JP2021116238A - New compounds and their use - Google Patents

Abstract

The present invention provides a compound for visualizing TRPA1 in vivo. The present invention provides a compound represented by the following formula (1) or (2), or a salt thereof. (In the formula, R1 and R2 are substituents having a radioisotope.) [Selected Figure] None

Description

The present invention relates to novel compounds and their use.

X-ray CT (Computed Tomography), MRI (Magnetic Resonance Imaging), and PET (Positron Emission Tomography) are common methods for non-invasive imaging of a living body. Among them, PET has attracted particular attention because of its good resolution, various drugs that can be used, and its ability to diagnose its function.

PET is a technique for taking a tomographic image using γ-rays emitted when a positron collides with an electron. Specifically, when a molecule labeled with a radionuclide that emits positrons (positrons) (so-called PET molecular probe) is administered in vivo and the positrons emitted during the decay of the radionuclide collide with nearby electrons, 511 KeV. Two γ-rays with the energy of are emitted in the direction of 180 degrees. By detecting this γ-ray, the position of the PET molecular probe in the living body and the amount of the substance thereof can be quantitatively investigated. Currently, PET is widely used as a molecular imaging technology for diagnosing diseases and promoting drug discovery research.

In the field of pain treatment, palliative care is the mainstream, and there is no curative treatment. Although there are subjective indicators for assessing pain relief, there are no more accurate objective indicators and surrogate markers, and assessment of pain relief is limited to qualitative methods such as interviews, inspections and palpation. There is. Diagnostic imaging is one of the means for objectively evaluating the pain-relieving effect, and in recent years, attempts have been made to use PET in particular for evaluating the pain-relieving effect. The reason is that the resolution of PET is good, the agents that can be used for PET are various, and the function can be diagnosed by PET. If PET can be used to evaluate the pain-relieving effect, it will be possible to significantly improve medical techniques involved in the diagnosis and / or treatment of pain for which there is no curative treatment.

TRPA1 (Transient Receptor Potential Ankyrin 1) is a type of TRP channel and is known as a nociceptor. One of its functions is a function as a pain receptor. Therefore, the development of a compound that specifically binds to TRPA1 is expected to lead to the development of an analgesic, and pharmaceutical companies are proceeding with the development of a compound that specifically binds to TRPA1. For example, Non-Patent Document 1 shows a compound that is an agonist of TRPA1, and Non-Patent Document 2 shows a compound that is an antagonist of TRPA1.

In addition, if TRPA1 in the living body can be visualized, it will be useful for elucidating the mechanism of pain and constructing a method for diagnosing pain. For example, if TRPA1 of nerve tissue can be visualized, it will be possible to develop a medical quantitative diagnostic method for pain (indexing of pain) and to stratify patients, which will contribute to the development of therapeutic agents. Therefore, the development of a technique for visualizing TRPA1 in a living body is required.

Junichiro Takaya, et.al., J.Am.Chem.Soc., 2015, 137, 15859-15864. Lisa Rooney, et.al., J.Med.Chem., 2014, 57, 5129-5140.

However, a technique for visualizing TRPA1 in a living body has not yet been established.

One aspect of the present invention is to provide a technique for visualizing TRPA1 in a living body.

As a result of diligent studies, the present inventors have found that TRPA1 can be visualized in vivo by labeling a compound that specifically binds to TRPA1 with a radioisotope and administering the compound to a living body. The present invention has been completed.

That is, the present invention includes the following configurations.

<1> A compound represented by the following formula (1) or formula (2), or a salt thereof:

(In formula (1), R ¹ is a substituent having a radioactive isotope.)

(In formula (2), R ² is a substituent having a radioactive isotope).

<2> R ¹ and R ² are independently a radioisotope of halogen, an alkyl group having a radioisotope, an alkyl group substituted with a radioisotope, an alkoxy group having a radioisotope, and The compound according to <1>, or a salt thereof, which is a substituent selected from the group consisting of an alkoxy group substituted with a radioisotope.

<3> A bioimaging agent containing the compound according to <1> or <2> or a salt thereof as an active ingredient.

<4> The bioimaging agent according to <3>, which is for imaging TRPA1.

<5> The bioimaging agent according to <3> or <4>, which is used for PET imaging or evaluation of a pathological condition that affects the expression level of TRPA1.

<6> A bioimaging kit comprising a compound represented by the following formula (1) or the general formula (2) or a salt thereof:

(In formula (1), R ¹ is a substituent having a radioactive isotope.)

(In formula (2), R ² is a substituent having a radioactive isotope).

According to one aspect of the present invention, it is possible to provide a technique for visualizing TRPA1 in a living body.

In the embodiment, a diagram showing a preparative HPLC chart of the compound represented by formula (1) having a ^{11 C} nucleus. In the embodiment, a diagram showing the analytical HPLC chart of the compound represented by formula (1) having a ^{11 C} nucleus. It is a graph which shows the result of the evaluation test of the agonist activity with respect to TRPA1 in an Example. In the embodiment, a diagram showing a preparative HPLC chart of the compound represented by formula (2) having a ^{11 C} nucleus. In the embodiment, a diagram showing the analytical HPLC chart of the compound represented by formula (2) having a ^{11 C} nucleus. It is an image of PET imaging (whole body of a rat) in an example. It is an image of PET imaging (rat head) in an example. It is an image of PET imaging (whole body of a rat) in an example. It is an image of PET imaging (rat head) in an example.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention can be variously modified within the scope of the claims, and the present invention also relates to embodiments and examples obtained by appropriately combining the technical means disclosed in different embodiments and examples. Included in the technical scope of. In addition, all of the documents described herein are incorporated herein by reference. In the present specification, when "AB" is described with respect to a numerical range, the description is intended to be "A or more and B or less".

[1. Compound or salt thereof]
The compound of the present embodiment, or a salt thereof, is a compound represented by the following formula (1) or formula (2) or a salt thereof:

(In formula (1), R ¹ is a substituent having a radioactive isotope.);

(In formula (2), R ² is a substituent having a radioactive isotope).

In the above formulas (1) and (2), R ¹ and R ² are independently each of a radioisotope of halogen, an alkyl group having a radioisotope, an alkyl group substituted with a radioisotope, and radioactivity. It is preferably a substituent selected from the group consisting of an alkoxy group having an isotope and an alkoxy group substituted with a radioisotope. With this configuration, the compound represented by the formula (1) or the formula (2) or a salt thereof can be easily synthesized.

When R ¹ and R ² are radioactive isotopes of halogen, the halogen is not particularly limited and may be fluorine, chlorine, bromine, iodine, astatine, or tennessine. Among the above halogens, fluorine is preferable from the viewpoint of facilitating the synthesis of the compound or its salt, realizing the compound or its salt having an appropriate length of half-life, and reducing the exposure of the patient. ..

When R ¹ and R ² are an alkyl group having a radioisotope or an alkyl group substituted with a radioisotope, the alkyl group is not particularly limited, but the synthesis of a compound or a salt thereof is easy. From the viewpoint of increasing the affinity between the compound or its salt and TRPA1, those having 20 or less carbon atoms are preferable, those having 10 or less carbon atoms are more preferable, and those having 5 or less carbon atoms are preferable. Some are more preferable, and those having 3 or less carbon atoms are more preferable. The alkyl group can be linear, branched or cyclic.

