Retinoids for RAR-activated synthesis

Abstract

The present invention relates to a retinoid for RAR activated synthesis. The present invention relates to the use of a compound of formula I in the manufacture of a medicament for the treatment of a condition or disease ameliorated by activation of the retinoic acid receptor (RAR): wherein A1-A7 and R1 to R5 are defined herein. The invention also relates to pharmaceutical compositions comprising such compounds. Aspects of the invention relate to novel compounds of formula I, wherein A1-A7 and R1 to R5 are defined herein. # imgabs0 #

Description

[0001] This application is a divisional application of the application with the filing date of March 11, 2020, application number 202080018638.1, and invention title "Synthetic Retinoids for RAR Activation".

[0002] The present invention relates to compounds of formula I:

[0003]

[0004] wherein A 1 -A 7 and R 1 to R 5 are defined herein, and the compounds are useful for treating conditions or diseases alleviated by activating retinoic acid receptor (RAR). The present invention also relates to pharmaceutical compounds comprising such compounds, and related methods of treatment. In aspects, the present invention relates to methods of screening compounds for therapeutic potential against a condition or disease alleviated by activating retinoic acid receptor (RAR). In aspects, the present invention relates to novel compounds of formula I, wherein at least one of A 1 to A 3 is N, or A 4 is CR 12 or A 5 is CR 13 and at least one of them, wherein R 12 / R 13 is a halogen.

[0005] More particularly, the present invention relates to the use of compounds of formula I in the treatment of conditions and / or diseases alleviated by activating RAR, such as neurological conditions, including neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease and Parkinson's disease, and conditions such as spinal cord injury.

[0006] Retinoids are a family of natural or synthetic compounds that are analogs of vitamin A and its derivatives. Retinoids are essential for many cellular activities and participate as signaling molecules in controlling important biological pathways from embryogenesis to adult homeostasis, and in aspects of stem cell development, such as proliferation, differentiation and apoptosis. All-trans retinoic acid (ATRA) is the most abundant endogenous retinoid and has been used as a model compound for studying retinoids.

[0007] Retinoids act on a group of nuclear receptors called retinoic acid receptors (RARs); retinoic acid receptors (RARs) are inducible ligand-activated transcription factors that regulate multiple physiological mechanisms at the genomic level. Thus, synthetic retinoids have been investigated as potential therapeutic agents for a range of diseases and conditions mediated or potentially mediated by RARs. However, to date, known compounds have suffered from drawbacks such as low efficacy or potency, or have exhibited poor physical properties, including low water solubility.

[0008] Neurological conditions are diseases of the central and peripheral nervous systems, namely the brain, spinal cord, cranial nerves, peripheral nerves, nerve roots, autonomic nervous system, neuromuscular junction, and muscles. Neurological conditions include sudden onset conditions such as those caused by spinal cord injury or stroke; intermittent conditions such as epilepsy; neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease, and Parkinson's disease; and stable conditions such as cerebral palsy. Overall, the group of neurological conditions tends to be chronic; many are life-threatening, and all have a significant negative impact on quality of life. It is estimated that hundreds of millions of people worldwide are affected by neurological disorders (World Health Organisation, May 2016).

[0009] Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a debilitating neurological condition characterized by the progressive loss of motor neurons and the resulting paralysis. In Europe, it is estimated that there are 1.7 to 2.3 cases of ALS per 100,000 population per year [Logroscino et al., "Incidence of amyotrophic lateral sclerosis in Europe", J Neurol Neurosurg Psychiatry. (2009); 81(4):385-90], and it is estimated that approximately 50% of patients die within 30 months of symptom onset [Kiernan et al., "Amyotrophic lateral sclerosis." The lancet; Volume 377 (9769); (2011):942-955]. However, despite the devastating nature of the disease, there is currently no cure; the only drug approved for the treatment of ALS in the UK has been shown to extend patients' lives by an average of 2 to 3 months [Miller et al., "Riluzole for amyotrophic lateral sclerosis (ALS) / motor neuron disease (MND).", Cochrane Database of Systematic Reviews (2012), Issue 3. CD001447].

[0010] ALS can be sporadic and familial, with causative mutations described in multiple genes such as C9ORF72 and SOD1. The underlying cause of ALS is the death of motor neurons that drive muscle movement, but to date, the exact mechanism by which this occurs is unknown. However, several mechanisms have been implicated, including (i) excitotoxicity; the toxic effects of neurotransmitters that cause neurons to fire excessively; (ii) autophagy failure; the loss of the cell's detoxification system that removes the accumulation of insoluble molecules in the cell; (iii) neuroinflammation; the misdirected attack of immune cells of the nervous system on motor neurons; and (iv) axonal disorganisation; the loss of the interconnecting fibres between neurons that are necessary for neuronal communication. Therefore, any therapeutic agent for the treatment of ALS would ideally exhibit multiple polypharmocological properties.

[0011] Accordingly, there is an urgent and unmet need for new therapeutic agents for treating neurological conditions such as neurodegenerative disorders (including ALS and Alzheimer's disease). Compounds that exhibit good physical properties such as good water solubility would be particularly useful.

[0012] While therapeutic agents that can cure or prevent ALS, Alzheimer's disease, or related disorders represent the ultimate goal of most drug research programs, more realistically, therapeutic agents that can delay the onset of the disease, slow or stop the progression of the disease would represent significant progress. Methods for screening compounds for potential therapeutic use would also be highly beneficial. Summary of the Invention

[0014] Accordingly, the present invention relates to compounds for treating conditions or diseases alleviated by activating retinoic acid receptors. In aspects, this includes genomic activation. In aspects of the present invention, the compounds activate both genomic and non-genomic pathways.

[0015] In aspects, the present invention relates to pharmaceutical compositions comprising such compounds, and the use of such compounds and compositions in treating conditions or diseases alleviated by activating retinoic acid receptors.

[0016] Conditions or diseases alleviated by activating retinoic acid receptors include RAR-mediated conditions such as neurodegenerative disorders, and conditions alleviated by activating RAR such as stroke, traumatic brain injury, epilepsy, spinal cord injury, etc.

[0017] In aspects, the present invention relates to methods for screening compounds for therapeutic potential for treating conditions or diseases alleviated by activating retinoic acid receptors.

[0018] Aspects of the present invention relate to the novel compounds themselves.

[0019] Additional aspects and embodiments of the present invention are defined herein and described in more detail below.

[0020] According to a first aspect of the present invention, there is provided a compound of formula I:

[0021]

[0022] Wherein:

[0023] A 1 is N or CR 6 ;

[0024] A 2 is N or CR 7 ;

[0025] A 3 is N or CR 8 ;

[0026] R 6 and R 8 each independently is hydrogen, C1-C 10 alkyl, F, Br or Cl;

[0027] R 7 independently is hydrogen, C1-C 10 alkyl, F, Br, Cl or -OCR 9 wherein R 9 is H or C1-C6 alkyl;

[0028] R 1 to R 4 each independently is C1-C 10 alkyl, or R 1 and R 2 and / or R 3 and R 4 are linked to form a 3-membered ring;

[0029] A 4 is N or CR 12 ;

[0030] A 5 is N or CR 13 ;

[0031] A 6 is N or CR 14 ;

[0032] A 7 is N or CR 15 ;

[0033] each R 12 to R 15 independently is H, halogen or C1-C 10 haloalkyl; and

[0034] R 5 is -C(=O)R 16 or -C(=O)OR 16 wherein R 16 is H or C 1-10 alkyl;

[0035] provided that at least one of A 1 to A 7 is N, or at least one of R 12 to R 15 is F, Cl or Br;

[0036] and its isomers;

[0037] in free form or in salt form;

[0038] for treating a condition or disease alleviated by activating a retinoic acid receptor (RAR).

[0039] In the compounds of formula I, A 1 to A 7 at least one of which is N, or R 12 to R 15 at least one of which is F, Cl or Br.

[0040] As used herein, the term "alkyl" refers to a fully saturated, branched, unbranched or cyclic hydrocarbon moiety, i.e., a primary, secondary or tertiary alkyl group, or, where appropriate, a cycloalkyl group or an alkyl group substituted with a cycloalkyl group. Unless otherwise indicated, alkyl groups contain from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, or more preferably from 1 to 4 carbon atoms. Representative examples of alkyl groups include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, n-nonyl and n-decyl.

[0041] As used herein, the term "halogen" or "halo" means fluorine, chlorine, bromine or iodine.

[0042] As used herein, the term "haloalkyl" refers to an alkyl group in which one or more hydrogen atoms are replaced by halogen atoms.

[0043] Conditions or diseases alleviated by activating a retinoic acid receptor include RAR-mediated conditions such as neurodegenerative disorders, and conditions alleviated by activating RAR such as stroke, traumatic brain injury, epilepsy, spinal cord injury, etc.

[0044] RAR-mediated conditions include neurodegenerative disorders, which include amyotrophic lateral sclerosis (ALS), neuromuscular diseases, Parkinson's disease, multiple sclerosis (MS), Alzheimer's disease, early Alzheimer's disease, middle Alzheimer's disease, late Alzheimer's disease, cognitive disorder, memory impairment, memory deficit, senile dementia, vascular dementia, cognitive impairment and mild cognitive impairment.

[0045] Accordingly, the conditions or diseases alleviated by activating RAR can be selected from amyotrophic lateral sclerosis (ALS), neuromuscular diseases, Parkinson's disease, multiple sclerosis (MS), Alzheimer's disease, early Alzheimer's disease, middle Alzheimer's disease, late Alzheimer's disease, cognitive impairment, memory impairment, memory deficit, senile dementia, vascular dementia, cognitive impairment, mild cognitive impairment, stroke, traumatic brain injury, epilepsy, and spinal cord injury.

[0046] The condition can be a neurological condition. In an embodiment, the neurological condition can be a neurodegenerative condition, such as ALS, Parkinson's disease, or Alzheimer's disease.

[0047] In an embodiment, R 5 is -COOH.

[0048] In an embodiment, at least one of A 1 to A 3 is N, or A 4 is CR 12 or A 5 is CR 13 wherein at least one of R 12 / R 13 is a halogen. R 12 / R 13 is preferably F.

