JP5247442B2 - Novel amyloid affinity compound - Google Patents

Description

The present invention relates to a compound used for diagnosis of head degenerative diseases. More specifically, the present invention relates to a compound useful for detecting amyloid at a lesion site in the diagnosis of a disease in which amyloid accumulates such as Alzheimer's disease.

Diseases that develop when fibrous proteins called amyloid are deposited in various organs or tissues in the body are collectively called amyloidosis. A common feature of amyloidosis is that a fibrous protein called amyloid rich in β-sheet structure is deposited in various organs or regions throughout the body, causing functional abnormalities in the organs and tissues.

Alzheimer's disease (hereinafter referred to as AD), which is a typical disease of amyloidosis, is known as a disease causing dementia. Since this disease is a disease in which amyloid gradually deposits in the brain and causes death, it can be said that it is a disease with high social interest compared to other amyloidosis. In recent years, in advanced countries, the number of AD patients has rapidly increased with the aging of society, which has become a social problem.

According to histopathological aspects, AD is characterized by three brain pathological findings: the appearance of senile plaques, neurofibrillary tangles, and extensive neuronal loss. Senile plaques are structures containing amyloid as a major component, and their appearance is considered to be a pathological finding in the brain that appears more than 10 years before the onset of AD, that is, clinical symptoms.

Diagnosis of AD is performed by performing various cognitive function evaluations (for example, Hasegawa scale, ADAS-JCog, MMSE, etc.) after supplementarily combining image diagnosis such as CT and MRI. However, such a method based on the evaluation of cognitive function has a drawback that the diagnostic sensitivity is low in the early stage of onset, and further, the diagnosis result is easily affected by the cognitive function inherent in each individual. In addition, since a biopsy of a diseased part is indispensable for a definitive diagnosis, it is virtually impossible to make a definitive diagnosis of AD during the lifetime of a patient (Non-patent Document 1).

On the other hand, amyloid composing senile plaques has been reported to be an aggregate of amyloid β protein (hereinafter referred to as Aβ), and the aggregate of Aβ can exhibit neuronal cytotoxicity by taking a β sheet structure. It has been reported by many studies. Based on these findings, the so-called “amyloid cascade hypothesis” has been proposed in which the deposition of Aβ in the brain is triggered, and the formation of neurofibrillary tangles and neuronal loss occur as downstream phenomena (non-patented). Reference 2).

Based on such facts, attempts have recently been made to detect AD in vivo using a compound having high affinity for amyloid as a marker.
Many of these intracerebral amyloid imaging probes have a high affinity for amyloid and a hydrophobic low-molecular compound having a high ability to migrate to the brain, such as various radionuclides such as ¹¹ C, ¹⁸ F and ¹²³ I. The compound labeled with Specific examples include 6-iodo-2- [4 ′-(N, N-dimethylamino) phenyl] benzothiazole (hereinafter referred to as TZDM) and 6-hydroxy-2- [4 ′-(N-methylamino) phenyl. ] Various thioflavin derivatives (Patent Literature 1, Non-Patent Literature 3) including benzothiazole (hereinafter referred to as 6-OH-BTA-1), (E) -4-methylamino-4′-hydroxystilbene (hereinafter referred to as “Ethylose”) , SB-13) and (E) -4-dimethylamino-4′-iodostilbene (hereinafter referred to as m-I-SB) (Patent Document 2, Non-Patent Document 4, Non-Patent Document) 5), 6-iodo-2- [4 ′-(N, N-dimethylamino) phenyl] benzoxazole (hereinafter referred to as IBOX), 6- [2- (fluoro) ethoxy] -2- [2- ( -Dimethylaminothiazol-5-yl) ethenyl] benzoxazole and other benzoxazole derivatives (Non-patent document 6, Non-patent document 7), 2- (1- {6-[(2-fluoroethyl) (methyl) Amino] -2-naphthyl} ethylidene) malononitrile (hereinafter referred to as FDDNP) and other DDNP derivatives (Patent Document 4, Non-Patent Document 8) and 6-iodo-2- [4 ′-(N, N-dimethylamino) ) Compounds in which imidazopyridine derivatives (Patent Document 3, Non-Patent Document 9) such as phenyl] imidazo [1,2-a] pyridine (hereinafter referred to as IMPY) are labeled with ¹¹ C or radioactive halogen have been reported. Yes. Furthermore, human imaging studies have been conducted on some of these diagnostic imaging probes, and it has been reported that AD patients show radioactive accumulation in the brain that is clearly different from normal cases (Non-patent Document 10). Non-Patent Document 11).

JP-T-2004-506723 JP 2005-504055 Gazette JP 2005-512945 A Japanese translation of PCT publication No. 2002-523383 J. A. Hardy & G. A. Higgins, “Alzheimer ’s Disease: The Amyloid Cascade Hypohesis.”, Science, 1992, 256, p.184-185 G. McKhann et al., “Clinical diagnosis of Alzheimer's disease: Report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer's Disease.”, Neurology, 1984, 34, p.939- 944 Z.-P. Zhuang et al., “Radioiodinated Styrylbenzenes and Thioflavins as Probes for Amyloid Aggregates.”, J. Med. Chem., 2001, 44, p.1905-1914 Masahiro Ono et al., “11C-labeled stilbene derivatives as Aβ-aggregate-specific PET imaging agents for Alzheimer ’s disease.”, Nuclear Medicine and Biology, 2003, 30, p.565-571 H. F. Kung et al., “Novel Stilbenes as Probes for amyloid plaques.”, J. American Chemical Society, 2001, 123, p.12740-12741 Zhi-Ping Zhuang et al., “IBOX (2- (4'-dimethylaminophenyl) -6- iodobensoxazole): a ligand for imaging amyloid plaques in the brain.”, Nuclear Medicine and Biology, 2001, 28, p.887- 894 Furumoto Y et al., “[11C] BF-227: A New 11C-Labeled 2-Ethenylbenzoxazole Derivative for Amyloid-β Plaques Imaging.”, European Journal of Nuclear Medicine and Molecular Imaging, 2005, 32, Sup.1, P759 Eric D. Agdeppa et al., “2-Dialkylamino-6-Acylmalononitrile Substituted Naphthalenes (DDNP Analogs): Novel Diagnostic and Therapeutic Tools in Alzheimer ’s Disease.”, Molecular Imaging and Biology, 2003, 5, p.404-417 Zhi-Ping Zhuang et al., “Structure-Activity Relationship of Imidazo [1,2-a] pyridines as Ligands for Detecting β-Amyloid Plaques in the Brain.”, J. Med. Chem, 2003, 46, p.237- 243 W. E. Klunk et al., “Imaging brain amyloid in Alzheumer ’s disease with Pittsburgh Compound-B.”, Ann. Neurol., 2004, 55, p.306-319 Nicolaas P. L. G. Verhoeff et al., “In-Vivo Imaging of Alzheimer Disease β-Amyloid With [11C] SB-13 PET.”, American Journal of Geriatric Psychiatry, 2004, 12, p.584-595

As described above, various compounds have been disclosed as diagnostic imaging probes for amyloid and are being studied for clinical application.
TZDM, compounds labeled with iodine IBOX and m-I-SB in ^[125 I] are results of experiments with normal mice, the time point of two minutes after the injection, all transferred into brain . However, these compounds do not have sufficient clearance from normal tissues, and show a tendency to gradually accumulate in the brain with the passage of time after administration (Japanese Patent Publication No. 2005-512945, Zhi-Ping Zhuang et al. al., Nuclear Medicine and Biology, 2001, 28, p. 887-894, HF Kung et al., J. Am. Chem. Soc., 2001, 123, p. 12740-12741). If the clearance from the normal tissue is not sufficient, there is a problem that sufficient contrast cannot be obtained at the amyloid accumulation site. The compound labeled with [ ¹¹ C] of SB-13 has been shown to have a clearance from normal tissues by an experiment using rats, but the clearance rate is not sufficiently high (Masahiro Ono) et al., Nuclear Medicine and Biology, 2003, 30, p.565-571).

On the other hand, compounds having an imidazopyridine skeleton such as IMPY have the property of moving into the brain after administration and accumulating in amyloid, and also have excellent properties such as rapid clearance from normal tissues, unlike the compounds described above. It has been clarified as a result of an experiment using a [ ¹²⁵ I] -labeled compound. However, IMPY is a compound that shows a positive result in a reverse mutation test, and in order to use this compound as an imaging diagnostic probe, it is necessary to pay sufficient attention to its dosage and dosage form. (International Publication No. 03/106439 Pamphlet)
FDDNP has also been reported to be positive in the reverse mutation test. (International Publication No. 03/106439 Pamphlet)

As an imaging diagnostic probe targeting amyloid, it has affinity for amyloid and maintains the excellent performance of IMPY such as sufficiently high clearance from normal tissues, while suppressing toxicity such as mutagenicity. Although it is preferred to use compounds, no compounds with such performance are currently disclosed.

The present invention has been made in view of the above circumstances, and it is intended to obtain a compound having affinity for amyloid, sufficiently high clearance from normal tissues, and suppressed toxicity such as mutagenicity. It was aimed.

The inventor has found that a compound group having an imidazopyridine-phenyl skeleton, in which oxygen is bonded to carbon of the phenyl group, can be obtained as a group of compounds satisfying the above conditions, and the present invention has been completed. did.

That is, the present invention provides the following formula (1):

で表される化合物及びその塩、並びに前記式（１）で表される化合物又はその塩を配合してなる低毒性アルツハイマー病診断剤である。

And a salt thereof, and a low toxicity Alzheimer's disease diagnostic agent comprising the compound represented by the formula (1) or a salt thereof.

In the formula (1), R ¹ is arbitrary from hydrogen, hydroxyl group, carboxyl group, sulfate group, amino group, nitro group, cyano group, alkyl substituent having 1 to 4 carbon atoms, or alkoxy substituent having 1 to 4 carbon atoms. Groups can be selected. R ¹ is preferably a hydroxyl group, an alkyl substituent having 1 to 4 carbon atoms, or an alkoxy substituent having 1 to 4 carbon atoms, and more preferably a hydroxyl group, a methyl substituent, or a methoxy substituent.
R ² can use any radioactive halogen substituent, and is preferably a halogen selected from ¹⁸ F, ⁷⁶ Br, ¹²³ I, ¹²⁴ I, ¹²⁵ I, or ¹³¹ I, and ¹⁸ F, ⁷⁶ Br, More preferably, a halogen selected from ¹²³ I or ¹²⁵ I is used, and ¹⁸ F is particularly preferable.
Moreover, m is an integer of 0-2.

