WO2019216223A1 - Non-invasive diagnostic imaging agent for heart disease - Google Patents

Abstract

The present invention provides compounds that accumulate at a high level in cardiac lesions and are suitable as a nuclear medicine tracer in PET imaging, enables in vivo detection of cardiac lesions by using said compounds, and provides a non-invasive diagnostic imaging agent for heart disease containing as an active ingredient a radiolabeled compound represented by formula (1) or a salt thereof. [In the formula, X₁ represents a hydrogen atom or a halogen atom, X₂ represents a fluorine atom or a nitrile group, and X₃ represents a radioactive fluorine atom.]

Description

Non-invasive diagnostic imaging agent for heart disease

The present invention relates to a noninvasive diagnostic imaging agent for heart disease.

In chronic heart failure, left ventricular remodeling such as ventricular hypertrophy and fibrosis proceeds in the heart, and it has been reported that the renin-angiotensin-aldosterone system (RAAS) is related to this process. RAAS is a circulatory regulation mechanism that regulates blood pressure in the body, but recently, in addition to this systemic circulatory RAAS, data indicating the presence of RAAS and aldosterone synthesizing system in the heart region has been reported.

For example, Non-Patent Document 1 describes that blood collected by cardiac catheterization showed that aldosterone was synthesized and secreted in a human failing heart.

Also, Non-Patent Document 2 reveals that the gene expression of CYP11B2, which is an aldosterone synthase, is enhanced by examination using an autopsy heart. And it has been shown that this increased expression of CYP11B2 gene is associated with myocardial fibrosis and cardiac dysfunction.

In addition, various compounds that selectively inhibit CYP11B2 have been developed, and attempts have been made to treat cardiovascular diseases by selectively inhibiting CYP11B2 (Patent Documents 1 to 3, Non-patent Documents 3 to 3). 5).

Although not intended for cardiovascular diseases, various radioactive compounds having high selectivity for CYP11B2 have been developed for the purpose of depicting the lesions of the adrenal glands and enabling imaging diagnosis of primary aldosteronism ( (Patent Documents 4 to 11, Non-Patent Document 6)

There is an international publication 2017/213247 pamphlet as a non-invasive method for detecting the expression of CYP11B2 in the heart, and a SPECT or PET tracer has been reported for cardiac imaging in vivo. It has been shown that nuclear medicine diagnosis of myocardial remodeling can be performed.

Special table 2013-512271 gazette Special table 2011-520799 gazette Special table 2014-526539 gazette Special table 2013-534911 gazette JP 2014-129315 A Japanese Patent Laying-Open No. 2015-093831 Japanese Patent Laying-Open No. 2015-093932 Japanese Patent Laying-Open No. 2015-093833 JP 2015-110563 A JP2015-193545A International Publication 2015/199205 Pamphlet International Publication 2017/213247 Pamphlet

Detecting the expression of CYP11B2 in the heart region of heart disease patients may lead to the evaluation of the progression of heart diseases such as heart failure. In the early stage of heart disease, it is thought that the lesion area gradually increases from a minute lesion of about several millimeters. By detecting the lesion earlier, the timing of treatment intervention can be advanced, and the prognosis There is a possibility that it can contribute to improvement.

Nuclear medicine diagnosis using single photon tomography (SPECT) and positron emission tomography (PET) is one of the methods for detecting changes in the molecular level in vivo.

The present inventor has already created a heart failure model rat, confirmed that the expression of CYP11B2 is increased in the cardiac lesion, and further, nuclear medicine examination using a radiolabeled compound capable of binding to aldosterone synthase This shows that CYP11B2 expressed in the lesion can be detected (Patent Document 12). However, it is not clear whether the expression level of CYP11B2 is increased to a level detectable by a nuclear medicine examination using SPECT or PET in a minute lesion of heart disease. In addition, in order to evaluate the progression of minute lesions over time, a tracer that is applicable to a modality with excellent quantitativeness and has high ability to bind to a target is used, and after administration of a radiolabeled compound, There is a need to wait until the tracer accumulates in the heart lesion to such an extent that it can be detected by a nuclear medicine examination.

Here, the exposure dose in the body produced by administering the radiolabeled compound into the living body increases in proportion to the exposure amount and the exposure time. When a nuclear medicine test requires a relatively long waiting time, and the exposure time increases, the exposure dose in the body also increases, and the number of tests that can be performed may be limited due to the relationship with the threshold dose for organ damage caused by radiation. There is. Therefore, it has been desired to develop a tracer by PET that is superior in spatial resolution and quantitativeness for detection of minute lesions of heart disease and evaluation of the progression of the disease over time, and has a short waiting time after administration.

Radioactive fluorine (fluorine-18) has a half-life of 110 minutes and is a nuclide for PET that is widely used clinically. Patent Document 12 shows SPECT and PET tracer data, but compared to SPECT tracer, PET, especially fluorine-18 tracer, is weakly accumulated in the cardiac lesion. The inventor's knowledge revealed that the image was not drawn.

The present invention has been made in view of the above circumstances, and has a high accumulation property in a cardiac lesion, and provides a compound suitable as a tracer for nuclear imaging examination of PET imaging. By using the compound, a cardiac lesion is obtained. Is to be detected in vivo.

