Florbetaben (18F)

PHOTO CREDIT-KEGG

902143-01-5 cas no

(18F-AV-1/ZK; BAY-94-9172; 18F-BAY-94-9172; ZK-6013443)

Mr Ajay Piramal, Chairman, Piramal Healthcare

Imaging with amyloid-β PET can potentially aid the early and accurate diagnosis of Alzheimer’s disease. Florbetaben (¹⁸F) is a promising ¹⁸F-labelled amyloid-β-targeted PET tracer in clinical development. We aimed to assess the sensitivity and specificity of florbetaben (¹⁸F) PET in discriminating between patients with probable Alzheimer’s disease and elderly healthy controls.

METHODS:

We did a multicentre, open-label, non-randomised phase 2 study in 18 centres in Australia, Germany, Switzerland, and the USA. Imaging with florbetaben (¹⁸F) PET was done on patients with probable Alzheimer’s disease (age 55 years or older, mini-mental state examination [MMSE] score=18-26, clinical dementia rating [CDR]=0·5-2·0) and age-matched healthy controls (MMSE ≥ 28, CDR=0). Our primary objective was to establish the diagnostic efficacy of the scans in differentiating between patients with probable disease and age-matched healthy controls on the basis of neocortical tracer uptake pattern 90-110 min post-injection. PET images were assessed visually by three readers masked to the clinical diagnosis and all other clinical findings, and quantitatively by use of pre-established brain volumes of interest to obtain standard uptake value ratios (SUVRs), taking the cerebellar cortex as the reference region. This study is registered with ClinicalTrials.gov, number NCT00750282.

FINDINGS:

81 participants with probable Alzheimer’s disease and 69 healthy controls were assessed. Independent visual assessment of the PET scans showed a sensitivity of 80% (95% CI 71-89) and a specificity of 91% (84-98) for discriminating participants with Alzheimer’s disease from healthy controls. The SUVRs in all neocortical grey-matter regions in participants with Alzheimer’s disease were significantly higher (p < 0·0001) compared with the healthy controls, with the posterior cingulate being the best discriminator. Linear discriminant analysis of regional SUVRs yielded a sensitivity of 85% and a specificity of 91%. Regional SUVRs also correlated well with scores of cognitive impairment such as the MMSE and the word-list memory and word-list recall scores (r -0·27 to -0·33, p ≤ 0·021). APOE ɛ4 was more common in participants with positive PET images compared with those with negative scans (65%vs 22% [p=0·027

MAR 21 2013

Piramal Imaging SA, a division of Piramal Enterprises, today announced that the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have accepted its applications for review of the investigational PET amyloid imaging agent [18F] florbetaben. A New Drug Application (NDA) was submitted to the U.S. Food and Drug Administration (FDA) and a Marketing Authorization Application to the EMA for [18F] florbetabenuse in the visual detection of beta-amyloid in the brains of adultswith cognitive impairment who are being evaluated for Alzheimer’s disease and other causes of cognitive decline.[18F] florbetaben binds to beta-amyloid plaques in the human brain, a hallmark characteristic in Alzheimer’s disease.

Today, Alzheimer’s disease is usually diagnosed after a person with a cognitive impairment undergoes an extensive clinical examination which typically includes family and medical history, physical and neurological examinations, laboratory tests, and imaging procedures such as computed tomography (CT) and magnetic resonance imaging (MRI) scans. Still, a definitive diagnosis of Alzheimer’s disease can only be made after death where an autopsy can reveal the presence of beta-amyloid plaques and neurofibrillary tangles in the brain. However, post-mortem studies looking for accumulations of beta-amyloid in the brain have shown that 10 to 30 percent of diagnoses based on clinical examinations are incorrect. [18F] florbetaben is being studied to determine its potential ability to detect beta-amyloid plaquesin living subjects with cognitive impairment.

