No.: 72287-26-4) (92.46 mg, 0.13 mmol, 0.1 equivalent) in 1,4-dioxane (10 mL) and water (2.5 mL) was stirred at 90°C for 10 hours under a nitrogen atmosphere. The solvent was evaporated, and the residue was purified by silica gel column chromatography (siRNA / hexane = 1:1) to obtain tert-butyl 4-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate (350 mg, 0.73 mmol, 57.94%) as a pale yellow solid. [M+H] + = 478.

[0118] Step 6: tert-butyl 4-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)piperidine-1-carboxylate To a solution of tert-butyl 4-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate (350.0 mg, 0.73 mmol, 1.0 equivalent) in  (20 mL), Pd / C (350.0 mg, 10%) was added. The resulting mixture was placed in hydrogen and stirred at 50°C under 1.0 atm for 48 hours. The mixture was filtered, the filtrate was concentrated, and the residue was purified by silica gel column chromatography (siRNA / hexane = 2:1) to obtain tert-butyl 4-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate (300.0 mg, 0.63 mmol, yield 85.36%) as a yellow solid. [M+H] + =480.

[0119] Step 7: 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridinformate To a solution of tert-butyl 4-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate (300.0 mg, 0.63 mmol, 1.0 equivalent) in DCM (6 mL), HCl (3.0 mL, 12.0 mmol, 14.39 equivalents, 4 M) in dioxane was added, and the mixture was stirred at 25°C for 1 hour. Next, the solvent was concentrated, and the residue was purified by preparative HPLC (column: Gemini 5μC18 150×21.2mm, ACN-H2O (0.1% FA)) to obtain 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine (120.1 mg, 0.28 mmol, yield 31.42%) as a grayish-white solid. [M+H] + =380. 1H NMR (400MHz, DMSO) δ9.29(d,J=2.1Hz,1H), 9.07(d,J=1.7Hz,1H), 8.33(s,1H), 8.03(d,J=0.8Hz,1H), 7.45(s,1H), 7.32(s,1 H), 4.16(s,3H), 3.26(d,J=12.0Hz,3H), 2.89(t,J=11.5Hz,2H), 2.37(s,3H), 2.12(t,J=15.6Hz,2H), 1.81(d,J=9.3Hz,2H).

[0120] Example 2 6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazine-6-yl]-2-(4-piperidyl)thieno[3,2-b]pyridine [ka] Step 1: 4-[6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate tert-butyl ester [2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]boronic acid (702 mg, 2.87 mmol, 2,000 equivalents, boronic acid ester 3), 4-(6-chlorothieno[3,2-b]pyridin-2-yl)-3, 6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (503 mg, 1.43 mmol, 1,000 equivalents, R 1 and R 2An intermediate (17) in which hydrogen is present, and a mixture of potassium carbonate (792 mg, 5.73 mmol, 4.000 equivalents) in acetonitrile (6 mL) and water (0.7 mL) were mixed with 1,1'-bis(diphenylphosphino)ferrocene-palladium(II) dichloride dichloromethane complex (CAS number: 72287-26-4) (119 mg, 0.144 mmol, 0.100 equivalents) at room temperature. The reaction mixture was heated in a sealed tube at 95°C (on a 95°C heating plate) and stirred for 1.5 hours. The mixture was separated into ethyl acetate (70 mL) and 1 M NaHCO3 solution (40 mL). The layers were separated. The aqueous layer was extracted twice with 50 mL of ethyl acetate. The combined organic layers were washed once with 30 mL of brine and concentrated under vacuum. The crude substance was purified by flash chromatography to obtain the title compound (135 mg, 18%) as a 100% pure yellow solid. [M+H] + = 516.2.

[0121] Step 2: 4-[6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate tert-butyl ester A solution of 4-[6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (135 mg, 0.262 mmol, 1.000 equivalents) in methanol (12 mL) and dichloromethane (12 mL) was degassed by three vacuum / argon cycles. Palladium supported on activated carbon (139 mg, 0.131 mmol, 0.500 equivalents) was added. The reaction mixture was degassed by three vacuum-hydrogen cycles and stirred under a hydrogen atmosphere for 72 hours. The reaction mixture was filtered through a decalite. The filtrate was evaporated under vacuum. The crude substance was purified by flash chromatography to obtain the title compound (73 mg, 54%) as a 100% pure grayish-white solid. [M+H] + = 518.3

[0122] Step 3: 6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]-2-(4-piperidyl)thieno[3,2-b]pyridine To a solution of 4-[6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylic acid tert-butyl ester (73 mg, 0.141 mmol, 1.000 equivalents) in dichloromethane (2 mL), TFA (740 mg, 500 μL, 6.49 mmol, 46.015 equivalents) was added at room temperature. The mixture was stirred for 2 hours. Volatile substances were evaporated. The residue was dissolved in MeOH (1 mL) and neutralized with 1 M Na2CO3 aqueous solution (4 mL). After 1 hour, the precipitate was collected by filtration, washed three times with 3 mL of water, and dried under vacuum to obtain the title compound (43 mg, 73%) as a light brown solid. [M+H] + =418.3

