JPH01197497A - Production of 2'-alkylidenecytidine derivative - Google Patents

Abstract

PURPOSE:To obtain the title compound in high yield, by subjecting a specific cytidine derivative to alkylidenating reaction using a Wittig reagent and deprotecting the resultant product after the reaction. CONSTITUTION:A cytidine derivative expressed by formula I (R<1> is H, halogen or lower alkyl; R<3> is acyl-protecting group; R<4> is OHprotecting group) as a raw material compound is subjected to alkylidenating reaction using a Wittig reagent [preferably a compound expressed by the formula (C6H5)P=CH-R<2> (R<2> is H or lower alkyl]. After the reaction, the resultant product is preferably treated with a strong alkali and the protecting groups expressed by the groups R<3> and R<4> are removed to afford the aimed compound expressed by formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing 2'-alkylidene cytidine derivatives from cytidine derivatives.

[Conventional technology]

2'-Alkylidenepyrimidine nucleoside is a new compound developed by the present inventors, and is expected to be developed as an antitumor or antiviral agent (
(See Japanese Patent Application No. 62-65405).

The preparation of the 127-alkylidenecytidine derivative described in Japanese Patent Application No. 62-65405 uses a uridine derivative as a raw material compound, and
The process consisted of the following reaction steps: alkylideneation reaction at the 4-position of the sugar moiety, (2) removal reaction of the protective groups protecting the hydroxyl groups at the 3- and 51st-positions of the sugar moiety, and (2) amination reaction of the 4-position of the base moiety.

[Problem to be solved by the invention]

However, the above-mentioned conventional method has problems in that the preparation process is long and the isolation yield of the final product is low.

[Means to solve the problem]

The present inventors tried to prepare 2'-alkylidene cytidine derivatives using various compounds, and as a result, they obtained the general formula [II] [wherein R1 is a hydrogen atom, a halogen atom or a lower alkyl group, and R3 is an acyl group] , R4 represents a hydroxyl group-protecting group] is used as a raw material compound, 2
The present invention was completed by discovering that '-alkylidene cytidine derivatives can be obtained in good yield.

That is, 1 the present invention provides a method for producing a 2'-alkylidene cytidine derivative represented by the general formula (1) [wherein R1 has the same meaning as above and R2 represents a hydrogen atom or a lower alkyl group], The above general formula [
The raw material compound represented by II) is subjected to an alkylidene reaction using a Wittig reagent, and after the reaction, the protecting groups represented by R3 and R4 are removed to obtain 2'-alkylidene cytidine represented by the above general formula (1). This invention relates to a method for producing a derivative (hereinafter abbreviated as the method of the present invention).

The present invention will be explained in detail below.

The raw material compound used in the method of the present invention has the general formula (II
) (Hereinafter, it may be abbreviated as the present raw material compound.) In the formula, examples of the halogen atom for R1 include iodine, bromine, chlorine, and fluorine atoms. Examples of lower alkyl groups for R1 and R2 include alkyl groups having 1 to 3 carbon atoms such as methyl, ethyl, propyl, and isopropyl. Examples of the acyl group for R3 include acetyl, chloroacetyl, dichloroacetyl, trichloroacetyl, trifluoroacetyl, methoxyacetyl, propionyl, n-butyryl, isobutyryl, (E)-2-methyl-2-butenoyl, pentanoyl, pivaloyl, etc. Aliphatic acyl group, benzoyl, o-(dibromomethyl)benzoyl, p-phenylbenzoyl, 2,4.6-trimethylbenzoyl, p
-Toluoyl, p-anisoyl, p-halobenzoyl,
Examples include aromatic acyl groups such as p-nitrobenzoyl and p-methoxybenzoyl.

The protecting group for R4 may be one commonly used as a protecting group for hydroxyl groups, such as acetyl, propionyl,
Acyl groups such as butyryl, benzoyl, naphthoyl, acetal or ketal type protecting groups such as ethylidene, propylidene, isopropylidene, benzylidene, cyclohexylidene, cyclopentylidene, methoxymethylidene, ethoxymethylidene, dimethoxymethylidene, benzyl, P -Aralkyl groups such as methoxybenzyl, 3,4-dimethoxybenzyl, diphenylmethyl, triphenylmethyl, α- or β-naphthylmethyl, α-naphthyldiphenylmethyl, trimethylsilyl, t-butyldimethylsilyl, methyldiisopropylsilyl, triisopropyl Examples include silyl groups such as silyl and tetraisopropyldisiloxyl.

Such a raw material compound can be obtained by, for example, introducing a protecting group into the amino group of the base moiety and the 3- and 5-position hydroxyl groups of the sugar moiety of a cytidine derivative, and then subjecting the 2-position hydroxyl group of the sugar moiety to an oxidation reaction. It can be prepared. The reaction process is shown in the following reaction formula.

