JPH10298194A - 2-deoxy-3-ethynyl-beta-d-ribofuranosyl derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject new nucleic acid derivative consisting of a specific 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative, exhibiting extremely strong cytocidal activity and excellent antitumor activity and useful as an antitumor agent, etc. SOLUTION: This derivative is a new 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative expressed by the formula I (B is a nucleic acid base which may have substituent) and its ester easily decomposable in vivo or its pharmacologically permissible salt. The derivative has excellent antitumor activity and is useful as an antitumor agent, etc. The compound can be produced by reacting a compound of the formula II (R1 and R2 are each a trialkylsilyl) with an acylating agent in a solvent in the presence of a basic catalyst, desilylating the obtained acylated product, reacting the resultant compound of the formula III (Acyl is an acyl) with a tributyltin halide in the presence of azoisobutyronitrile to eliminate the 2-OH group and deacylating the product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel nucleic acid derivative. The compounds of the present invention have, for example, excellent antitumor activity and are useful as antitumor agents.

[0002]

2. Description of the Related Art Hitherto, pyrimidine compounds such as 5-fluorouracil, tegafur, UFT, doxyfluridine, carmofur, cytarabine, and enocitabine have been known as antitumor agents which are nucleic acid antimetabolites. Examples of the nucleoside having an alkynyl group at the 3-position of pentofuranose include Chem. Pharm. Bu
ll 35 (6) 2605-2608 (1987)
[2,5-di- (tert-butyldimethylsilyl)-
3-C-phenethynyl-β-D-ribo-pentofuranosyl] uracil and 1- [2,5-di- (tert-butyldimethylsilyl) -3-C-phenethynyl-β-D
-Ribo-pentofuranosyl] adenine was produced by Tetrahedron
Letters, 36 (7) 1031-1034, 1995
1- [2-O- (tert-butyldimethylsilyl)
-3-C-Ethynyl-β-D-ribo-pentofuranosyl) thymine is described in Tetrahedron, 47 (9) 1727-1.
736 (1991) describes 1- [2-O- (tert-butyldimethylsilyl) -3-C-ethynyl-β-D-ribo-pentofuranosyl) thymine, respectively, but its pharmacological action is described. It has not been. Also, 3-
The ethynyl-β-D-ribofuranosyl derivative is described in Patent Application No. WO 96/18636, which was previously filed by the present inventors, but is 2-deoxy-3-ethynyl-β-
D-ribofuranosyl derivatives are not yet known.

[0003]

An object of the present invention is to provide a novel 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative which has excellent antitumor activity and is useful as an antitumor agent. is there.

[0004]

According to the present invention, there is provided a compound represented by the general formula (1):
A 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative represented by the formula: and an easily eliminable ester or a pharmaceutically acceptable salt thereof in a living body.

[0005]

Embedded image (In the formula, B represents a nucleobase that may have a substituent.)

As a result of intensive studies, the present inventors have found that a nucleic acid derivative having an ethynyl group introduced at the 3-position of 2-deoxypentofuranose exhibits excellent antitumor activity and is useful as an antitumor agent. Heading, the present invention has been completed.

In the above general formula (1), examples of the nucleic acid base represented by B include pyrimidine bases such as cytosine, uracil and thymine, and purine bases such as adenine and guanine. Examples of the substituent include a halogen atom,
Examples include acyl groups such as lower alkyl groups, aliphatic acyl groups and aromatic acyl groups, and substituted oxycarbonyl groups such as lower alkoxycarbonyl groups, lower alkenyloxycarbonyl groups and aralkyloxycarbonyl groups. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. As the lower alkyl group, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, ter
Examples thereof include linear or branched alkyl groups having 1 to 6 carbon atoms such as t-butyl, pentyl, and hexyl groups. Examples of the aliphatic acyl group include linear or branched acyl groups having 1 to 6 carbon atoms such as formyl, acetyl, propionyl, butyryl, isobutyryl, pentanoyl, and hexanoyl groups, and aromatic acyl groups include benzoyl , Α-naphthoyl and β-naphthoyl groups. Further, these may have a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, or the like as a substituent. Examples of the lower alkyl group and the halogen atom include the same as those described above. Examples of the lower alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n
-Butoxy, isobutoxy, sec-butoxy, ter
Examples thereof include linear or branched alkoxy groups having 1 to 6 carbon atoms such as t-butoxy, pentyloxy, and hexyloxy groups.

The lower alkoxycarbonyl group includes, for example, methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-
Butoxycarbonyl, isobutoxycarbonyl, sec
Linear or branched alkoxycarbonyl groups having 2 to 7 carbon atoms, such as -butoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, and hexyloxycarbonyl groups. Examples of the lower alkenyloxycarbonyl group include vinyloxycarbonyl,
Examples thereof include a linear or branched alkenyloxycarbonyl group having 3 to 7 carbon atoms such as allyloxycarbonyl, isopropenyloxycarbonyl, 1-butenyloxycarbonyl, and 2-butenyloxycarbonyl group. Examples of the aralkyloxycarbonyl group and the like include aralkyloxycarbonyl groups having 8 to 12 carbon atoms such as benzyloxycarbonyl, phenethyloxycarbonyl, α-naphthylmethyloxycarbonyl, and β-naphthylmethyloxycarbonyl, and these are substituted. The group may have a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, or the like.

[0009] Ester-forming residues which can be easily eliminated in vivo are defined as those which form an ester with the hydroxyl groups at positions 3 and 5 of the compound represented by the general formula (1) and which are present in blood and tissues of mammals including humans. Means a non-toxic ester group which is easily cleaved to release the compound represented by the general formula (1), and any ester group which protects a hydroxyl group of a well-known nucleoside to form an ester. For example, an acyl group such as an aliphatic acyl group which may have a substituent or an aromatic acyl group which may have a substituent, an aryloxycarbonyl group, a lower alkoxycarbonyl group, a lower alkylcarbamoyl group, and an amino acid And the like. Examples of the aliphatic or aromatic acyl group which may have a substituent include a lower alkanoyl group, an arylcarbonyl group, a heterocyclic carbonyl group, an acyloxyacyl group, and the like. As the lower alkanoyl group, for example, formyl, acetyl, propionyl, butyryl, isobutyryl, pentanoyl, hexanoyl, chloroacetyl, dichloroacetyl, trichloroacetyl, trifluoroacetyl, methoxyacetyl, methoxyacetyl, ethoxyacetyl group as a substituent such as a halogen atom, lower alkoxy Examples thereof include an alkanoyl group having 1 to 6 carbon atoms which may have a group or the like.

Examples of the arylcarbonyl group include benzoyl, α-naphthylcarbonyl, β-naphthylcarbonyl, 2-methylbenzoyl, 3-methylbenzoyl, 4-methylbenzoyl, 2,4-dimethylbenzoyl, 4-ethylbenzoyl, -Methoxybenzoyl,
3-methoxybenzoyl, 4-methoxybenzoyl,
2,4-dimethoxybenzoyl, 4-ethoxybenzoyl, 2-methoxy-4-ethoxybenzoyl, 4-propoxybenzoyl, 2-chlorobenzoyl, 3-chlorobenzoyl, 4-chlorobenzoyl, 2,3-dichlorobenzoyl, 2- Bromobenzoyl, 4-fluorobenzoyl, 2-carboxybenzoyl, 3-carboxybenzoyl, 4-carboxybenzoyl, 2-cyanobenzoyl, 4-cyanobenzoyl, 2-nitrobenzoyl, 4-nitrobenzoyl, 2,4-dinitrobenzoyl group And the like. Examples of the substituents include benzoyl and naphthylcarbonyl groups which may have a lower alkyl group, a lower alkoxy group, a halogen atom, a carboxyl group, a cyano group, a nitro group and the like.

Examples of the heterocyclic carbonyl group include 2
-Furanylcarbonyl, 4-thiazolylcarbonyl, 2
-Quinolylcarbonyl, 2-pyrazinylcarbonyl, 2
-Pyridylcarbonyl, 3-pyridylcarbonyl, 4-
And a pyridylcarbonyl group. Examples of the acyloxyacyl group include acetyloxyacetyl, propionyloxyacetyl, α- (acetyloxy) propionyl, β- (propionyloxy) propionyl, and the like. Examples of the aryloxycarbonyl group include phenoxycarbonyl, α-naphthyloxycarbonyl, β-naphthyloxycarbonyl, 2-methylphenoxycarbonyl, 3-methylphenoxycarbonyl, 4-methylphenoxycarbonyl, 2,4-dimethylphenoxycarbonyl, -Ethylphenoxycarbonyl, 2-methoxyphenoxycarbonyl, 3-methoxyphenoxycarbonyl, 4-methoxyphenoxycarbonyl, 2,4-dimethoxyphenoxycarbonyl,
4-ethoxyphenoxycarbonyl, 2-methoxy-4
-Ethoxyphenoxycarbonyl, 2-chlorophenoxycarbonyl, 3-chlorophenoxycarbonyl, 4-
Chlorophenoxycarbonyl, 2,3-dichlorophenoxycarbonyl, 2-bromophenoxycarbonyl, 4
-Fluorophenoxycarbonyl, β-methyl-α-naphthyloxycarbonyl, β-chloro-α-naphthyloxycarbonyl and the like.

The lower alkoxycarbonyl group includes, for example, methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-
Butoxycarbonyl, isobutoxycarbonyl, sec
Linear or branched alkoxycarbonyl groups having 2 to 7 carbon atoms, such as -butoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, and hexyloxycarbonyl groups. Examples of the lower alkylcarbamoyl group include linear or branched alkyl groups having 1 to 6 carbon atoms such as methylcarbamoyl, ethylcarbamoyl, propylcarbamoyl, butylcarbamoyl, pentylcarbamoyl, hexylcarbamoyl, dimethylcarbamoyl, and diethylcarbamoyl. And a carbamoyl group mono- or di-substituted. The amino acid residue represents a group formed by removing a hydroxyl group from a carboxyl group of an amino acid, and the amino acid includes, for example, glycine, alanine, β-alanine, valine, isoleucine and the like. Any amino acid residue described in 104093 may be used.

Other ester groups include, for example, THE
ODORA W. GREENE, "PROTECTIV
E GROUPS IN ORGANIC SYNTH
ESIS Second Edition ”, JOHN WILE
Y & SONS, INC. (1991), edited by The Chemical Society of Japan <New Experimental Chemistry Course 4> “Synthesis and Reaction of Organic Compounds (V)”, Chapter 11, p. 2495 Maruzen (1983), JP-A-61-106593, JP-A-62-149696.
And any of the conventional ester groups described in JP-A-1-153696. B is preferably cytosine, uracil, thymine, adenine, guanine, 5-fluorocytosine, 5-fluorouracil, 5-bromocytosine, 5-bromouracil,
-N-methylcytosine or 4-N, N-dimethylcytosine, and more preferably, cytosine, uracil, thymine, and adenine. The ester-forming residue which can be easily eliminated in the living body preferably includes an acyl group, and more preferably includes an acetyl group and a benzoyl group.

