JP2007126412A - Diagnostic agent for tissue proliferation potency - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent stable in vivo and useful for image diagnosis of cell proliferation reflecting DNA synthesis activity by staying in the cell by the phosphorylation with thymidine kinase 1 after passing through nucleoside transporter or integrated in a DNA. <P>SOLUTION: The diagnostic agent for the tissue proliferation potency contains a specific<SP>18</SP>F-labeled nucleoside compound or its pharmacologically permissible salt as an active component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to the use of a radioactive fluorine-labeled nucleoside derivative for the purpose of diagnosing tissue proliferating ability, and a labeled precursor thereof.

Positron emission tomography (PET) is a method of administering a compound labeled with an isotope that emits positron into a living body, and imaging the dynamics and metabolism in the living body using a positron camera from outside the body. This is a test method applied to the diagnosis of various diseases. In order to achieve this purpose, biological substances labeled with carbon isotopes ( ¹¹ C) can be used for PET, but their half-life (20.5 minutes) is short, so ¹¹ C is produced in the hospital. Therefore, rapid compound synthesis and purification are required, and its usefulness is limited. Other isotopes have shorter half-lives, with ¹³ N having a half-life of 10 minutes and ¹⁵ O having a shorter half-life of 2 minutes.

As a practically useful isotope, ¹⁸ F has a half-life of 110 minutes. This is sufficient time for the synthesis and purification of the radiolabeled compound and for administration to a human or animal subject. Furthermore, a relatively long half-life of ^{18 F} is away from the hospital, may allow the supply of ^{18 F-labeled} compound from a cyclotron other facilities. ^{18 F} disadvantage of, the biological material is a difficulty in designing and manufacturing method of the labeling precursor that utilizes ^{18 F} generated in the design, and the cyclotron of different fluorinated compounds efficiently.

For these reasons, the use of ¹⁸ F-labelled compounds in PET is limited to a few compounds. The most widely used PET diagnostic method is the diagnosis of malignant tumors using ¹⁸ F-fluorodeoxyglucose. ¹⁸ F-fluorodeoxyglucose utilizes the enhancement of sugar metabolism in malignant tumor cells, and reflects energy metabolism accompanying tumor cell growth. For this essential reason, ¹⁸ F-fluorodeoxyglucose has the disadvantage that it detects lesions such as inflammation and benign diseases and produces false positives, especially with regard to the early and accurate determination of therapeutic effects. On the other hand, if cell growth, which is the essence of malignant tumors, can be observed more directly, the problems of ¹⁸ F-fluorodeoxyglucose can be overcome, and research on radioisotope-labeled nucleoside derivatives has been conducted. I have been. From many research results, the ideal compound is incorporated into cells via a nucleic acid transport carrier, phosphorylated by thymidine kinase 1, and finally incorporated into DNA. It is known to be a compound that is resistant to the cleavage reaction of glycosidic bonds by thymidine phosphorylase that causes a rapid metabolic degradation reaction in the body. Recently, practically useful ¹⁸ F-labeled 3′-deoxy-3′-fluorothymidine has been synthesized, and high in vivo stability and accumulation in tumor tissues has been observed (Shields AF). Et al., Nature Med. 4, pp. 1334-1336 (1998)). However, since this compound is substituted with ¹⁸ F at the 3 ′ position necessary for phosphodiester phosphate bonding, it is not theoretically incorporated into DNA, and phosphorylation by thymidine kinase 1 which is an indicator of DNA synthesis is actually carried out. It is the main mechanism of intracellular accumulation and is not a drug that essentially reflects DNA synthesis.

1- (2-deoxy-2-fluoro-β-D-arabinofuranosyl) thymine (1- (2-deoxy-2-fluoro-β-D-arabinofuranosyl) thymine) introduced with ¹⁸ F at the 2 ′ position Is a compound that exhibits high stability in vivo and has been attempted to be used for imaging of the proliferative ability of a tumor (Sun H. et al., Eur. J. Nucl. Med. 32, pages 15-22 (2005). Sun H. et al., J. Nucl. Med., 46, 292-296 (2005)). However, this compound has low affinity for thymidine kinase 1, and is rather used for in vivo introduction and expression of a gene therapy vector using a specific phosphorylation reaction of human herpesvirus by thymidine kinase. (Allaudin MM et al., J. Nucl. Med. 45, 2063-2069 (2004)). On the other hand, the present inventor discloses a nucleoside derivative in WO2002 / 058740, and the present invention aims to find out the feasibility of a diagnostic agent for cell proliferation imaging using a nucleoside derivative having a structure different from this.
International Publication No. 02/058740 Pamphlet US Pat. No. 4,762,823 European Patent No. 0221925 International Publication No. 91/04982 Pamphlet Japanese National Patent Publication No. 5-505791 Shields A. F. Et al., Nature Med. 4, pp. 1334-1336 (1998) Sun H. Et al., Eur. J. et al. Nucl. Med. 32, pages 15-22 (2005) Sun H. Et al. Nucl. Med. 46, 292-296 (2005) Allaudin M.M. M.M. Et al. Nucl. Med. 45, 2063-2069 (2004) Griengel H. et al., J. Med. Chem. 30, pp. 1199-1204 (1987) Rahim S.G. et al., J. Med. Chem. 39, 789-795 (1996) Tjarks W.D. , Nucleosides Nucleotides Nucleic Acids 20, 695-698 (2001)

In view of the circumstances as described above, the present invention is a nucleoside derivative having a hydroxyl group at the 3 ′ position, which can be labeled with ¹⁸ F, having resistance to cleavage reaction of glycoside bond by thymidine phosphorylase, and nucleoside An object of the present invention is to provide a compound that is directly phosphorylated by thymidine kinase 1 after passing through the transporter and directly reflects DNA synthesis activity, and a method for producing the compound.

In order to achieve the above-mentioned object, the inventors synthesized various ¹⁸ F-labelable compounds and conducted earnest research on whether image evaluation of cell proliferation is possible. As a result, the following formula (I) was obtained. The present inventors have found that the radioactive fluorine-labeled nucleoside derivative possessed can be used for diagnostic imaging of cell proliferation, that is, tissue proliferation ability, and have completed the present invention.

That is, the present invention is an agent for diagnosing tissue growth ability, which contains an ¹⁸ F-labeled compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.

(In the formula (I), R ₁ is a methyl group or an ¹⁸ F-labeled fluoroalkyl substituent having 1 to 2 carbon atoms, R ₂ is hydrogen or an ¹⁸ F-labeled fluoroalkyl substituent having 1 to 6 carbon atoms, R ₃ Is oxygen or sulfur, R ₄ is hydrogen or fluorine, provided that both R ₁ and R ₂ are ¹⁸ F-labeled fluoroalkyl substituents, and R ₁ is a methyl group and R ₂ is hydrogen except for.)

The radiolabeled compound of the present invention is stable in vivo and passes through a nucleoside transporter, and then phosphorylated by thymidine kinase 1 and stays in the cell, or is incorporated into DNA and has DNA synthesis activity. Therefore, it is useful for diagnostic imaging of cell proliferation, that is, tissue proliferation ability.
Therefore, according to another aspect of the present invention, an effective amount of the ¹⁸ F-labeled compound represented by the above formula (I) or a pharmaceutically acceptable salt thereof is administered to a mammal, and then the distribution in vivo is imaged. An image diagnostic method for cell proliferation comprising the steps of: Here, the mammal includes a human.
In the present invention, the ¹⁸ F-labeled compound represented by the above formula (I) may be in the form of a salt or a hydrate or solvate thereof. Salts include those that are pharmaceutically acceptable such as salts with mineral acids such as hydrochloric acid or sulfate or organic acids such as acetic acid. In addition, the hydrate or solvate means one in which water molecules or solvent molecules are attached to the ¹⁸ F-labeled compound of the present invention or a salt thereof. Furthermore, various isomers such as tautomers can also be included in the compounds of the present invention.

In the formula (I), R ₁ is preferably a methyl group. As the _{R 2,} for ^{example, 18} F-labeled fluoromethyl ^{group, 18} F-labeled fluoroethyl ^{group, 18} F-labeled fluoropropyl ^{group, 18} F-labeled-Fluoro-butyl ^{group, 18} F-labeled fluoropentyl ^{group, 18} F-labeled-Fluoro-hexyl ¹⁸ F-labeled fluoroethyl group, ¹⁸ F-labeled fluoropropyl group, and ¹⁸ F-labeled fluoropentyl group are preferable. R ₃ is preferably oxygen, and R ₄ is preferably hydrogen. Particularly preferred compounds include compounds in which R ₁ is a methyl group, R ₂ is an ¹⁸ F-labeled fluoroethyl group, R ₃ is oxygen, and R ₄ is hydrogen. In the above formula (I), the fluorine of R ₄ is usually non-radioactive fluorine.