[0123] Example 3 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine [ka] Step 1: tert-butyl 7-(((trifluoromethyl)sulfonyl)oxy)-4-azaspiro[2.5]octa-6-ene-4-carboxylate To a solution of tert-butyl 7-oxo-4-azaspiro[2,5]octane-4-carboxylate (CAS No.: 1892578-21-0) (2.0 g, 8.88 mmol, 1.0 equivalent) in THF, 1 M LiHMDS (CAS No.: 4039-32-1) (9.8 mL, 9.77 mmol, 1.1 equivalent) was added dropwise at -78°C under a nitrogen atmosphere, and the mixture was stirred for approximately 20 minutes. Next, N,N-bis(trifluoromethylsulfonyl)aniline (3.49 g, 9.77 mmol, 1.1 equivalent) was added, and the mixture was stirred at 25°C for 3 hours. Then, siRNA was added to the mixture, followed by the addition of H2O. The aqueous layer was extracted with ethyl acetate, the combined organic layers were dried (Na2SO4), filtered, concentrated, and the residue was purified by flash column chromatography (eluting with 0-60% ethyl acetate in hexane) to obtain tert-butyl 7-(trifluoromethylsulfonyloxy)-4-azaspiro[2.5]octa-6-ene-4-carboxylate (1.5 g, 4.2 mmol, yield 47.28%) as a yellow solid. 1 H NMR (400MHz, DMSO) δ6.13(s,1H), 4.00(s,2H), 2.38(s,2H), 1.39(d,J=4.0Hz,9H), 0.82(d,J=47.4Hz,4H).

[0124] Step 2: tert-butyl7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate A solution of tert-butyl 7-(trifluoromethylsulfonyloxy)-4-azaspiro[2.5]octa-6-ene-4-carboxylate (700.0 mg, 1.96 mmol, 1.0 equivalent), bis(pinacolato)diborone (547.18 mg, 2.15 mmol, 1.1 equivalent), KOAc (383.94 mg, 3.92 mmol, 2.0 equivalent), and Pd(dppf)Cl2 (143.33 mg, 0.2 mmol, 0.1 equivalent) in 1,4-dioxane (10 mL) was stirred at 100°C for 4 hours under a nitrogen atmosphere, and then concentrated to dryness. The crude product was purified by flash column chromatography (elution with 0-60% ethyl acetate in hexane) to obtain tert-butyl 7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (500.0 mg, 1.49 mmol, yield 76.14%) as a brown solid. MS[M+H]+:236.3

[0125] Step 3: tert-butyl7-(6-bromothieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate To a solution of 6-bromo-2-iodothieno[3,2-b]pyridine (250.0 mg, 0.74 mmol, 1.0 equivalent), tert-butyl 7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (246.52 mg, 0.74 mmol, 1.0 equivalent), and Na2CO3 (155.88 mg, 1.47 mmol, 2.0 equivalents) in water (1 mL), toluene (5 mL), and ethanol (5 mL), Pd(PPh3)4 (84.97 mg, 0.07 mmol, 0.1 equivalent) was added, and the mixture was stirred at 70°C for 10 hours under a nitrogen atmosphere. The mixture was cooled, diluted with water (200 mL), extracted with DCM (100 mL x 2), washed with brine (100 mL), dried over anhydrous Na2SO4, filtered, concentrated, and the residue purified by silica gel column (eluted with 0-30% siRNA in hexane) to obtain tert-butyl 7-(6-bromothieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (160.0 mg, 0.38 mmol, yield 51.64%) as a pale yellow solid. MS[M+H]+: 421.1

[0126] Step 4: tert-butyl7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octa-6-ene-4-carboxylate A mixture of tert-butyl 7-(6-bromothieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (140.0 mg, 0.33 mmol, 1.0 equivalent), 8-methoxy-2-methyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)imidazo[1,2-b]pyridazine (192.14 mg, 0.66 mmol, 2.0 equivalent), Pd(dppf)Cl2 (36.47 mg, 0.05 mmol, 0.15 equivalent), and K2CO3 (137.76 mg, 1.0 mmol, 3.0 equivalent) in 1,4-dioxane (2.5 mL) and water (0.5 mL) was stirred at 90°C for 10 hours under a nitrogen atmosphere. The mixture was diluted with ELISA (80 mL) and then washed with 2 × 50 mL of water and 50 mL of saturated brine. The organic matter was pre-dried (MgSO4). The crude product was purified by flash column chromatography (elution with 0-5% MeOH in DCM) to obtain tert-butyl 7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octa-6-en-4-carboxylate (120.0 mg, 0.24 mmol, yield 67.14%) as a yellow solid. MS[M+H] + :504.1

[0127] Step 5: tert-butyl 7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octane-4-carboxylate To a solution of tert-butyl 7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octa-6-en-4-carboxylate (100.0 mg, 0.2 mmol, 1.0 equivalent) in siRNA (20 mL), Pd / C (20 mg, 10%) was added, and the mixture was stirred at 50°C for 24 hours under a hydrogen atmosphere. The mixture was filtered through Celite and then concentrated under vacuum to obtain tert-butyl 7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (80.0 mg, 0.16 mmol, yield 79.68%) as a pale yellow solid. MS[M] + :506.2

[0128] Step 6: 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(4-azaspiro[2.5]octan-7-yl)thieno[3,2-b]pyridinetrifluoroacetic acid (alternative chemical name: 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(4-azaspiro[2.5]octan-7-yl)thieno[3,2-b]pyridine) A solution of tert-butyl 7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (70.0 mg, 0.14 mmol, 1.0 equivalent) in HCl / dioxane (4 M, 2 mL) was stirred at 25°C for 1 hour. The mixture was concentrated and purified by preparative HPLC (Gemini column, 5 μC18, 150 × 21.2 mm (ACN-H2O, 0.1% TFA)) to obtain 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine, 2,2,2-trifluoroacetic acid (22.1 mg, 0.04 mmol, yield 28.45%) as a yellow solid. MS[M+H] + :405.9 1H NMR (400MHz, D2O) δ9.09(s,2H), 7.94(d,J=0.9Hz,1H), 7.39(d,J=6.8Hz,2H), 4.14(s,3H), 3.58-3.45(m,2H), 3.33-3.19(m ,1H), 2.43(s,3H), 2.36(d,J=12.5Hz,2H), 2.04-1.91(m,1H), 1.71(d,J=15.6Hz,1H), 1.08-1.00(m,2H), 0.92-0.82(m,2H).

