Novel compound, alpha-synuclein aggregate binder, and use thereof

Abstract

The present invention relates to a compound represented by formula (I) or (II), a pharmaceutically acceptable salt of the compound, or a solvate of the compound or the pharmaceutically acceptable salt.

Description

M: molar concentration DMSO-d6: deuterated dimethyl sulfoxide 1H NMR: proton nuclear magnetic resonance DIEA: N-ethyl-N-isopropylpropan-2-amine DMF: N,N-dimethylformamide (herein, also referred to as "dimethylformamide") THF: tetrahydrofuran MeOH: methanol EtOH: ethanol DMSO: dimethyl sulfoxide TEA: triethylamine TFA: trifluoroacetic acid

[0139] Reference Example 1 : production of di-tert-butyl (5- iodopyrazin-2-yl)-2-imidodicarbonate

[0140] To a solution of 5-iodopyrazin-2-amine (CAS [886860-50-0]) (10.5 g) in THF (100 ml) were added a solution of di-tert-butyl dicarbonate (25.9 g) in THF (50 ml) and N,N-dimethylpyridin-4-amine (1.45 g) at 0°C. The mixture was stirred at 0°C to room temperature overnight, and diluted with water and ethyl acetate. The insoluble was removed by filtration and the filtrate was extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, passed through a short silica gel column, and concentrated under reduced pressure to obtain the title compound (18.8 g) as a brown solid. 1H NMR (300 MHz, DMSO-d6) 6 1.37-1.41 (18H, m), 8.65 (1H, d, J=1.3 Hz), 8.90 (1H, d, J=1.5 Hz)

[0141] Reference Example 2: production of tert-butyl (5-iodopyrazin-2-yl)carbamate

[0142] / = N   Boc 1-¾ N --------*- I— / )“NH Boc                               Boc To a solution of di-tert-butyl (5-iodopyrazin-2-yl)-2- imidodicarbonate (18.8 g) produced in Reference Example 1 in MeOH (200 ml), was added potassium carbonate (7.40 g) at room temperature. The mixture was stirred at room temperature for 2 h, concentrated to approximately a 5 quarter volume under reduced pressure, cooled to 0°C, neutralized with 5% citric acid solution, and diluted with water. The precipitated solid was collected by filtration, washed with water, and dried to obtain the title compound (13.7 g) as a brown solid. 10      1H NMR (300 MHz, DMSO-d6) 6 1.47 (9H, s), 8.55 (1H, d, J=1.3 Hz), 8.87 (1H, d, J=1.5 Hz), 10.29 (1H, brs)

[0143] Reference Example 3: production of tert-butyl (5-iodopyrazin-2-yl)(methyl)carbamate 15

[0144] To a solution of tert-butyl (5-iodopyrazin-2- yl)carbamate (13.7 g) produced in Reference Example 2 and cesium carbonate (20.9 g) in DMF (85 ml), was added methyl iodide (3.45 ml) at 0°C. The mixture was stirred at 0°C to room temperature overnight, cooled to 0°C, and diluted with water. The precipitated solid was collected by filtration, washed with water, and dried to obtain the title compound (13.0 g) as a beige solid. 1H NMR (300 MHz, DMSO-d6) 6 1.49 (9H, s), 3.27 (3H, s), 8.72 (1H, d, J=1.5 Hz), 8.83 (1H, d, J=1.5 Hz)

[0145] Reference Example 4: production of tert-butyl (5-(3-hydroxyprop-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate

[0146] To a solution of tert-butyl (5-iodopyrazin-2-yl)(methyl)carbamate (13.0 g) produced in Reference Example 3, 2-propyn-1-ol (3.43 ml), and copper iodide (I) (739 mg) in TEA (27 ml) and THF (27 ml), was added dichlorobis(triphenylphosphine)palladium (II) (545 mg) at room temperature under nitrogen atmosphere. The mixture was stirred at room temperature for 2 h, diluted with ethyl acetate, and filtered through a celite pad. The filtrate was concentrated under reduced pressure. The residue was diluted with ethyl acetate, acidified with 5% citric acid solution, filtered through a celite pad, and extracted with 5 ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, passed through a silica gel pad, and concentrated under reduced pressure to obtain the title compound (10.2 g) as a brown solid. 10      1H NMR (300 MHz, DMSO-d6) 6 1.50 (9H, s), 3.31 (3H, s), 4.35 (2H, d, J=6.0 Hz), 5.48 (1H, t, J=6.0 Hz), 8.52 (1H, d, J=1.5 Hz), 8.98 (1H, d, J=1.5 Hz)

[0147] Reference Example 5: production of tert-butyl (5-(3 15      hydroxyprop-1-yn-1-yl)pyrimidin-2-yl)(methyl)carbamate

[0148] The title compound (195 mg) was obtained as a brown solid, in a manner similar to that in Reference Example 4 with use of tert-butyl (5-iodopyrimidin-2-yl)(methyl)carbamate (CAS [1578264-18-2]) (250 mg). 1H NMR (300 MHz, DMSO-d6) 6 1.44 (9H, s), 3.31 (3H, s), 4.34 (2H, d, J=5.7 Hz), 5.44 (1H, t, J=5.8 Hz), 8.77(2H, s)

[0149] Reference Example 6: production of tert-butyl methyl(5-(3-oxoprop-1-yn-1-yl)pyrazin-2-yl)carbamate

[0150] To a solution of tert-butyl(5-(3-hydroxyprop-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (10.4 g) produced in Reference Example 4 in acetonitrile (200 ml) was added 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3-(1H)-one (20.1 g) at room temperature. The mixture was stirred at room temperature for 2 h and cooled to 0°C. To the mixture were added saturated sodium thiosulfate solution and 5% sodium bicarbonate solution. The mixture was stirred for 5 min and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, passed through a short silica gel column, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl 5 acetate) to obtain the title compound (6.20 g) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.52 (9H, s), 3.35 (3H, s), 8.82 (1H, d, J=1.3 Hz), 9.17 (1H, d, J=1.5 Hz), 9.48(1H, s) 10

[0151] Reference Example 7: production of tert-butyl methyl(5-(3-oxoprop-1-yn-1-yl)pyrimidin-2-yl)carbamate

[0152] 15            The title compound (149 mg) was obtained as a white solid, in a manner similar to that in Reference Example 6 with use of tert-butyl (5-(3-hydroxyprop-1-yn-1-yl)pyrimidin-2-yl)(methyl)carbamate (190 mg) produced in Reference Example 5. 1H NMR (300 MHz, DMSO-d6) 6 1.47 (9H, s), 3.36 (3H, s), 9.00 (2H, s), 9.46 (1H, s)

[0153] Reference Example 8: production of 2-((1- (benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H-pyrane

[0154] F y 0Bzl OH F y OBzl OTHP To a solution of 1-(benzyloxy)-3-fluoropropan-2-ol (CAS [112482-36-7]) (6.37 g) and 3,4-dihydro-2H-pyrane (3.75 ml) in THF (67 ml), was added p-toluenesulfonic acid monohydrate (132 mg) at room temperature. The mixture was stirred at room temperature overnight. DIEA (0.242 ml) was added to the mixture. The mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate) to obtain the title compound (8.37 g) as a colorless oil. 1H NMR (300 MHz, DMSO-d6) 6 1.35-1.54 (4H, m), 1.56- 1.80 (2H, m), 3.36-3.47 (1H, m), 3.48-3.63 (2H, m), 3.80 (1H, ddd, J=11.2, 7.9, 3.4 Hz), 3.90-4.06 (1H, m), 4.35- 4.70 (2H, m), 4.51 (2H, d, J=2.1 Hz), 4.74-4.81 (1H, m), 7.24-7.41 (5H, m)

[0155] Reference Example 9: production of 2-(((R)-1- (benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H- 10 15 pyrane

[0156] F'^Y^'OSzl -------► F^^V^OBzl OH                          OTHP The title compound (10.36 g) was obtained as a colorless oil, in a manner similar to that in Reference Example 8 with use of (R)-1-(benzyloxy)-3-fluoropropan-2-ol (CAS [147332-34-1]) (7.85 g). 1H NMR (300 MHz, DMSO-d6) 6 1.47 (4H, br dd, J = 7.4, 3.9 Hz), 1.56-1.80 (2H, m), 3.35-3.47 (1H, m), 3.47-3.63 (2H, m), 3.80 (1H, ddd, J=11.3, 8.0, 3.4 Hz), 3.89-4.11 (1H, m), 4.34-4.69 (4H, m), 4.73-4.83 (1H, m), 7.19-7.49 (5H, m)

[0157] Reference Example 10: production of 2-(((S)-1-(benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H-pyrane 5

[0158] F^V^OBzl -------► F'^^'OBzl OH                          OTHP The title compound (10.48 g) was obtained as a colorless oil, in a manner similar to that in Reference Example 8 with use of (S)-1-(benzyloxy)-3-fluoropropan-10       2-ol (CAS [1707146-21-1]) (7.55 g). 1H NMR (300 MHz, DMSO-d6) 6 1.47 (4H, br dd, J = 7.4, 3.9 Hz), 1.56-1.79 (2H, m), 3.35-3.47 (1H, m), 3.48-3.62 (2H, m), 3.80 (1H, ddd, J=11.2, 7.9, 3.3 Hz), 3.90-4.08 (1H, m), 4.35-4.70 (4H, m), 4.73-4.81 (1H, m), 7.24-7.42 (5H, 15 m)