According to the present invention, there is provided a noninvasive diagnostic imaging agent for heart disease containing a radiolabeled compound represented by the following formula (1) or a salt thereof as an active ingredient.

[Wherein, X ₁ represents a hydrogen atom or a halogen atom, X ₂ represents a fluorine atom or a nitrile group, and X ₃ represents a radioactive fluorine atom. ]

According to the present invention, it is possible to noninvasively detect a heart disease lesion, and in particular, it is possible to depict a heart lesion portion by PET imaging.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

1A and 1B are diagrams showing the results of autoradiography of compound [ ¹⁸ F] 101 and compound [ ¹⁸ F] 100 using ischemic heart disease model rat heart sections, respectively. FIG. 2 is a bar graph showing the signal intensity of the ischemia / reperfusion site relative to the signal intensity of the standard radiation source in the autoradiography of FIG. FIG. 3A is a PET imaging image of an ischemic heart disease model rat administered with compound [ ¹⁸ F] 101, FIG. 3B is a PET imaging image of a normal rat administered with [ ¹⁸ F] 101, and FIG. , PET imaging images of ischemic heart disease model rats administered with compound [ ¹⁸ F] 100. In the figure, (a) is a short-axis cross-sectional image, (b) is a horizontal long-axis cross-sectional image, and (c) is a vertical long-axis cross-sectional image. The triangular arrowhead indicates the ischemic site of the heart, the arrow indicates the heart site, and the pentagonal arrow indicates the liver.

The present invention is a noninvasive diagnostic imaging agent for heart disease, which contains a radioactive fluorine-labeled compound represented by the above formula (1) or a salt thereof as an active ingredient. According to the diagnostic imaging agent of the present invention, it is possible to depict a site where the fibrosis of the heart is progressing.

In the present invention, the “noninvasive diagnostic imaging agent” is used for nuclear medicine diagnosis, and more specifically, used for positron emission tomography (PET).

In the present invention, the “heart disease” includes ischemic heart disease and non-ischemic heart disease, preferably a disease caused by fibrosis of the heart, and an example is heart failure.
In the present invention, the “ischemic heart disease” is not limited as long as it is a heart disease caused by myocardial ischemia, and examples thereof include coronary heart disease angina, myocardial infarction, acute coronary syndrome, ischemic heart failure and the like. .
In the present invention, “non-ischemic heart disease” includes myocarditis, hypertensive heart disease, dilated cardiomyopathy, hypertrophic cardiomyopathy, non-ischemic heart failure, and the like.

In the present invention, from the viewpoint of improving the imaging ability of heart disease, in the above formula (1), when X ₁ is a hydrogen atom, X ₂ is preferably a fluorine atom. From the same viewpoint, in the above formula (1), when X ₁ is a halogen atom, X ₂ is preferably a fluorine atom or a nitrile group. From the same viewpoint, in the above formula (1), when X ₁ is a fluorine atom, X ₂ is preferably a fluorine atom or a nitrile group.
In the above formula (1), by using a radioactive fluorine atom as X ₃ , it can be applied to the use of a diagnostic imaging agent for nuclear medicine examination, more specifically for positron emission tomography (PET). In the present invention, since a narrow site of heart disease is to be imaged, it is preferable to use positron emission tomography with good spatial resolution and quantitativeness.

Preferred embodiments of the compound according to the present invention include three compounds represented by the following chemical formula.

The radioactive compound according to the present invention represented by the above formula (1) or a salt thereof can be produced, for example, according to the production method described in Patent Document 11 (International Publication No. 2015/199205). From the compound represented by the formula (2) or a salt thereof, it can be produced by a radiofluorination reaction.

In the above formula (2), X ₁ represents a hydrogen atom or a halogen atom, X ₂ represents a fluorine atom or a nitrile group, R ₁ represents a halogen atom, a substituted or unsubstituted alkylsulfonyloxy group, or a substituted or unsubstituted aryl. A sulfonyloxy group is shown.

In the above formula (2), preferred embodiments of X ₁ and X ₂ are the same as those described above for the above formula (1). In the above formula (2), the substituted or unsubstituted alkylsulfonyloxy group is preferably an alkylsulfonyloxy group having 1 to 12 carbon atoms. In the substituted alkylsulfonyloxy group, a hydrogen atom of the alkyl chain may be substituted with a halogen atom. In the present invention, the substituted or unsubstituted arylsulfonyloxy group is preferably a substituted or unsubstituted benzenesulfonyloxy group, more preferably a substituted benzenesulfonyloxy group. In the substituted arylsulfonyloxy group, the hydrogen atom of the aryl ring is preferably substituted with an alkyl group having 1 to 12 carbon atoms or a nitro group. Preferable specific examples of the substituted or unsubstituted alkylsulfonyloxy group and the substituted or unsubstituted arylsulfonyloxy group include a methanesulfonyloxy group, a benzenesulfonyloxy group, a p-toluenesulfonyloxy group, a p-nitrobenzenesulfonyloxy group, and trifluoromethane. A sulfonyloxy group is mentioned.

