KR100957756B1 - Process for preparing of 2'-deoxy-2'2'-difluorocytidine - Google Patents

Abstract

The present invention is to prepare an optically pure 3R- hydroxypropane amide compound of the formula [8] from which the optically pure D-erythro-2,2-difluoro- of the formula [5] and [Formula 3] A 2-deoxy-1-oxoribose compound was prepared and glycosylated with a nucleobase to be β-nucleoside. The 2'-deoxy-2 ', 2'-difluorosa of [Formula 1] It relates to a process for preparing ittidine. The optically pure compound of the following Chemical Formula 1 can be prepared by the present invention in high purity and high yield.

[Formula 1]

(3)

[Chemical Formula 5]

[Formula 8]

Wherein R ₁ and R ₂ are each independently a protecting group as benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, 4 -t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group, R ₃ and R ₄ are each independently C ₁ to C ₃ alkyl, R ₅ is a methyl or ethyl group, R ₆ is hydrogen, methyl or methoxy to be.

Description

Process for preparing 2'-deoxy-2 ', 2'-difluorocytidine {Process for preparing of 2'-deoxy-2'2'-difluorocytidine}

The present invention relates to a method for preparing 2'-deoxy-2 ', 2'-difluorocytidine of the following [Formula 1].

[Formula 1]

Gemcitabine (gemcitabine) of [Formula 1] is a nucleoside structurally having a ribofuranose skeleton, and stereochemically, cytosine (cytosine), which is a nucleobase (nucleobase) at 1-position of ribofuranose, is 2'-deoxy-2 ', 2'-difluoronucleoside compound oriented in the β-position, as well as pancreatic cancer, bladder cancer, breast cancer or ovarian cancer, as well as Non Small Cell Lung Cancer (NSCLC) It is a widely used anticancer agent to treat.

In order to prepare gemcitabine, a D-erythro-1-oxo ribose compound as shown in [Formula 5] having a D-erythro structure having a structure in which a hydroxyl group at position 3 or a hydroxyl group introduced with a protecting group is oriented downward is used. It is very important to develop a method for synthesizing effectively.

[Chemical Formula 5]

Wherein R ₁ and R ₂ are each independently a protecting group as benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, 4 -t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group.

Looking at a known method for preparing a 1-oxo ribose compound having a D-erythro structure, US Pat. No. 4,526,988 discloses 3R-hydroxy enantiomer (1) and 3S-hydroxy enantiomer (2). 2,2-difluoro-3-hydroxy-3- (2,2-dialkyldioxoran-4-yl) propanoic acid alkyl ester containing) in a ratio of about 3 to 1 by column chromatography The separation method is described.

Wherein R ₈ and R ₉ are each independently C ₁ to C ₃ alkyl.

Among them, the 3R-hydroxy enantiomer (1) is reacted with a strong acid, and as shown in the following Scheme 1, the dioxolane group serving as a protecting group is hydrolyzed, and the lactonation reaction proceeds so that the 3-hydroxy group is oriented downward. A 2,2-difluoro-2-deoxy-D-erythro-1-oxoribose (3) compound having an erythro structure is produced.

The column chromatography method used in the above method is not suitable for large scale production due to the limited size of the column and the amount of material to be loaded. In particular, silica gel, which is a column filler, is expensive, and a considerable amount of developing solvent must be used. Therefore, the cost of separation is high.

Meanwhile, US Pat. Nos. 4,965,374, 5,223,608 and 5,434,254 disclose 3-benzoyloxypropionate esters (3R- and 3S- in a 3 to 1 mixed state as shown in Scheme 2 below). ) And hydrolyzed by acid, and then azeotropically distilled water to minimize reverse reaction with precursor to prepare lactone ring (5) with erythro and treo mixed, and protect 5-hydroxy group with benzoyl 3,5-dibenzoyloxy compound (6) was prepared, and then cooled and cooled to a low temperature of -5 ° C to 10 ° C in dichloromethane to separate and obtain only the desired erythro enantiomer (7) from the erythro and threo mixtures as a precipitate. How to do this is described.

In the above formula, Bz means benzoyl group.

This method is characterized in that the 3-benzoyl oxypropionate ester (3) mixed with 3R- and 3S- is used for the lactone ring reaction without separation, particularly 3,5 in a state where erythro and treo are mixed. Only by dissolving the dibenzyl-1-oxo ribose compound (6) in a solvent and lowering the temperature to low temperature, it is possible to easily separate and obtain only 3,5-dibenzoyl enantiomer (7) having a desired erythro structure. It can be characterized. However, this method is very corrosive as the acid used for the lactone ring reaction, and uses an excess of 3 equivalents or more of trifluoroacetic acid, an expensive and highly toxic reagent, and especially 3-benzoyl oxypropionate ester (4) as a starting material. As a result, the overall reaction yield of obtaining 3,5-dibenzoyl enantiomer (7) is very low such that it is only about 25%.

Korean Patent Application No. 10-2004-0057711 discloses a 3R-enantiomer (10) as an optically pure salt by introducing a stericly large protecting group into the hydroxyl group (9), followed by treatment with a base to obtain a 3R-enantiomer (10). A method of obtaining an enantiomer (11) having a D-erythro structure by being subjected to a toning reaction is shown in the following Scheme 3.