In the compound of the above formula (I), R ₁ is a fluoromethyl group, R ₂ is hydrogen, R ₃ is oxygen, R ₄ is hydrogen, the chemical structure and use as an anticancer agent and antiviral agent, ¹⁸ F The use as a diagnostic agent for herpes encephalitis PET as a labeling compound is already known (US Pat. No. 4,762,823; European Patent 0221925).
In addition, among the compounds of the above formula (I), the chemical structure of a compound in which R ₁ is a fluoroethyl group, R ₂ is hydrogen, R ₃ is oxygen, and R ₄ is hydrogen and its use as an antiviral agent is already known ( Griengel H. et al., J. Med. Chem. 30, 1199-1204 (1987)). In addition, R ₁ is a fluoromethyl group or a fluoroethyl group, R ₂ is hydrogen, R ₃ is sulfur, and hydrogen is introduced into R _4. Already known (International Publication No. WO9104982; JP-T-5-505791; Rahim S. G. et al., J. Med. Chem. 39, pages 789-795 (1996)). However, its use as a radioactive fluorine-labeled compound and a radiographic diagnostic agent is not known.

Further, among the compounds of the above formula (I), R ₁ is a methyl group, R ₂ is a fluoromethyl group or fluoroethyl group, R ₃ is oxygen, and R ₄ is hydrogen. Is already known (Tjarks W. et al., Nucleosides Nucleotides Nucleic Acids 20, 695-698 (2001)). However, its use as a radioactive fluorine-labeled compound and a radioactive diagnostic imaging agent has not been known so far.

The radioactive fluorine-labeled compound of the above formula (I) can be synthesized by, for example, two kinds of methods shown in FIG. 1 (FIG. 1). One is to prepare a labeling precursor in which an alkyl group having an appropriate length having a leaving group at the ¹⁸ F introduction site is introduced at the 5th or 3rd position. The hydroxyl group is protected with a protecting group, and this and ¹⁸ F ions produced by cyclotron are reacted in an organic solvent in the presence of a phase transfer catalyst ([ ¹⁸ F] Fluorination), followed by deprotection ( This is a method of deprotection (Method 1). Of the radioactive fluorine-labeled compounds of the above formula, a compound having a fluoroalkyl group at the 3-position replaces only one leaving group of an alkyl group having a leaving group at two positions with ¹⁸ F ([[ ¹⁸ F] Fluorination), and the other leaving group can be used to synthesize a derivative of thymidine by substitution by a nucleophilic substitution reaction (Method 2).

Thus, according to another aspect of the present invention, a nucleoside derivative represented by the following formula (II) is provided as a labeling precursor.

(In the formula (II), R ₁ is an alkyl substituent having 1 to 2 carbon atoms having a methyl group or a leaving group, R ₂ is an alkyl substituent having 1 to 6 carbon atoms having hydrogen or a leaving group, R ₃ is oxygen or sulfur, R ₄ is hydrogen or fluorine, R ₅ is a protecting group, provided that both R ₁ and R ₂ are alkyl substituents having 1 to 6 carbon atoms having a leaving group. And R ₁ is a methyl group and R ₂ is hydrogen.)

In formula (II), R ₁ is preferably an alkyl substituent of 1 to 2 carbon atoms having a leaving group selected from the group consisting of a methyl group or a tosyl group, a mesyl group and a triflate group, Of these, a methyl group is particularly preferred.
In formula (II), R ₂ is preferably an alkyl substituent of 1 to 6 carbon atoms having a leaving group selected from the group consisting of hydrogen or a tosyl group, a mesyl group and a triflate group, An alkyl substituent selected from the group consisting of an ethyl group having a leaving group, a propyl group having a leaving group, and a pentyl group having a leaving group is more preferred, and an ethyl group having a leaving group is particularly preferred. The leaving group is preferably a tosyl group.

In formula (II), R ₅ is preferably a protecting group selected from the group consisting of a toluyl group, a 4 ′, 4′-dimethoxytrityl group, a trityl group and a benzyl group, and among them, a tolyl group is particularly preferable.
In formula (II), R ₃ is preferably oxygen, and R ₄ is preferably hydrogen.

In the present invention, by reacting a labeling precursor represented by the above formula (II) and ¹⁸ F ions produced by a cyclotron in an organic solvent in the presence of a phase transfer catalyst, the radioactive fluorine labeled compound of the above formula (I) Can be manufactured.
The dosage and administration route of the diagnostic imaging agent of the present invention should be selected according to the target disease and purpose of use, but when used as a diagnostic agent for tissue growth ability, for example, 37 MBq to 740 MBq, preferably Administer 111 MBq to 370 MBq of radioactivity. Usually, it is administered intravenously, but in some cases, administration routes other than intravenously may be selected, for example, intraarterial, intraperitoneal, or directly into the affected area such as a tumor.

In the present invention, the diagnosis of tissue growth ability is exemplified by diagnosis of proliferation, regeneration, transplantation or viral infection accompanied by pathological growth.
Diagnosis of growth accompanied by pathological growth includes, for example, diagnosis of proliferative inflammation, benign tumor or malignant tumor. Diagnosis of proliferative inflammation includes, for example, diagnosis relating to determination of rheumatoid arthritis activity and therapeutic effect. Diagnosis of a benign tumor includes, for example, diagnosis related to local diagnosis / activity and determination of therapeutic effect. Diagnosis of a malignant tumor includes, for example, a diagnosis of localization and progress of primary and metastatic malignant tumors, diagnosis of malignancy, and determination of therapeutic effect. Examples of benign tumors include prostatic hyperplasia, endometrial hyperplasia (cystic adenopathy / uterine adenomyosis / uterine fibroid), ovarian tumor (cyst adenoma), mammary gland (mammopathy / fibrofibroma adenoma), and pituitary gland. Examples include adenoma, craniopharyngioma, thyroid adenoma, adrenocortical adenoma, and pheochromocytoma. Examples of malignant tumors include malignant lymphoma (Hodgkin's disease / non-Hodgkin's lymphoma), pharyngeal cancer, lung cancer, esophageal cancer, stomach cancer, colon cancer, liver cancer, pancreatic cancer, kidney tumor (kidney cancer / nephroblastoma), bladder tumor , Prostate cancer, testicular cancer, uterine cancer, ovarian cancer, breast cancer, thyroid cancer, neuroblastoma, brain tumor (primary brain tumor / metastatic brain tumor), rhabdomyosarcoma, bone tumor (bone meat type / metastatic bone tumor) , Kaposi's sarcoma, and malignant melanoma.

Examples of the diagnosis of regeneration accompanied by pathological proliferation include functional diagnosis of physiological regeneration of blood and diagnosis of pathological regeneration that occurs when blood cells and the like are pathologically lost. Specifically, anticancer agents Evaluation of the physiological hematopoietic function of the bone marrow at the time of treatment or diagnosis of the pathological function of the bone marrow in aplastic anemia.

Diagnosis of transplantation with pathological growth is exemplified by bone marrow transplantation of hematological tumor patients and ultra-high-dose chemotherapy of anticancer drugs. Specifically, bone marrow transplant cell engraftment / proliferation in bone marrow transplantation Functional diagnosis is included.

Diagnosis of viral infection with pathological growth includes, for example, herpes simplex virus type 1 or type 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus or human immunodeficiency virus infection, Diagnosis of viral infection site and proliferation in central nervous system infections (such as viral infectious encephalitis or meningitis) by herpes simplex virus type 1 or type 2 or human immunodeficiency virus.

The radiofluorine-labeled nucleoside derivative of the present invention is stable in vivo, passes through a nucleoside transporter, is phosphorylated by thymidine kinase 1 and stays in the cell, or is incorporated into DNA to synthesize DNA. Since the activity is reflected, it is useful for diagnostic imaging of cell proliferation.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, the meaning of the symbol used in this specification is as follows.
DMF: dimethylformamide,
TBAF: Tetra-n-butylammonium fluoride
THF: tetrahydrofuran,
DMAP: 4-dimethylaminopyridine,
FMAU: 1- (2-deoxy-2-fluoro-β-D-arabinofuranosyl) thymine,
PPh ₃ : triphenylphosphine,
NBS: N-bromosuccinimide,
HPLC: High performance liquid chromatography.

Example 1 (NFT202)

N ⁸ - (2-fluoroethyl) - thymidine ^{(N 8 - (2-Fluoroethyl} ) -thymidine) (2)
Compound 1 (3.6 g, 17 mmol) synthesized according to the method of WF Edgell et al. (J. Am. Chem. Soc., 77, 4899 (1955)) and acetone (acetone) of potassium carbonate (4.6 g, 33 mmol) Thymidine (2.0 g, 8.3 mmol) was added to 500 mL of a mixed solution of DMF (1: 1), and the mixture was stirred at 50 ° C. for 7 hours. After concentrating the solvent, the residue was purified by silica gel column chromatography (SiO ₂ , chloroform: methanol = 5: 1). Compound 2 (2.2 g, 94%) was obtained as a white solid.

¹ H NMR (CD ₃ OD, 500 MHz) δ 7.85 (s, 1H, H-5), 6.29 (t, H-1 ', J _{1', 2'a} = J _{1 ', 2'b} = 5.6 Hz ), 4.62, 4.53 (each t, each 1H, H-2 "), 4.39 (m, 1H, H-3 '), 4.25 (m, 2H, H-1"), 3.91 (dd, 1H, H- 5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 9.6 Hz), 3.80 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5'b, 5'a} = 9.6 Hz), 3.72 (m, 1H, H-4 '), 2.27 (ddd, 1H, H-2'a, J _{2'a, 3'} = 2.8, J _{2'a , 1 '} = 6.0, J _{2'a, 2'b} = 10.8 Hz), 2.21 (m, 1H, H-2'b)), 1.89 (s, 3H, 5-CH ₃ ).