[0159] Reference Example 11: production of 3-(benzyloxy)- 2-((tert-butyldimethylsilyl)oxy)propyl                   4- methylbenzenesulfonate

[0160] TsO OBzl TsO OBzl OTBS To a solution of 3-(benzyloxy)-2-hydroxypropyl 4-methylbenzenesulfonate (CAS [99881-48-8]) (2.80 g) and 1H-imidazole (737 mg) in DMF (30 ml), was added tertbutyldimethylchlorosilane (1.51 g) at 0°C. The mixture was stirred at room temperature overnight, cooled to 0°C, diluted with water and ethyl acetate, acidified to pH approximately 5 with 5% citric acid solution, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate) to obtain the title compound (3.37 g) as a colorless oil. 1H NMR (300 MHz, DMSO-d6) 6 -0.02 (6H, d, J = 1.1 Hz), 0.79 (9H, s), 2.41 (3H, s), 3.36 (2H, d, J=5.3 Hz), 3.864.05 (3H, m), 4.43 (2H, s), 7.20-7.39 (5H, m), 7.47 (2H, d, J=8.1 Hz), 7.77 (2H, d, J=8.3 Hz)

[0161] Reference Example 12: production of 3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol

[0162] F y^O Bzl --------     F '^Y^'0 H OTHP                         OTHP A mixture of 2-((1-(benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H-pyrane (8.30 g) produced in Reference Example 8, 10% palladium-carbon (containing 50% water, 1.98 g) and EtOH (85 ml) was stirred at room temperature overnight under hydrogen atmosphere at ambient pressure. The catalyst was removed by filtration. The filtrate was concentrated under reduced pressure to obtain the title compound (5.45 g) as a colorless oil. 1H NMR (300 MHz, DMSO-d6) 6 1.33-1.55 (4H, m), 1.561.86 (2H, m), 3.36-3.58 (3H, m), 3.68-3.88 (2H, m), 4.314.70 (2H, m), 4.71-4.86 (2H, m)

[0163] Reference Example 13: production of (2R)-3-fluoro- 2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol

[0164] F^Y^OBzl ------► F'^Y^OH □TUP                         OTHP The title compound (6.85 g) was obtained as a colorless oil, in a manner similar to that in Reference Example 12 with use of 2-(((R)-1-(benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H-pyrane (10.35 g) produced in Reference Example 9. 1H NMR (300 MHz, DMSO-d6) 6 1.35-1.53 (4H, m), 1.551.81 (2H, m), 3.37-3.62 (3H, m), 3.67-3.91 (2H, m), 4.294.69 (2H, m), 4.71-4.87 (2H, m)

[0165] Reference Example 14: production of (2S)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol

[0166] F "      OBzl OTHP F V OH OTHP The title compound (6.90 g) was obtained as a colorless oil, in a manner similar to that in Reference 10 Example 12 with use of 2-(((S)-1-(benzyloxy)-3-fluoropropan-2-yl)oxy)tetrahydro-2H-pyrane (10.45 g) produced in Reference Example 10. 1H NMR (300 MHz, DMSO-d6) 6 1.33-1.56 (4H, m), 1.57 1.81 (2H, m), 3.35-3.59 (3H, m), 3.69-3.90 (2H, m), 4.31 4.68 (2H, m), 4.71-4.87 (2H, m)

[0167] Reference Example 15: production of 2-((tert-butyldimethylsilyl)oxy)-3-hydroxypropyl                4- methylbenzenesulfonate

[0168] 15 The title compound (2.66 g) was obtained as a colorless oil, in a manner similar to that in Reference Example 12 with use of 3-(benzyloxy)-2-((tert-butyldimethylsilyl)oxy)propyl 4-methylbenzenesulfonate (3.36 g) produced in Reference Example 11. 1H NMR (300 MHz, DMSO-d6) 6 -0.01 (3H, s), 0.01 (3H, s), 0.80 (9H, s), 2.42 (3H, s), 3.20-3.38 (2H, m), 3.75-3.91 (2H, m), 4.02-4.10 (1H, m), 4.81 (1H, t, J=5.6Hz), 7.49 (2H, dd, J=8.6, 0.7 Hz), 7.77 (2H, d, J=8.3 Hz)

[0169] Reference Example 16: production of mixture of (2S)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol and     (2S)-1-fluoro-3-((tetrahydro-2H-pyran-2- yl)oxy)propan-2-ol

[0170] F^V^OH ------► F^Y^OH      F'^Y^OTHP OTHP                        OTHP              OH The title mixture of compounds (6.90 g) was obtained as a colorless oil by storing (2S)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol    (6.90 g) produced in Reference Example 14 at room temperature. 1H NMR (300 MHz, DMSO-d6) 6 1.33-1.54 (4H, m), 1.561.85 (2H, m), 3.28-3.96 (5H, m), 4.18-4.92 (3H, m), 4.925.20 (1H, m)

[0171] Reference Example 17: production of diethyl ((6- ((tert-butyldimethylsilyl)oxy)benzo[d]thiazol-2- yl)methyl)phosphonate

[0172] A mixture of 2-(bromomethyl)-6-((tert- 10 15 butyldimethylsilyl)oxy)benzo[d]thiazole (CAS [163868565-0]) (3.06 g) and triethyl phosphite (1.78 ml) was stirred at 100°C for 3 h, cooled to room temperature, and purified by silica gel column chromatography (ethyl acetate / methanol) to obtain the title compound (2.39 g) as a yellow oil. 1H NMR (300 MHz, DMSO-d6) 6 0.22 (6H, s), 0.97 (9H, s), 1.23 (6H, t, J=7.0 Hz), 3.80-3.92 (2H, m), 4.01-4.13 (4H, m), 7.00 (1H, dd, J=8.7, 2.5 Hz), 7.56 (1H, d, J=2.4 Hz), 7.81 (1H, d, J=8.8 Hz)

[0173] Reference Example 18: production of diethyl ((6-hydroxybenzo[d]thiazol-2-yl)methyl)phosphonate To a solution of diethyl ((6-((tert butyldimethylsilyl)oxy)benzo[d]thiazol-2- yl)methyl)phosphonate (4.87 g) produced in Reference Example 17 in THF (50 ml), was added tetra-n-butylammonium fluoride (1M THF solution, 12.9 ml) at room temperature. The mixture was stirred at room 10 15 temperature for 1 h, diluted with water, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residual solid was suspended in hexane / ethyl acetate, collected by filtration, washed with hexane / ethyl acetate, and dried to obtain the title compound (2.85 g) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.22 (6H, t, J = 7.1 Hz), 3.81 (2H, d, J=21.4 Hz), 4.05 (4H, dq, J=8.3, 7.1 Hz), 6.93 (1H, dd, J=8.8, 2.5 Hz), 7.34 (1H, d, J=2.4 Hz), 7.73 (1H, d, J=8.8 Hz), 9.78 (1H, brs)

[0175] Reference Example 19: production of diethyl ((6-(3- fluoro-2-((tetrahydro-2H-pyran-2- yl)oxy)propoxy)benzo[d]thiazol-2-yl)methyl)phosphonate

[0176] 10 15 To a solution of diethyl ((6-hydroxybenzo[d]thiazol-2-yl)methyl)phosphonate (2.84 g) produced in Reference Example 18,     3-fluoro-2-((tetrahydro-2H-pyran-2- yl)oxy)propan-1-ol (2.52 g) produced in Reference Example 12, and triphenylphosphine (4.20 g) in THF (50 ml), was added diisopropyl azodicarboxylate (3.15 ml) at room temperature. The mixture was stirred at room temperature for 1 day. Then, 3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol (0.504 g) produced in Reference Example 12, triphenylphosphine (0.742 g), and diisopropyl azodicarboxylate (0.555 ml) were added to the mixture at room temperature. The mixture was stirred at room temperature overnight, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate) to obtain the title compound (3.78 g) as a yellow oil. 1H NMR (300 MHz, DMSO-d6) 6 1.22 (6H, t, J = 7.0 Hz), 1.37 -1.56 (4H, m), 1.59-1.80 (2H, m), 3.41-3.53 (1H, m), 3.783.94 (3H, m), 4.01-4.11 (4H, m), 4.12-4.29 (3H, m), 4.484.65 (1H, m), 4.65-4.81 (1H, m), 4.83-4.94 (1H, m), 7.12 (1H, dt, J=9.0, 2.1 Hz), 7.70 (1H, d, J=2.4 Hz), 7.84 (1H, d, J=8.9 Hz)

[0177] Reference Example 20: production of tert-butyl (E)-(5-(4-(6-(3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate

[0178] To a solution of diethyl ((6-(3-fluoro-2-((tetrahydro- 2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol-2- yl)methyl)phosphonate (3.77 g) produced in Reference Example 19 and tert-butyl methyl(5-(3-oxoprop-1-yn-1-yl)pyrazin-2-yl)carbamate (2.56 g) produced in Reference Example 6 in THF (30 ml), was added sodium hydride (60% in oil, 392 mg) at 0°C. The mixture was stirred at 0°C for 10 min. DMF (30 ml) was added to the mixture at 0°C. The mixture was stirred at 0°C to room temperature for 3 h. Tert-butyl      methyl(5-(3-oxoprop-1-yn-1-yl)pyrazin-2- yl)carbamate (256 mg) produced in Reference Example 6 was added to the mixture at room temperature. The mixture was stirred at room temperature for 1 h, diluted with ethyl acetate and water, neutralized with 5% citric acid solution, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate). The fractions containing the desired compound were concentrated under reduced pressure. The residual solid was suspended in hexane, collected by filtration, washed with hexane, and dried to obtain the title compound (2.06 g) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.39-1.58 (13H, m), 1.591.81 (2H, m), 3.33 (3H, s), 3.41-3.52 (1H, m), 3.78-3.95 5      (1H, m), 4.13-4.31 (3H, m), 4.48-4.66 (1H, m), 4.66-4.83 (1H, m), 4.84-4.93 (1H, m), 7.01 (1H, d, J=16.2 Hz), 7.17 (1H, dt, J=9.0, 2.2 Hz), 7.48 (1H, d, J=16.0 Hz), 7.77 (1H, d, J=2.4 Hz), 7.92 (1H, d, J=8.9 Hz), 8.65 (1H, d, J=1.5 Hz), 9.06 (1H, d, J=1.5 Hz) 10

[0179] Example 1: production of tert-butyl (E)-(5-(4-(6-hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate

[0180] 15 To a solution of diethyl     ((6-((tert- butyldimethylsilyl)oxy)benzo[d]thiazol-2- yl)methyl)phosphonate (2.39 g) produced in Reference Example 17 and tert-butyl methyl(5-(3-oxoprop-1-yn-1-yl)pyrazin-2-yl)carbamate (1.65 g) produced in Reference Example 6 in THF (25 ml), was added sodium hydride (60% in oil, 322 mg) at 0°C. The mixture was stirred at 0°C for 5 min. DMF (25 ml) was added to the mixture at 0°C. The mixture was stirred at 0°C for 2 h. Sodium hydride (60% in oil, 138 mg) and tert-butyl methyl(5-(3-oxoprop-1-yn-1-yl)pyrazin-2-yl)carbamate (601 mg) produced in Reference Example 6 were added to the mixture at 0°C. The mixture was stirred at 0°C to room temperature for 2 h, cooled to 0°C, acidified to pH approximately 5 with 5% citric acid solution, diluted with water, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, passed through a short silica gel column, and concentrated under reduced pressure. The residual solid was suspended in ethyl acetate / hexane, collected by filtration, washed with ethyl acetate / hexane, and dried to obtain the title compound (1.85 g) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.51 (9H, s), 3.33 (3H, s), 6.94 (1H, d, J=16.0 Hz), 7.00 (1H, dd, J=8.9, 2.4 Hz), 7.39 (1H, d, J=2.3 Hz), 7.44 (1H, d, J=16.0 Hz), 7.82 (1H, d, J=8.9 Hz), 8.64 (1H, d, J=1.5 Hz), 9.05 (1H, d, J=1.5 Hz), 5       10.14 (1H, brs)

[0181] Example 2: production of tert-butyl (E)-(5-(4-(6-hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1- yl)pyrimidin-2-yl)(methyl)carbamate 10

[0182] The title compound (101 mg) was obtained as a yellow solid, in a manner similar to that in Example 1 with use             of             diethyl             ((6-((tert- 15 butyldimethylsilyl)oxy)benzo[d]thiazol-2- yl)methyl)phosphonate (254 mg) produced in Reference Example 17 and tert-butyl methyl(5-(3-oxoprop-1-yn-1- yl)pyrimidin-2-yl)carbamate (145 mg) produced in Reference Example 7. 1H NMR (300 MHz, DMSO-d6) 6 1.46 (9H, s), 3.34 (3H, s), 6.92 (1H, d, J=16.0 Hz), 7.00 (1H, dd, J=8.9, 2.4 Hz), 7.38 (1H, d, J=16.0 Hz), 7.39 (1H, d, J=2.4 Hz), 7.82 (1H, d, 5       J=8.9 Hz), 8.87 (2H, s), 10.01 (1H, s)

[0183] Reference Example 21: production of tert-butyl (5-((E)-4-(6-((2R)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1- 10 yl)pyrazin-2-yl)(methyl)carbamate

[0184] The title compound (100 mg) was obtained as a paleyellow solid, in a manner similar to that in Reference 15 Example 19 with use of tert-butyl (E)-(5-(4-(6- hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin- 2-yl)(methyl)carbamate (100 mg) produced in Example 1, 10 15 (2R)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol (114 mg) produced in Reference Example 13, and bis(2-methoxyethyl) azodicarboxylate (172 mg). 1H NMR (300 MHz, DMSO-d6) 6 1.51 (13H, s), 1.60-1.79 (2H, m), 3.34 (3H, s), 3.42-3.54 (1H, m), 3.79-3.96 (1H, m), 4.14-4.31 (3H, m), 4.49-4.82 (2H, m), 4.84-4.96 (1H, m), 7.02 (1H, d, J=16.1 Hz), 7.17 (1H, dt, J=9.0, 2.1 Hz), 7.48 (1H, d, J=16.1 Hz), 7.77 (1H, d, J=2.5 Hz), 7.92 (1H, d, J=9.0 Hz), 8.65 (1H, d, J=1.4 Hz), 9.06 (1H, d, J=1.5 Hz)

[0185] Reference Example 22: production of tert-butyl (5-((E)-4-(6-((2S)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate

[0186] The title compound (22 mg) was obtained as a paleyellow solid, in a manner similar to that in Reference Example 19 with use of tert-butyl (E)-(5-(4-(6-hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (100 mg) produced in Example 1, a mixture (114 mg) of (2S)-3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propan-1-ol and (2S)-1-fluoro-3-((tetrahydro-2H-pyran-2-yl)oxy)propan-2-ol produced in Reference Example 16, and bis(2-methoxyethyl) azodicarboxylate (172 mg). 1H NMR (300 MHz, DMSO-d6) 6 1.51 (13H, s), 1.60-1.79 (2H, m), 3.34 (3H, s), 3.42-3.54 (1H, m), 3.79-3.95 (1H, m), 4.13-4.30 (3H, m), 4.49-4.82 (2H, m), 4.84-4.96 (1H, m), 7.02 (1H, d, J=16.2 Hz), 7.17 (1H, dd, J=8.8, 2.4 Hz), 7.48 (1H, d, J=16.0 Hz), 7.77 (1H, d, J=2.3 Hz), 7.92 (1H, d, J=9.0 Hz), 8.65 (1H, d, J=1.3 Hz), 9.06 (1H, d, J=1.3 Hz)

[0187] Reference Example 23: production of (E)-3-((2-(4- (5-((tert-butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but- 1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-((tert- butyldimethylsilyl)oxy)propyl 4-methylbenzenesulfonate

[0188] 10 15 The title compound (1.47 g) was obtained as a paleyellow solid, in a manner similar to that in Reference Example 19 with use of tert-butyl (E)-(5-(4-(6-hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (971 mg) produced in Example 1, 2-((tert-butyldimethylsilyl)oxy)-3-hydroxypropyl        4- methylbenzenesulfonate (1.11 g) produced in Reference Example 15, and bis(2-methoxyethyl) azodicarboxylate (835 mg). 1H NMR (300 MHz, DMSO-d6) 6 0.04 (3H, s), 0.04 (3H, s), 0.81 (9H, s), 1.51 (9H, s), 2.38 (3H, s), 3.34 (3H, s), 3.904.19 (4H, m), 4.20-4.32 (1H, m), 7.02 (1H, d, J=16.0 Hz), 7.02-7.08 (1H, m), 7.45 (2H, brd, J=8.1 Hz), 7.48 (1H, brd, J=16.0 Hz), 7.66 (1H, d, J=2.3 Hz), 7.79 (2H, d, J=8.3 Hz), 7.91 (1H, d, J=9.0 Hz), 8.65 (1H, d, J=1.5 Hz), 9.06 (1H, d, J=1.5 Hz)

[0189] Reference Example 24: production of tert-butyl (E)-(5-(4-(6-(3-fluoro-2-hydroxypropoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrimidin-2-yl)(methyl)carbamate

[0190] 10 15 To a solution of   tert-butyl    (E)-(5-(4-(6- hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1- yl)pyrimidin-2-yl)(methyl)carbamate (99 mg) produced in Example 2 and potassium carbonate (66 mg) in DMF (3 ml), was added 2-(fluoromethyl)oxirane (CAS [503-09-3]) (0.060 ml) at room temperature. The mixture was heated at 80°C for 4 h, cooled to room temperature, diluted with water and ethyl acetate, neutralized with 5% citric acid solution, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography 5 (hexane / ethyl acetate) to obtain the title compound (36 mg) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.46 (9H, s), 3.34 (3H, s), 4.02-4.16 (3H, m), 4.39-4.46 (1H, m), 4.56-4.63 (1H, m), 5.49(1H, d, J=5.3 Hz), 6.99 (1H, d, J=16.2 Hz), 7.16 (1H, 10 dd, J=9.0, 2.6 Hz), 7.41 (1H, d, J =16.2 Hz), 7.73 (1H, d, J=2.3 Hz), 7.91 (1H, d, J=9.0 Hz), 8.87(2H, s)