The compound of the present invention also includes a salt form. The salt is not particularly limited as long as it is a pharmaceutically acceptable salt, and examples thereof include hydrochloride, hydrobromide and sulfate. Examples thereof include inorganic acid salts, organic sulfonic acid salts such as methanesulfonic acid salt and benzenesulfonic acid salt, and acid addition salts such as organic acid salt such as aliphatic carboxylic acid salt such as acetate, propionate and trifluoroacetate. Is done. The compounds of the present invention also include hydrates thereof. The compound of the present invention represented by the general formula (1) can be produced, for example, according to the following reaction scheme.

[0015]

Embedded image (Wherein B is the same as above, R ₁ and R ₂ represent a trialkylsilyl group, and Acyl represents a protected acyl group)

(Step A) The compound represented by the general formula (3) is reacted with an acylating agent in a solvent in the presence or absence of a basic catalyst in a solvent. Get. The compound represented by the general formula (2) is
rahedron Letters, 36 (7) 1031-1034
It is a known compound synthesized by the method described in 1995, or is synthesized according to a known method, and specifically, is produced by the method described in Reference Examples below.
As the trialkylsilyl group represented by R ₁ and R ₂ , a trialkylsilyl group substituted by a lower alkyl group having 1 to 6 carbon atoms such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, triisopropylsilyl and the like is used. Is done. As the acylating agent, acetic acid, propionic acid, lower aliphatic carboxylic acids having 2 to 6 carbon atoms such as butyric acid,
Aromatic carboxylic acids such as benzoic acid and p-nitrobenzoic acid;
Known and commonly used compounds such as acid halides and acid anhydrides thereof can be used. The solvent is not particularly limited as long as it does not affect the reaction, and examples thereof include acetonitrile, tetrahydrofuran, nitromethane, and methylene chloride. Examples of the basic catalyst include p-dimethylaminopyridine (DMAP). As for the reaction ratio, the acylating agent is used in an amount of 3 to 10 times, preferably 1 to 5 times the amount of the compound of the formula (2). The reaction temperature is 0 to 150 ° C., preferably room temperature to 100 ° C., and the reaction time is 0.1 to 100 hours to complete the reaction.

(Step B) The compound represented by the general formula (4) is obtained by reacting the compound represented by the general formula (3) with an acid in a solvent to obtain a compound represented by the general formula (4). The solvent is not particularly limited as long as it does not affect the reaction, and examples thereof include acetonitrile and tetrahydrofuran. As the acid, hydrochloric acid, sulfuric acid, acetic acid and the like can be used.
The reaction rate is such that the acid is 2-1 to the compound of the general formula (3).
It is preferable to use a 0-fold molar amount. The reaction temperature is 0 to 80 ° C,
Preferably it is about room temperature, and the reaction time is 5 to 24 hours.

(Step C) The compound represented by the general formula (4) is reacted with 1,1'-thiocarbonyldiimidazole in a solvent, and then the target intermediate is isolated or isolated without isolation. The presence of azoisobutyronitrile (AIBN) and the reaction with a trialkyltin hydride such as tributyltin hydride eliminates the hydroxyl group at the 2-position to obtain a compound represented by the general formula (5). The solvent is not particularly limited as long as it does not affect the reaction, and examples thereof include acetonitrile, tetrahydrofuran, methylene chloride, and benzene.
The reaction rate is 1.5 to 10 times, preferably 2 to 4 times the molar amount of 1,1'-thiocarbonyldiimidazole and AIBN is 0.1 to 0.5 times the amount of the compound of the formula (4). It is preferred to use a 2-fold molar amount of trialkyltin hydride in a 4- to 10-fold molar amount. The reaction temperature is from 0 ° C. to the boiling point of the solvent, and the reaction time is 3 to 12 hours, and the reaction proceeds advantageously.

(Step D) The compound represented by the general formula (1) is obtained by reacting the compound represented by the general formula (5) with a base in a solvent to obtain a compound represented by the general formula (1). The solvent is not particularly limited as long as it does not affect the reaction, but examples thereof include methanol and ethanol. Examples of the base include sodium hydroxide, potassium hydroxide, sodium methylate and the like. The reaction ratio is 0.1 to 10 times the molar amount of the base with respect to the compound of the general formula (5),
Preferably, it is used in a molar amount of 0.5 to 1 times. The reaction temperature is 0 to 100 ° C, preferably room temperature to 70 ° C,
The reaction is completed in 2 to 5 hours. The compound of the present invention obtained by the above method is generally known separation and purification means,
For example, it can be isolated and purified by using concentration, solvent extraction, filtration, recrystallization, various types of chromatography and the like.

The compound of the present invention can be made into a pharmaceutical composition containing the compound as an active ingredient or a suitable pharmaceutical carrier according to a conventional method. As the carrier used here, various ones commonly used in ordinary drugs, for example, excipients, binders, disintegrants, lubricants, coloring agents, flavoring agents, odorants, surfactants and the like are used. be able to. When the medicament or the pharmaceutical composition of the present invention is used as a therapeutic agent for treating tumors in mammals including humans, the dosage unit form is not particularly limited and can be appropriately selected depending on the purpose of the treatment. Specifically, injections and suppositories , External preparations (ointments, patches, etc.), parenteral preparations such as aerosol preparations, tablets, coated tablets, powders, granules, capsules, pills, and liquid preparations (suspension preparations, emulsions, etc.). Can be

The above-mentioned various compositions are formulated by a formulation method generally known in the art. When molded into an injection, the carrier may be, for example, diluents such as water, ethyl alcohol, macrogol, propylene glycol, ethoxylated isostearyl alcohol, polyoxylated isostearyl alcohol, polyoxyethylene sorbitan fatty acid esters, and citric acid. PH adjusters and buffers such as sodium acid, sodium acetate, sodium phosphate, etc.
Stabilizers such as sodium pyrosulfite, ethylenediaminetetraacetic acid, thioglycolic acid, and thiolactic acid can be used.
In this case, a sufficient amount of salt, glucose or glycerin to prepare an isotonic solution may be included in the pharmaceutical preparation, and a usual solubilizing agent, soothing agent, local anesthetic, etc. may be added. May be. By adding these carriers, injections for subcutaneous, intramuscular, and intravenous injections can be produced by a conventional method.

In molding into a suppository form, carriers such as polyethylene glycol, cacao butter, lanolin, higher alcohols, esters of higher alcohols, gelatin, semi-synthetic glyceride, and Witepsol (registered trademark: Dynamite Nobel) And the like, to which an appropriate absorption promoter can be added. In preparing ointments, for example, in the form of pastes, creams and gels, commonly used bases, stabilizers, wetting agents, preservatives and the like are blended as necessary, and mixed and formulated according to ordinary methods. You. As a base, for example, white petrolatum, paraffin, glycerin, a cellulose derivative, polyethylene glycol, silicon, bentonite and the like can be used. As the preservative, methyl paraoxybenzoate, ethyl paraoxybenzoate, propyl paraoxybenzoate and the like can be used. When a patch is produced, the above-mentioned ointment, cream, paste, gel or the like may be applied to a usual support in a conventional manner. As a support,
A woven fabric, a nonwoven fabric, a film of a soft vinyl chloride, a polyethylene, a polyurethane, or the like made of cotton, a staple, or a chemical fiber, or a foam sheet is suitable.

In the preparation of oral solid preparations such as tablets, powders and granules, carriers such as lactose, sucrose, sodium chloride, glucose, urea, starch, calcium carbonate, kaolin, crystalline cellulose, silicic acid, Excipients such as methylcellulose, glycerin, sodium alginate, gum arabic, simple syrup, dextrose solution, starch solution, gelatin solution, polyvinyl alcohol, polyvinyl ether, polyvinylpyrrolidone, carboxymethylcellulose, shellac, methylcellulose, ethylcellulose, water, ethanol, phosphorus Binders such as potassium acid, dry starch, sodium alginate, agar powder, laminaran powder, sodium hydrogen carbonate, calcium carbonate, polyoxyethylene sorbitan fatty acid esters,
Disintegrants such as sodium lauryl sulfate, stearic acid monoglyceride, starch, lactose, sucrose, stearic acid,
Cocoa butter, disintegrating inhibitors such as hydrogenated oils, quaternary ammonium salt group, absorption enhancers such as sodium lauryl sulfate, glycerin, humectants, such as starch, starch, lactose, kaolin, bentonite, etc. colloidal silicic acid Adsorbents, purified talc, stearate, boric acid powder, lubricants such as polyethylene glycol and the like can be used. Further tablets are tablets coated with ordinary skin as required, such as sugar-coated tablets,
Gelatin-coated tablets, enteric-coated tablets, film-coated tablets,
Double tablets, multilayer tablets and the like can be used.

Capsules are prepared by mixing with the various carriers exemplified above and filling into hard gelatin capsules, soft capsules and the like. When molded into pill form, for example, glucose, lactose, starch, cocoa butter,
Excipients such as hardened vegetable oil, kaolin and talc, gum arabic powder, tragacanth powder, binders such as gelatin and ethanol, and disintegrants such as laminaran and agar can be used.
Liquid preparations may be aqueous or oily suspensions, solutions, syrups and elixirs, which are prepared according to the usual methods using conventional additives. The amount of the compound of the present invention to be contained in the above-mentioned preparation varies depending on the dosage form, administration route, administration schedule and the like and cannot be stated unconditionally, and is appropriately selected from a wide range. It is good to be about.

The method of administration of the above preparation is not particularly limited, and may be, for example, enteral administration, oral administration, rectal administration, Oral administration, transdermal administration and the like are appropriately determined. For example, tablets, pills, solutions, suspensions, emulsions, granules and capsules are administered orally, and suppositories are administered rectally. In the case of an injection, it is administered intravenously, alone or as a mixture with a normal replenisher such as glucose or amino acid. Further, if necessary, it is administered alone, intraarterially, intramuscularly, intradermally, subcutaneously or intraperitoneally. The ointment is applied to skin, oral mucosa, and the like. The dose of the compound of the present invention is appropriately selected depending on the usage, age, sex, condition, type of tumor, type of the administered compound of the present invention, other conditions, etc. Approximately 1 to 1000 mg for an oral preparation and about 0.1 to 50 for an injection per unit dosage form.
0 mg and about 5-1000 mg for suppositories are desirable.
The daily dose of the drug having the above-mentioned administration form is usually about 0.1 to 200 mg / kg body weight / day, preferably about 0.5 to 100 mg / kg body weight / day. Good to do. These preparations of the present invention can be administered once or twice or four times a day.

The tumor which can be treated by administering the preparation containing the compound of the present invention is not particularly limited. For example, head and neck cancer, esophagus cancer, stomach cancer, colon cancer, rectal cancer, liver cancer, gallbladder / bile duct cancer. Pancreatic cancer, lung cancer, breast cancer, ovarian cancer, bladder cancer, prostate cancer, testicular tumor, bone / soft tissue sarcoma, malignant lymphoma, leukemia, cervical cancer, skin cancer, brain tumor and the like.