According to another aspect of the present invention, for in vivo imaging of amyloid deposition, comprising the compound represented by the formula (1) or a salt thereof and a pharmaceutically acceptable carrier or excipient. A pharmaceutical composition is provided.
According to still another aspect of the present invention, there is provided a compound represented by the formula (1) or a salt thereof used for pharmaceutical use.
According to still another aspect of the present invention, there is provided a compound represented by the formula (1) or a salt thereof used for in vivo imaging of amyloid deposition.
According to still another aspect of the present invention, (a) administering a detectable amount of the compound represented by the formula (1) or a salt thereof;
(b) detecting binding of the compound or salt thereof to amyloid deposits in a patient;
A method for detecting amyloid deposits in a patient in vivo is provided.
According to a preferred embodiment of the present invention, the step (b) is performed by PET or SPECT imaging.

According to another aspect of the present invention, the following formula (2):

And a salt thereof are provided.

In the formula (2), R ³ is an arbitrary group selected from hydrogen, hydroxyl group, carboxyl group, sulfate group, amino group, nitro group, cyano group, alkyl substituent having 1 to 4 carbon atoms, or alkoxy substituent having 1 to 4 carbon atoms. Groups can be selected. R ³ is preferably a hydroxyl group, an alkyl substituent having 1 to 4 carbon atoms, or an alkoxy substituent having 1 to 4 carbon atoms, and more preferably a hydroxyl group, a methyl substituent, or a methoxy substituent.

R ⁴ may be a group selected from a non-radioactive halogen substituent, a methanesulfonic acid substituent, a trifluoromethanesulfonic acid substituent, or an aromatic sulfonic acid substituent.
As the non-radioactive halogen substituent, a halogen that can be a target in a nucleophilic substitution reaction using radioactive fluorine can be used, and preferably iodine or bromine can be used.
Moreover, m is an integer of 0-2.

According to the present invention, it is possible to obtain a compound and a low-toxicity Alzheimer's disease diagnostic agent having affinity for amyloid, sufficiently high clearance from normal tissues, and suppressed toxicity such as mutagenicity. It was.

Hereinafter, taking 6-methoxy-2- [4 ′-(3 ″ -paratoluenesulfonyloxypropoxy) phenyl] imidazo [1,2-a] pyridine as an example, the radiohalogen label according to one embodiment of the present invention A method for synthesizing a precursor compound of the compound will be described.

First, 2-bromo-3-hydroxypyridine is reacted with methyl iodide in the presence of sodium methoxide to synthesize 2-bromo-3-methoxypyridine. Next, nitration with a mixed acid of concentrated sulfuric acid-concentrated nitric acid is performed to convert to 2-bromo-3-methoxy-6-nitropyridine, and then reductive elimination of the bromo group and reduction of the nitro group with palladium carbon are performed. To synthesize 2-amino-5-methoxypyridine (FIG. 1, steps 1 to 3). In these series of reactions, the reaction conditions can be set according to a conventional method, for example, a method described in the literature (Joseph G. Lombardino, Journal of Medicinal Chemistry, 1981, 24, p. 39-42).

Separately, 4'-hydroxyacetophenone and cupric bromide are reacted to synthesize 2-bromo-4'-hydroxyacetophenone (FIG. 1, step 4). The reaction conditions at this time can be performed according to a conventional method, for example, a method described in the literature (King, L. Carroll and Ostrum, G. Kenneth, Journal of Organic Chemistry, 1964, 29 (12), p. 3459-3461).

Next, 2-bromo-4′-hydroxyacetophenone synthesized above is reacted with 2-amino-5-methoxypyridine to give 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a. Synthesize pyridine (FIG. 1, step 5). This step can be performed as follows.

First, 2-bromo-4′-hydroxyacetophenone and 2-amino-5-methoxypyridine are dissolved in an inert solvent such as acetonitrile and reacted at reflux temperature for 2 to 6 hours to give 2- (4′-hydroxy). Phenyl) -6-methoxyimidazo [1,2-a] pyridine hydrobromide is formed, resulting in a white precipitate. As the inert solvent at this time, in addition to acetonitrile, a solvent usually used in the same reaction such as methanol or acetone can be used. Moreover, the reaction temperature should just be the temperature which can be recirculated, for example, can be 90 degreeC, when acetonitrile is used as a solvent. It should be noted that the amount of the solvent used is sufficient if it is sufficient for the reaction. However, if it is too much, it is impossible to obtain a precipitate of the reaction product, so care must be taken. For example, when the reaction is carried out using 2-bromo-4'-hydroxyacetophenone equivalent to 10 mmol, a solvent of about 40 to 50 mL may be used.

Next, the reaction solution is filtered and the precipitate is filtered off. Then, the white precipitate is suspended in a methanol / water mixture (1: 1), and a precipitate in which a saturated aqueous sodium hydrogen carbonate solution is suspended is suspended. If added in a large excess, 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine is liberated and precipitation occurs. By filtering this newly generated precipitate, 2- (4'-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine, which is the target product of this step, can be obtained as crystals. The amount of the water / methanol mixture is not particularly limited as long as it is a sufficient amount for the reaction. However, if the amount is too large, the precipitation of crystals is hindered. For example, if 2-bromo-4'-hydroxyacetophenone equivalent to 10 mmol is used, a water / methanol mixture of about 40 to 100 mL may be used. Further, the amount of sodium hydrogen carbonate is not particularly limited as long as it is in a large excess with respect to the precipitate as a reaction substrate. For example, when the reaction is performed under the above conditions, about 25 mL of saturated hydrogen carbonate. An aqueous sodium solution may be added to the reaction solution.

Subsequently, the synthesized 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine and 1,3-propanediol monoparatoluenesulfonate are mixed into a mixed solution of tetrahydrofuran and N, N-dimethylformamide. 6-methoxy-2- [4 ′-(3 ″ -paratoluenesulfonyloxypropoxy) phenyl], which is the target product, is obtained by dissolving and adding triphenylphosphine and diisopropyl azodicarboxylate to this to carry out Mitsunobu reaction. Imidazo [1,2-a] pyridine can be obtained (FIG. 1, step 7). 2002, 4 (14), p.2329-2332.) Can be easily synthesized (FIG. 1, step 6), The amount used may be an excess amount relative to the reaction substrate, and is typically a mole relative to 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine, which is the reaction substrate. The amount of triphenylphosphine and diisopropyl azodicarboxylate may be in accordance with the conditions of general Mitsunobu reaction, and typically is 1,3- What is necessary is just to use about the same mole as propanediol monoparatoluenesulfonate.

The compound in which the 6-position is a hydroxy substituent is obtained by adding boron tribromide to 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine obtained in Step 5 above. After the demethylation reaction is performed, the 6-position hydroxyl group is protected with a tetrahydropyranyl group, etc., then the reaction of the above step 7 is performed, and finally the 6-position protection group is deprotected. Can do. In addition, the compound in which the substituent bonded to the carbon at the 6-position is a methyl substituent or an ethoxy substituent is substituted with 2-amino-5-methylpyridine and 2-amino-5-methoxypyridine in Step 4 above, respectively. 2-amino-5-ethoxypyridine may be used, and compounds having different substituent positions in the imidazo [1,2-a] pyridine ring, for example, compounds having a methyl substituent or a methoxy substituent bonded to the carbon at the 8-position In place of 2-amino-5-methoxypyridine in Step 4, 2-amino-3-methylpyridine and 2-amino-3-methoxypyridine may be used, respectively.

Next, taking the 2- [4 ′-(3 ″-[ ¹⁸ F] fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine as an example, the method for producing the radiohalogen-labeled compound according to the present invention Will be described.

In the production of 2- [4 ′-(3 ″-[ ¹⁸ F] fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine, first, a phase transfer catalyst and [ ¹⁸ F] fluoride ion are used. The [ ¹⁸ F] fluoride ion can be obtained by a known method, for example, by obtaining a proton irradiation using H ₂ ¹⁸ O concentrated water as a target. possible. in this ^case, the ^[18 F] fluoride ions are present in the _H ^{2 18} O enriched water to target. the ^[18 F] the _H ^{2 18} O enriched water containing fluoride ions in the anion exchange column Then, the fluorine is adsorbed and collected on the column and separated from H ₂ ¹⁸ O concentrated water, and then a potassium carbonate solution is passed through the column to give [ ¹⁸ F] fluoride ion. The mixture containing the phase transfer catalyst, [ ¹⁸ F] fluoride ion, and potassium ion can be obtained by eluting the solution and adding the phase transfer catalyst to dryness.

Here, as the phase transfer catalyst, various compounds having a property of forming an inclusion body with [ ¹⁸ F] fluoride ion can be used. Specifically, various compounds used for the production of radioactive fluorine-labeled organic compounds can be used, and 18-crown-6-ether and other various amino polyethers can be used. As the most preferable embodiment, cryptofix 222 (trade name, manufactured by Merck & Co., Inc.) can be used.

Next, a dimethylformamide solution of 6-methoxy-2- [4 ′-(3 ″ -paratoluenesulfonyloxypropoxy) phenyl] imidazo [1,2-a] pyridine, a labeling precursor, was prepared and prepared above. 2- [4 ′-(3 ″-[ ¹⁸ F] by adding a reaction condition to the mixture containing the phase transfer catalyst, [ ¹⁸ F] fluoride ion and potassium ion, and giving reaction conditions. ] Fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine is synthesized. The reaction conditions can be set according to the conditions in the 2- [18 ^F] other radioactive including the fluoro-2-deoxy -D- glucose fluorine-labeled compound. For example, conditions such that the reaction solution is reacted at about 90 to 130 ° C. for 5 to 10 minutes can be used.

The synthesis of other radiohalogen-labeled compounds can be performed by appropriately selecting a labeling precursor and a radiohalogen to be used, and giving reaction conditions according to known methods. For example, the synthesis of 2- [4 ′-(3 ″-[ ¹²³ I] iodopropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine can be synthesized using 2- [4 ′-(3 "-Chloropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine can be used for metathesis reaction with Na [ ^123I ] in acetone or methanol solvent.

The diagnostic agent according to the present invention is blended with water or physiological saline adjusted to an appropriate pH or Ringer's solution, if necessary, in the same manner as other generally known radioactive diagnostic agents. It can be prepared as a liquid. In this case, the concentration of the present compound needs to be not more than the concentration at which the stability of the blended present compound is obtained. The dose of the compound is not particularly limited as long as it is a concentration sufficient to image the distribution of the administered drug. For example, in the case of an iodine-123 labeled compound and a fluorine-18 labeled compound, about 50 to 600 MBq per adult with a body weight of 60 kg can be used by intravenous administration or local administration. The distribution of the administered drug can be imaged by a known method. For example, the iodine-123 labeled compound can be imaged using a SPECT apparatus, and the fluorine-18 labeled compound can be imaged using a PET apparatus. it can.

EXAMPLES Hereinafter, although an Example, a reference example, and a comparative example are described and this invention is demonstrated further in detail, the content of this invention is not limited to these.
In the following examples, the names of the respective compounds were defined as shown in Table 1.