[0049] In an embodiment, at least one of A 1 to A 3 is N. In an embodiment, both A 1 and A 3 are N.

[0050] In an embodiment, A 2 is CR 7 wherein R 7 is H.

[0051] In an embodiment, at least one of A 4 , A 5 or A 6 is CF.

[0052] In this embodiment, A 4 can be CF. Alternatively, A 5 can be CF.

[0053] In an embodiment, A 5 and A 6 are CF.

[0054] In an embodiment, A 4 is CCl.

[0055] In an embodiment, A 1 and A 3 are both N, and A 2 is CR 7 , where R 7 is H, as represented by Formula IA:

[0056]

[0057] Preferably, in Formula IA, R 5 is -COOH.

[0058] Optionally, in an embodiment, in Formula I, at least one of A 4 to A 7 is N.

[0059] In an embodiment, in Formula I, A 4 is N.

[0060] In an embodiment, in Formula I, A 4 or A 5 is CF.

[0061] Generally, the compounds of Formula I have a hydrophobic region, a linker region (-C≡C-), and a polar region, as shown below:

[0062]

[0063] The inventors have advantageously found that compounds of Formula I in which one nitrogen atom or preferably two nitrogen atoms are incorporated into the conjugated ring of the hydrophobic region; or in which a nitrogen atom is incorporated into the conjugated ring of the polar region and / or the conjugated ring of the polar region is halogenated (or preferably fluorinated) can be surprisingly beneficial in the treatment of diseases or conditions alleviated by activation of RAR.

[0064] Exemplary compounds of Formula I that may be mentioned include compounds selected from the group consisting of:

[0065]

[0066] In a particular embodiment, the compounds of Formula I may be selected from:

[0067]

[0068] In an embodiment, the compounds of Formula I may be selected from:

[0069]

[0070] In an embodiment, the compounds of Formula I may be selected from:

[0071]

[0072] In another aspect of the invention, there is provided the use of a compound of formula I as defined herein in the manufacture of a medicament for the treatment of a disease or condition alleviated by activation of RAR. In an embodiment, the medicament comprises a compound of formula I.

[0073] In another aspect of the invention, there is provided a method of treating a patient suffering from a disease or condition alleviated by activation of RAR, the method comprising administering to the patient a therapeutically effective amount of a compound of formula I, wherein the compound of formula I is as defined herein.

[0074] In another aspect of the invention, there is provided a pharmaceutical composition comprising a compound of formula I as defined herein, optionally in combination with one or more pharmaceutically acceptable excipients, diluents or carriers, for the treatment of a disease or condition alleviated by activation of RAR. The composition may optionally comprise one or more additional therapeutic agents.

[0075] The term "therapeutically effective" amount or "effective amount" refers to the amount of a compound or composition of the invention effective to produce the desired therapeutic, ameliorating, inhibitory or prophylactic effect.

[0076] The term "pharmaceutical composition" refers to a composition suitable for administration to a patient. Thus, the term "pharmaceutical composition" refers to a composition comprising a compound of the invention or a mixture thereof, or a salt, solvate, prodrug, isomer or tautomer thereof, optionally in combination with one or more pharmaceutically acceptable excipients, carriers or diluents. The term "pharmaceutical composition" is also intended to cover the bulk composition (i.e., in a form not yet formed into separate dosage units) and separate dosage units. Such separate dosage units include tablets, pills, cachets, ampoules, etc.

[0077] Those skilled in the art will recognize those situations in which the compounds of the invention can be converted into prodrugs and / or solvates. The term "prodrug" refers to a compound (e.g., a drug precursor) that is converted in vivo to produce a compound of the invention or a pharmaceutically acceptable salt, hydrate or solvate of the compound. The conversion can occur by a variety of mechanisms (e.g., by metabolic processes or chemical processes), such as, for example, by hydrolysis in the blood.

[0078] The compounds of the present invention may be unsolvated or may be solvated with pharmaceutically acceptable solvents such as water, ethanol and analogous solvents. For example, it should be understood that solvates may be capable of being isolated, e.g., when one or more solvent molecules are incorporated into the lattice of the crystalline solid. "Solvate" includes both solution-phase and isolable solvates. Suitable solvates include, but are not limited to, ethanolates, methanolates, hydrates, and the like.

[0079] Unless otherwise indicated, compounds used in the present invention include their salts, and references to the compounds of the present invention are intended to include references to their salts. Suitable salts include, for example, acid addition salts formed with inorganic acids and / or organic acids, basic salts formed with inorganic bases and / or organic bases, and zwitterions ("inner salts") that can be formed and are included in the term "salt" as used herein. Pharmaceutically acceptable (i.e., non-toxic, physiologically acceptable) salts are preferred, although other salts may be useful in certain circumstances. Exemplary acid addition salts that may be useful include acetate, ascorbate, benzoate, benzenesulfonate, bisulfate, borate, butyrate, citrate, camphorate, camphorsulfonate, fumarate, hydrochloride, hydrobromide, hydroiodide, lactate, maleate, mesylate, naphthalenesulfonate, nitrate, oxalate, phosphate, propionate, salicylate, succinate, sulfate, tartrate, thiocyanate, toluenesulfonate (also known as tosylate), and the like acid addition salts. Exemplary basic salts that may be useful include ammonium salts, alkali metal salts such as sodium, lithium and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, salts with organic bases (e.g., organic amines) such as dicyclohexylamine, tert-butylamine and salts with amino acids such as arginine, lysine, and the like basic salts. Basic nitrogen-containing groups may be quaternized with agents such as lower alkyl halides (e.g., chlorides, bromides and iodides of methyl, ethyl and butyl), dialkyl sulfates (e.g., sulfates of dimethyl, diethyl and dibutyl), long chain halides (e.g., chlorides, bromides and iodides of decyl, lauryl and stearyl), arylalkyl halides (e.g., bromides of benzyl and phenethyl), and others.

[0080] Compounds used in the present invention include their pharmaceutically acceptable esters and may include carboxylic acid esters obtained by esterification of a hydroxy group, wherein the non-carbonyl moiety of the carboxylic acid moiety of the ester group is selected from (1) straight or branched chain alkyl (e.g., acetyl, n-propyl, tert-butyl or n-butyl), alkoxyalkyl (e.g., methoxymethyl), aralkyl (e.g., benzyl), aryloxyalkyl (e.g., phenoxymethyl), aryl (e.g., optionally substituted with, for example, halogen, C 1-4 alkyl or C 1-4(1) an alkoxy- or amino-substituted phenyl); (2) a sulfonate ester, such as an alkylsulfonyl or aralkylsulfonyl (e.g., mesyl); (3) an amino acid ester (e.g., L-valyl or L-isoleucyl); (4) a phosphonate ester; and (5) a monophosphate, diphosphate or triphosphate ester.

[0081] Polymorphic forms of the compounds of the invention, as well as polymorphic forms of salts, solvates, esters and prodrugs of the compounds of the invention, are intended to be included in the invention.

[0082] A suitable dose for administering the compounds of the invention to a patient can be determined by a person skilled in the art, such as a treating physician, pharmacist or other skilled person, and can vary depending on factors such as the patient's weight, health, age, frequency of administration, mode of administration, the presence of any other active ingredient, and the conditions under which the compound is administered.

[0083] Examples of excipients, diluents and carriers include buffering agents, and fillers and extenders such as starches, celluloses, sugars, mannitols and silicic derivatives. Binding agents can also be included. Adjuvants can also be included.

[0084] Optionally, the compounds of formula I can be administered in combination with one or more additional therapeutic agents. When used in combination with one or more additional therapeutic agents, the compounds of the invention can be administered together or sequentially.

[0085] The compositions can be administered by a variety of routes, including oral, parenteral (including subcutaneous, intravenous, intramuscular and intraperitoneal), rectal, dermal, transdermal, intrathoracic, intranasal, mucosal, intraocular and intranasal routes.

[0086] Suitable dosage forms will be recognized by those skilled in the art and particularly include tablets, capsules, solutions, suspensions, powders, aerosols, ampoules, pre-filled syringes, small volume infusion containers or multi-dose containers, creams, milks, gels, dispersions, microemulsions, lotions, impregnated pads, ointments, eye drops, nose drops, lozenges, etc.

[0087] Aspects of the invention relate to compounds of formula I as described above, wherein A 1 to A 3 at least one of which is N, or A 4 is CR 12 or A 5 is CR 13 at least one of which, wherein R 12 / R13 is a halogen. Such aspects relate to the novel compounds themselves.

[0088] R 12 / R 13 is preferably F.

[0089] In an embodiment, at least one of A 1 to A 3 is N.

[0090] In an embodiment, both A 1 and A 3 are N.

[0091] In an embodiment, the novel compound is selected from:

[0092]

[0093] In an aspect of the present invention, there is provided a method for screening a compound for therapeutic potential against a therapeutic condition or disease, the condition or disease being alleviated by activating a retinoic acid receptor, the method comprising:

[0094] - performing a determination of the potency (E 最大 ) of the compound in activating RAR as an indicator of genomic activity;

[0095] - performing a determination of the potency (E 最大 ) of the compound as an indicator of non-genomic activity;

[0096] For each determination, comparing E 最大 with a baseline value; and,

[0097] - selecting those compounds having an E 最大 higher than the baseline value in both determinations for further study.

[0098] Since the discovery of RAR as a member of the nuclear receptor family of transcriptional regulators (Petkovich M et al. “A human retinoic acid receptor which belongs to the family of nuclear receptors”; Nature (1987): 330, pp. 444 - 450), the emphasis on retinoid function has been on their control of gene expression. On this basis, synthetic retinoids have been generated and their genomic activation properties have been studied.

[0099] Surprisingly, however, the inventors have determined that the genomic and non-genomic mechanisms of retinoic acid (RA) are regulated independently of the involvement of ligand-dependent RAR. "Dual-efficacy", i.e., activity in both non-genomic and genomic assays, has been found to be closely associated with the promotion of neurite outgrowth and increased cell number and viability, indicating that these dual-acting compounds are important as potential therapeutic agents.

[0100] In an embodiment, determining the E of a compound 最大 The assay as an indicator of non-genomic activity is a kinase phosphorylation assay.