[0027]

The present invention will be described in more detail with reference to the following Reference Examples, Examples and Pharmacological Test Examples, but the present invention is not limited thereto.

Reference Example 1 1- (2-O-tert-butyldimethylsilyl-3-)
Production of C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil (1) 1- (2,5-O-di-tert-butyldimethylsilyl-β-D-ribo-pentofurano Syl) -5-methyluracil tert-butyldimethylsilyl chloride (hereinafter "T
BS Chloride ") (6.60g, 44.0mmo)
l), silver nitrate (7.50 g, 44.0 mmol) was dissolved in tetrahydrofuran (200 mL) and stirred for 5 minutes. There, thymidine (5.16 g, 20.0 mmol) and pyridine (8.10 g) were added.
(00 mL, 99.0 mmol), and the mixture was stirred at room temperature for 17 hours under an argon atmosphere. TBS chloride (660 mg, 4.40 mmol) and silver nitrate (1.50 g, 8.8) were added to the reaction solution.
0 mmol) and pyridine (1.60 mL, mmol).
Stirred for hours. The reaction mixture was filtered through celite, and ethanol (10 mL) was added to the filtrate, and the solvent was distilled off under reduced pressure. The residue was taken up in ethyl acetate (100 mL) and water (100 mL) 1N.
The organic layer was washed with water (100 mL) and saturated saline (100 mL × 2), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent. After azeotropic distillation with ethanol, the residue was subjected to silica gel column chromatography (φ7.5).
× 13 cm, 25% ethyl acetate / hexane) to give the title compound (6.90 g, 71%) as a colorless substance.

FAB-MS (LR): m / z 487 (M
H ⁺ , 100%). FAB-MS (HR): Calcd for C 22 H 43 N 2 O 6 Si
₂ : 487.2657. Found: 487.2650. ¹ H-NMR (CDCl ₃ ) δ; 8.26 (brs, 1H, N
_{H, D 2 O exchangeable),} 7.51 (s, 1H, H-
6), 6.02 (d, 1H , H-1, J 1 ', 2' = 5.6H
z), 4.20 (dd, 1H , H-2 ', J 2', 1 '= 5.6
Hz, J ₂ ′, 3 ′ = 5.3 Hz), 4.12 (m, 1H, H−
_{4 ', J 4', 5'a} = J 4 ', 5'b = 1.8Hz), 4.09
(M, 1H, H-3 ', J 3', 2 '= 5.3Hz, J 3', O
H = 3.5Hz), 3.95 (dd , 1H, H-5'a, J 5 '
a, 4 '= 1.8 Hz, J ₅ ' a, 5'b = 11.5 Hz),
3.81 (dd, 1H, H- 5'b, J 5 'b, 4' = 1.8H
z, J ₅ 'b, 5'a = 11.5 Hz), 2.72 (d, 1
H, 3′-OH, JOH, 3 ′ = 3.5 Hz, D ₂ O excha
ngeable), 1.93 (s, 3H, 5-Me), 0.95,
0.89 (each s, each 9H, t-Bu), 0.1
4,0.13,0.06,0.05 (each s, each 3
H, Me). Anal. _{Calcd for C 22 H 42 N 2} O 6 Si 2: C, 54.
29; H, 8.70; N, 5.76. Found: C, 54.
32; H, 8.66; N, 5.74.

(2) 1- (2,5-O-di-tert-)
Butyldimethylsilyl-3-oxo-β-D-ribo-pentofuranosyl) -5-methyluracil Molecular sieves 4A (2.00 g) heated in a microwave for 80 seconds was added to methylene chloride (10 mL) and chromium oxide ( (600 mg, 6.0 mmol) was quickly weighed and cooled with ice under an argon atmosphere. While stirring the mixture, pyridine (490 μL, 6.10 mmol) was added and 30
The mixture was stirred for minutes, acetic anhydride (570 μL, 6.0 mmol) was added, and the mixture was further stirred for 10 minutes. To this, 1- (2,5-di-O-te) dissolved in methylene chloride (4.0 mL) was added.
rt-butyldimethylsilyl-β-D-ribo-pentofuranosyl) -5-methyluracil (970 mg, 2.0 mmol)
l) was added dropwise over 5 minutes, and the mixture was stirred at 0 ° C for 30 minutes. The reaction mixture was added dropwise to ether (60 mL), stirred for 30 minutes, and suction-filtered with a funnel. The solvent was distilled off from the filtrate under reduced pressure, and the residue was subjected to ethyl acetate (20 mL) and water (20 mL).
And a 1N aqueous hydrochloric acid solution (5 mL).
The organic layer was washed with a saturated aqueous solution of sodium hydrogen carbonate (20 mL),
The extract was washed with water (20 mL × 2) and saturated saline (20 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the title compound (813 mg, 84%) was obtained as a colorless compound.

FAB-MS (LR): m / z 485
(MH ⁺ , 72.9%). FAB-MS (HR): Calcd for C 22 H 41 N 2 O 6
Si ₂ : 485.2500. Found: 485.2531. _{^{1 H-NMR (CDCl 3)}} δ; 8.20 (brs, 1H, N
_{H, D 2 O exchangeable),} 7.51 (s, 1H, H-
6), 6.22 (d, 1H , H-1 ', J 1', 2 '= 8.3
Hz), 4.22 (brs, 1H, H-4 '), 4.19 (d,
1H, H-2 ', J 2', 1 '= 8.3Hz), 3.93 (t,
2H, H-5'ab), 1.97 (s, 3H, 5-Me) 0.
92, 0.86 (each s, each 9H, t-Bu),
0.11, 0.09, 0.08, 0.00 (each s, each
3H, Me). Anal. _{Calcd for C 22 H 40 N 2} O 6 Si 2: C, 54.
51; H, 8.32; N, 5.78. Found: C, 54.3
9; H, 8.07; N, 5.85.

(3) 1- (2-O-tert-butyldimethylsilyl-3-oxo-β-D-ribo-pentofuranosyl) -5-methyluracil 1- (2,5-O-di-tert) -Butyldimethylsilyl-3-oxo-β-D-ribo-pentofuranosyl)-
A mixture (4.5 mL) of trifluoroacetic acid: water = 10: 1 was added to 5-methyluracil (730 mg, 1.50 mmol), and the mixture was stirred at 0 ° C. for 20 minutes. The reaction solution was partitioned between chloroform (25 mL) and ice water (25 mL), and the organic layer was washed with water (20 mL). Without discarding water, a saturated aqueous sodium hydrogen carbonate solution was added until the aqueous layer became neutral. The extract was washed, further washed with water (20 mL) and saturated saline (20 mL), dried over anhydrous sodium sulfate, filtered, the filtrate was evaporated under reduced pressure, and the residue was subjected to short silica gel column chromatography (φ3.6 ×). Purify with 9 cm, 50% ethyl acetate / hexane) to give the title compound (460 mg, 8
2%) as a colorless substance.

¹ H-NMR (CDCl ₃ ) δ; 8.38 (br
_{s, 1H, NH, D 2} O exchangeable), 7.23
(D, 1H, H-6 , J 6, Me = 1.0Hz), 5.64
(D, 1H, H-1 ', J 1', 2 '= 7.7Hz), 4.76
(D, 1H, H-2 ', J 2', 1 '= 7.7Hz), 4.25
(Dd, 1H, H-4 ', J 4', 5'a = 2.7Hz, J 4 ',
5'b = 1.9 Hz), 3.95 (ddd, 1H, H-5'a, J
_{5 'a, 4' = 2.7Hz} , J 5 'a, OH = 2.8Hz, J 5' a,
5'b = 12.1 Hz), 3.91 (ddd, 1H, H-5'b,
J5'b, 4 '= 1.9Hz, J 5' b, OH = 8.2Hz, J 5 '
a, 5'b = 12.1 Hz), 3.00 (dd, 1H, 5'-O
H, JOH, 5'a = 2.8Hz, JOH, 5'b = 8.2H
z), 1.97 (d, 3H, 5-Me, JMe, 6 = 1.0H
z), 0.86 (s, 9H, t-Bu), 0.12, 0.0
3 (each s, each 3H, Me). Anal. Calcd for C ₁₆ H ₂₆ N ₂ O ₆ Si: C, 51.8
7; H, 7.07; N, 7.56. Found: C, 51.6
1; H, 7.15; N, 7.45.

(4) 1- (2-O-tert-butyldimethylsilyl-3-C-trimethylsilylethynyl-β
-D-ribo-pentofuranosyl) -5-methyluracil 1- (2-O-tert-butyldimethylsilyl-3-
Oxo-β-D-ribo-pentofuranosyl) -5-methyluracil (4.00 g, 10.8 mmol) was added to Reference Example 2 described below.
The reaction was carried out under the same conditions as described above. The reaction was completed in 2 hours. The reaction mixture was diluted with ethyl acetate (300 mL) and water (10 mL).
0 mL), and the organic layer was washed with a saturated aqueous solution of sodium hydrogencarbonate (100 mL x 2), water (100 mL), and saturated saline (100 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was subjected to silica gel column chromatography (φ7.5 × 14 c).
m, 45% ethyl acetate / hexane) to give the title compound (3.85 g, 76%) as a pale yellow solid.

FAB-MS (LR): m / z 469
(MH ⁺ , 87.5%). FAB-MS (HR): Calcd for C ₂₁ H ₃₇ N ₂ O ₆
Si _2: 469.2188. Found: 469.2218. _{^{1 H-NMR (CDCl 3)}} δ; 8.17 (brs, 1H, N
_{H, D 2 O exchangeable),} 7.50 (d, 1H, H-
6, J ₆ , Me = 1.0 Hz), 5.81 (d, 1H, H−
1 ′, J ₁ ′, 2 ′ = 7.0 Hz), 4.49 (d, 1H, H−
2 ′, J ₂ ′, 1 ′ = 7.0 Hz), 4.18 (t, 1H, H−
_{4 ', J 4', 5'a} = J 4 ', 5'b = 2.8Hz), 4.02
(Ddd, 1H, H-5'a , J 5 'a, 4' = 2.8Hz, J 5 '
a, OH = 6.2 Hz, J ₅ 'a, 5'b = 12.5 Hz), 3.
89 (ddd, 1H, H- 5'b, J 5 'b, 4' = 2.8Hz,
J ₅ 'b, OH = 6.2 Hz, J ₅ ' a, 5'b = 12.5 Hz),
3.30 (s, 1H, 3'- OH, D 2 O exchangeabl
e), 2.49 (t, 1H, 5'-OH, JOH, 5'a = J
_{OH, 5'b = 6.2Hz D 2 O} exchangeable), 1.9
5 (d, 3H, 5-Me, JMe, 6 = 1.0 Hz), 0.9
0 (s, 9H, t-Bu), 0.20 (s, 9H, TM
S), 0.14, 0.00 (each s, each 3H, M
e). Anal. _{Calcd for: C 21 H 36 N} 2 O 6 Si 2: C, 53.
82; H, 7.74; N, 5.98. Found: C, 54.
03; H, 7.74; N, 5.94.