Reference Example 1 Synthesis of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine (non-radioactive fluorinated product)

As a sample for examining the affinity, lipophilicity and mutagenicity of the compound according to the present invention to amyloid, 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-methoxyimidazo [1,2- a] A non-radioactive fluorinated product of pyridine was synthesized.

100.0 g (corresponding to 0.575 mol) of 2-bromo-3-hydroxypyridine was dissolved in 310 mL of dimethyl sulfoxide, and 575 mL (corresponding to 0.575 mol) of a 1 mol / L sodium methoxide-methanol solution was added thereto. Was heated to 90 ° C. and methanol was distilled off. After cooling the reaction solution to 10 ° C. or lower, 93.9 g (corresponding to 0.662 mol) of methyl iodide was added, and the mixture was stirred at room temperature for 20.5 hours. After completion of the reaction, the reaction solution was poured into ice water and extracted twice with chloroform. The combined chloroform layers were washed with 1 mol / L sodium hydroxide, then washed twice with saturated brine, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to give 2-bromo-3-methoxypyridine 65. 0.4 g (corresponding to 0.348 mol) was obtained (FIG. 2, step 1).

Concentrated sulfuric acid (262 mL) was cooled to −2 ° C., 90% nitric acid (262 mL) was carefully added thereto, and then 2-bromo-3-methoxypyridine (65.3 g, equivalent to 0.347 mmol) was carefully added. The reaction mixture was stirred in an ice bath for 10 minutes, then stirred at room temperature for 30 minutes, further heated to 55 ° C. and stirred for 1.5 hours. The reaction solution was cooled to room temperature and then poured into ice in small portions to form a precipitate. The precipitate was collected by filtration and washed with water. This was dried under reduced pressure in the presence of diphosphorus pentoxide to obtain 55.7 g (corresponding to 0.239 mol) of 2-bromo-3-methoxy-6-nitropyridine (FIG. 2, step 2).

25.6 g (corresponding to 0.239 mol) of 2-bromo-3-methoxy-6-nitropyridine was dissolved in 1700 mL of ethanol, 37.3 g of 10% palladium carbon (50% wet) was added under an argon stream, and then 1 water of hydrazine was added. 283 mL of Japanese product was added dropwise. The reaction mixture was heated to reflux for 70 minutes, the reaction solution was cooled to room temperature, palladium carbon was filtered, the filtrate was washed with ethanol, and the washing solution was combined with the filtrate. The solution was concentrated under reduced pressure, water (1300 mL) and concentrated aqueous ammonia (130 mL) were added, and the mixture was extracted 8 times with chloroform. The combined chloroform layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was distilled under reduced pressure to obtain 26.2 g (corresponding to 0.211 mol) of 2-amino-5-methoxypyridine ( FIG. 2, step 3).

50 mL of ethyl acetate was added to and suspended in 28.17 g (corresponding to 126 mmol) of cupric bromide, and 8.18 g (corresponding to 60.0 mmol) of 4'-hydroxyacetophenone was dissolved in a mixed solution of 50 mL of ethyl acetate and 50 mL of chloroform. The solution was added and heated to reflux. After 5 hours, the reaction solution was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (equivalent to 33.7 mmol) was obtained. (FIG. 2, step 4).

2-Bromo-4′-hydroxyacetophenone 2.15 g (equivalent to 10.0 mmol) and 2-amino-5-methoxypyridine 1.25 g (equivalent to 10.0 mmol) were dissolved in 50 mL of acetonitrile, and the oil bath was heated at 90 ° C. The mixture was heated to reflux for 3.5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off, washed with acetonitrile, and dried under reduced pressure. The obtained crude crystals were suspended in a mixture of 40 mL of water and 40 mL of methanol, about 20 mL of a saturated sodium hydrogen carbonate solution was added thereto, and the mixture was shaken for 5 minutes using an ultrasonic cleaner. The precipitate was filtered off from the resulting mixture, washed well with water, dried under reduced pressure, and 1.96 g of 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine (8 .16 mmol) (FIG. 2, step 5).

242 mg (corresponding to 1.0 mmol) of 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine, which has been sufficiently dried to remove water, was dissolved in 10 mL of N, N-dimethylformamide. 418 mg (equivalent to 3.0 mmol) of potassium carbonate was added. To this, 140 μL (corresponding to 1.5 mmol) of 1-bromo-3-fluoropropane was added and stirred at room temperature for 18 hours. After completion of the reaction, the reaction solution was poured into water and extracted three times with chloroform. The combined chloroform layers were washed once with water and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated. Recycle preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), column: JAIGEL 2H (product name, manufactured by Nihon Analytical Industrial Co., Ltd.) is connected to the crude product thus obtained. : Chloroform) and 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine (hereinafter referred to as Compound 1) 189 mg (0.63 mmol) Equivalent) was obtained (FIG. 2, step 6).

The NMR measurement results (internal standard substance: tetramethylsilane) of the obtained compound were as follows.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated chloroform, resonance frequency: 500 MHz): δ 7.83-7.79 (m, 2H), 7.64-7.63 (s, 1H), 7.56-7.54 (m, 1H), 7.48-7.45 (m, 1H), 6.95-6.92 (m, 2H), 6.93-6.90 (m, 1H), 4.65 (dt, ² J _HF = 47.0 Hz, J = 6.0 Hz, 2H), 4.11 (t, J = 6.0 Hz, 2H ), 3.75 (s, 3H), 2.17 (dquint, ³ J _HF = 25.9 Hz, J = 6.0 Hz, 2H).

¹³ C-NMR (solvent: deuterated chloroform, resonance frequency: 125 MHz): δ 158.48, 149.06, 145.42, 142.64, 126.93, 126.80, 119.39, 117.22, 114.58, 108.31, 107.39, 80.66 (d, ¹ J _CF = 164.6 Hz) , 63.46 (d, ³ J _CF = 5.8 Hz), 56.02, 30.33 (d, ² J _CF = 20.2 Hz).

¹⁹ F-NMR (solvent: deuterated chloroform, resonance frequency: 470 MHz): δ −221.94 (tt, ² J _HF = 47.0 Hz, ³ J _HF = 25.9 Hz).

Reference Example 2 Synthesis of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-hydroxyimidazo [1,2-a] pyridine (non-radioactive fluorinated product)

As a sample for investigating the affinity, fat solubility and mutagenicity of the compound according to the present invention to amyloid, 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-hydroxyimidazo [1,2- a] A non-radioactive fluorinated product of pyridine was synthesized.

31.11 g (equivalent to 178.88 mmol) of 2-bromo-3-hydroxypyridine was dissolved in 95.8 mL of dimethyl sulfoxide, and 89.9 mL (equivalent to 89.9 mmol) of 1 mol / L sodium methoxide-methanol solution was added thereto. Thereafter, the reaction solution was heated to 90 ° C. to distill off methanol. After cooling the reaction solution to 5 ° C. or lower, 29.2 g (equivalent to 205.62 mmol) of methyl iodide was added, and the mixture was stirred at room temperature for 17 hours. After completion of the reaction, the reaction solution was poured into ice water and extracted twice with chloroform. The combined chloroform layers were washed with 1 mol / L sodium hydroxide, then washed twice with saturated brine, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to give 2-bromo-3-methoxypyridine 20 .74 g (corresponding to 110.31 mmol) was obtained (FIG. 3, step 1).

After 83 mL of concentrated sulfuric acid was cooled to −5 ° C., 83 mL of 90% nitric acid was carefully added thereto, and then 20.69 g (corresponding to 110.04 mmol) of 2-bromo-3-methoxypyridine was carefully added. The reaction mixture was stirred in an ice bath for 5 minutes, then stirred at room temperature for 10 minutes, further heated to 55 ° C. and stirred for 1 hour. The reaction solution was cooled to room temperature and then poured into ice in small portions to form a precipitate. The precipitate was collected by filtration and washed with water. This was dried under reduced pressure in the presence of diphosphorus pentoxide to obtain 17.41 g (corresponding to 74.71 mmol) of 2-bromo-3-methoxy-6-nitropyridine (FIG. 3, step 2).

Dissolve 17.36 g (corresponding to 74.50 mmol) of 2-bromo-3-methoxy-6-nitropyridine in 520 mL of ethanol, add 11.63 g of 10% palladium carbon (50% wet) under an argon stream, and then add 1 water of hydrazine. 88.4 mL of the Japanese product was added dropwise. The mixture was heated to reflux for 45 minutes and then cooled to room temperature to filter palladium carbon. Further, the filtrate was washed with ethanol, and the washing solution was combined with the filtrate. The solution was concentrated under reduced pressure, 402 mL of water and 38 mL of concentrated aqueous ammonia were added, and the mixture was extracted 8 times with chloroform. The combined chloroform layers were dried over anhydrous sodium sulfate, concentrated under reduced pressure, and then distilled under reduced pressure to obtain 8.14 g (corresponding to 65.57 mmol) of 2-amino-5-methoxypyridine (FIG. 3, step 3).

13.50 g (corresponding to 59.66 mmol) of 4'-benzoyloxyacetophenone was dissolved in 1100 mL of methanol, 34.52 g (corresponding to 71.59 mmol) of tetra-n-butylammonium tribromide was added, and the mixture was stirred at room temperature overnight. After evaporating the solvent under reduced pressure, the residue was dissolved in ethyl acetate, washed twice with water and then with saturated brine. The ethyl acetate layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by silica gel column chromatography (eluent: hexane / methylene chloride = 1/1) to give 4′-benzoyloxy. There was obtained 13.38 g (corresponding to 43.84 mmol) of 2-bromoacetophenone (FIG. 3, step 4).

13.33 g (corresponding to 43.68 mmol) of 4'-benzoyloxy-2-bromoacetophenone and 5.67 g (corresponding to 45.67 mmol) of 2-amino-5-methoxypyridine were dissolved in 481 mL of ethanol and heated to reflux for 2 hours. After cooling the reaction solution, 6.64 g (corresponding to 79.09 mmol) of sodium hydrogen carbonate was added, and the reaction mixture was further heated to reflux for 4 hours. After completion of the reaction, the solvent was concentrated under reduced pressure, and the residue was dissolved in chloroform and washed with water. The chloroform layer was dried over anhydrous sodium sulfate, the solvent was distilled off, and the resulting crude product was purified by silica gel column chromatography (eluent: chloroform / ethyl acetate = 20/1) to give 2- (4 10.20 g (corresponding to 30.87 mmol) of '-benzoyloxyphenyl) -6-methoxyimidazo [1,2-a] pyridine was obtained (FIG. 3, step 5).