Example 2 (NFT203)

N ⁸ - (3- fluoropropyl) - thymidine ^{(N 8 - (3-Fluoropropyl} ) -thymidine) (4: NFT203)
Under an argon stream, thymidine (1.5 g, 6.2 mmol) was added to THF 40 mL of commercially available compound 3 (5.0 g, 36 mmol) and TBAF (1M THF solution 62 mL, 62 mmol), and stirred at room temperature for 1 hour. After concentrating the solvent, the residue was purified by silica gel column chromatography (SiO ₂ , chloroform: methanol = 5: 1). Compound 2 (2.0 g, 100%) was obtained as a white solid.

¹ H NMR (CD ₃ OD, 500 MHz) δ 7.82 (s, 1H, H-5), 6.28 (t, H-1 ', J _{1', 2'a} = J _{1 ', 2'b} = 5.6 Hz ), 4.51, 4.42 (each t, each 1H, H-2 "), 4.39 (m, 1H, H-3 '), 4.04 (m, 2H, H-1"), 3.91 (dd, 1H, H- 5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 9.6 Hz), 3.80 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5'b, 5'a} = 9.6 Hz), 3.72 (m, 1H, H-4 '), 2.27 (ddd, 1H, H-2'a, J _{2'a, 3'} = 2.8, J _{2'a , 1 '} = 6.0, J _{2'a, 2'b} = 10.8 Hz), 2.21 (m, 1H, H-2'b), 1.95 (m, 1H, H-2``), 1.89 (s, 3H , 5-CH ₃ ).

Example 3 (NFT401)

1,6-Hexanediol ditosylate (6)
Under an argon atmosphere, a solution of tosyl chloride (TsCl) (4.91 g, 2.5 mmol) and DMAP (3.05 g, 25 mmol) in acetonitrile solution (50 mL) (1,6-hexanediol) (1. 18 mg, 10 mmol) and triethylamine (3.48 g, 25 mmol) in acetonitrile were added and stirred at room temperature for 2 hours. The precipitated solid was filtered, and the filtrate was diluted with ethyl acetate (ca. 500 mL), and washed with water (500 mL) and saturated brine (500 mL). After drying over anhydrous sodium sulfate and concentration, the residue was purified by silica gel column chromatography (SiO2, hexane: ethyl acetate = 2: 1). Compound 6 (2.4 g, 5.6 mmol, 56%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 400 MHz) δ 7.77 (m, 4H, Tol), 7.35 (m, 4H, Tol), 3.98 (t, 4H, H-1, 6, J = 4.8 Hz), 2.45 (s , 6H, Tol-CH ₃ ), 1.60 (m, 4H, H-2, 5), 1.27 (m, 4H, H-3, 4).

N ⁸ - (6- fluoro-1-hexyl) - thymidine ^{(N 8 - (6-Fluoro} -1-hexyl) -thymidine) (7: NFT401)
Under an argon atmosphere, potassium fluoride (50 mg, 0.6 mmol), cryptofix [2.2.2] (226 mg, 0.6 mmol) was dissolved in acetonitrile (1.5 mL), and compound 6 (231 mg, 0.5 mmol) was dissolved. Of acetonitrile (1.0 mL) was added, and the mixture was stirred at 80 ° C. for 1 hour. To this solution, a DMF solution of thymidine (121 mg, 0.5 mmol) and cesium carbonate (195 mg, 0.6 mmol) was added, and the mixture was further stirred at 80 ° C. for 1.5 hours, then allowed to cool and concentrated. The residue was purified by silica gel column chromatography (SiO2, chloroform: methanol = 20: 1) to obtain Compound 7 (80 mg, 0.23 mmol, 46%) as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ7.83 (s, 1H, H-6), 6.30 (t, H-1 ', J _{1', 2'a} = J _{1 ', 2'b} = 5.6 Hz ), 4.45, 4.36 (each t, each 1H, H-6 "), 4.39 (m, 1H, H-3 '), 3.92 (m, 2H, H-1"), 3.80 (dd, 1H, H- 5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 9.6 Hz), 3.73 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5'b, 5'a} = 9.6 Hz), 3.56 (m, 1H, H-4 '), 2.28 (ddd, 1H, H-2'a, J _{2'a, 3'} = 2.8, J _{2'a , 1 '} = 6.0, J _{2'a, 2'b} = 10.8 Hz), 2.20 (m, 1H, H-2'b), 1.90 (s, 3H, 5-CH ₃ ), 1.72 to 1.59 (m, 4H, H-2 '', 5 ''), 1.46 to 1.35 (m, 4H, H-3 '', 4 '').

Example 4 (NFTS202)

1- (2-deoxy-4-thio - erythro - pentofuranosyl) ^-N 3 - (2-fluoroethyl) - thymine (1- (2-Deoxy-4 -thio-erythro-pentofuranosyl) -N 3 - ( 2-fluoroethyl) -thymine) (9: NFTS202)
Compound 8 (129 mg, 0. 2) synthesized according to the method of MR Dyson et al. And the method of GP Otter et al. (Carbohydrate Research, 216, 237 (1991): J. Chem. Soc. Perkin. Trans., 2, 2343 (1998)). 5 mmol) and commercially available 2-fluoro-1-bromoehtane (127 mg, 1 mmol) were added to a DMF solution of cesium carbonate (195 mg, 0.6 mmol), and the mixture was stirred at 80 ° C. for 10 hours. Thereafter, the mixture was allowed to cool and concentrated. The residue was purified by silica gel column chromatography (SiO2, chloroform: methanol = 20: 1) to obtain Compound 9 (122 mg, 0.4 mmol, 80%) as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 6.60 (dd, H-1 ', J _{1', 2'a} = 4.6, J _{1 ', 2'b} = 7.0 Hz), 5.74 (m, 1H , H-3 '), 4.81 (dd, 1H, H-5'a, J _{5'a, 4'} = 2.4, J _{5'a, 5'b} = 10.0 Hz),), 4.54 4.77 (m, 2H, H-5'b, H-1 "b), 4.60 (m, 1H, H-1" a), 4.55 (m, 1H, H-4 '), 4.35 (m, 1H, H-2``a), 4.33 (m, 1H, H-2''a), 2.99 (ddd, 1H, H-2'a, J _{2'a, 3 '} = 1.2, J _{2' a, 1 '} = 4.6, J _{2'a, 2'b} = 11.2 Hz), 2.83 (m, 1H, 2 ”-OH), 2.30 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 5.2, J _{2'b, 1'} = 7.0, J _{2'b, 2'a} = 11.2 Hz), 1.65 (s, 3H, 5-CH ₃ );

Example 5 (NFAU202)

1- (2 -Deoxy-2-fluoro-β-D- arabinofuranosyl) -N ^3- (2-fluoroethyl) -thymine (1- (2-Deoxy-2-fluoro-β-D-arabinofuranosyl) -N ^3- (2-fluoroethyl) -thymine) (10: NFAU202)
Acetone of Compound 1 (541 mg, 2.5 mmol) and potassium carbonate (630 mg, 4.6 mmol) synthesized according to the method of WF Edgell et al. (J. Am. Chem. Soc., 77, 4899 (1955)) under an argon stream. FMAU (323 mg, 1.2 mmol) synthesized by the method of CJWilds and M. J. Damha et al. (Nucleic Acids Research, 28, 3625 (2000)) was added to 30 mL of a mixed solution of DMF and DMF (1: 1). Stir at 8 ° C. for 8 hours. After concentrating the solvent, the residue was purified by silica gel column chromatography (SiO ₂ , chloroform: methanol = 5: 1). Compound 10 (272 mg, 72%) was obtained as a white solid.

¹ H NMR (CD ₃ OD, 500 MHz) δ 7.73 (s, 1H, H-5), 6.20 (dd, 1H, H-1 ', J _{1', F} = 17 Hz, J _{1 ', 2'} = 4.0 Hz), 5.03 (dt, 1H, H-2 ', J _{2', F} = 52 Hz, J _{1 ', 2'} = J _{2 ', 3'} = 2.5 Hz), 4.58 (dd, 2H, H- <sub>2``</sub> , J <sub>2 '', F</sub> = 47 Hz, J <sub>1 ', 2'b</sub> = 5.0 Hz), 4.32 (m, 1H, H-3'), 4.28 (m, 2H, H-1``) , 3.91 (m, 1H, H-4 '), 3.86 (dd, 1H, H-5'a, J _{5'a, 4'} = 12.0, J _{5'a, 5'b} = 4.0 Hz), 3.76 ( dd, 1H, H-5'b, J _{5'b, 4 '} = 12.0, J _{5'b, 5'a} = 4.0 Hz), 2.66 (s, 3H, 5-CH ₃ ).