Reference Example 2 1- (2-O-tert-butyldimethylsilyl-3-)
Preparation of C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) uracil Cerium chloride heptahydrate (38.0 g, 102 mmol) was depressurized with a vacuum pump and stirred at 150 ° C. for 7 hours. The mixture was returned to normal pressure while introducing argon gas, tetrahydrofuran (120 mL) was added under ice cooling, and the mixture was returned to room temperature and stirred overnight. Separately, tetrahydrofuran (70 mL) was added to trimethylsilylacetylene (14.5 mL, 102 mmol), and the mixture was cooled to -20 ° C under an argon atmosphere, and a hexane solution of butyllithium (1.68 M, 61 mL) was added.
L, 102 mmol) over 30 minutes.
Minutes. Add this to the cerium chloride suspension
The solution was cooled to 78 ° C. and cannulated for 20 minutes. The resulting yellow suspension was stirred at the same temperature for 60 minutes and 1- (2-O-tert-butyldimethylsilyl-
A solution of 3-oxo-β-D-ribo-pentofuranosyl) -uracil (6.0 g, 17.0 mmol) in tetrahydrofuran (34.0 mL) was added dropwise over 15 minutes.
Stirred for hours. Acetic acid (15.0 mL) was added to the reaction mixture, and after the temperature was raised to room temperature, the mixture was partitioned between ethyl acetate (500 mL) and water (200 mL).
2), washed with saturated saline (200 mL) and dried over anhydrous sodium sulfate. After filtration, the solvent was distilled off under reduced pressure. The residue was suspended in hexane and collected by filtration to give the title compound (6.
63 g, 86.7%) as a solid.

FAB-MS (LR): m / z 455
(MH ⁺ , 64.8%). FAB-MS (HR): Calcd for C 20 H 35 N 2 O 6
Si ₂ : 455.2031. Found: 455.2004. ¹ H-NMR (DMSO-d ₆ ) δ; 11.37 (brs, 1
H, NH, D ₂ O exchangeable), 8.23 (d, 1
_{H, H-6, J 6} , 5 = 8.1Hz), 5.88 (d, 1
H, H-1 ', J 1', 2 '= 7.3Hz), 5.80 (s, 1
H, 3'-OH, D ₂ Oexchangeable), 5.71 (dd,
_{1H, H-5, J 5} , 6 = 8.1Hz), 5.10 (br s,
_{1H, 5'-OH, D 2} O exchangeable), 4.34
(D, 1H, H-2 ', J 2', 1 '= 7.3Hz), 3.94
(T, 1H, H-4 '), 3.73 (m, 1H, H-5')
a, J ₅ a ′, ₅ ′ b = 11.8 Hz), 3.66 (m, 1 H, H
−5′b, J ₅ ′ b, 5′a = 11.8 Hz), 0.81 (s, 9
H, t-Bu), 0.14 (s, 9H, TMS), 0.8
8, -0.05 (each s, each 3H, Me). Anal. Calcd for C ₂₀ H ₃₄ N ₂ O ₆ Si ₂ · 0.1H
₂ O: C, 52.63; H, 7.55; N, 6.14. Fou
nd: C, 52.39; H, 7.80; N, 6.09.

Reference Example 3 9- (2-O-tert-butyldimethylsilyl-3-
C-triisopropylsilylethynyl-β-D-ribo-
Production of pentofuranosyl) adenine (1) 9- (2,5-O-di-tert-butyldimethylsilyl-β-D-ribo-pentofuranosyl) adenine TBS chloride (8.10 g, 53.7 mmol), Silver nitrate (9.20 g, 54.2 mmol) was added to tetrahydrofuran (2
00 mL) and stirred for 5 minutes. Adenosine (5.35 g, 20.0 mmol) and pyridine (8.90 m
L, 110 mmol), and the mixture was stirred at room temperature for 17.5 hours under an argon atmosphere. The reaction mixture was filtered, ethanol (10 mL) was added to the filtrate, and the solvent was distilled off under reduced pressure. The residue was partitioned between ethyl acetate (250 mL) and water (200 mL containing 1N aqueous hydrochloric acid solution 10 mL), and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution (200 mL) and water (2 mL).
(200 mL) and saturated saline (200 mL), and dried over anhydrous sodium sulfate. After filtration with a cotton plug, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was dissolved in a small amount of chloroform.
Silica gel column chromatography (7.5 × 15 +
Purification by 1.2 cm, 50/25/25 to 60/20/20% ethyl acetate / hexane / chloroform) afforded the title compound (5.44 g, 55%) as a colorless crystalline material.

FAB-MS (LR): m / z 496
(MH ⁺ , 100%). FAB-MS (HR): Calcd for C 22 H 42 N 5 O 4
Si _2: 496.2773. Found: 496.2795. _{^{1 H-NMR (CDCl 3)}} δ; 8.35 (s, 1H, H-
8), 8.21 (s, 1H, H-2), 6.10 (d, 1
H, H-1 ', J 1', 2 '= 5.0Hz), 5.62 (br
_{s, 2H, NH 2, D} 2 O exchangeable), 4.65
(T, 1H, H-2 ', J 2', 1 '= J 2', 3 '= 5.0H
z), 4.28 (dd, 1H , H-3 ', J 3', 2 '= 5.0
Hz, J ₃ ′, OH = 8.2 Hz), 4.20 (dd, 1H, H
_{-4 ', J 4', 5'a} = 2.6Hz, J 4 ', 5'b = 2.5H
z), 4.01 (dd, 1H , H-5'a, J 5 'a, 4' = 2.
6 Hz, J ₅ 'a, 5'b = 11.4 Hz), 3.86 (dd, 1
_{H, H-5'b, J 5} 'b, 4' = 2.5Hz, J 5 'b, 5'a =
11.4 Hz), 2.74 (d, 1H, 3'-OH, d, 1
H, 3'-OH, JOH, 3 '= 8.2Hz, D 2 O excha
ngeable), 0.96, 0.84 (each s, each 9H,
t-Bu), 0.15, 0.14, -0.03, -0.14
(Each s, each 3H, Me). Anal. _{Calcd for C 22 H 41 N 5} O 4 Si 2: C, 53.
18; H, 8.29; N, 14.28. Found: C, 5
3.30; H, 8.34; N, 14.13.

(2) 9- (2,5-O-di-tert-
Butyldimethylsilyl-3-oxo-β-D-ribo-pentofuranosyl) adenine To methylene chloride (5.00 mL) was added molecular sieves 4A (1.00 g) heated in a microwave for 80 seconds,
Chromium oxide (300 mg, 3.00 mmol) was quickly weighed and cooled with ice under an argon atmosphere. While stirring the mixture, pyridine (240 mL, 3.00 mmol) was added and the mixture was stirred for 30 minutes. Acetic anhydride (280 mL, 3.00 mmol) was added and the mixture was stirred for 10 minutes. Add methylene chloride (5m
9- (2,5-O-di-tert-butyldimethylsilyl-β-D-ribo-pentofuranosyl) dissolved in L)
Adenine (500 mg, 1.00 mmol) was added, and the mixture was stirred at 0 ° C. for 30 minutes. The reaction mixture was treated with ethyl acetate (100
mL), the mixture was stirred for 30 minutes, and suction-filtered with a funnel. About half the solvent was distilled off from the filtrate under reduced pressure, and water (50 mL) was added.
The mixture was washed with a 1N aqueous hydrochloric acid solution (2 mL), and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution (50 mL ×
2) Washed with water (50 mL) and saturated saline (30 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was suspended in hexane. The solid was collected by filtration to give the title compound (463 mg, 93%) as a colorless crystalline compound.

FAB-MS (LR): m / z 494
(MH ⁺ , 60.8%). FAB-MS (HR): Calcd for C 22 H 40 N 5 O 4
Si _2: 494.2616. Found: 494.2639. _{^{1 H-NMR (CDCl 3)}} δ; 8.37 (s, 1H, H-
8), 8.14 (s, 1H, H-2), 6.13 (d, 1
H, H-1 ', J 1', 2 '= 8.2Hz), 5.65 (brs,
2H, NH ₂ , D ₂ O exchangeable), 4.94 (d, 1
H, H-2 ′, J ₂ ′, 1 ′ = 8.2 Hz), 4.30 (br
s, 1H, H-4 '), 3.99 (dd, 1H, H-5'a,
J ₅ 'a, 4' = 2.4 Hz, J ₅ 'a, 5'b = 11.3 Hz),
3.95 (dd, 1H, H- 5'b, J 5 'b, 4' = 2.3H
z, J ₅ 'b, 5'a = 11.3 Hz), 0.92, 0.73 (ea
ch s, each 9H, t-Bu), 0.11, 0.07,-
0.01, -0.20 (each s, each 3H, Me). Anal. _{Calcd for C 22 H 39 N 5} O 4 Si 2: C, 53.
52; H, 7.96; N, 14.18. Found: C, 5
3.40; H, 7.88; N, 14.18.

(3) 9- (2-O-tert-butyldimethylsilyl-3-oxo-β-D-ribo-pentofuranosyl) adenine 9- (2,5-O-di-tert-butyldimethylsilyl) To a mixture of -3-oxo-β-D-ribo-pentofuranosyl) adenine (250 mg, 0.50 mmol) and a mixture of trifluoroacetic acid: water = 10: 1 (1.50 mL) was added, and the mixture was added at 0 ° C.
For 20 minutes. The chloroform solution (25m
L) and ice water (25 mL), and the organic layer was separated with water (20 mL).
L), without removing the water, adding an aqueous saturated sodium hydrogen carbonate solution until the aqueous layer becomes neutral, and washing again. Further, washing with water (20 mL) and a saturated saline solution (20 mL), and then washing with anhydrous sodium sulfate. After drying and filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was scraped off with chloroform / hexane using a spatula.
The obtained solid was suspended in hexane and the solid was collected by filtration to obtain the title compound (146 mg, 76%).

FAB-MS (LR): m / z 380
(MH ⁺ , 6.7%). FAB-MS (HR): Calcd for C ₁₆ H ₂₆ N ₅ O ₄
Si: 380.1752. Found: 380.1779. ^{1 H-NMR (DMSO-d} 6) δ; 8.51 (s, 1H,
H-8), 8.16 (s, 1H, H-2), 7.43 (br
_{s, 2H, NH 2, D} 2 O exchangeable), 6.16
(D, 1H, H-1 ', J 1', 2 '= 8.1Hz), 5.54
(Br s, 1H, 5'- OH, D 2 O exchangeable),
5.07 (d, 1H, H- 2 ', J 2', 1 '= 8.1Hz),
4.42 (t like dd, 1H, H- ₄ ', J4', 5'a =
2.5 Hz, J ₄ ', 5'b = 2.9 Hz), 3.71 (dd, 1
_{H, H-5'a, J 5} 'a, 4' = 2.5Hz, J 5 'a, 5'b =
12.6Hz), 3.66 (dd, 1H , H-5'b, J 5 'b,
4 '= 2.9 Hz, J ₅ ' b, 5'a = 12.6 Hz), 0.67
(S, 9H, t-Bu), -0.14, -0.29 (each
s, each 3H, Me). Anal. _{Calcd for C 16 H 25 N 5} O 4 Si. 15H ₂ O:
C, 50.28; H, 6.67; N, 18.32. Found:
C, 50.56; H, 6.76; N, 18.04.