FLORBETABEN F18

Diagnostic radiopharmaceutical

1. Benzenamine, 4-[(1E)-2-[4-[2-[2-[2-(fluoro-18F)ethoxy]ethoxy]ethoxy]phenyl]
ethenyl]-N-methyl-

2. 4-{(1E)-2-(4-{2-[2-(2-[18F]fluoroethoxy)ethoxy]ethoxy}phenyl)eth- 1-en-1-yl}-N-methylaniline

C21H26[18F]NO3
358.5
Bayer Healthcare

UNII-TLA7312TOI
CAS REGISTRY NUMBER  902143-01-5
https://www.ama-assn.org/resources/doc/usan/florbetaben-f18.pdf

4-[(E)-2-(4-{2-[2-(2-fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline has been labeled with [F-18]fluoride and is claimed by patent application WO2006066104 and members of the corresponding patent family.

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

The usefulness of this radiotracer for the detection of Αβ plaques have been reported in the literature (W. Zhang et al., Nuclear Medicine and Biology 32 (2005) 799-809; C. Rowe et al., Lancet Neurology 7 (2008) 1 -7).

The synthesis of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)- vinyl]-N-methylaniline has been described before:

a) W. Zhang et al., Nuclear Medicine and Biology 32 (2005) 799-809.

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

4 mg precursor 2a (2-[2-(2-{4-[(E)-2-{4-[(tert-butoxycarbonyl)(methyl)amino]- phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl methanesulfonate) in 0.2 mL

DMSO were reacted with [F-18]fluoride/kryptofix/potassium carbonate complex. The intermediate was deprotected with HCI and neutralized with

NaOH. The mixture was extracted with ethyl acetate. The solvent was dried and evaporated, the residue was dissolved in acetonitrile and purified by semi-preparative HPLC. 20% (decay corrected), 1 1 % (not corrected for decay) 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N- methylaniline were obtained in 90 min.

WO2006066104

4 mg precursor 2-[2-(2-{4-[(E)-2-{4-[(tert-butoxycarbonyl)(methyl)amino]- phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl methanesulfonate in 0.2 mL DMSO were reacted with [F-18]fluoride/kryptofix/potassium carbonate complex. The intermediates was deprotected with HCI and neutralized with NaOH. The mixture was extracted with ethyl acetate. The solvent was dried and evaporated, the residue was dissolved in acetonitrile and purified by semi- preparative HPLC. 30% (decay corrected), 17% (not corrected for decay) 4- [(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N- methylaniline were obtained in 90 min. to yield N-Boc protected 4-[(E)-2-(4-{2-[2-(2-[F- 18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline. The unreacted perfluorinated precursor was removed using a fluorous phase cartridge.

Deprotection, final purification and formulation to obtain a product, suitable for injection into human is not disclosed. Furthermore, the usefulness (e.g. regarding unwanted F-19/F-18 exchange) of this approach at a higher radioactivity level is not demonstrated. Finally, this method would demand a two-pot setup (first reaction vessel: fluorination, followed by solid-phase- extraction, and deprotection in the second reaction vessel).

However, the focus of the present invention are compounds and methods for an improved “one-pot process” for the manufacturing of 4-[(E)-2-(4-{2-[2-(2- [F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline.

Very recently, further methods have been described:

d) US201001 13763

The mesylate precursor 2a was reacted with [F-18]fluoride species in a solvent mixture consisting of 100 μΙ_ acetonitrile and 500 μΙ_ tertiary alcohol. After fluorination for 10 min at 100-150 °C, the solvent was evaporated. After deprotection (1 N HCI, 5 min, 100-120 °C), the crude product was purified by HPLC (C18 silica, acetonitrile / 0.1 M ammonium formate).

e) H. Wang et al., Nuclear Medicine and Biology 38 (201 1 ) 121 -127

5 mg precursor 2a (2-[2-(2-{4-[(E)-2-{4-[(tert-butoxycarbonyl)(methyl)amino]- phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl methanesulfonate) in 0.5 ml_

DMSO were reacted with [F-18]fluoride/kryptofix/potassium carbonate complex. The intermediate was deprotected with HCI and neutralized with NaOH. The crude product was diluted with acetonitrile / 0.1 M ammonium dformate (6/4) and purified by semi-preparative HPLC. The product fraction was collected, diluted with water, passed through a C18 cartridge and eluted with ethanol, yielding 17% (not corrected for decay) 4-[(E)-2-(4-{2-[2-(2-[F- 18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline within 50 min. In the paper, the conversion of an unprotected mesylate precursor (is described:

5 mg unprotected mesylate precursor (2-{2-[2-(4-{(E)-2-[4- (methylamino)phenyl]vinyl}phenoxy)ethoxy]-ethoxy}ethyl 4- methanesulfonate) in 0.5 ml_ DMSO were reacted with [F- 18]fluoride/kryptofix/potassium carbonate complex. The crude product was diluted with acetonitrile / 0.1 M ammonium formate (6/4) and purified by semi- preparative HPLC. The product fraction was collected, diluted with water, passed through a C18 cartridge and eluted with ethanol, yielding 23% (not corrected for decay) 4-[(E)-2-(4-{2-[2-(2-[F-

18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline within 30 min. Beside the purification by HPLC, a process based on solid-phase-extraction was investigated, but the purity was inferior to that with HPLC purification. So far, one-pot radiolabelings have been performed using a mesylate precursor. It is know, that for F-18 labeling of stilbenes, mesylates have advantages over corresponding tosylates by providing more clean reactions with less amount of by-products (W. Zhang et al. Journal of Medicinal Chemistry 48 (2005) 5980- 5988), whereas the purification starting from the tosylate precursor was tedious and time consuming resulting in a low yield.

In contrast to this teaching of the prior art, we found advantages of tosylate and further arylsulfonate precursors for 4-[(E)-2-(4-{2-[2-(2-[F- 18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline compared to the corresponding mesylate. Less non-radioactive by-products that eluted close to the retention time of 4-[(E)-2-(4-{2-[2-(2-[F-

18]fluoroethoxy)ethoxy]ethoxy}phenyl)vinyl]-N-methylaniline were found in the crude products if arylsulfonate precursors were used (Example 2 – Example 6) compared to the crude mixture that was obtained after conversion of the mesylate precursor (Example 1 ).

The favorable by-product profile after radiolabeling of tosylate precursor 2b (Figure 10) compared to the radiolabeling of mesylate precursor 2a (Figure 7) supported an improved cartridge based purification (Example 8, Example 9).

…………………

WO2011151281A1

The term “F-18” means fluorine isotope ¹⁸F. The term”F-19″ means fluorine isotope ¹⁹F. EXAMPLES

Example 1 Radiolabeling of mesylate precursor 2a

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

Radiolabeling was performed on a remote controlled synthesis module (Tracerlab FXN). Precursor 2a (2 mg) in 0.5 mL DMSO + 0.5 mL acetonitrile was treated with dried potassium carbonate/kryptofix/[F-18]fluoride complex for 6 min at 100 °C. 1 M HCI (1 mL) + 10 mg ascorbic acid was added and the mixture was heated for 4 min at 100 °C. 2M NaOH (0.5 mL), water (6 mL) and ethanol (1 mL) were added and the crude mixture was trapped on a C18 cartridge. The crude product mixture was eluted with acetonitrile and diluted with 0.1 M ammonium formiat buffer (1 mL) + 5 mg ascorbic acid. A sample of the crude product was taken and analyzed by analytical HPLC (Figure 1 ). After purification by semi- preparative HPLC, the product was diluted with water + 5 mg ascorbic acid, trapped on a C18 cartridge and eluted with 1 mL ethanol.

Yield of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)-vinyl]-N- methylaniline: 21 % (corrected for decay).

Example 2 Synthesis and radiolabeling of tosylate precursor 2b

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

4-Dimethylaminopyridine (26.7 mg) and triethylamine (225 μΙ_) were added to a solution of 1 .0 g terf-butyl {4-[(E)-2-(4-{2-[2-(2- hydroxyethoxy)ethoxy]ethoxy}phenyl)vinyl]phenyl}methylcarbamate (4) in dichloromethane (12 mL) at 0 °C. A solution of p- toluenesulfonyl chloride (417 mg) in dichloromethane (13.5 mL) was added at 0 °C. The resulting mixture was stirred at room temperature over night. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography (silica, 0- 80% ethyl acetate in hexane). 850 mg 2b were obtained as colorless solid.