[0101] In an embodiment, the kinase phosphorylation assay is an ERK1 / 2 phosphorylation assay.

[0102] In an embodiment, the baseline value as an indicator of genomic activity is the E of 170.1 最大 .

[0103] In an embodiment, the baseline value as an indicator of non-genomic activity is the E of 48.55 最大 .

[0104] In an embodiment, one or both of the baseline values can be determined using a reference compound such as ATRA. Examples:

[0105] The present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0106] Figure 1 illustrates the synthesis of a coupling partner;

[0107] Figure 2 Illustrates the synthesis of exemplary retinoid compounds DC526, DC528, DC641 and DC645;

[0108] Figure 3 Illustrates the genomic activity of a retinoid, as indicated by using an X-Gal assay;

[0109] Figure 4 Illustrates the non-genomic activity of a retinoid, as indicated by its ability to induce phosphorylation of ERK1 / 2;

[0110] Figure 5 Illustrates the average neurite length of differentiated SH-SY5Y cells after treatment with a retinoid;

[0111] Figure 6 Shows the genomic activity induced by a retinoid [(transcriptional activity: E 最大(Potency)] and non-genomic activity [ERK1 / 2 activity: E 最大 (Potency)] between the ability of both and the induction of neurite outgrowth (fold increase at 10 μM), where the highlighted retinoids exhibit both activities;

[0112] Figure 7 Shows data on the transcriptional regulation of Alzheimer's disease-related genes in primary neuron / glial cultures from rats treated with retinoids;

[0113] Figure 8 compares the activities of the exemplary retinoid DC645 with those of ATRA and EC23. Figure 8(a) compares the genomic activities of the retinoids by means of an X-Gal assay; Figure 8(b) compares their non-genomic activities by measuring the ability of the retinoids to induce ERK 1 / 2 phosphorylation; Figure 8(c) compares the ability of the compounds to induce neurite outgrowth in SH-SY5Y cells; and Figure 8(d) shows the regulation of Alzheimer's disease-related genes by the retinoid compounds.

[0114] Example 1: Synthesis of exemplary compounds of formula I:

[0115] 1.1 Synthesis of coupling partners

[0116] 1.1.1 Synthesis of 6-iodo-1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene, 1

[0117] The synthesis of 6-iodo-1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene (1) is illustrated in Figure 1(a). 1,1,4,4-Tetramethyl-1,2,3,4-tetrahydronaphthalene (11.46 g, 60.9 mmol), I2 (7.77 g, 30.6 mmol), and H5IO6 (3.49 g, 15.3 mmol) were added to a mixture of glacial acetic acid (gl.ethanoic acid) / acetic acid (AcOH) (250 mL), H2O (25 mL), and H2SO4 (13 mL), and the resulting solution was stirred at 70 °C for 6 hours. The solution was cooled and extracted with ethyl ethanoate / ethyl acetate (EtOAc). The organic matter was washed with saturated Na2S2O3, H2O, and brine, dried (MgSO4), and evaporated to give a crude orange oil (17 g). It was purified by dry column vacuum chromatography (eluted with heptane) to give compound 1 (16.3 g, 85%) as a white solid: 11H NMR (700 MHz, CDCl3) δ 1.25 (s, 6H), 1.26 (s, 6H), 1.66 (s, 4H), 7.04 (d, J = 8.4 Hz, 1H), 7.43 (dd, J = 8.4, 1.9 Hz, 1H), 7.60 (d, J = 1.9 Hz, 1H); 13C NMR (176 MHz, CDCl3) δ 31.9, 32.0, 34.4, 34.6, 35.0, 35.1, 91.3, 128.9, 134.8, 135.8, 144.8, 147.9; All other data are consistent with the literature (V.B. Christie et al., Org. Biomol. Chem., 2008, 6, 3497 - 3507).

[0118] 1.1.2 Synthesis of 6-ethynyl-1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene, 3

[0119] The synthesis of 6-ethynyl-1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene (3) is illustrated in Figure 1(b). Triethylamine (Et3N) (150 mL) was degassed by bubbling N2 through it for 1 h. Then, compound 1 (10.0 g, 31.8 mmol), Pd(PPh3)2Cl2 (0.223 g, 0.32 mmol), CuI (0.061 g, 0.32 mmol), and trimethylsilylacetylene (5.29 mL, 38.2 mmol) were added under N2 and the resulting slurry was stirred at RT for 20 h. The mixture was diluted with heptane and passed through Celite / SiO2 (eluted with heptane), and the resulting solution was evaporated to give a crude brown oil (10.36 g). It was purified by SiO2 chromatography (100% heptane) to give compound 2 (9.99 g, >100%) as a yellow oil. Compound 2 (9.99 g, 35.1 mmol) was dissolved in methanol (MeOH) / methyl tert-butyl ether (MTBE) (1:1, 160 mL). Then, a solution of sodium hydroxide (NaOH) (0.96 g, 24.0 mmol) in H2O (15 mL) was added and the resulting solution was stirred at RT for 16 h. The solution was diluted with MTBE, washed with H2O and brine, dried (MgSO4) and evaporated to give a crude yellow oil (6.6 g). It was purified by SiO2 chromatography (100% heptane) to give compound 3 (6.06 g, 90% over two steps) as a colorless oil that slowly solidified: All data are consistent with the literature (V.B. Christie et al., Org. Biomol. Chem., 2008, 6, 3497 - 3507).

[0120] 1.1.3 Synthesis of 4-bromo-3-fluorobenzoate, 4

[0121] The synthesis of 4-bromo-3-fluorobenzoate (4) is illustrated in Figure 1(c). 4-Bromo-2-fluorobenzoic acid (25.0 g, 114.2 mmol) was suspended in MeOH (250 mL), then concentrated H2SO4 (4 mL) was added, and the resulting solution was stirred under reflux overnight. Then the clear solution was cooled, and H2O (100 mL) was added, after which a white precipitate formed. It was filtered, washed with H2O and dried to give a crude white solid. It was recrystallized from heptane to give compound 4 (21.34 g, 80%) as a colorless crystalline solid: 1 H NMR (600 MHz, CDCl3) δ 3.91 (s, 3H), 7.31 - 7.36 (m, 2H), 7.80 (t, J = 8.0 Hz, 1H); 13 C NMR (151 MHz, CDCl3) δ 52.4, 117.6 (d, J = 9.9 Hz), 120.6 (d, J = 25.6 Hz), 127.5 (d, J = 3.9 Hz), 127.9 (d, J = 9.6 Hz), 133.1, 161.56 (d, J = 264.9 Hz), 164.1 (d, J = 3.9 Hz); 19 F NMR (376 MHz, CDCl3) δ -106.6; IR (ATR) v 最大 / cm -1 3104w, 3086w, 2961w, 1712s, 1599s, 1571m, 1403m, 1215s, 882s; MS (ASAP): m / z = 233.0 [M + H] + ; HRMS (ASAP) calculated for C8H7O2BrF [M + H] + : 232.9613, found: 232.9621 (Zimmerman et al., J. Med. Chem. 2014, 57: 2334 - 2356).

[0122] 1.1.4 Synthesis of methyl 4-ethynyl-3-fluorobenzoate, 6

[0123] The synthesis of methyl 4-ethynyl-3-fluorobenzoate (6) is illustrated in Figure 1(d). Et3N (120 mL) was degassed by bubbling N2 through it for 1 h. Then compound 4 (5.0 g, 21.45 mmol), trimethylsilylacetylene (3.56 mL, 25.74 mmol), Pd(PPh3)Cl2 (301 mg, 0.429 mmol) and CuI (82 mg, 0.429 mmol) were added under N2, and the resulting suspension was stirred at room temperature for 16 h. The suspension was diluted with heptane and passed through / SiO2 and the extract was evaporated to give the crude oil (6.44 g). It was purified by dry column vacuum chromatography (100% heptane, to 9:1 heptane / EtOAc) and the separated product was further purified by Kugelrohr distillation (150 °C, 7.4 Torr) to give compound 5 (5.58 g, >100%) as a yellow oil, which was carried directly to the next step: 1 H NMR (400 MHz, CDCl3) δ 0.27 (s, 9H), 3.92 (s, 3H), 7.50 (dd, J = 8.0, 6.8 Hz, 1H), 7.71 (dd, J = 9.6, 1.5 Hz, 1H), 7.75 (dd, J = 8.0, 1.6 Hz, 1H). Compound 5 (5.58 g, 22.3 mmol) and K2CO3 (6.16 g, 44.6 mmol) were added to a MeOH:MTBE solution (5:50, 55 mL) and the resulting mixture was stirred at room temperature under N2 for 6 h. The solution was then diluted with EtOAc, washed with saturated NH4Cl, H2O and brine, dried (MgSO4) and evaporated to give a crude solid (3.6 g). It was purified by dry column vacuum chromatography (100% heptane, to 8:2 heptane / EtOAc) to give compound 6 (3.07 g, 80% over two steps) as a white solid: 1 H NMR (600 MHz, CDCl3) δ 3.45 (s, 1H), 3.92 (s, 3H), 7.53 (dd, J = 8.0, 6.8 Hz, 1H), 7.72 (dd, J = 9.6, 1.6 Hz, 1H), 7.77 (dd, J = 8.0, 1.6 Hz, 1H); 13 C NMR (151 MHz, CDCl3) δ 52.5, 76.3, 85.1 (d, J = 3.3 Hz), 115.3 (d, J = 16.0 Hz), 116.5 (d, J = 22.9 Hz), 124.9 (d, J = 3.7 Hz), 132.2 (d, J = 7.4 Hz), 133.9 (d, J = 1.3 Hz), 162.9 (d, J = 253.5 Hz), 165.3 (d, J = 2.7 Hz); 19 F NMR (376 MHz, CDCl3) δ -109.3; IR (ATR) ν 最大 / cm -1 3238 m, 3090 w, 2967 w, 2111 w, 1710 s, 1564 m, 1501 m, 1440 m, 1308 s, 1212 s, 766 s; MS (ASAP) m / z = 179.0 [M+H] + ; HRMS (ASAP) for C 10H8O2F[M+H] + Calculated value: 179.0508, measured value 179.0495.