[0129] Example 4 6-(2,8-dimethylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine [ka] Step 1: 4-[6-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate tert-butyl ester (2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)boronic acid (547 mg, 2.86 mmol, 2.000 equivalents, prepared according to the procedure described in International Publication No. 2019 / 057740), 4-(6-chlorothieno[3,2-b]pyridin-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (503 mg, 1.43 mmol, 1.000 equivalents), and K2CO3 (793 mg, 5.74 mmol, 4.008 equivalents) were mixed in acetonitrile (6 mL) and water (0.7 mL) to which 1,1'-bis(diphenylphosphino)ferrocene-palladium(II) dichloride dichloromethane complex (119 mg, 0.143 mmol, 0.100 equivalents) was added at room temperature. The reaction mixture was heated in a sealed tube at 95°C (on a 95°C heating plate) and stirred for 1.5 hours. The mixture was separated into ethyl acetate (50 ml) and 1 M Na2CO3 solution (30 ml). The layers were separated. The aqueous layer was extracted twice with 50 ml of ethyl acetate. The combined organic layers were washed once with 30 ml of brine and concentrated under vacuum. The crude material was purified by flash chromatography to obtain the title compound (147 mg, 22%) as a pale brown / orange solid with a purity of 95%. MS[M+H] + :462.3

[0130] Step 2: 4-[6-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate tert-butyl ester A solution of 4-[6-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylic acid tert-butyl ester (97 mg, 0.210 mmol, 1.000 equivalents) in methanol (9.7 mL) and dichloromethane (9.7 mL) was degassed by three vacuum / argon cycles. Palladium supported on activated carbon (112 mg, 0.105 mmol, 0.500 equivalents) was added. The reaction mixture was degassed by three vacuum-hydrogen cycles and stirred overnight under a hydrogen atmosphere. The reaction mixture was filtered through Decalite, redissolved in methanol (9.7 mL) and dichloromethane (9.7 mL), and the reaction was restarted. The reaction mixture was filtered through Decalite, and the solvent was evaporated under vacuum. The crude substance was purified by flash chromatography to obtain the title compound (22 mg, 22%) as a light brown solid. MS[M+H] + :464.5

[0131] Step 3: 6-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine To a solution of 4-[6-(2,8-dimethylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylic acid tert-butyl ester (22 mg, 0.047 mmol, 1.000 equivalents) in dichloromethane (2 mL), TFA (740 mg, 500 uL, 6.49 mmol, 136.764 equivalents) was added at room temperature. The mixture was stirred for 2 hours. The volatile substances were evaporated. The residue was dissolved in MeOH (1 mL) and neutralized with 1 M Na2CO3 aqueous solution (4 mL). The mixture was separated into ethyl acetate (30 mL) and 1 M Na2CO3 solution (20 mL). The layers were separated. The aqueous layer was extracted twice with 50 mL of ethyl acetate. The combined organic layers were washed once with 30 mL of saline solution, dried on sodium sulfate, filtered, and concentrated under vacuum. The residue was dissolved in ethyl acetate (3 ml). 4M HCl (119 uL, 0.475 mmol, 10.000 equivalents) was added to 1,4-dioxane. The precipitate was collected by filtration, washed three times with 2 ml of ethyl acetate, and dried under vacuum to obtain the title compound (12 mg, 56%) as a light brown solid (hydrochloric acid). MS[M+H] + :364.3

[0132] Example 5 6-(2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine [ka] Step 1: tert-butyl4-(6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate

[0133] A mixture of tert-butyl 4-(6-bromothieno[3,2-b]pyridin-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylate (200.0 mg, 0.5 mmol, 1.0 equivalent), (2-methylimidazo[1,2-b]pyridazin-6-yl)boronic acid (179.1 mg, 0.6 mmol, 1.2 equivalents), XPhos Pd G3 (CAS No. 1445085-55-1) (42.9 mg, 0.1 mmol, 0.1 equivalent), and triethylamine (153.6 mg, 1.5 mmol, 3.0 equivalents) in 1,4-dioxane (16 mL) and water (4 mL) was stirred at 110°C for 6 hours under a nitrogen atmosphere. The cooled mixture was concentrated, and the residue was purified by combiflush with 3% MeOH in DCM to obtain tert-butyl 4-[6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate (190.0 mg, 0.42 mmol, yield 81.39%) as a yellow solid. MS[M+H] + :447.9. 1 H NMR (400MHz, DMSO) δ9.26(d,J=2.0Hz,1H), 9.03(d,J=1.8Hz,1H), 8.15(t,J=4.6Hz,2H), 7.87(d,J=9.6Hz, 1H), 7.60(s,1H), 6.45(s,1H), 4.09(s,2H), 3.58(d,J=5.2Hz,2H), 2.63(s,2H), 2.43(s,3H), 1.44(s,9H).