When R ¹ and R ² are an alkyl group having a radioisotope or an alkyl group substituted with a radioisotope, the radioisotope is a radioisotope of any atom (eg, carbon or halogen). Can be a body. When the radioisotope is a radioisotope of carbon, R ¹ and R ² may be an alkyl group having radioactive isotopes. On the other hand, if the radioisotope is a radioisotope of halogen, R ¹ and R ² may be an alkyl group substituted with a radioactive isotope.

For alkyl groups described above, if the radioisotope is a radioisotope of fluorine, R ¹ and R ² are each, independently, fluoromethyl group, fluoroethyl group, fluoropropyl group, or fluoro butyl group There may be. When the radioisotope is a radioisotope of carbon, R ¹ and R ² are each, independently, a methyl group, an ethyl group, a propyl group, or may be a butyl group. Details of the radioactive isotope will be described later.

When R ¹ and R ² are an alkoxy group having a radioisotope or an alkoxy group substituted with a radioisotope, the alkoxy group is not particularly limited, but a compound or a salt thereof can be easily synthesized. From the viewpoint of increasing the affinity between the compound or its salt and TRPA1, those having 20 or less carbon atoms are preferable, those having 10 or less carbon atoms are more preferable, and 5 or less carbon atoms are used. Those having 3 or less carbon atoms are more preferable, and those having 3 or less carbon atoms are more preferable. The alkoxy group can be linear, branched, or cyclic.

If R ¹ and R ² are an alkoxy group having a radioisotope or an alkoxy group substituted with a radioisotope, the radioisotope is a radioisotope of any atom (eg, carbon or halogen). Can be a body. If the radioisotope is a radioisotope of carbon, then R ¹ and R ² can be alkoxy groups with a radioisotope. On the other hand, if the radioisotope is a radioisotope of halogen, R ¹ and R ² may be an alkoxy group substituted with a radioactive isotope.

Regarding the above-mentioned alkoxy groups, when the radioisotope is a radioisotope of fluorine, R ¹ and R ² are independently fluoromethoxy group, fluoroethoxy group, fluoropropoxy group, or fluoroisobropoxy group, respectively. It may be. When the radioisotope is a radioisotope of carbon, R ¹ and R ² may independently be a methoxy group, an ethoxy group, a propoxy group, or an isobropoxy group, respectively. Details of the radioactive isotope will be described later.

As mentioned above, the R ¹ and / or the R ² can have a radioactive isotope of any atom. The radioisotope is not particularly limited, but a radioisotope having an appropriate half-life is preferable. Examples of such radioisotopes include carbon radioisotopes and fluorine radioisotopes, with ¹¹ C and ¹⁸ F being preferred.

^{Since 11} C (half-life: 20.4 minutes) has a short half-life, exposure to radiation when administered to patients can be minimized. ^{Since 18} F (half-life: 109.8 minutes) has ^{a longer half-life than 11} C, the patient's exposure to radiation is slightly increased, but the time from the synthesis of the compound having ^{18 F to its use.} You can get a margin. Since the compound according to this embodiment can not always be prepared for use in the place where it is used, the compound having ¹⁸ F is used in the place where the compound is used after being synthesized in a dedicated facility for synthesis or the like. It is excellent in that it can be ordered and used in.

With respect to the compound represented by the formula (1) or a salt thereof, the position of the carbon atom in the aromatic ring to which ^{R 1 is bonded is not particularly limited.} The carbon atom in the aromatic ring to which ^{R 1} is bonded is based on the position of the carbon in the aromatic ring to which the five-membered ring (specifically, the five-membered ring containing a nitrogen atom and a sulfur atom) is bonded. , It may be a carbon atom at the ortho position, a carbon atom at the meta position, or a carbon atom at the para position. From the viewpoint of facilitating the synthesis of the compound or a salt thereof ^{, the carbon atom in the aromatic ring to which R 1} is bonded is preferably a carbon atom at the para position.

The salt of the compound of the present embodiment may be any form of salt. As used herein, the term "salt" is intended to be a salt that is physiologically acceptable to be administered to a subject. Examples of salts include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, magnesium salt, etc.), ammonium salts, organic base salts (trimethylamine salt, triethylamine salt, pyridine salt, picolin salt, etc.) , Dicyclohexylamine salts, N, N'-dibenzylethylenediamine salts, etc.), organic acid salts (acetate, maleate, tartrate, methanesulfonate, benzenesulfonate, nitate, toluenesulfonate, tri) Fluoroacetate, etc.), inorganic acid salts (hydrochloride, hydrobromide, sulfate, phosphate, etc.), but are not limited thereto.

The compounds represented by the above formulas (1) and (2) and their salts are prepared by known methods (for example, "J. Nucl. Med., 1995, 36, 1275-1281", "J. Pharmacol. Sci." , 2003, 91, 105-112 "," Chem. Rec., 2014, 14, 516-541 "," J. Org. Chem., 2015, 80, 6250-6258 "," J. Med. Chem., 2012, 55, 2342-2352 "," ACS Chem. Neurosci, 2018, 9, 578-586 "," Org. Lett., 2014, 16, 3224-3227 ", or" Org. Lett., 2015, 17, It can be manufactured according to the method described in "5780-5783"). More specifically, it can be synthesized according to the method described in Examples described later. In the compounds represented by the above formulas (1) and (2) and salts thereof, a substituent having a radioisotope (specifically, R ¹ or R ² ) is introduced into a commercially available compound. Can also be manufactured by. As ^{a method for introducing R 1} into a commercially available compound and ^{a method for introducing R 2} into a commercially available compound, basically the same method can be adopted, for example, described in Examples. It is possible to adopt the method of.

[2. Bioimaging agent]
The bioimaging agent of the present embodiment contains the compound represented by the above-mentioned formula (1) or formula (2) or a salt thereof as an active ingredient. The bioimaging agent may contain any one or a plurality of the compounds represented by the above formula (1) or the formula (2) or salts thereof. Since the compound represented by the formula (1) or the formula (2) or a salt thereof has already been described, the description thereof will be omitted here.

As used herein, the term "bioimaging agent" refers to a "bioimaging agent" that, after being administered in vivo, fluoresces with light of a specific wavelength (for example, light in the near infrared region), and the distribution and / or intensity of the fluorescence. Intended to be a composition for obtaining images of cells and / or tissues of interest, etc., based on such.

The living body to which the bioimaging agent is administered is not particularly limited, and examples thereof include non-human mammals and humans. Examples of non-human mammals include primates (monkeys, apes, etc.), evening hooves (boars, wild boars, pigs, sheep, goats, etc.), odd-toed hooves (horses, etc.), rodents (mouses, rats, hamsters, etc.) , Squirrels, etc.), Artiodactyla (rabbits, etc.), Meat (dogs, cats, ferrets, etc.). The non-human mammals described above may be livestock or companion animals or may be wild animals.

The tissue from which the image is acquired is not particularly limited, and is, for example, the brain (for example, a specific area of the brain), the lung, the body surface (for example, the skin), a lymph node, a cerebrovascular, a neovascularization of a tumor, and a living body. Organizations and the like can be mentioned.

The cell from which the image is acquired is not particularly limited, and examples thereof include chondrocytes, osteoblasts, fibroblasts, epithelial cells, epithelial cells, adipocytes, hepatocytes, pancreatic cells, and muscle cells. ..

This bioimaging agent is excellent in imaging organs in a living body, for example, in imaging the brain (for example, a specific area of the brain), lungs, and the body surface (for example, skin).