Hereinafter, an example of a method for producing the radioactive compound represented by the above formula (1) will be described using the following scheme 1. In the compound represented by the above formula (1), a compound in which X ₃ is a hydroxy group is used as a starting material, and the group represented by R ₁ in the above formula (2) (halogen atom, substituted or unsubstituted alkylsulfonyl) An oxy group or a substituted or unsubstituted arylsulfonyloxy group) is introduced to obtain a compound represented by the above formula (2) as a labeling precursor (Scheme 1, step a). Next, a nucleophilic substitution reaction is performed on the group represented by R ₁ using a radiohalide ion to obtain a radioactive compound represented by the above formula (1) (Scheme 1, step b).

Here, “radiohalide ions” include radioactive fluoride ions (for example, [ ¹⁸ F] fluoride ions). As a labeling precursor, in the compound represented by the formula (2), R ₁ is a chlorine atom, a bromine atom, an iodine atom, a substituted or unsubstituted alkylsulfonyloxy group, or a substituted or unsubstituted arylsulfonyloxy group. Preferably there is. In addition, the nucleophilic substitution reaction using radioactive fluoride ions is preferably performed in the presence of a base such as an alkali metal carbonate (for example, sodium carbonate or potassium carbonate).

For example, by performing a radioactive fluorination reaction using radioactive fluoride ions, a radioactive compound in which X ₃ is a radioactive fluorine atom in the radioactive compound represented by the formula (1) can be obtained. The radiofluorination reaction is preferably carried out in the presence of a base. 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo [8.8.8] -hexacosane (trade name: Cryptofix 222 ) And the like in the presence of various phase transfer catalysts.

When the radioactive compound represented by the above formula (1) or a salt thereof is used as a medicine, after the radioactive fluorination reaction, a column filled with unreacted radioactive fluorine and insoluble impurities with a membrane filter and various packing materials. Purification by HPLC or the like is desirable.

In the present invention, the “salt” may be anything that is pharmaceutically acceptable. For example, inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, or acetic acid, trifluoroacetic acid, maleic acid, succinic acid, mandelic acid, fumaric acid, malonic acid, pyruvic acid, oxalic acid, glycol Acid, salicylic acid, pyranosidic acid (glucuronic acid, galacturonic acid, etc.), α-hydroxy acid (citric acid, tartaric acid, etc.), amino acid (aspartic acid, glutamic acid, etc.), aromatic acid (benzoic acid, cinnamic acid, etc.), sulfone Salts derived from organic acids such as acids (p-toluenesulfonic acid, ethanesulfonic acid, etc.) can be used.

The noninvasive diagnostic imaging agent of the present invention is a formulation containing the above-mentioned radioactive fluorine-labeled compound or a salt thereof in a form suitable for administration into a living body. This non-invasive diagnostic imaging agent is preferably administered parenterally, that is, by injection, and more preferably an aqueous solution. Such compositions may optionally contain additional components such as pH adjusters, pharmaceutically acceptable solubilizers, stabilizers or antioxidants.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these contents.

In the examples, the molecular structure of each compound was identified by ¹ H-NMR spectrum. As the NMR apparatus, AVANCE III (manufactured by Bruker) was used, the resonance frequency was 500 MHz, tetramethylsilane (TMS) was used as an internal standard, and TMS resonance was set to 0.00 ppm. All chemical shifts are in ppm on the delta scale (δ), and for signal fine splitting, the abbreviations (s: singlet, d: doublet, t: triplet, dd: double doublet, dt: double triplet, m: (Multiplet, bs: broad singlet, quin: quintet).
In the following examples, “room temperature” is 25 ° C.
In the synthesis examples of each compound, each step in the compound synthesis was repeated as necessary, and an amount necessary for use as an intermediate or the like in other synthesis was ensured.

(Reference Example 1) Synthesis of Compound 100 Compound 100 was synthesized according to the scheme shown in FIG. 1 of International Publication No. 2015/199205.

According (Reference Example 2) Compound ^[18 F] 100 Synthesis WO 2015/199205 scheme shown in Figure 2 of the, was synthesized compound ^[18 F] 100.

Example 1 Synthesis of Compound 101 Compound 101 was synthesized according to Scheme 2 below.

Synthesis of N- (5-fluoro-2-nitrophenyl) -2-fluoroethylamine (Compound 2) 2,4-Difluoronitrobenzene (Compound 1) (109.7 μL, 1.0 mmol) in dichloromethane (3.0 mL) After dissolution, potassium carbonate (691.0 mg, 5.0 mmol) and 2-fluoroethylamine (298.6 mg, 3.0 mmol) were added under argon gas atmosphere and ice cooling, followed by stirring at room temperature for 2 days. . After completion of the reaction, water was added at room temperature, followed by extraction with dichloromethane three times. The combined dichloromethane layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel chromatography (eluent: n-hexane / ethyl acetate = 20/1 → 10/1), and N- ( 5-Fluoro-2-nitrophenyl) -2-fluoroethylamine (Compound 2) (231.2 mg, 1.14 mmol) was obtained.
¹ H-NMR of compound 2 (solvent: deuterated chloroform): δ 8.36 (bs, 1H), 8.25 (dd, J = 9.5, 6.1 Hz, 1H), 6.52 (dd, J = 11.3, 2.6 Hz, 1H), 6.44-6.41 (m, 1H), 4.70 (dt, J = 47, 5.0 Hz, 2H), 3.62 (dq, J = 25) 4.1 Hz, 2H).