[0124] 1.1.5 Synthesis of methyl 5-bromopyridine-2-carboxylate, 8

[0125] The synthesis of methyl 5-bromopyridine-2-carboxylate (8) is illustrated in Figure 1(e).

[0126] 5-Bromopyridine-2-carboxylic acid (20.0 g, 99.0 mmol) was suspended in MeOH (150 ml), then concentrated H2SO4 (5 mL) was carefully added and the resulting solution was stirred under reflux for 6 h. The solution was cooled, diluted with EtOAc, washed with H2O and brine (50 mL), dried (MgSO4) and evaporated to give a crude colorless solid. It was distilled in vacuo using a Kugelrohr (200 °C, 7.4 Torr), and the resulting white solid was further recrystallized from heptane / MeOH (10:1) to give compound 8 (17.21 g, 80%) as a white solid: 1 H NMR (700 MHz, CDCl3) δ 3.90 (s, 4H), 7.86 - 7.93 (m, 3H), 8.68 (d, J = 2.0 Hz, 1H); 13 C NMR (176 MHz, CDCl3) δ 52.8, 124.8, 126.0, 139.5, 146.0, 150.7, 164.7; v 最大 / cm -1 3059w, 3008w, 2957w, 1710s, 1571w, 1558w, 1436m, 1305s, 1131s, 696s; MS (ASAP): m / z = 216.0 [M+H] + ; HRMS (ASAP) for C 10 H9NOI[M+H] + Calculated value: 215.9660, measured value: 215.9664 (Tung et al., Eur. J. Med. Chem. 2017, 126, 1011 - 1020).

[0127] 1.1.6 Synthesis of 2,2,5,5-tetramethyladipic acid, 9

[0128] The synthesis of 2,2,5,5-tetramethyladipic acid (9) is illustrated in Figure 1(f). To a 2 L three-necked flask equipped with a mechanical stirrer was added H2O (600 mL), concentrated H2SO4 (7.5 mL), and then pivalic acid (51.0 g, 500 mmol), and the resulting slurry was cooled to 0 °C. Over 15 min, with vigorous stirring, a solution of H2O2 (30%, 43 mL) and FeSO4·7H2O (139.0 g, 500 mmol) in H2O (288 mL) and concentrated H2SO4 (27.5 mL) was added dropwise. After the addition was complete, the suspension was stirred for an additional 15 min, and then the solution was concentrated to approximately 250 mL. The precipitated solid was filtered and then further dried under vacuum using a rotary evaporator to give a crude residue. It was recrystallized from AcOH to give 9 (3.39 g, 3%) as a colorless crystalline solid: 1 1H NMR (400 MHz, DMSO-d6) δ 1.06 (s, 12H), 1.37 (s, 4H), 12.05 (s, 2H).

[0129] 1.1.7 Synthesis of 1,6-diethyl 2,2,5,5-tetramethyladipate, 10

[0130] The synthesis of 1,6-diethyl 2,2,5,5-tetramethyladipate (10) is illustrated in Figure 1(g). To a solution of 9 (3.39 g, 16.76 mmol) in EtOH (40 mL) was added concentrated H2SO4 (2 mL), and the resulting suspension was stirred at reflux for 16 h. The solution was cooled, and the solvent was evaporated to give a crude residue dissolved in EtOAc. The organic matter was washed with saturated NaHCO3, H2O, and brine, dried (MgSO4), and evaporated to give a crude oil (3.8 g). It was purified by SiO2 chromatography (95:5, heptane / EtOAc) to give 10 (3.41 g, 79%) as a colorless oil: 1 1H NMR (700 MHz, CDCl3) δ 1.14 (s, 11H), 1.24 (t, J = 7.1 Hz, 6H), 4.11 (q, J = 7.1 Hz, 4H); 13 13C NMR (176 MHz, CDCl3) δ 14.2, 25.0, 35.5, 41.8, 60.2, 177.7; IR (ATR) ν 最大 / cm -1 2978 m, 2934 w, 2880 w, 1726 s, 1475 m, 1308 m, 1176 s, 1110 m, 771 w; MS (ES): m / z = 259.5 [M+H] + .

[0131] 1.1.8 Trimethyl({3,3,6,6-tetramethyl-2-[(trimethylsilyl)oxy]cyclohex-1-en-1-yl}oxyyl)silane, Synthesis of 11

[0132] The synthesis of trimethyl({3,3,6,6-tetramethyl-2-[(trimethylsilyl)oxy]cyclohex-1-en-1-yl}oxy)silane 11 is illustrated in Figure 1(h). Under N2, sodium (1.20 g, 52.1 mmol) was added to anhydrous toluene (50 mL), and the resulting mixture was heated to reflux until the sodium melted. Then the flask was removed from the heat, and then 10 (2.69 g, 10.41 mmol) and chlorotrimethylsilane (6.72 mL, 53.0 mmol) were added, and then the resulting suspension was stirred at reflux overnight. Then the purple suspension was cooled and filtered under a stream of N2, washed with toluene and then with tetrahydrofuran (THF). Then the filtrate was evaporated to give a crude pale yellow oil (3.2 g), which was purified by Kugelrohr distillation (120 °C, 3.6 torr) to give 11 (2.64 g, 81%) as a clear oil: 1 1H NMR (400 MHz, CDCl3) δ 0.19 (s, 18H), 1.03 (s, 12H), 1.44 (s, 4H). All other data were consistent with the literature (Kikuchi et al. J. Med. Chem. 2000; 43: pp. 409 - 419).

[0133] 1.1.9 Synthesis of 3,3,6,6-tetramethylcyclohexane-1,2-dione, 12

[0134] The synthesis of 3,3,6,6-tetramethylcyclohexane-1,2-dione is illustrated in Figure 1(i). Over 5 min, bromine (0.42 mL, 8.2 mmol) was added dropwise to a solution of 11 (2.6 g, 8.2 mmol) in dichloromethane (DCM). The resulting yellow solution was stirred at RT for 1 h, then diluted with DCM and treated with saturated Na2S2O3, then washed with H2O, dried (MgSO4) and evaporated to give a crude yellow solid (1.5 g). It was purified by recrystallization from heptane to give 12 (1.07 g, 78%) as a yellow crystalline solid: 1 1H NMR (700 MHz, CDCl3) δ 1.14 (s, 4H), 1.85 (s, 12H); 13 13C NMR (176 MHz, CDCl3) δ 22.9, 34.7, 48.6, 207.3; IR (ATR) ν 最大 / cm -1 2973m, 2940w, 2870w, 1706s, 1599w, 1459m, 1372m, 1102m, 931m; MS (ES): m / z = 169.3 [M + H] +。All other data are consistent with the literature (Kikuchi et al. J. Med. Chem. 2000; 43: pp. 409 - 419).

[0135] 1.1.10 Synthesis of methyl 5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxaline-2-carboxylate, 13

[0136] The synthesis of methyl 5,5,8,8 - tetramethyl - 5,6,7,8 - tetrahydroquinoxaline - 2 - carboxylate 13 is illustrated in Figure 1(j). 12 (0.80 g, 4.76 mmol) and DL - 2,3 - diaminopropionic acid hydrochloride (0.67 g, 4.76 mmol) were combined in MeOH (30 mL). NaOH (0.76 g, 19.04 mmol) was added, and the resulting mixture was stirred at reflux for 24 h. The solution was then cooled to 0 °C, H2SO4 was carefully added, and the solution was stirred at reflux for an additional 6 h. The solution was cooled, and the solvent was evaporated to give a crude residue, which was dissolved in EtOAc, washed with saturated NaHCO3, H2O, and brine, dried (MgSO4) and evaporated to give a crude yellow oil (0.9 g). It was purified by SiO2 chromatography (95:5, heptane / EtOAc) to give 13 (0.633 g, 54%) as a colorless oil: 1 1H NMR (400 MHz, CDCl3) δ 1.33 & 1.36 (s, 12H), 1.81 (s, 4H), 3.98 (s, 3H), 9.00 (s, 1H). All other data are consistent with the literature (Kikuchi et al. J. Med. Chem. 2000; 43: pp. 409 - 419).

[0137] 1.1.11 Synthesis of (5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)methanol, 14

[0138] The synthesis of (5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)methanol 14 is illustrated in Figure 1(k). NaBH4 (2.33 g, 61.5 mmol) was added to a solution of 13 (5.09 g, 20.5 mmol) in THF (80 mL). The solution was then heated to reflux, and MeOH (16 mL) was slowly added over 1 h. The resulting solution was then stirred at reflux overnight. The solution was cooled, quenched with 1 M HCl, and then the solvent was evaporated. The residue was dissolved in DCM, washed with water, dried (MgSO4) and evaporated to give a crude yellow oil (4 g). It was purified by SiO2 chromatography (8:2, heptane / EtOAc, as the eluent) to give 14 (3.96 g, 88%) as a colorless oil: 11H NMR (400 MHz, CDCl3) δ 1.33 & 1.36 (s, 12H), 1.80 (s, 4H), 3.50 (br, 1H), 4.75 (s, 2H), 8.32 (s, 1H); all other data were consistent with the literature (Kikuchi et al. J. Med. Chem. 2000; 43: pp. 409 - 419).