Specifically, when the bioimaging agent of the present embodiment contains the compound represented by the above formula (1) or a salt thereof as an active ingredient, the bioimaging agent comprises the brain (for example, brain identification). Area) and is excellent in lung imaging. Therefore, the bioimaging agent is preferably used for brain or lung imaging (in other words, imaging of TRPA1 present in the brain or lungs).

On the other hand, when the bioimaging agent of the present embodiment contains the compound represented by the above formula (2) or a salt thereof as an active ingredient, the bioimaging agent is used in the brain (for example, a specific region of the brain). ) And the imaging of the body surface (eg, skin). Therefore, the bioimaging agent is preferably used for imaging the brain or body surface (in other words, imaging TRPA1 present on the brain or body surface).

As shown in Examples described later, the compound represented by the formula (1) or a salt thereof has a difference in the degree of accumulation depending on the site in the brain as compared with the compound represented by the formula (2) or a salt thereof. big. Therefore, from the viewpoint of imaging while distinguishing a specific region in the brain from other regions in the brain, the compound represented by the formula (1) or a salt thereof is preferable.

The bioimaging agent of the present embodiment can be used for the purpose of imaging TRPA1, more specifically, for the purpose of quantitatively imaging TRPA1. Therefore, the bioimaging agent according to the present embodiment can quantitatively diagnose the severity of the pathological condition described later.

TRPA1 is known to be expressed in peripheral nerve cells, lungs, inner ears, intestinal tract, cutaneous keratinocytes, vascular endothelial cells, pancreatic β cells, and brain astrocytes. That is, the bioimaging agent of the present embodiment can be used for evaluating a pathological condition that affects the expression level of TRPA1 (in other words, has a correlation with the expression level of TRPA1).
For example, pain, cancer, arthritis degenerative arthritis, postherpetic nerve pain, lung disease (eg, tuberculosis, cough attack, and bronchial asthma), inflammatory bowel disease, irritable bowel syndrome, diabetic neuropathy, anticancer agents It enables diagnostic evaluation of induced peripheral neuropathy and abnormalities of the pancreas and cerebral nervous system. However, it is not limited to these pathological conditions and can be applied to the diagnostic evaluation of all life functions related to TRPA1. The cancers include all solid cancers and hematological malignancies. Examples of the cancer include severely painful cancers such as osteosarcoma and cancers that have metastasized to bone.

PET is preferable as a method for evaluating the above pathological condition, but the method is not limited to this, and for example, SPECT (Single photon emission computed tomography) may be used. When the compound or salt used is ¹³ C-labeled, the amount of metabolites analyzed by LC-MS (Liquid chromatography-mass spectrometry) is analyzed, and the compound or salt used is ¹⁴ C-labeled. If this is the case, analysis of the amount of metabolites by AMS (Accelerator mass spectrometry) can be used as a method for evaluating the pathological condition.

The bioimaging agent of this embodiment can be used for PET imaging. When a bioimaging agent is used in PET, the dose of the imaging agent to the subject may be very small, so that the subject has a pharmacological effect (pain relief, sensation of burns, etc.) due to activation or inhibition of TRPA1. It does not appear and is safe. Further, with the imaging agent according to the present embodiment, exposure to radioactive isotopes can be minimized.

The bioimaging agent may contain a component different from the above-mentioned active ingredient.

Ingredients different from active ingredients include buffers, pH regulators, preservatives, antioxidants, isotonic agents, high molecular weight polymers, excipients, lubricants, binders, disintegrants, carriers, diluents. , Solvents, solubilizers, stabilizers, fillers, solvents, solubilizers, suspending agents, isotonic agents, soothing agents and surfactants.

Examples of the above buffers include phosphate, phosphate, borate, borate, citric acid, citrate, acetate, acetate, carbonate, carbonate, tartaric acid, tartaric acid, ε-aminocaproic acid, and Examples include torometamol. Examples of the phosphate include sodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate and the like. Examples of the borate include borax, sodium borate, potassium borate and the like. Examples of the citrate include sodium citrate, disodium citrate, trisodium citrate and the like. Examples of the acetate include sodium acetate, potassium acetate and the like. Examples of the carbonate include sodium carbonate and sodium hydrogen carbonate. Examples of the tartrate salt include sodium tartrate and potassium tartrate.

Examples of the pH adjuster include hydrochloric acid, phosphoric acid, citric acid, acetic acid, sodium hydroxide, potassium hydroxide and the like.

Examples of the above isotonic agents include ionic isotonic agents (sodium chloride, potassium chloride, calcium chloride, magnesium chloride, etc.) and nonionic isotonic agents (glycerin, propylene glycol, sorbitol, etc.). And mannitol, etc.).

Examples of the preservatives include benzalkonium chloride, benzalkonium bromide, benzethonium chloride, sorbic acid, potassium sorbate, methyl paraoxybenzoate, propyl paraoxybenzoate, and chlorobutanol.

Examples of the above-mentioned antioxidants include ascorbic acid, tocophenol, dibutylhydroxytoluene, butylhydroxyanisole, sodium erythorbate, propyl gallate, and sodium sulfite.

Examples of the excipients include, but are not limited to, lactose, sucrose, D-mannitol, xylitol, sorbitol, erythritol, starch and crystalline cellulose.

Examples of the lubricant include, but are not limited to, magnesium stearate, calcium stearate, wax, talc and colloidal silica.

Examples of the binder include, but are not limited to, pregelatinized starch, methyl cellulose, crystalline cellulose, sucrose, D-mannitol, trehalose, dextrin, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and polyvinylpyrrolidone.

Examples of the disintegrant include, but are not limited to, starch, carboxymethyl cellulose, low degree of substitution hydroxypropyl cellulose, carboxymethyl cellulose calcium, croscarmellose sodium and sodium carboxymethyl starch.

Examples of the solvent include, but are not limited to, water for injection, alcohol, propylene glycol, macrogol, sesame oil, corn oil and tricapriline.

Examples of the solubilizing agent include polyethylene glycol, propylene glycol, D-mannitol, trehalose, benzyl benzoate, ethanol, trisaminomethane, cholesterol, triethanolamine, sodium carbonate and sodium citrate. Not limited to these.

Examples of the above suspending agents include, for example, surfactants (eg, stearyltriethanolamine, sodium lauryl sulfate, laurylaminopropionic acid, lecithin, benzalkonium chloride, benzethonium chloride, glycerin monostearate) and highly hydrophilic. The molecules (eg, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulosenarium, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose) are not limited thereto.

Examples of the tonicity agent include, but are not limited to, sodium chloride, glycerin and D-mannitol.

Examples of the above high molecular weight polymer include methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose acetate succinate, and hydroxypropyl methyl cellulose phthalate. , Carboxymethyl ethyl cellulose, cellulose phthalate acetate, polyvinylpyrrolidone, polyvinyl alcohol, carboxyvinyl polymer, polyethylene glycol, atelocollagen and the like.

The amount of the active ingredient contained in the bioimaging agent is not particularly limited, and may be, for example, 0.001% by weight to 100% by weight, 0.01% by weight to 100% by weight, based on the imaging agent. It may be 0.1% by weight to 100% by weight, 0.1% by weight to 95% by weight, or 0.1% by weight to 90% by weight. , 0.1% by weight to 80% by weight, 0.1% by weight to 70% by weight, 0.1% by weight to 60% by weight, 0.1% by weight. % To 50% by weight, 0.1% to 40% by weight, 0.1% to 30% by weight, 0.1% to 20% by weight. It may be 0.1% by weight to 10% by weight.