2.90 g (equivalent to 14.83 mmol) of 2- (4′-benzoyloxyphenyl) -6-methoxyimidazo [1,2-a] pyridine, which had been sufficiently dried and freed of water, was dissolved in 245 mL of chloroform, and −15 ° C. Until cooled. A solution obtained by dissolving 12.62 mL (equivalent to 133.48 mmol) of boron tribromide in 134 mL of dichloromethane was added dropwise thereto, and the mixture was warmed to room temperature and stirred for 17 hours. After completion of the reaction, the reaction solution was ice-cooled, 668 mL of methanol was added, and the mixture was further stirred at room temperature for 3 hours, and then the reaction mixture was concentrated under reduced pressure. To the resulting crude product, 290 mL of chloroform and 29 mL of methanol were added and repulped, and then the precipitate was filtered off. The precipitate separated by filtration was washed with chloroform and then dried under reduced pressure to give 3.00 g (corresponding to 13.28 mmol) of 2- (4′-hydroxyphenyl) -6-hydroxyimidazo [1,2-a] pyridine. Obtained (FIG. 3, step 6).

After dissolving 2.98 g (equivalent to 13.17 mmol) of 2- (4′-hydroxyphenyl) -6-hydroxyimidazo [1,2-a] pyridine in 114 mL of dimethylformamide, 2.19 g (equivalent to 15.8 mmol) of potassium carbonate. ) Was added and cooled to 4 ° C. A solution prepared by dissolving 1.59 mL (corresponding to 21.08 mmol) of methoxymethyl chloride in 4.8 mL of dimethylformamide was added dropwise thereto, and the reaction solution was warmed to room temperature and stirred for 21 hours. After completion of the reaction, the reaction solution was concentrated, and 57 mL of chloroform and 57 mL of methanol were added thereto for repulping, followed by filtration to separate a precipitate and a filtrate. The precipitate was washed with 114 mL of a chloroform-methanol mixture (1: 1), and the filtrates were combined and concentrated under reduced pressure. The obtained crude product was purified by silica gel column chromatography (eluent: chloroform / methanol = 10/1 → 5/1) to give 2- (4′-hydroxyphenyl) -4-methoxymethyl-6-methoxy. 2.03 g (5.78 mmol) of methoxyimidazo [1,2-a] pyridinium chloride was obtained (FIG. 3, step 7).

2- (4′-hydroxyphenyl) -4-methoxymethyl-6-methoxymethoxyimidazo [1,2-a] pyridinium chloride 2.01 g (corresponding to 5.73 mmol) was dissolved in 83.6 mL of dimethylformamide, and potassium carbonate was added. 3.17 g (corresponding to 22.92 mmol) and 1.62 g (corresponding to 11.46 mmol) of 1-bromo-3-fluoropropane were added and stirred overnight at room temperature. After completion of the reaction, the reaction solution was poured into water and extracted twice with chloroform while adding sodium chloride and salting out. The combined chloroform layers were washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated, and the resulting crude product was purified by silica gel column chromatography (eluent: chloroform / methanol = 10/1 → 5/1). Purification yields 1.95 g (corresponding to 4.57 mmol) of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -4-methoxymethyl-6-methoxymethoxyimidazo [1,2-a] pyridinium chloride. (FIG. 3, step 8).

2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -4-methoxymethyl-6-methoxymethoxyimidazo [1,2-a] pyridinium chloride (1.93 g, corresponding to 4.53 mmol) was dissolved in methanol (29 mL). Concentrated hydrochloric acid (0.95 mL) was added, and the mixture was heated to reflux for 2 hours, cooled, poured into water, sodium chloride was added, and the mixture was extracted twice with chloroform while salting out. The resulting crude product was purified by silica gel column chromatography (eluent: chloroform / methanol = 10/1 → 5/1) to give 2- [4 ′-(3 ″ -fluoropropoxy). Phenyl] -6-methoxymethoxyimidazo [1,2-a] pyridine (1.22 g, corresponding to 3.68 mmol) was obtained (FIG. 3, step). ).

1.18 g (corresponding to 3.57 mmol) of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-methoxymethoxyimidazo [1,2-a] pyridine was dissolved in 29 mL of isopropyl alcohol, and 0. 59 mL was added and heated to reflux for 23 hours After cooling, the reaction solution was poured into water, sodium chloride was added, and the mixture was extracted twice with chloroform while salting out.The combined chloroform layer was dried over anhydrous magnesium sulfate, and obtained. The crude product was purified by silica gel column chromatography (eluent: chloroform / methanol = 10/1) to give 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-hydroxyimidazo [1,2- a] 481 mg (corresponding to 1.68 mmol) of pyridine (hereinafter referred to as compound 2) was obtained (FIG. 3, step 10).

The NMR measurement result (internal standard substance: dimethyl sulfoxide) of the obtained compound was as follows.

NMR apparatus used: JNM-GSX-270 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated dimethyl sulfoxide, resonance frequency: 270 MHz): δ 8.52 (s, 2H), 8.30-8.25 (m, 1H), 7.85-7.79 (m, 1H), 7.67-7.62 (m, 1H ), 7.22-7.16 (m, 2H), 5.64 (s, 1H), 4.62 (dt, ² J _HF = 47.0 Hz, J = 5.9 Hz, 2H), 4.17 (t, J = 5.9 Hz, 2H), 2.14 (dquint, ³ J _HF = 26.2 Hz, J = 5.9 Hz, 2H).

Reference Example 3 Synthesis of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine (non-radioactive fluorinated product)

As a sample for investigating the affinity, lipophilicity and mutagenicity of the compound of the present invention for amyloid, 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine A non-radioactive fluorinated product was synthesized.

50 mL of ethyl acetate was added to 28.17 g (corresponding to 126 mmol) of cupric bromide and suspended, and 8.18 g (corresponding to 60.0 mmol) of 4'-hydroxyacetophenone was dissolved in a mixed solution of 50 mL of ethyl acetate and 50 mL of chloroform. The solution was added and heated to reflux. After 5 hours, the reaction mixture was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (equivalent to 33.7 mmol) was obtained. (FIG. 4, step 1).

649 mg (corresponding to 3.0 mmol) of 2-bromo-4'-hydroxyacetophenone and 285 mg (corresponding to 3.0 mmol) of 2-aminopyridine were dissolved in 20 mL of acetonitrile and heated to reflux in an oil bath at 110 ° C. for 1 hour. After the reaction solution was cooled to room temperature, 254 mg (equivalent to 5.4 mmol) of sodium bicarbonate was added, and the mixture was further heated to reflux in an oil bath at 100 ° C. for 1 hour. After completion of the reaction, the reaction solution was cooled to room temperature, the precipitate was filtered off, and the obtained precipitate was washed with acetonitrile and water. This was dried under reduced pressure to obtain 405 mg (corresponding to 1.9 mmol) of 2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine (FIG. 4, step 2).

398 mg (corresponding to 1.89 mmol) of 2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine, which was sufficiently dried to remove water, was dissolved in 15 mL of N, N-dimethylformamide, and 788 mg of potassium carbonate was added thereto. (Corresponding to 5.7 mmol) was added. To this was added 260 μL of 1-bromo-3-fluoropropane (equivalent to 2.8 mmol), and the mixture was stirred at room temperature for 20.5 hours. After completion of the reaction, the reaction solution was poured into water and extracted three times with chloroform. The combined chloroform layers were washed with water and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated. Recycle preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), column: JAIGEL 2H (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), two connected crude phases of the obtained crude product, mobile phase : Chloroform) to obtain 264 mg (corresponding to 0.98 mmol) of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine (hereinafter referred to as Compound 3). (FIG. 4, step 3).

The NMR measurement results (internal standard substance: tetramethylsilane) were as follows.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated chloroform, resonance frequency: 500 MHz): δ 8.09 (dt, J = 6.9, 1.2 Hz, 1H), 7.90-7.86 (m, 2H), 7.76 (d, J = 0.7 Hz, 1H ), 7.62-7.59 (m, 1H), 7.14 (ddd, J = 9.1, 6.7, 1.2 Hz, 1H), 6.99-6.95 (m, 2H), 6.75 (dt, J = 6.7, 1.2 Hz, 1H), 4.67 (dt, ² J _HF = 47.0 Hz, J = 6.0 Hz, 2H), 4.14 (t, J = 6.0 Hz, 2H), 2.19 (dquint., ³ J _HF = 25.9 Hz, J = 6.0 Hz, 2H) .

¹³ C-NMR (solvent: deuterated chloroform, resonance frequency: 125 MHz): δ158.74, 145.68, 145.61, 127.29, 126.67, 125.42, 124.41, 117.29, 114.69, 112.21, 107.21, 80.73 (d, ¹ J _CF = 164.6 Hz ), 63.53 (d, ³ J _CF = 5.3 Hz), 30.42 (d, ² J _CF = 20.2 Hz).

¹⁹ F-NMR (solvent: deuterated chloroform, resonance frequency: 470 MHz): δ-222.04 (dd, ² J _HF = 47.0 Hz, ³ J _HF = 25.9 Hz).

Reference Example 4 Synthesis of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-iodoimidazo [1,2-a] pyridine (non-radioactive fluorinated product)

For the purpose of preparing a calculation formula for use in calculating the logP _HPLC of the compound according to the present invention, the non-reactivity of 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-iodoimidazo [1,2-a] pyridine Radiofluorinated product was synthesized.

50 mL of ethyl acetate was added and suspended in 28.17 g (corresponding to 126 mmol) of cupric bromide, and a mixed solution of 8.18 g (corresponding to 60.0 mmol) of 4′-hydroxyacetophenone in 50 mL of ethyl acetate and 50 mL of chloroform was added thereto. Heated to reflux. After 5 hours, the reaction solution was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (corresponding to 33.7 mmol) was obtained (FIG. 5, step 1).

441 mg (corresponding to 2.0 mmol) of 2-bromo-4′-hydroxyacetophenone and 449 mg (corresponding to 2.0 mmol) of 2-amino-5-iodopyridine are dissolved in 15 mL of acetonitrile and heated to reflux in an oil bath at 110 ° C. for 5 hours. did. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off, washed with acetonitrile, and dried under reduced pressure. The obtained crude crystals were suspended in a mixed solution of 10 mL of water and 10 mL of methanol, about 10 mL of a saturated sodium bicarbonate solution was added thereto, and the mixture was shaken with an ultrasonic cleaner for 5 minutes. From the resulting mixture, the precipitate was filtered off, washed well with water, dried under reduced pressure, and 526 mg (1.56 mmol) of 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine. Equivalent) was obtained (FIG. 5, step 2).

673 mg (corresponding to 2.0 mmol) of 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine, which has been sufficiently dried to remove water, was dissolved in 25 mL of N, N-dimethylformamide. To this was added 831 mg (equivalent to 6.0 mmol) of potassium carbonate. To this was added 275 μL (corresponding to 3.0 mmol) of 1-bromo-3-fluoropropane, and the mixture was stirred at room temperature for 24 hours. After completion of the reaction, the reaction solution was poured into water and extracted three times with chloroform. The combined chloroform layers were washed with water and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated. The obtained crude product was purified by flash silica gel column chromatography (eluent: chloroform), and further recycled preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), column: JAIGEL 2H (Product name, manufactured by Nihon Analytical Industrial Co., Ltd.) and purified using 2-linked, mobile phase: chloroform) to give 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-iodoimidazo [1, 2-a] 349 mg (corresponding to 0.881 mmol) of pyridine was obtained (FIG. 5, step 3).