Wherein R ₁₀ , R ₁₁ and R ₁₂ are C ₁ to C ₃ alkyl groups, R ₁₃ is a phenyl group or a phenyl group with a substituent, and M is NH ₃ , Na or K.

According to the above method, biphenyl-4-carbonyl chloride, which is a compound used as a protecting group, has a disadvantage in that the unit cost is higher than that of a benzoyl or naphthoyl compound, which is generally used as a protecting group, wherein 3R-carboxylic acid ester enantio Although the separation of the mers is possible, it is not possible to obtain 3S-carboxylic acid ester enantiomers.

As described above, the conventionally known method mainly uses 3R-hydroxy enantiomer, which is a precursor, to synthesize 1-oxoribose compound having an erythro structure by hydrolyzing 3R-hydroxy group enantiomer. It is not suitable for mass production methods because it is obtained by separation through chromatography or by introducing expensive protecting groups, and it is difficult to obtain 3R- and 3S-hydroxy compounds selectively, and even though 3R- and 3S-hydroxy compounds Even if the lactonation reaction is completed in the state of the mixed mixture, the erythro and threo enantiomers are mixed, so that only the erythro enantiomer is selectively separated from the 1-oxo ribose mixture. have.

The 2'-deoxy-2 ', 2'-difluorocytidine of [Formula 1] converts the lactone compound (12) to the keto moiety of the lactone in the usual manner as shown in Scheme 4 below. Thus, the lactol compound (13) was obtained, and since the 1-hydroxy group of the lactol compound was difficult to chemically directly glycosylation reaction with the nucleobase, the ribofuranose intermediate (14) having a highly reactive leaving group introduced therein was obtained. After conversion, activated ribofuranose intermediates can be prepared by reacting with nucleobases to obtain nucleosides followed by deprotection.

Wherein P and P ₁ are each a hydroxy protecting group and L is a leaving group.

In this case, P and P1, which are hydroxy protecting groups of Compound (12), use the same protecting group in most methods except Korean Patent Application No. 10-2004-0057711, and Korean Patent Application No. 10-2004-0057711 also uses 3 times. The protecting group at the position has always shown a limit which is limited to the 4-phenyl-benzoyl group.

As the leaving group, a sulfonyloxy leaving group and a halo leaving group are known, and α-methanesulfonyloxy ribofuranose, which is a kind of sulfonyloxy leaving group, is known to be most preferable.

The glycosylation reaction of Scheme 5 proceeds by the S _N 2 reaction mechanism where the nucleobases attack and replace the leaving group at the 1-position of D-erythro-ribofuranose, so that the cytosine base of gemcitabine is β- In order to produce high yields of nucleosides oriented in position, it is important to obtain, in high purity, an α-anomer in which the leaving group is oriented in the α-position.

Generally, in reactions in which nucleobases attack and replace the 1-position leaving group of D-erythro-ribofuranose, the leaving group after the reaction leaves the 1-position by attacking the 1-position competitively with the nucleobase. Anomerization is induced at, resulting in a different α-anomer to β-anomer ratio than the initial reaction. That is, even if the glycosylation reaction is carried out using only the α-anomer, the amount of β-anomer increases with time, and the reaction proceeds nonsteroselectively so that the nucleobase is moved to the β-position. Not only the desired β-nucleosides oriented but also α-nucleosides are produced together as impurities.

If the leaving group is sulfonyloxy, such anomerization occurs less so that a pure α-sulfonyloxy anomer such as α-methanesulfonyloxy compound can be used to obtain an excess of the desired β-nucleoside.

On the other hand, when the leaving group is halo, even when pure α-halo anomer is used in the glycosylation reaction, the degree of anomerization by the free halide after the reaction is relatively large, and the β-halo anomer increases as the reaction proceeds. do. In particular, the β-halo anomer has a faster glycosylation reaction than the α-halo anomer, and since the halo leaving group is less reactive than a sulfonyloxy leaving group, the reaction time is longer and a higher reaction temperature is required. -Inferior stereoselectivity with increased nucleosides.

Eventually, in the reaction for preparing 2'-deoxy-2 ', 2'-difluoro nucleoside through glycosylation reaction, the method using 1-halo-ribofuranose is α-methanesulfonyloxylai. It is bound to stereoselectivity compared to bofuranose, and for that reason, the method through α-methanesulfonyloxyribofuranose is known to be the best method among the previously developed glycosylation methods.

More specifically, first, as a method of glycosylating with nucleobases using α-sulfonyloxyribofuranose, U.S. Patent Nos. 5,371,210, 5,401,838, 5,426,183, 5,594,124, and 5,606,048 And European Patent No. 577,303 disclose a high proportion of β-nucleosides (16) by reacting α-anomer-rich 1-sulfonyloxy ribofuranose derivatives (15) with nucleobases, as shown in Scheme 5 below. Processes for the stereoselective glycosylation produced by are known.

Wherein P, P ₁ are hydroxy protecting groups, W is an amino protecting group or hydrogen, L is a leaving group substituted with sulfonyloxy, substituted arylsulfonyloxy, such as nitrile, halo, carboalkoxy or nitro, etc. to be.

According to this method, α-nucleosides (17) in which the β-nucleosides (16) in which nucleobases are mainly oriented in the β-position are reversed by good reactivity and low anomerization of the 1-sulfonyloxy leaving group. It is produced in an excess of 5 to 7 times compared to that, and as a result, gemcitabine can be obtained in a high yield of 30 to 75%.

