KR20060102602A - Novel Method of Making Critosine - Google Patents

Abstract

The present invention relates to a novel process for the preparation of the clitocine of the formula with excellent anticancer and antiviral effects. The present invention also provides novel compounds that can be used in such preparation methods. According to the present invention, a column purification process is not necessary and the production of α-anomer can be suppressed as much as possible, thereby making it possible to produce the desired cletosine with high purity.

Description

Novel Process for Preparation of Clitocine

1 is an X-ray crystal structure of the novel compound of Formula 3 used as a reactant in the preparation method of the present invention.

The present invention relates to a novel method for producing clintoxin (Clitocine), and more particularly, provides a method for producing clintoxin with high purity by eliminating the need for column purification and maximally inhibiting the production of α-anomer. The present invention also provides novel compounds that can be used in such preparation methods.

The nucleoside clittocin [6-amino-5-nitro-4- (β-D-ribofuranosylamino) pyrimidine] was obtained from a mushroom named Clitocybe inversa by Kubo Group in 1986 and its structure is elucidated. It has been shown to have anti-cancer and antiviral effects with excellent insecticidal effects (Kubo, I .; Kim, M .; Wood, WF; Naoki, H. Tetrahedron Lett. 1986 , 27 , 4277).

To date, two groups have reported the synthesis of cittocin. The Kamikawa group synthesized cittocin by the polymerization of ribofuranosylamine derivatives and 4-chloro-5-nitropyrimidine derivatives. However, there is a problem in that the overall yield and selectivity of the desired β-anomer are low (Kamikawa, T .; Fujie, S .; Yamagiwa, Y .; Kim, M .; Kawaguchi, H.). J. Chem. Chem., Chem. Commun. 1988 , 195).

Meanwhile, the Kini group is glycosylation of 1- O -acetyl-2,3,5-tri- O -benzoyl-D-ribofuranose of 4,6-diamino-5-nitropyrimidine protected with a silyl group. Clittocin was synthesized using (Moss, RJ; Patrie, CR; Meyer, Jr., RB; Nord, D .; Willis, RC; Smith, RA; Larson, SB; Kini, GD; Robins, RK J. Med. Chem. 1988 , 31 , 786). Also in this case, the glycosylation result has to be purified by a column, and in addition, the aomeromer isomerized in the deprotection step of the benzoyl group to generate an undesired α-anomer.

Therefore, there is a high demand for a new manufacturing method that can solve the problems of the prior art and the technical problem that has been requested from the past.

After numerous studies and in-depth studies, the present inventors can obtain the result in high purity without undergoing a column separation process that is difficult to apply industrially as described in detail below. By maximally suppressing, it was possible to develop a novel manufacturing method of clintocin that can obtain the desired result in high yield.

In addition, in the course of these studies, new compounds that have not been known so far could be synthesized.

Therefore, the method for preparing the clintocin of formula 1 according to the present invention,

(a) isomerizing a compound of Formula 3 to produce a compound of Formula 4; And

(b) deprotecting the hydroxy protecting group in the compound of Formula 4 to prepare a compound of Formula 1;

It is configured to include.

(1)

(One)

(3)

(3)

(4)

(4)

In the above formulas,

R is an acyl group of the formula R ¹ CO, where R ¹ is hydrogen, a C ₁ -C ₇ saturated alkyl, C ₂ -C ₇ unsaturated alkyl or aryl group having 0 to 3 substituents. The aryl group specifically includes both monocyclic or bicyclic compounds having 0 to 3 substituents, 5 to 10 hexagonal carbon or heterocyclic compounds and their analogs partially reduced.

The isomerization reaction in step (a) may preferably be carried out at a temperature of 0 to 50 ° C., more preferably at room temperature, in the presence of a catalyst. The isomerization catalyst may include 10 to 1000 wt% of silica gel or 0.05 to 3.0 molar equivalents of inorganic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, or a formula RCOOH, wherein R is 0 to 3 Organic acids of C ₁ -C ₁₀ saturated or unsaturated alkyl or aryl groups with substituents can be preferably used. It is more preferable to use silica gel or a volatile organic acid in view of easy reaction finishing.

Isomerization can be carried out in an organic solvent such as acetonitrile, methylene chloride, tetrahydrofuran, ethyl acetate, diethyl ether, toluene or t- butyl methyl ether.