Synthesis of 3-fluoro-N- [2-fluoroethyl] -1,6-phenylenediamine (compound 3) N- (5-fluoro-2-nitrophenyl) -2-fluoroethylamine (compound 2) (231.2 mg , 1.14 mmol) was dissolved in ethyl acetate (4.0 mL), and then tin (II) chloride (867.4 mg, 4.57 mmol) and water (82.3 μL, 4.57 mmol) were added. And refluxed for 8 hours. After completion of the reaction, 4M aqueous sodium hydroxide solution was added, the deposited precipitate was filtered, and the obtained filtrate was extracted three times with ethyl acetate. The combined ethyl acetate layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: n-hexane / ethyl acetate = 5/1 → 2/1). 3-fluoro-N- [2-fluoroethyl] -1,6-phenylenediamine (Compound 3) (137.9 mg, 0.801 mmol) was obtained.
¹ H-NMR of compound 3 (solvent: deuterated chloroform): δ 6.66-6.63 (m, 1H), 6.39-6.35 (m, 2H), 4.67 (dt, J = 47, 4.9 Hz, 2H), 3.41 (dt, J = 27, 4.8 Hz, 1H), 3.18 (bs, 2H).

Synthesis of 5- {6-Fluoro-1- [2-fluoroethyl] benzimidazol-2-yl} pyridine-3-methanol (Compound 4) 5-Hydroxymethyl-3-pyridinecarboxaldehyde (109.9 mg, 0. 801 mmol) was dissolved in N, N′-dimethylformamide (1 mL), and then under ice-cooling, 3-fluoro-N- [2-fluoroethyl] -1,6-phenylenediamine (Compound 3) (137.9 mg) , 0.801 mmol) dissolved in N, N′-dimethylformamide solution (2 mL) and Oxone® monopersulfate compound (590.8 mg, 0.961 mmol) were added at room temperature under an argon gas atmosphere. Stir for 2 hours 30 minutes. After completion of the reaction, a saturated aqueous sodium thiosulfate solution and a saturated aqueous sodium hydrogen carbonate solution were added under ice-cooling, and the mixture was extracted 3 times with ethyl acetate. The combined ethyl acetate layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: ethyl acetate / n-hexane / methanol = 10/5/1). , 5- {6-fluoro-1- [2-fluoroethyl] benzimidazol-2-yl} pyridine-3-methanol (Compound 4) (148.7 mg, 0.514 mmol) was obtained.
¹ H-NMR of compound 4 (solvent: deuterated chloroform): δ 8.87 (d, J = 2.1 Hz, 1H), 8.76 (d, J = 2.1 Hz, 1H), 8.13 (t, J = 2.1 Hz, 1H), 7.78 (dd, J = 8.9, 4.9 Hz, 1H), 7.15-7.09 (m, 2H), 4.86 (d, J = 5 .6 Hz, 2H), 4.80 (dt, J = 47, 4.8 Hz, 2H), 4.50 (dt, J = 25, 4.8 Hz, 2H).

Synthesis of 6-fluoro-1- (2-fluoroethyl) -2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzimidazole (Compound 101) 5- {6-Fluoro-1- [2 -Fluoroethyl] benzimidazol-2-yl} pyridine-3-methanol (compound 4) (148.7 mg, 0.514 mmol) was dissolved in tetrahydrofuran (5 mL), and then triethylamine (214.3 μL, 1.54 mmol) was added. added. Further, p-toluenesulfonic anhydride (335.5 mg, 1.03 mmol) was added at −20 ° C., and the mixture was stirred at −20 ° C. for 4 hours under an argon gas atmosphere. Further, triethylamine (214.3 μL, 1.54 mmol) and p-toluenesulfonic anhydride (335.5 mg, 1.03 mmol) were added, and the mixture was stirred at −20 ° C. for 3 hours under an argon gas atmosphere. After completion of the reaction, triethylamine (1.1 mL, 7.71 mmol) and imidazole (349.9 mg, 5.14 mmol) were added, and the mixture was stirred overnight at room temperature under an argon gas atmosphere. After completion of the reaction, purification was performed by silica gel chromatography (eluent: chloroform / methanol = 20/1), and the obtained fraction was concentrated under reduced pressure, dissolved in ethyl acetate and washed with saturated aqueous sodium hydrogen carbonate solution. Subsequently, the washed ethyl acetate layer was dried over anhydrous sodium sulfate and concentrated to give 6-fluoro-1- (2-fluoroethyl) -2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzo Imidazole (Compound 101) (31.5 mg, 0.0931 mmol) was obtained.
¹ H-NMR of compound 101 (solvent: deuterated chloroform): δ 8.94 (d, J = 2.0 Hz, 1 H), 8.64 (d, J = 2.2 Hz, 1 H), 7.87 (t, J = 1.9 Hz, 1H), 7.77 (dd, J = 9.5, 4.9 Hz, 1H), 7.62 (s, 1H), 7.14 (s, 1H), 7.13- 7.09 (m, 2H), 6.96 (t, J = 1.3 Hz, 1H), 5.26 (s, 2H), 4.77 (dt, J = 47, 4.7 Hz, 2H), 4.42 (dt, J = 25, 4.8 Hz, 2H).

According (Example 2) the following synthetic Scheme 2 compounds ^[18 F] 101, was synthesized compound ^[18 F] 101.