[In the formula, R1, R3, and R4 have the same meanings as above. [Introduction of protecting groups represented by R3 and R4 into the cytidine derivative is as follows:
This may be carried out according to a method commonly used for the protecting group used. For example, the introduction of the acyl group represented by R3 is carried out in an amount of 1 to 5 times the mole of the acylating agent (
Acid anhydride or acid chloride of the acid corresponding to R7') is used as a reaction solvent (for example, pyridine, picoline, diethylaniline, dimethylaminopyridine, dimethylformamide, acetonitrile, tetrabutylamine, triethylamine, etc. alone or in combination) In the reaction temperature O~
This can be carried out by reacting at 50°C for 1 to 30 hours. In addition, the introduction of a protecting group for the hydroxyl group represented by R4 can be explained using a silyl protecting group as an example, using a silylating agent in an amount of 1 to 3 times the mole of the cytidine derivative in the same way as acylation. It can be carried out by reacting under the following reaction conditions.

Next, the cytidine derivative (compound (A)) having a protecting group thus prepared is subjected to an oxidation reaction to obtain the present raw material compound.

Methods for oxidizing the 2'-position hydroxyl group of compound (A) include chromic acid oxidation (method A) using a chromic acid-pyridine-acetic anhydride complex, or activated dimethyl sulfoxide oxidation produced by oxalyl chloride-dimethyl sulfoxide. (Method B) can be used. The oxidation reaction is carried out using A in the presence of an oxidizing agent in an amount of 1 to 10 times the mole of the compound.
In the case of method B, the temperature is 0℃ to room temperature, and in the case of method B, the temperature is -10 to
This can be carried out by reacting at -80°C for 1 to 10 hours.

The raw material compound prepared in this manner is isolated and purified by appropriately combining the usual isolation and purification methods for nucleosides (for example, various chromatography methods such as ion exchange and adsorption, recrystallization method, etc.). can do.

In the method of the present invention, for example, the raw material compound prepared as described above is subjected to an alkylidene reaction using a Wittig reagent, and after the reaction, protecting groups represented by R'' and R4 are removed to obtain a 2'-alkylidene cytidine derivative. get 2'
- A method for producing an alkylidene cytidine derivative.

The Witti-Nich reagent that can be used in the method of the present invention has the general formula (c G Hl, )□P = C
It is an alkylidenephosphorane represented by the H- side (F?, 2, where - has the same meaning as above), and specific examples include triphenylphosphine methylene, triphenylphosphine ethylene, triphenylphosphine propylene, etc. can do.

The Wittig reagent used in the reaction is prepared by using the general formula ((CsHs)aP''-CHz171)X-R1 ((CsHs)aP''-CHz171)X-R1 (wherein has the same meaning as above, and X- represents a halogen ion such as Br- or Do). ) (e.g. methyltriphenylphosphonium bromide, methyltriphenylphosphonium iodide, ethyltriphenylphosphonium bromide, etc.) and strong alkalis (
For example, potassium hydride, sodium hydride, n-butyllithium, sodium methoxide, potassium t-
butoxide, sodium amide, etc.) according to a conventional method. The amount of Wittig reagent to be used can be appropriately selected from 1 to 3 moles per mole of the raw material compound.

Such an alkylidene reaction using a Wittig reagent is carried out by combining the present raw material compound and the Wittig reagent in a solvent (for example, tetrahydrofuran, dioxane, ether, benzene, dimethyl sulfoxide, etc. alone or in a mixed solvent) at a reaction temperature of -30 to 30°C. This can be carried out by reacting for 5 to 20 hours.

In addition, in the above alkylidene reaction, a phosphonium salt of the Witteitz intermediate, which is a reaction intermediate, is present in the reaction solution [although the structure of the intermediate is not clear, it is thought to have the structure shown below based on the reaction mode. It will be done.

(In the formula, R1, R'', R'', R' and X have the same meanings as above.

)] remains, if necessary, add the above intermediate to a strong alkali (e.g., potassium hydride, hydrogen 2′ with a protecting group
- It may be recovered as an alkylidene cytidine derivative.

The 2'-alkylidene cytidine derivative having a protecting group thus prepared may be isolated and purified, if necessary, by the same isolation and purification means as used for the above-mentioned raw material compound, and then subjected to a reaction for removing the protecting group.