The NMR measurement result (internal standard substance: tetramethylsilane) of the obtained 2- [4 ′-(3 ″ -fluoropropoxy) phenyl] -6-iodoimidazo [1,2-a] pyridine is as follows. there were.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated chloroform, resonance frequency: 500 MHz): δ 8.37-8.35 (m, 1H), 7.88-7.84 (m, 2H), 7.72 (s, 1H), 7.42-7.39 (m, 1H ), 7.32 (dd, J = 9.4, 1.6 Hz, 1H), 6.99-6.96 (m, 2H), 4.67 (dt, ² J _HF = 47.0 Hz, J = 6.0 Hz, 2H), 4.15 (t, J = 6.0 Hz, 2H), 2.20 (dquint, ³ J _HF = 25.9 Hz, J = 6.0 Hz, 2H).

¹³ C-NMR (solvent: deuterated chloroform, resonance frequency: 125 MHz): δ159.01, 146.23, 144.16, 132.36, 130.28, 127.42, 126.05, 118.31, 114.77, 106.90, 80.72 (d, ¹ J _CF = 164.6 Hz), 74.80, 63.57 (d, ³ J _CF = 5.3 Hz), 30.42 (d, ² J _CF = 20.2 Hz).

¹⁹ F-NMR (solvent: deuterated chloroform, resonance frequency: 470 MHz): δ-222.09 (dd, ² J _HF = 47.0 Hz, ³ J _HF = 25.9 Hz).

Reference Example 5 Synthesis of 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine

Synthesis of a non-radioactive fluorinated product of 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine for the purpose of creating a calculation formula used for calculation of logP _HPLC of the compound according to the present invention. Went.

50 mL of ethyl acetate was added and suspended in 28.17 g (corresponding to 126 mmol) of cupric bromide, and a mixed solution of 8.18 g (corresponding to 60.0 mmol) of 4′-hydroxyacetophenone in 50 mL of ethyl acetate and 50 mL of chloroform was added thereto. Heated to reflux. After 5 hours, the reaction solution was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (corresponding to 33.7 mmol) was obtained (FIG. 6, step 1).

441 mg (corresponding to 2.0 mmol) of 2-bromo-4′-hydroxyacetophenone and 449 mg (corresponding to 2.0 mmol) of 2-amino-5-iodopyridine are dissolved in 15 mL of acetonitrile and heated to reflux in an oil bath at 110 ° C. for 5 hours. did. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off, washed with acetonitrile, and dried under reduced pressure. The obtained crude crystals were suspended in a mixed solution of 10 mL of water and 10 mL of methanol, about 10 mL of a saturated sodium bicarbonate solution was added thereto, and the mixture was shaken with an ultrasonic cleaner for 5 minutes. From the resulting mixture, the precipitate was filtered off, washed well with water, dried under reduced pressure, and 526 mg (1.56 mmol) of 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine. Equivalent) was obtained (FIG. 6, step 2).

The NMR measurement results (internal standard substance: dimethyl sulfoxide) of the obtained 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine were as follows.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated dimethyl sulfoxide, resonance frequency: 500 MHz): δ8.86-8.84 (m, 1H), 8.14 (s, 1H), 7.78-7.74 (m, 2H), 7.40-7.35 (m, 2H), 6.86-6.82 (m, 2H).

¹³ C-NMR (solvent: deuterated dimethyl sulfoxide, resonance frequency: 125 MHz): δ 158.08, 145.87, 143.87, 132.48, 131.72, 127.67, 124.99, 118.14, 116.14, 108.02, 75.85.

Reference Example 6 Synthesis of [ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine

[ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] is prepared in accordance with the following steps for the purpose of creating a calculation formula used for calculation of LogP _HPLC . Pyridine was synthesized.

50 mL of ethyl acetate was added to 28.17 g (corresponding to 126 mmol) of cupric bromide and suspended, and 8.18 g (corresponding to 60.0 mmol) of 4'-hydroxyacetophenone was dissolved in a mixed solution of 50 mL of ethyl acetate and 50 mL of chloroform. The solution was added and heated to reflux. After 5 hours, the reaction mixture was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (corresponding to 33.7 mmol) was obtained (FIG. 7, step 1).

2-Bromo-4′-hydroxyacetophenone 2.15 g (equivalent to 10.0 mmol) and 2-amino-5-bromopyridine 1.74 g (equivalent to 10.0 mmol) were dissolved in 50 mL of acetonitrile, and the oil bath was heated at 105 ° C. Heated to reflux for 6 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off, washed with acetonitrile, and dried under reduced pressure. The obtained crude crystals were suspended in a mixed solution of 20 mL of water and 20 mL of methanol, about 25 mL of a saturated sodium hydrogen carbonate solution was added thereto, and the mixture was shaken with an ultrasonic cleaner for 5 minutes. The precipitate was filtered off from the resulting mixture, washed well with water, and dried under reduced pressure to give 2.41 g of 6-bromo-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine (8 .32 mmol) (FIG. 7, step 2).

290 mg (corresponding to 1.0 mmol) of 6-bromo-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine, which had been sufficiently dried to remove water, was dissolved in 10 mL of N, N-dimethylformamide. To this was added 413 mg (corresponding to 3.0 mmol) of potassium carbonate. To this was added 138 μL (corresponding to 1.5 mmol) of 1-bromo-3-fluoropropane, and the mixture was stirred at room temperature for 20.5 hours. After completion of the reaction, the reaction solution was poured into water and extracted three times with chloroform. The combined chloroform layers were washed with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated. Recycle preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), column: JAIGEL 2H (product name, manufactured by Nihon Analytical Industrial Co., Ltd.), two connected crude phases of the obtained crude product, mobile phase : Chloroform) to give 302 mg (corresponding to 0.866 mmol) of 6-bromo-2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine (FIG. 7). Step 3).

6-Bromo-2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine 85 mg (equivalent to 0.24 mmol) was dissolved in 10 mL of dioxane, and 2 mL of triethylamine was added thereto. 185 μL (corresponding to 0.36 mmol) of bistributyltin and 20 mg (catalytic amount) of tetrakistriphenylphosphine palladium were added to the reaction mixture, and the reaction mixture was stirred at 90 ° C. for 24 hours, after which the solvent was distilled off under reduced pressure, The product was purified by TLC (eluent: hexane / ethyl acetate = 6/4), and the resulting crude product was further subjected to recycle preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nippon Analytical Industrial Co., Ltd.), column). : JAIGEL 2H (product name, manufactured by Nippon Analytical Industrial Co., Ltd.) , 6-tributylstannyl-2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine (42 mg, corresponding to 74.2 μmol) was obtained (FIG. 7, step 4).

NMR measurement results (internal standard substance: tetramethylsilane) of the resulting 6-tributylstannyl-2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine were as follows: It was street.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated chloroform, resonance frequency: 500 MHz): δ8.01-7.93 (m, 1H), 7.91-7.87 (m, 2H), 7.75-7.74 (m, 1H), 7.63-7.58 (m , 1H), 7.20-7.11 (m, 1H), 7.00-6.95 (m, 2H), 4.67 (dt, J _HF = 47.0 Hz, J = 6.0 Hz, 2H), 4.15 (t, J = 6.0 Hz, 2H ), 2.20 (dquint, J _HF = 26.1 Hz, J = 6.0 Hz, 2H), 1.64-1.47 (m, 6H), 1.39-1.31 (m, 6H), 1.19-1.04 (m, 6H), 0.91 (t , J = 7.2 Hz, 9H)

6-tributylstannyl-2- [4 ′-(3 ″ -fluoropropoxy) phenyl] imidazo [1,2-a] pyridine in methanol (concentration: 1 mg / mL) 100 μL, 1 mol / L hydrochloric acid 50 μL, 37 ˜370 MBq of [ ¹²⁵ I] sodium iodide 10-100 μL, 10% (W / V) hydrogen peroxide 20 μL was added, and the mixture was allowed to stand at room temperature for 10 minutes and then subjected to HPLC under the following conditions. Then, [ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine fraction was collected (FIG. 7, step 5).

HPLC conditions:
Column: Phenomenex Luna C18 (trade name, manufactured by Phenomenex, size: 4.6 × 150 mm)
Mobile phase: 0.1% trifluoroacetic acid / acetonitrile containing 0.1% trifluoroacetic acid = 80/20 → 0/100 (17 minutes)
Flow rate: 1.0 mL / min Detector: UV-visible absorptiometer (detection wavelength: 282 nm) and radiation detector (STEFI type, Raytest)

A liquid obtained by adding 10 mL of water to the fraction was passed through a Sep-Pak C18 column (trade name: Sep-Pak (registered trademark) Light C18 Cartridges, manufactured by Waters, a packing amount of a filler of 130 mg), and [ ¹²⁵ I ] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine was adsorbed and collected on the column. After washing the column with 1 mL of water, 1 mL of ethanol was collected. Then, [ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine was eluted. The amount of radioactivity obtained was immediately after synthesis. In addition, when TLC analysis was performed under the following conditions, its radiochemical purity was 96.5%.

TLC analysis conditions:
TLC plate: RP-18F254 (product name, manufactured by Merck & Co., Inc.)
Developing phase: methanol / water = 20/1
Detector: Bioimaging analyzer, BAS-2500 (Type: BAS-2500, manufactured by Fuji Photo Film Co., Ltd.)

Reference Example 7 Synthesis of [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine

[ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine was synthesized according to the following steps for the purpose of creating a calculation formula used for calculation of LogP _HPLC .

50 mL of ethyl acetate was added to 28.17 g (corresponding to 126 mmol) of cupric bromide and suspended, and 8.18 g (corresponding to 60.0 mmol) of 4'-hydroxyacetophenone was dissolved in a mixed solution of 50 mL of ethyl acetate and 50 mL of chloroform. The solution was added and heated to reflux. After 5 hours, the reaction mixture was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (corresponding to 33.7 mmol) was obtained (FIG. 8, step 1).

2-Bromo-4′-hydroxyacetophenone 2.15 g (equivalent to 10.0 mmol) and 2-amino-5-bromopyridine 1.74 g (equivalent to 10.0 mmol) were dissolved in 50 mL of acetonitrile, and the oil bath was heated at 105 ° C. Heated to reflux for 6 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off, washed with acetonitrile, and dried under reduced pressure. The obtained crude crystals were suspended in a mixed solution of 20 mL of water and 20 mL of methanol, about 25 mL of a saturated sodium hydrogen carbonate solution was added thereto, and the mixture was shaken with an ultrasonic cleaner for 5 minutes. The precipitate was filtered off from the resulting mixture, washed well with water, and dried under reduced pressure to give 2.41 g of 6-bromo-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine (8 .32 mmol) (FIG. 8, step 2).