The amount of the component different from the active component contained in the bioimaging agent is not particularly limited, and may be, for example, 0% by weight to 99.999% by weight, or 0% by weight to 99% by weight, based on the imaging agent. It may be .99% by weight, 0% by weight to 99.9% by weight, 5% by weight to 99.9% by weight, or 10% by weight to 99.9% by weight. It may be 20% by weight to 99.9% by weight, 30% by weight to 99.9% by weight, 40% by weight to 99.9% by weight, and may be. It may be 50% by weight to 99.9% by weight, 60% by weight to 99.9% by weight, 70% by weight to 99.9% by weight, 80% by weight to 99% by weight. It may be 9.9% by weight, or 90% by weight to 99.9% by weight.

The method of administering the bioimaging agent is not particularly limited. Specifically, examples of the administration method include injection administration (for example, intravenous administration and transarterial administration), oral administration, nasal administration, oral mucosal administration, and transdermal administration. Therefore, the bioimaging agent of the present embodiment may be an injection, an internal medicine, a nasal medicine, or an external medicine. The bioimaging agent may be prepared as a liquid preparation of either a solution or a suspension, or as a solid preparation suitable for dissolving or suspending in a liquid (for example, a buffer solution). May be good.

The wavelength of the light irradiated to the living body in order to detect the bioimaging agent introduced into the living body is not particularly limited, but is preferably light in the near infrared region from the viewpoint of increasing the absorbance. , 700 nm to 2000 nm near-infrared light, 800 nm to 1500 nm near-infrared light, 900 nm to 1500 nm near-infrared light, more preferably 1000 nm to 1500 nm near-infrared light. Infrared light is more preferable.

[3. Bioimaging Kit]
The bioimaging kit of the present embodiment includes the compounds represented by the above formulas (1) and (2), or salts thereof. In addition, the above [1. Compound or salt thereof] and [2. The configuration described in [Bioimaging Agent] will be omitted here.

The bioimaging kit of the present embodiment, R ¹ in the formula ^(1), and, R ² in the formula (2) are each, independently, an alkyl group having radioisotope halogen, the radioactive isotope , A substituent selected from the group consisting of an alkyl group substituted with a radioisotope, an alkoxy group having a radioisotope, and an alkoxy group substituted with a radioisotope.

The bioimaging kit of this embodiment can be a kit for imaging TRPA1. Also, the bioimaging kit of this embodiment can be a kit for imaging the brain (eg, a specific region of the brain), lungs, and / or body surface (eg, skin).

The bioimaging kit of the present embodiment may have a configuration other than the compounds represented by the above formulas (1) and (2) or salts thereof. The composition includes, for example, a buffer, a pH adjuster, an antiseptic, an antioxidant, an isotonic agent, a high molecular weight polymer, an excipient, a lubricant, a binder, a disintegrant, a carrier, a diluent, and the like. Examples thereof include solvents, solubilizers, stabilizers, fillers, solvents, solubilizers, suspending agents, tonicity agents, soothing agents and surfactants. According to this configuration, the bioimaging agent described above can be easily prepared.

Further, as the above configuration, a syringe can be mentioned. In this case, the bioimaging agent can be easily administered to the subject by using the bioimaging kit of the present embodiment.

[4. others〕
One embodiment of the present invention can also be configured as follows.
<1> A bioimaging agent containing a compound represented by the formula (1) or the formula (2) or a salt thereof as an active ingredient is used as a subject (for example, mammal, non-human mammal, primate, even-toed ungera, odd-toed ungera). A bioimaging method comprising the step of administering to hoofs, rodents, artiodactyla, or carnivores).
<2> R ¹ and R ² of the above compounds are independently a radioisotope of halogen, an alkyl group having a radioisotope, an alkyl group substituted with a radioisotope, and an alkoxy group having a radioisotope. The bioimaging method according to <1>, which is a substituent selected from the group consisting of an alkoxy group substituted with a radioisotope.
<3> The bioimaging method according to <1> or <2> for imaging TRPA1.

One embodiment of the present invention can also be described as follows.
<4> Use of a compound represented by the formula (1) or the formula (2) for the production of a bioimaging agent, or a salt thereof.
<5> R ¹ and R ² of the above compounds are independently each of a radioisotope of halogen, an alkyl group having a radioisotope, an alkyl group substituted with a radioisotope, and an alkoxy group having a radioisotope. And the use according to <4>, which is a substituent selected from the group consisting of alkoxy groups substituted with radioisotopes.
<6> The method according to <4> or <5>, wherein the bioimaging agent is for imaging TRPA1.

[1: Precursor of compound represented by formula (1) (phenol precursor)]
The outline of the method for synthesizing the precursor (phenol precursor) of the compound represented by the formula (1) is shown below. The details of each synthesis step will also be described later.

1. 1. Synthesis of Compound 1-2a In a DMF solution (25.0 mL) containing 4-amino (2-amino-thiazole-4-yl) -phenol (960.5 mg, 5.0 mmol), imidazole (679.5 mg, 10. 0 mmol) was added, and a DMF solution (25.0 mL) containing TBSCl (983.8 mg, 6.5 mmol) was added dropwise under an ice bath, after which the mixture was stirred at room temperature for 3 days. Water was added to the mixture after the reaction was completed, the mixture was extracted with ethyl acetate, the obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the white solid compound 1-2a (1.4 g, 4.4 mmol, 78) was purified as shown below. %) Was obtained.

The identification results of Compound 1-2a performed using NMR are shown below.
^{1 1} H NMR (400 MHz, CDCl ₃ )
δ = 7.64 (dt, J = 9.1Hz, 2.5Hz, 2H), 6.84 (dt, J = 9.1Hz, 2.7Hz, 2H), 6.59 (s, 1H), 4 .92 (s, 2H), 0.99 (s, 9H), 0.20 (s, 6H).

2. Synthesis of Compound 1-3a In Compound 1-2a (154.0 mg, 0.5 mmol), HCTU (O- (6-Chloro-1H-benzotriazol-1-yl) -N, N, N', N'-tetramethyluronium After adding hexafluorophosphate (290.7 mg, 0.7 mmol), DIPEA (125.0 μL, 0.7 mmol), and 3-methoxypropionic acid (66.0 μL, 0.7 mmol), the mixture was added to dichloromethane (4. It was dissolved in 0 mL) and stirred at room temperature for 18 hours. Water was added to the mixture after the reaction was completed, the mixture was extracted with ethyl acetate, the obtained organic layer was washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine, and the organic layer was dried with sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the white solid compound 1-3a (188.9 mg, 0.5 mmol, 96) was purified as shown below. %) Was obtained.

The identification results of Compound 1-3a performed by NMR are shown below.
^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 9.78 (s, 1H), 7.70 (dt, J = 9.2 Hz, 2.4 Hz, 2H), 6.99 (s, 1H), 6. 87 (dt, J = 8.9Hz, 2.3Hz, 2H), 3.74 (t, J = 5.4Hz, 2H), 3.48 (s, 3H), 2.74 (t, J = 5) .6Hz, 2H), 0.99 (s, 9H), 0.21 (s, 6H).

