JPH027318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on the formula: This invention relates to a novel method for producing an inosine derivative represented by:

The compound of formula (1) is described in U.S. Patent No. 4,011,221 and is a well-known substance, which has a cell proliferation effect and is excellent in the treatment of diseases caused by tissue damage. It is a compound useful as an effective medicine.

As a method for producing the compound of formula (1), the method described in the above-mentioned US patent specification is known, and the method described in this US patent is as shown in the following scheme.

(In the formula, R is a hypoxanthine residue, Cyst is a cysteine residue, and R ₁ and R ₂ are lower alkyl groups or aryl groups.) That is, in the above known method, when inosine is used as a starting material, In this method, prior to introducing a cysteine residue at the 5′-position, inosine
The 2′ and 3′-positions are protected in advance by replacing them with alkylidene groups, etc. (protection step), and after performing the desired reaction,
By removing the protective groups such as alkylidene groups at the 2' and 3' positions (protecting group removal step), the formula () is obtained.
The aim is to produce a compound of In this known method, the 2', 3'-positions of inosine in the above formula are replaced by
This is a roundabout method in that it requires a protection step in which protection is once introduced by introducing a protecting group and a step in which the protecting group is removed after the reaction.

As a result of intensive research into an improved method for producing the compound of formula (), the present inventors found that when inosine is directly treated with thionyl halide without special protection at the 2' and 3' positions, a novel 5'- Halogeno
It has been discovered that 5'-deoxy-2',3'-O-sulfinyl inosine can be obtained and that the compound of formula (1) can be efficiently produced using this new substance. The present invention has been made based on this knowledge.

That is, the present invention provides a general formula obtained by reacting inosine with a thionyl halide. (In the formula, X represents a halogen atom) After treating the inosinohalogen derivative represented by the general formula with a basic substance as necessary, (In the formula, M represents a hydrogen atom or an alkali metal atom) .

According to the present invention, inosine is used as a starting material, and a compound having a highly reactive halogen at the 5'-position, that is, 5'-halogeno-5 ′-deoxy-
2',3'-O-sulfininylinosine is obtained, which can be immediately converted into the target compound of formula () having a cysteine residue at the 5'-position by the following reaction, and therefore the present invention This method has extremely high production efficiency in that the number of steps is small and processing operations are simple.

The inosinohalogen derivative represented by the above general formula () is produced by reacting inosine with a thionyl halide, and in this case, the halogen of the thionyl halide can include chlorine or bromine, When thionyl chloride is used as the thionyl halide, an inosinochlor derivative is obtained, and when thionyl bromide is used, an inosinobrome derivative is obtained.

The above reaction is usually carried out in a polar organic solvent such as pyridine or hexamethylphosphoricamide for 10
0.5-2 at a temperature of ~40℃, preferably 10-20℃
It is convenient to do it on time. In addition, the amount of thionyl halide used per mole of inosine as the raw material is
It is about 5 to 7 times the molar amount. The reaction mixture thus obtained is poured into ice water under stirring, unreacted thionyl halide is decomposed by adding a weak basic substance such as sodium bicarbonate, potassium bicarbonate, etc. as necessary, and then By cooling this solution, an inosinohalogen derivative represented by the general formula () is obtained as a crystal. The inosinohalogen derivative obtained in this way is once isolated,
Alternatively, without isolation, if necessary, after treatment with a basic substance, L represented by the general formula ()
- An inosine derivative represented by the general formula () is produced by reacting with a cysteine compound.

When reacting the inosinohalogen derivative represented by the general formula () with the L-cysteine compound represented by the general formula (), alcohols such as methanol, dimethylformamide, water, etc. may be used alone or in combination with these solvents. It is convenient to use a mixed solvent and carry out the reaction at a temperature of room temperature to 100°C for 10 hours to 2 days. In addition, the usage ratio of the L-cysteine compound represented by the general formula () to 1 mole of the halogenoinosine derivative is:
The amount is 2 times the mole or more, preferably 2 to 4 times the mole.

The reaction mixture is dissolved in water as it is or after removing the precipitated crystals, neutralized with concentrated hydrochloric acid, etc.
Then, the inosine derivative represented by the formula () is obtained by cooling and collecting the precipitated crystals.