1 H NMR (300 MHz, CDCI3) δ ppm 1 .46 (s, 9 H), 2.43 (s, 3 H), 3.27 (s, 3 H), 3.59-3.73 (m, 6 H), 3.80- 3.86 (m, 2 H), 4.05-4.19 (m, 2 H), 6.88-7.05 (m, 4 H), 7.21 (d, J = 8.3 Hz, 2 H), 7.32 (d, J = 8.3 Hz, 2 H), 7.39-7-47 (m, 4 H), 7.80 (d, J = 8.3 Hz, 2 H). MS (ESIpos): m/z = 612 (M+H)⁺

Radiolabeling was performed on a remote controlled synthesis module (Tracerlab FX_N). Precursor 2b (2 mg) in 0.5 mL DMSO + 0.5 mL acetonitrile was treated with dried potassium carbonate/kryptofix/[F-18]fluoride complex for 6 min at 100 °C. 1 M HCI (1 mL) + 10 mg ascorbic acid was added and the mixture was heated for 4 min at 100 °C. 2M NaOH (0.5 mL), water (6 mL) and ethanol (1 mL) were added and the crude mixture was trapped on a C18 cartridge. The crude product mixture was eluted with acetonitrile and diluted with 0.1 M ammonium formiat buffer (1 mL) + 5 mg ascorbic acid. A sample of the crude product was taken and analyzed by analytical HPLC (Figure 2). After purification by semi- preparative HPLC, the product was diluted with water + 5 mg ascorbic acid, trapped on a C18 cartridge and eluted with 1 mL ethanol.

Yield of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)-vinyl]-N- methylaniline: 25% (corrected for decay).

Example 3 Synthesis and radiolabeling of 2c (2-[2-(2-{4-[(E)-2-{4-[(tert- butoxycarbonyl)(methyl)amino]phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl

4-bromobenzenesulfonate)

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline To a stirred solution of 100 mg (0,219 mmol) tert-butyl-{4-[(E)-2-(4-{2-[2-(2- hydroxyethoxy)ethoxy]ethoxy}phenyl)vinyl]phenyl}methylcarbamate

(WO2006/066104) in 2 mL THF was added a solution of 140 mg (0.548 mmol) 4-brombenzene sulfonylchlorid in 3 mL THF drop by drop. The reaction mixture was cooled to 0°C. 156.8 mg (1 .1 mmol) potassium trimethylsilanolat was added. The milky suspension was stirred at 0°C for 2 hours and at 80°C for another 2 hours. The reaction mixture was poured onto ice-cooled water. The aqueous solution was extracted with dichloromethane several times. The combined organic phases were dried with sodium sulphate and concentrated in vacuum. The crude product was purified using silica gel with ethyl acetate/hexane-gradient as mobile phase. The desired product 2c was obtained with 77 mg (0.1 14 mmol, 52.0 % yield).

¹ H NMR (300 MHz, CDCI₃) δ ppm 1 .39 (s, 10 H) 3.20 (s, 3 H) 3.50 – 3.57 (m, 2 H) 3.57 – 3.61 (m, 2 H) 3.61 – 3.66 (m, 2 H) 3.72 – 3.80 (m, 2 H) 4.02 – 4.10 (m, 2 H) 4.10 – 4.17 (m, 2 H) 6.79 – 6.85 (m, 2 H) 6.91 (d, J=8.10 Hz, 2 H) 7.10 – 7.17 (m, 2 H) 7.32 – 7.41 (m, 5 H) 7.57 – 7.65 (m, 2 H) 7.67 – 7.74 (m, 2 H)

MS (ESIpos): m/z = 676/678 (M+H)⁺

Radiolabeling was performed on a remote controlled synthesis module (Tracerlab FXN). Precursor 2c (2 mg) in 0.5 mL DMSO + 0.5 mL acetonitrile was treated with dried potassium carbonate/kryptofix/[F-18]fluoride complex for 6 min at 100 °C. 1 M HCI (1 mL) + 10 mg ascorbic acid was added and the mixture was heated for 4 min at 100 °C. 2M NaOH (0.5 mL), water (6 mL) and ethanol (1 mL) were added and the crude mixture was trapped on a C18 cartridge. The crude product mixture was eluted with acetonitrile and diluted with 0.1 M ammonium formiat buffer (1 mL) + 5 mg ascorbic acid. A sample of the crude product was taken and analyzed by analytical HPLC (Figure 3). After purification by semi- preparative HPLC, the product was diluted with water + 5 mg ascorbic acid, trapped on a C18 cartridge and eluted with 1 mL ethanol.