Example 6
3 ', 5'-Di-O-Toluoyl-N ⁸ -(2-p-Toluenesulfoxyethyl) -thymine (3 ', 5'-Di-O-toluoyl-N ⁸ -(2-p-toluenesulfoxyethyl) -thymine)

3 ′, 5′-Di-O-toluoylthymidine (3 ′, 5′-Di-O-toluoylthymidine) (12)
Toluidine chloride (TolCl) (2.1 mL, 16.1 mmol) was added to a pyridine solution (80 mL) of thymidine (1.95 g, 8 mmol) in an argon atmosphere, and the mixture was stirred at room temperature for 16 hours. The reaction solution was poured into ice water and stirred for 5 minutes, and the precipitated solid was collected by filtration. After washing with water, silica gel column chromatography (SiO _2, hexane: ethyl acetate = 3: 1). Compound 12 (3.4 g, 7.1 mmol, 89%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 8.45 (bs, 1H, NH), 7.96 (m, 4H, o-Tol), 7.26 (m, 5H, H-6, m-Tol), 6.46 (dd, H-1 ', J _{1', 2'a} = 4.4, J _{1 ', 2'b} = 6.8 Hz), 5.64 (m, 1H, H-3'), 4.79 (dd, 1H, H-5'a , J _{5'a, 4 '} = 2.8, J _{5'a, 5'b} = 9.6 Hz),), 4.65 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5 'b, 5'a = 9.6 Hz)} , 5.53 (m, 1H, H-4'), 2.70 (ddd, 1H, H-2'a, J 2'a, 3 '= 1.2, J 2'a, _{1 '} = 4.4, J _{2'a, 2'b} = 11.2 Hz), 2.44, 2.43 (each s, each 3H, Tol-CH ₃ ), 2.31 (ddd, 1H, H-2'b, J _{2'b , 3 '} = 5.2, J _{2'b, 1'} = 6.8, J _{2'b, 2'a} = 11.2 Hz), 1.62 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz ) δ 166.10, 166.04, 163.06, 150.11, 144.64, 134.44, 129.85, 129.53, 129.51, 129.32, 126.54, 126.25, 111.64, 84.91, 82.82, 77.28, 74.91, 64.18, 38.08, 21.76, 21.72, 12.13.

3', 5'-di -O- toluoyl ^-N 8 - (2-hydroxyethyl) - thymidine ^{(3', 5'-Di-O} -toluoyl-N 8 - (2-hydorxyethyl) -thymidine) (13)
Under an argon atmosphere, compound 12 (3.7 g, 8 mmol) was dissolved in THF (120 mL), TBAF (1.0 M in THF, 80 mL, 80 mmol), 2-bromoethanol (14 mL, 0.2 mol) And stirred at room temperature for 2 hours. The reaction solution was poured into ice water and stirred for 5 minutes, and the precipitated solid was collected by filtration. The solid was put into water and stirred for 15 minutes, and then collected again by filtration and dried by a desiccator to obtain Compound 13 (3.3 g, 6.5 mmol, 81%) as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 7.96 (m, 4H, o-Tol), 7.26 (m, 5H, H-6, m-Tol), 6.48 (dd, H-1 ', J _{1', 2'a} = 4.4, J _{1 ', 2'b} = 6.8 Hz), 5.64 (m, 1H, H-3'), 4.79 (dd, 1H, H-5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 9.6 Hz),), 4.66 (dd, 1H, H-5'b, J _{5'b, 4 '} = 2.8, J _{5'b, 5'a} = 9.6 Hz ), 5.53 (m, 1H, H-4 '), 4.21 (m, 1H, H-1''), 3.86 (m, 1H, H-2''), 2.72 (ddd, 1H, H-2'a, J _{2'a, 3 '} = 1.2, J _{2'a, 1'} = 4.4, J _{2'a, 2'b} = 11.2 Hz), 2.53 (m, 1H, 2 "-OH), 2.44, 2.43 (each s, each 3H, Tol-CH ₃ ), 2.31 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 5.2, J _{2'b, 1'} = 6.8, J _{2'b, 2 ' a} = 11.2 Hz), 1.65 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.06, 166.34, 164.12, 151.56, 144.61, 132.93, 129.81, 129.51, 129.48, 129.30, 126.51 , 126.25, 110.99, 85.78, 82.85, 77.25, 74.89, 64.13, 61.79, 43.97, 38.19, 21.73, 21.69, 12.84.

3', 5'-di -O- toluoyl ^-N 8 - (2-p- toluenesulfonyl carboxyethyl) - thymine (3', 5'-Di-O -toluoyl-N 8 - (2-p-toluenesulfoxyethyl) -thymine) (14)
Tosyl chloride (229 mg, 1.2 mmol) was added to a pyridine solution (10 mL) of compound 13 (522 mg, 1.0 mmol) in an argon atmosphere, and the mixture was stirred at 0 ° C. for 16 hours. The mixture was diluted with chloroform (ca. 50 mL), and washed with 1N hydrochloric acid (40 mL), water (40 mL), saturated aqueous sodium hydrogen carbonate (40 mL), and saturated brine (40 mL). After drying over anhydrous sodium sulfate and concentrated, the residue was purified by silica gel column chromatography (SiO _2, hexane: ethyl acetate = 1: 1). Compound 14 (500 mg, 0.74 mmol, 74%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 7.96 (m, 4H, o-Tol), 7.69 (m, 2H, o-Ts), 7.26 (m, 7H, H-6, m-Tol, m-Ts ), 6.44 (dd, H-1 ', J _{1', 2'a} = 4.4, J _{1 ', 2'b} = 6.8 Hz), 5.63 (m, 1H, H-3'), 4.81 (dd, 1H , H-5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 10.0 Hz), 4.65 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5'b, 5'a} = 10.0 Hz), 5.54 (m, 1H, H-4 '), 4.27 (m, 1H, H-2 "), 4.22 (m, 1H, H-1") , 2.71 (ddd, 1H, H-2'a, J _{2'a, 3 '} = 1.2, J _{2'a, 1'} = 4.4, J _{2'a, 2'b} = 11.2 Hz), 2.53 (m, 1H, H-2 "), 2.45, 2.42, 2.40 (each s, each 3H, Ts-CH _3, Tol-CH ₃ ), 2.28 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 5.2, J _{2'b, 1 '} = 6.8, J _{2'b, 2'a} = 11.2 Hz), 1.58 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.05 , 166.12, 162.81, 150.60, 144.70, 144.57, 144.55, 132.86, 132.77, 129.79, 129.50, 129.46, 129.28, 127.79, 126.48, 126.25, 110.52, 85.72, 82.86, 77.21, 74.89, 66.30, 64.14, 39.73, 38.09 , 21.66, 21.55, 12.75.

Example 7
3 ', 5'-Di-O-Toluoyl-N ⁸ -(2-Methanesulfoxyethyl) -thymidine (3 ', 5'-Di-O-toluonyl-N ⁸ -(2-methansulfoxyethyl) -thymidine)

3', 5'-di -O- toluoyl ^-N 8 - (2-methanesulfonyl carboxyethyl) - thymidine ^{(3', 5'-Di-O} -toluonyl-N 8 - (2-methansulfoxyethyl) -thymidine) ( 15)
Under an argon atmosphere, mesyl chloride (MsCl) (63 μg, 0.81 mmol) was added to a pyridine solution (6.7 mL) of compound 13 (350 mg, 0.67 mmol), and the mixture was stirred at 0 ° C. for 16 hours. The mixture was diluted with chloroform (ca. 50 mL), and washed with 1N hydrochloric acid (40 mL), water (40 mL), saturated aqueous sodium hydrogen carbonate (40 mL), and saturated brine (40 mL). After drying over anhydrous sodium sulfate and concentrated, the residue was purified by silica gel column chromatography (SiO _2, hexane: ethyl acetate = 3: 1). Compound 15 (312 mg, 0.52 mmol, 78%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 7.93 (m, 4H, o-Tol), 7.28 (m, 5H, H-6, m-Tol), 6.46 (dd, H-1 ', J _{1', 2'a} = 5.5, J _{1 ', 2'b} = 8.5 Hz), 5.63 (m, 1H, H-3'), 4.78 (dd, 1H, H-5'a, J _{5'a, 4 '} = 2.5, J _{5'a, 5'b} = 12.0 Hz), 4.65 (dd, 1H, H-5'b, J _{5'b, 4 '} = 4.0, J _{5'b, 5'a} = 12.0 Hz), 5.53 (m, 1H, H-4 '), 4.47 (m, 1H, H-2''), 4.31 (m, 1H, H-1''), 3.01 (s, 3H, Ms-CH ₃ ), 2.72 ( ddd, 1H, H-2'a, J _{2'a, 3 '} = J _{2'a, 1'} = 5.5, J _{2'a, 2'b} = 14.0 Hz), 2.43, 2.42 (each s, each 3H , Tol-CH ₃ ), 2.31 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 6.5, J _{2'b, 1'} = 8.5, J _{2'b, 2'a} = 14.0 Hz ), 1.64 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.04, 166.02, 163.04, 150.75, 144.56, 133.02, 129.79, 129.51, 129.45, 129.27, 126.49, 126.25, 110.67 , 85.80, 82.86, 74.88, 65.73, 64.18, 40.06, 38.09, 37.82, 21.71, 21.66, 21.55, 12.80.