Synthesis of 2- (tert-butyldiphenylsilyloxy) ethylamine (Compound 6) 2-Aminoethanol (Compound 5) (2.2 mL, 40.0 mmol) was dissolved in dichloromethane (100 mL), and then at room temperature, tert. -Butyldiphenylsilyl chloride (15.6 mL, 60.0 mmol) and imidazole (5.44 g, 80.0 mmol) were added, and the mixture was stirred overnight at room temperature under an argon gas atmosphere. After completion of the reaction, water was added under ice cooling, followed by extraction with dichloromethane three times. The combined dichloromethane layer was dried over anhydrous sodium sulfate and then concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: ethyl acetate → ethyl acetate / methanol = 10/1 → 5/1). , 2- (tert-butyldiphenylsilyloxy) ethylamine (Compound 6) (12.2 g, 40.7 mmol) was obtained.
¹ H-NMR of compound 6 (solvent: deuterated chloroform): δ 7.67-7.65 (m, 4H), 7.44-7.36 (m, 6H), 3.70 (t, J = 5. 3 Hz, 2H), 2.84 (t, J = 5.3 Hz, 2H), 2.79 (bs, 2H), 3.08 (bs, 2H), 1.07 (s, 9H).

Synthesis of N- (5-fluoro-2-nitrophenyl) -2- (tert-butyldiphenylsilyloxy) ethylamine (Compound 7) 2,4-Difluoronitrobenzene (Compound 1) (66.9 μL, 0.606 mmol) After dissolving in dichloromethane (2.0 mL), potassium carbonate (420.5 mg, 3.04 mmol) and 2- (tert-butyldiphenylsilyloxy) ethylamine (Compound 6) (compound 6) under argon gas atmosphere and ice cooling (546.7 mg, 1,83 mmol) was added, and the mixture was stirred overnight at room temperature. After completion of the reaction, water was added at room temperature, followed by extraction with dichloromethane three times. The combined dichloromethane layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel chromatography (eluent: n-hexane / ethyl acetate = 20/1 → 10/1), and N- ( 5-Fluoro-2-nitrophenyl) -2- (tert-butyldiphenylsilyloxy) ethylamine (Compound 7) (286.9 mg, 0.654 mmol) was obtained.
¹ H-NMR of compound 7 (solvent: deuterated chloroform): δ 8.51 (bs, 1H), 8.22 (dd, J = 9.5, 6.2 Hz, 1H), 7.67-7.65 ( m, 4H), 7.43-7.36 (m, 6H), 6.43 (dd, J = 11.5, 2.6 Hz, 1H), 6.37-6.33 (m, 1H), 3.90 (t, J = 5.4 Hz, 2H), 3.47 (q, J = 5.4 Hz, 2H), 1.07 (s, 9H).

Synthesis of 3-fluoro-N- [2- (tert-butyldiphenylsilyloxy) ethyl] -1,6-phenylenediamine (compound 8) N- (5-fluoro-2-nitrophenyl) -2- (tert- Butyldiphenylsilyloxy) ethylamine (Compound 7) (286.9 mg, 0.654 mmol) was dissolved in methanol (3.0 mL), and 10% palladium carbon (11.2 mg) was added under an argon gas atmosphere. . Subsequently, the mixture was stirred overnight at room temperature in a hydrogen gas atmosphere. After completion of the reaction, the mixture was filtered through Celite, the filtrate was concentrated under reduced pressure, and the crude product was purified by silica gel chromatography (eluent: n-hexane / ethyl acetate = 20/1 → 5/1) to give 3-fluoro -N- [2- (tert-butyldiphenylsilyloxy) ethyl] -1,6-phenylenediamine (Compound 8) (122.4 mg, 0.300 mmol) was obtained.
¹ H-NMR of compound 8 (solvent: deuterated chloroform): δ 7.67 (dd, J = 6.0, 1.3 Hz, 4H), 7.43-7.41 (m, 2H), 7.39- 7.36 (m, 4H), 6.62 (dd, J = 8.3, 5.7 Hz, 1H), 6.34-6.28 (m, 2H), 4.16 (bs, 1H), 3.91 (t, J = 5.4 Hz, 2H), 3.21 (q, J = 5.2 Hz, 2H), 3.08 (bs, 2H), 1.07 (s, 9H).

Synthesis of 5- {6-fluoro-1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazol-2-yl} pyridine-3-methanol (Compound 9) 5-hydroxymethyl-3-pyridinecarboxaldehyde (40.8 mg, 0.298 mol) was dissolved in N, N′-dimethylformamide (0.5 mL), and then under ice-cooling, 3-fluoro-N- [2- (tert-butyldiphenylsilyloxy) ethyl] -1,6-phenylenediamine (Compound 8) (122.4 mg, 0.300 mol) and Oxone (registered trademark) monopersulfate compound (221.3 mg, 0.360 mmol) were added, and the mixture was brought to room temperature under an argon gas atmosphere. And stirred for 30 minutes. After completion of the reaction, a saturated aqueous sodium thiosulfate solution and a saturated aqueous sodium hydrogen carbonate solution were added under ice cooling, followed by extraction with ethyl acetate three times. The combined ethyl acetate layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: ethyl acetate / n-hexane / methanol = 10/5/1). , 5- {6-Fluoro-1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazol-2-yl} pyridine-3-methanol (Compound 9) (131.3 mg, 0.250 mmol) was obtained. It was.
¹ H-NMR of compound 9 (solvent: deuterated chloroform): δ 8.96 (d, J = 2.1 Hz, 1H), 8.73 (d, J = 2.1 Hz, 1H), 8.12 (t, J = 2.1 Hz, 1H), 7.77 (dd, J = 8.8, 4.8 Hz, 1H), 7.38-7.36 (m, 6H), 7.29-7.28 (m 4H), 7.09-7.05 (m, 1H), 6.91 (dd, J = 8.7, 2.4 Hz, 1H), 4.76 (d, J = 5.8 Hz, 2H) 4.40 (t, J = 5.7 Hz, 2H), 3.94 (t, J = 5.7 Hz, 2H), 0.89 (s, 9H).