Yield of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)-vinyl]-N- methylaniline: 43% (corrected for decay). Example 4 Synthesis and radiolabeling of 2d (2-[2-(2-{4-[(E)-2-{4-[(tert- butoxycarbonyl)(methyl)amino]phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl

4-(adamantan-1 -yl)benzenesulfonate)

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

To a stirred solution of 151 mg (0,330 mmol) tert-butyl-{4-[(E)-2-(4-{2-[2-(2- hydroxyethoxy)ethoxy]ethoxy}phenyl)vinyl]phenyl}methylcarbamate

(WO2006/066104), 4.03 mg (0,033 mmol) DMAP und 36.7 mg (363 mmol) triethylamine in 4 mL dichlormethane was added a solution of 97,4 mg (0,313 mmol) 4-(adamantan-1 -yl)benzene sulfonylchloride in 1 mL dichlormethane at 0°C. The reaction mixture was stirred at 0°C for 1 hour and over night at room temperature. 7.3 mg (0,072 mmol) triethylamin und 19.5 mg (0.062 mmol) 4- (adamantan-l -yl)benzenesulfonyl chloride were added to the reaction mixture. The reaction mixture was stirred at room temperature for 3 days. It was concentrated in vacuum. The crude product was purified using silica gel with ethyl acetate/hexane-gradient as mobile phase. The desired product 2d was obtained with 104 mg (0.142 mmol, 43.4% yield).

¹ H NMR (300 MHz, CDCI₃) δ ppm 1 .51 (s, 9 H), 1 .62 (s, 1 H), 1 .74 – 1 .91 (m, 6 H), 1 .94 (d, J=3.20 Hz, 6 H), 2.16 (br. s., 3 H), 3.31 (s, 3 H), 3.63 – 3.69 (m, 2 H), 3.69 – 3.73 (m, 2 H), 3.76 (dd, J=5.27, 4.52 Hz, 2 H), 3.89 (d, J=4.90 Hz, 2 H), 4.13 – 4.26 (m, 4 H), 6.95 (d, J=8.85 Hz, 2 H), 7.02 (d, J=8.29 Hz, 2 H), 7.25 (d, J=8.48 Hz, 2 H), 7.40 – 7.52 (m, 4 H), 7.55 (m, J=8.67 Hz, 2 H), 7.89 (m, J=8.67 Hz, 2 H)

MS (ESIpos): m/z = 732 (M+H)⁺

Radiolabeling was performed on a remote controlled synthesis module (Tracerlab FX_N). Precursor 2d (2 mg) in 0.5 mL DMSO + 0.5 mL acetonitrile was treated with dried potassium carbonate/kryptofix/[F-18]fluoride complex for 6 min at 100 °C. 1 M HCI (1 mL) + 10 mg ascorbic acid was added and the mixture was heated for 4 min at 100 °C. 2M NaOH (0.5 mL), water (6 mL) and ethanol (1 mL) were added and the crude mixture was trapped on a C18 cartridge. The crude product mixture was eluted with acetonitrile and diluted with 0.1 M ammonium formiat buffer (1 mL) + 5 mg ascorbic acid. A sample of the crude product was taken and analyzed by analytical HPLC (Figure 4). After purification by semi- preparative HPLC, the product was diluted with water + 5 mg ascorbic acid, trapped on a C18 cartridge and eluted with 1 mL ethanol.

Yield of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)-vinyl]-N- methylaniline: 27% (corrected for decay).

Example 5 Synthesis and radiolabeling of 2e (2-[2-(2-{4-[(E)-2-{4-[(tert- butoxycarbonyl)(methyl)amino]phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl

4-cyanobenzenesulfonate)

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- ethoxy}phenyl)vinyl]-N-methylaniline

To a stirred solution of 151 mg (0.330 mmol) tert-butyl-{4-[(E)-2-(4-{2-[2-(2- hydroxyethoxy)ethoxy]ethoxy}phenyl)vinyl]phenyl}methylcarbamate

(WO2006/066104), 4.03 mg (0.033 mmol) DMAP und 36.7 mg (0.363 mmol) triethylamine in 4 mL dichlormethane was added a solution of 63.2 mg (0.313 mmol) 4-cyanobenzenesulfonyl chloride in 1 mL dichlormethane at 0°C. The reaction mixture was stirred over night and concentrated in vacuum. The crude product was purified using silica gel with ethyl acetate/hexane-gradient as mobile phase. The desired product 2e was obtained with 118 mg (0.190 mmol, 57.6 % yield).