The hydroxyl group-deprotection reaction in step (b) may be carried out at a temperature of −10 to 10 ° C. in the presence of a catalyst, with a more preferred reaction temperature of 0 ° C. to prevent the production of α-anomers.

Potassium ethoxide, sodium methoxide, sodium ethoxide and the like may be used as the catalyst for the deprotection reaction.

More preferred protecting groups (R ¹ CO) to prevent the formation of α-anomers during the hydroxy group-deprotection reaction of compounds of formula 4 are α-methoxyacetyl, α-chloroacetyl, α, α′-dichloro acetyl , p -chlorobenzoyl, dichlorobenzoyl, p -bromobenzoyl or p -nitrobenzoyl. In this case, sodium methoxide is particularly preferred as a hydroxy deprotection catalyst.

The production method according to the present invention does not require a column purification process that is difficult to apply industrially, and isomerized to α-anomer in the deprotection process, or at least greatly suppressed, so that it is possible to produce clintocin with high purity. There is this.

The present invention also provides a compound of formula 3, which is a novel compound per se.

The compound of formula (3) can be prepared, for example, by condensation reaction of a compound of formula (6) with a compound of formula (2) after protecting its primary amine groups.

(2)

(2)

(6)

(6)

Wherein R is an acyl group of the formula R ¹ CO, wherein R ¹ is as defined above.

The compound of the formula (3) may have not only a use as a reactant of the method for producing clittocin, but also a use as it is, and also as a raw material for the synthesis of other substances, intermediates and the like.

The two primary amine groups in formula (6) may preferably be protected with a silyl group, for example trimethylsilyl by reflux stirring in hexamethyldisilazane (HMDS) and pyridine in the presence of catalytic amounts of sulfuric acid and ammonium sulfate Can be protected by The compound in which the amine group is protected by the silyl group is represented by the following formula (6a).

(6a)

(6a)

Wherein R is the same as defined above.

The condensation reaction may preferably be carried out at a temperature of 0 to 50 ° C., preferably at room temperature, in the presence of Lewis acid as a catalyst. Preferred examples of the Lewis acid include trimethylsilyl trifluoromethanesulfonate (TMSOTf), boron trifluoride ethyl ether complex (BF ₃ -OEt ₂ ), aluminum chloride having 0 to 3 alkyl groups (R _n AlCl). _(3-n) ), titanium chloride having 0-4 alkoxy groups ((RO) _n TiCl _(4-n) ), and the like, preferably trimethylsilyl trifluoromethanesulfonate (TMSOTf) may be used. . Lewis acids are used in 0.5 to 3.0 molar equivalents, more preferably 1.7 molar equivalents.

As a solvent for the condensation reaction, for example, acetonitrile, methylene chloride, tetrahydrofuran, ethyl acetate and the like are used, and acetonitrile is preferably used.

When p -chlorobenzoyl is used as the hydroxy protecting group of the compound of the formula (2), it is possible to obtain the compound of the formula (3) as a solid. In this case, the crude product obtained after the completion of the reaction is precipitated with ethyl acetate, diethyl ether, toluene, t - butyl methyl ether, etc. Given the high purity, the compound of formula 3 can be obtained.

The compound of Formula 2 may be prepared by, for example, a known method from 1- O -methyl-D-ribofuranose of Formula 5 below (Shi, Z.-D .; Yang, B.-H Wu, Y.-L. Tetrahedron 2002 , 58 , 3287.), where detailed description thereof is omitted.

(5)

(5)

A series of processes for preparing the clintocin of formula 1 from the compound of formula 5 can be represented, for example, by the following scheme.

In some cases, other processes may be added to the production method of the present invention without departing from the effect of the invention.

The present invention is explained in more detail in the following examples, but the scope of the present invention is not limited thereto.

Preparation Example 1 1- O Preparation of -methyl-D-ribofuranose

A mixture of methanol (160 mL) and acetyl chloride (0.91 mL, 0.01 mol) was stirred for 30 minutes and then D-ribose (30 g, 0.2 mol) was added. After stirring the reaction solution for 18 hours at room temperature, triethylamine (4 mL) was added dropwise and distilled under reduced pressure to remove the solvent to give the title compound in 116% (38.1 g) yield.