[0134] Step 2: tert-butyl 4-(6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)piperidine-1-carboxylate To a solution of tert-butyl 4-[6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridin-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate (170.0 mg, 0.4 mmol, 1.0 equivalent) in ethyl acetate (30 mL), Pd / C (50 mg, 10%) was added at room temperature. The mixture was stirred under a hydrogen atmosphere at 50 °C for 16 hours. The mixture was filtered, and the filtrate was concentrated to obtain tert-butyl 4-[6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridin-2-yl]piperidine-1-carboxylate (130.0 mg, 0.29 mmol, yield 75.37%) as a pale yellow solid. MS[M+H] + :450.0 1 H NMR (400MHz, DMSO) δ9.26(d,J=2.1Hz,1H), 9.04(d,J=1.5Hz,1H), 8.17-8.11(m,2H), 7.86(d,J=9.6Hz,1H), 7.46(s,1H) , 4.06(s,2H), 3.20(t,J=11.2Hz,1H), 2.90(s,2H), 2.42(s,3H), 2.06(d,J=12.4Hz,2H), 1.68-1.51(m,2H), 1.42(s,9H).

[0135] Step 3: 6-(2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(piperidine-4-yl)thieno[3,2-b]pyridine (Alternative chemical name: 6-(2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(piperidine-4-yl)thieno[3,2-b]pyridine) To a 10 mL solution of tert-butyl 4-[6-(2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate (130.0 mg, 0.3 mmol, 1.0 equivalent) in DCM, trifluoroacetic acid (1.0 mL) was added, and the reaction mixture was stirred at 25°C for 1 hour. The solvent was concentrated, and the residue was purified by preparative HPLC (Gemini-C18 150×21.2 mm, 5 μm, acetonitrile / water as eluent, with 0.1% TFA as a modifier) ​​to obtain 6-(2-methylimidazo[1,2-b]pyridazin-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 2,2,2-trifluoroacetic acid (117.0 mg, 0.25 mmol, yield 85.11%) as a yellow solid. MS[M]+:349.9 1 H NMR (400MHz, DMSO) δ9.31(d,J=2.1Hz,1H), 9.13(d,J=1.8Hz,1H), 8.67(s,1H), 8.49-8.30(m,3H), 8.12(d,J=9.6Hz, 1H), 7.51(s,1H), 3.47-3.34(m,3H), 3.08(q,J=12.6Hz,2H), 2.49(s,3H), 2.25(d,J=12.7Hz,2H), 1.99-1.81(m,2H).

[0136] Example 6 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine [ka] Step 1: tert-butyl4-(6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl)-3,6-dihydropyridine-1(2H)-carboxylate A suspension of tert-butyl 4-(6-bromothieno[3,2-b]pyridine-2-yl)-3,6-dihydro-2H-pyridine-1-carboxylate (200.0 mg, 0.51 mmol, 1.0 equivalent), (8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)boronic acid (245.34 mg, 1.26 mmol, 2.5 equivalents), triethylamine (153.3 mg, 1.52 mmol, 3.0 equivalents), and Xphos-Pd-G3 (85.63 mg, 0.1 mmol, 0.2 equivalents) in 1,4-dioxane (8 mL) and water (2 mL) was heated at 100°C for 3 hours under a nitrogen atmosphere. Next, the solvent was concentrated under vacuum, and the residue was purified by silica gel column chromatography (diluted with siRNA / hexane = 1:2) to obtain tert-butyl 4-[6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate (180 mg, 0.38 mmol, yield 76.59%) as a pale yellow solid. MS(ESI), m / z:[M+H] + =465

[0137] Step 2: tert-butyl 4-(6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl)piperidine-1-carboxylate To a 20 mL solution of tert-butyl 4-[6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl]-3,6-dihydro-2H-pyridine-1-carboxylate (180.0 mg, 0.36 mmol, 1.0 equivalent) in siRNA (20 mL), Pd / C (180.0 mg) was added. The resulting mixture was placed in hydrogen and stirred at 50°C under 1.0 atm for 18 hours. The solid was filtered off, and the filtrate was passed through a silica gel column using siRNA / hexane=2:1 to obtain tert-butyl4-[6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate (130.0 mg, 0.28 mmol, yield 86.09%) as a yellow solid. MS(ESI), m / z:C 25 H 27 Calculated values ​​for FN4O2S 、 Molecular weight: 466, measured value RT = 1.17 min, [M+H] + =467.

[0138] Step 3: 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine (Alternative chemical name: 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(piperidyl-4-yl)thieno[3,2-b]pyridine) To a solution of tert-butyl 4-[6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)thieno[3,2-b]pyridine-2-yl]piperidine-1-carboxylate (130.0 mg, 0.32 mmol, 1.0 equivalent) in DCM (6 mL), TFA (2.0 mL) was added, and the mixture was stirred at 25°C for 1 hour. The mixture was concentrated under vacuum, and the residue was purified by preparative HPLC (column: Gemini 5μC18 150×21.2mm, ACN-H2O (0.1% TFA)) to obtain 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine and 2,2,2-trifluoroacetic acid (55.4 mg, 0.12 mmol, yield 33.62%) as a pale yellow oily substance. MS(ESI), m / z:C 20 H 19 FN4S calculated values 、 Molecular weight: 366, measured value RT = 0.83 min, [M+H] + =367. 1H NMR (400MHz, DMSO) δ9.19(d,J=1.2Hz,1H), 9.05(d,J=2.1Hz,1H), 8.86(d,J=1.8Hz,1H), 8.80(d,J=9.7Hz,1H), 8.54(d,J=9.9Hz,1H), 8.22(d,J=1) 1.8Hz,1H), 8.09(d,J=1.4Hz,1H), 7.48(s,1H), 3.48-3.32(m,3H), 3.09( q,J=12.5Hz,2H), 2.50(s,3H), 2.25(d,J=13.3Hz,2H), 1.97-1.84(m,2H).