Meanwhile, U.S. Patent Nos. 4,526,988, 5,453,499 and Korean Patent Application No. 10-2005-0041278 disclose 1-α-halo-ribofuranose derivatives incorporating halo leaving groups.

US Pat. No. 4,526,988 discloses 1-acetate derivatives by reacting the 1-hydroxy group of the lactol compound (13) with acetic anhydride or another source of acetyl group in the presence of at least one equivalent of acid scavenger, as shown in Scheme 6 above. ), Followed by the slow addition of hydrogen bromide or hydrogen chloride gas at a low temperature of about -50 to 0 ° C to prepare 1-halo anomer (19). However, this method has a problem in that the yield of α-halo anomer obtained due to low stereoselectivity is low.

Wherein P and P ₁ are hydroxy protecting groups, Ac is an acetyl group and X is bromo or chloro.

U.S. Patent No. 5,453,499 discloses α-halo anomer 21 compared to β-halo anomer by reacting β-sulfonyloxy compound (20) with a halide source in an inert solvent as shown in Scheme 7 above. A method of producing at a high ratio of from 10 to 1 is described.

Wherein P and P ₁ are hydroxy protecting groups such as benzoyl and the like, P ₂ is sulfonyl and X is halide.

The starting material β-sulfonyloxy compound 20 is prepared from the corresponding 1-hydroxy compound as described, for example, in US Pat. No. 5,401,861, wherein α-sulfonyloxy anomer and β-sulfonyloxy Since the anomer is produced in a ratio of 1: 4, considering the process of purely separating the β-sulfonyloxy anomer from the α- and β-mixtures, the α-halo anomer is 9: 1 to 10: Even if obtained at a high ratio of 1 (α-anomer: β-anomer), the stereoselective ratio of obtaining the final α-halo anomer 21 from the 1-hydroxy compound is only about 3: 1. . In addition, the α-halo anomer 21 in which the benzoyl group and the like are introduced as a 3- and 5-hydroxy group protecting group is obtained in an oil phase, so that the separation efficiency is low and uneconomical to purify this column column, which is not suitable for mass production. There is a problem of using a photography method. In particular, the oil phase obtained has a problem in that it is difficult to handle or store unlike a solid.

Korean Patent Application No. 10-2005-0041278 discloses a compound obtained by reacting a lactol compound (13) with a phosphphenyl halide compound in the presence of a base to produce a 1-phosphphenyloxy furanose derivative (22), as shown in Scheme 8. The process for producing α-halo anomer 21 is described by reacting a with a halide source followed by recrystallization.

However, this reaction not only has a complicated disadvantage of the reaction step, but also it is difficult to obtain a high purity compound because it is not easy to remove phosphphenyl acid generated as a by-product.

In addition, looking at the conventional method of the glycosylation reaction using 1-halo ribofuranose, U.S. Patent Nos. 5,744,597 and EP 577,304 disclose a ribofuranose derivative rich in α-halo anomer as shown in Scheme 9 below. A stereoselective anion glycosylation method is known in which 15) is reacted with an anionic nucleobase to produce β-nucleoside 16 having a nucleobase introduced at the β-position.

Wherein P and P ₁ are hydroxy protecting groups, W is an amino protecting group, M + is a cation and L is an iodo or sulfonyloxy group.

According to this method, an anion nucleobase is prepared by reacting a nucleobase with a strong base such as potassium t-butoxide, sodium hydride, and the like, and the ribofuranose derivative rich in α-haloomer (15). Glycosylation with yields not only β-nucleosides (16) but also α-nucleosides (17), which requires a separate and cumbersome process for preparing anionic nucleobases, in particular the tactics described above. As described above, since the glycosylation reaction proceeds non-stereoselectively, the desired β-nucleoside is not only obtained at a comparable ratio with the α-nucleoside, but also has a disadvantage that the separation yield is very low and inefficient and inefficient.

Thus, when the leaving group is subjected to glycosylation reaction using 1-halo ribofuranose which is a halide, the reaction is different from the case of using the α-sulfonate leaving group even when using pure α-anomer oriented only in the α-position. Non-stereoselective progress shows inferior results in which the desired α-nucleosides are prepared in very low yields.

In addition, the hydroxy protecting groups P and P ₁ introduced at positions 3 and 5 shown in the above reaction schemes are very difficult to exist independently, and thus have the limitation of introducing the same protecting groups.

Accordingly, it is an object of the present invention to prepare an optically pure 3R-hydroxypropane amide compound of the formula [8] and from the compound of the formula [8] various 3- and 5-hydroxy group protecting group of Was introduced from the optically pure D-erythro-2,2-difluoro-2-deoxy-1-oxoribose compound of formula (2) -deoxy-2 ', 2'-difluorosa It relates to a process for preparing ittidine.

Another object of the present invention is to provide a method for preparing the compound in high purity and high yield.

[Formula 1]

[Chemical Formula 5]

[Formula 8]

Wherein R ₁ and R ₂ are each independently benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, 4 as a protecting group. -t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group, R ₃ and R ₄ are each independently C ₁ to C ₃ alkyl, R ₅ is methyl or ethyl group, R ₆ is hydrogen, methyl or me Oxy.