Preparation Example 2 1- O -Methyl-2, 3, 5-tri- O - p Preparation of -chlorobenzoyl-D-ribofuranose

1- O -Methyl-D-ribofuranose (38.1 g) was placed in a 2 L flask equipped with a mechanical stirrer and methylene chloride (250 mL) and triethylamine (190 mL, 1.0 mol) were added. p -chlorobenzoyl chloride (90 mL, 0.70 mol) and dimethylaminopyridine (DMAP, 720 mg, 6.0 mmol) were added dropwise, and the reaction solution was stirred at room temperature for 5 hours. Water (200 mL) was added to terminate the reaction, and the organic layer was separated. The water layer was extracted with methylene chloride (200 mL, and 100 mL × 2), and the organic layers were collected and washed with a mixed solution of saturated sodium bicarbonate solution and saturated brine 1: 1 (200 mL). After distillation under reduced pressure to remove the solvent, it was dissolved in methylene chloride (250 mL) and washed with 1N HCl (80 mL), water (100 mL) and saturated sodium bicarbonate solution (100 mL). Water in the organic layer was removed with anhydrous magnesium sulfate and distilled under reduced pressure to obtain 128 g of the title compound.

Preparation Example 3 1- O -Acetyl-2,3,5-tri- O - p Preparation of -chlorobenzoyl-D-ribofuranose

Acetic anhydride (19.3 mL, 0.204 mol) in methylene chloride (200 mL) solution of 1- O -methyl-2,3,5-tri- O - p -chlorobenzoyl-D-ribofuranose (128 g) ), Acetic acid (24.3 mL, 0.426 mol) and sulfuric acid (2.7 mL, 0.05 mol) were added and stirred at room temperature for 19 hours. 10 mL (0.106 mol) of acetic acid was further added and stirred for 3 hours. The reaction was terminated with sodium acetate (5 g) and water (200 mL), the organic layer was separated and the water layer was extracted with methylene (100 mL x 2). The combined organic layers were diluted with methylene chloride (300 mL), washed with saturated aqueous sodium bicarbonate solution (600 mL total), and water was removed with anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure, ethyl acetate (150 mL) was added to the resulting foam, and the resulting precipitate was filtered and washed with ethyl acetate (20 mL x 3) and hexane (30 mL x 2). A mixture of the title compound (54.15 g, 44.5% for three steps) and 76.8 g (63% for three steps) of α- and β-anomers (1: 0.6) was obtained in powder form.

α-anomer: ¹ H NMR (DMSO- d ₆ , 400 MHz): δ 8.01 (2H, dd, J = 7.2 Hz and 2.0 Hz), 7.96 (2H, dd, J = 7.2 Hz and 2.0 Hz) , 7.83 (2H, dd, J = 7.2 Hz and 2.0 Hz), 7.62 (2H, dd, J = 7.2 Hz and 2.0 Hz), 7.60 (2H, dd, J = 7.2 Hz and 2.0 Hz), 7.53 (2 H, dd, J = 7.2 Hz and 2.0 Hz), 6.32 (1 H, s), 5.82 (1 H, dd, J = 4.8 Hz and 7.2 Hz), 5.70 (1 H, d, J = 5.2 Hz ), 4.83 (1 H, m), 4.71 (1 H, dd, J = 3.6 Hz and 12.4 Hz), 4.50 (1 H, dd, J = 3.6 Hz and 12.4 Hz).

¹³ C NMR (DMSO- d ₆ , 100 MHz): δ 169.7, 165.3, 164.8, 164.6, 139.9, 139.7, 139.5, 132.1, 131.9, 130.0, 129.9, 129.8, 129.0, 128.2, 98.7, 80.1, 75.8, 71.9, 64.4, 21.5.

Mass (APCI, M + H): 702.

Example 1: 4-amino-6-imino-5-nitro-1- N -(2,3,5-tree- O - p Preparation of -chlorobenzoyl-β-D-ribofuranosyl) pyrimidine

In a solution of 4,6-diamino-5-nitropyrimidine (1.0 g, 6.45 mmol) in hexamethyldisilazane (HMDS, 30 mL), pyridine (4.8 mL) and sulfuric acid (0.2 mL) ammonium sulfate (60 mg) ) Was added. The reaction solution was stirred under reflux at 130 ° C. for 18 hours, and concentrated by distillation under reduced pressure.