[0139] Example 7 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine [ka] and Example 8 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine [ka] Step 1: tert-butyl(R)-7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octane-4-carboxylate and tert-butyl(S)-7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octane-4-carboxylate

[0140] Tert-butyl 7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (990 mg, 1.96 mmol) was separated by SFC (Thar prep 80 (CHIRALPAK AS-H 250 mm × 20 mm, 5 μm (40% IPA (NH4OH 0.2%))) to obtain two corresponding enantiomers.

[0141] The first enantiomer to elute (presumably P1) is a pale yellow solid, tert-butyl(R)-7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octane-4-carboxylate (310 mg, 0.61 mmol, yield 26.17%). MS[M]+:405.9 [α] 27.8 D = -8 (c: 0.3g / 100mL, CHCl3)

[0142] The second enantiomer to elute (presumably P2) was tert-butyl(S)-7-(6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octane-4-carboxylate (305 mg, 0.6 mmol, yield 20.6%), which was also a pale yellow solid. MS[M]+:405.9 [α] 28.1 D = +6.67 (c: 0.3g / 100mL, CHCl3)

[0143] Step 2a: 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine (Example 7, presumed enantiomer assignment) A solution of tert-butyl (7R)-7-[6-(8-methoxy-2-methyl-imidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (300.0 mg, 0.59 mmol, 1.0 eq) in DCM (5 mL) was added with 4N HCl / dioxane (5.0 mL, 20.0 mmol, 33.71 eq), and the mixture was stirred at 25 °C for 2 h. Then the solvent was concentrated to dryness, and the residue was triturated with DCM / ACN (6 mL, 5:1) to obtain 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methyl-imidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine, hydrochloride (246.5 mg, 0.56 mmol, yield 91.93%) as a pale yellow solid. MS [M]+: 406.1 [α] 26.1 D = -47.33 (c: 0.3 g / 100 mL, MeOH) 1 H NMR (400 MHz, DMSO) δ 9.96 (s, 1H), 9.49 (d, J = 11.0 Hz, 1H), 9.41 (d, J = 2.0 Hz, 1H), 9.31 (d, J = 1.8 Hz, 1H), 8.47 (s, 1H), 7.98 (s, 1H), 7.54 (s, 1H), 4.32 (s, 3H), 3.57 - 3.36 (m, 2H), 3.11 (dd, J = 22.8, 11.6 Hz, 1H), 2.52 (d, J = 3.2 Hz, 3H), 2.44 (d, J = 12.7 Hz, 1H), 2.31 (d, J = 15.1 Hz, 1H), 2.07 (dd, J = 21.8, 12.6 Hz, 1H), 1.76 - 1.67 (m, 1H), 1.22 - 1.03 (m, 2H), 0.86 (s, 2H).

[0144] Step 2b: 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methyl-imidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine (Example 8, assignment of the presumed enantiomer) To a solution of tert-butyl(7S)-7-[6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (260.0 mg, 0.51 mmol, 1.0 equivalent) in DCM (5 mL), 4N HCl / dioxane (5.0 mL, 20.0 mmol, 38.89 equivalents) was added, and the mixture was stirred at 25°C for 2 hours. Next, the solvent was evaporated to dryness, and the residue was purified by preparative HPLC (Gemini-C18 150×21.2mm, 5μm, ACN-H2O (0.1% FA) 10-15%). The desired fraction was freeze-dried to obtain 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazin-6-yl)thieno[3,2-b]pyridine and formic acid (119.4 mg, 0.26 mmol, yield 50.97%) as a white solid. MS[M]+:406.1 [α] 26.3 D = +48 (c: 0.3g / 100mL, MeOH) 1 H NMR (400MHz, DMSO) δ9.29(s,1H), 9.07(s,1H), 8.14(s,0.5H), 8.03(s,1H), 7.46(s,1H), 7.31(s,1H), 4.16(s,3H), 3.41(s,2H) ), 3.01(s,1H), 2.37(s,3H), 2.30-2.18(m,2H), 1.82(d,J=10.4Hz,1H), 1.63(d,J=11.4Hz,1H), 0.80(dd,J=32.5,21.4Hz,4H).

[0145] Example 9 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine [ka] Step 1: tert-butyl7-[6-[8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octa-6-ene-4-carboxylate A solution of tert-butyl 7-(6-bromothieno[3,2-b]pyridine-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (500.0 mg, 1.19 mmol, 1.0 equivalent), [8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazin-6-yl]boronic acid (288.34 mg, 1.19 mmol, 1.0 equivalent), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (86.83 mg, 0.12 mmol, 0.1 equivalent), and potassium carbonate (492.01 mg, 3.56 mmol, 3.0 equivalent) in 1,4-dioxane (8 mL) and water (2 mL) was heated at 90°C for 10 hours under a nitrogen atmosphere. The solvent was evaporated, and the residue was purified by silica gel column chromatography (elution with 0-5% MeOH in DCM) to obtain the title compound (260.0 mg, 0.48 mmol, yield 40.6%) as a yellow solid. M+H[540.3]+,RT=1.51