[0139] 1.1.12 Synthesis of 5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxaline-2-carbaldehyde, 15

[0140] The synthesis of 5,5,8,8 - tetramethyl - 5,6,7,8 - tetrahydroquinoxaline - 2 - carbaldehyde 15 is illustrated in Figure 1(l). Under N2, oxalyl chloride (2.28 mL, 26.96 mmol) was added to anhydrous DCM (100 mL). The resulting solution was cooled to - 78 °C, after which DMSO (3.83 mL, 53.92 mmol) was added dropwise to keep the temperature below - 60 °C. The solution was stirred for 15 min, then 14 (3.96 g, 17.97 mmol, in 20 mL) as a solution in anhydrous DCM was added dropwise to keep the temperature below - 60 °C. The solution was stirred for an additional 15 min, then Et3N (18.03 mL, 129.38 mmol) was added. Then the solution was stirred for 10 min, then allowed to reach room temperature (RT) over 30 min. H2O was added, and the resulting mixture was diluted with DCM, washed with H2O, dried (MgSO4) and evaporated to give a crude oil (4 g). It was purified by dry column vacuum chromatography (DCVC) (heptane to 9:1 heptane / EtOAc) to give 15 (3.39 g, 86%) as a colorless oil that slowly crystallized: 1 1H NMR (700 MHz, CDCl3) δ 1.35 & 1.37 (s, 12H), 1.83 (s, 4H), 8.90 (s, 1H), 10.08 (s, 1H); 13 13C NMR (176 MHz, CDCl3) δ 29.7, 29.7, 33.8, 33.8, 37.4, 37.9, 139.8, 144.2, 159.0, 163.7, 193.4; IR (ATR) v 最大 / cm -1 2979m, 2964m, 2928m, 2862m, 2823w, 1707s, 1553m, 1457m, 1126s, 1078s, 737s; MS (ES): m / z = 219.3 [M + H] + ; HRMS (ES) for C 13 H 19 ON2 [M + H] +Calculated value: 216.1497, measured value 216.1503.

[0141] 1.1.13 Synthesis of dimethyl 1-diazo-2-oxopropylphosphonate, 16

[0142] The synthesis of dimethyl 1-diazo-2-oxopropylphosphonate 16 is illustrated in Figure 1(m). Under vigorous stirring, NaH (60% dispersion in mineral oil, 1.20 g, 30.00 mmol) was added portionwise to a solution of dimethyl 2-oxopropylphosphonate (4.49 mL, 32.5 mmol) in anhydrous toluene (30 mL) at 0 °C. After the evolution of gas ceased, 4-acetamidobenzenesulfonyl azide (7.21 g, 30.0 mmol), as a solution in anhydrous THF (10 mL), was added dropwise. The resulting suspension was stirred at RT for 16 h, after which heptane was added and the suspension was filtered through and rinsed with MTBE. The organic extracts were then evaporated to give a crude oil (5 g), which was purified by SiO2 chromatography (1:1, heptane / EtOAc) to give dimethyl 1-diazo-2-oxopropylphosphonate (3.14 g, 54%) as a pale yellow oil: 1 1H NMR (400 MHz, CDCl3) δ 2.24 (s, 3H), 3.82 (d, J = 11.9 Hz, 6H), and all other data were consistent with the literature (Pietruszka et al. Synthesis, 2006, pp. 4266 - 4268).

[0143] 1.1.14 Synthesis of 2-ethynyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxaline, 17

[0144] The synthesis of 2-ethynyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxaline 17 is illustrated in Figure 1(n). Under N2, K2CO3 (1.49 g, 10.80 mmol) and dimethyl 1-diazo-2-oxopropylphosphonate (0.98 mL, 6.48 mmol) were added to a solution of 15 (1.18 g, 5.40 mmol) in anhydrous MeOH (50 mL), and the resulting suspension was stirred at RT for 16 h. The solution was diluted with EtOAc, washed with 5% NaHCO3, H2O, and brine, dried (MgSO4) and evaporated to give a crude orange oil (0.4 g). It was purified by SiO2 chromatography (95:5, heptane / EtOAc, as eluent) to give 17 (0.84 g, 73%) as a colorless oil that slowly crystallized: 1 1H NMR (700 MHz, CDCl3) δ 1.30 & 1.31 (s, 12H), 1.77 (s, 4H), 3.22 (s, 1H), 8.45 (s, 1H); 1313C NMR (176 MHz, CDCl3) δ 29.6, 29.7, 33.8, 34.0, 37.2, 37.3, 79.0, 81.0, 135.4, 144.5, 158.1, 158.6; IR (ATR) ν 最大 / cm -1 3279 s, 2986 w, 2945 m, 2917 m, 2863 w, 2110 w, 1519 w, 1470 m, 1459 m, 1274 m, 1078 s, 674 s; MS (ES): m / z = 215.3 [M+H] + ; HRMS (ES) for C 14 H 19 N2 [M+H] + Calculated: 215.1548, found 215.1548.

[0145] 1.2 Synthesis of 3-Fluoro-4-[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)ethynyl]benzoic acid, DC526

[0146] The synthesis of the exemplary compound DC526 is illustrated in Figure 2 below.

[0147] Et3N (80 mL) was degassed by bubbling with N2 for 1 h. Then compound 1 (0.80 g, 2.55 mmol), compound 6 (0.54 g, 3.05 mmol), Pd(PPh3)Cl2 (179 mg, 0.255 mmol) and CuI (49 mg, 0.255 mmol) were added under N2, and the resulting suspension was stirred at room temperature for 72 h. The suspension was diluted with MTBE and passed through / SiO2, and the extract was evaporated to give a crude solid (1.1 g). It was purified by dry-column vacuum chromatography (100% heptane, to 95:5 heptane / EtOAc) to give compound 7 (0.82 g, 88%) as a colorless oil that slowly crystallized, which was carried directly to the next step. Compound 7 (0.80 g, 2.20 mmol) was dissolved in THF (40 mL), 20% NaOH (3 mL) was added, and the resulting solution was stirred at reflux for 16 h. The mixture was cooled, acidified to pH 1 with 5% HCl, extracted with EtOAc, washed with H2O and brine, dried (MgSO4) and evaporated to give a crude white solid, which was recrystallized from acetonitrile (MeCN) to give DC526 (0.60 g, 77%) as a colorless crystalline solid: 11H NMR (600 MHz, DMSO-d6) δ 1.24 & 1.26 (s, 12H), 1.64 (s, 4H), 7.32 (dd, J = 8.1, 1.8 Hz, 1H), 7.40 (d, J = 8.2 Hz, 1H), 7.53 (d, J = 1.8 Hz, 1H), 7.70 - 7.78 (m, 2H), 7.80 (dd, J = 7.9, 1.6 Hz, 1H), 13.44 (br, 1H); 13 13C NMR (151 MHz, DMSO-d6) δ 31.3, 31.4, 33.9, 34.1, 34.2, 34.3, 81.0, 97.4 (d, J = 3.1 Hz), 115.2, 115.3 (d, J = 15.8 Hz), 116.0 (d, J = 22.3 Hz), 118.5, 125.4 (d, J = 3.4 Hz), 127.1, 128.7, 129.6, 132.7 (d, J = 7.1 Hz), 133.6, 145.2, 146.5, 161.4 (d, J = 250.3 Hz), 165.7 (d, J = 2.5 Hz); 19 19F NMR (376 MHz, DMSO-d6) δ -110.0; IR (ATR) ν 最大 / cm -1 2967 m, 2928 m, 2857 m, 2210 w, 1686 s, 1617 m, 1566 m, 1421 m, 1307 m, 1218 m, 834 s, 764 m; MS (ASAP): m / z = 351.2 [M + H] + ; HRMS (ASAP) for C 23 H 24 O2F [M + H] + calcd: 351.1760, found 351.1766.

[0148] 1.3 5-[2-(5,5,8,8-Tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)ethynyl]pyridine-2-carboxylic acid, synthesis of DC528

[0149] The synthesis of exemplary compound DC528 is illustrated in Figure 2 below.

[0150] Degas Et3N / THF (1:1, 120 mL) by bubbling with N2 for 1 h. Add Pd(PPh3)2Cl2 (0.265 g, 0.38 mmol), CuI (0.072 g, 0.38 mmol), Compound 3 (0.8 g, 4.80 mmol) and Compound 8 (0.98 g, 4.52 mmol) under N2, and stir the resulting solution at 50 °C for 40 h. Dilute the solution with heptane and elute with heptane through / SiO2 plug. Then, wash the organic matter with saturated NH4Cl, H2O and brine, dry (MgSO4) and evaporate to give a crude brown solid (1.9 g). Purify it by dry column vacuum chromatography (100% heptane, to 8:2 heptane / EtOAc) to give Compound 9 (0.36 g, 27%) as a white solid, which is directly carried to the next step: 1 1H NMR (400 MHz, CDCl3) δ 1.29 (d, J = 7.9 Hz, 12H), 1.69 (s, 4H), 4.02 (s, 3H), 7.31 (d, J = 1.1 Hz, 2H), 7.51 (s, 1H), 7.94 (dd, J = 8.1, 2.1 Hz, 1H), 8.12 (dd, J = 8.1, 0.9 Hz, 1H), 8.85 (dd, J = 2.1, 0.9 Hz, 1H). Dissolve Compound 9 (0.33 g, 0.95 mmol) in THF (30 mL), add 20% NaOH (3 mL), and stir the resulting solution at reflux for 16 h. Cool the mixture, acidify to pH 1 with 5% HCl, extract with EtOAc, wash with H2O and brine, dry (MgSO4) and evaporate to give a crude white solid. Recrystallize it from MeCN to give DC528 (0.30 g, 96%) as a colorless crystalline solid: 1 1H NMR (700 MHz, DMSO-d6) δ 1.25 & 1.27 (s, 12H), 1.65 (s, 4H), 7.35 (dd, J = 8.1, 1.8 Hz, 1H), 7.41 (d, J = 8.1 Hz, 1H), 7.57 (d, J = 1.8 Hz, 1H), 8.06 (dd, J = 8.1, 0.9 Hz, 1H), 8.12 (dd, J = 8.1, 2.1 Hz, 1H), 8.85 (dd, J = 2.1, 0.9 Hz, 1H), 13.35 (s, 1H); 1313C NMR (176 MHz, DMSO-d6) δ 31.3, 31.4, 33.9, 34.1, 34.2, 34.3, 39.5, 84.8, 95.4, 118.4, 122.7, 124.3, 127.1, 128.7, 129.8, 139.5, 145.2, 146.4, 146.9, 151.3, 165.6; IR (ATR) ν 最大 / cm -1 3283br, 2955m, 2920m, 2856m, 2208m, 1752s, 1586m, 1336s, 1247m, 1017m, 833m; MS (ES): m / z = 334.2 [M+H] + ; HRMS (ES) for C 22 H 24 NO2 [M+H] + calcd: 334.1807, found 334.1808.