[0191] Reference Example 25: production of (E)-3-((2-(4-(5-((tert-butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but- 15       1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2- hydroxypropyl 4-methylbenzenesulfonate

[0192] OTBS                                                  OH To solution of     (E)-3-((2-(4-(5-((tert- butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-((tert- butyldimethylsilyl)oxy)propyl 4-methylbenzenesulfonate (100 mg) produced in Reference Example 23 and acetic acid (0.023 ml) in THF (10 ml) was added tetra-n-butylammonium fluoride (1M THF solution, 0.533 ml) at 0°C. The mixture was stirred at 0°C for 0.5 h, diluted with water, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate) to obtain the title compound (37 mg) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.51 (9H, s), 2.35 (3H, s), 3.34 (3H, s), 3.91-4.19 (5H, m), 5.59 (1H, d, J=4.9 Hz), 7.02 (1H, d, J=16.1 Hz), 7.00-7.07 (1H, m), 7.35-7.43 (2H, m), 7.48 (1H, d, J=16.1 Hz), 7.62 (1H, d, J=2.5 Hz), 7.77 (2H, d, J=8.3 Hz), 7.89 (1H, d, J=9.0 Hz), 8.65 (1H, d, J=1.5 Hz), 9.06 (1H, d, J=1.5 Hz)

[0193] Reference Example 26: production of (E)-2-hydroxy- 3-((2-(4-(5-(methylamino)pyrazin-2-yl)but-1-en-3-yn-1- yl)benzo[d]thiazol-6-yl)oxy)propyl                       4- methylbenzenesulfonate

[0194] OTBS                                                  OH A solution of       (E)-3-((2-(4-(5-((tert- butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-((tert-butyldimethylsilyl)oxy)propyl   4-methylbenzenesulfonate (750 mg) produced in Reference Example 23 in TFA (13.5 ml) and water (1.5 ml) was stirred at room temperature for 0.5 h, cooled to 0°C, diluted with ethyl acetate, neutralized with saturated sodium bicarbonate solution, and extracted with ethyl acetate. The extract was washed with water and brine. The solid precipitated from the extract was collected by filtration. The filtrate was dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The residual solid and the solid collected by the filtration were combined and suspended in hexane, collected by filtration, washed with hexane, and dried to obtain the title compound (550 mg) as a yellow solid. 1H NMR (400 MHz, DMSO-d6) 6 2.34 (3H, s), 2.84 (3H, d, 5      J=4.8 Hz), 3.90-3.98 (2H, m), 4.02-4.17 (3H, m), 5.60 (1H, d, J=4.8 Hz), 6.95 (1H, d, J=16.0 Hz), 7.00 (1H, dd, J=8.8, 2.4 Hz), 7.29 (1H, d, J=16.0 Hz), 7.40 (2H, d, J=8.0 Hz), 7.59 (1H, d, J=2.4 Hz), 7.68 (1H, brs), 7.77 (2H, d, J=8.4 Hz), 7.86 (1H, d, J=8.8 Hz), 7.94 (1H, d, J=1.6 Hz), 10      8.21 (1H, d, J=1.2 Hz)

[0195] Example 3:     production of    (E)-2-(4-(5- (methylamino)pyrazin-2-yl)but-1-en-3-yn-1- yl)benzo[d]thiazol-6-ol 15

[0196] A solution of     tert-butyl     (E)-(5-(4-(6- hydroxybenzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin- 2-yl)(methyl)carbamate (230 mg) produced in Example 1 in TFA (4 ml) was stirred at room temperature for 1 h, and concentrated under reduced pressure. Ethyl acetate was added to the residue. The mixture was cooled to 0°C, neutralized with saturated sodium bicarbonate solution, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residual solid was suspended in ethyl acetate, collected by filtration, washed with ethyl acetate, and dried to obtain the title compound (140 mg) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 2.84 (3H, d, J = 4.9 Hz), 6.81-6.92 (1H, m), 6.98 (1H, dd, J=8.8, 2.4 Hz), 7.26 (1H, d, J=15.8 Hz), 7.37 (1H, d, J=2.3 Hz), 7.63 (1H, q, J=5.0 Hz), 7.79 (1H, d, J=8.7 Hz), 7.94 (1H, d, J=1.5 Hz), 8.20 (1H, d, J=1.1 Hz), 9.97(1H, s)

[0197] Example 4: production of (E)-1-fluoro-3-((2-(4-(5-(methylamino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol (hereinafter referred to as "SPAL-T-06")

[0198] OTHP                                                 OH A solution of tert-butyl (E)-(5-(4-(6-(3-fluoro-2-((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol- 5      2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (2.06 g) produced in Reference Example 20 in TFA (20 ml) was stirred at room temperature for 0.5 h and concentrated under reduced pressure. Toluene was added to the residue. The mixture was concentrated under reduced pressure. 10 Then, ethyl acetate and water were added to the residue. The mixture was neutralized with 5% sodium bicarbonate solution. The precipitated solid was collected by filtration, washed with water and ethyl acetate, and dried. The filtrate and the washing liquid were combined and 15 extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residual solid was suspended in ethyl acetate, collected by filtration, washed with ethyl acetate, and dried. This solid and the solid obtained before the extraction were combined, suspended in ethyl acetate, collected by filtration, washed with ethyl acetate, and dried to obtain the title compound (1.07 g) as a yellow solid. 5      1H NMR (300 MHz, DMSO-d6) 6 2.84 (3H, d, J = 4.9 Hz), 4.00-4.16 (3H, m), 4.37-4.49 (1H, m), 4.53-4.66 (1H, m), 5.51 (1H, d, J=5.1 Hz), 6.95 (1H, d, J=16.0 Hz), 7.15 (1H, dd, J=9.0, 2.6 Hz), 7.29 (1H, d, J=16.0 Hz), 7.67 (1H, q, J=4.6 Hz), 7.71 (1H, d, J=2.6 Hz), 7.89 (1H, d, J=9.0 Hz), 10       7.94 (1H, d, J=1.5 Hz), 8.21 (1H, d, J=1.3 Hz)

[0199] Example 5: production of (R,E)-1-fluoro-3-((2-(4-(5-(methylamino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol 15

[0200] The title compound (58 mg) was obtained as a pale yellow solid, in a manner similar to that in Example 4 with use of tert-butyl (5-((E)-4-(6-((2R)-3-fluoro-2- ((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (98 mg) produced in Reference Example 21. 1H NMR (300 MHz, DMSO-d6) 6 2.84 (3H, d, J = 4.8 Hz), 4.01-4.17 (3H, m), 4.37-4.49 (1H, m), 4.53-4.65 (1H, m), 5.50 (1H, d, J=5.1 Hz), 6.95 (1H, d, J=16.1 Hz), 7.15 (1H, dd, J=8.9, 2.6 Hz), 7.29 (1H, d, J=16.1 Hz), 7.66 (1H, q, J=4.9 Hz), 7.71(1H, d, J=2.5 Hz), 7.89 (1H, d, J=9.0 Hz), 7.94 (1H, d, J=1.4 Hz), 8.21(1H, d, J=1.3 Hz)

[0201] Example 6: production of (S,E)-1-fluoro-3-((2-(4-(5-(methylamino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol

[0202] OTHP                                                 OH The title compound (12 mg) was obtained as a pale yellow solid, in a manner similar to that in Example 4 with use of tert-butyl (5-((E)-4-(6-((2S)-3-fluoro-2- ((tetrahydro-2H-pyran-2-yl)oxy)propoxy)benzo[d]thiazol- 10 2-yl)but-3-en-1-yn-1-yl)pyrazin-2-yl)(methyl)carbamate (20 mg) produced in Reference Example 22. 1H NMR (300 MHz, DMSO-d6) 6 2.84 (3H, d, J = 4.7 Hz), 4.00-4.17 (3H, m), 4.37-4.49 (1H, m), 4.53-4.65 (1H, m), 5.51 (1H, d, J=4.7 Hz), 6.95 (1H, d, J=16.0 Hz), 7.15 (1H, dd, J=8.9, 2.5 Hz), 7.29 (1H, d, J=16.2 Hz), 7.62-7.70 (1H, m), 7.71 (1H, d, J=2.4 Hz), 7.89 (1H, d, J=8.9 Hz), 7.94 (1H, d, J=1.3 Hz), 8.21 (1H, d, J=1.1 Hz)

[0203] Example 7: production of (E)-1-fluoro-3-((2-(4-(2-(methylamino)pyrimidin-5-yl)but-1-en-3-yn-1- yl)benzo[d]thiazol-6-yl)oxy)propan-2-ol       (hereinafter referred to as "SPAL-T-05")