[0146] Step 2: tert-butyl7-[6-[8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate To a solution of tert-butyl 7-[6-[8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octa-6-en-4-carboxylate (230.0 mg, 0.43 mmol, 1.0 equivalent) in ethyl acetate (150 mL), Pd / C (20.0 mg) was added. The resulting mixture was passed through hydrogen and stirred at 50°C under 1.0 atm for 48 hours. The mixture was filtered, and the filtrate was concentrated under vacuum to obtain the title compound (220.0 mg, 0.41 mmol, yield 89.58%) as a pale yellow solid. M+H[542.2]+,RT=1.54

[0147] Step 3: 2-(4-Azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine To a solution of tert-butyl 7-[6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (200.0 mg, 0.37 mmol, 1.0 eq) in dichloromethane (5 mL) was added HCl in dioxane (3.0 mL, 12.0 mmol, 14.39 eq), and the mixture was stirred at 25 °C for 2 h. The solid was filtered to give 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine, hydrochloride (174.46 mg, 0.37 mmol, yield 92.08%) as a pale yellow solid. M+H [442.2]+, RT = 1.00. 1 H NMR (400 MHz, DMSO) δ 10.13 (s, 1H), 9.72 (d, J = 8.8 Hz, 1H), 9.42 (s, 2H), 8.41 (s, 1H), 8.10 (t, J = 35.7 Hz, 2H), 7.58 (s, 1H), 3.55 (t, J = 11.7 Hz, 1H), 3.38 (d, J = 12.2 Hz, 1H), 3.15 - 3.05 (m, 1H), 2.51 - 2.45 (m, 4H), 2.30 (d, J = 13.1 Hz, 1H), 2.12 (d, J = 12.0 Hz, 1H), 1.69 (d, J = 13.2 Hz, 1H), 1.16 (s, 2H), 0.86 (s, 2H).

[0148] Example 10 2-[(7R)-4-Azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine

Chemical formula

[0149] Putative P1 is the white solid (7R)-7-[6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octane-4-carboxylic acid tert-butyl ester (16 mg, yield 26.17%). MS [M]+: 586.6 [α] 27.8 D =-0.28 (c: 1.0 g / 100 mL, MeOH)

[0150] The putative P2 is the white solid (7S)-7-[6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octane-4-carboxylic acid tert-butyl ester (19 mg, yield 11.2%). MS [M]+: 586.6 [α] 28.1 D = +0.24 (c: 1.0 g / 100 mL, MeOH)

[0151] Step 2a: 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine To a solution of (7R)-7-[6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octane-4-carboxylic acid tert-butyl ester (16 mg, 0.030 mmol, 1.00 equivalent) in propanol (2 mL) was added 37% aqueous HCl solution (240 mg, 200 μL, 2.44 mmol, 82.45 equivalents). The reaction mixture was heated at 70 °C for 1 hour. The solvent was evaporated to give 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine, hydrochloride. MS [M]+: 442.2 [α] 20.0 D = -1.99 (c: 1.0 g / 100 mL, MeOH)

[0152] Step 2b: 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine A solution of (7S)-7-[6-[8-(difluoromethoxy)-2-methylimidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylic acid tert-butyl ester (19 mg, 0.035 mmol, 1.000 equivalents) in propanol (2 mL) was mixed with a 37% aqueous HCl solution (240 mg, 200 μL, 2.44 mmol, 82.445 equivalents). The reaction mixture was heated at 70°C for 1 hour. The solvent was evaporated to obtain 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine hydrochloride. MS[M]+:442.2 [α] 20.2 D = +2.83 (c: 1.0g / 100mL, MeOH)

[0153] Example 12 2-(4-azaspiro[2.5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine [ka] Step 1: tert-butyl7-[6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridin-2-yl]-4-azaspiro[2.5]octa-6-ene-4-carboxylate A mixture of tert-butyl 7-(6-bromothieno[3,2-b]pyridin-2-yl)-4-azaspiro[2.5]octa-6-en-4-carboxylate (337.08 mg, 0.8 mmol, 1.0 equivalent), [2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazin-6-yl]boronic acid (208.78 mg, 0.8 mmol, 1.0 equivalent), XPhos-Pd g3 (67.72 mg, 0.08 mmol, 0.1 equivalent), and potassium carbonate (331.69 mg, 2.4 mmol, 3.0 equivalents) in 1,4-dioxane (8 mL) and water (2 mL) was heated at 90°C for 10 hours under a nitrogen atmosphere. The organic layer was concentrated under vacuum, and the residue was purified by silica gel column chromatography (elution with 0-60% Â in PE) to obtain the title compound (30.0 mg, 0.05 mmol, yield 16.92%) as a grayish-white solid. M+H[557.8]+, RT=1.56

[0154] Step 2: tert-butyl7-[6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate To a solution of tert-butyl 7-[6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octa-6-ene-4-carboxylate (30.0 mg, 0.05 mmol, 1.0 equivalent) in ethyl acetate (100 mL), Pd / C (20.0 mg, 10%) was added. The resulting mixture was passed through hydrogen and stirred at 50°C under 1.0 atm for 24 hours. The mixture was filtered, and the filtrate was concentrated under vacuum to obtain the title compound (28.0 mg, 0.05 mmol, yield 79.98%) as a white solid. M+H[560.3]+, RT=1.54