(4) 9- (2-O-tert-butyldimethylsilyl-3-C-triisopropylsilylethynyl-β-D-ribo-pentofuranosyl) adenine cerium chloride heptahydrate (23.0 g, (61.7 mmol) was reduced in pressure with a vacuum pump and stirred at 160 ° C. for 4.5 hours. The mixture was returned to normal pressure while introducing argon gas, tetrahydrofuran (75.0 mL) was added under ice cooling, and the mixture was returned to room temperature and stirred overnight. Separately from this, triisopropylsilylacetylene (13.8 mL, 61.6 mmol) in tetrahydrofuran (20 mL) was added, and the mixture was added under argon atmosphere.
C. and cooled to a hexane solution of butyllithium (1.68).
M, 36.7 mL, 61.7 mmol) was added dropwise over 10 minutes, and the mixture was stirred at the same temperature for 30 minutes. This was cooled to -15 ° C, and the suspension of cerium chloride was cooled to -78 ° C and cannulated for 20 minutes. The resulting yellow suspension was stirred at the same temperature for 90 minutes and 9- (2-O-
tert-butyldimethylsilyl-3-oxo-β-D
-Ribo-pentofuranosyl) adenine (3.90 g, 1
0.3 mmol) in tetrahydrofuran (150 mL) was added dropwise over 10 minutes, and the mixture was stirred at -78 ° C for 60 minutes. Acetic acid (8.80 mL) was added to the reaction mixture, and after the temperature was raised to room temperature, the mixture was partitioned between ethyl acetate (300 mL) and water (100 mL).
mL × 2), water (100 mL), saturated saline (100 mL)
L) and dried over anhydrous sodium sulfate. After filtration, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (φ7.5 × 15 cm, 50-75% ethyl acetate / hexane) to give the title compound (3.93).
g, 68.1%) as a colorless solid.

FAB-MS (LR): m / z 562
(MH ⁺ , 58.8%). FAB-MS (HR): Calcd for C 27 H 48 N 5 O 4
Si _2: 562.3242. Found: 562.3239. _{^{1 H-NMR (CDCl 3)}} δ; 8.39 (s, 1H, H-
8), 7.79 (s, 1H, H-2), 6.31 (dd, 1
H, 5'-OH, JOH, 5'a = 11.3Hz, JOH,
_{5'b = 2.3Hz, D 2 O exchangeable} ), 5.75
(D, 1H, H-1 ', J 1', 2 '= 7.6 Hz), 5.6
7 (br s, 2H, NH 2, D 2 O exchangeable), 5.
21 (d, 1H, H- 2 ', J 2', 1 '= 7.6Hz), 4.
31 (br.s, 1H, H-4 '), 4.02 (dd, 1H, H
_{-5'a, J 5 'a, OH} = 11.3Hz, J 5 a', 5'b = 1
3.0Hz), 3.96 (dd, 1H , H-5'b, J 5 'b,
OH '= 2.3 Hz, J ₅ ' b, 5'a = 13.0 Hz), 3.2
1 (s, 1H, 3'- OH, D 2 O exchangeable), 1.
12 (s, 21H, -Sii- Pr 3), 0.81 (s, 9
H, t-Bu), 0.03, -0.49 (each s, each
3H, Me). Anal. _{Calcd for C 27 H 47 N 5} O 4 Si 2: C, 57.
72; H, 8.43; N, 12.46. Found: C, 5
7.63; H, 8.45; N, 12.46.

Example 1 Preparation of 1- (2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) uracil (compound 1) (1) 1- (3,5-di-O- Benzoyl-2-Ot
tert-butyldimethylsilyl-3-C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) uracil 1- (2-O-tert-butyldimethylsilyl-3-
C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) uracil (2.65 g, 5.80 mmol) was dissolved in acetonitrile (60 mL) and benzoic anhydride (3.
90 g, 17.2 mmol), DMAP (2.10 g, 17.2 m)
mol), and the mixture was stirred at room temperature for 2 hours under an argon atmosphere. After 7 to 8 ice particles were added to the reaction mixture, it was confirmed by TLC that spots derived from benzoic anhydride had disappeared, and the solvent was distilled off under reduced pressure. The residue was partitioned between ethyl acetate (50 mL) and water (50 mL) plus a 1N aqueous hydrochloric acid solution (5 mL), and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution (5 mL).
0 × 2), water (50 mL) and saturated saline (50 mL), and dried over anhydrous sodium sulfate. After filtration,
The filtrate was evaporated under reduced pressure. The residue was subjected to silica gel column chromatography (first time: φ3.6 × 20 cm, 33%
Ethyl acetate / hexane, second time: 3.5 × 18 cm, 50
% Ether / hexane) to give the title compound (3.26 g, 84%) as a colorless substance.

FAB-MS (LR): m / z 663
(MH ⁺ , 18.8%). FAB-MS (HR): Calcd for C 34 H 43 N 2 O 8
Si _2: 663.2555. Found: 663.2553. ¹ H-NMR (CDCl ₃ ) δ; 8.13 to 8.05, 7.6
2 to 7.41, _{[11H, Bz, NH, D 2} O exchangea
ble (NH)], 7.78 (d, 1H, H -6, J 6, 5 =
8.2Hz), 6.21 (d, 1H , H-1 ', J 1', 2 '=
4.2Hz), 5.71 (d, 1H , H-2 ', J 2', 1 '=
4.2Hz), 5.67 (dd, 1H , H-5, J 5, 6 =
8.2Hz), 4.75 (dd, 1H , H-5'a, J 5 'a,
4 '= 6.2 Hz, J ₅ ' a, 5'b = 12.3 Hz), 4.68
(Dd, 1H, H-5'b , J 5 'b, 4' = 2.5Hz, J 5 '
b, 5'a = 12.3Hz), 4.41 (dd, 1H, H-
_{4 ', J 4', 5'a} = 6.2Hz, J 4 ', 5'b = 2.5H
z), 0.78 (s, 9H, t-Bu), 0.26, 0.15
(Each s, each 3H, Me), 0.14 (s, 9H,
TMS). Anal. _{Calcd for C 34 H 42 N 2} O 8 Si 2 · 0.55H 2
O: C, 60.70; H, 6.46; N, 4.16. Foun
d: C, 60.94; H, 6.24; N, 3.86.

(2) 1- (3,5-di-O-benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) uracil 1- (3,5-di-O-benzoyl-2) -O-tert
-Butyldimethylsilyl-3-C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) uracil (1.00 g, 1.50 mmol) was added to tetrahydrofuran (1
5 mL), and acetic acid (220 μL, 3.75 mmol),
Tetrabutylammonium fluoride (TBAF) /
Tetrahydrofuran solution (1N, 3.6 mL, 3.6 mmol)
l) was added and stirred at room temperature for 5 minutes. The solvent was distilled off from the reaction solution under reduced pressure, and the residue was purified by silica gel column chromatography (φ3.1 × 21.5 + 1.5 cm, 50-67% ethyl acetate / hexane) to give the title compound (690
mg, 96%) as a colorless substance.

FAB-MS (LR): m / z 477
(MH ⁺ , 20.8%). FAB-MS (HR): Calcd for C ₂₅ H ₂₁ N
₂ O ₈ : 477.1297. Found: 477.1313 ¹ H-NMR (CDCl ₃ ) δ; 8.54 (br, 1H, N
_{H, D 2 O exchangeable),} 8.09~8.04,7.6
2-7.41 (10H, Bz), 7.65 (d, 1H, H-
6, J ₆ , 5 = 8.2 Hz), 6.34 (d, 1H, H−
1 ′, J ₁ ′, 2 ′ = 4.5 Hz), 5.67 (d, 1H, H−
_{5, J 5, 6 = 8.2Hz} ), 5.63 (d, 1H, H-
2 ′, J ₂ ′, 1 ′ = 4.5 Hz), 4.79 (dd, 1H, H
_{-5'a, J 5 'a, 4} ' = 5.7Hz, J 5 'a, 5'b = 12.3
Hz), 4.73 (dd, 1H , H-5'b, J 5 'b, 4' =
3.1 Hz, J ₅ 'b, 5'a = 12.3 Hz), 4.49 (dd,
1H, H-4 ', J 4', 5'a = 5.7Hz, J 4 ', 5'b =
3.1Hz), 3.35 (br s, 1H, 2'-OH, D 2 O
exchangeable), 2.78 (s, 1H, 3'-CC)
CH). Anal. _{Calcd for C 25 H 20 N 2} O 8 · 0.5H 2 O:
C, 61.86; H, 4.36; N, 5.77. Found:
C, 61.91; H, 4.33; N, 5.47.

(3) 1- (3,5-di-O-benzoyl-2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) uracil 1- (3,5-di-O -Benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) uracil (650
mg, 1.36 mmol) in methylene chloride (14 mL) and 1,1'-thiocarbonyldiimidazole (540 mL).
g, 2.73 mmol) at room temperature under an argon atmosphere.
Stirred for hours. The reaction solution was partitioned between chloroform (10 mL) and water (30 mL), and the organic layer was separated with water (30 mL ×
2) After washing with saturated saline (30 mL), drying over anhydrous sodium sulfate, filtration and removal of the solvent under reduced pressure. Benzene (100 mL) and tetrahydrofuran (20 mL) were added to the residue.
L) and dissolved. AIBN (67.0 mg, 0.41 mm)
ol), tributyltin hydride (1.10 mL, 4.10 mL).
09 mmol), and the mixture was heated and stirred at 80 ° C. for 5 minutes. The reaction solution was cooled to room temperature, and 3 spoons of anhydrous potassium fluoride and water (3
mL) and stirred vigorously for 4 hours. Further, anhydrous sodium sulfate was added, the mixture was filtered through celite, and the solvent in the filtrate was distilled off under reduced pressure. The residue was partitioned between ethyl acetate (30 mL) and a 1M aqueous solution of potassium fluoride (30 mL).
L) and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was purified by silica gel column chromatography (φ3.5 × 10 cm, 50% ethyl acetate / hexane), and partitioned between acetonitrile (80 mL) and hexane (50 mL). Then, the mixture was partitioned between acetonitrile (80 mL) and hexane (50 mL), and the acetonitrile layer was washed with hexane (50 mL × 2). The solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (φ3.5 × 10 cm, 50% ethyl acetate / hexane) to give the title compound (368 m 2).
g, 59%) as a colorless substance.