[0151] 1.4 Methyl 4-[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)ethynyl]benzoate, Synthesis of DC641

[0152] The synthesis of the exemplary compound DC641 is illustrated in Figure 2 . Et3N (20 mL) was degassed by bubbling with Ar for 1 h. Then methyl 4-iodobenzoate (0.31 g, 1.20 mmol), DC640 (0.30 g, 1.40 mmol), Pd(PPh3)2Cl2 (83 mg, 0.12 mmol), and CuI (22 mg, 0.12 mmol) were added under Ar, and the resulting suspension was stirred at RT for 16 h. The suspension was diluted with MTBE and passed through / SiO2, and the extract was evaporated to give a crude solid (0.5 g). It was purified by dry column vacuum chromatography (100% heptane to 85:15 heptane / EtOAc) to give an off-white solid, which was then recrystallized from MeOH to give DC641 (0.29 g, 71%) as a colorless crystalline solid, which was carried directly to the next step: 1 1H NMR (400 MHz, CDCl3) δ 1.33 & 1.35 (s, 12H), 1.81 (s, 4H), 3.94 (s, 3H), 7.64 - 7.71 (m, 2H), 8.01 - 8.08 (m, 2H), 8.52 (s, 1H).

[0153] 1.5 4-[2-(5,5,8,8-Tetramethyl-5,6,7,8-tetrahydroquinoxalin-2-yl)ethynyl]benzoic acid, Synthesis of DC645

[0154] The synthesis of the exemplary compound DC645 is illustrated in Figure 2 Dissolve DC641 (0.28 g, 0.8 mmol) in THF (20 mL), add 20% NaOH (2 mL), and reflux the resulting solution with stirring for 16 h. Cool the mixture, acidify to pH 1 with 5% HCl, extract with EtOAc, wash with H2O and brine, dry (MgSO4) and evaporate to give a crude white solid, which is recrystallized from MeCN to give DC645 (0.24 g, 89%) as a colorless crystalline solid: 1 1H NMR (700 MHz, DMSO-d6) δ 1.29 (s, 12H), 1.78 (s, 4H), 7.73 - 7.79 (m, 2H), 7.98 - 8.02 (m, 2H), 8.68 (s, 1H), 13.24 (br, 1H); 13 13C NMR (176 MHz, DMSO-d6) δ 29.4, 29.4, 33.1, 33.2, 37.0, 37.1, 88.9, 89.8, 125.2, 129.6, 131.3, 131.9, 135.2, 144.4, 157.6, 158.0, 166.5; IR (ATR) ν 最大 / cm -1 2961w, 2925w, 2958w, 2223w, 1683s, 1606m, 1558w, 1428m, 1282s, 862s, 769m; MS (ASAP): m / z = 334.2 [M] + ; HRMS (ASAP) for C 21 H 22 N2O2 [M] + Calculated: 334.1681, found 334.1686.

[0155] Example 2: Biological Evaluation:

[0156] 2.1 Genomic Activity of the Synthesized Retinoids

[0157] The genomic activity of the synthetic retinoids was evaluated by determining their efficiency in inducing transcription using the X-Gal assay. The X-Gal assay utilizes Sil-15 reporter cells in which the transcription of the LacZ gene is controlled by a promoter linked to a retinoic acid response element (RARE). After treating the reporter cells with retinoids, the ability of the compound to induce transcription can be obtained by monitoring and quantifying the activity of β-galactosidase produced by the reporter cells.

[0158] Sil-15 cells were plated at 100,000 cells per well in a 96-well plate coated with 0.1% gelatin. The next day, a series of dilutions of retinoid ligands prepared in Dulbecco's Modified Eagle's Medium (DMEM) containing 10% fetal calf serum (FCS) were added at concentrations ranging from 10 -6 M to 10 -14 M, and the plates were incubated overnight. All concentrations for the ATRA standard curve and other retinoid ligands were tested in triplicate.

[0159] The next day, the assay plates were washed twice with phosphate-buffered saline (PBS), fixed with 1% glutaraldehyde in PBS and 1 mM MgCl2 at 100 μl per well for 15 minutes, and washed twice with PBS. β-Galactosidase activity was detected by adding 100 μl of freshly prepared 0.2% X-Gal in PBS containing 1 mM MgCl2, 3.3 mM potassium ferricyanide, and 3.3 mM potassium ferrocyanide to each well. The plates were incubated at 37 °C in 5% CO2 for 6 hours, and the color change was detected by reading the plates at 650 nm on an Emax Precision Microplate Reader (Molecular Devices). 最大 The data obtained, as shown in Table 1 and

[0160] illustrated in Figure 3 , demonstrated that several synthetic retinoids showed greater genomic activity than the endogenous ligand (ATRA), as evidenced by their increased ability to induce transcription in reporter cells. Notably, DC527, DC540, DC525, DC528, DC526, and DC645 all exhibited increased genomic activity and potency when compared to retinoic acid (ATRA).

[0161] 2.2 Nongenomic activity of the synthetic retinoids

[0162] By using The Ultra ERK1 / 2 kit measures the ability of synthetic retinoids to induce phosphorylation of ERK1 / 2 to evaluate their non-genomic activity.

[0163] In this assay, SH-SY5Y cells (100,000 cells / well) were plated in 96-well plates and serum-starved in DMEM for 24 hours. Retinoids were tested at concentrations ranging from 10M-5M to 10M-11M and at a final concentration of 0.1% DMSO in the medium. The assay was performed on SH-SY5Y cells in serum-free DMEM, and the cells were stimulated with retinoids at 37 °C for 30 minutes.

[0164] At the end of the assay, the medium was removed and the cells were lysed in 50 μl of freshly prepared 1X lysis buffer (provided in the kit). At room temperature, the 96-well plate was agitated on an orbital shaker (SO1, Stuart Scientific) at approximately 350 rpm for 10 minutes.

[0165] Meanwhile, the activation buffer was diluted 25-fold in the reaction buffer. Under green light in a dark room, the acceptor beads were diluted 50-fold in the freshly prepared reaction mixture, while the donor beads were diluted 50-fold in the dilution buffer to obtain two final reaction mixtures.

[0166] Then 10 μl of the cell lysate from each well was transferred to a 384-well white Proxiplates plate (PerkinElmer), and 5 μl of each prepared acceptor and donor reaction mixture was added under green light in a dark room. The plate was wrapped with aluminum foil and incubated at room temperature for at least 3 hours. Reading was performed using the Envision system (PerkinElmer Life Sciences) using the settings for reading.

[0167] shown in Table 1 and Figure 4 illustrated in demonstrate the ability of retinoids to induce Erk 1 / 2 phosphorylation in SH-SY5Y cells. Several retinoids were identified as having higher potency and efficacy than retinoic acids such as DC527, DC540, DC528, DC526, and DC645, with DC525 being identified as having the highest potency.

[0168] 2.3 Induction of neurite outgrowth

[0169] The SY-SY5Y cells were plated at 10,000 cells / well in a 12-well plate containing acid-treated / poly-L-lysine-coated coverslips. After 24 hours, each retinoid was added to the medium at a concentration of 10 nM, and the plates were incubated for 5 days. After retinoid treatment, the SH-SY5Y cells on the coverslips were washed twice in PBS, fixed in 4% paraformaldehyde (PFA) for 20 minutes at room temperature, and washed twice with PBS.

[0170] For immunocytochemical staining of neurites, the cells on the coverslips were washed three times in PBS and incubated in blocking solution (10% donkey serum and 0.1% triton X-100 in PBS) for 1 hour at room temperature. The cells were then labeled by incubating overnight at 4 °C with a β-III tubulin primary antibody (Sigma-Aldrich) diluted 1:1000 in blocking buffer. After overnight incubation, the cells were washed three times with PBS containing 0.1% Triton X-100 solution (PBST), and then incubated with an anti-mouse monoclonal secondary antibody (1:300 in PBST; Jackson Immunoresearch) for 2 hours at room temperature. Finally, after three washes in PBST and a final wash in PBS, the coverslips were mounted on slides and stored at 4 °C.

[0171] ImageJ software with the NeuronJ plugin was used to quantify neurite outgrowth on the stained cells. For each experiment, 10 different randomly selected images were taken from each coverslip using a Nikon Eclipse E400 fluorescence microscope. Each image was converted to an 8-bit image (required for the NeuronJ plugin) and optimized using the brightness and contrast tools in GIMP (GNU Image Manipulation Program). For each image, the tracing tool in the NeuronJ plugin was used to draw individual trajectories for each distinguishable neurite. The neurite length was measured in pixels and converted to the corresponding length in μm depending on the magnification used. The average neurite length for each image was calculated by dividing the total neurite length of each image by the total number of neurites. Ten images per coverslip were measured, and the average for the entire coverslip was calculated. For each retinoid and concentration, the coverslips were in triplicate.

[0172] Figure 5The data shown demonstrate that several of the retinoids show the ability to induce neurite outgrowth in SY-SY5Y cells. In addition, cells treated with several of these compounds (DC527, DC525, DC528, DC526, and DC645) showed significantly greater average neurite length than cells treated with ATRA.

[0173] Table 1 below summarizes the genomic activity (transcriptional activity) and non-genomic activity (p-ERK1 / 2 activity) for the retinoid compounds tested, along with the increase in neurite outgrowth, and these results are graphed in Figure 5 It is apparent from the figure that compounds showing high potency in both genomic and non-genomic assays demonstrated increased neurite outgrowth induction. This suggests that "dual-acting" compounds, i.e., compounds that induce both genomic and non-genomic activity, may prove to be more effective in clinical use, allowing this dual assay approach to serve as a potentially powerful screening tool for new therapeutic compounds.

[0174]

[0175] Table 1: Genomic activity, non-genomic activity, and neurite outgrowth

[0176] 2.4 Regulation of Alzheimer's disease-related genes

[0177] To examine the possible effect of retinoids on the expression of genes involved in Alzheimer's disease, the expression of a panel of Alzheimer's disease-related genes was evaluated in primary neuronal / glial cultures from rats after treatment with retinoids.

[0178] Approximately 300,000 rat neurons / glial cells were first treated with 1 μg / ml lipopolysaccharide (Sigma-Aldrich) for 6 hours to induce inflammation. After induction of inflammation, the cells were treated with 10 nM retinoid for 24 hours. The retinoids that were shown to be most effective in previous assays were selected for these experiments. After treatment, RNA was extracted from the treated cells for qPCR analysis.