3. 3. Synthesis of Compound 1-4a A THF solution (5.) Containing Compound 1-3a (193.7 mg, 0.5 mmol) in _{a BH 3 compound (0.9 M THF solution, 0.8 mL) under an argon atmosphere and in an ice bath.} 0 mL) was added and the mixture was stirred at 75 ° C. for 20 hours. After allowing to cool, water was added to the mixture after the reaction was completed, the mixture was extracted with ethyl acetate, the obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the white solid compound 1-4a (126.2 mg, 0.3 mmol, 68) was purified as shown below. %) Was obtained.

The results of NMR identification of Compound 1-4a are shown below.
^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.66 (dt, J = 9.2 Hz, 2.6 Hz, 2H), 6.83 (dt, J = 8.9 Hz, 2.3 Hz, 2H), 6 .55 (s, 1H), 5.67 (s, 1H), 3.53 (t, J = 5.8Hz, 2H), 3.41 (q, J = 5.5Hz, 2H), 3.36 (S, 3H), 1.94 (quin, J = 6.2Hz, 2H), 0.98 (s, 9H), 0.19 (s, 6H).

4. Synthesis of Compound 1-5a Triethylamine (62.0 μL, 0.4 mmol) was added to an ethyl acetate solution (1.0 mL) containing Compound 1-4a (126.2 mg, 0.3 mmol), and further, under an ice bath. Chloroacetyl chloride (35.0 μL, 0.4 mmol) was added. The mixture was then stirred at room temperature for 16 hours. Water was added to the mixture after the reaction was completed, the mixture was extracted with ethyl acetate, the obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the white solid compound 1-5a (120.0 mg, 0.3 mmol, 79) was purified as shown below. %) Was obtained.

The results of NMR identification of compound 1-5a are shown below.
^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.75 (d, J = 8.8 Hz, 2H), 7.10 (s, 1H), 6.88 (dt, J = 9.0 Hz, 2.4 Hz) , 2H), 4.54 (s, 2H), 4.39 (s, 2H), 3.44 (t, J = 5.4Hz, 2H), 3.36 (s, 3H), 2.20 ( s, 2H), 1.00 (s, 9H), 0.22 (s, 6H).

5. Compound Synthesis Compound 1-5a (201.6mg, 0.4mmol) in 1-6a THF / _{H 2} O solution containing: a (2 1,3.0mL), acetic acid (52.0μL, 0.9mmol) was added Further, 1 M TBAF THF solution (0.5 mL, 0.5 mmol) was added under an ice bath. Then, the mixture was stirred at the same temperature for 3 hours. Water was added to the mixture after the reaction was completed, the mixture was extracted with ethyl acetate, the obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the purified product was washed with chloroform, and the white solid compound 1-6a was washed as shown below. (85.6 mg, 0.3 mmol, 57%) was obtained.

The results of NMR identification of compound 1-6a are shown below.
^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.77 (d, J = 8.6 Hz, 2H), 7.09 (s, 1H), 6.88 (dt, J = 9.4 Hz, 2.6 Hz) , 2H), 4.87 (s, 1H), 4.54 (s, 2H), 4.39 (s, 2H), 3.44 (t, J = 5.6Hz, 2H), 3.36 ( s, 3H), 2.19 (s, 2H).

[2: Compound represented by formula (1)]
The outline of the method for synthesizing the compound represented by the formula (1) is shown below. The details of each synthesis step will also be described later.

As Compound 1-2b, a commercially available product was used (trade name 2-amino-4- (4-fluorophenyl) -1,3-thiazole, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.).

1. 1. Synthesis of Compound 1-2c and Compound 1-2d 4-Amino (2-amino-thiazole-4-yl) -phenol (480.7 mg, 2.5 mmol) and K ₂ CO ₃ (521.1 mg, 3. DMF (10.0 mL) was added to the mixture with 8 mmol), and 2-fluoroethyltosylate (512.0 μL, 3.0 mmol) was further added. The mixture was then stirred at 50 ° C. for 24 hours. After allowing the mixture to cool, water is added to the mixture, the mixture is extracted with ethyl acetate, the obtained organic layer is washed with 1M aqueous NaOH solution and saturated brine, and the organic layer is washed with sodium sulfate. It was dry. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (n-hexane / ethyl acetate), and the purified product was washed with ethyl acetate. 280.6 mg, 1.2 mmol, 47%) was obtained.

Further, by performing the same operation using 4-amino (2-amino-thiazole-4-yl) -phenol and 3-fluoropropyltosylate, as shown below, the yellow powder compound 1-2d ( 103.7 mg, 0.4 mmol, 41%) was obtained.

The results of NMR identification of Compound 1-2c and Compound 1-2d are shown below.

Compound 1-2c

^１Ｈ ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３）δ＝７．７３(ｄｔ，Ｊ＝８．８Ｈｚ，２．５Ｈｚ，２Ｈ)、６．９４（ｄｔ，Ｊ＝９．２Ｈｚ，２．７Ｈｚ，２Ｈ）、６．６１（ｓ，１Ｈ）、４．９１（ｓ，２Ｈ）、４．８３（ｔ，Ｊ＝４．４Ｈｚ，１Ｈ）、４.７１（ｔ，Ｊ＝４．２Ｈｚ，１Ｈ）、４．２８（ｔ，Ｊ＝４．２Ｈｚ，１Ｈ）、４．２１（ｔ，Ｊ＝４．４Ｈｚ，１Ｈ）。

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.73 (dt, J = 8.8 Hz, 2.5 Hz, 2H), 6.94 (dt, J = 9.2 Hz, 2.7 Hz, 2H), 6 .61 (s, 1H), 4.91 (s, 2H), 4.83 (t, J = 4.4Hz, 1H), 4.71 (t, J = 4.2Hz, 1H), 4.28 (T, J = 4.2 Hz, 1H) 4.21 (t, J = 4.4 Hz, 1H).

Compound 1-2d

^１Ｈ ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３）δ＝７．７１（ｄｔ，Ｊ＝１２．０Ｈｚ，２．８Ｈｚ，２Ｈ）、６．９１（ｄｔ，Ｊ＝９．２Ｈｚ，２．８Ｈｚ，２Ｈ）、６．５９（ｓ，１Ｈ）、４．９９（ｓ，２Ｈ）、４．６６（ｄｔ，Ｊ＝４７．２Ｈｚ、５．６Ｈｚ，２Ｈ）、４．１２（ｔ，Ｊ＝６．０Ｈｚ，２Ｈ）、２．１８（ｄｑｕｉｎ、Ｊ＝２６．８Ｈｚ，６．０Ｈｚ，２Ｈ）。

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.71 (dt, J = 12.0 Hz, 2.8 Hz, 2H), 6.91 (dt, J = 9.2 Hz, 2.8 Hz, 2H), 6 .59 (s, 1H), 4.99 (s, 2H), 4.66 (dt, J = 47.2Hz, 5.6Hz, 2H), 4.12 (t, J = 6.0Hz, 2H) , 2.18 (dquin, J = 26.8 Hz, 6.0 Hz, 2H).

2. Synthesis of Compounds 1-3b to 6b, Compounds 1-3c to 6c, Compounds 1-3d to 6d For the synthesis of Compounds 1-3b to 6b, Compounds 1-3c to 6c, and Compounds 1-3d to 6d, compounds. It was synthesized by the same method as 1-3a to 6a. Details of the synthesis method are omitted, and the identification results of each substance by NMR are shown below.