EI-MS (LR): m / z 460
(M ⁺ , 0.02%) EI-MS (HR): Calcd for C ₂₅ H ₂₀ N ₂ O ₇ :
460.1269. Found: 460.1259 ¹ H-NMR (CDCl ₃ ) δ; 8.62 (brs, 1H, N
_{H, D 2 O exchangeable),} 8.09~7.44 (11
H, Bz, H-6), 6.37 (dd, 1H, H-1 ',
J ₁ ′, ₂ ′ a = 6.2 Hz, J ₁ ′, ₂ ′ b = 7.4 Hz), 5.67
(D, 1H, H-5 , J 5, 6 = 8.2Hz), 4.88 (d,
_{2H, H-5'ab, J 5} 'ab, 4' = 4.6Hz), 4.78
(T, 1H, H- ₄ ', J4', 5'ab = 4.6Hz,), 3.
20 (dd, 1H, H- 2'a, J 2 'a, 1' = 6.2Hz, J 2 '
_{a, 2 'b = 14.5Hz)} , 2.85 (s, 1H, -C-C≡
CH), 2.79 (dd, 1H , H-2'b, J 2 'b, 1' = 7.
4 Hz, J ₂ 'b, 2'a = 14.5 Hz). Anal. _{Calcd for C 25 H 20 N 2} O 7. _{5H 2 O: C, 63.96;} H, 4.51; N, 5.96.
Found: C, 64.22; H, 4.52; N, 5.75.

(4) 1- (2-Deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) uracil 1- (3,5-di-O-benzoyl-2-deoxy-3
-C-ethynyl-β-D-ribo-pentofuranosyl) uracil (50.0 mg, 0.11 mmol) was added to methanol (2m
L), a 5N sodium methylate / methanol solution (26 μL, 0.13 mmol) was added, and the mixture was stirred at room temperature for 2.5 hours under an argon atmosphere. The reaction solution was neutralized by adding a 1N aqueous hydrochloric acid solution, the solvent was distilled off under reduced pressure, dissolved in a small amount of methanol, adsorbed on silica gel, the solvent was distilled off again under reduced pressure, and the residue was subjected to silica gel column chromatography (φ1.1 × 11 + 1 cm). , 10% methanol / chloroform) to give Compound 1 (26.0 mg, 95%).
%) As a colorless crystalline material. The sample for analysis was obtained by recrystallization from ethanol.

EI-MS (LR): m / z 252 (M
⁺ , 1.10%) EI-MS (HR): Calcd for C ₁₁ H ₁₂ N ₂ O ₅ :
252.0745. Found: 252.0752 ¹ H-NMR (D ₂ O) δ; 7.99 (d, 1H, H-6,
_{J 6, 5 = 8.2Hz),} 6.28 (dd, 1H, H-1 ',
J ₁ ′, ₂ ′ a = 6.2 Hz, J ₁ ′, ₂ ′ b = 7.4 Hz), 5.91
(D, 1H, H-5 , J 5, 6 = 8.2Hz), 4.11 (m,
1H, H-4 '), 3.93 (m, 2H, H-5'ab),
3.18 (s, 1H, -CC = CH), 2.74 (dd,
_{1H, H-2'a, J 2} 'a, 1' = 6.2Hz, J 2 'a, 2' b =
13.9Hz), 2.59 (dd, 1H , H-2'b, J 2 'b,
1 ′ = 7.4 Hz, J ₂ ′ b, ₂ ′ a = 13.9 Hz). 13C-NMR (MeOH) δ: 166.18 (C), 1
52.2 (C), 142.20 (C), 102.60 (C
H), 89.99 (CH), 85.74 (CH), 83.
25 (CH), 76.78 (C), 73.94 (C), 6
_{3.34 (CH 2), 47.49 (} CH 2) Anal. Calcd for C ₁₁ H ₁₂ N ₂ O ₅ : C, 52.3
8; H, 4.80; N, 11.10. Found: C, 52.
12; H, 4.86; N, 11.00.

Example 2 Preparation of 1- (2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) cytosine (Compound 2) (1) 1- (3,5-di-O- Benzoyl-2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) cytosine 1- (3,5-di-O-benzoyl-2-deoxy-3
-C-ethynyl-β-D-ribo-pentofuranosyl) uracil (150 mg, 0.33 mmol) was dissolved in acetonitrile (3 mL), and triisopropylbenzenesulfonyl chloride (TPS chloride) (200 mg, 0.66 m
mol), triethylamine (92 μL, 0.66 mmol),
DMAP (80 mg, 0.65 mmol) was added, and the mixture was stirred at room temperature under an argon atmosphere for 1 hour. Concentrated aqueous ammonia (3.0 mL) was added, and the mixture was stirred at room temperature for 20 minutes. The reaction solution was partitioned between ethyl acetate (30 mL) and water (10 mL), and the organic layer was separated with a 0.1N aqueous hydrochloric acid solution (10 mL) and a 0.5N aqueous solution.
The extract was washed with an aqueous hydrochloric acid solution (10 mL), water (10 mL × 4) and saturated saline (10 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure, the residue was dissolved in a small amount of methanol, and adsorbed by silica gel column chromatography. Then, the solvent was again distilled off under reduced pressure. ,
Purification by 6% methanol / chloroform) gave the title compound (136 mg, 91%) as a colorless solid.

EI-MS (LR): m / z 459
(M ⁺ , 0.04%) EI-MS (HR): Calcd for C ₂₅ H ₂₁ N ₃ O ₆ :
459.1429. Found: 459.1412. ¹ H-NMR (CDCl ₃ ) δ; 8.10 to 8.00, 7.6
2 to 7.42 (m, 10H, Bz), 7.76 (d, 1H,
_{H-6, J 6, 5} = 7.5Hz), 6.37 (dd, 1H, H-
1 ′, J ₁ ′, ₂ ′ a = 5.9 Hz, J ₁ ′, ₂ ′ b = 7.4 Hz), 6.
30 to 5.00 (br s, 2H, NH ₂ , D ₂ O exchangea
ble), 5.63 (d, 1H , H-5, J 5, 6 = 7.5H
z), 4.89-4.83 (m, 3H, H-5'ab, H-
4 '), 3.38 (dd, 1H, H-2'a, J 2' a, 1 '= 5.
9 Hz, J ₂ 'a, ₂ ' b = 14.5 Hz), 2.78 (s, 1 H,
-CC-CH), 2.69 (dd, 1H, H-2'b,
_{J 2 'b, 1' =} 7.4Hz, J 2 'b, 2' a = 14.5Hz). Anal. Calcd for C ₂₅ H ₂₁ N ₃ O ₆ . 65H ₂ O:
C, 63.73; H, 4.77; N, 8.92. Found:
C, 63.94; H, 4.66; N, 8.62.

(2) 1- (2-Deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) cytosine 1- (3,5-di-O-benzoyl-2-deoxy-3
-C-ethynyl-β-D-ribo-pentofuranosyl) cytosine (200 mg, 0.44 mmol) was treated with methanol (8.8).
mL), a 5N sodium methylate / methanol solution (100 μL, 1.20 mmol) was added, and the mixture was stirred at room temperature under an argon atmosphere for 1 hour. The reaction solution was neutralized by adding a 1N aqueous hydrochloric acid solution, and the solvent was distilled off under reduced pressure. The residue was dissolved in a small amount of methanol, and adsorbed on silica gel column chromatography. Then, the solvent was again distilled off under reduced pressure, and silica gel column chromatography (φ1.0 × 10 +
The residue was purified with 1 cm, 20% methanol / chloroform) and further partitioned between water (10 mL) and chloroform (10 mL). The aqueous layer was washed with chloroform (10 mL × 5), and the solvent was distilled off under reduced pressure. Compound 2 (109 mg,
quant) as a colorless crystalline material. The sample for analysis was obtained as a hydrochloride and recrystallized from ethanol. mp:
105 ° C

EI-MS (LR): m / z 251 (M
⁺ , 2.90%). EI-MS (HR): Calcd for C ₁₁ H ₁₃ N ₃ O ₄ :
251.0905. Found: 251.0932. _{^{1 H-NMR (D 2 O}} ) δ; 8.17 (d, 1H, H-6,
_{J 6, 5 = 7.9Hz),} 6.22 (dd, 1H, H-1 ',
J ₁ ′, ₂ ′ a = 6.3 Hz, J ₁ ′, 2′b = 6.7 Hz), 6.2
1 (d, 1H, H- 5, J 5, 6 = 7.9Hz), 4.17 (d
d, 1H, H-4 ' , J 4', 5 'a = 3.6Hz, J 4', 5 'b =
6.0Hz), 3.98 (dd, 1H , H-5'a, J 5 'a, 4'
= 3.6 Hz, J ₅ 'a, ₅ ' b = 12.5 Hz), 3.93 (dd,
_{1H, H-5'b, J 5} 'b, 4' = 6.0Hz, J 5 'b, 5' a = 1
2.5 Hz), 3.15 (s, 1H, -CC = CH),
2.80 (dd, 1H, H- 2'a, J 2 'a, 1' = 6.3Hz,
_{J 2 'a, 2' b} = 14.0Hz), 2.57 (dd, 1H, H-
_{2'b, J 2 'b, 1} ' = 6.7Hz, J 2 'b, 2' a = 14.0H
z). ¹³ C-NMR (MeOH-d ₄ ) δ: 161.51 (C), 152.2 (C), 148.94
(C), 146.38 (CH), 94.53 (CH), 9
0.76 (CH), 83.25 (CH), 87.38 (C
H), 82.89 (CH), 77.05 (C), 73.9
8 (C), 63.07 (CH 2), 47.90 (CH 2) Anal. Calcd for C ₁₁ H ₁₄ ClN ₃ O ₄ . 45H ₂ O:
C, 44.66; H, 5.08; N, 14.21. Foun
d: C, 44.89; H, 4.86; N, 13.92.

Example 3 Preparation of 1- (2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil (compound 3) (1) 1- (2-O- tert-butyldimethylsilyl-3,5-di-O-benzoyl-3-C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) -5
-Methyluracil 1- (2-O-tert-butyldimethylsilyl-3-
C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil (470 mg, 1.00
mmol) was reacted in the same manner as in Example 1 (1). The reaction is 2
Completed in time. Two drops of ice were added to the reaction solution, and on TLC,
After confirming the disappearance of spots derived from benzoic acid, the solvent was distilled off under reduced pressure, and the residue was partitioned between ethyl acetate (20 mL) and water (20 mL) added with a 1N aqueous hydrochloric acid solution (5 mL), and the organic layer was saturated. Aqueous solution of sodium hydrogen carbonate (20mL ×
2), washed with water (20 mL) and saturated saline (20 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was purified by silica gel column chromatography (φ2.7 × 18 cm, 29% ethyl acetate / hexane) to give the title compound (618 mg, 91%).
Was obtained as a colorless substance.