Synthesis of 6-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] -1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazole (Compound 10) 5- {6 -Fluoro-1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazol-2-yl} pyridine-3-methanol (Compound 9) (131.3 mg, 0.250 mmol) in dichloromethane (2.5 mL) Then, triethylamine (104.4 μL, 0.750 mmol) and p-toluenesulfonic anhydride (163.0 mg, 0.500 mmol) were added under ice-cooling, and the mixture was stirred at room temperature for 1 hour 30 hours under an argon gas atmosphere. Stir for minutes. After completion of the reaction, water was added and extracted three times with dichloromethane. The combined dichloromethane layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a crude product. Imidazole (85.0 mg, 1.25 mmol) was dissolved in N, N′-dimethylformamide (0.2 mL) and then ice-cooled. After adding triethylamine (174.1 μL, 1.25 mmol), the crude product obtained previously was dissolved in N, N′-dimethylformamide (0.8 mL) and added at room temperature under an argon gas atmosphere for 4 hours. Stir. After completion of the reaction, water was added and extracted three times with ethyl acetate. The combined ethyl acetate layers were dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: dichloromethane / methanol = 30/1 → 20/1 → 10/1). 6-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] -1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazole (Compound 10) (128.1 mg 0.222 mmol).
¹ H-NMR of compound 10 (solvent: deuterated chloroform): δ 9.06 (d, J = 2.2z, 1H), 8.55 (d, J = 2.2 Hz, 1H), 7.92 (t, J = 2.2 Hz, 1H), 7.76 (dd, J = 8.8, 4.8 Hz, 1H), 7.55 (s, 1H), 7.40-7.35 (m, 6H), 7.29-7.27 (m, 4H), 7.09-7.05 (m, 2H), 6.90-6.86 (m, 2H), 5.13 (s, 2H), 4. 34 (t, J = 5.5 Hz, 2H), 3.94 (t, J = 5.5 Hz, 2H), 0.89 (s, 9H).

Synthesis of 2- {6-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzimidazol-1-yl} ethanol (Compound 11) 6-Fluoro-2- [5- (imidazole -1-ylmethyl) pyridin-3-yl] -1- [2- (tert-butyldiphenylsilyloxy) ethyl] benzimidazole (Compound 10) (128.1 mg, 0.222 mmol) in tetrahydrofuran (2.0 mL) After dissolution, tetrabutylammonium fluoride (0.33 mL, tetrahydrofuran solution, about 1 M, 0.33 mmol) was added at room temperature, and the mixture was stirred at room temperature for 1 hour 30 minutes in an argon gas atmosphere. After completion of the reaction, the reaction solution was concentrated under reduced pressure, and the resulting crude product was purified by silica gel chromatography (eluent: dichloromethane / methanol = 20/1 → 10/1 → 5/1). 6-Fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzimidazol-1-yl} ethanol (Compound 11) (25.8 mg, 0.0765 mmol) was obtained.
¹ H-NMR of compound 11 (solvent: deuterated chloroform): δ 9.07 (d, J = 2.2 Hz, 1H), 8.64 (d, J = 2.2 Hz, 1H), 7.87 (t, J = 2.2 Hz, 1H), 7.73 (dd, J = 8.9, 4.8 Hz, 1H), 7.62 (s, 1H), 7.15 (d, J = 2.4 Hz, 1H) ), 7.13 (s, 1H), 7.12 (dt, J = 10.3, 2.4 Hz, 1H), 6.98 (t, J = 1.3 Hz, 1H), 5.27 (s) 2H), 4.21 (t, J = 5.7 Hz, 2H), 3.99 (t, J = 5.7 Hz, 2H), 2.44 (bs, 1H).