In the present invention to solve the above technical problem

(1) reacting the ethyl 3-hydroxy propanoic acid ester compound of Formula 9 with an optically pure amine compound to prepare an optically pure 3R-hydroxy propane amide compound of Formula 8;

(2) preparing a compound of [Formula 7] by protecting the hydroxy group of the compound of Formula 8;

(3) hydrolyzing the compound of [Formula 7] to prepare the D-erythro-1-oxolaibos compound of [Formula 6];

(4) preparing a D-erythro-1-oxo ribose compound of [Formula 5] by protecting the hydroxy group at position 5 of D-erythro-1-oxo ribose of [Formula 6];

(5) preparing a lactol compound of [Formula 4] by reducing the D-erythro-1-oxo ribose compound of Formula 5;

(6) The lactol compound of [Formula 4] is reacted with methane sulfonic acid chloride in the presence of a base such as triethylamine, pyridine and diisopropyl ethylamine to give D-erythro-1-methanesulfonyloxyribofu of [Formula 3] Preparing a lanose derivative;

(7) Glyco while mixing the D-erythro-1-methanesulfonyloxyribofuranose derivative and nucleobase of [Formula 3] in an organic solvent such as toluene, 1,2-dichloroethane, anisole and xylene A silylation reaction to obtain a nucleoside of [Formula 2]; And

(8) 2'-deoxy-2 ', 2'-difluorocytidine of the following [Formula 1] comprising the step of deprotecting the nucleoside of [Formula 2] obtained in step (7); Method for producing the salt.

Wherein R ₁ and R ₂ are each independently benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, 4 as a protecting group. -t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group, R ₃ , R ₄ and R ₇ are each independently C ₁ to C ₃ alkyl, R ₅ is methyl or ethyl group, R ₆ is hydrogen, methyl Or methoxy and P 'is acetyl or hydrogen.

The method for preparing oxo ribose of [Formula 5] used as a reaction intermediate in the method of the present invention is described in Korean Patent Application No. 10-2007-28526 filed by the present inventors (Invention: Optically pure oxo ribose derivative) Method of preparation) is described in detail.

In the present invention, the term 'anomer-rich' means that a certain anomer is present in excess of 1 times or more with respect to other anomers, and refers to an anomer mixture containing 98% or more of substantially pure anomers. In addition, 'anomerization' means that epimerization occurs at the C-1 position of ribofuranose in the state of pure anomer alone or in the mixture of α- and β-anomers.

If outlined the method of the present invention shown in Scheme 10,

(1) The optically pure D-erythro-2,2-difluoro-2-deoxy-1-oxoribose compound of [Formula 5] having various protecting groups introduced into 3- and 5-hydroxy groups is conventionally used. By reducing the phosphorus method to prepare a lactol compound of [Formula 4] in which the α-anomer and β-anomer mixed in the 1-position,

(2) preparing a 1-methanesulfonyl furanose derivative of [Chemical Formula 3] by reacting the obtained lactol compound of [Chemical Formula 4] with a methane sulfonic acid chloride in the presence of a base;

(3) glycosylation of the obtained 1-methanesulfonyl furanose derivative compound of [Formula 3] with acetylcytosine, a nucleobase, to prepare a nucleoside of [Formula 2],

(4) The protective group of the obtained nucleoside of [Formula 2] is deprotected to provide a method for producing 2'-deoxy-2 ', 2'-difluorocytidine of [Formula 1].

The reaction intermediate D-erythro-1-oxo ribose compound of [Formula 5] of [Formula 9] in which 3R-, 3S-hydroxy enantiomer is mixed at a constant ratio according to Korean Patent Application No. 10-2007-28526 The alkyl 3-hydroxy propanoic acid ester mixture was prepared using optically pure amine to prepare an optically pure 3R-hydroxy propane amide compound of Formula 8, and various protecting groups on the hydroxy group at position 3 of this compound. It introduces and manufactures [Formula 7]. Reaction with an acid to prepare a D-erythro-5-hydroxy-1-oxo ribose compound of [Chemical Formula 6] having a D-erythro structure and to protect the 5-hydroxy group by a conventional method 2 of [Formula 5] , 2-difluoro-2-deoxy-1-oxoribose compound can be prepared.

At this time, since the protecting groups for protecting the hydroxy group can be used independently of each other, it is possible to control the physical properties of the compound of [Formula 5] by the introduction of the selective protecting group. .

In more detail, the D-erythro-1-oxoribose compound of Formula 5 is reduced by a conventional method. Non-hydrogenated solvents such as tetrahydrofuran, diethyl ether and dioxane can be used as the solvent, and lithium aluminum hydride, hydrogenated diisobutyl aluminum, red al (hydrogen bis (2-methoxyethoxy) aluminum) as a reducing agent Sodium), lithium hydride tri-tert-butoxyaluminum, preferably red eggs. At this time, the reaction temperature is preferred because it is possible to react at room temperature for 1 to 2 hours after the addition of a reducing agent at -5 to 0 ° C mild temperature conditions.