When treating inosinohalogen derivatives with a basic substance, use an aqueous solution of sodium hydroxide or potassium hydroxide as the basic substance,
It is convenient to carry out the reaction in fractions, then the reaction mixture is neutralized with a mineral acid such as hydrochloric acid and the precipitate is separated.
This product can be subjected to the next reaction with or without recrystallization.

The product thus obtained and the general formula ()
When reacting with the L-cysteine compound represented by the following, alcohols such as methanol, dimethylformamide, water, etc. are used as a solvent alone or as a mixed solvent thereof, and the reaction is carried out at room temperature or under reflux for 3 to 8 hours. Preferably, the reaction is carried out.
Liquid ammonia or the like can also be used as the solvent. In this case, the reaction is conveniently carried out at a temperature of -40 DEG to -35 DEG C. for 10 to 15 hours. The usage ratio of the L-cysteine compound represented by the general formula () is based on 1 mole of the inosinohalogen derivative.
The amount is 1.2 times or more by mole or more, preferably about 2 to 3 times by mole.

The reaction mixture thus obtained is dissolved in water as it is, or after removing the precipitated crystals,
Neutralize with concentrated hydrochloric acid, cool, and remove precipitated crystals. When liquid ammonia is used as a solvent, after the reaction is completed, ammonia is distilled off from the reaction mixture, water is added to the residue, and the same treatment as above is performed. In this way, an inosine derivative represented by formula () is obtained.

Next, the present invention will be further explained with reference to Examples.

Example 1 (a) While cooling and stirring, 15.5 g (0.13 mol) of thionyl chloride is added to 30 ml of pyridine, and 5 g (0.019 mol) of inosine is added to this solution, followed by reaction at 10-20°C for 2 hours.

After the reaction is complete, the reaction mixture is poured into ice water and left under stirring. After cooling, the precipitated crystals were collected, washed with a small amount of cold water, and dried. (Yield: 84%) was obtained as a powder crystal. This material has a melting point of 202.5-205°C (decomposed).

R _f value 0.65 (Developing solvent chloroform: methanol = 35:10) Elemental analysis value C ₁₀ H ₉ N ₄ O ₅ SCl Calculated value: C, 36.10: H, 2.73: N, 16.87:
S, 9.64: Cl, 10.65 Actual value (%): C, 36.16: H, 2.69: N,
16.73: S, 9.65: Cl, 10.39 (b) The above 5'-chloro-5'-deoxy-2',3'-O-sulfuric acid was added to 150 ml of 1 N aqueous sodium hydroxide solution at room temperature. Add 15 g of nyl inosine and stir for 10 minutes. After the reaction was completed, concentrated hydrochloric acid was added to the reaction solution under stirring to neutralize it, the reaction mixture was left to cool, and the precipitated crystals were collected, then washed with water and dried to obtain 12.4 g of crystalline product. Ta.

(c) 12 g of this crystalline product and 14.5 g (0.092 mol) of L-cysteine hydrochloride were added to 120 ml of methanol solution in which 6.7 g of sodium metal was dissolved;
Heat to reflux for 8 hours. After the reaction is complete, add 60ml of methanol and a small amount of water to the reaction mixture.
Insoluble matter is dissolved and neutralized with concentrated hydrochloric acid while stirring while cooling. Then, this mixed solution was left under cooling,
Take the precipitated crystals. When this was recrystallized from water, 6.2 g (40%) of colorless crystals of S-inosylcysteine were obtained. The ultraviolet absorption spectrum of this object is λ ^H2O _nax = 249 mμ (ε _nax = 1.30×10 ⁴ )
, and the light intensity is [α] ^27.40 _D = +11.2° (C = 1,
_H2O ).

Example 2 (a) Add 19 g (0.16 mol) of thionyl chloride to 40 ml of pyridine under cooling stirring, add 6.5 g (0.024 mol) of inosine to this solution, and add 0.5 g (0.024 mol) of inosine at 35-40°C.
Allow time to react. After the reaction was completed, the same procedure as in Example 1(a) was carried out to obtain 6.5 g of 5'-chloro-5'-deoxy-2',3'-O-sulfinyl inosine (yield 81%) as powder crystals. obtained as. The physical properties of this product were consistent with those obtained in Example 1(a).