[0204] 15 The title compound (15 mg) was obtained as a yellow solid, in a manner similar to that in Example 4 with use of tert-butyl                             (E)-(5-(4-(6-(3-fluoro-2- hydroxypropoxy)benzo[d]thiazol-2-yl)but-3-en-1-yn-1- yl)pyrimidin-2-yl)(methyl)carbamate (34 mg) produced in Reference Example 24. 1H NMR (300 MHz, DMSO-d6) 6 2.84 (3H, d, J = 4.5 Hz), 4.00-4.16 (3H, m), 4.36-4.50 (1H, m), 4.52-4.66 (1H, m), 5       5.49 (1H, d, J=5.3 Hz), 6.86-6.99 (1H, m), 7.10-7.18 (1H, m), 7.25 (1H, d, J=15.8 Hz), 7.67-7.77 (2H, m), 7.88 (1H, d, J=9.0 Hz), 8.38-8.58 (2H, m)

[0205] Example 8: production of (E)-3-((2-(4-(5-((tert- 10      butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but-1-en-3- yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-((tetrahydro-2H-pyran-2-yl)oxy)propyl 4-methylbenzenesulfonate

[0206] OH                                                  OTHP 15               To a solution of     (E)-3-((2-(4-(5-((tert- butoxycarbonyl)(methyl)amino)pyrazin-2-yl)but-1-en-3- yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-hydroxypropyl 4- methylbenzenesulfonate (35 mg) produced in Reference Example 25 and 3,4-dihydro-2H-pyrane (0.050 ml) in THF (15 ml), was added p-toluenesulfonic acid monohydrate (21 mg) at room temperature. The mixture was stirred at room temperature for 4 h. Then, 3,4-dihydro-2H-pyrane (0.249 ml) and p-toluenesulfonic acid monohydrate (21 mg) were added to the mixture at room temperature. The mixture was stirred at room temperature overnight, diluted with ethyl acetate, neutralized with 5% sodium bicarbonate solution, diluted with water, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate). The desired fractions containing the desired compound were concentrated under reduced pressure. The residual solid was suspended in hexane, collected by filtration, washed with hexane, and dried to obtain the title compound (28 mg) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.32-1.72 (15H, m), 2.35 (3H, s), 3.34-3.46 (4H, m), 3.61-3.93 (1H, m), 4.01-4.41 (5H, m), 4.66-4.90 (1H, m), 6.99-7.05 (1H, m), 7.02-7.09 (1H, m), 7.41 (2H, brd, J=8.1 Hz), 7.48 (1H, d, J=16.2 Hz), 7.65 (1H, d, J=2.1 Hz), 7.79 (2H, brd, J=7.3 Hz), 7.90 (1H, d, J=8.9 Hz), 8.65 (1H, d, J=1.1 Hz), 9.06 (1H, d, J=0.9 Hz). 5

[0207] Example 9: production of (E)-3-((2-(4-(5- (methylamino)pyrazin-2-yl)but-1-en-3-yn-1- yl)benzo[d]thiazol-6-yl)oxy)-2-((tetrahydro-2H-pyran-2- yl)oxy)propyl 4-methylbenzenesulfonate 10

[0208] OH                                                    OTHP To a solution of   (E)-2-hydroxy-3-((2-(4-(5- (methylamino)pyrazin-2-yl)but-1-en-3-yn-1- yl)benzo[d]thiazol-6-yl)oxy)propyl                       4 15 methylbenzenesulfonate (35 mg) produced in Reference Example 26 and 3,4-dihydro-2H-pyrane (0.018 ml) in THF (15 ml), was added p-toluenesulfonic acid monohydrate (12 mg) at room temperature. The mixture was stirred at room temperature for 0.5 h. Then, 3,4-dihydro-2H-pyrane (0.159 ml), p-toluenesulfonic acid monohydrate (24 mg), and DMF (5 ml) were added to the mixture at room temperature. The mixture was stirred at room temperature overnight, diluted with water, and extracted with ethyl acetate. The extract was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane / ethyl acetate). The fractions containing the desired compound were concentrated under reduced pressure. The residual solid was suspended in hexane, collected by filtration, washed with hexane, and dried to obtain the title compound (21 mg) as a yellow solid. 1H NMR (300 MHz, DMSO-d6) 6 1.32-1.71 (6H, m), 2.35 (3H, s), 2.84 (3H, d, J=4.9 Hz), 3.35-3.46 (1H, m), 3.623.87 (1H, m), 4.05-4.19 (3H, m), 4.20-4.36 (2H, m), 4.654.87 (1H, m), 6.96 (1H, d, J=16.2 Hz), 7.02 (1H, dd, J=8.9, 1.6 Hz), 7.30 (1H, d, J=16.0 Hz), 7.41 (2H, d, J=7.9 Hz), 7.62 (1H, d, J=2.6 Hz), 7.67 (1H, q, J=4.4 Hz), 7.79 (2H, dd, J=8.4, 1.6 Hz), 7.86 (1H, d, J=9.0 Hz), 7.94 (1H, d, J=1.5 Hz), 8.21 (1H, d, J=1.3 Hz)

[0209] Example 10: Production Example 1 of [18F]SPAL-T-06 By the following scheme, SPAL-T-06 in which a fluorine atom was 18F (hereinafter referred to as [18F] SPAL-T-06) was produced.

[0210] [18F]epifluorohydrin was synthesized by (i) nucleophilic substitution of glycidyl tosylate with use of [18F]fluoride ions and (ii) purification by distillation. The following reaction was carried out under dim light. [18 F]epifluorohydrin, a DMF (250 pl) solution containing (E)-2-(4-(5-(methylamino)pyrazine-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-ol (2 mg) produced in Example 3, and a 1M aqueous sodium hydroxide solution (6.5 pl) were introduced into a reaction vessel. A reaction mixture was heated at 130°C for 20 minutes. After the reaction vessel was cooled, an HPLC solvent (500 pl) to be used for the subsequent HPLC was introduced into the reaction vessel. 5 A mixed solution thus obtained was purified by HPLC (HPLC: CAPCELL PAK C18 UG80 10 mm x 250 mm, acetonitrile / water=4 / 6 (containing 0.1% triethylamine), 5 ml / minute). A fraction corresponding to [18F]SPAL-T-06 was collected in a flask containing ethanol (300 pl), 25% 10 ascorbic acid (100 pl), and Tween80 (75 pl). Then, a solvent was evaporated under reduced pressure. A residue was dissolved in physiological saline (3 ml, pH 7.4) to obtain [18F]SPAL-T-06 as an injection solution.

[0211] 15             Example 11: Production Example 2 of [18F]SPAL-T-06 By the following scheme, [18F]SPAL-T-06 was produced.

[0212] 10 [18F]fluoride ions were eluted with a 50% acetonitrile solution (0.4 ml) containing K.222 (Kryptofix 222) (7.5mg) and potassium carbonate (2.77 mg). A resulting solution was introduced into a reaction vessel, and then heated under a nitrogen gas flow to dry and solidify a solvent. Subsequently, anhydrous acetonitrile (0.1 ml) was added to the reaction vessel. The solvent was azeotropically evaporated, and the inside of the reaction vessel was sufficiently dried. The following reaction was carried out under dim light. A DMSO (300 pl) solution containing (E) -3-((2-(4-(5-(methylamino)pyrazin-2-yl)but-1-en-3-yn-1-yl)benzo[d]thiazol-6-yl)oxy)-2-((tetrahydro-2H-pyran-2- yl)oxy)propyl 4-methylbenzenesulfonate (2 mg) produced in Example 9 was introduced into the reaction vessel. A reaction mixture was heated at 120°C for 15 minutes. After the reaction ves sel was cooled, TFA / water (600 pl) was added to carry out hydrolysis at 90°C for 10 minutes. After the reaction vessel was cooled, an aqueous 4N sodium acetate solution (1 ml) was added to the reaction vessel, and a mixture thus obtained was stirred. A mixed solution thus obtained was purified by HPLC (HPLC: CAPCELL PAK C18 UG80 10 mm x 250 mm, acetonitrile / water = 4 / 6 (containing 0.1% triethylamine), 5 ml / minute). A fraction corresponding to [18F]SPAL-T-06 was collected in a flask containing ethanol (300 pl), 25% ascorbic acid (100 pl), and Tween80 (75 pl). Then, a solvent was evaporated under reduced pressure. A residue was dissolved in physiological saline (3 ml, pH 7.4) to obtain [18F]SPAL-T-06 as an injection solution.

[0213] [Optical imaging of human brain] (Dissected brain tissue) Postmortem human brains were obtained in autopsies carried out with respect to a patient with dementia with Lewy bodies (DLB) and a patient with Alzheimer's disease (AD). In a cryostat (HM560, Carl Zeiss), frozen tissue from the DLB patient was sliced into sections each having a thickness of 20 pm. Brain tissue from the AD patient was fixed in 10% neutral buffered formalin, embedded in a paraffin block, and sliced into sections each having a thickness of 6 pm.