The obtained lactol compound of [Formula 4] is reacted with a methane sulfonic acid chloride compound in the presence of a base such as triethylamine, pyridine, diisopropyl ethylamine, and 1-methanesulfonyloxylai of [Formula 3] rich in α-anomer. It was possible to obtain a bofuranose compound and glycosylated the 1-methanesulfonyloxyribofuranose compound of [Formula 3] and nucleobase acetylcytosine, which is rich in α-anomer, to form β- of [Formula 2]. The nucleoside in the anomer form was prepared, and finally, the protecting group of the nucleoside was deprotected by addition of ammonia / methanol solution to give 2'-deoxy-2 ', 2'-difluorocyti of [Formula 1]. Prepare a Dean.

The present invention utilizes optically pure D-erythro-2,2-di by the reaction with optically pure amine in the preparation of gemcitabine, an anticancer agent widely used to treat non-small cell lung cancer, pancreatic cancer, bladder cancer, breast cancer or ovarian cancer. It was possible to prepare a fluoro-2-deoxy-1-oxoribose compound, wherein the method of the present invention was developed through the development of an intermediate in which the hydroxy groups at positions 3 and 5 of the compound were independently introduced. Gemcitabine can be prepared in high purity and high yield.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are only intended to help understanding of the present invention, but the scope of the present invention is not limited thereto.

Example 1 Ethyl 2,2-Difluoro-3-hydroxy-3- (2,2-dimethyl- [1,3] dioxolan-4-yl) propionate

13 g (200 mmol) of zinc are added to 26 mL of tetrahydrofuran, 0.51 mL of 1,2-dibromoethane is added, followed by heating to 60 ° C. for 1 minute. 0.76 mL (6 mmol) of chlorotrimethylsilane are added at 40 ° C. After 10 minutes, the internal temperature was raised to 60 ° C., 25.5 mL (200 mmol) of ethyl bromodifluoroacetate, 30.8 g (237 mmol) of 2,2-dimethyl- [1,3] -dioxolane-4-carboaldehyde ) And 39 mL of tetrahydrofuran solution are added dropwise to react with heating under reflux. The reflux is further heated for 30 minutes after the drop is complete. 65 mL of diethyl ether was added to the reaction solution and poured into 260 g of ice. 260 mL of 1 N hydrochloric acid is added thereto and stirred until the ice is dissolved. The aqueous layer is extracted three more times with 90 mL of diethyl ether. The combined organic layers are washed with 65 mL of brine and 65 mL of saturated sodium bicarbonate. After drying over anhydrous magnesium sulfate and filtration, the residue was distilled under vacuum of 10 Torr to obtain an organic layer separated at a temperature of 130 to 134 ℃ to give a colorless liquid 28.9 g (yield: 57%) of the title compound (R: S = 3: 1).

¹ H NMR (CDCl ₃ , 300 MHz): 3.7-4.4 (m, 6H), 2.90 (d, 1H, (S) -OH), 2.67 (s, 1H, (R) -OH), 1.31-1.52 ( m, 9H)

Example 2. 3R- (2,2-dimethyl-1,3-dioxolan-4-yl) -2,2-difluoro-3-hydroxy-N-[(S) -1-phenylethyl ] Synthesis of Propaneamide

150 g of ethyl 2,2-difluoro-3-hydroxy-3- (2,2-dimethyl- [1,3] dioxolan-4-yl) propionate (R: S = 3: 1) Dissolve (590 mmol) in 750 mL of toluene, add a catalytic amount of sodium cyanide, and slowly add dropwise 75 mL (590 mmol) of (S)-(-)-α-methylbenzylamine. The reaction solution is heated to reflux for one day. Ethyl acetate was added to the reaction solution, and the mixture was washed three times with 2,000 mL of water. Dry over anhydrous magnesium sulfate, filter and distillation under reduced pressure to obtain a brown solid compound. Recrystallization using hexane or a mixture of hexane and ethyl acetate gives 105 g (54% yield) of a pale off-white solid.

¹ H NMR (CDCl ₃ , 400 MHz): 7.39-7.28 (m, 5H), 6.66 (m, NH), 5.13 (m, 1H), 4.33-4.24 (m, 2H), 4.05-4.03 (m, 2H) , 1.56 (d, 3H, J = 6.9), 1.31 (s, 3H), 1.29 (s, 3H)

Example 3. (R) -1-((R) -2,2-dimethyl-1,3-dioxolan-4-yl) -2,2-difluoro-3-oxo-3-(( Synthesis of S) -1-phenylethylamine) propyl benzoate

3R- (2,2-dimethyl-1,3-dioxolan-4-yl) -2,2-difluoro-3-hydroxy-N-[(S) -1- obtained in Example 2 50 g (152 mmol) of phenylethyl] propaneamide are dissolved in 200 mL of methylene chloride, and then 32 mL (228 mmol) of triethylamine are added, and 19 mL (167 mmol) of benzoyl chloride are added to the reaction solution. After stirring for 2 hours at room temperature, the mixture was washed with 600 mL of 1N hydrochloric acid, 600 mL of 5% sodium bicarbonate solution and 600 mL of water. Anhydrous magnesium sulfate was added, dried, filtered and distilled under reduced pressure to obtain a white solid compound. The obtained solid was recrystallized with a hexane-ethyl acetate mixed solution to give 58.0 g (yield: 88%) of a white solid compound.