(b) Add 2 g of the above 5'-chloro-5'-deoxy-2',3'-O-sulfininylinosine and 3 g of L-cysteine disodium salt to 30 ml of dimethylformamide, and stir at room temperature for 24 hours. Allow time to react. After the reaction is complete, the reaction mixture is left to cool, and the precipitated crystals are collected, washed with a small amount of dimethylformamide, then washed with ethanol, dissolved in 16 ml of water, and neutralized with concentrated hydrochloric acid.
After processing in the same manner as in Example 1(c),
0.48 g (21%) of colorless crystals of S-inosylcysteine were obtained. The physical properties of this product were consistent with those obtained in Example 1(c).

Example 3 (a) While cooling and stirring, 23.7 g (0.2 mol) of thionyl chloride are added to 95 ml of hexamethylphosphoricamide, and to this solution is further added 9.6 g of inosine.
(0.036 mol) was added under stirring and stirring was continued for 15 hours. After the reaction was completed, the reaction mixture was then treated in the same manner as in Example 1(a), yielding 10.1 g of
5'-chloro-5'-deoxy-2',3'-O-sulfinyl inosine (85%) was obtained as a powder crystal. The physical properties of this product were the same as those obtained in Example 1(a).

(b) 5′-chloro-5′-deoxy-2′ obtained in (a) above
，
2.4 g of 3'-O-sulfinyl inosine was treated in the same manner as in Example 1(b) to obtain 2 g of crystalline product.

(c) Add 2 g of the above crystalline product to 20 ml of methanol and water.
The suspension was suspended in 0.4 ml of a mixed solvent, 3.45 g of L-cysteine disodium salt was added thereto, and the mixture was reacted under reflux for 5 hours. After the reaction was completed, the reaction mixture was treated in the same manner as in Example 1(c), yielding 1.2 g (45%)
Colorless crystals of S-inosylcysteine were obtained. The physical properties of this product were consistent with those obtained in Example 1(c).

Example 4 (a) 25 g (0.093 mol) of inosine is suspended in 250 ml of hexamethylphosphoric triamide, and 40 ml (0.52 mol) of thionyl bromide is added dropwise thereto under stirring while cooling. After stirring for 15 hours, the reaction solution was poured into ice water and treated in the same manner as in Example 1(a) to give 5'-bromo-5'-deoxy-2' with a melting point of 205-240°C (decomposition). , 17.5 g (49.7%) of 3'-sulfinyl inosine were obtained.

R _f 0.67 (Developing solvent chloroform: methanol =
35:10) Elemental analysis value C ₁₀ H ₉ N ₄ O ₅ SBr Calculated value C, 31.4; H, 2.40; N, 14.85;
S, 8.50; Br, 21.19 Actual value C, 31.76; H, 2.39; N, 14.79;
S, 8.63; Br, 21.34 (b) 5'-bromo-5'-deoxy-2' obtained in (a) above
，
Example 1: 15 g of 3'-O-sulfinyl inosine
The same procedure as in (b) was carried out to obtain 13 g of crystalline product.

(c) Pour approximately 1000ml of liquid ammonia into a container filled with sodium hydroxide and cooled with dry ice-methanol and equipped with a drying tube.
After adding 6.6 g (0.027 mol) of L-cystine, sodium metal is gradually added until the solution becomes slightly blue in color. Next, 13 g of the crystalline product obtained in step (b) above is added to the solution that has been decolorized by adding a small amount of L-cystine, and the mixture is reacted at -40 to -35°C with stirring for 12 hours. After the reaction is complete, the reaction mixture is left overnight to evaporate the ammonia. Water is added to the residue to dissolve it, and the mixture is left to cool, and the precipitated crystals are collected, washed with cold water, and then dried. When the crystals were recrystallized from water, 4.9 g (33%) of S-inosylcysteine was obtained as colorless crystals. The physical properties of this product are as shown in Example 1(c)
The physical properties were consistent with those obtained in .

Claims (1)

[Claims] 1 General formula obtained by reacting inosine and thionyl halide (In the formula, X represents a halogen atom) After treating the inosinohalogen derivative represented by the general formula with a basic substance as necessary, (In the formula, M represents a hydrogen atom or an alkali metal atom) A formula characterized by reacting with an L-cysteine compound represented by: A method for producing an inosine derivative represented by