Example 8
3 ', 5'-Di-O-Toluoyl-N ⁸ -(2-p-methoxyphenylsulfoxyethyl) -thymidine (3 ', 5'-Di-O-toluoyl-N ⁸ -(2-p-methoxyphenylsulfoxy) -thymidine)

3', 5'-di -O- toluoyl ^-N 8 - (2-p- methoxyphenyl sulphoxide ethyl) - thymidine ^{(3', 5'-Di-O} -toluoyl-N 8 - (2-p-methoxyphenylsulfoxyethyl ) -Thymidine) (16)
Under an argon atmosphere, paramethoxyphenylsulfonyl chloride (p-MeOPhSO ₂ Cl) (387 mg, 1.87 mmol) was added to a pyridine solution (15 mL) of compound 13 (816 mg, 1.56 mmol), and the mixture was stirred at 0 ° C. for 16 hours. The mixture was diluted with chloroform (ca. 150 mL), and washed with 1N hydrochloric acid (140 mL), water (140 mL), saturated aqueous sodium hydrogen carbonate (140 mL), and saturated brine (140 mL). After drying over anhydrous sodium sulfate and concentrated, the residue was purified by silica gel column chromatography (SiO _2, hexane: ethyl acetate = 3: 1). Compound 16 (227 mg, 0.33 mmol, 21%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 7.94 (m, 4H, o-Tol), 7.79 (m, 2H, o-ph), 7.26 (m, 5H, H-6, m-Tol), 6.95 ( m, 2H, m-Ts), 6.44 (dd, H-1 ', J _{1', 2'a} = 5.5, J _{1 ', 2'b} = 8.0 Hz), 5.63 (m, 1H, H-3' ), 4.80 (dd, 1H, H-5'a, J _{5'a, 4 '} = 2.5, J _{5'a, 5'b} = 12.0 Hz), 4.65 (dd, 1H, H-5'b, J _{5'b, 4 '} = 3.0, J _{5'b, 5'a} = 12.0 Hz), 5.53 (m, 1H, H-4'), 4.28-4.20 (m, 4H, H-1 ", 2") , 3.83 (s, 3H, Ph-CH ₃ ), 2.71 (ddd, 1H, H-2'a, J _{2'a, 3 '} = J _{2'a, 1'} = 5.5, J _{2'a, 2 ' b} = 14.0 Hz), 2.44, 2.42 (each s, each 3H, Tol-CH ₃ ), 2.28 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 6.0, J _{2'b, 1 '} = 8.0, J _{2'b, 2'a} = 14.0 Hz), 1.59 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.10, 166.07, 163.71, 162.86, 150.66, 144.62, 144.60, 132.84, 130.05, 129.85, 129.55, 129.51, 129.32, 127.33, 126.52, 126.30, 114.41, 110.61, 85.78, 82.89, 77.22, 74.94, 66.15, 64.20, 60.40, 55.64, 39.80, 38.14, 21.76, 2170 12.80.

Example 9
3 ', 5'-Di-O-Toluoyl-N ⁸ -(2-Bromoethyl) -thymidine (3 ', 5'-Di-O-toluoyl-N ⁸ -(2-bromoethyl) -thymidine)

3', 5'-di -O- toluoyl ^-N 8 - (2-bromoethyl) - thymidine ^{(3', 5'-Di-O} -toluoyl-N 8 - (2-bromoethyl) -thymidine) (17)
Under an argon atmosphere, PPh ₃ (314 mg, 1.2 mmol) and NBS (213 mg, 1.2 mmol) were added to a pyridine solution (10 mL) of compound 13 (552 mg, 1.0 mmol), and the mixture was stirred at room temperature for 30 minutes. The mixture was diluted with chloroform (ca. 100 mL), and washed with saturated aqueous sodium hydrogen carbonate (100 mL) and saturated brine (100 mL). After drying over anhydrous magnesium sulfate and concentration, the residue was purified by silica gel column chromatography (SiO2, hexane: ethyl acetate = 1: 1). Compound 17 (150 mg, 0.26 mmol, 26%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 500 MHz) δ 7.93 (m, 4H, o-Tol), 7.28 (m, 5H, H-6, m-Tol), 6.48 (dd, H-1 ', J _{1', 2'a} = 5.5, J _{1 ', 2'b} = 9.0 Hz), 5.64 (m, 1H, H-3'), 4.80 (dd, 1H, H-5'a, J _{5'a, 4 '} = 2.5, J _{5'a, 5'b} = 12.0 Hz), 4.65 (dd, 1H, H-5'b, J _{5'b, 4 '} = 3.5, J _{5'b, 5'a} = 12.0 Hz), 5.53 (m, 1H, H-4 '), 4.35 (m, 1H, H-1''), 3.54 (m, 1H, H-2''), 2.71 (ddd, 1H, H-2'a, J _{2 'a, 3'} = 1.0, J _{2'a, 1 '} = 5.5, J _{2'a, 2'b} = 14.0 Hz), 2.44, 2.43 (each s, each 3H, Tol-CH ₃ ), 2.31 (ddd , 1H, H-2'b, J _{2'b, 3 '} = 7.0, J _{2'b, 1'} = 9.0, J _{2'b, 2'a} = 14.0 Hz), 1.65 (s, 3H, 5- CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.07, 166.03, 162.79, 160.62, 150.64, 144.62, 144.59, 132.88, 129.81, 129.53, 129.48, 129.31, 126.53, 126.27, 110.84, 85.65, 82.82, 77.21 , 74.86, 64.10, 42.19, 38.11, 27.25, 21.74, 21.70, 12.83.

Example 10 ([ ¹⁸ F] NFT202)
^{N 8 - (2- [18 F} ] fluoroethyl) - Synthesis of thymidine ^{(Radiosynthesis of N 8 - (2-} [18 F] fluoroethyl) -thymidine ([18 F] NFT202)
A mixed solution of [ ¹⁸ F] fluoride aqueous solution (1580 MBq), 40 mmol / L cryptofix [2.2.2] acetonitrile solution (0.25 mL, 10 μmol), 66 mmol / L potassium carbonate aqueous solution (750 μL, 5 μmol). The mixture was concentrated using an aluminum block (110 ° C.) and azeotroped twice using acetonitrile (1 mL). A label precursor 14 (13.5 mg, 20 μmol) in acetonitrile (1 mL) was added, and the mixture was stirred at 130 ° C. for 5 minutes (step 1). Next, 1.0 mL (240 μmol) of 0.24 M sodium ethoxide / ethanol solution was added and allowed to stand at room temperature for 10 minutes, and then neutralized by adding 1.0 M aqueous sodium acetate solution (0.3 mL, 300 μmol) (step 2 ). After evaporating acetonitrile and ethanol using an aluminum block (110 ° C.), diluting with water (2.5 mL) and filtering (0.45 μ), the filtrate was purified using HPLC, and [ ¹⁸ F] NFT202 (73 .2MBq) was synthesized.

Purification; HPLC stationary phase: C18 column (300 x 30 mm, 10μ)
Mobile phase: Water: ethanol = 3: 1 (v / v)
Flow rate: 6.0 mL / min
Detector: NaI (Tl) scintillator, UV detector (254 nm)

Example 11
3 ', 5'-Di-O-Toluoyl-N ⁸ -(3-p-Toluenesulfoxy-1-propyl) -thymidine (3 ', 5'-Di-O-toluoyl-N ⁸ -(3-p-toluenesulfoxy-1-propyl) -thymidine)

3', 5'-di -O- toluoyl ^-N 8 - (3- hydroxy-1-propyl) - thymidine ^{(3', 5'-Di-O} -toluoyl-N 8 - (3-hydroxy-1-propyl ) -Thymidine) (18)
Under an argon atmosphere, Compound 12 (485 mg, 1.0 mmol) was dissolved in THF (10 mL), TBAF (1.0 M in THF, 10 mL, 10 mmol), 3-bromo-1-propanol (3-bromo-1-propanol) (2.8 mL, 30 mmol) was added and stirred at room temperature for 2 hours. The reaction solution was poured into ice water and stirred for 5 minutes, and the precipitated solid was collected by filtration. The solid was added to water and stirred for 15 minutes, and then collected again by filtration and dried by a desiccator to obtain Compound 18 (414 mg, 0.77 mmol, 77%) as a white solid.

¹ H NMR (CDCl ₃ , 400 MHz) δ 7.87 (m, 4H, o-Tol), 7.24-7.19 (m, 5H, H-6, m-Tol), 6.41 (dd, H-1 ', J _{1 ', 2'a} = 4.4, J _{1', 2'b} = 6.8 Hz), 5.56 (m, 1H, H-3 '), 4.73 (dd, 1H, H-5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 9.6 Hz),), 4.58 (dd, 1H, H-5'b, J _{5'b, 4'} = 2.8, J _{5'b, 5'a} = 9.6 Hz), 5.46 (m, 1H, H-4 '), 4.03 (m, 1H, H-1 "), 3.42 (m, 1H, H-3"), 3.19 (m, 1H, 2 "-OH ), 2.63 (ddd, 1H, H-2'a, J _{2'a, 3 '} = 1.2, J _{2'a, 1'} = 4.4, J _{2'a, 2'b} = 11.2 Hz), 2.37, 2.36 (each s, each 3H, Tol-CH ₃ ), 2.25 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 5.2, J _{2'b, 1'} = 6.8, J _{2'b, 2'a} = 11.2 Hz), 1.79 (m, 2H, H-2 ”), 1.58 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 171.13, 166.06, 166.01, 163.92 , 151.23, 144.62, 132.90, 129.80, 129.51, 129.46, 129.30, 126.52, 126.24, 110.83, 85.71, 82.85, 77.25, 74.83, 64.07, 60.37, 58.53, 38.19, 37.83, 30.47, 21.73, 14.69, 21.87, 14.18 .