Synthesis of 6-chloro-5-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] -1- [2- (p-toluenesulfonyloxy) ethyl] benzimidazole (Compound 12) -{6-Fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzimidazol-1-yl} ethanol (Compound 11) (20.0 mg, 0.0593 mmol) in dichloromethane (1. (0 mL), p-toluenesulfonyl chloride (22.6 mg, 0.119 mol) and triethylamine (24.8 μL, 0.176 mmol) were added, and the mixture was stirred at room temperature for 3 hours in an argon gas atmosphere. After completion of the reaction, purification was performed by silica gel chromatography (eluent: chloroform / methanol = 20/1 → 10/1), and the obtained fraction was concentrated under reduced pressure, dissolved in ethyl acetate and washed with water. Subsequently, the washed ethyl acetate layer was dried over anhydrous sodium sulfate and concentrated to give 6-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] -1- [2- (p-toluene). [Sulfonyloxy) ethyl] benzimidazole (Compound 12) (10.9 mg, 0.0229 mmol) was obtained.
¹ H-NMR of compound 12 (solvent: deuterated methanol): δ 8.82 (d, J = 2.1 Hz, 1H), 8.70 (d, J = 2.1 Hz, 1H), 8.02 (t, J = 2.1 Hz, 1H), 7.90 (s, 1H), 7.62 (dd, J = 8.8, 4.7 Hz, 1H), 7.28 (dd, J = 6.4, 1 .8 Hz, 3 H), 7.21 (dd, J = 8.9, 2.4 Hz, 1 H), 7.13-7.10 (m, 1 H), 7.06 (t, J = 2.3 Hz, 3H), 5.46 (s, 2H), 4.49 (t, J = 5.9 Hz, 2H), 4.25 (t, J = 5.9 Hz, 2H), 2.32 (s, 3H) .

Synthesis of Compound [ ¹⁸ F] 101 [ ¹⁸ F] Fluoride ion-containing H ₂ ¹⁸ O (radioactivity 2330 MBq, corrected value at the start of synthesis) was added to a Sep-Pak column (trade name: Sep-Pak (registered trademark) Light Cartridge). The solution was passed through an Acculle (registered trademark) Plus QMA Carbonate, manufactured by Waters Inc., and a filler filling amount of 130 mg), and [ ¹⁸ F] fluoride ions were collected by adsorption. An acetonitrile solution (0.7 mL) of potassium carbonate aqueous solution (42.4 μmol / L, 0.3 mL) and Cryptofix 222 (trade name, manufactured by Merck) (14 mg, 37.2 μmol) was passed through this column, [ ¹⁸ F] fluoride ions were eluted. This was heated to 110 ° C. under argon gas to evaporate water, and then acetonitrile (0.5 mL × 2) was added to azeotrope to dryness. Here, 6-chloro-5-fluoro-2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] -1- [2- (p-toluenesulfonyloxy) ethyl] benzimidazole (Compound 12) ( A mixed solution (1.0 mL) of acetonitrile / dimethyl sulfoxide (9: 1) in which 5 mg, 0.0102 mmol) was dissolved was added and heated at 100 ° C. for 5 minutes. After completion of the reaction, water for injection (2.0 mL) was added and subjected to HPLC under the following conditions to give 6-fluoro-1- (2- [ ¹⁸ F] fluoroethyl) -2- [5- (imidazole-1- (Ilmethyl) pyridin-3-yl] benzimidazole (compound [ ¹⁸ F] 101) fraction was collected.
<HPLC conditions>
Column: Develosil RPAQUEOUS (trade name, manufactured by Nomura Chemical Co., Ltd., size: 10 × 250 mm)
Mobile phase: 10 mM ammonium bicarbonate solution / acetonitrile = 70/30
Flow rate: 4.0 mL / min Detector: UV-visible spectrophotometer (detection wavelength: 254 nm)
A solution 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, 130 mg of packing material), and 6-fluoro -1- (2- [ ¹⁸ F] fluoroethyl) -2- [5- (imidazol-1-ylmethyl) pyridin-3-yl] benzimidazole (compound [ ¹⁸ F] 101) was adsorbed and collected on the column. . After washing this column with 5 mL of water, 1 mL of ethanol was passed through and 6-fluoro-1- (2- [ ¹⁸ F] fluoroethyl) -2- [5- (imidazol-1-ylmethyl) pyridine-3- Il] benzimidazole (compound [ ¹⁸ F] 101) is eluted to give 6-fluoro-1- (2- [ ¹⁸ F] fluoroethyl) -2- [5- (imidazol-1-ylmethyl) pyridine-3 An ethanol solution of -yl] benzimidazole (compound [ ¹⁸ F] 101) was obtained. The amount of radioactivity obtained was 707 MBq (49 minutes after the start of synthesis) immediately after synthesis. Moreover, when the TLC analysis by the following conditions was conducted, the radiochemical purity was 98.3%.
<TLC analysis conditions>
TLC plate: Silica Gel 60 F ₂₅₄ (product name, manufactured by Merck)
Developing phase: acetonitrile / water / diethylamine = 10/1/1
RI detector: Rita Star, manufactured by raytest

Example 3 In Vitro Autoradiography Using Ischemic Heart Disease Model Rats Wistar rats (male) were thoracotomized under isoflurane anesthesia, the left coronary artery was ligated for 30 minutes, reperfused, thoraxed, and Bloody heart disease model rats were prepared.
One week after the operation, the model rat was sacrificed under isoflurane anesthesia, and then the heart was removed and sliced into 5 μm and attached to a slide glass (stored at −80 ° C. until use). The sections were returned from −80 ° C. to room temperature, and immersed as pre-incubation in phosphate buffered saline (PBS) at 37 ° C. for 5 minutes, and then immersed in human plasma at 37 ° C. for 5 minutes. Next, as a reaction step, human plasma containing compound [ ¹⁸ F] 101 (radioactivity concentration: about 40 kBq / mL) or compound [ ¹⁸ F] 100 (radioactivity concentration: about 40 kBq / mL) is prepared (hereinafter referred to as reaction). The pre-incubated section was immersed in the reaction solution at 37 ° C. for 10 minutes. Thereafter, the slices were washed by immersing in human plasma at 37 ° C. for 2 minutes and 5 times. The section after washing was sufficiently dried. In addition, a known amount of the reaction solution was immersed in a slide glass pasted with a filter paper cut out in a circle, and the dried product was used as a standard radiation source.
The section after drying and the standard radiation source were exposed to an imaging plate (BAS-SR2040, manufactured by Fuji Film), and an autoradiogram was obtained with a fluoro image analyzer (Typhoon FLA 7000 IP, manufactured by GE Healthcare Japan).