¹ H NMR (CDCl ₃ , 400 MHz): 8.02 (d, 2H, J = 7.2), 7.62-7.59 (m, 1H), 7.47-7.43 (m, 2H), 7.37-7.29 (m, 5H), 6.54 ( m, NH), 5.95 (m, 1H), 5.12 (m, 1H), 4.54 (m, 1H), 4.12-4.00 (m, 2H), 1.47 (d, 3H, J = 6.9), 1.28 (s, 3H), 1.19 (s, 3H)

Example 4. (R) -1-((R) -2,2-Dimethyl-1,3-dioxolan-4-yl) -2,2-difluoro-3-oxo-3-(( S) -1-phenylethylamine) propyl 2-naphthoate

63.9 g (yield: 87%) of a white solid compound were obtained by using 2-naphthoyl chloride instead of benzoyl chloride by the same procedure as in Example 3.

¹ H NMR (CDCl ₃ , 400 MHz): 8.62 (s, 1H), 8.03 (dd, 1H, J = 1.6, 8.6), 7.95 (d, 1H, J = 8.0), 7.91-7.88 (m, 2H), 7.65-7.55 (m, 2H), 7.34-7.26 (m, 5H), 6.58 (m, NH), 6.06-5.98 (m, 1H), 5.15-5.08 (m, 1H), 4.62-4.57 (m, 1H ), 4.16-4.08 (m, 2H), 1.46 (d, 3H, J = 6.9), 1.29 (s, 3H), 1.19 (s, 3H)

Example 5: Synthesis of 2-deoxy-2,2-difluoro-3-benzoyl-5- (2-naphthoyl) -D-erythropentopuranose-1-ulose

(R) -1-((R) -2,2-dimethyl-1,3-dioxolan-4-yl) -2,2-difluoro-3-oxo-3- obtained in Example 3 30 g (68 mmol) of ((S) -1-phenylethylamine) propyl benzoate was dissolved in 150 mL of acetonitrile, and 14 mL (170 mmol) of concentrated hydrochloric acid was added thereto, followed by heating to reflux for 4 hours. After the reaction is completed, toluene is added to the reaction mixture to remove the solvent and water by distillation. Toluene was added to the reaction mixture again, distillation was carried out, and the mixture was concentrated completely to obtain 2-deoxy-2,2-difluoro-D-erythropentopuranos-1-ulose-3-benzoate. The reaction mixture is dissolved in 100 mL of methylene chloride and then 8.2 mL (102 mmol) of pyridine is added. 13 g (68 mmol) of 2-naphthoyl chloride dissolved in 40 mL of methylene chloride are added to the reaction solution. After stirring for 12 hours at room temperature, 200 mL of 1N hydrochloric acid, 200 mL of 5% sodium bicarbonate solution and 200 mL of water are washed. Dry over anhydrous magnesium sulfate, filter and distillation under reduced pressure. The obtained solid was recrystallized with a hexane-ethyl acetate mixed solution to obtain 20 g of a white solid compound (yield: 70%).

¹ H NMR (DMSO-d ₆ , 400 MHz): 8.64 (s, 1H), 8.07 (d, 2H, J = 7.2), 8.05 (dd, 1H, J = 1.6, 8.6), 7.97 (d, 1H, J = 8.0), 7.91-7.89 (m, 2H), 7.66-7.56 (m, 3H), 7.50-7.47 (m, 2H), 5.89-5.78 (m, 1H), 4.60-4.57 (m, 1H), 4.50 -4.43 (m, 2H)

Example 6: Synthesis of 2-deoxy-2,2-difluoro-5-benzoyl-3- (2-naphthoyl) -D-erythropentopuranose-1-ulose

20.6 g (yield: 67%) of a white solid compound were obtained by using 2-naphthoyl chloride instead of benzoyl chloride by the same procedure as in Example 5.

¹ H NMR (DMSO-d ₆ , 400 MHz): 8.62 (s, 1H), 8.05 (d, 2H, J = 7.2), 8.03 (dd, 1H, J = 1.6, 8.6), 7.95 (d, 1H, J = 8.0), 7.89-7.87 (m, 2H), 7.65-7.53 (m, 3H), 7.48-7.45 (m, 2H), 6.05-5.95 (m, 1H), 4.62-4.58 (m, 1H), 4.51 -4.43 (m, 2H)

Example 7.Synthesis of 2-deoxy-2,2-difluoro-3-benzoyl-5- (2-naphthoyl) -1-methanesulfonyloxy-D-ribofuranose

17.9 g (42 mmol) of 2-deoxy-2,2-difluoro-3-benzoyl-5- (2-naphthoyl) -D-erythropentopuranos-1-ulose obtained in Example 5 After dissolving in 400 mL of tetrahydrofuran, it is cooled to -5 ~ 0 ℃. 15.1 mL (50 mmol) of red-al (65 wt% in toluene) is slowly added dropwise, and the mixture is stirred for 5 hours while maintaining at −5˜0 ° C. 100 mL of 1N hydrochloric acid solution was slowly added dropwise to the reaction solution to terminate the reaction, and 400 mL of ethyl acetate was added. The organic layer was washed with 1,000 mL of 5% sodium bicarbonate solution and 1000 mL of brine, dried over anhydrous magnesium sulfate, filtered and distilled under reduced pressure to obtain crude 2-deoxy-2,2-difluoro-3-benzoyl-5- Obtain (2-naphthoyl) -D-ribofuranose and dissolve in 100 mL of methylene chloride and add 11.97 mL (88 mmol) of triethylamine. 3.99 mL (51 mmol) of methane chloride sulfonic acid was added to the reaction solution, the mixture was stirred at room temperature for 4 hours, the solvent was distilled off under reduced pressure, and 150 mL of ethyl acetate was added thereto. The organic layer is washed with 400 mL of 1N hydrochloric acid, 400 mL of 5% sodium bicarbonate and 400 mL of brine. Anhydrous magnesium sulfate was added, dried, filtered and concentrated under reduced pressure to give 13.6 g of a white solid compound (yield: 66%).