FAB-MS (LR): m / z 677
(MH ⁺ , 43.8%). FAB-MS (HR): Calcd for C 35 H 45 N 2 O 8
Si ₂ : 677.2711. Found: 677.2755. _{^{1 H-NMR (CDCl 3)}} δ; 8.16~7.44 [12
H, Bz, NH, H-6, D ₂ O exchangeable (N
H)], 6.33, (d, 1H, H-1 ', J 1', 2 '= 5.
8Hz), 5.82 (d, 1H , H-2 ', J 2', 1 '= 5.8
Hz), 4.73 (dd, 1H , H-5'a, J 5 'a, 4' = 5.
0 Hz, J ₅ 'a, ₅ ' b = 12.4 Hz), 4.67 (dd, 1
_{H, H-5'b, J 5} 'b, 4' = 2.7Hz, J 5 'a, 5' b = 12.
4Hz), 4.40 (dd, 1H , H-4 ', J 4', 5 'a = 5.
0 Hz, J ₄ ′, ₅ ′ b = 5-Me), 0.87 (s, 9 H, t−
Bu), 0.25, 0.15 (each s, each 3H, M
e), 0.10 (s, 9H, TMS). Anal. _{Calcd for: C 35 H 44 N} 2 O 8 Si 2: C, 62.
10; H, 6.55; N, 4.14. Found: C, 62.
15; H, 6.58; N, 4.35.

(2) 1- (3,5-di-O-benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil 1- (2-O-tert-butyl Dimethylsilyl-3,
5-Di-O-benzoyl-3-C-trimethylsilylethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil (570 mg, 0.84 mmol) was prepared in Example 1.
The reaction was carried out under the same conditions as in (2). The reaction was completed in 6 minutes. The solvent was distilled off from the reaction solution under reduced pressure, the residue was dissolved in a small amount of methanol, adsorbed on silica gel, the solvent was distilled off again under reduced pressure, and silica gel column chromatography (φ2.7 × 19 + 1. The residue was purified with ethyl / hexane to give the title compound (399 mg, 97%) as a colorless substance.

FAB-MS (LR): m / z 491
(MH ⁺ , 2.1%). FAB-MS (HR): Calcd for C 26 H 23 N
₂ O ₈ : 491.1453. Found: 491.1428. ¹ H-NMR (CDCl ₃ ) δ; 8.22 (brs, 1H, N
H, D ₂ O exchangeable), 8.13 to 7.44 (10
H, Bz), 7.42 (d , 1H, H-6, J 6, Me = 1.
0Hz), 6.43 (d, 1H , H-1 ', J 1', 2 '= 5.7
Hz), 5.72 (d, 1H , H-2 ', J 2', 1 '= 5.7H
z), 4.76 (t, 2H , H-5'ab, J 5 'ab, 4' = 3.
6Hz), 4.50 (t, 1H , H-4 ', J 4', 5 'ab = 3.
6Hz), 3.20 (br s, 1H, 2'-OH, D 2 O ex
changeable), 2.77 (s, 1H, 3'-C-C≡C
H), 1.66 (d, 3H, 5-Me, JMe, 6 = 1.0).
Hz). Anal. _{Calcd for: C 26 H 22 N} 2 O 8. 2H ₂ O: C,
H, 4.60; N, 63.17; H, 4.5.
2; N, 5.52.

(3) 1- (2-deoxy-3,5-di-
O-benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil 1- (3,5-di-O-benzoyl-3-C-ethynyl-β-D-ribo- (Pentofuranosyl) -5-methyluracil (826 mg, 1.68 mmol) was reacted under the same conditions as in Example 1 (3). Thiocarbonylimidazoylation was completed in 31 hours and radical reduction was completed in 7 minutes. In the radical reduction, only benzene was used as a solvent. The reaction solution was treated with a 1N aqueous potassium fluoride solution (50 m
× 3), washed with water (50 mL) and saturated saline (50 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent, and the residue was treated with acetonitrile (100 mL).
mL) and hexane (50 mL), the acetonitrile layer was washed with hexane (50 mL × 4), and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (φ3.5 × 13 cm, 45% ethyl acetate / hexane), partitioned again with acetonitrile (50 mL) and hexane (50 mL), and the acetonitrile layer was washed with hexane (50 mL × 3). The title compound (472 mg, 59
%) As a colorless substance.

FAB-MS (LR): m / z 475
(MH ⁺ , 3.30%). FAB-MS (HR): Calcd for C 26 H 23 N
₂ O ₇ : 475.1504. Found: 475.1475. ¹ H-NMR (CDCl ₃ ) δ; 8.22 (brs, 1H, N
H, D ₂ O exchangeable), 8.16 to 7.45 (10
H, Bz), 7.42 (s, 1H, H-6), 6.42 (d
d, 1H, H-1 ' , J 1', 2 'a = 5.9Hz, J 1', 2 'b =
8.1Hz), 4.90 (dd, 1H , H-5'a, J 5 'a,
4 ′ = 3.6 Hz, J ₅ ′ a, ₅ ′ b = 12.3 Hz), 4.86 (d
d, 1H, H-5'b, J 5 'b, 4' = 4.8Hz, J 5 'b, 5' a
= 12.3 Hz), 4.79 (dd, 1H, H-4 ',
J ₄ ′, ₅ ′ a = 3.6 Hz, J ₄ ′, ₅ ′ b = 4.8 Hz), 3.18
(Dd, 1H, H-2'a , J 2 'a, 1' = 5.9Hz, J 2 'a, 2'
b = 14.4Hz), 2.86 (s, 1H, -CC-C
H), 2.74 (dd, 1H , H-2'b, J 2 'b, 1' = 8.1
Hz, J ₂ 'b, ₂ ' a = 14.4 Hz), 1.69 (s, 3H, 5
-Me). Anal. _{Calcd for: C 26 H 23 N} 2 O 7. 8H ₂ O: C,
63.88; H, 4.89; N, 5.73. Found: C,
63.95; H, 4.76; N, 5.74.

(4) 1- (2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) -5-methyluracil 1- (2-deoxy-3,5-di-O-benzoyl -3
-C-ethynyl-β-D-ribo-pentofuranosyl)-
5-Methyluracil (400 mg, 0.84 mmol) was reacted under the same conditions as in Example 1 (4). The reaction was completed in 6 hours. The reaction solution was neutralized by adding a 1N aqueous hydrochloric acid solution, and the solvent was distilled off under reduced pressure. The residue was dissolved in a small amount of methanol, adsorbed on silica gel, and the solvent was distilled off again under reduced pressure. (20 mL) and chloroform (30 mL), and the aqueous layer was chloroform (30 mL).
× 2), and the solvent was distilled off under reduced pressure to give compound 3 (19).
7 mg, 88%) as a colorless substance.

EI-MS (LR): m / z 266 (M
⁺ , 8.60%). EI-MS (HR): Calcd for C 12 H 14 N 2 O 5:
266.0901. Found: 266.0877. ¹ H-NMR (DMSO-d ₆ ) δ; 11.39 (brs, 1
H, NH, D ₂ O exchangeable), 7.97 (d, 1
H, H-6, JMe, 6 = 1.1 Hz), 6.27 (dd, 1
H, H-1 ', J 1', 2'a = 5.8Hz, J 1 ', 2' b = 8.7
Hz), 6.25 (s, 1H, 3'-OH, D ₂ O exchang
eable), 5.13 (dd, 1H, 5'-OH, JOH, 5 '
a = 4.4 Hz, JOH, 5′b = 4.7 Hz, D ₂ O exchan
geable), 3.95 (dd, 1H , H-4 ', J 4', 5 'a =
3.1 Hz, J ₄ ′, ₅ ′ b = 4.7 Hz), 3.81 (ddd, 1
_{H, H-5'a, J 5} 'a, 4' = 3.1Hz, J 5 'a, OH = 4.
4 Hz, J ₅ 'a, ₅ ' b = 11.8 Hz), 3.77 (dt, 1
_{H, H-5'b, J 5} 'b, 4' = J 5 'b, OH = 4.7Hz,
_{J 5 'b, 5' a} = 11.8Hz), 3.71 (s, 1H, -C-
C≡CH), 2.45 (dd, 1H , H-2'a, J 2 'a,
1 ′ = 5.8 Hz, J ₂ ′ a, ₂ ′ b = 12.9 Hz), 2.39 (d
d, 1H, H-2'b, J 2 'b, 1' = 8.7Hz, J 2 'b, 2' a =
12.9 Hz), 1.87 (d, 3H, 5-Me, JMe, 6
= 1.1 Hz). Anal. _{Calcd for: C 12 H 14 N} 2 O 5: C, 54.1
3; H, 5.30; N, 10.52. Found: C, 54.
00; H, 5.46; N, 10.22.

Example 4 Preparation of 9- (2-deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) adenine (compound 4) (1) 9- (3,5-di-O- Benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) adenine) 9- (2-O-tert-butyldimethylsilyl-3-
C-triisopropylsilylethynyl-β-D-ribo-
Pentofuranosyl) adenine (1.12g, 2.00mmo)
l) was dissolved in acetonitrile (20 mL), and DMAP was added.
(0.54 g, 4.40 mmol), benzoic anhydride (1.00
g, 4.40 mmol) and stirred at 50 ° C. for 60 minutes under an argon atmosphere. Ice was added to the reaction solution, and the mixture was stirred for 60 minutes.
0 mL) and a 0.1N aqueous hydrochloric acid solution (40 mL), and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution (40 mL), water (40 mL x 2), and a saturated saline solution (40 mL), and dried over anhydrous sodium sulfate. Thereafter, this was removed by filtration, the solvent was distilled off under reduced pressure, and the residue was dried at 40 ° C. overnight under reduced pressure. This compound was dissolved in tetrahydrofuran (20 mL), cooled to 0 ° C., and acetic acid (0.30 mL, 5.00 mmol) was added.
l), TBAF / tetrahydrofuran solution (1N, 4.8)
0 mL, 4.80 mmol), and the mixture was stirred for 7 minutes and then at room temperature for 20 minutes. The solvent was distilled off from the reaction solution under reduced pressure,
The residue was subjected to silica gel column chromatography (3.0 ×
Purification with 14 + 2 cm, 3% methanol / chloroform) afforded the title compound (919 mg, 92.3%) as a colorless solid.

¹ H-NMR (DMSO-d ₆ ) δ; 8.4
2,8.16 (each s, each 1H, H-2 & H-
8), 8.15 to 7.62 (m, 10H, Bz), 7.41
(Br s, 2H, NH ₂ , D ₂ O exchangeable), 7.1
6 (s, 1H, 2'- OH, D 2 O exchangeable), 6.
53 (d, 1H, H- 1 ', J 1', 2 '= 6.6Hz), 6.4
4 (d, 1H, H- 2 ', J 2', 1 '= 6.6Hz), 4.91
(Dd, 1H, H-5'a , J 5 'a, 4' = 3.9Hz, J5'a,
5'b = 12.1 Hz), 4.86 (dd, 1H, H-5'b, J
5'b, 4 '= 6.1 Hz, J5'b, 5'a = 12.1 Hz), 4.64
(Dd, 1H, H-4 ', J4', 5'a = 3.9 Hz, J4 ', 5'b
= 6.1 Hz), 3.95 (s, 1H, 3'-CC-C≡C
H).