Removal of the protecting group can be carried out by appropriately selecting a removal method commonly used for the protecting group used. For example, the acyl group of R3 can be removed by an alkaline hydrolysis method using methanol-ammonia (1:1), concentrated ammonia, etc. When a silyl group is used as a protecting group for the hydroxyl group of R4, fluorine The silyl group conductor can be isolated by ammonium treatment, acidic or alkaline hydrolysis, and the silyl group conductor can be isolated by the usual means of isolation and purification of nucleosides (various chromatographic methods such as adsorption or ion exchange,
Isolation and purification can be carried out by appropriately combining methods (such as recrystallization method).

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples and Reference Examples.

Reference example 3',5'-0-(tetraisopropylsiloxane-1,3-diyl)-2'-keto-4-N-benzoylcytidine 1) 3',5'-〇-(tetraisopropyldisiloxane) -1,3-diyl)-4-N-benzoylcytidine synthesis 4-N-benzoylcytidine 5g (20.6mmol
) was dissolved in pyridine 50-, and 1°1.3.3
-dichlorotetraisopropyldisiloxane 7,1nn
(22.6 mmol) was added, and the mixture was stirred and reacted at 0° C. for 3 hours and then at room temperature for 3 hours. After the reaction, ice water was added to the reaction solution, and the solvent was distilled off under reduced pressure. The resulting residue was dissolved in ethyl acetate, and the solution was partitioned three times with water. After drying the organic layer over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure. The residue was adsorbed onto a silica gel column (5×10 am) and
Elution with a mixed solvent of 3% ethyl acetate-hexane gave a fraction of the target compound, which was concentrated under reduced pressure to give 3'.

5'-〇-(tetraisopropyldisiloxane-1,3
7.3 g (yield: 86%) of amorphous powder of -diyl')-4-N-benzoylcytidine was obtained.

Elemental analysis: C,5H43N30. S i ”H2
Calculated value as 0 C: 55.32%, H: 7.46%
, N: 6.91% Sword 1 Lii Direct C: 55.54%, H
Near, 41%, N: 6. 99%2)3',
5'-0-(tetraisopropyldisiloxane-1,
Synthesis of 3-diylcine-2'-keto 4-N-benzoylcytidine Chromium dioxide (Cry) 5 g (40 mmol)
, pyridine 8,3 mfl (80 mmol) and anhydrous acid Wll 5 rnQ (40 mn+ol) were mixed and dissolved in 110 mQ of methylene chloride to obtain a chromic acid complex solution. To this, 3',5'-〇-(tetraisopropyldisiloxane-1,3-diyl)-4-N
-benzoylcytidine 5.9 g (10mff1ol
) was dissolved and reacted with stirring at room temperature for 1 hour. After the reaction, 500 mQ of ethyl acetate was added dropwise to the reaction solution, and the solution was passed through a silica gel column (6×1.5 C!l) to obtain a filtrate.

The collected filtrate was dried under reduced pressure, and the residue was adsorbed on a silica gel column (3,0 x 21 countries) and 25% ethyl acetate-
It was eluted with a mixed solvent of hexane and crystallized from ethyl acetate-hexane to give 3',5'-〇-(tetraisopropyldisiloxane-1,3-diyl)-2'-keto-4-
4.6 g (yield 78%) of N-benzoylcytidine was obtained.

Melting point: 135-137°C Elemental analysis: Calculated value as Cza H4x N□○, Si, C: 57.21%, H near, 03%, N near,
15%1 value C: 57.08%, H near, 12%
, Nia, 01% Example 12'-deoxy-2'-
Production of methylidenecytidine hydrochloride 1) Synthetic odor of 3',5'-〇-(tetraisopropyldisiloxane-1,3-diyl)-2'-deoxy-2'-methylidene-4-N-benzoylcytidine 10.7g (3
0 n + mol) was suspended in 60 mQ of tetrahydrofuran, cooled to -20"C, and 15.8 d (25 mmol) of n-butyllithium test solution was added dropwise thereto, and the reaction was stirred for 1 hour. To this solution, 3' was suspended in 20 mQ of tetrahydrofuran. A solution of 2.9 g (5 mmol) of 5'-0-(tetraisopropyldisiloxane-1,3-diyl)-2'-keto-4-N-benzoylcytidine was added dropwise at -20°C. After reacting for an hour, the temperature was returned to room temperature and the reaction was stirred for an additional 2 hours.After the reaction, 1
A specified aqueous ammonium bromide solution of 50 mΩ was added, and the mixture was further partitioned with ethyl acetate. After the distribution, the organic layer was washed twice with water and dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure.
1) and eluted with a mixed solvent of 25% ethyl acetate-hexane to obtain 3',5'-0-(tetraisopropyldisiloxane-1,3-diyl)-2'-deoxy-
0.9 g of amorphous powder of 2'-methylidene-4-N-benzoylcytidine was obtained.