[0214] (In vitro fluorescence microscope measurement) Postfixed fresh frozen sections of amygdala tissue obtained from the brain of the DLB patient and deparaffinized sections of formalin-fixed paraffin-embedded middle frontal gyrus tissue obtained from the brain of the AD patient were used. Each brain section and a 30 pM test compound were incubated in a 50% ethanol solution at room temperature for 30 minutes. Thereafter, the section was washed with a 50% ethanol solution for 5 minutes and with ultrapure water for 3 minutes. This washing was carried out twice. After the section was mounted in a mounting medium (VECTASHIELD H-1000, Vector Laboratories), an image of a lesion-enriched area on the section was obtained with use of a fluorescence microscope (DM4000, Leica, excitation wavelength: 391 nm to 437 nm). Fluorescence images are shown in Fig. 1. In Fig. 1, each arrowhead indicates fluorescence from the compound binding to a-synuclein aggregates in the brain of the DLB patient, each arrow indicates fluorescence from the compound binding to amyloid-0 aggregate s in the brain of the AD patient, and an asterisk indicates fluorescence from the compound binding to tau aggregates in the brain of the AD patient. The fluorescence intensities of lesion-enriched areas and lesion-free areas (background) were quantified with use of analysis software (Image J). Results are shown in Fig. 2. Note that SPAL-T-05 and SPAL-T-06 were each used as the test compound. Note also that BF-227     (2-(2-[2-dimethylaminothiazol-5-yl]ethenyl)-6-(2- [fluoro]ethoxy)benzoxazole (catalog No. : NP039-0)) and PBB3 (2-((1E,3E)-4-(6-(methylamino)pyridin-3-yl)buta- 1,3-dienyl)benzo[d]thiazol-6-ol) (catalog No. : NP039-0), each available from NARD INSTITUTE, LTD., were each used as a control compound.

[0215] As shown in Figs. 1 and 2, it was found that SPAL-T-06 and SPAL-T-05 each bound to, with reactivity greater than that of PBB3, a-synuclein aggregates formed in the brain of the DLB patient. It was also found that binding of each of SPAL-T-06 and SPAL-T-05 to the a-synuclein aggregates was greater than binding of each of SPAL-T-06 and SPAL-T-05 to tau aggregates or amyloid-0 aggregates formed in the brain of the AD patient. That is, it was indicated that the compound in accordance with an embodiment of the present invention had high binding selectivity with respect to a-synuclein aggregates. Note that in vitro fluorescence microscope measurement was carried out with respect to the brain of a patient with multiple system atrophy (MSA) in a manner similar to that with respect to the brain of the DLB patient, and similar results were obtained.

[0216] Note that it was found that BF-227, which was reported as a PET probe for an a-synuclein lesion, mainly bound to the amyloid-0 aggregates in the AD patient and binding of BF-227 to the a-synuclein aggregates was weaker than that of each of SPAL-T-06 and SPAL-T-05 to the a-synuclein aggregates. That is, it was indicated that BF-227 had low binding selectivity with respect to a-synuclein aggregates.

[0217] [Optical imaging of mouse brain] (Preparation of a-synuclein fibril-inoculated mouse model) When mouse a-synuclein is expressed in and extracted from E. coli as a recombinant protein and then incubated in vitro, insoluble a-synuclein aggregates are formed. By inoculating these a-synuclein aggregates into the striatum of a mouse, the a-synuclein aggregates propagate to surrounding areas via the neural circuitry, and an a-synuclein lesion is observed in the cerebral neocortex several months later (Masuda-Suzukake et al. Acta Neuropathol Commun 2, 88, 2014; Shimozawa et al. Acta Neuropathol Commun 5, 12, 2017). By extracting the brain of this mouse, preparing a section, and then analyzing the section by fluorescent staining, it is possible to examine whether the compound in accordance with an embodiment of the present invention binds to a lesion caused by phosphorylated a-synuclein.

[0218] (Preparation of a-synuclein fibril-inoculated mouse model) First, mouse a-synuclein was expressed in and extracted from E. coli as a recombinant protein, and then incubated in vitro to form insoluble a-synuclein aggregates. The a-synuclein aggregates were then inoculated into the striatum of a mouse. The a-synuclein aggregates propagated to surrounding areas via the neural circuitry, and a-synuclein lesions were observed in the cerebral neocortex several months later. Note that the inoculation of the a-synuclein aggregates into the striatum of the mouse was carried out in the following manner. First, hair on the head of a 9-week-old C57 / BL / 6 male mouse which had been anesthetized with 1.5% (v / v) isoflurane was removed, and the scalp was disinfected with isodine, followed by application of xylocaine and incision in the scalp to expose the skull. Then, a hole was drilled in the skull at a position of 0.05 mm posterior to the bregma and 2 mm lateral to the midline, and 3 pl of an a-synuclein fibril solution (mouse a-synuclein fibril (4 mg / ml) in saline) was injected into a position 2 pm ventral to the brain surface with use of a glass pipette. The scalp was then returned and sutured.

[0219] (In vitro fluorescence microscope measurement) The brain of this a-synuclein fibril-inoculated mouse was extracted, and then sections were prepared. The sections were analyzed by fluorescent staining. Specifically, each brain section of the a-synuclein fibril-inoculated mouse and a 30 pM compound were incubated in a 20% ethanol solution at room temperature for 30 minutes. Thereafter, the section was washed with a 20% ethanol solution for 5 minutes and with ultrapure water for 3 minutes. This washing was carried out twice. After the section was mounted in a mounting medium (VECTASHIELD H-1000), an image of an a-synuclein aggregate-enriched area on the section was obtained with use of a fluorescence microscope (DM4000 (excitation wavelength: 391 nm to 437 nm)). The same section was washed with a phosphate buffer solution, and then treated in an autoclave for antigen retrieval. After the section was subjected to immunohistochemical staining with use of an antiphosphorylated a-synuclein monoclonal antibody (pS129, abcam, ab59264) (1:1000) and then mounted in a mounting medium (VECTASHIELD H-1000), an image of the same area as above was obtained with use of a fluorescence microscope (DM4000 (excitation wavelength: 460 nm to 500 nm)). Results are shown in Fig. 3. (a) of Fig. 3 shows results obtained in relation to SPAL-T-05. (b) of Fig. 3 shows results obtained in relation to SPAL-T-06. In each of (a) and (b) of Fig. 3, a right image shows a section subjected to staining with use of the anti phosphorylated a-synuclein antibody, and a left image shows the section subjected to fluorescent staining by a corresponding one of SPAL-T-05 and SPAL-T-06. In Fig. 3, each arrowhead indicates a lesion, caused by phosphorylated a-synuclein, in the brain of the a-synuclein fibril-inoculated mouse and fluorescence from the compound binding to the phosphorylated a-synuclein.

[0220] From the results shown in Fig. 3, it was indicated that SPAL-T-05 and SPAL-T-06 bound to a lesion caused by phosphorylated a-synuclein.

[0221] [In vivo two-photon laser scanning fluorescence microscopy] A model mouse was anesthetized with 1.5% (v / v) isoflurane 6 or more weeks after inoculation of an a-synuclein fibril solution. Then, a cranial window was placed on the model mouse in accordance with the Seylaz-Tomita method (Tomita et al. J Cereb Blood Flow Metab 25, 858- 67, 2005). Two or more weeks after the placement of the cranial window, the mouse was anesthetized with 1.5% (v / v) isoflurane, and then 50 pl of a DMSO solution containing 0.1% BF-227, PBB3, SPAL-T-05, or SPAL-T-06 was intraperitoneally administered to the mouse. Thirty minutes after the administration, the mouse was fixed under a two-photon laser fluorescence microscope, 100 pl of physiological saline containing 5 mM Sulforhodamine 101 was intraperitoneally administered to the mouse, and then intravital two-photon fluorescence imaging was carried out at an excitation wavelength of 900 nm. Detection wavelengths for BF-227, PBB3, SPAL-T-05, and SPAL-T-06 were set at 500 nm to 550 nm, and a detection wavelength for Sulforhodamine 101 was set at 573 nm to 648 nm. Results are shown in Fig. 4. In Fig. 4, each arrowhead indicates a blood vessel, and each arrow indicates fluorescence from the compound binding to an a -synuclein lesion.

[0222] From the results shown in Fig. 4, it was observed by the intravital two-photon laser fluorescence microscope that when each of SPAL-T-05 and SPAL-T-06 was intraperitoneally administered, the compound was delivered into the brain and further into neurons of the living body and bound to a-synuclein lesions. Therefore, it can be said that even in a case where the density or the total number of lesions is low or small and therefore it is difficult to detect the lesions by PET, it is possible to detect the lesions by biofluorescence imaging with use of the compound in accordance with an embodiment of the present invention. In contrast, no a-synuclein lesion was detected even in a case where BF-227 and PBB3 were each intraperitoneally administered and then observation was carried out.