3', 5'-di -O- toluoyl ^-N 8 - (3-p- toluene sulfoxylate-1-propyl) - thymidine (3', 5'-Di-O -toluoyl-N 8 - (3-p -Toluenesulfoxy-1-propyl) -thymidine) (19)
Tosyl chloride (117 mg, 0.6 mmol) was added to a pyridine solution (5 mL) of compound 18 (267 mg, 0.5 mmol) under an argon atmosphere, and the mixture was stirred at 0 ° C. for 16 hours. The mixture was diluted with chloroform (ca. 20 mL), and washed with 1N hydrochloric acid (15 mL), water (15 mL), saturated aqueous sodium hydrogen carbonate (15 mL), and saturated brine (15 mL). After drying over anhydrous sodium sulfate and concentration, the residue was purified by silica gel column chromatography (SiO2, hexane: ethyl acetate = 1: 1). Compound 19 (205 mg, 0.30 mmol, 60%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 400 MHz) δ 7.87 (m, 4H, o-Tol), 7.71 (m, 2H, o-Ts), 7.26-7.19 (m, 7H, H-6, m-Tol, m -Ts), 6.40 (dd, H-1 ', J _{1', 2'a} = 4.4, J _{1 ', 2'b} = 6.8 Hz), 5.56 (m, 1H, H-3'), 4.72 (dd , 1H, H-5'a, J _{5'a, 4 '} = 2.4, J _{5'a, 5'b} = 10.0 Hz), 4.58 (dd, 1H, H-5'b, J _{5'b, 4 '} = 2.8, J _{5'b, 5'a} = 10.0 Hz), 5.45 (m, 1H, H-4'), 4.02 (t, 1H, H-3 ”, J _{3”, 2 ”} = 5.2 Hz) , 3.91 (m, 1H, H-1 ”), 2.64 (ddd, 1H, H-2'a, J _{2'a, 3 '} = 1.2, J _{2'a, 1'} = 4.4, J _{2'a, 2'b} = 11.2 Hz), 2.37, 2.36, 2.35 (each s, each 3H, Ts-CH _3, Tol-CH ₃ ), 2.25 (ddd, 1H, H-2'b, J _{2'b, 3 '} = 5.2, J _{2'b, 1 '} = 6.8, J _{2'b, 2'a} = 11.2 Hz), 1.89 (m, 1H, H-2 ”), 1.54 (s, 3H, 5-CH ₃ ); ¹³ C NMR (CDCl ₃ , 100 MHz) δ 166.08, 163.03, 150.71, 144.69, 144.59, 144.54, 132.99, 132.65, 129.82, 129.81, 129.56, 129.48, 129.30, 127.94, 126.54, 126.29, 110.72, 85.62, 82.78, 77.25 , 74.92, 86.53, 64.15, 38.16, 38.10, 27.15, 21.74, 21.69, 21.62, 12.83.

Example 12 ([ ¹⁸ F] NFT203)
^{N 8 - (3- [18 F} ] fluoropropyl) - Synthesis of thymidine ^{(Radiosynthesis of N 8 - (3-} [18 F] fluoropropyl) -thymidine) ([18 F] NFT203)
[ ¹⁸ F] Fluoride aqueous solution (1666 MBq), 40 mmol / L cryptofix [2.2.2] acetonitrile solution (1.0 mL, 40 μmol), 66 mmol / L potassium carbonate aqueous solution (0.3 μL, 20 μmol) The solution was concentrated using an aluminum block (110 ° C.) and azeotroped twice using acetonitrile (1.0 mL). A label precursor 19 (27.6 mg, 40 μmol) in acetonitrile (1.0 mL) was added, and the mixture was stirred at 80 ° C. for 10 minutes (step 1). Next, 1.0 mL (240 μmol) of 0.24 M sodium ethoxide / ethanol solution was added and allowed to stand at room temperature for 10 minutes, and then neutralized by adding 1.0 M aqueous sodium acetate solution (0.3 mL, 300 μmol) (step 2 ). Acetonitrile and ethanol were evaporated using an aluminum block (110 ° C.), diluted with water (2.5 mL), filtered (0.45 μ), purified using HPLC, and [ ¹⁸ F] NFT203 (167.2 MBq). ) Was synthesized.

Purification; HPLC stationary phase: C18 column (300 x 30 mm, 10μ)
Mobile phase: Water: Ethanol = 3: 1 (v / v)
Flow rate: 5.0 ml / ml
Detector: NaI (Tl) scintillator, UV detector (254 nm)

Example 13
1,6-hexanediol ditosylate

1,6-hexanediol ditosylate (20)
Under an argon atmosphere, 1,6-hexanediol (1.18 mg, 10 mmol) was added to an acetonitrile solution (50 mL) of tosyl chloride (4.91 g, 2.5 mmol) and DMAP (3.05 g, 25 mmol). ), Triethylamine (3.48 g, 25 mmol) in acetonitrile was added and stirred at room temperature for 2 hours. The precipitated solid was filtered, and the filtrate was diluted with ethyl acetate (ca. 500 mL), and washed with water (500 mL) and saturated brine (500 mL). After drying over anhydrous sodium sulfate and concentration, the residue was purified by silica gel column chromatography (SiO2, hexane: ethyl acetate = 2: 1). Compound 20 (2.4 g, 5.6 mmol, 56%) was obtained as a white solid.

¹ H NMR (CDCl ₃ , 400 MHz) δ 7.77 (m, 4H, Tol), 7.35 (m, 4H, Tol), 3.98 (t, 4H, H-1, 6, J = 4.8 Hz), 2.45 (s , 6H, Tol-CH ₃ ), 1.60 (m, 4H, H-2, 5), 1.27 (m, 4H, H-3, 4).

Example 14 ([ ¹⁸ F] NFT401)
^{N 8 - (6- [18 F} ] fluoro-hexyl) - Synthesis of thymidine ^{(Radiosynthesis of N 8 - (6-} [18 F] fluorohexyl) -thymidine) ([18 F] NFT401)
[ ¹⁸ F] Fluoride aqueous solution (3630 MBq), 40 mmol / L cryptofix [2.2.2] acetonitrile solution (1.2 mL, 53 μmol), 66 mmol / L potassium carbonate aqueous solution (0.3 mL, 20 μmol) The solution was concentrated using an aluminum block (110 ° C.) and azeotroped twice using acetonitrile (1 mL). A label precursor 20 (17.0 mg, 40 μmol) in acetonitrile (1 mL) was added, and the mixture was stirred at 80 ° C. for 10 minutes (step 1). Next, a DMF solution (0.5 mL) of thymidine (19.3 mg, 80 μmol) and a DMF suspension (0.5 mL) of cesium carbonate (52.1 mg, 160 μmol) were added, and 15 ° C. was added at 15 ° C. Stir for minutes (step 2). Acetonitrile was evaporated using an aluminum block (110 ° C.), diluted with water (2.5 mL), and purified using HPLC to synthesize [ ¹⁸ F] NFT401 (145.1 MBq).

Purification; HPLC stationary phase: C18 column (300 x 30 mm, 10μ)
Mobile phase: Water: ethanol = 3: 1 (v / v)
Flow rate: 5.0 mL / min
Detector: NaI (Tl) scintillator, UV detector (254 nm)

Example 15 (NFT201)
N ⁸ - (fluoromethyl) - thymidine ^{(N 8 - (fluoromethyl) -thymidine} ) (21: NFT201)
NFT201 (21) was synthesized from commercially available thymidine 11 in one step according to the method of KK Ogilive et al. (Nucleic Acids Research, 6, 1695 (1979)).

¹ H NMR (CD ₃ OD, 500 MHz) δ7.89 (s, 1H), 6.28 (t, J = 6.5 Hz, 1H), 5.97 (d, J = 50.5 Hz, 2H), 4.40 (quint, J = 3.0 Hz, 1H), 3.92 (q, J = 3.0Hz, 1H), 3.80 (dd, J = 12.5 and 3.0Hz, 1H), 3.73 (dd, J = 12.5 and 3.5Hz, 1H), 2.28 (ddd, J = 13.5, 6.5 and 3.5Hz, 1H), 2.22 (dd, J = 13.5 and 3.5Hz, 1H), 1.91 (s, 3H).

Example 16 (FT202)
5- (2-Fluoroethyl) -2′-deoxyuridine (22: FT202)
According to the method of JD Fissekis et al. And the method of H. Griengl et al. (J. Org. Chem., 29, 2670 (1964): J. Med. Chem., 30, 1199 (1987)), commercially available γ-butyrolactone (γ FT202 was synthesized in 9 steps from -Butyrolactone).