Furthermore, both fractions eluted with 6.25% ethanol-dichloromethane in the above silica gel column were collected and concentrated to dryness, the resulting residue was dissolved in 35 nQ of tetrahydrofuran, and 6.1 g of a 60% powder reagent of sodium hydride was added under an argon stream. After addition, the mixture was stirred at room temperature for 3 hours. To this, add ammonium bromide aqueous solution in the same manner as above, and add ethyl acetate.
After partitioning with water and further purifying with a silica gel column, the 3′
.

5'-〇-(tetraisopropyldisiloxane-1,3
-diyl)-2'-deoxy-2'-methylidene-4-
N-benzoylcytidine 1.2g (total 2.1g, yield 7
2%) of amorphous powder was obtained.

Elemental analysis: Calculated value as C,, H4, N30GSx2 C,: 59.46%, H near, 40%, N near, 17
% phase growth C: 59.39%, H near, 52%, N near, 1
0%2) 2'-deoxy-2'-methylidene-4-N-
Synthesis of benzoylcytidine 3',5'-0-(tetraisopropyldisiloxane-1,3-diyl)-21-deoxy-2'-methylidene-4-N-benzoylcytidine 343 (1 mmol)
) was dissolved in 10 mQ of tetrahydrofuran, and 1
After adding 2.2 mfl of the specified tributylammonium fluoride and stirring the reaction at 0°C for 30 minutes, the reaction solution was neutralized with acetic acid, the solvent was distilled off under reduced pressure, and the resulting residue was transferred to a silica gel column (1,6X30C! 2'-deoxy-2'-methylidene-
302 ml of 4-N-benzoylcytidine (yield 88%) was obtained.

Melting point: 300℃ or higher Elemental analysis: Calculated value as C, Hl, N, ○, C: 5
9.47%, H: 4.99%, N: 12.24% Actual value C: 59.28%, H: 5.05%, N: 12.
11% 3) Synthesis of 2'-deoxy-2'-methylidenecytidine hydrochloride Dissolve 139 mg (0.5n+mol) of 2'-deoxy-2'-methylidene-4-N-benzoylcytidine in methanolic ammonia 10- After stirring and reacting at room temperature for 6 hours, the solvent was distilled off under reduced pressure.

The residue was developed with a silica gel column (1,6 x 10ao, elution solvent = 20% ethanol-chloroform) to collect the target compound fraction, to which 2 mQ of 1N hydrochloric acid was added, the solvent was distilled off under reduced pressure, and the residue was dissolved in acetone-chloroform. Crystallized from methanol to give 2'-deoxy-2'-methylidenecytidine 11
5■ (yield 83%) was obtained.

〔Effect of the invention〕

The method of the present invention is characterized by using a specific cytidine derivative as a raw material compound, and has the following advantages compared to the conventional method using a uridine derivative as a raw material compound.

(2) The raw material compound to be subjected to the alkylidene reaction of the method of the present invention can be prepared in a shorter reaction step than in the conventional method.

(2) The method of the present invention consists of two steps: an alkylidene reaction and a protecting group removal reaction, and the amination reaction employed in conventional methods can be omitted.

(2) By omitting the reaction steps as described in (2) and (2), the synthesis yield of the final product can be improved. Specifically, the overall synthesis yield of a 2'-alkylidene cytidine derivative from a 2'-ketocytidine derivative, which is a raw material compound, is 53% in the method of the present invention, whereas it is 25% in the conventional method.
%, and the method of the present invention makes it possible to improve the synthesis yield by more than twice that of the conventional method.

Claims (1)

[Claims] 1) General formula [I] ▲ Numerical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, R^1 is a hydrogen atom, a halogen atom, or a lower alkyl group, and R^2 is a hydrogen atom or a lower alkyl group. ] A method for producing 2'-alkylidene cytidine derivatives represented by the general formula [II] ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [II] [In the formula, R^1 has the same meaning as above, R ^3 represents an acyl protecting group, and R^4 represents a hydroxyl protecting group. ] The raw material compound represented by is subjected to an alkylidene reaction using Wittig reagent, and after the reaction, the protecting groups represented by R^3 and R^4 are removed to obtain 2 represented by the above general formula [I]. A method for producing a 2'-alkylidene cytidine derivative, which comprises obtaining a 2'-alkylidene cytidine derivative. 2) The Wittig reagent has the general formula [III] (C_6H_5)_3P=CH-R^2 [wherein R^2 represents a hydrogen atom or a lower alkyl group]. ] The method for producing a 2'-alkylidene cytidine derivative according to claim 1, which is represented by the following formula. 3) The method for producing a 2'-alkylidene cytidine derivative according to claim 1, wherein a strong alkali treatment is further performed between the alkylidene reaction using a Wittig reagent and the reaction for removing the protecting groups represented by R^3 and R^4. .