[0223] [In vivo positron emission tomography (PET) imaging of mouse brain] PET scanning was carried out with use of a micro PET Focus 220 animal scanner (Siemens Medical Solutions), which provided 95 slices each having a thickness of 0.851 mm (center thickness), a 19.0-cm axial field of view (FOV) and a 7.6-cm cross-sectional FOV. Before the scanning, an a-synuclein fibril-inoculated mouse and a physiological saline-injected mouse (control) were each anesthetized with 1.5% (v / v) isoflurane. Emission scanning was carried out in 3D list mode with an energy window of 350 keV to 750 keV for 90 minutes, after intravenous injection of [18F]SPAL-T-06 (compound in which SPAL-T-06 was labeled with a positron-emitting radionuclide) (30.1±0.13 MBq). The injection of the radioactive compound and the scanning were carried out under dim light so as to avoid photoisomerization of the compound. The entire list mode data was sorted into 3D sinograms, and then the 3D sinograms were converted into 2D sinograms by Fourier-rebining (frame: 10x1, 6x5, and 5x10 minutes). After the injection of the radioactive compound, summation images during time periods from 0 to 30 minutes, from 30 to 60 minutes, and from 60 to 90 minutes were obtained by maximum a posteriori reconstruction. Moreover, dynamic images were reconstructed by filtered back projection with use of a 0.5-mm Hanning filter. A volume of interest (VOI) was defined for each of the striata, the cerebral cortices, and the cerebella with use of PMOD image analysis software (PMOD Technologies), with reference to an MRI template. Results are shown in Figs. 5 to 7.

[0224] The left images in Fig. 5 show results obtained from the a-synuclein fibril-inoculated mouse 30 to 60 minutes after the intravenous injection of [18F]SPAL-T-06. The right images in Fig. 5 show results obtained from the physiological saline-injected mouse. The upper images show coronal sections of the brains which include the striata, and the lower images show coronal sections of the brains which include the cerebella. These images are superimposed on standard brain MRI images. Fig. 6 shows time-radioactivity curves obtained from the striata, the cerebral cortices, and the cerebella after the intravenous injection of [18F]SPAL-T-06. (a) to (d) of Fig. 7 show temporal changes of standardized uptake value ratios (SUVRs) of the striata to the cerebella (reference) and SUVRs of the cerebral cortices to the cerebella (reference) after the intravenous injection of [18F]SPAL-T-06, and comparisons of the average SUVRs in the a-synuclein fibril-inoculated mouse with those in the physiological saline-injected mouse during the time period from 30 to 60 minutes (n=2, mean±SEMs). (a) of Fig. 7 shows temporal changes of the SUVRs of the striata to the cerebella (reference areas) after the intravenous injection of [18F] SPAL-T-06. (b) of Fig. 7 shows the average SUVRs of the striata (reference areas: cerebella) during the time period from 30 to 60 minutes. (c) of Fig. 7 shows temporal changes of the SUVRs of the cerebral cortices to the cerebella (reference areas) after the intravenous injection of [18F]SPAL-T-06. (d) of Fig. 7 shows the average SUVRs of the cerebral cortices (reference areas: cerebella) during the time period from 30 to 60 minutes.

[0225] As a result of labeling SPAL-T-06 with the positronemitting radionuclide, intravenously injecting SPAL-T-06 into the a-synuclein fibril-inoculated model mouse and the physiological saline-injected mouse (control), and then carrying out PET scanning, it became clear that SPAL-T-06 had an adequate brain-entering property or an adequate clearance rate from the brains and exhibited a favorable characteristic as a probe for imaging of a-synuclein aggregates by PET, as shown in Figs. 5 to 7. Note that, in the a-synuclein fibril-inoculated model mouse, clear accumulation of [18F]SPAL-T-06 in the striatum and the cerebral cortex, each of which was rich in a-synuclein lesions, was seen. Thus, it was found that PET scanning with use of [18F]SPAL-T-06 enabled imaging of a-synuclein aggregates.

[0226] [Ex vivo imaging of mouse brain] A physiological saline-injected mouse was anesthetized with 1.5% (v / v) isoflurane. Then, [18F]SPAL-T-06 (28.9 MBq) was intravenously injected into the physiological saline-injected mouse. Forty minutes after the administration of [18F]SPAL-T-06, the brain was collected and frozen. In a cryostat (HM560), frozen coronal sections each having a thickness of 20 pm and respectively including positions at 0.50 mm, -0.46 mm, -1.94 mm, -3.16 mm, and -6.64 mm from the bregma were prepared. Each section was air-dried, and then placed in contact with an imaging plate for 15 minutes in a cassette. Thereafter, autoradiographs were obtained with use of BAS-5000 (Fuji Film). Results are shown in Fig. 8.

[0227] It was found, from the results shown in Fig. 8, that even when [18F]SPAL-T-06 was intravenously injected into the physiological saline-injected mouse, nonspecific accumulation of the compound delivered into the brain was not seen in the white matter area.

[0228] [Positron emission tomography (PET) imaging of marmoset brain] (Preparation of    a-synuclein    fibril-inoculated marmoset model) First, marmoset a-synuclein was expressed in and extracted from E. coli as a recombinant protein, and then incubated in vitro to form insoluble a-synuclein aggregates. The a-synuclein aggregates were then inoculated into the caudate nucleus and the putamen of the marmoset. The a-synuclein aggregates propagated to surrounding areas via the neural circuitry, and a-synuclein lesions were observed in the substantia nigra several months later. The inoculation of the a-synuclein aggregates into the caudate nucleus and the putamen of the marmoset was carried out in the following manner. First, an endotracheal tube was inserted into the marmoset immobilized with ketamine (5 mg / kg to 10 mg / kg) and xylazine (0.2 mg / kg to 0.5 mg / kg), and then the marmoset was anesthetized with 1% to 3% (v / v) isoflurane. Then, hair on the head of the marmoset was removed, and the scalp was disinfected with isodine, followed by application of xylocaine and incision in the scalp to expose the skull. A hole (a diameter of approximately 3 mm) was drilled in the skull at a position of 9.75 mm from the interaural line, and 50 pl of an a-synuclein fibril solution (marmoset a -synuclein fibril (4 mg / ml) in saline) was injected into each of the caudate nucleus and the putamen in the right hemisphere with use of a Hamilton's syringe. Furthermore, 50pl of physiological saline was injected into each of the caudate nucleus and the putamen in the left hemisphere in a similar manner. Thereafter, the scalp was returned and sutured.

[0229] [In vivo positron emission tomography (PET) imaging of marmoset brain] PET scanning was carried out with use of a micro PET Focus 220 animal scanner (Siemens Medical Solutions), which provided 95 slices each having a thickness of 0.851 mm (center thickness), a 19.0-cm axial field of view (FOV) and a 7.6-cm cross-sectional FOV. Before the scanning, the a-synuclein fibril-inoculated marmoset was anesthetized with 1% to 3% (v / v) isoflurane. Transmission scanning was carried out with use of a PET calibration source Ge-68 for 20 minutes. Emission scanning was carried out in 3D list mode with an energy window of 350 keV to 750 keV for 90 minutes, after intravenous injection of [18F]SPAL-T-06 (compound in which SPAL-T-06 was labeled with a positron emitting radionuclide) (73.0 MBq). The injection of the radioactive compound and the scanning were carried out under dim light so as to avoid photoisomerization of the compound. The entire list mode data was sorted into 3D sinograms, and then converted into 2D sinograms by Fourier-rebining (frame: 10x1, 6x5, and 5x10 minutes). After the injection of the radioactive compound, summation images during time periods from 0 to 30 minutes, from 30 to 60 minutes, and from 60 to 90 minutes were obtained by maximum a posteriori reconstruction. Moreover, dynamic images were reconstructed by filtered back projection with use of a 0.5-mm Hanning filter. A result is shown in Fig. 9. (a) of Fig. 9 shows an image of a coronal section of the brain of the a-synuclein fibril-inoculated marmoset which includes the caudate nucleus, 20 minutes to 60 minutes after the intravenous injection of [18F]SPAL-T-06. The image is superimposed on a standard brain MRI image.

[0230] (In vitro fluorescence microscope measurement) The brain of the a-synuclein fibril-inoculated marmoset was extracted, and then a section was prepared. The section was analyzed by immunohistochemical staining. Specifically, the brain section of the a-synuclein fibril-inoculated marmoset was washed with a phosphate buffer solution, and then treated in an autoclave for antigen retrieval. After the section was subjected to immunohistochemical staining with use of an antiphosphorylated a-synuclein monoclonal antibody (pS129, abcam, ab59264) (1:1000) and then mounted in a mounting medium (VECTASHIELD H-1000), images were obtained with use of fluorescence microscopes (BZ-X710, KEYENCE (excitation wavelength: 450 nm to 490 nm) and DM4000 (excitation wavelength: 460 nm to 500 nm)). A result is shown in Fig. 9. (b) of Fig. 9 shows an image of antibody staining, using anti-phosphorylated a-synuclein antibody, of the coronal section of the brain including the caudate nucleus obtained from of the a-synuclein fibril-inoculated marmoset. In (b) of Fig. 9, 2 shows an enlarged image of the caudate nucleus in the right hemisphere to which the a-synuclein fibril was inoculated and which was stained with anti-phosphorylated a-synuclein antibody, and 1 shows an enlarged image of the caudate nucleus in the left hemisphere to which the physiological saline was injected and which was stained with anti-phosphorylated a-synuclein antibody.