¹ H NMR (400 MHz, CDCI₃) δ ppm 1 .47 (s, 9 H) 3.28 (s, 3 H) 3.58 – 3.63 (m, 2 H) 3.63 – 3.68 (m, 2 H) 3.70 – 3.75 (m, 2 H) 3.81 – 3.87 (m, 2 H) 4.1 1 – 4.18 (m, 2 H) 4.24 – 4.30 (m, 2 H) 6.91 (d, J=8.59 Hz, 2 H) 6.99 (dt, 2 H) 7.22 (d, J=8.34 Hz, 2 H) 7.39 – 7.50 (m, 4 H) 7.83 (m, J=8.59 Hz, 2 H) 7.98 – 8.1 1 (m, 2 H)

MS (ESIpos): m/z = 623 (M+H)⁺

Radiolabeling was performed on a remote controlled synthesis module (Tracerlab FXN). Precursor 2e (2 mg) in 0.5 mL DMSO + 0.5 mL acetonitrile was treated with dried potassium carbonate/kryptofix/[F-18]fluoride complex for 6 min at 100 °C. 1 M HCI (1 mL) + 10 mg ascorbic acid was added and the mixture was heated for 4 min at 100 °C. 2M NaOH (0.5 mL), water (6 mL) and ethanol (1 mL) were added and the crude mixture was trapped on a C18 cartridge. The crude product mixture was eluted with acetonitrile and diluted with 0.1 M ammonium formiat buffer (1 mL) + 5 mg ascorbic acid. A sample of the crude product was taken and analyzed by analytical HPLC (Figure 5). After purification by semi- preparative HPLC, the product was diluted with water + 5 mg ascorbic acid, trapped on a C18 cartridge and eluted with 1 mL ethanol.

Yield of 4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]ethoxy}phenyl)-vinyl]-N- methylaniline: 31 % (corrected for decay).

Example 6 Synthesis and radiolabeling of 2f (2-[2-(2-{4-[(E)-2-{4-[(tert- butoxycarbonyl)(methyl)amino]phenyl}vinyl]phenoxy}ethoxy)ethoxy]ethyl

2-nitrobenzenesulfonate)

4-[(E)-2-(4-{2-[2-(2-[F-18]fluoroethoxy)ethoxy]- eth oxy} phe nyl )vi ny I] -N -methyla n i I i ne

To a stirred solution of 200 mg (0.437 mmol) tert-butyl-{4-[(E)-2-(4-{2-[2-(2- hydroxyethoxy)ethoxy]ethoxy}phenyl)vinyl]phenyl}methylcarbamate

(WO2006/066104), 5.34 mg (0.044 mmol) DMAP und 47.5 mg (0.470 mmol) triethylamine in 4 mL dichlormethane was added a solution of 92 mg (0,415 mmol) 2-nitrobenzenesulfonyl chloride in 1 mL dichlormethane at 0°C. The reaction mixture was stirred over night and concentrated in vacuum. The crude product was purified with ethyl acetate/hexane-gradient as mobile phase using silica gel. The desired product 2f was obtained with 77 mg (0.1 19 mmol, 59.5 % yield). ¹ H NMR (400 MHz, CDCI₃) δ ppm 1 .39 (s, 9 H) 3.20 (s, 3 H) 3.55 – 3.63 (m, 4 H) 3.59 (m, 4 H) 3.69 – 3.74 (m, 2 H) 3.75 – 3.80 (m, 2 H) 4.06 (dd, J=5.68, 3.92 Hz,

2 H) 4.32 – 4.37 (m, 2 H) 6.80 – 6.84 (m, 2 H) 6.84 – 6.98 (dt, 2 H) 7.14 (d, J=8.59 Hz, 2 H) 7.35 (d, J=3.03 Hz, 2 H) 7.37 (d, J=2.78 Hz, 2 H) 7.62 – 7.74 (m,

3 H) 8.06 – 8.1 1 (m, 1 H)