[0155] Step 3: 2-(4-azaspiro[2,5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine To a solution of tert-butyl 7-[6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazin-6-yl]thieno[3,2-b]pyridine-2-yl]-4-azaspiro[2.5]octane-4-carboxylate (23.0 mg, 0.04 mmol, 1.0 equivalent) in DCM (3 mL), a solution of 4N hydrogen chloride in 1,4-dioxane (3.0 mL, 12.0 mmol, 291.97 equivalents) was added, and the mixture was stirred at 25°C for 2 hours. The solvent was evaporated, and the residue was purified by preparative HPLC (Gemini-C18 150 × 21.2 mm, 5 μm ACN-H2O (0.1% TFA)) to obtain the title compound (7.88 mg, 0.01 mmol, yield 32.49%) as a white solid. M+H[460.2]+,RT=1.05 1 H NMR (400MHz, DMSO) δ9.29(s,1H), 9.12(s,1H), 8.32(s,1H), 7.93(s,1H), 7.51(s,1H), 3.49(s ,3H), 2.46(s,3H), 2.35(d,J=13.8Hz,2H), 1.84(dd,J=72.3,14.0Hz,2H), 1.07-0.86(m,4H).

[0156] Uniform time-resolved fluorescence for HTT reduction The HTRF assay was adapted from the assay by Weiss et al. (Analytical Biochemistry Volume 395, Issue 1, 1 December 2009, Pages 8-15 and Analytical Biochemistry Volume 410, 2011, Pages 304-306) to cells of the GENEAe020-A cell line (https: / / hpscreg.eu / cell-line / GENEAe020-A).

[0157] We tested compounds on the effect of mutant HTT levels in Huntington's disease patient human cells (GENEAe020-A cell line) using homogeneous time-resolved fluorescence (HTRF) against mutant HTT protein (mHTT). The GENEAe020-A cell line was derived from Genea Biocells from human blastocysts of HD donors. After assessing viability, cells were seeded in 384-well collagen-coated plates in growth medium. Once cells adhered, the medium was removed, and the test compounds dissolved in DMSO were diluted in buffer and added to the adherent cells. Controls included cell-free experiments, DMSO without the compounds, and Hsp90 inhibitor controls. Cells were incubated with the compounds and controls for 48 hours. Subsequently, the cells were lysed and transferred to assay plates containing an HTRF-labeled monoclonal antibody that recognizes a specific region of the HTT protein, developed by Paul Patterson (Ko et al., Brain Research Bulletin, Volume 56, Numbers 3 and 4, 2001, Pages 319-329). The terbium-labeled "donor" antibody (2B7) binds to the N-terminus of the HTT protein, while the Alexa488-labeled "acceptor" antibody (MW1) is specific to the polyglutamine region of the protein. Binding of the acceptor-labeled antibody is more efficient for the extended polyglutamine repeat of the mutant HTT protein, which is translated into a signal boost that allows for specific measurement of mutant HTT protein levels. The HTRF donor detection reagent and the HTRF acceptor detection reagent are incubated with cell lysates, and the ratio between the signals of the two phosphors indicates the relative amount of mHTT.

[0158] The assay results are shown in Table 9 below. Table 9 shows the EC ratio to the reduction in mHTT obtained for a specific example of the present invention, as measured by the HTRF assay. 50 The (maximum half dose effective concentration) value is provided (the data shown below is the average of three replicates).

[0159] QPCR quantification of HTT and FOXM1 splice variants in Hs68 fibroblasts Hs68 fibroblasts (cell line 89051701) obtained from the European Collection of Authenticated Cell Culture were seeded at a density of 60,000 cells / cm2 (100 μl cell suspension / well) in 96-well plates in DMEM + 4.5 g glucose (Gibco#31966) supplemented with 10% FBS (Thermo Fisher Scientific#A3160501), and placed in an incubator at 37 °C with 10% CO2 and 85% humidity.

[0160] The cells were treated immediately after seeding. Compounds were prepared by serial dilution in a 1:3 dilution starting from a final highest concentration of 1 μM to obtain an 11-point concentration series. Control wells were treated with 0.1% DMSO. 100 μl of the diluted compound was added to the cell culture plates. After a 24-hour treatment period, the cells were washed with cold PBS and then the experiment was terminated by adding 50 μL of lysis solution (Cells-to-CT (trademark) bulk lysis reagent, Thermo Fisher Scientific#4391851C) and incubating for 5 minutes. The reaction was stopped with 5 μl of stop solution provided in the kit.

[0161] The RT-qPCR reaction was processed on a Roche LightCycler LC480 real-time PCR system using 2 μl of cell lysate in a 10 μl mixture containing 5 μl of Ag-Path-ID One-Step RT-PCR (Applied Biosystems, AM1005) buffer, 0.4 μl of AmpliTaq Gold DNA Polymerase supplied in the kit, 0.1 μM of each forward primer and reverse primer listed in Table 8, and 0.04 μM of probe (FAM for target, HEX for housekeeping gene). The temperature cycle consisted of an incubation at 48 °C for 15 minutes for the reverse transcription step, followed by inactivation of the reverse transcriptase at 95 °C for 10 minutes, 45 cycles of amplification (15 seconds at 95 °C, 1 minute at 60 °C), and a cooling step at 4 °C for 15 seconds.

[0162] The primer and probe sequences in Table 8 were used for the measurement of splice isoforms using the Taqman assay. EIF4G1 was used as a housekeeping gene in all QPCR assays. Taqman PCR data were acquired using a Light Cycler 480 (Roche Diagnostics), and Cp values ​​in a txt file with two channels, 465–510 [FAM] and 533–580 [HEX], were used for analysis.