[0231] By carrying out PET scanning of the a-synuclein fibril-inoculated model marmoset into which SPAL-T-06 labeled with a positron-emitting   radionuclide was intravenously injected, clear accumulation of [18F] SPAL-T-06 in the caudate nucleus, which was rich in a-synuclein lesions, was observed. Thus, it was found that PET scanning with use of [18F]SPAL-T-06 enabled imaging of a-synuclein aggregates.

[0232] [In vitro biding test of human brain] Fresh frozen tissue from the amygdala in the brain of a DLB patient and fresh frozen tissue from the frontal cortex in the brain of an AD patient were used. To each fresh frozen brain tissue, zirconia beads (ZB-20, TOMY) and a buffer solution which was 10 times the wet weight of the tissue were added. A mixture thus obtained was smashed with use of Micro Smash (MS-100R, TOMY) and then stored at -80°C. A homogenate of the brain of the DLB patient or a homogenate of the brain of the AD patient, [18F]SPAL-T-06 (final concentration: 5 nM), and nonlabeled SPAL-T-06 (final concentration: 0.01 nM to 1 pM) were mixed into a Tris-HCl buffer solution (containing 20% ethanol). Incubation was carried out at room temperature for 30 minutes, and then B / F separation (B: bound ligand, F: free ligand) was carried out by suction filtration and washing. Thereafter, radioactivity captured on a glass filter was measured with use of a gamma counter (2480WIZARD2, ParkinElmer). With regard to the concentration of each non-labeled SPAL-T-06, a test was carried out in triplicate. Results were analyzed with use of Prism 6J (GraphPad), displacement curves of the tested compounds were obtained, and then IC50 of each was calculated. Results are shown in Fig. 10.

[0233] As a result of binding tests with SPAL-T-06 labeled with a positron-emitting radionuclide and the homogenate of the brain of the DLB patient and the homogenate of the brain of the AD patient, it was found that [18F]SPAL-T-06 bound, with high affinity, to the homogenate of the brain of the DLB patient which was rich in a-synuclein lesions (IC50=1.58 nM). It was found that the binding affinity of [18F]SPAL-T-06 with respect to the homogenate of the brain of the AD patient was lower (IC50=10.86 nM) than that of [18F]SPAL-T-06 with respect to the homogenate of the brain of the DLB patient, that [18F]SPAL-T-06 exhibited favorable binding affinity as a probe for imaging a-synuclein aggregates in PET imaging, and that binding of [18F]SPAL-T-06 to a-synuclein aggregates was stronger than to tau aggregates or amyloid 0 aggregates and thus had high binding selectivity with respect to a-synuclein aggregates.

[0234] [In vitro autoradiography of human brain] (Dissected brain tissue) Postmortem human brains were obtained in autopsies carried out with respect to a DLB patient, a multiple system atrophy (MSA) patient, and a healthy subject. In a cryostat (HM560, Carl Zeiss), frozen tissue from the DLB patient and frozen tissue from the healthy subject were sliced into sections each having a thickness of 20 pm. Brain tissue from the MSA patient was fixed in 10% neutral buffered formalin, embedded in a paraffin block, and sliced into sections each having a thickness of 6 pm.

[0235] (Autoradiography test) Postfixed fresh frozen sections of amygdala tissue from the brain of the DLB patient and the frontal cortex tissue from the brain of the healthy subject and deparaffinized sections of formalin-fixed paraffin-embedded cerebellum tissue from the brain of the MSA patient were used. Each brain tissue section and [18F]SPAL-T-06 (final concentration: 10 nM) were incubated in 50 mM Tris-HCl containing 20% ethanol at room temperature for 1 hour. In order to detect specific binding, the brain tissue section was also incubated in 50 mM Tris-HCl (containing 20% ethanol) containing [18F]SPAL-T-06 (final concentration: 10 nM) and non-labeled SPAL-T-06 (final concentration: 10 pM). Subsequently, the section was washed with 50 mM Tris-HCl (containing 20% EtOH) at 4°C for 2 minutes. This washing was carried out twice. Thereafter, the section was rinsed with MilliQ. The section was air-dried, and then placed in contact with an imaging plate for 5 minutes in a cassette. Thereafter, an autoradiograph was obtained with use of BAS-5000 (Fuji Film). Results are shown in Fig. 11. In Fig. 11, each arrowhead indicates an area in each of the brains of the DLB patient and the MSA patient which includes a lesion caused by phosphorylated a-synuclein.

[0236] (In vitro fluorescence microscope measurement) The section that had been subjected to the autoradiography was analyzed by fluorescent staining. Specifically, the section and 30 pM SPAL-T-06 were incubated in a 50% ethanol solution at room temperature for 30 minutes. Thereafter, the section was washed with a 50% ethanol solution for 5 minutes and with ultrapure water for 3 minutes. This washing was carried out twice. After the section was mounted in a mounting medium (VECTASHIELD H-1000), an image of an a-synuclein aggregate-enriched area on the section was obtained with use of a fluorescence microscope (DM4000 (excitation wavelength: 391 nm to 437 nm)). An adjacent brain section was also washed with a phosphate buffer solution, and then treated in an autoclave for antigen retrieval. After the section was subjected to immunohistochemical staining with an anti-phosphorylated a-synuclein monoclonal antibody (pS129, abcam, ab59264) (1:1000) and then mounted in a mounting medium (VECTASHIELD H-1000), images were obtained with use of fluorescence microscopes (BZ-X710, KEYENCE (excitation wavelength: 450 nm to 490 nm) and DM4000 (excitation wavelength: 460 nm to 500 nm)). Results are shown in Fig. 12. (a) (indicated by "1") of Fig. 12 shows the brain of the DLB patient which has been subjected to staining with use of the antiphosphorylated a-synuclein antibody and fluorescent staining by SPAL-T-06. (b) (indicated by "2") of Fig. 12 shows the brain of the MSA patient which has been subjected to staining with use of the anti-phosphorylated a-synuclein antibody and fluorescent staining by SPAL-T-06.

[0237] As a result of autoradiography of a section of the amygdala in the brain of the DLB patient, a section of the cerebellum in the brain of the MSA patient, and a section of the frontal cortex in the brain of the healthy subject using SPAL-T-06 labeled with a positron-emitting radionuclide, it was found that [18F]SPAL-T-06 bound to areas in the brains of the DLB patient and the MSA patient which were rich in lesions caused by phosphorylated a-synuclein. As a result of fluorescent staining and immunohistochemical staining of the sections that had been subjected to the autoradiography, it was found that SPAL-T-06 bound to a-synuclein lesions included in these brain sections. In the section of the frontal cortex in the brain of the healthy subject, non-specific binding of [18F]SPAL-T-06 was hardly observed in both of the gray matter and the white matter. 5 Industrial Applicability

[0238] According to the present invention, it is possible to provide an a-synuclein aggregate binding agent having 10 high binding selectivity with respect to a-synuclein aggregates. Furthermore, it is possible to provide a method for carrying out imaging with use of this a-synuclein aggregate binding agent. Moreover, it is possible to provide a novel compound which can be used for the a- 15 synuclein aggregate binding agent or the other applications.

Claims

Claim 1A compound represented by the following formula (I)or (II), a pharmaceutically acceptable salt thereof, or a5 solvate thereof.Claim 2The compound, the pharmaceutically acceptable salt10 thereof, or the solvate thereof as set forth in claim 1, wherein one or more atoms in the compound represented by the formula (I) or (II) are radioisotopes thereof.Claim 315             An a-synuclein aggregate binding agent comprisinga compound, a pharmaceutically acceptable salt, or asolvate thereof recited in claim 1.Claim 4An a-synuclein aggregate binding agent comprising a compound, a pharmaceutically acceptable salt, or a solvate thereof recited in claim 2.Claim 5A composition for optical imaging of a-synuclein aggregates, said composition comprising an a-synuclein aggregate binding agent recited in claim 3.Claim 6A composition for radiological imaging of a-synuclein aggregates, said composition comprising an a-synuclein aggregate binding agent recited in claim 4.Claim 7A method for carrying out optical imaging of a-synuclein aggregates in brain, said method comprising astep of detecting light which has a second wavelength and which is emitted from the brain of a living subject, after externally irradiating the brain with light which has a first wavelength, wherein an a-synuclein aggregate binding5 agent recited in claim 3 has been administered to the living subject, and the first wavelength and the second wavelength are different from each other.Claim 810             A method for carrying out radiological imaging of a-synuclein aggregates in brain, said method comprising a step of detecting radioactivity which is emitted from the brain of a living subject to which an a-synuclein aggregate binding agent recited in claim 4 has been administered.15Claim 9An intermediate for synthesizing the compound recited in claim 1 or 2, the intermediate being representedby the following formula (III):wherein:one of X and Y is a nitrogen atom (N), and the other is an unsubstituted carbon atom (CH);5             R1 is a hydroxy group or a group represented by thefollowing formula (i):OTHPwherein Ts represents a p-toluenesulfonyl group,THP represents a tetrahydro-2H-pyran-2-yl group,10 and* represents a position to which a benzothiazole ring binds; andR2 is a hydrogen atom or a tert-butoxycarbonyl (Boc) group.15

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