The remaining solid was dissolved in acetonitrile (50 mL) and cooled to 0 ° C., then 1- O -acetyl-2,3,5-tri- O - p -chlorobenzyl-D-ribofuranose (4.5 g, 7.42 mmol) and trimethylsilyl trifluoromethanesulfonate (TMSOTf, 2.0 mL, 11.0 mmol) were added. The dark and clear solution obtained by stirring the reaction solution at 0 ° C. for 23 hours was distilled under reduced pressure to remove acetonitrile. To the residue was added aqueous saturated sodium bicarbonate solution (100 mL) and extracted with methylene chloride (100 mL x 2). After collecting the organic layer, water was removed using anhydrous magnesium sulfate and distilled under reduced pressure. The precipitate obtained by adding ethyl acetate (4 mL) and a sufficient amount of diethyl ether to the foamed residue was collected and washed with ether to give 2.0 g (44%) of the title compound as a yellow powder.

¹ H NMR (DMSO- d ₆ , 400 MHz): δ 9.61 (1 H, s), 9.44 (1 H, s), 9.36 (1 H, s), 8.33 (1 H, s), 7.98 (2 H , dd), 7.94 (2H, dd), 7.57 (4H, 2 dd), 7.50 (2H, dd), 6.33 (1H, d, J = 2.4 Hz), 6.12 (1H, dd, J = 6.4 Hz and 2.4 Hz), 6.06 (1 H, dd, J = 7.2 Hz and 6.4 Hz), 4.6-4.8 (3 H, m).

¹³ C NMR (DMSO- d ₆ , 100 MHz): δ 164.8, 164.0, 163.9, 158.5, 152.3, 148.5, 139.0, 138.9, 138.7, 131.4, 131.3, 131.2, 129.2, 129.1, 128.2, 127.7, 127.5, 111.3, 91.2, 78.7, 74.1, 70.4, 63.7.

IR (cm ⁻¹ ): 3424, 3300, 1713, 1632, 1589, 1478, 1396, 1252, 1087, 1009, 752.

Example 2: 6-amino-5-nitro-4-[(2,3,5-tri- O - p -Chlorobenzoyl-β-D-ribofuranosyl) amino] pyrimidine

4-amino-6-imino-5-nitro-1- N- (2,3,5-tri- O - p -chlorobenzoyl-β-D-ribofuranosyl) pyrimidine (2.166 g, 3.08 mmol ) Was dissolved in methylene chloride (60 mL) and silica gel (2.2 g) was added. After stirring for 20 hours, the silica gel was removed by filtration, and the filtered solution was distilled under reduced pressure to obtain the title compound (1.93 g, 89%) in the form of a yellow foam.

_{^{1 H NMR (DMSO- d 6,}} 400 MHz): δ 9.60 (1 H, d, J = 8.0 Hz), 5.58 (2 H, bs), 8.05 (1 H, s), 8.00 (2 H, dd) , 7.90 (2H, dd), 7.84 (2H, dd), 7.55 (6H, 3 dd), 6.35 (1H, dd, J = 8.4 Hz, 4.8 Hz), 5.97 (1H, dd, J = 5.6 Hz and 4.8 Hz), 5.89 (1 H, dd, J = 6.0 Hz and 5.2 Hz), 5.76 (1 H, s), 4.65 (2 H, m), 4.55 (1 H, m).

¹³ C NMR (DMSO- d ₆ , 100 MHz): δ 165.5, 164.8, 164.7, 160.0, 159.4, 157.4, 139.8, 139.7, 139.4, 132.0, 131.9, 129.9, 129.8, 129.7, 128.9, 128.3, 128.2, 113.4, 84.8, 78.7, 75.1, 72.1, 64.8.

Example 3: Preparation of Clittocin

6-amino-5-nitro-4-[(2,3,5-tri- O - p -chlorobenzoyl-β-D-ribofuranosyl) amino] pyrimidine (1.93 g, 2.75 mmol) It was dissolved in 4-dioxin (26 mL) and diluted with methanol (65 mL). After the reaction was cooled to 0 ° C., sodium methoxide (0.55 mmol, 0.1 mL of 28% methanol solution + 0.4 mL of methanol) was added, and stirred at 0 ° C. for 6 hours. Amberlite IR-120 (plus) (900 mg, 3.96 mol equiv, used after washing with distilled water and methanol) was added to the reaction solution, followed by stirring and filtering for 30 minutes to remove the resin. The solvent was removed by distillation under reduced pressure, and the precipitate obtained by adding ether was filtered and washed with ether (10 mL × 3). The obtained solid was recrystallized from 135 mL of hot methanol to give the title compound (400 mg, 51%, β: α = 98.3: 1.7) as yellow crystals. The mother liquor was distilled under reduced pressure to obtain more 255 mg (32%) of clitosine.