¹ H NMR (CD ₃ OD, 500 MHz) δ7.92 (s, 1H), 6.26 (t, J = 6.5 Hz, 1H), 4.53 (dtd, J = 47.0, 5.5 and 3.0 Hz, 2H), 4.37 ( quint, J = 3.0 Hz, 1H), 3.92 (q, J = 3.0Hz, 1H), 3.80 (dd, J = 12.0 and 3.0Hz, 1H), 3.73 (dd, J = 12.0 and 3.5Hz, 1H), 2.71 (td, J = 5.5 and 2.0Hz, 1H), 2.68 (td, J = 5.5 and 1.5Hz, 1H), 2.26 (m, 1H), 2.21 (m, 1H).

Example 17 (FTS202)
1- (2-Deoxy-4-thio-erythro-pentofuranosyl) -5- (2-fluoroethyl) -uracil (1- (2-Deoxy-4-thio-erythro-pentofuranosyl) -5- (2- fluorethyl) -uracil) (23: FTS202)
According to the method of SGRahim et al. And the method of JASecrist et al. (J. Med. Chem., 39, 789 (1996): J. Med. Chem., 34, 2361 (1991)), commercially available D-erythro-pentofuranoside ( FTS202 (23) was synthesized from D-erythro-pentofuranoside) in 12 steps.

¹ H NMR (DMSO-d ₆ , 400 MHz) δ 11.4 (s, 1H), 7.91 (s, 1H), 6.27 (t, J = 7.4 Hz, 1H), 5.26 (d, J = 3.8 Hz, 1H), 5.18 (t, J = 5.4 Hz, 1H), 4.50 (dt, J = 40.0 and 6.4 Hz, 2H), 4.37 (quint, J = 3.5 Hz, 1H), 3.60 (m, 2H ), 3.29 (m, 1H), 2.68 (td, J = 6.2 and 3.3Hz, 1H), 2.62 (td, J = 6.0 and 3.7Hz, 1H), 2.18 (d, J = 4.0 Hz, 1H), 2.16 (d, J = 3.8 Hz, 1H).

Example 18
Synthesis of 2-[ < ¹⁴ > C] -NFT202 It was synthesized according to the method of WF Edgell et al. (J. Am. Chem. Soc., 77, 4899 (1955)) under an argon stream as in Example 1. Fluorotosyloxyethane (6.8 mg, 33.8 μmol), K ₂ CO ₃ (9.3 mg, 67.6 μmol), 2- [ ¹⁴ C] -thymidine (37 MBq, 16.9 μmol). The reaction was allowed to proceed overnight at 50 ° C. in 5 mL of Acetone / DMF solvent. The reaction solution was diluted with 10 mL of ether, unreacted fluorotosyloxyethane was adsorbed through a SepPak Silica cartridge column, and the target product was eluted with 10 mL of CHCl ₃ / MeOH = 5/1. After evaporating the solvent of the eluted fraction, purification was performed with TLC (Silicagel 60). 2-[< ¹⁴ > C] -NFT202 was obtained (35.2 MBq, 95%).

Example 19
Examination of in vitro phosphorylation ability of fluorothymidine derivatives The phosphorylation activity of fluorothymidine derivatives against recombinant human thymidine kinase 1 (rTK ₁ ) was measured. rTK ₁ was prepared according to the method of Lunato AG et al. (J. Med. Chem. 42, pages 3378-3389 (1999)). The phosphorylation activity was determined by separating and quantifying radioactive phosphorylated mononucleoside obtained by phosphoryl transfer reaction of γ- ³³ P-ATP by thin phase chromatography. That is, 1 mM γ- ³³ P-ATP and substrate 100 μM were added to a reaction solution (50 mM Tris-HCl (pH 7.6), 5 mM MgCl ₂ , 15 mM NaF, 125 mM KCl, 10 mM DTT and 0.5% BSA), and 615 ng The reaction was started by adding / mL of rTK ₁ . The enzyme reaction was carried out at 37 ° C. for 15 minutes, and then the reaction was stopped by heat treatment at 100 ° C. for 3 minutes. The reaction solution after stopping the reaction was centrifuged, and the supernatant was collected and added to PEI-cellulose plate (Merack) in 2 μL units. The thin phase plate was developed with isobutyric acid / ammonium hydroxide / water = 66/1/33 for 12 hours, and the ratio of radioactive peak components was analyzed with BAS-1500.

Table 4 shows the phosphorylation activity of fluorothymidine derivatives against recombinant human thymidine kinase 1 (rTK ₁ ). The phosphorylation activity was shown as relative activity when the natural substrate, thymidine, was taken as 100. The phosphorylating ability was in the order of thymidine>NFT202> NFT201 = NFTS202> FTS202 = NFT203 = FT202> NFAU202.

Example 20
Examination of nucleoside transporter transport activity of fluorothymidine derivatives The affinity of fluorothymidine derivatives for nucleoside transporters was measured. As materials, erythrocytes of ICR mice (female, 7-8 weeks old, body weight 30 g) were used. Anesthesia was given by intraperitoneal administration of ketamine (100 mg / kg) + xylazine (10 mg / kg), and venous blood was collected in a 3.2% trisodium citrate aqueous solution by cardiac blood sampling. The collected blood was centrifuged at 3,000 rpm × 10 minutes at 4 ° C. to remove plasma and leukocyte layer. Thereafter, erythrocytes were obtained by washing 4 times with a buffer (140 mM NaCl, 1.4 mM MgSO ₄ , 18 mM Tris-HCl pH 7.4). The affinity of the fluorothymidine derivative for the nucleic acid transport carrier was determined with reference to the method of Gati WP et al. (Biochem Pharmacol. 33, 3325-3331 (1984); Molecular Pharmacol. 23, 146-152 (1982)). . That is, erythrocytes were diluted with a buffer solution so that the hematocrit value was 11%. A 0.05-0.50 mM (0.05, 0.1, 0.25, 0.50) thymidine solution containing 2- [ ¹⁴ C] -thymidine (37 KBq / mL), and A total of 16 assay solutions containing 0.0-2.0 mM (0, 0.5, 1.0, 2.0) of fluorothymidine derivatives were prepared. Each 0.2 mL of assay solution was added to 0.2 mL of red blood cell solution previously placed in a 1.5 mL tube and allowed to ingest for 3 seconds. Subsequently, the uptake of 2- [ ¹⁴ C] -thymidine was stopped by adding 0.4 mL of 0.02 mM nitrobenzylthioinosin (NBMPR) solution, which is a selective inhibitor of nucleoside transporter. I let you. The sample was quickly centrifuged at 12,800 g for 1 minute, washed again with 1.0 mL of NBMPR solution, and 2- [ ¹⁴ C] -thymidine was extracted with 0.5 mL of 5% perchloric acid solution. . The tube after perchloric acid treatment was centrifuged again, 0.15 mL of the supernatant was collected, 10 mL of liquid scintillator (ACS-II; Amersham Bioscience) was added, and the radioactivity was measured with a liquid scintillation counter (LSC-5000; Aloka). Measured with The measurement was carried out twice for each sample, the average value was determined, and the initial velocity: V (pmoles thymidine / μg packed erythrocyte / sec) was determined. The Ki value of the fluorothymidine derivative is calculated by changing the slope of the plot (Kmap / Vmax) obtained from Lineweaver-Burk plot (1 / v to 1 / s plot) to the concentration of each fluorothymidine derivative (interpreted as an inhibitor). It was calculated | required by the secondary plot (replot, Kmapp / Vmax-i) plotted against (Masashi Onishi, Introductory enzyme kinetics experiment: Academic Publishing Center).

The results are shown in Table 5. The Km value of thymidine was 0.26 ± 0.09 mM. The affinity for the nucleoside transporter was in the order of NFTS202> FTS202> Thymidine> NFT201> NFT203 = NFAU202> FT202 = NFT202.

Example 21
Study on in vitro metabolic degradation sensitivity of fluorothymidine derivatives The sensitivity of fluorothymidine derivatives to thymidine phosphorylase was evaluated. The reaction was started by adding 0.015 unit enzyme solution (from E. coli, Sigma) to 0.1 M potassium phosphate buffer (pH 7.4) containing 20 nmol substrate. The enzymatic reaction was carried out at 25 ° C for 60 minutes and then stopped by adding 2 N aqueous perchloric acid. The reaction solution after stopping the reaction was centrifuged, and a certain amount of aqueous potassium hydroxide solution was added to the recovered supernatant to neutralize it. The neutralized sample was centrifuged and the supernatant was collected. The concentration of the parent compound in the collected supernatant was quantified by high-performance liquid chromatography using an absolute calibration curve method (column: Mightysil RP-18 GP Aqua (Kanto Chemical), mobile phase: methanol / water / TFA mixture) ).

Table 6 shows the metabolic stability of fluorothymidine derivatives to thymidine phosphorylase. The relative value of the parent compound concentration at 60 minutes was shown with the parent compound concentration at 0 minutes as 100%. Metabolic degradation was observed only in the positive controls Thymidine and FT202.