¹ H NMR (CDCl ₃ , 400 MHz): 8.63 (s, 1H), 8.07-8.05 (m, 2H), 7.97-7.89 (m, 3H), 7.66-7.55 (m, 3H), 7.49-7.47 (m, 2H), 5.89-5.76 (m, 1H), 4.60-4.57 (m, 1H), 4.50-4.43 (m, 2H), 4.00 (s, 1H), 3.39 (s, 3H)

Example 8. Synthesis of 2-deoxy-2,2-difluoro-5-benzoyl--3- (2-naphthoyl) -1-methanesulfonyloxy-D-ribofuranose

Example 6 instead of 2-deoxy-2,2-difluoro-3-benzoyl-5- (2-naphthoyl) -D-erythropentopuranos-1-ulose by the same procedure as in Example 7. 13.2 g of a white solid compound using 2-deoxy-2,2-difluoro-5-benzoyl-3- (2-naphthoyl) -D-erythropentopuranos-1-ulose obtained in Yield: 64%) was obtained.

¹ H NMR (CDCl ₃ , 400 MHz): 8.64 (s, 1H), 8.07-8.05 (m, 2H), 7.97 (m, 1H), 7.91-7.89 (m, 2H), 7.67-7.49 (m, 5H) , 6.06-5.97 (m, 1H), 4.64-4.59 (m, 1H), 4.54-4.43 (m, 2H), 3.99 (s, 1H), 3.38 (s, 3H)

Example 9. 1-2'-deoxy-2 ', 2'-difluoro-3-benzoyl-5- (2-naphthoyl) -D-ribofuranosyl-4- (1-acetyl) amino Synthesis of pyrimidin-2-ones

8.3 g (54 mmol) of acetyl cytosine, 26 mL (126 mmol) of hexamethyldisilazane, 1.1 mL (9 mmol) of trimethylsilyl chloride, and 20 mL of toluene are mixed and heated to reflux. After complete dissolution, the mixture is heated to reflux for 3 hours. The reaction solution is cooled to room temperature and then distilled to remove excess hexamethyldisilazine and trimethylsilyl chloride. Toluene was added to the reaction solution again and distilled again. Under nitrogen atmosphere, 20 mL (108 mmol) of trimethylsilyl trifluoromethane sulfonate was added dropwise and 2-deoxy-2,2-difluoro-3-benzoyl-5- (2- obtained in Example 7 was obtained. 9 g (18 mmol) of naphthoyl) -1-methanesulfonyloxy-D-ribofuranose are dissolved in 50 mL of toluene, added dropwise to the reaction solution and heated to reflux for 15 hours. After cooling to room temperature, 100 mL of ethyl acetate is added. The organic layer was washed with 300 mL of 1N hydrochloric acid, 300 mL of 5% sodium bicarbonate and 300 mL of brine. Anhydrous magnesium sulfate was added, dried, filtered and concentrated under reduced pressure to yield 8.9 g (yield: 88%) of a white solid compound.

¹ H NMR (DMSO-d ₆ , 400 MHz): 8.63 (s, 1H), 8.19-8.15 (m, 1H), 8.07-8.05 (m, 2H), 7.97-7.89 (m, 3H), 7.66-7.55 ( m, 3H), 7.49-7.47 (m, 2H), 6.29-6.26 (m, 1H), 5.89-5.76 (m, 1H), 4.60-4.57 (m, 1H), 4.50-4.43 (m, 2H), 4.00 (s, 1 H), 2.14 (s, 3 H)

Example 10. 1-2'-deoxy-2 ', 2'-difluoro-3- (2-naphthoyl) -5-benzoyl-D-ribofuranosyl-4- (1-acetyl) amino Synthesis of pyrimidin-2-ones

Instead of 2-deoxy-2,2-difluoro-3-benzoyl-5- (2-naphthoyl) -1-methanesulfonyloxy-D-ribofuranose by the same procedure as in Example 9 White using 2-deoxy-2,2-difluoro-5-benzoyl--3- (2-naphthoyl) -1-methanesulfonyloxy-D-ribofuranose obtained in Example 8 8.5 g (yield 84%) of solid compound were obtained.