138 mg (corresponding to 0.476 mmol) of 6-bromo-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine was dissolved in 20 mL of dioxane, 2 mL of triethylamine was added, and then 360 μL (0.713 mmol) of bistributyltin. Equivalent) and 20 mg (catalytic amount) of tetrakistriphenylphosphine palladium. After stirring the reaction mixture at 90 ° C. for 22 hours, the solvent was distilled off under reduced pressure, and the residue was purified by preparative TLC (eluent: hexane / ethyl acetate = 1/4). Further, the obtained crude product was recycle preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nihon Analytical Industrial)), column: JAIGEL 2H (product name, manufactured by Nihon Analytical Industrial), connected and moved. Phase: chloroform) to obtain 47 mg (corresponding to 94.9 μmol) of 6-tributylstannyl-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine (FIG. 8, step 3). ).

To 53 μL of 6-tributylstannyl-2- (4′-hydroxyphenyl) imidazo [1,2-a] pyridine in methanol (concentration: 1 mg / mL), 1 mol / L hydrochloric acid 50 μL, 136 MBq [ ¹²⁵ I] iodine Sodium fluoride (40 μL in volume) and 10 μL of 10% (W / V) hydrogen peroxide were added. The mixture was allowed to stand at 50 ° C. for 10 minutes, and then subjected to HPLC under the same conditions as in Reference Example 6 to [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1, 2-a] The pyridine fraction was fractionated (FIG. 8, step 4).

A solution obtained by adding 10 mL of water to the fraction was applied to a reverse phase column (trade name: Sep-Pak (registered trademark, Waters Investments Limited) Light C18 Cartridges, manufactured by Waters, packing amount of filler: 130 mg). Then, [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine was adsorbed and collected on the column. The column was washed with 1 mL of water, and then 1 mL of ethanol was passed through to elute [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine. The amount of radioactivity obtained was 37.5 MBq immediately after synthesis. In addition, when measured by TLC analysis under the same conditions as in Reference Example 6, the radiochemical purity was 96.5%.

Reference Example 8 Synthesis of [ ¹²³ I] -IMPY

[ ¹²³ I] -IMPY was synthesized according to the following steps for use in Comparative Examples in the study on LogP _octanol and brain accumulation.

According to the method described in the literature (Zhi-Ping Zhuang et al., J. Med. Chem, 2003, 46, p.237-243), 6-tributylstannyl-2- [4 ′-(N, N-dimethylamino) ) Phenyl] imidazo [1,2-a] pyridine was synthesized and dissolved in methanol (concentration: 1 mg / mL). To 53 μL of the solution, 100 μL of 1 mol / L hydrochloric acid, 20 to 50 μL of [ ¹²³ I] sodium iodide in 1 to 240 MBq, 10 μL of 1 mmol / L sodium iodide solution, 10 μL of 10% (W / V) hydrogen peroxide were added. The mixture was allowed to stand at 50 ° C. for 10 minutes, and then subjected to HPLC under the same conditions as in Reference Example 4 to fractionate the [ ¹²³ I] -IMPY fraction.

A solution obtained by adding 10 mL of water to the fraction was passed through a reverse phase column (trade name: Sep-Pak (registered trademark) Light C18 Cartridges, manufactured by Waters, packing amount of filler: 130 mg), and [ ¹²³ I] -IMPY was adsorbed and collected on the column. After washing this column with 1 mL of water, 1 mL of ethanol was passed through to elute [ ¹²³ I] -IMPY. The amount of radioactivity obtained was 47-56 MBq immediately after synthesis. Moreover, when the TLC analysis was performed on the conditions similar to the reference example 4, the radiochemical purity was 98.0%.

Example 1 Synthesis of 6-methoxy-2- [4 '-(3 "-paratoluenesulfonyloxypropoxy) phenyl] imidazo [1,2-a] pyridine

100.0 g (corresponding to 0.575 mol) of 2-bromo-3-hydroxypyridine was dissolved in 310 mL of dimethyl sulfoxide, and 575 mL (corresponding to 0.575 mol) of a 1 mol / L sodium methoxide-methanol solution was added thereto. Was heated to 90 ° C. and methanol was distilled off. After cooling the reaction solution to 10 ° C. or lower, 93.9 g (corresponding to 0.662 mol) of methyl iodide was added, and the mixture was stirred at room temperature for 20.5 hours. After completion of the reaction, the reaction solution was poured into ice water and extracted twice with chloroform. The combined chloroform layers were washed with 1 mol / L sodium hydroxide, and then washed twice with saturated brine. This was dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure to obtain 65.4 g (0.348 mol) of 2-bromo-3-methoxypyridine (FIG. 1, step 1).

Concentrated sulfuric acid (262 mL) was cooled to −2 ° C., 90% nitric acid (262 mL) was carefully added thereto, and then 2-bromo-3-methoxypyridine (65.3 g, equivalent to 0.347 mmol) was carefully added. The resulting mixture was stirred in an ice bath for 10 minutes, then stirred at room temperature for 30 minutes, further heated to 55 ° C. and stirred for 1.5 hours. After cooling the reaction solution, it was gradually poured into ice to form a precipitate, which was collected by filtration and washed with water. The obtained precipitate was dried under reduced pressure in the presence of diphosphorus pentoxide to obtain 55.7 g (corresponding to 0.239 mmol) of 2-bromo-3-methoxy-6-nitropyridine (FIG. 1, step 2). .

25.6 g (corresponding to 0.239 mol) of 2-bromo-3-methoxy-6-nitropyridine was dissolved in 1700 mL of ethanol, 37.3 g of 10% palladium carbon (50% wet) was added under an argon stream, and then 1 water of hydrazine was added. 283 mL of Japanese product was added dropwise. The reaction mixture was heated to reflux for 70 minutes, the reaction solution was cooled to room temperature, palladium carbon was filtered, the filtrate was washed with ethanol, and the washing solution was combined with the filtrate. The solution was concentrated under reduced pressure, 1300 mL of water and 130 mL of concentrated aqueous ammonia were added, and the mixture was extracted 8 times with chloroform. The combined chloroform layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was distilled under reduced pressure to obtain 26.2 g (corresponding to 0.211 mol) of 2-amino-5-methoxypyridine (see FIG. 1, step 3).

50 mL of ethyl acetate was added to and suspended in 28.17 g (corresponding to 126 mmol) of cupric bromide, and 8.18 g (corresponding to 60.0 mmol) of 4'-hydroxyacetophenone was dissolved in a mixed solution of 50 mL of ethyl acetate and 50 mL of chloroform. The solution was added and heated to reflux. After 5 hours, the reaction solution was cooled to room temperature and filtered, and the filtrate was concentrated under reduced pressure. The residue was dissolved in ethyl acetate and decolorized by adding activated carbon, and then the solution was filtered and concentrated. The resulting crude product was purified by flash silica gel column chromatography (eluent: chloroform / methanol = 20/1), recrystallized from ethyl acetate-petroleum ether, and 2-bromo-4′-hydroxyacetophenone. 7.25 g (corresponding to 33.7 mmol) was obtained (FIG. 1, step 4).

2-Bromo-4′-hydroxyacetophenone 2.15 g (equivalent to 10.0 mmol) and 2-amino-5-methoxypyridine 1.25 g (equivalent to 10.0 mmol) were dissolved in 50 mL of acetonitrile and placed in a 90 ° C. oil bath. And heated to reflux for 3.5 hours. After completion of the reaction, the reaction solution was cooled to room temperature, and the precipitate was filtered off. The precipitate separated by filtration was washed with acetonitrile and dried under reduced pressure to obtain crude crystals. The obtained crude crystals were suspended in a mixed solution of 40 mL of water and 40 mL of methanol, about 20 mL of a saturated sodium hydrogen carbonate solution was added thereto, and the mixture was shaken with an ultrasonic cleaner for 5 minutes. The precipitate was filtered off, washed well with water, and dried under reduced pressure to give 1.96 g (equivalent to 8.16 mmol) of 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine. (FIG. 1, step 5).

1.45 mL (equivalent to 20.0 mmol) of 1,3-propanediol was dissolved in 200 mL of methylene chloride, and 6.96 g (equivalent to 30.0 mmol) of silver oxide and 666 mg of potassium iodide (equivalent to 4.0 mmol) were added thereto in an ice bath. And 4.21 g (equivalent to 22.0 mmol) of paratoluenesulfonyl chloride were added and stirred at room temperature for 3 hours. Insoluble matter was filtered from the reaction mixture, and the insoluble matter was further washed with ethyl acetate. The filtrate and washings were combined and concentrated, and the resulting crude product was purified by flash silica gel chromatography (eluent: hexane / ethyl acetate = 3/2 → 1/1) to give 1,3-propanediol. 2.47 g (corresponding to 10.7 mmol) of monoparatoluenesulfonate was obtained (FIG. 1, step 6).

To a solution of 554 mg of 1,3-propanediol monoparatoluenesulfonate (equivalent to 2.40 mmol) in 10 mL of tetrahydrofuran was added 260 mg (1.08 mmol) of 2- (4′-hydroxyphenyl) -6-methoxyimidazo [1,2-a] pyridine. Equivalent) and 636 mg (corresponding to 2.42 mmol) of triphenylphosphine were added, and 5 mL of N, N-dimethylformamide was further added to completely dissolve the contents. To the reaction mixture, 0.48 mL (equivalent to 2.42 mmol) of diisopropyl azodicarboxylate was added and stirred at room temperature for 23 hours, and then the reaction solution was concentrated. The obtained crude product was purified by flash silica gel column chromatography (eluent: chloroform / ethyl acetate = 19/1), and further recycled preparative HPLC (HPLC apparatus: LC-908 (product name, manufactured by Nippon Analytical Industries, Ltd.) ), Column: JAIGEL 2H (product name, manufactured by Nihon Analytical Industrial Co., Ltd.) was used in two, and purified using a mobile phase: chloroform, and then flash silica gel column chromatography (eluent: hexane / ethyl acetate = 35 / 65) to obtain 220 mg (corresponding to 0.487 mmol) of 2- [4 ′-(3 ″ -paratoluenesulfonyloxypropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine (FIG. 1, step 7).

The NMR measurement results (internal standard substance: tetramethylsilane) of the obtained compound were as follows.

NMR apparatus used: JNM-ECP-500 (manufactured by JEOL Ltd.)
¹ H-NMR (solvent: deuterated chloroform, resonance frequency: 500 MHz): δ7.81-7.77 (m, 2H), 7.76-7.72 (m, 2H), 7.71-7.70 (m, 1H), 7.64-7.62 (m , 1H), 7.49-7.46 (m, 2H), 7.24-7.21 (m, 2H), 6.95-6.92 (m, 1H), 6.81-6.77 (m, 2H), 4.25 (t, J = 6.0 Hz, 2H ), 3.95 (t, J = 6.0 Hz, 2H), 3.80 (s, 3H), 2.34 (s, 3H), 2.11 (quint., J = 6.0 Hz, 2H).