Compound 1-3b (white crystals, 97% yield)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 9.84 (s, 1H), 7.83-7.79 (m, 2H), 7.09 (tt, J = 9.0 Hz, 2.0 Hz, 2H) ), 7.06 (s, 1H), 3.75 (t, J = 5.6Hz, 2H), 3.49 (s, 3H), 2.74 (t, J = 5.6Hz, 2H).

Compound 1-3c (white powder)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 10.11 (s, 1H), 7.77 (dt, J = 8.8 Hz, 2.5 Hz, 2H), 7.01 (s, 1H), 6. 96 (dt, J = 8.8Hz, 2.5Hz, 2H), 4.83 (t, J = 4.2Hz, 1H), 4.72 (t, J = 4.0Hz, 1H), 4.28 (T, J = 4.4Hz, 1H), 4.21 (t, J = 4.2Hz, 1H), 3.70 (t, J = 5.8Hz, 2H), 3.44 (s, 3H) 2.66 (t, J = 5.8Hz, 2H).

Compound 1-3d (yellow solid, 57% yield)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 9.80 (s, 1H), 7.77 (d, J = 8.8 Hz, 2H), 7.00 (s, 1H), 6.94 (d, J = 8.8Hz, 2H), 4.73 (t, J = 5.8Hz, 1H), 4.61 (t, J = 5.8Hz, 1H), 4.14 (t, J = 6.2Hz) , 2H), 3.74 (t, J = 5.6Hz, 2H), 3.49 (s, 3H), 2.74 (t, J = 5.4Hz, 2H), 2.23 (quin, J) = 6.2 Hz, 1H), 2.16 (quin, J = 5.9 Hz, 1H).

Compound 1-4b
Since it was not possible to isolate compound 1-4b and impurities, a mixture of compound 1-4b and impurities was used as compound 1-4b in the next reaction.

Compound 1-4c (30% yield (2steps))

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.73 (dt, J = 9.2 Hz, 2.4 Hz, 2H), 6.93 (dt, J = 9.4 Hz, 2.6 Hz, 2H), 6 .56 (s, 1H), 5.58 (s, 1H), 4.82 (t, J = 4.4Hz, 1H), 4.70 (t, J = 4.2Hz, 1H), 4.27 (T, J = 4.0Hz, 1H), 4.20 (t, J = 4.2Hz, 1H), 3.53 (t, J = 5.8Hz, 2H), 3.39 (q, J = 7.9Hz, 2H), 3.35 (s, 3H), 1.93 (quin, J = 6.1Hz, 2H).

Compound 1-4d (54% yield)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.72 (dt, J = 9.4 Hz, 2.6 Hz, 2H), 6.90 (dt, J = 9.4 Hz, 2.6 Hz, 2H), 6 .50 (s, 1H), 5.68 (s, 1H), 4.71 (t, J = 6.0Hz, 1H), 4.60 (t, J = 6.0Hz, 1H), 4.11 (T, J = 6.2Hz, 2H), 3.51 (t, J = 5.8Hz, 2H), 3.40 (q, J = 6.1Hz, 2H), 3.35 (s, 3H) , 2.21 (quin, J = 6.0Hz, 1H), 2.14 (quin, J = 6.1Hz, 1H), 1.92 (quin, J = 6.0Hz, 2H).

Compound 1-6b (white solid, 35% yield (2 steps))

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.87-7.83 (m, 2H), 7.17 (s, 1H), 7.10 (t, J = 9.0 Hz, 2H), 4. 54 (s, 2H), 4.39 (s, 2H), 3.44 (t, J = 5.8Hz, 2H), 3.37 (s, 3H), 2.19 (s, 2H).

Compound 1-6c (white solid, 94% yield)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.82 (d, J = 8.8 Hz, 2H), 7.10 (s, 1H), 6.97 (d, J = 8.8 Hz, 2H), 4.83 (t, J = 4.2Hz, 1H), 4.73 (t, J = 4.4Hz, 1H), 4.50 (s, 2H), 4.40 (s, 2H), 4. 30 (d, J = 4.4Hz, 1H), 4.23 (t, J = 4.2Hz, 1H), 3.44 (t, J = 5.8Hz, 2H), 3.36 (s, 3H) ), 2.20 (s, 2H).

Compound 1-6d (white solid, 37% yield)

^{1 1} H NMR (400 MHz, CDCl ₃ ) δ = 7.80 (d, J = 8.8 Hz, 2H), 7.10 (s, 1H), 6.95 (dt, J = 9.4 Hz, 2.6 Hz) , 2H), 4.73 (t, J = 5.8Hz, 1H), 4.61 (t, J = 6.0Hz, 1H), 4.54 (s, 2H), 4.40 (s, 2H) ), 4.14 (t, J = 6.2Hz, 2H), 3.44 (t, J = 5.8Hz, 2H), 3.36 (s, 3H), 2.23 (quin, J = 6) .1Hz, 2H), 2.16 (quin, J = 6.0Hz, 2H).

^[3:11 with a C nuclei, the compound represented by the formula (1)]
¹¹ C nuclei, using Sumitomo Heavy Industries Ltd. cyclotron CYPRIS HM-12S, manufactured by 14N (p, ^{α) 11} C nuclear reaction (current 5 .mu.A, irradiation time 52 min) of. [ ¹¹ C] Methyl iodide is prepared in the first reaction vessel ^{using 11} CO ₂ gas as a starting material using a dedicated labeling synthesizer (manufactured by Sumitomo Heavy Industries, Ltd.) ¹¹ CO ₂ → ¹¹ CH ₃ OH → ¹¹ CH ₃ I was converted in this order and synthesized.

The synthesized ¹¹ CH ₃ I was converted to ¹¹ CH ₃ OTf by passing it through AgOTf heated to 200 ° C. Phenol precursor (1.36 mg, 4.0 μmol), 1M NaOH (5.0 μL, 5.0 μmol) and acetone (400 μL) were prepared in advance in the second reaction vessel, and ¹¹ CH synthesized therein was prepared. ₃ OTf was transferred. Subsequently, the temperature in the second reaction vessel was brought to room temperature, and the mixture in the second reaction vessel was reacted for 1 minute.

After the reaction, the above mixture was purified by HPLC. FIG. 1 shows a preparative HPLC chart of a compound represented by the formula (1) having ^{11 C nuclei.} The preparative conditions by HPLC are: column: COSMOSIL 5-C ₁₈ AR-II 10 × 20 mm, 10 × 250 mm, developing solvent: CH ₃ CN: H ₂ O = 55: 45, flow rate: 6.0 mL / min, retention time. : 16.1 min, detection: UV 254 nm, RI. Further, FIG. 2 shows an analytical HPLC chart of the compound represented by the formula (1) having ^{11 C nuclei.} The analysis conditions by HPLC were as follows: column: COSMOSIL 5-C ₁₈ MS-II 4.6 × 150 mm, developing solvent: CH ₃ CN: H ₂ O = 60: 40, flow rate: 1.0 mL / min, retention time: 6. 5 min, detection: UV 254 nm, RI.

After concentrating the separated solution with an evaporator, it is dissolved in a solution for administration to a living body, the solution is passed through a membrane filter, and the ^{compound represented by the formula (1) having 11} C nuclei (2250 MBq, 54 GBq / μmol). ) Was collected in a vial.