_{^{1 H NMR (DMSO- d 6,}} 400 MHz): δ 9.28 (1 H, d, J = 7.6 Hz), 8.56 (2 H, s), 8.00 (1 H, s), 5.79 (1 H, dd, J = 7.6 Hz and 3.6 Hz), 5.20 (1 H, d, J = 5.2 Hz), 5.06 (1 H, t, J = 4.8 Hz), 4.92 (1 H, d, J = 6.0 Hz), 4.05 ( 1 H, m), 3.93 (1 H, m), 3.79 (1 H, m), 3.53 (1 H, m), 3.47 (1 H, m)

¹³ C NMR (DMSO- d ₆ , 100 MHz): δ 160.2, 159.5, 156.8, 112.8, 87.0, 84.8, 75.9, 70.8, 61.3

According to the present invention, it is possible to produce clitosine with high purity without the need for column purification, and to suppress the production of α-anomer as much as possible.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (16)

(a) isomerizing a compound of Formula 3 to produce a compound of Formula 4; And (b) deprotecting the hydroxy protecting group in the compound of Formula 4 to prepare a compound of Formula 1; Method for producing a clintocin of formula 1 consisting of:

(One)

(3)

(4) In the above formulas, R is an acyl group of the formula R ¹ CO, where R ¹ is hydrogen, a C ₁ -C ₇ saturated alkyl, C ₂ -C ₇ unsaturated alkyl or aryl group having 0 to 3 substituents. The process according to claim 1, wherein the isomerization reaction of step (a) is carried out at a temperature of 0 to 50 ° C in the presence of a catalyst. The method of claim 1, wherein the isomerization catalyst is based on the compound of formula 3, which is a reactant, 10 to 1000 wt% of silica gel, or 0.05 to 3.0 molar equivalents of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, or formula RCOOH (wherein R is a C ₁ -C ₁₀ saturated or unsaturated alkyl or aryl group having 0 to 3 substituents). The method of claim 1, wherein the hydroxy-deprotection reaction in step (b) is carried out at a temperature of -10 ~ 10 ℃ in the presence of a catalyst. The method of claim 4, wherein the reaction temperature is 0 ° C. 6. The method according to claim 4, wherein the catalyst of the deprotection reaction is potassium ethoxide, sodium ethoxide or sodium methoxide. The hydroxy protecting group (R ¹ CO) of claim 4 is α-methoxyacetyl, α-chloroacetyl, α, α'-dichloro acetyl, p -chlorobenzoyl, dichlorobenzoyl, p -bro Parent benzoyl or p -nitrobenzoyl. 8. A process according to claim 7, wherein sodium methoxide is used as a catalyst for the deprotection reaction of the hydroxy protecting group. A compound of formula

(3) Where R is an acyl group of the formula R ¹ CO, where R ¹ is hydrogen, a C ₁ -C ₇ saturated alkyl, C ₂ -C ₇ unsaturated alkyl or aryl group having 0 to 3 substituents. A process for preparing a compound of formula 3 according to claim 9 by condensation reaction of a compound of formula 6 with its primary amine groups and then with a compound of formula 2

(2)

(6) Wherein R is an acyl group of the formula R ¹ CO, wherein R ¹ is as defined above. The method of claim 10, wherein the two primary amine groups in the formula (6) is protected with a silyl group. The method of claim 10, wherein the compound in which the primary amine groups are protected is a compound of formula 6a:

(6a) Wherein R is the same as defined above. 13. The method of claim 12, wherein each R is methyl. The method of claim 10, wherein the condensation reaction is carried out at a temperature of 0 ~ 50 ℃ in the presence of Lewis acid as a catalyst. The method of claim 14, wherein the Lewis acid is trimethylsilyl trifluoromethanesulfonate (TMSOTf), boron trifluoride diethyl ether complex (BF ₃ -OEt ₂ ), aluminum chloride having 0 to 3 alkyl groups (R _n AlCl _(3-n) ), and titanium chloride having 0 to 4 alkoxy groups ((RO) _n TiCl _(4-n) ). 11. The method according to claim 10, wherein when the hydroxy protecting group of Formula 2 is p -chlorobenzoyl, the crude product obtained after completion of the reaction is obtained by precipitating with ethyl acetate, diethyl ether, toluene, t- butyl methyl ether, or the like. The precipitate is filtered, washed with diethyl ether, toluene, t- butyl methyl ether and the like to produce the compound of formula 3 in high purity.

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