¹³ C-NMR (solvent: deuterated chloroform, resonance frequency: 125 MHz): δ 158.16, 149.11, 145.41, 144.77, 142.71, 132.64, 129.75, 127.71, 126.93, 126.85, 119.45, 117.28, 114.47, 108.35, 107.49, 66.99, 62.97, 56.11, 28.77, 21.52.

Example 2 Synthesis of 2- [4 ′-(3 ″-[ ¹⁸ F] fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine

[ ¹⁸ F] Fluoride ion-containing H ₂ ¹⁸ O (radioactivity 5087 MBq, correction value at the start of synthesis) was passed through Sep-Pak Light QMA (trade name, manufactured by Nippon Waters Co., Ltd.), and [ ¹⁸ F] Adsorbed and collected fluoride ions. Next, an aqueous solution of potassium carbonate (66.7 mmol / L, 0.3 mL) and Cryptofix 222 (trade name, manufactured by Merck & Co., Inc.) 20 mg (corresponding to 53.1 μmol) in 1.5 mL of acetonitrile were passed through the column, [ ¹⁸ F] fluoride ions were eluted.

This was heated to 100 ° C. under a flow of helium gas to evaporate water, and then acetonitrile (0.3 mL × 2) was added for azeotropic distillation to dryness. Here, 2- [4 ′-(3 ″ -paratoluenesulfonyloxypropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine 5 mg of N, N-dimethylformamide 1 synthesized in Example 1 above was used. 0.0 mL solution was added and heated for 10 minutes at 130 ° C. After the reaction solution was cooled to 30 ° C., 3.0 mL of diethyl ether was added to the reaction solution, and Sep-Pak Plus Silica (trade name, manufactured by Nihon Waters) was added. Further, a mixture of 3.5 mL of diethyl ether and 0.5 mL of N, N-dimethylformamide was passed twice through a Sep-Pak Plus Silica. Concentrate by heating to 60 ° C., and mix the acetonitrile / water / triethylamine = 550: 450: 1 with the concentrate. It was diluted by adding 2 mL.

The obtained solution was subjected to HPLC (column: SUMPAX ODS JP-06 (20 mm.d. × 250 mm, manufactured by Sumika Chemical Analysis Center), eluent: acetonitrile / water / triethylamine = 500/500/1, flow rate: 7.5 mL / Min) was used for purification. After diluting the fraction of the eluent containing the target product with 50 mL of water, this solution was passed through Sep-Pak Plus C18 (trade name, manufactured by Nihon Waters Co., Ltd.), and the target product was adsorbed and collected. Next, 20 mL of water was passed through the column for washing, and then 2 mL of ethanol was passed through and eluted to give 2- [4 ′-(3 ″-[ ¹⁸ F] fluoropropoxy) phenyl] -6-methoxyimidazo [ An ethanol solution of 1,2-a] pyridine was obtained, and the amount of radioactivity obtained was 1795 MBq (94 minutes after the start of synthesis), and TLC analysis was performed under the following conditions. 4%.

TLC analysis conditions:
TLC plate: Silica Gel 60 F ₂₅₄ (product name, manufactured by Merck)
Developing phase: chloroform / methanol / triethylamine = 50/1/2
Detector: Rita Star (product name, manufactured by raytest)

(Examples 3-5, Comparative Examples 1-5) Measurement of Amyloid Affinity The amyloid affinity of the compound of the present invention was evaluated by the following in vitro binding test.

(1) Aβ _1-40 (Peptide Institute) (hereinafter referred to as Aβ _1-40 ) was dissolved in a phosphate buffer (pH 7.4) and shaken at 37 ° C. for 62 to 72 hours. Aggregated Aβ suspension (hereinafter referred to as amyloid suspension in this example) was obtained.

(2) For the above amyloid suspension, fluorimetric measurement using thioflavin T (manufactured by Fluka) according to the method described in the literature (Naiki, H. et al., Laboratory Investigation. 74 , p.374-383 (1996)). A qualitative experiment was conducted to confirm that the aggregated Aβ obtained in (1) was amyloid (measurement conditions: excitation wavelength 446 nm, fluorescence wavelength 490 nm).

(3) In accordance with the method described in the literature (Wang, Y. et al., J. Labeled Compounds Radiopharmaceut. 44 , S239 (2001)), [ ¹²⁵ I] 2 with 2- (4′-aminophenyl) benzothiazole as a labeled precursor -(3'-iodo-4'-aminophenyl) benzothiazole (hereinafter referred to as [ ^125I ] 3'-I-BTA-0) was prepared and dissolved in ethanol. Congo Red, Thioflavin T and 6-Methyl-2- [4 ′-(N, N-dimethylamino) phenyl] benzothiazole (hereinafter 6-Me-BTA-2) are used by weighing commercially available reagents as they are. It was.

(4) 2- (3′-iodo-4′-aminophenyl) benzothiazole (hereinafter referred to as 3′-I-BTA-0) and IMPY were prepared according to the literature (Wang, Y. et al., J. Labeled Compounds Radiopharmaceut. 44 , S239 (2001)) and the literature (Zhuang, ZP et al., J. Med. Chem. 46 , 237 (2003)).

(5) Phosphate buffer solution containing 0.1% bovine serum albumin (pH 7.) so that the final concentrations of [ ¹²⁵ I] 3′-I-BTA-0, each evaluation compound and amyloid are as shown in Table 2. The sample dissolved in 4) was prepared and filled in each well (volume: about 0.3 mL) of a 96-well microplate.

(6) The microplate filled with the sample solution was shaken at 22 ° C. for 3 hours at a constant speed (400 rpm), and then each sample solution was glass fiber filter (trade name: Multiscreen ^™ -FC, manufactured by Millipore) ) Was separated from [ ¹²⁵ I] 3′-I-BTA-0 bound to amyloid and [ ¹²⁵ I] 3′-I-BTA-0 not bound.

(7) The glass fiber filter used for the filtration of each sample solution was washed (0.5 mL × 5 times) with a phosphate buffer solution (pH 7.4) containing 0.1% bovine serum albumin. Radioactivity was measured with an autowell gamma system (Aloka, model: ARC-301B), and used for calculating the inhibition rate as the amount of radioactivity of each sample solution (hereinafter, the radiation in the sample with each evaluation compound concentration of 0) The activity amount is A, and the radioactivity amount in a sample having an evaluation compound concentration of 0.001 nmol / L or more is B).

(8) Separately, a liquid containing 15 μmol / L of 6-Me-BTA-2, 400 pmol / L of [ ¹²⁵ I] 3′-I-BTA-0, and 1 μmol / L of Aβ _1-40 was prepared, The amount of radioactivity was measured by performing the same operations as in (6) and (7) above. The obtained radioactivity was used as the background radioactivity and used for calculation of the inhibition rate (hereinafter referred to as BG).

(9) Using the radioactivity measured in (7) and (8) above, the following formula (1):

The inhibition rate was obtained more. A graph was prepared by plotting the value obtained by probit conversion of the obtained inhibition rate against the logarithm of the concentration of the evaluation compound, and an approximate straight line was prepared by the method of least squares. Using this straight line, the concentration of each evaluation compound was determined so that the amount of radioactivity was half of the value in the sample without addition of each evaluation compound, and the 50% inhibitory concentration (hereinafter referred to as IC _50% value) of each compound was obtained. Using this value as an index, the affinity of each evaluation compound for amyloid (aggregated Aβ _1-40 ) was evaluated.

Table 3 shows the IC _50% value of each evaluation compound. Compounds 1 to 3 all showed an IC _50% value of less than 100, and had higher amyloid (aggregated Aβ _1-40 ) affinity than Congo Red and Thioflavin T. From this result, it was shown that the compounds 1 to 3 are compounds having good amyloid (aggregated Aβ _1-40 ) affinity. In particular, Compound 1 had higher amyloid (aggregated Aβ _1-40 ) affinity than IMPY, higher than 3′-I-BTA-0 and 6-Me-BTA-2.

(Example 6, Comparative Example 6) Measurement of partition coefficient using octanol extraction method

A partition coefficient (hereinafter referred to as _logPoctanol ) using an octanol extraction method generally known as an indicator of the blood-brain barrier (hereinafter referred to as BBB) permeability of the compound was measured.

10 mL of a solution containing Compound 4 (Example 5) and 2 mL of 10 mmol / L phosphate buffer (pH 7.4) were added to 2 mL of octanol and stirred for 30 seconds. This mixture is centrifuged (2000 rpm / min x 60 min) with a low-speed centrifuge (Hitachi Koki Co., Ltd., model: CENTRIFUGE CT4D), and 1 mL each of the octanol layer and the aqueous layer is collected and each radiation is radiated. The ability was measured with an autowell gamma system (manufactured by Aloka, model: ARC-301B). Using the obtained radioactivity, the logP _octanol value was calculated from the formula (2).

The results are shown in Table 4. For compounds that can penetrate the BBB, the logP _octanol value is known to be between 1 and 3 (Douglas D. Dischino et al., J. Nucl. Med., (1983), 24, p.1030-1038). The value of logP _octanol of Compound 4 was 1.8, suggesting that it had BBB permeability like IMPY of Comparative Example.

(Examples 7-9, Comparative Example 7) Measurement of partition coefficient using HPLC

The partition coefficient by HPLC (hereinafter referred to as logP _HPLC ) was measured by the following method. This logP _HPLC is a numerical value known to have an equivalent value at pH 7.2 to _7.4 with logP _octanol generally known as an index of BBB permeability of a compound (Franco Lombardo et al , J. Med. Chem., (2000), 43, p.2922-2927).

First, each evaluation compound shown in Table 5 was dissolved in methanol containing 10% dimethyl sulfoxide so as to have a concentration of 1 mg / mL to prepare a sample solution. 1 μL of this sample solution was subjected to HPLC analysis under the following conditions to determine the solvent elution time (t ₀ ) and the compound elution time (t _R ).

HPLC conditions:
Column: Prodigy ODS (3) (product name, manufactured by phenomenex, size: 4.6 × 250 mm)
Mobile phase: 50 mM triethylamine phosphate (pH 7.2) / acetonitrile = 40/60 mixed solution Flow rate: 0.7 mL / min Detector: UV-visible spectrophotometer (detection wavelength: 282 nm)

Using the obtained t ₀ and t _R , the retention factor (hereinafter referred to as K ′ _HPLC value) of each evaluation compound was determined from the calculation formula (3).

Separately, [ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine solution (radioactive concentration 37 MBq / mL) synthesized in Reference Example 6 above. ) And [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine solution (radioactive concentration 37 MBq / mL) synthesized in Reference Example 7 were separately prepared. 10 μL each was added to 2 mL of octanol prepared in 1), and 2 mL of 10 mmol / L phosphate buffer solution (pH 7.4) was further added to each solution. Centrifugation was performed for 60 minutes, and radioactivity was measured for each 1 mL of the octanol phase and the aqueous phase with an autowell gamma system (manufactured by Aloka, model: ARC-301B). It was. From the obtained radioactivity was calculated _{logP octanol} value using the above equation (2).