[0163] The Cp values ​​for biological and technical replication of the test gene (Cp1) and the housekeeping gene (Cp2) were calculated using automated thresholding in Lightcycler software (Lightcycler 480 Software release 1.5.1.62 SP3). Relative transcription levels were calculated as follows: Cp1-test gene cycle threshold Cp2-housekeeping gene cycle threshold ΔCp = Cp2 - Cp1 ΔΔCp = ΔCp(processing condition) - ΔCp(control) Relative transcription level = 2(-ΔΔCp)

[0164] The concentration-response curve was generated using the concentration of the test item as (X) and the relative transcription level as the response (Y). This curve was fitted using the 4-parameter logistic equation in XLfit or GraphPad Prism, as follows. y = (A + (BA) / (1 + (C / x)^D))

[0165] A and B are the lower and upper plateaus of the curve, C is EC50 (or IC50), and D is the gradient coefficient (hill gradient).

[0166] The assay results are shown in Table 9 below. EC50 is the concentration of the test substance that elicits half of the maximum response. The Hill slope represents the steepness of the curve. The maximum response on the Y-axis is defined as Top, and the minimum response as Bottom. For HTT exon 50-NF, the top was set to 1 and the bottom to 0. For HTT exon 50 LF and FOXM1ex9i, the bottom was set to 0 and the top was limited to the maximum observed value of that experiment. [Table 8] [Table 9]

Claims

1. Compound of formula (I) 【Chemistry 1】 (In the formula, R １ and R ２ These are independently selected from hydrogen and alkyl, or R １ and R ２ These, together with the carbon atoms to which they are bonded, form a cycloalkyl group. R ３ is hydrogen, halogen, alkyl, alkoxy, haloalkyl or haloalkoxy, R ４ is hydrogen, alkyl, or halogen, A １ (is -N- or -CH-) or a pharmaceutically acceptable salt thereof.

2. R １ and R ２ are both hydrogen, or R １ and R ２ together with the carbon atom to which they are attached form a cycloalkyl, a compound according to claim 1.

3. R １ and R ２ Both are hydrogen, or R １ and R ２ The compound according to claim 1 or 2, wherein they combine with the carbon atoms to which they are bonded to form a cyclopropyl group.

4. R ３ The compound according to any one of claims 1 to 3, wherein the compound is hydrogen, methyl, methoxy, fluoro, trifluoromethyl, difluoromethoxy, or trifluoromethoxy.

5. R ４ The compound according to any one of claims 1 to 4, wherein the alkyl group is alkyl.

6. R ４ The compound according to any one of claims 1 to 5, wherein is methyl.

7. A １ The compound according to any one of claims 1 to 6, wherein is -N-.

8. A １ The compound according to any one of claims 1 to 6, wherein is -CH-.

9. 6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-[2-methyl-8-(trifluoromethyl)imidazo[1,2-b]pyridazin-6-yl]-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-(4-azaspiro[2.5]octan-7-yl)-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 6-(2,8-dimethylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(2-methylimidazo[1,2-b]pyridazine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 6-(8-fluoro-2-methylimidazo[1,2-a]pyridine-6-yl)-2-(4-piperidyl)thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-(8-methoxy-2-methylimidazo[1,2-b]pyridazine-6-yl)thieno[3,2-b]pyridine, 2-(4-azaspiro[2.5]octan-7-yl)-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7R)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, 2-[(7S)-4-azaspiro[2.5]octan-7-yl]-6-[8-(difluoromethoxy)-2-methyl-imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine, and 2-(4-azaspiro[2.5]octan-7-yl)-6-[2-methyl-8-(trifluoromethoxy)imidazo[1,2-b]pyridazine-6-yl]thieno[3,2-b]pyridine A compound of formula (I) according to any one of claims 1 to 8, selected from: or a pharmaceutically acceptable salt thereof.

10. The following steps: (b) Compound of formula (B1) in a suitable solvent, in the presence of a base and a suitable palladium catalyst 【Chemistry 2】 The compound of formula (B2) 【Transformation 3】 Reacting with (wherein PG is a suitable protecting group, -B(OR) ２ In this, each R is independently selected from hydrogen and alkyl, or -B(OR) ２ The compound of formula (B3) is a suitable dioxavoranyl. 【Chemistry 4】 The process of obtaining (b) Hydrogenating the compound of formula (B3) in a suitable solvent, in the presence of hydrogen and a suitable catalyst, to obtain the compound of formula (B4) 【Transformation 5】 The process of obtaining (c) React the compound of formula (B4) in a suitable solvent under suitable conditions to obtain the compound of formula (I). 【Transformation 6】 process to obtain A process for preparing a compound according to any one of claims 1 to 9, comprising at least one of the following, wherein PF is a protecting group and A1, R1, R2 and R3 are according to any one of the preceding claims.

11. The compound according to any one of claims 1 to 9, as produced according to the process described in claim 10.

12. A compound according to any one of claims 1 to 9, for use as a therapeutically active substance.

13. A pharmaceutical composition comprising a compound according to any one of claims 1 to 9 and a therapeutically inert carrier.

14. A compound according to any one of claims 1 to 9, for use in the treatment or prevention of neurodegenerative diseases, particularly Huntington's disease.

15. Use of the compound according to any one of claims 1 to 9 for the treatment or prevention of neurodegenerative diseases, particularly Huntington's disease.

16. Use of the compound according to any one of claims 1 to 9 for preparing a medicine for the treatment or prevention of neurodegenerative diseases, particularly Huntington's disease.

17. A method for treating or preventing a neurodegenerative disease, particularly Huntington's disease, comprising administering an effective amount of a compound according to any one of claims 1 to 9 to a patient in need thereof.

18. The invention as previously described herein.

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