[4: Precursor of compound represented by formula (2) (phenol precursor) and compound represented by formula (2)]
The precursor of the compound represented by the formula (2) (phenol precursor) and the compound represented by the formula (2) are basically described in J. Med. Chem., 2014, 57, 5129-5140. It was synthesized according to the method described. Specifically, a precursor of the compound represented by the formula (2) (phenol precursor) and a compound represented by the formula (2) were synthesized according to the method shown below. Hereinafter, a specific method will be described.

A dichloromethane solution (10 mL) containing NBS (800 mg, 4.52 mmol) was added to a dichloromethane solution (5 mL) containing compound 1 (620 mg, 4.52 mmol) under an ice bath. The mixture was then stirred at room temperature for 20 hours. The finished mixture was concentrated and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 2 (900 mg, 4.17 mmol, 92%) as shown below.

A dichloromethane solution (20 mL) containing compound 2 (900 mg, 4.17 mmol) was cooled to −78 ° C., and t-butyl nitrite (595 μL, 5.00 mmol) and boron trifluoride diethyl ether were added to the dichloromethane solution. A complex (772 μL, 6.26 mmol) was added. The mixture was then stirred at −78 ° C. for 3 hours and then at room temperature for 15 hours. To the mixture was further added 18-crown-6 (55 mg, 0.21 mmol) and potassium acetate (818 mg, 8.34 mmol), and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, the mixture was filtered through Celite, and the filtrate was concentrated. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 3 (427 mg, 1.55 mmol, 37%) as shown below.

In a chloroform solution (10 mL) containing compound 3 (427 mg, 1.55 mmol), p-toluenesulfonic acid (30 mg, 0.115 mmol) and 3,4-dihidoro-2H-pyran (280 μL, 3.1 mmol) were added. added. The mixture was then stirred at room temperature for 21 hours. The finished mixture was concentrated and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 4 (568 mg, 1.83 mmol) as shown below.

Compound 4 (1.79g, 5.75mmol) 1,4- dioxane / H 2 O solution containing (5: 1, 12 mL) to, 2- (Trifluoromethyl) benzeneboronicacid (1.15g , 6.05 mmol), carbonate Cesium (1.87 g, 5.75 mmol) and Pd (PPh ₃ ) ₄ (332 mg, 0.29 mmol) were added. The mixture was then heated at 130 ° C. for 3 hours using a microwave synthesizer. Water was added to the finished mixture, and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 5 (1.75 g, 4.65 mmol, 20%) as a yellow powder as shown below.

6M Hydrochloric Acid (3 mL, 18 mmol) was added to a methanol solution (10 mL) containing Compound 5 (482 mg, 1.28 mmol). The mixture was then stirred at room temperature for 20 hours. The finished mixture was concentrated and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with a sodium hydrogen carbonate solution and a saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 8 (344 mg, 1.18 mmol, 92%) as shown below.

To NMP solution (4 mL) containing Compound 5 (867 mg, 2.30 mmol) was added 1-Dodecanetic (807 μL, 3.45 mmol) and sodium hydroxide (276 mg, 6.90 mmol). Then, the mixture was stirred at 130 ° C. for 21 hours. The finished mixture was extracted with ethyl acetate. The obtained organic layer was washed with an aqueous citric acid solution and a saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 6 (825 mg, 2.28 mmol, 99%) as shown below.

6M Hydrochloric Acid (3 mL, 18 mmol) was added to a methanol solution (10 mL) containing Compound 6 (248 mg, 0.684 mmol). The mixture was then stirred at room temperature for 16 hours. The finished mixture was concentrated and the mixture was extracted with ethyl acetate. The obtained organic layer was washed with a sodium hydrogen carbonate solution and a saturated brine, and the organic layer was dried over sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography to obtain Compound 7 (187 mg, 0.673 mmol, 98%) as shown below.

^[5:11 with a C nuclei, the compound represented by formula (2)]
¹¹ C nuclei, using Sumitomo Heavy Industries Ltd. cyclotron CYPRIS HM-12S, manufactured by 14N (p, ^{α) 11} C nuclear reaction (current value 50 .mu.A, irradiation time 54 min) of. [ ¹¹ C] Methyl iodide is prepared in the first reaction vessel ^{using 11} CO ₂ gas as a starting material using a dedicated labeling synthesizer (manufactured by Sumitomo Heavy Industries, Ltd.) ¹¹ CO ₂ → ¹¹ CH ₃ OH → ¹¹ CH ₃ I was converted in this order and synthesized.

Phenol precursor (1.14 mg, 4.0 μmol), 1M NaOH (4.1 μL, 4.1 μmol) and DMF (450 μL) were prepared in advance in the second reaction vessel, and synthesized in the first reactor. The ¹¹ CH ₃ I was distilled and transferred to the second reaction vessel. Subsequently, the temperature in the second reaction vessel was set to 90 ° C., and the mixture in the second reaction vessel was reacted for 4 minutes.

After the reaction, the second reaction vessel was cooled to room temperature and the above mixture was purified by HPLC. FIG. 4 shows a preparative HPLC chart of the compound represented by the formula (2) having ^{11 C nuclei.} The preparative conditions by HPLC are: column: COSMOSIL 5-C ₁₈ MS-II 10 × 20 mm, 10 × 250 mm, developing solvent: CH ₃ CN: H ₂ O = 50: 50, flow rate: 6.0 mL / min, retention time. 11.3 min, detection: UV 254 nm, RI. Further, FIG. 5 shows an analytical HPLC chart of the compound represented by the formula (2) having ^{an 11 C nucleus.} The analysis conditions by HPLC were column: COSMOSIL 5-C ₁₈ AR-II 4.6 × 150 mm, developing solvent: CH ₃ CN: H ₂ O = 55: 45, flow rate: 1.0 mL / min, retention time: 5. 2 min, detection: UV 254 nm, RI.

After concentrating the separated solution with an evaporator, it is dissolved in a solution for administration to a living body, the solution is passed through a membrane filter, and the ^{compound represented by the formula (2) having 11} C nuclei (4430 MBq, 82.6 GBq). / Μmol) was collected in a vial.

[6: PET imaging]
^For PET imaging of the compound represented by the formula (1) having 11 C nuclei, a Sprague Dawley rat 8 to 9 weeks old and weighing about 290 g was used. On the other ^hand, in the PET imaging of the compound represented by formula (2) having a ¹¹ C nucleus, using 8-9 weeks old, Sprague Dawley rats weighing approximately 300 g.

Thirty minutes prior to the start of the scan, a route was placed in the tail vein of the rat under 1.5% isoflurane anesthesia (1.5% isoflurane, nitrous oxygen / oxygen (7: 3)) and the rat was placed in the tail vein of the rat for small animals. It was placed in a prone position on a PET scanner (microPET Focus-220; Siemens) bed. The body temperature of the rat was maintained at about 37 ° C. by a temperature probe inserted into the rat's rectum and a heat pad connected to the temperature probe.

Simultaneously with the start of the scan, from the tail vein route, the ^{compound represented by the formula (1) having an 11} C nucleus (about 100 MBq / 0.2 mL) or the compound represented by the formula (2) having ^{an 11 C nucleus (2).} Approximately 100 MBq / 0.2 mL) was administered bolus and 60 minutes of emission data were collected in 3D list mode. In the head scan, emission data was collected by dividing into 6 × 10s, 6 × 30s, 11 × 60s, and 15 × 180s dynamics synograms. In the whole body scan, imaging was performed by a continuous bed moving method of 1 pass 180 s.

Images were reconstructed using the collected emission data according to the standard 2-dimensional filtered backprojection (FBP) algorithm, and the images were analyzed using PMOD (version 3.7).