Example 22
Respect thymidine kinase 1 dependent ^2- [14 C] -NFT202 cellular uptake 2- ^[14 C] thymidine kinase 1 -NFT202 dependent uptake into cells, the thymidine kinase-deficient cell line L-M (TK-) And the uptake with the LM cell which is the parent strain was compared. 2.0 × 10 ⁵ LM and LM (TK−) cells in logarithmic growth phase were seeded in a 24-well plate and cultured overnight, then 2- [ ¹⁴ C] -NFT202 1.85 KBq (0.8 nmol) In addition, the cells were taken up for 1 hour. The cells were washed three times with ice-cold phosphate buffer, and the cells were lysed with 0.5 mL of 0.2N NaOH, and then 10 mL of liquid scintillator (ACS-II; Amersham Bioscience) was added to reduce the radioactivity incorporated into the cells. It measured with the liquid scintillation counter (LSC-5000; Aloka). As a result, 2- [ ¹⁴ C] -NFT202 was transferred to LM cells at 24.70 ± 1.71 (pmol / 10 ⁶ cells / h) and LM (TK−) cells at 3.06 ± 1.22. Compared with (pmol / 10 ⁶ cells / h), the accumulation was 8 times higher (Student's t-test; p <0.000005).

Example 23
2- Correlation between [ ¹⁴ C] -NFT202 cellular uptake and proliferation degree In order to clarify whether the cell accumulation of 2- [ ¹⁴ C] -NFT202 reflects the difference in proliferation degree, The change in the ratio of 2- [ ¹⁴ C] -NFT202 incorporation into different A549 human lung cancer cell lines and the proportion of the S phase fraction, which is a cell proliferation marker, was compared. The 2- [ ¹⁴ C] -NFT202 uptake assay method into A549 cells was performed in the same manner as in Example 22. For measurement of the S-phase fraction, the A549 cell line cultured as in the uptake experiment was collected by trypsin treatment and collected in a 15 mL centrifuge tube. Cells were sedimented by centrifugation and samples for DNA analysis were prepared using the CycleTest ^™ PLUS DNA Reagent Kit (Beckton Dickinson) according to the protocol attached to the Kit. The DNA content per cell of the sample is represented by a histogram by flow cytometry (FACS Caliber; Beckton Dickinson), and the proportion of the S-phase fraction (% S-Phase) is calculated using Mod-Fit LT software (Beckton Dickinson) did.

The results are shown in FIG. Incorporation of 2- [ ¹⁴ C] -NFT202 into A549 cells correlated well with the S-phase fraction (% S-Phase) of cell proliferation marker (r ² = 0.92).

Example 24
Biodistribution using normal mice of [ ¹⁸ F] NFT202 A 4-week-old ddY mouse (average body weight 28.9 g, 4 mice in each group) was subjected to labonal anesthesia, and [ ¹⁸ F] NFT202 was about 1.48 MBq per mouse. It was administered intravenously. After each time, the mice were sacrificed by cardiac blood sampling, and the organ weight and radioactivity were measured with a single channel analyzer. Incorporation of radioactivity into the tissue was calculated as a percentage of the dose per tissue g with respect to time (Table 7). As a result, the uptake of radioactivity in the small intestine, which is a proliferating tissue, was clearly higher than that of brain and muscle, which are non-proliferating tissues. Radioactivity accumulation in the lower limb bones (including the bone marrow of the proliferating tissue) was also observed.

Example 25
Biodistribution of [ ¹⁸ F] NFT202 using tumor-transplanted mice Biodistribution was performed in the same manner as in Example 24 in C57BL / 6 mice subcutaneously transplanted with a Lewis lung cancer cell line. As a result (Table 8), the uptake of radioactivity in the small intestine, a proliferating tissue, was clearly higher than that of muscle, a non-proliferating tissue. Radioactivity accumulation in the lower limb bones (including the bone marrow of the proliferating tissue) was also observed. The uptake of radioactivity in the tumor was higher than the non-proliferating tissue muscle.

Example 26
^[18 F] Biodistribution <br/> Lewis lung carcinoma cell lines using tumor implantation mice NFT203 was prepared as in Example 24 Biodistribution in C57BL / 6 mice were implanted subcutaneously. As a result (Table 9), the uptake of radioactivity in the small intestine, a proliferating tissue, was clearly higher than that of muscle, a non-proliferating tissue. Radioactivity accumulation in the lower limb bones (including the bone marrow of the proliferating tissue) was also observed. The uptake of radioactivity in the tumor was higher than the non-proliferating tissue muscle.

Example 27
Biodistribution of [ ¹⁸ F] NFT401 using tumor-transplanted mice Biodistribution in C57BL / 6 mice subcutaneously transplanted with a Lewis lung cancer cell line was carried out in the same manner as in Example 24. As a result (Table 10), the uptake of radioactivity in the small intestine, a proliferating tissue, was clearly higher than that of muscle, a non-proliferating tissue. Radioactivity accumulation in the lower limb bones (including the bone marrow of the proliferating tissue) was also observed. The uptake of radioactivity in the tumor was higher than non-proliferating tissue muscle 30 minutes after administration.

Example 28
In ^[18 F] NFT202 in vivo metabolism ^[18 F] order to confirm the in vivo stability of NFT202, it was analyzed for mouse plasma and urine metabolites. Five radiochemical components were identified in the plasma TLC radiochromatogram of mice after [ ¹⁸ F] NFT202 administration (FIG. 3). The radiochemical component ratio (%) is shown in Table 11. At 30 minutes, 74.8, 80.1% of plasma radioactivity was unchanged [ ¹⁸ F] NFT202. At 2 hours, all 5 components were detected, and more than 40% of plasma radioactivity was unchanged, and the origin component (A) was observed at a similar rate.

The results of TLC radiochromatogram analysis of urine are shown in FIG. At 30 minutes, 98% of the radiochemical component was unchanged. On the other hand, at 2 hours, 81.4% and 58.8% of the urinary radioactivity were unchanged, and most of the remaining was the origin component (A). From the above results, it was confirmed that [ ¹⁸ F] NFT202 is relatively stable in vivo.

The radiofluorine-labeled nucleoside derivative of the present invention is stable in vivo and passes through a nucleoside transporter, and is then phosphorylated by thymidine kinase 1 to stay in the cell, or is incorporated into DNA and synthesized into DNA. Since the activity is reflected, it is useful for diagnostic imaging of cell proliferation.

It is reaction formula which shows the scheme which manufactures the radioactive fluorine labeled compound of this invention. It is a graph which shows the correlation with the cellular uptake | capture of 2-[< ¹⁴ > C] -NFT202, and the proliferation degree. It is a plasma TLC radiochromatogram of a mouse | mouth after [ ¹⁸ F] NFT202 administration. It is a TLC radiochromatogram of mouse urine after administration of [ ¹⁸ F] NFT202.

Claims (14)

An agent for diagnosing tissue proliferative ability, comprising an ¹⁸ F-labeled compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.

(In the formula (I), R ₁ is a methyl group or an ¹⁸ F-labeled fluoroalkyl substituent having 1 to 2 carbon atoms, R ₂ is hydrogen or an ¹⁸ F-labeled fluoroalkyl substituent having 1 to 6 carbon atoms, R ₃ Is oxygen or sulfur, R ₄ is hydrogen or fluorine, provided that both R ₁ and R ₂ are ¹⁸ F-labeled fluoroalkyl substituents, and R ₁ is a methyl group and R ₂ is hydrogen except for.) The drug according to claim 1, wherein R ₁ is a methyl group. R ₂ is ^{18 F-labeled} fluoroethyl group, ^{18 F-labeled} fluoropropyl group, and ^{18 F-labeled} fluoropentyl agent according to claim 2 is a fluoroalkyl substituent selected from the group consisting of groups. The drug according to claim 3, wherein R ₃ is oxygen and R ₄ is hydrogen. The drug according to claim 4, wherein R ₂ is an ¹⁸ F-labeled fluoroethyl group. A nucleoside derivative represented by the following formula (II).

(In the formula (II), R ₁ is an alkyl substituent having 1 to 2 carbon atoms having a methyl group or a leaving group, R ₂ is an alkyl substituent having 1 to 6 carbon atoms having hydrogen or a leaving group, R ₃ is oxygen or sulfur, R ₄ is hydrogen or fluorine, R ₅ is a protecting group, provided that both R ₁ and R ₂ are alkyl substituents having 1 to 6 carbon atoms having a leaving group. And R ₁ is a methyl group and R ₂ is hydrogen.) The derivative according to claim 6, wherein R ₁ and R ₂ are each independently an alkyl substituent having a leaving group selected from the group consisting of a tosyl group, a mesyl group and a triflate group. The derivative according to claim 7, wherein R ₅ is a protecting group selected from the group consisting of a toluyl group, a 4 ', 4'-dimethoxytrityl group, a trityl group and a benzyl group. The derivative according to claim 8, wherein R ₁ is a methyl group. The derivative according to claim 9, wherein R ₂ is an alkyl substituent selected from the group consisting of an ethyl group having a leaving group, a propyl group having a leaving group, and a pentyl group having a leaving group. The derivative according to claim 10, wherein R ₃ is oxygen and R ₄ is hydrogen. The derivative according to claim 11, wherein R ₂ is an ethyl group having a leaving group. The derivative according to claim 12, wherein the leaving group is a tosyl group. The derivative according to claim 13, wherein the protecting group is a toluyl group.

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