The result of compound [ ¹⁸ F] 101 is shown in FIG. 1A, and the result of compound [ ¹⁸ F] 100 is shown in FIG. 1B. As shown in FIG. 1A, accumulation of compound [ ¹⁸ F] 101 in the lesion area was confirmed. In contrast, as shown in FIG. 1B, almost no accumulation of compound [ ¹⁸ F] 100 in the lesion area was observed.

For the autoradiograms of Compound [ ¹⁸ F] 101 and Compound [ ¹⁸ F] 100, the ROI is taken at the ischemia reperfusion site, and the radioactivity count (correction value) at each site is used as the correction value for the standard radiation source. ) And compared.

The result is shown in FIG. 2 (n = 1). FIG. 2 is a bar graph showing the signal intensity of the ischemia / reperfusion site relative to the signal intensity of the standard radiation source in the autoradiography of FIG. As shown in FIG. 2, accumulation of compound [ ¹⁸ F] 101 in the lesion area was confirmed, but accumulation of compound [ ¹⁸ F] 100 in the lesion area was hardly observed.

(Example 4) PET imaging experiment using ischemic heart disease model rats Wistar rats (male) were thoracotomized under isoflurane anesthesia, and the left coronary artery was ligated for 30 minutes, then reperfused, closed, and ischemic. A heart disease model rat was prepared.
Compound [ ¹⁸ F] 101 is administered to the model rat one week after surgery (approximately 40 MBq / animal), and imaging is performed for approximately 10 minutes using a PET apparatus (exploreVISTA, manufactured by GEHC) 60 minutes after administration. Carried out. The results are shown in FIG. 3A.
The same experiment was conducted using normal rats (control rats). The results are shown in FIG. 3B. Further, compound [ ¹⁸ F] 100 was administered to a model rat prepared in the same manner as described above one week after the operation (about 40 MBq / animal), and immediately after the administration, it was dynamic and used for 60 minutes after the administration using the PET apparatus. Imaging was performed, and the image of the last frame (10 minutes), that is, the image from 50 minutes to 10 minutes after administration, is shown in FIG. 3C.
3A to 3C, (a) is a short-axis cross-sectional image, (b) is a horizontal long-axis cross-sectional image, and (c) is a vertical long-axis cross-sectional image. The triangular arrowhead indicates the ischemic site of the heart, the arrow indicates the heart site, and the pentagonal arrow indicates the liver.
As is clear from the comparison between FIG. 3A and FIG. 3B, the compound [ ¹⁸ F] 101 of the present invention was accumulated in the model rat lesion (ischemic site), and the lesion (ischemic site) could be depicted.
Further, the comparison between FIG. 3A and FIG. 3C shows that the lesioned part of the compound [ ¹⁸ F] 101 of the present invention can be depicted more than the compound [ ¹⁸ F] 100.

This application claims priority based on Japanese Patent Application No. 2018-089920 filed on May 8, 2018, the entire disclosure of which is incorporated herein.

Claims (9)

1. A noninvasive diagnostic imaging agent for heart disease, containing a radiolabeled compound represented by the following formula (1) or a salt thereof as an active ingredient.
   

   

   
   [Wherein, X ₁ represents a hydrogen atom or a halogen atom, X ₂ represents a fluorine atom or a nitrile group, and X ₃ represents a radioactive fluorine atom. ]
2. The noninvasive diagnostic imaging agent according to claim ₁ , wherein in the formula (1), X ₁ is a hydrogen atom.
3. The noninvasive diagnostic imaging agent according to claim ₂ , wherein X2 in the formula (1) is a fluorine atom.
4. The noninvasive diagnostic imaging agent according to claim ₁ , wherein X1 in the formula (1) is a halogen atom.
5. The noninvasive diagnostic imaging agent according to any one of claims 1 to 4, for use in positron emission tomography.
6. The noninvasive diagnostic imaging agent according to any one of claims 1 to 5, wherein the heart disease is an ischemic heart disease.
7. The non-invasive diagnostic imaging agent according to claim 6, wherein the ischemic heart disease is coronary heart disease angina, myocardial infarction, acute coronary syndrome or ischemic heart failure.
8. The noninvasive diagnostic imaging agent according to any one of claims 1 to 5, wherein the heart disease is a non-ischemic heart disease.
9. The noninvasive diagnostic imaging agent according to claim 8, wherein the non-ischemic heart disease is myocarditis, hypertensive heart disease, dilated cardiomyopathy, hypertrophic cardiomyopathy or non-ischemic heart failure.

Images