[Test 1. Evaluation test of agonist activity against TRPA1]
In order to examine the agonist activity of the synthesized compound against TRPA1, a calcium assay was performed using HEK293 cells (human fetal kidney-derived cells) that transiently expressed the mouse-derived TRPA1 channel (mTRPA1).

First, a gene encoding mTRPA1 was introduced into HEK293 cells by a lipofection method, and mTRPA1 was expressed on the cell membrane. Specifically, after introducing a plasmid DNA (pCI-neo (promega)) into which a gene encoding mTRPA1 has been inserted into HEK293 cells using a lipofection agent, the HEK293 cells are introduced at 37 ° C. for 24 to 48 hours. It was cultured.

Next, the change in calcium ion concentration in HEK293 cells expressing mTRPA1 was measured. Specifically, HEK293 cells were peeled off from the culture plate using trypsin, the HEK293 cells were re-spread on the cover glass, and then cultured again at 37 ° C. for 3 hours. A calcium indicator (Fura-2 AM) was added to the medium, and HEK293 cells were cultured at 37 ° C. for 30 minutes, and the cells were allowed to take up the calcium indicator. As the extracellular solution, a Ca ²⁺ -containing solution was prepared. The specific composition of the Ca ²⁺ -containing solution was 2 mM CaCl ₂ , 132 mM NaCl, 4 mM KCl, 1 mM MgCl ₂ , 5 mM glucose, 5 mM HEPES (pH 7.4).

After HEK293 cells incorporating the calcium indicator were ^{placed in a Ca 2+} -containing solution, the fluorescence intensity (510 nm) of the calcium indicator was measured over time using ARGUS CA-20 (Hamamatsu Photonics). Specifically, the following operations 1 to 3 were performed:
Step 1: At the start of the test (0 minutes), HEK293 cells incorporating a calcium indicator were placed in a ^{Ca 2+ -containing solution;}
Operation 2: After 2 minutes, the compound to be tested (RLC-TA1002, RLC-TA1003, or RLC-TA1004) was added to the ^{Ca 2+ -containing solution;}
After 3:10 minutes of operation, the measurement of fluorescence intensity was completed.

The amount of the compound in the Ca ²⁺ -containing solution was 0.01 μM, 0.1 μM, 1.0 μM, 10.0 μM, or 100.0 μM. Further, a solution containing 0.1% DMSO instead of the compound was prepared in ^{the Ca 2+ -containing solution, and this was used as a control.} In the analysis, in each cell, the value obtained by subtracting the average value from 0 to 1 minute after the start of measurement from the maximum response value from 2 minutes to 10 minutes after the start of measurement was calculated as the response change value (ΔRatio). .. Response change values were calculated from 20 or more cells, and the average value of these response change values was used as the test result.

FIG. 3 shows the test results (concentration-response curve). The agonist activity (EC50) for mTRPA1 was 141 nM, 335 nM, 475 nM for each of Compound 1-6b (RLC-TA1002), Compound 1-6c (RLC-TA1003), and Compound 1-6d (RLC-TA1004). .. Therefore, it was found that the compound of the present invention (particularly, the compound represented by the formula (1) or a salt thereof) has an agonist activity against TRPA1.

[Test 2. ¹¹ PET imaging using a compound represented by the formula (1) having a C nucleus]
^{A compound represented by the formula (1) having 11} C nuclei (see FIG. 6 for the specific structure of the compound) was administered to rats, and PET imaging data of the rats were obtained.

Figure 6 shows PET is the result of imaging, whole body scan image of a rat with a compound of formula (1) having a ^{11 C} nucleus. The detailed conditions for the PET imaging were: specific activity at the time of administration: 18.5 GBq / μmol, radioactivity administered: 87.9 MBq, amount of compound administered: 4.8 nmol, animals used: male SD rat, 9 weeks old, It was 286.1 g.

From FIG. 6, characteristic accumulation in the lungs of rats was observed with respect to the compound represented by the formula (1) and its salt. This revealed that TRPA1 expressed in the lung was imaged. It is considered that TRPA1 expressed in the lung functions as an oxygen sensor.

FIG. 7 shows a scanned image of the head of the same rat. The detailed conditions for the PET imaging were: specific activity at the time of administration: 44.0 GBq / μmol, radioactivity administered: 94.8 MBq, amount of compound administered: 2.4 nmol, animal used: male SD rat, 9 weeks old, It was 312.1 g.

From FIG. 7, it was observed that with respect to the compound represented by the formula (1) and its salt, the characteristic accumulation in the rat brain and the difference in the degree of accumulation depending on the site in the brain were observed. This revealed that TRPA1 expressed in the brain was imaged. Further, it has been clarified that the compound represented by the formula (1) and a salt thereof are particularly useful for imaging while distinguishing a specific region in the brain from other regions in the brain.

[Test 3. ¹¹ PET imaging using a compound represented by the formula (2) having a C nucleus]
^{A compound represented by the formula (2) having 11} C nuclei (see FIG. 8 for the specific structure of the compound) was administered to rats, and PET imaging data of the rats were obtained.

8 shows a PET is the result of imaging, the rats systemic scanned image using the compound represented by formula (2) having a ^{11 C} nucleus. The detailed conditions for the PET imaging were: specific activity at the time of administration: 66.5 GBq / μmol, radioactivity administered: 96.7 MBq, amount of compound administered: 1.5 nmol, animal used: male SD rat, 9 weeks old, It was 294.3 g.

From FIG. 8, characteristic accumulation on the body surface of the rat was observed with respect to the compound represented by the formula (2) and its salt. This revealed that TRPA1 expressed on the body surface was imaged.

FIG. 9 shows a scanned image of the head of the same rat. The detailed conditions for the PET imaging were: specific activity at the time of administration: 67.9 GBq / μmol, radioactivity administered: 97.2 MBq, amount of compound administered: 1.4 nmol, animal used: male SD rat, 9 weeks old, It was 293.6 g.

From FIG. 9, characteristic accumulation in the rat brain was observed with respect to the compound represented by the formula (2) and its salt. This revealed that TRPA1 expressed in the brain was imaged. Further, it was clarified that the compound represented by the formula (2) and its salt were input into the brain in a short time and then rapidly excreted from the brain.

The present invention can be suitably used as a bioimaging agent specific for TRPA1.

Claims (6)

A compound represented by the following formula (1) or formula (2), or a salt thereof.

(In formula (1), R ¹ is a substituent having a radioactive isotope.)

(In formula (2), R ² is a substituent having a radioactive isotope.) R ¹ and R ² are independently halogen radioisotopes, alkyl groups with radioisotopes, alkyl groups substituted with radioisotopes, alkoxy groups with radioisotopes, and radioisotopes, respectively. The compound according to claim 1, or a salt thereof, which is a substituent selected from the group consisting of an alkoxy group substituted with. A bioimaging agent containing the compound according to claim 1 or 2 or a salt thereof as an active ingredient. The bioimaging agent according to claim 3, which is for imaging TRPA1. The bioimaging agent according to claim 3 or 4, which is used for PET imaging or evaluation of a pathological condition that affects the expression level of TRPA1. A bioimaging kit comprising a compound represented by the following formula (1) or the general formula (2), or a salt thereof.

(In formula (1), R ¹ is a substituent having a radioactive isotope.)

(In formula (2), R ² is a substituent having a radioactive isotope.)

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