Furthermore, 2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine solution synthesized in Reference Example 4 and 2- (4) synthesized in Reference Example 5 were used. The 4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine solution was subjected to the same HPLC analysis as described above to determine the K ′ _HPLC value.

2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine and 2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine ^'[125 I] over 2- (4 relative _HPLC' log ₁₀ K in - (3 "- fluoro) phenyl-6-iodo-imidazo [1,2-a] pyridine and ^[125 I] over 2- ( on the plot of the _{logP octanol} values of 4'-hydroxyphenyl) -6-iodo-imidazo [1,2-a] pyridine was estimated slope and y-intercept of the straight line. using this _value, the _{logP octanol} value Assuming that the logP _HPLC value is equal at pH 7.2 to 7.4, the following equation (4) was obtained.

Using the K ′ _HPLC determined for each evaluation compound, the logP _HPLC value for each evaluation compound was determined according to the above formula (4).

The results are shown in Table 6. As shown in this table, the logP _HPLC value showed a value between 1 and 3 in any of compounds 1 to 3. As described above, it is known that a logP _octanol value is a value between 1 and 3 in a compound that can penetrate the BBB (Douglas D. Dischino et al., J. Nucl. Med., ( 1983), 24, p. 1030-1038). In addition, logP _octanol and logP _HPLC are known to have an equivalent value at pH 7.2 to 7.4 (Franco Lombardo et al., J. Med. Chem., (2000), 43, p. .2922-2927). From the above results, it was suggested that the compounds 1 to 3 have the property of permeating the BBB.

(Example 10, Comparative Example 8) Measurement of brain migration and clearance

Using Compound 4, the time course of radioactivity accumulation in the brain of male Wistar rats (7 weeks old) was measured.

A solution prepared by dissolving Compound 4 in a physiological saline containing 10 mg / mL ascorbic acid and [ ¹²³ I] -IMPY (Comparative Example 7) prepared in Reference Example 8 were dissolved in a physiological saline containing 10 mg / mL ascorbic acid. Each solution (radioactivity concentration 15-31MBq / mL) 0.05mL was administered to the said rat from the tail vein under thiopental anesthesia. Blood was collected from the abdominal aorta at 2 minutes, 5 minutes, 30 minutes, and 60 minutes after administration, and the brain was collected, and the radioactivity of the brain was measured using an autowell gamma system (form: ARC-301B, manufactured by Aloka). (Hereinafter referred to as A in this example), and the brain mass was further measured. Moreover, the radioactivity amount about 0.05 mL of the solution which diluted the administration liquid 1000 times was measured similarly (it is set as B in a present Example hereafter). Using these measurement results, the radioactivity distribution rate per unit weight (% ID / g) to the brain at each dissection time point was calculated from the following formula (5). The experiment was performed using three animals at each time point.

The results are shown in Table 7. As shown in Table 7, Compound 4 showed an accumulation equal to or higher than ¹²³ I-IMPY at 2 minutes after administration, and then showed a tendency to disappear rapidly over 60 minutes. From this result, it was suggested that the compound 4 has high brain transferability and rapid clearance from the brain, like ¹²³ I-IMPY.

(Example 11) Confirmation of depiction of amyloid in the brain

In order to evaluate whether the compound according to the present invention can depict amyloid in the brain, the following experiment was conducted.

(1) Aβ _1-42 (Wako Pure Chemical Industries) was dissolved in a phosphate buffer (pH 7.4) and shaken at 37 ° C. for 72 hours, and 1 mg / mL aggregated Aβ suspension (hereinafter, this example) To obtain an amyloid suspension).

(2) 2.5 μL (corresponding to 25 μg) of the amyloid suspension was injected into one side of the amygdala of a male Wistar rat (7 weeks old), and as a control, phosphate buffered saline (pH 7) .4) was injected at 2.5 μL. Rats three days after the injection of amyloid suspension and phosphate buffered saline (pH 7.4) were used as specimens.

(3) Compound 4 was dissolved in 10 mg / mL ascorbic acid-containing physiological saline to prepare a sample solution (radioactivity concentration 84 MBq / mL). This solution was administered to the rat through the tail vein (dose: 0.5 mL, dosed radioactivity: equivalent to 42 MBq).

(4) 30 minutes after administration, the brain was removed, and a brain section having a thickness of 10 μm was prepared using a microtome (format: CM3050S, manufactured by LEICA). The brain section was exposed on an imaging plate for 1.5 hours, and then image analysis was performed using a bioimaging analyzer (form: BAS-2500, manufactured by Fuji Photo Film Co., Ltd.).

(5) After completion of the above image analysis using a bioimaging analyzer, pathological staining with thioflavin T was performed and a fluorescence microscope (Nikon Corporation, model: TE2000-U type, excitation wavelength: 400 to 440 nm, detection wavelength: 470 nm) ) Was used to confirm that amyloid was deposited on the section (FIG. 9b).

FIG. 9 shows an image of autoradiogram and thioflavin T staining in a brain section of a rat injected with amyloid brain. As shown in this figure, in the amygdaloid nucleus on the side injected with the amyloid suspension, a good image having clear radioactivity accumulation and less non-specific accumulation at other sites was obtained. Moreover, from the result of thioflavin T staining at the site where radioactivity was accumulated, it was confirmed that amyloid was present at the site where accumulation was observed. On the other hand, no significant accumulation of radioactivity was confirmed in the amygdaloid nucleus on the side injected with phosphate buffered saline compared with other sites.
From these results, it was suggested that Compound 4 has the ability to accumulate in brain amyloid and has the ability to depict brain amyloid.

(Examples 12 to 14) Reverse mutation test

In order to examine the gene mutagenicity of compound 1, compound 2 and compound 3, a reverse mutation test (hereinafter referred to as Ames test) using TA98 and TA100 of Salmonella typhimurium was performed.

The test was conducted for the case of no addition of S9mix and the addition of S9mix. Negative subjects use dimethyl sulfoxide, positive subjects use 2- (2-furyl) -3- (5-nitro-2-furyl) acrylamide when S9mix is not added, and 2-aminoanthracene when S9mix is added. Using.

The amount of each sample added to the test plate was 1250 μg / plate for Compound 1 and 7 doses (common ratio 4), and 5000 μg / plate for Compound 2 and Compound 3 was the maximum dose. It was carried out at 7 doses (public ratio 3). The test substance and the test strain (TA98 or TA100), or the test substance, S9mix, and the test strain were mixed, then overlaid on the medium on the test plate using soft agar, and cultured at 37 ° C. for 48 hours. The determination was made by counting the number of back mutation colonies in the plate after culture, and the number of back mutation colonies showed a value more than twice that of the negative control, and the case where it increased further depending on the concentration was regarded as positive. .

The results are shown in Table 8. The number of revertant colonies in the treatment groups of Compound 1, Compound 2, and Compound 3 was less than twice that of the negative control regardless of whether S9mix was added or not in any strain. On the other hand, the positive control substance treatment group showed a clear increase in the number of revertant colonies. From the above results, Compound 1, Compound 2 and Compound 3 were determined to be Ames negative and determined to have no gene mutagenicity.

The compound according to the present invention can be used in the field of diagnostic agents.

Synthesis scheme of 6-methoxy-2- [4 '-(3 "-paratoluenesulfonyloxypropoxy) phenyl] imidazo [1,2-a] pyridine. Synthesis scheme of 2- [4 '-(3 "-fluoropropoxy) phenyl] -6-methoxyimidazo [1,2-a] pyridine (non-radioactive fluorinated product). Synthesis scheme of 2- [4 '-(3 "-fluoropropoxy) phenyl] -6-hydroxyimidazo [1,2-a] pyridine (non-radioactive fluorinated product). Synthesis scheme of 2- [4 '-(3 "-fluoropropoxy) phenyl] imidazo [1,2-a] pyridine (non-radioactive fluorinated product). Synthesis scheme of 2- (4 '-(3 "-fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine. Synthesis scheme of 2- (4'-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine. Synthesis scheme of [ ¹²⁵ I] -2- (4 ′-(3 ″ -fluoropropoxy) phenyl-6-iodoimidazo [1,2-a] pyridine. Synthesis scheme of [ ¹²⁵ I] -2- (4′-hydroxyphenyl) -6-iodoimidazo [1,2-a] pyridine. (A) Autoradiogram in a brain section 30 minutes after administration of Compound 4 and (b) Fluorescent microscopic image of thioflavin T-stained sample (enlarged display of amyloid suspension administration site.)

Claims (10)

Following formula (1):

(In the formula, R ¹ represents a hydroxyl group or a group selected from alkoxy substituent having 1 to 4 carbon atoms,
R ² is a radioactive halogen substituent,
m is an integer of 0-2. Or a salt thereof. The compound or a salt thereof according to claim 1, wherein R ² is selected from the group consisting of ¹⁸ F, ⁷⁶ Br, ¹²³ I, ¹²⁴ I, ¹²⁵ I or ¹³¹ I. The compound or a salt thereof according to claim 1 or 2, wherein R ² is ¹⁸ F. Following formula (2):

(Wherein, R ³ is a hydroxyl group or a group selected from alkoxy substituent having 1 to 4 carbon atoms,
R ⁴ is a group selected from a non-radioactive fluorine substituent, a methanesulfonic acid substituent, a trifluoromethanesulfonic acid substituent or an aromatic sulfonic acid substituent,
m is an integer of 0-2. Or a salt thereof. Following formula (1):

(In the formula, R ¹ represents a hydroxyl group or a group selected from alkoxy substituent having 1 to 4 carbon atoms,
R ² is a radioactive halogen substituent,
m is an integer of 0-2. ) A low toxicity Alzheimer's disease diagnostic agent comprising a compound represented by The diagnostic agent for low toxicity Alzheimer's disease according to claim 5, wherein R ² is selected from the group consisting of ¹⁸ F, ⁷⁶ Br, ¹²³ I, ¹²⁴ I, ¹²⁵ I or ¹³¹ I. The low toxicity Alzheimer's disease diagnostic agent according to claim 5 or 6, wherein R ² is ¹⁸ F. 4. In vivo imaging of amyloid deposition, comprising the compound represented by the formula (1) according to any one of claims 1 to 3 or a salt thereof, and a pharmaceutically acceptable carrier or excipient. Pharmaceutical composition. 請 Motomeko 1 to the compound represented by the formula (1) according to any one of 3 or a salt thereof as an active ingredient, in vivo imaging composition of amyloid deposition. A PET or SPECT imaging composition comprising as an active ingredient the compound represented by the formula (1) according to any one of claims 1 to 3 or a salt thereof.

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