[0179] According to the manufacturer's protocol, total RNA was extracted using the Qiagen RNeasy Mini Kit (Cat. No. 74104, Qiagen). Briefly, cell and brain tissue samples were homogenized in 350 μl and 1200 μl of RLT buffer mixed with β-ME (at a ratio of 1 ml buffer: 10 μl β-ME), respectively. Then, the samples were centrifuged at 13,000 rpm for 3 min. First, the supernatant was mixed with 70% ethanol (Cat. No. E7023, Sigma-Aldrich) at a volume ratio of 1:1, and then transferred to a spin column placed in a collection tube. The samples were centrifuged at 10,000 rpm for 1 min to bind the RNA to the membrane of the spin column.

[0180] For on-column DNase digestion, the samples in the column were washed with 350 μl of RW1 buffer and centrifuged at 10,000 rpm for 1 min. Then, 80 μl of DNase mix (10 μl DNase and 70 μl RDD buffer; Cat. No. 79254, Qiagen) was added on top of each sample. The samples were incubated at room temperature for 15 min, and then 350 μl of RW1 buffer was added. The samples were centrifuged at 10,000 rpm for 1 min.

[0181] Then, 500 μl of RPE buffer (mixed with 100% ethanol at a ratio of 1:4) was added on top of the samples. The samples were centrifuged at 10,000 rpm for 1 min (this step was repeated 2 times). The spin column was centrifuged again at 13,000 rpm for 1 min to dry the membrane. The spin column was removed from the collection tube and placed into another 1.5 ml RNase-free collection tube. RNA was eluted by directly adding 30 μl of RNase-free water to the spin column membrane. The samples were incubated at room temperature for 5 min and then spun at 10,000 rpm for 1 min.

[0182] RNA concentration was measured using a NanoDrop TM 2000c spectrophotometer (Thermo Fisher Scientific). The instrument was calibrated using RNase-free water, which was used to elute RNA as a blank, and 2 μl of each RNA sample was used. The RNA samples were stored in a freezer at -70 °C to minimize RNA degradation.

[0183] The qPCR reaction was carried out using PerfeCTa SYBR Green SuperMix (Cat. No. 733-1246, VWR). 10 μl of the reaction mixture was added in triplicate to each well of a 384-well plate (Cat. No. 04729749001, Roche). Each reaction contained 2 μl of 4-fold diluted cDNA template, 5 μl of 2X SYBR green mix, and 250 nM primers.

[0184] Primers were designed using Primer-BLAST, with a melting temperature of approximately 60 °C. Before using the primers for qPCR, the primer specificity was checked by PCR, and the PCR products were sent for sequencing.

[0185] Standard curves (made using 5-fold dilutions of the stock cDNA) and blank controls were run for all primer sets tested in qPCR. The plate was then sealed and briefly centrifuged to ensure that all reagents were at the base of the wells. The plate was run on a Roche LightCycler 480, which was programmed to hold the plate at 95 °C for 5 min. Then, the qPCR run continued for 45 such cycles: 95 °C for 15 seconds (s), 60 °C for 15 s, and 72 °C for 15 s. Then, a melting curve was obtained by running the plate at 95 °C for 5 s, followed by 58 °C for 1 min.

[0186] The results were analyzed using the ΔΔCT method in LightCycler 480 1.5 software. For each experiment, the expression of the gene of interest was normalized with respect to an appropriate reference gene.

[0187] Figure 7 The data shown in demonstrate that DC645, DC528, and DC526 downregulate inflammatory genes (Ccl5, TNFα, and Nos2), and upregulate neuroprotective genes (Abca1, Abcg1, Igf1, and Igf2) and non-amyloid precursor pathway genes (Nep, Ide, and Adam10) that direct amyloid precursor protein along a pathway that does not generate toxic amyloid fragments.

[0188] Example 3: MDCK-MDR1 Permeability Assay:

[0189] This assay was used to measure the permeability of test compounds across MDCK-MDR1 cells in the apical-to-basolateral (A-B) and basolateral-to-apical (B-A) directions, and to determine the efflux ratio (ER), which indicates whether the compound undergoes active efflux. Thus, this assay is a valuable in vitro surrogate for blood-brain permeability and CNS exposure.

[0190] 3.1 Experimental procedures

[0191] MDCK-MDR1 cells obtained from NIH (Rockville, MD, USA) were used between passage numbers 6 - 30. The cells were seeded at 3.4×10 5 cells / cm 2 onto a Millipore Multiscreen Transwell plate. The cells were cultured in DMEM and the medium was changed on day 3. Permeability studies were conducted on day 4. Cell culture and assays were incubated at 37 °C in an atmosphere of 5% CO2 with 95% relative humidity. On the day of the assay, monolayers were prepared by rinsing both the apical and basolateral surfaces twice with Hanks balanced salt solution (HBSS) warmed to the desired pH of 37 °C. The cells were then incubated with HBSS at the desired pH in both the apical and basolateral compartments for 40 min to stabilize physiological parameters. A dosing solution was prepared by diluting the test compound with the assay buffer to give a final test compound concentration of 10 μM. Analytical standards were prepared from test compound DMSO dilutions and transferred into the buffer, maintaining a 1% v / v DMSO concentration; the buffer contained supplemented HBSS at pH 7.4. To evaluate A - B permeability, the HBSS was removed from the apical compartment and replaced with the test compound dosing solution. The apical compartment insert was then placed into a companion plate containing fresh buffer (with 1% v / v DMSO). To evaluate B - A permeability, the HBSS was removed from the companion plate and replaced with the test compound dosing solution. Fresh buffer (containing 1% v / v DMSO) was added to the apical compartment insert, which was then placed into the companion plate. At 60 min, the apical compartment insert and the companion plate were separated and the apical and basolateral samples were diluted for analysis. Test compound permeability was evaluated in duplicate. Compounds with known permeability characteristics were run as controls on each assay plate. The test compounds and control compounds were quantified by LC - MS / MS cassette analysis using a 7 - point calibration, with appropriate dilution of the samples. The starting concentration (C0) was determined from the dosing solution and the experimental recovery was calculated from C0 and the concentrations in both the apical and basolateral compartments.

[0192] 3.2 Data analysis

[0193] The permeability coefficient (P app ) of each compound was calculated by the following equation:

[0194]

[0195] where dQ / dt is the rate of drug permeation across the cells, C0 is the donor compartment concentration at time zero, and A is the area of the cell monolayer. C0 is obtained from the analysis of the dosing solution. The efflux ratio (ER) is calculated from the mean A - B and B - A data. This is derived as follows:

[0196]

[0197] 3.3. Biological Studies

[0198] The membrane permeability of many compounds of Formula I was measured in the previously described MDCK - MDR1 assay. The permeability (P app , nm / s) and efflux ratio (ER) of the compounds were determined and compared to the permeability and efflux ratio of the closely related reference compound EC23. The results are summarized in Table 2:

[0199]

[0200] Table 2: Permeability and Efflux Ratio of Compounds of Formula I Relative to Reference Compound EC23

[0201] The results shown in Table 2 demonstrate that in the MDCK - MDR1 assay, some compounds of Formula (I) can show considerable improvement in permeability and lack of efflux and, thus, can be expected to show considerable improvement in blood - brain barrier penetration and CNS exposure. Since the treatment of CNS disorders including ALS and Alzheimer's disease requires exposure of the CNS target to a therapeutically effective concentration that is high enough, it is clear that optimal CNS exposure is an essential property of drugs for treating these disorders. Thus, compared to the literature compound EC23, the compounds of Formula (I) studied show significantly improved drug - like properties. This improvement in CNS exposure represents a surprising and unexpected finding.

[0202] Example 4: Turbidimetric Aqueous Solubility

[0203] Example 4.1 Experimental Procedure

[0204] The test compound (10 mM in DMSO) was serially diluted to give solutions in DMSO at 0.1 mM, 0.3 mM, 1 mM and 3 mM. Each test compound concentration was then further diluted 1:100 in buffer (0.01 M phosphate buffered saline pH 7.4) such that the final DMSO concentration was 1% and the final test compound concentrations were 1 μM, 3 μM, 10 μM, 30 μM and 100 μM. The experiment was conducted at 37 °C and samples at each concentration were incubated in 7 parallel assay wells. The plate was incubated at 37 °C for 2 h and then absorbance was measured at 620 nm. The solubility of the sample was estimated from the concentration of the test compound that produced an increase in absorbance above the vehicle control (i.e., 1% DMSO in buffer).

[0205] 4.2 Biological studies

[0206] The solubility of many compounds of formula (I) was measured in the nephelometric water solubility assay described previously. The solubility of the compounds was determined and compared to the solubility of the closely related reference compound EC23. The results are summarized in Table 3:

[0207]

[0208] Table 3: Solubility of compounds of formula I relative to reference compound EC23.

[0209] The results shown in the table above demonstrate that the compounds of formula I can exhibit a substantial improvement in solubility and, thus, can also be expected to exhibit a substantial improvement in many biological properties including absorption and target exposure. Similarly, this represents a surprising and unexpected finding.

[0210] It will be understood that when, throughout the specification, compounds are described as being useful for treating conditions or diseases alleviated by activation of the retinoic acid receptor (RAR), this represents a disclosure of these compounds per se.

[0211] All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by an alternative feature serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a general series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel step or any novel combination of steps of any method or process so disclosed.

[0212] Regarding the use of substantially any plural and / or singular terms herein, those skilled in the art may appropriately translate the plural to the singular and / or the singular to the plural, according to context and / or application. Various singular / plural permutations may be expressly set forth herein for clarity.