(2) 6-N, N-dibenzoyl-9-
(3,5-di-O-benzoyl-3-C-ethynyl-2
-O-thiocarbonylimidazolyl-β-D-ribo-pentofuranosyl) adenine 9- [3,5-di-O-benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) adenine] ( 56
0 mg, 1.00 mmol) was suspended in acetonitrile (10.0 ml), and DMAP (0.61 g, 4.90 mmol) and benzoyl chloride (580 μmL) were added thereto.
Stirred for 8 hours. Two ice particles were added to the reaction solution, and the mixture was stirred for 60 minutes. The reaction solution was concentrated twice under reduced pressure, and ethyl acetate (3.
0 mL) and a 0.1N aqueous hydrochloric acid solution (20 mL), and the organic layer was washed with a saturated aqueous sodium hydrogen carbonate solution (30 mL), water (30 mL x 2), and a saturated saline solution (40 mL), and dried over anhydrous sodium sulfate. Thereafter, this was removed by filtration with a cotton plug, the solvent was distilled off under reduced pressure, and the residue was dried at 40 ° C. under reduced pressure overnight. This was dissolved in tetrahydrofuran (6.5 mL), cooled to 0 ° C., and acetic acid (93 μL, 1.56 mmol) was added.
l), TBAF / tetrahydrofuran solution (1.0 N,
(1.40 mL, 4.80 mmol), and the mixture was stirred for 7 minutes and then at room temperature for 20 minutes. The solvent was distilled off from the reaction solution under reduced pressure, dissolved in a small amount of methanol, and adsorbed on silica gel. The solvent was again distilled off under reduced pressure, and the product was subjected to silica gel column chromatography (φ3.0 × 14 + 2c).
m), purified with 50% ether / hexane 50% and dried overnight. This was dissolved in methylene chloride (5.0 mL),
Add 1-thiocarbonyldiimidazole and add 2
Stir for 4 hours. The reaction solution was added to a 0.1 N aqueous hydrochloric acid solution (10 m
L) Saturated aqueous sodium hydrogen carbonate solution (10 mL) water (1
0 mL) and saturated saline (10 mL), and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated and the residue was subjected to silica gel column chromatography (φ1.8 × 14.5,
Purification by 50% ethyl acetate / hexane gave the title compound (269 mg, 59.2%) as a colorless substance.

FAB-MS (LR): m / z 818
(MH ⁺ , 45.8%). FAB-MS (HR): Calcd for C 44 H 32 N 7 O 8
S: 818.2032.1017. Found: 818.2
044. _{^{1 H-NMR (CDCl 3)}} δ; 8.61 (s, 1H, H-
8), 8.58 (s, 1H, H-2), 8.14 to 7.26
(22H, Bz, Im), 6.91 (s, 1H, Im), 6.
84 (d, 1H, H-1 ', J1', 2 '= 3.8 Hz), 6.5
9 (d, 1H, H-2 ', J2', 1 '= 3.8 Hz), 5.03
(Dd, 1H, H-5'a, J5'a, 4, '= 3.6 Hz, J5'a,
5'b '= 11.7Hz), 4.98 (dd, 1H, H-4', J
4 ', 5a,' = 3.6 Hz, J4 ', 5'b' = 5.7 Hz), 4.93
(Dd, 1H, H-5'b, J5'b, 4, '= 5.7 Hz, J5'b,
5′a = 11.7 Hz), 2.98 (1H, 3-C—C≡C)
H). Anal. _{Calcd for C 44 H 31 N 7} O 8 S · 0.2AcOE
t: C, 64.30; H, 3.94; N, 11.79. F
sound: C, 64.59; H, 4.22; N, 11.58.

(3) 6-N, N-dibenzoyl-9-
(2-Deoxy-3,5-di-O-benzoyl-3-C
-Ethynyl-β-D-ribo-pentofuranosyl) adenine 6-N-dibenzoyl-9- (3,5-di-O-benzoyl-3-C-ethynyl-2-O-thiocarbonylimidazolyl-β-D -Ribo-pentofuranosyl) adenine (220 mg, 0.27 mmol) was azeotroped with toluene (X2)
Then, it was dissolved in benzene (27 mL, argon gas was bubbled for 30 minutes), heated under reflux in an argon atmosphere, and tributyltin hydride (87 µm) was added thereto.
L, 0.32 mmol) and AIBN (13 mg, 0.08 mmol)
Was added and heated under reflux for 20 minutes. The reaction solution was cooled on ice and returned to room temperature, and the solvent was distilled off under reduced pressure. The residue was extracted with acetonitrile (20 mL),
Washed with hexane (30 mL × 3). This was concentrated under reduced pressure, the residue was dissolved in a small amount of chloroform, adsorbed on silica gel, the solvent was again distilled off under reduced pressure, and the residue was subjected to silica gel column chromatography (φ1.8 × 13 + 0.1.
Purification was performed using 5 cm, 40% ethyl acetate / hexane to give the title compound (96 mg, 51.6%) as a colorless substance.

FAB-MS (LR): m / z 692
(MH +, 5.1%). FAB-MS (HR): Calcd for C 40 H 30 N
₅ O _7: 692.143. Found: 692.2719. _{^{1 H-NMR (CDCl 3)}} δ; 8.61 (s, 1H, H-
8), 8.40 (s, 1H, H-2), 8.04 to 7.34
(20H, Bz), 6.59 ( dd, 1H, H-1 ', J 1',
_{2 'a = 7.4Hz, J 1} ', 2'b = 6.4Hz), 4.94 (dd,
_{1H, H-5'a, J 5} 'a, 4' = 3.0Hz, J5'a, 5b '= 1
0.9 Hz), 4.91 (dd, 1H, H-4 ', J4', 5'a,
= 3.0 Hz, J4 ', 5'b = 5.6 Hz), 4.87 (dd, 1
H, H-5'b, J5'b, 4, '= 5.6 Hz, J5'b, 5'a = 1
0.9Hz), 3.51 (dd, 1H, H-2'a, J2'a, 1, '
= 7.4 Hz, J2'a, 2'b = 14.3 Hz), 3.33 (dd,
1H, H-2'b, J2'b, 1, '= 6.4 Hz, J2'b, 2'a = 1
4.3 Hz), 2.85 (s, 1H, 3-CC-CH). Anal. _{Calcd for C 40 H 29 N 5} O 7 · 0.7H 2 O:
C, 68.21; H, 4.35; N, 9.94. Found:
C, 68.46; H, 4.46; N, 9.62.

(4) 9- (2-Deoxy-3-C-ethynyl-β-D-ribo-pentofuranosyl) adenine 6-N, N-dibenzoyl-9- (2-deoxy-3,5
-Di-O-benzoyl-3-C-ethynyl-β-D-ribo-pentofuranosyl) adenine (55 mg, 0.08 mmol)
l) was dissolved in methanol (1.6 mL), and a 5N sodium methylate / methanol solution (20 μL, 0.1 mmol) was added.
l) was added, and the mixture was stirred at room temperature for 11.5 hours under an argon atmosphere. The reaction solution was neutralized by adding a 1N aqueous hydrochloric acid solution, the solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (φ0.9 × 7.5 + 1 cm, 12% methanol / chloroform) to give compound 4 ( 25mg, quan
t) was obtained as a colorless solid.

Mp: 118-120 ° C. EI-MS (LR): m / z 275 (M ⁺ , 4.6
%). EI-MS (HR): Calcd for C 12 H 13 N 5 O 3:
275.1017. Found: 275.1028. _{^{1 H-NMR (D 2 O}} ) δ; 8.56 (s, 1H, H-
8), 8.43 (s, 1H, H-2), 6.54 (t like
dd, 1H, H-1 ', J1', 2'a = 7.5 Hz, J1 ', 2'b
= 5.8 Hz), 4.24 (br.s, 1H, H-4 '), 4.
01 (dd, 1H, H-5'a, J5'a, 5'b '= 12.5H
z), 3.95 (d, 1H, H-5'b, J5b ', 5'a, = 12.
5Hz), 3.18 (s, 1H, 3-CC = CH), 3.
09 (dd, 1H, H-2'a, J2'a, 1, '= 7.45 Hz,
J2'a, 2'b = 13.2 Hz), 2.89 (dd, 1H, H-
2′b, J2′b, 1, ′ = 5.8 Hz, J2′b, 2′a = 13.2 Hz) ¹³ C-NMR (MeOH-d ₄ ) δ: 157.50 (C), 153.53 (C), 141.
70 (C), 126.80 (C), 120.50 (C),
90.92 (CH), 86.23 (CH), 83.11
(CH), 76.57 (C), 74.37 (C), 63.
77 (CH), 47.13 (CH)

Pharmacological Test Example 1 (Cell Killing Activity) Human KB cells and L1210 cells were cultured at 1 × 10 ⁵ cells / well.
And seeded in a 96-well plate. After the compound of the present invention was dissolved in purified water, it was diluted to various concentrations with RPMI 1640 medium, added to each well, and cultured. After contacting at 37 ° C. for 3 days in a 5% CO ₂ incubator, the number of cells was counted by the MTT method. Drug concentration (IC ₅₀ ) that reduces the cell number of control by 50% in the cell killing effect of each compound
Expressed as Table 1 shows the results.

[0075]

[Table 1]

As is apparent from the results, the compound of the present invention exhibited extremely strong cell killing activity.

[0077]

The novel 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative of the present invention has, for example, an excellent antitumor activity and is useful as an antitumor agent.

Claims (7)

[Claims] 1. 2-deoxy- represented by the general formula (1)
A 3-ethynyl-β-D-ribofuranosyl derivative and an easily eliminable ester thereof in a living body, or a pharmaceutically acceptable salt thereof. Embedded image (In the formula, B represents a nucleobase that may have a substituent.) 2. B is cytosine, uracil, thymine, adenine, guanine, 5-fluorocytosine, 5-fluorouracil, 5-bromocytosine, 5-bromouracil,
2. The 2-deoxy-3-ethynyl-.beta.-D-ribofuranosyl derivative according to claim 1, which is 4-N-methylcytosine or 4-N, N-dimethylcytosine; Acceptable salts. 3. The 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative according to claim 2, wherein B is cytosine, uracil, thymine, or adenine, or an ester thereof easily removable in vivo, or a pharmaceutically acceptable salt thereof. Acceptable salts. 4. The method according to claim 1, wherein the ester-forming residue which can be easily eliminated in vivo is an acyl group.
An ester of a deoxy-3-ethynyl-β-D-ribofuranosyl derivative which can be easily eliminated in vivo, or a pharmaceutically acceptable salt thereof. 5. The 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative according to any one of claims 1 to 4,
A medicament comprising, as an active ingredient, an ester which can be easily eliminated in a living body or a pharmaceutically acceptable salt thereof. 6. The 2-deoxy-3-ethynyl-β-D-ribofuranosyl derivative according to any one of claims 1 to 4,
A pharmaceutical composition comprising an ester or a pharmaceutically acceptable salt thereof easily removable in vivo and a pharmaceutical carrier. 7. The medicament according to claim 5, which is an antitumor agent.