¹ H NMR ((DMSO-d ₆ , 400 MHz): 8.64 (s, 1H), 8.20-8.16 (m, 1H), 8.07-8.05 (m, 2H), 7.97 (m, 1H), 7.91-7.89 (m , 2H), 7.67-7.49 (m, 5H), 6.30-6.26 (m, 1H), 6.06-5.97 (m, 1H), 4.64-4.59 (m, 1H), 4.54-4.43 (m, 2H), 3.99 (s, 1H), 2.12 (s, 3H)

Example 11.Synthesis of 2'-deoxy-2 ', 2'-difluorocytidine hydrochloride

1-2'-deoxy-2 ', 2'-difluoro-3-benzoyl-5- (2-naphthoyl) -D-ribofuranosyl-4- (1-acetyl obtained from Example 9 8.5 g (15 mmol) of aminopyrimidin-2-one are added to 85 mL of 7N-ammonia / methanol solution (Aldrich), and 170 mL of methanol is further added thereto. The mixture was stirred overnight at room temperature, distilled under reduced pressure to remove the solvent, and stirred with 100 mL of water and 70 mL of ethyl acetate. The aqueous layer was separated, and the ethyl acetate layer was extracted once more with 30 mL of water. The aqueous layers were combined, the aqueous layer washed with 40 mL of petroleum ether, and 130 mL of IPA was added to the aqueous layer and concentrated under reduced pressure. 30 mL of IPA was added to the residue, dissolved by heating, and then 0.92 mL of concentrated hydrochloric acid was added and cooled to room temperature. The mixture was stirred at room temperature for 2 hours to ripen the crystals, and the precipitated crystals were filtered, washed with acetone mixed solution and dried to give 2.9 g (64%) of a white solid compound.

¹ H NMR (DMSO-d ₆ , 400 MHz): 10.21 (s, 1H), 9.00 (s, 1H), 8.22 (d, 1H), 6.31 (d, 1H), 6.08 (t, 1H), 4.26-4.17 (m, 1H), 3.95-3.91 (m, 1H), 3.81 (d, 1H), 3.66 (dd, 1H)

Example 12.Synthesis of 2'-deoxy-2 ', 2'-difluorocytidine hydrochloride

1-2'-deoxy-2 ', 2'-difluoro-3-benzoyl-5- (2-naphthoyl) -D-ribofuranosyl-4- (1) by the same procedure as in Example 11 1- 2'-deoxy-2 ', 2'-difluoro-3- (2-naphthoyl) -5-benzoyl-D-ribofuranosyl- instead of -acetyl) aminopyrimidin-2-one 4- (1-acetyl) aminopyrimidin-2-one was used to yield 3.0 g (66%) of a white solid compound.

¹ H NMR (DMSO-d ₆ , 400 MHz): 10.08 (s, 1H), 8.93 (s, 1H), 8.17 (d, 1H), 6.39 (d, 1H), 6.08 (t, 1H), 4.24-4.18 (m, 1H), 3.93-3.90 (m, 1H), 3.81 (d, 1H), 3.65 (dd, 1H)

Claims (7)

The ethyl 3-hydroxy propanoic acid ester compound in which the (R) -form and the (S) -form optical isomer were mixed with (S) -phenylethanamine, (S) -1- (4-methylphenyl) ethanamine, ( Amine with optical activity selected from S) -1-phenyl-1-propanamine, (S) -1- (4-methoxyphenyl) ethanamine, and (S) -1- (4-chlorophenyl) ethanamine Method for preparing 2'-deoxy-2 ', 2'-difluorocytidine and its salts by the following preparation step using an optically pure reaction intermediate compound prepared by optical division. (1) reacting the ethyl 3-hydroxy propanoic acid ester compound of Formula 9 with an optically pure amine compound to prepare an optically pure 3R-hydroxy propane amide compound of Formula 8; (2) preparing a compound of [Formula 7] by protecting the hydroxy group of the compound of Formula 8; (3) hydrolyzing the compound of [Formula 7] to prepare the D-erythro-1-oxoribose compound of [Formula 6]; (4) preparing a D-erythro-1-oxo ribose compound of [Formula 5] by protecting the hydroxy group at position 5 of D-erythro-1-oxo ribose of [Formula 6]; (5) preparing a lactol compound of [Formula 4] by reducing the D-erythro-1-oxo ribose compound of Formula 5; (6) The lactol compound of [Formula 4] is reacted with methane sulfonic acid chloride in the presence of a base selected from triethylamine, pyridine and diisopropyl ethylamine to give D-erythro-1-methanesulfonyloxylai of [Formula 3] Preparing a bofuranose derivative; (7) While mixing the D-erythro-1-methanesulfonyloxyribofuranose derivative and nucleobase of [Formula 3] with an organic solvent selected from toluene, 1,2-dichloroethane, anisole and xylene Lycosylation reaction to obtain the nucleoside of [Formula 2]; And (8) 2'-deoxy-2 ', 2'- of [Formula 1] comprising the step of deprotecting the nucleoside of [Formula 2] obtained in step (7) by adding ammonia / methanol solution Method for producing difluorocytidine and salts thereof. [Formula 1]

[Formula 2]

(3)

[Formula 4]

[Chemical Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

Wherein R ₁ and R ₂ are each independently a protecting group as benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, 4 -t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group, R ₃ and R ₄ are each independently C ₁ to C ₃ alkyl, R ₅ is a methyl or ethyl group, R ₆ is hydrogen, methyl or methoxy R ₇ is ethyl and P 'is an acetyl group or hydrogen. delete The method of claim 1, In step (2) and step (4), the protecting groups are each independently benzoyl, 4-methylbenzoyl, 3-methylbenzoyl, 4-cyanobenzoyl, 3-cyanobenzoyl, 4-propylbenzoyl, 2-ethoxybenzoyl, A 4-t-butylbenzoyl, 1-naphthoyl or 2-naphthoyl group. delete delete delete delete