[0213] Those skilled in the art will understand that, generally speaking, the terms used herein, and particularly the terms used in the appended claims, are generally intended to be "open" terms (e.g., the term "including" should be understood as "including but not limited to", the term "having" should be understood as "having at least", the term "includes" should be understood as "including but not limited to", etc.). Those skilled in the art will also understand that if an intention is to obtain a specific number of introduced claim recitations, such intention will be expressly recited in the claim, and where such recitation is absent, such intention is absent. For example, as an aid to understanding, the following appended claims may contain the use of introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to mean that the claim recitation introduced by the indefinite article "a" or "an" will limit any particular claim containing such introduced claim recitation to an embodiment containing only one such recitation, even when the same claim includes an introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be construed to mean "at least one" or "one or more"); this also applies to the use of definite articles for introducing claim recitations. Additionally, even if a specific number of introduced claim recitations are expressly recited, those skilled in the art will recognize that such recitations should be understood to mean at least the recited number (e.g., a bare recitation of "two recitations" without further modifiers means at least two recitations, or two or more recitations).

[0214] It will be understood that, for purposes of illustration, various embodiments of the present disclosure have been described herein, and various modifications can be made without departing from the scope of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, and the true scope is defined by the appended claims.

[0215] This application also relates to the following items:

[0216] 1. A compound of formula I:

[0217]

[0218] Wherein:

[0219] A 1 is N or CR 6 ;

[0220] A 2 is N or CR 7 ;

[0221] A 3 is N or CR 8 ;

[0222] R 6 and R 8 each independently is hydrogen, C1-C 10 alkyl, F, Br or Cl;

[0223] R 7 independently is hydrogen, C1-C 10 alkyl, F, Br, Cl or -OCR 9 wherein R 9 is H or C1-C6 alkyl;

[0224] R 1 to R 4 each independently is C1-C 10 alkyl, or R 1 and R 2 and / or R 3 and R 4 are linked to form a 3-membered ring; A 4 is N or CR 12 ;

[0225] A 5 is N or CR 13 ;

[0226] A 6 is N or CR 14 ;

[0227] A 7 is N or CR 15 ;

[0228] Each R 12 to R 15 independently is H, halogen or C1-C 10 haloalkyl; and

[0229] R 5 is -C(=O)R 16 or -C(=O)OR 16 wherein R 16 is H or C 1-10 alkyl;

[0230] Provided that at least one of A 1 to A 7 is N, or at least one of R 12 to R 15 is F, Cl or Br; and its isomers;

[0231] in free form or in salt form;

[0232] The compound is used for treating a condition or disease alleviated by activating a retinoic acid receptor (RAR).

[0233] 2. The compound according to item 1, wherein A 1 to A 3 at least one of which is N.

[0234] 3. The compound according to item 1, wherein A 1 and A 3 are N.

[0235] 4. The compound according to any one of the preceding items, wherein A 2 is CR 7 .

[0236] 5. The compound according to item 4, wherein R 7 is hydrogen.

[0237] 6. The compound according to any one of the preceding items, wherein R 5 is -COOH.

[0238] 7. The compound according to any one of the preceding items, wherein at least one of A 4 , A 5 or A 6 is CF.

[0239] 8. The compound according to item 1, the compound is selected from:[[]]

[0240]

[0241] 9. The compound according to item 8, the compound is selected from:[[]]

[0242]

[0243] 10. The compound according to any one of items 1 to 9, wherein the disease or condition alleviated by activating RAR is selected from amyotrophic lateral sclerosis (ALS), Parkinson's disease, multiple sclerosis (MS), Alzheimer's disease, early Alzheimer's disease, middle Alzheimer's disease, late Alzheimer's disease, cognitive impairment, memory impairment, memory defect, senile dementia, cognitive impairment, mild cognitive impairment, stroke, traumatic brain injury, epilepsy and spinal cord injury.

[0244] 11. Use of the compound of formula I as defined in any one of items 1 to 10 in the manufacture of a medicament for treating a disease or condition alleviated by activating RAR.

[0245] 12. A method of treating a patient suffering from a disease or condition alleviated by activating RAR, the method comprising administering to the patient a therapeutically effective amount of a compound of formula I, wherein formula I is as defined herein.

[0246] 13. A pharmaceutical composition comprising a compound of formula I as defined herein, optionally in combination with one or more pharmaceutically acceptable excipients, diluents or carriers, for the treatment of a disease or condition alleviated by activating RAR.

[0247] 14. A compound of formula I:

[0248]

[0249] wherein:

[0250] A 1 is N or CR 6 ;

[0251] A 2 is N or CR 7 ;

[0252] A 3 is N or CR 8 ;

[0253] R 6 and R 8 each independently is hydrogen, C1-C 10 alkyl, F, Br or Cl;

[0254] R 7 independently is hydrogen, C1-C 10 alkyl, F, Br, Cl or -OCR 9 wherein R 9 is H or C1-C6 alkyl;

[0255] R 1 to R 4 each independently is C1-C 10 alkyl, or R 1 and R 2 and / or R 3 and R 4 are joined to form a 3-membered ring;

[0256] A 4 is N or CR 12 ;

[0257] A 5 is N or CR 13 ;

[0258] A 6 is N or CR 14;

[0259] A 7 is N or CR 15 ;

[0260] Each R 12 to R 15 is independently H, halogen or C1-C 10 haloalkyl; and

[0261] R 5 is -C(=O)R 16 or -C(=O)OR 16 wherein R 16 is H or C 1-10 alkyl;

[0262] Provided that at least one of A 1 to A 3 is N, or A 4 is CR 12 or A 5 is CR 13 wherein at least one of R 12 / R 13 is halogen; and

[0263] its isomers;

[0264] in free form or in salt form.

[0265] 15. The compound according to item 14, wherein at least one of A 1 to A 3 is N, or A 4 is CR 12 or A 5 is CR 13 wherein at least one of R 12 / R 13 is F.

[0266] 16. The compound according to item 14 or item 15, wherein at least one of A 1 to A 3 is N.

[0267] 17. The compound according to any one of items 14 to 16, wherein both A 1 and A 3 are N.

[0268] 18. A method for screening a compound for therapeutic potential against a therapeutic condition or disease alleviated by activating RAR, the method comprising:

[0269] - determining the potency (E of the compound in activating RAR最大 )Determination as an indicator of genomic activity;

[0270] -Perform determination of the potency (E 最大 )Determination as an indicator of non-genomic activity;

[0271] For each determination, compare E 最大 with the baseline value; and

[0272] -Select those compounds with E higher than the baseline value in both determinations 最大 for further study.

[0273] 19. The method according to item 18, wherein the determination of the potency (E 最大 ) as an indicator of non-genomic activity is a kinase phosphorylation assay.

[0274] 20. The method according to item 19, wherein the kinase phosphorylation assay is an ERK1 / 2 phosphorylation assay.

Claims

1. Use of a compound of formula I in the manufacture of a medicament for the treatment of a condition or disease alleviated by activation of a retinoic acid receptor (RAR): wherein: A 1 is CR 6 ; A 2 is CR 7 ; A 3 is CR 8 ; R 6 and R 8 each independently is hydrogen, C1-C 10 alkyl, F, Br or Cl; R 7 is independently hydrogen, C1-C 10 alkyl, F, Br, Cl or -OCR 9 , where R 9 is H or C1-C6 alkyl; R 1 to R 4 each independently is C1-C 10 alkyl, or R 1 and R 2 and / or R 3 and R 4 are linked to form a 3-membered ring; A 4 is N or CR 12 ; A 5 is N or CR 13 ; A 6 is N or CR 14 ; A 7 is N or CR 15 ; Each R 12 to R 15 is independently H, halogen or C1-C 10 haloalkyl; and R 5 is -C(=O)R 16 or -C(=O)OR 16 , wherein R 16 is H or C 1-10 alkyl; The condition is A 4 to A 7 at least one of which is N, or R 12 to R 15 at least one of which is F, Cl or Br; the compound is in free form or in salt form.

2. Use according to claim 1, wherein R 7 is hydrogen.

3. Use according to claim 1 or claim 2, wherein R 5 is -COOH.

4. The use according to any one of claims 1 to 3, wherein A 4 , A 5 or A 6 is at least one of CF.

5. Use according to claim 1, wherein the compound of formula I is selected from:

6. Use according to claim 5, wherein the compound of formula I is selected from:

7. Use according to any one of claims 1 to 6, wherein the disease or condition alleviated by activation of RAR is selected from amyotrophic lateral sclerosis (ALS), Parkinson's disease, multiple sclerosis (MS), Alzheimer's disease, impaired memory, senile dementia, cognitive impairment, stroke, traumatic brain injury, epilepsy and spinal cord injury.

8. Use according to claim 7, wherein the disease or condition is selected from early Alzheimer's disease, middle Alzheimer's disease, late Alzheimer's disease, mild cognitive impairment, cognitive disorder and memory deficit.

9. A compound of formula I: wherein: A 1 is CR 6 ; A 2 is CR 7 ; A 3 is CR 8 ; R 6 and R 8 each independently is hydrogen, C1-C 10 alkyl, F, Br or Cl; R 7 is independently hydrogen, C1-C 10 alkyl, F, Br, Cl or -OCR 9 , where R 9 is H or C1-C6 alkyl; R 1 to R 4 each independently is C1-C 10 alkyl, or R 1 and R 2 and / or R 3 and R 4 are linked to form a 3-membered ring; A 4 is N or CR 12 ; A 5 is N or CR 13 ; A 6 is N or CR 14 ; A 7 is N or CR 15 ; Each R 12 to R 15 is independently H, halogen or C1-C 10 haloalkyl; and R 5 is -C(=O)R 16 or -C(=O)OR 16 , wherein R 16 is H or C 1-10 alkyl; The condition is A 4 is CR 12 or A 5 is CR 13 at least one of them, where R 12 / R 13 is a halogen; the compound is in free form or in salt form.

10. The compound according to claim 9, wherein A 4 is CR 12 or A 5 is CR 13 and at least one of them, wherein R 12 / R 13 is F.

11. The compound according to claim 9 or claim 10, wherein R 7 is hydrogen.

12. The compound according to any one of claims 9 to 11, wherein R 5 is -COOH.

13. The compound according to any one of claims 9 to 12, wherein the compound is selected from:

14. The compound according to claim 13, wherein the compound is selected from:

15. A pharmaceutical composition comprising a compound of formula I according to any one of claims 9 to 14, optionally in combination with one or more pharmaceutically acceptable carriers, for the treatment of a disease or condition alleviated by activation of RAR.

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