Preparation method of methotrexate drug intermediate

Abstract

The invention discloses a preparation method of a methotrexate drug intermediate, which comprises the following steps: by taking 2, 4, 5, 6-tetraaminopyrimidine as a raw material and tert-butyl hydroperoxide (TBHP) as an oxidant, carrying out cyclization reaction on the raw material and 1, 3-dihydroxyacetone in the presence of a catalyst, a buffering agent and a solvent, and carrying out post-treatment to obtain free alkali or acid salt of the free alkali of the methotrexate drug intermediate. The method has the advantages of simple reaction operation, mild reaction conditions, environment-friendly reaction process and high product purity and yield, and is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of pharmaceutical chemistry, and specifically relates to a method for preparing a methotrexate drug intermediate. Background Art

[0002] Pteridine ring is an important class of heterocyclic compounds, playing an important role in the fields of pharmaceutical chemistry and life sciences. For example, folic acid, which is widely present in vegetables, fruits and animal livers, is an essential substance for cell growth. It can prevent possible gene mutations and has the effect of preventing anemia in pregnant women and congenital malformations in the fetus. Methotrexate and aminopterin are immunosuppressants, commonly used in the treatment of leukemia and psoriasis. As a typical representative molecule, 2,4-diamino-6-hydroxymethylpteridine is an important intermediate for the preparation of a variety of drugs. The commonly used methods for preparing methotrexate and aminopterin in industry are as follows:

[0003] The preparation methods of 2,4-diamino-6-hydroxymethylpteridine reported in patents and literatures of various countries in the world can be summarized as follows:

[0004] Among them, patent US4077957A reported that air / oxygen was used as the oxidant. Although air is a clean and cheap oxidant, the disadvantages of this method are insufficient gas-liquid reaction contact, long reaction time, incomplete conversion, and the inability to quantify the oxidant, resulting in more side reactions and the inability to control product quality well. Patent US3989703A reported that selenium dioxide was used as an oxidant. Since the product of selenium dioxide reduction is poorly soluble in water, the risk of selenium remaining in the product is extremely high. In addition, selenium and selenium dioxide are Class 3 carcinogens, which will introduce higher EHS risks and increase a large amount of element research work, making it difficult to industrialize. Patent DE4309123A1 reports that hydrogen peroxide is used as an oxidant, but hydrogen peroxide is easily decomposed and unstable, and there are certain EHS risks. In addition, the oxidant has a strong oxidizing property, and the product is often accompanied by over-reaction byproducts, which affects the product quality.

[0005] Patent CN102952137A reports that oxygen is used as an oxidant and acidic 4A molecular sieve is also used, and the yield is improved; however, when the inventors prepared 2,4-diamino-6-hydroxymethylpteridine with reference to the patent method, they found that the yield was significantly low and the purity was low, and the problem of low reaction purity and poor control of product quality was still not solved.

[0006] Therefore, it is of great significance to invent a method for preparing 2,4-diamino-6-hydroxymethylpteridine with short reaction time, low cost, simple operation, mild reaction conditions, high yield, high purity and suitable for industrial production. Summary of the invention

[0007] The object of the present invention is to provide a method for preparing 2,4-diamino-6-hydroxymethylpteridine, an intermediate of methotrexate drugs. The method adopts an organic peroxide compound as an oxidant, has simple reaction operation, mild conditions, a short reaction time period, an environmentally friendly reaction process, improves the reaction yield and purity, and is suitable for industrial production.

[0008] To achieve the purpose of the present invention, the present invention provides the following implementation scheme: In one embodiment, a method for preparing a methotrexate drug intermediate 2,4-diamino-6-hydroxymethylpteridine of the present invention has the following reaction formula:

[0009] The method comprises subjecting a compound of formula (II) to a cyclization reaction with 1,3-dihydroxyacetone in the presence of a catalyst, an organic peroxide, a buffer and a solvent to obtain a compound of formula (I); Wherein, in the compound of formula (II), X is an inorganic acid or an organic acid, preferably, X can be selected from H2SO4, HCl, HBr or HI; when X is H2SO4, barium chloride, barium bromide or barium iodide is required for salt conversion treatment.

[0010] In the preparation method of the present invention, the organic peroxide is selected from one or more of di-tert-butyl peroxide (DTBP), dibenzoyl peroxide (BPO), diisopropylbenzene peroxide (DCP), tert-butyl hydroperoxide (TBHP), and meta-chloroperbenzoic acid (mCPBA), preferably tert-butyl hydroperoxide (TBHP).

[0011] Preferably, in the preparation method of the present invention, the molar equivalent ratio of the organic peroxide to the compound of formula (II) is 2:1 to 20:1.

[0012] Preferably, in the preparation method of the present invention, the catalyst is one or more of tryptophan, proline, threonine, serine, L-cysteine, L-pyroglutamic acid, and sodium ascorbate, preferably L-cysteine.

[0013] Preferably, in the preparation method of the present invention, the solvent is water or an organic solvent / water system, the organic solvent is one or more of methanol, ethanol, isopropanol, tert-butanol, and n-butanol, and the organic solvent is preferably tert-butanol.

[0014] Preferably, in the preparation method of the present invention, the volume mass (mL / g) ratio of the solvent to the compound of formula (II) is 50:1 to 500:1, preferably 40:1 to 300:1.

[0015] Preferably, in the preparation method of the present invention, the buffer is one or more of sodium acetate, sodium hydroxide and sodium phosphate.

[0016] Preferably, in the above-mentioned preparation method of the present invention, the molar ratio of 1,3-dihydroxyacetone to the compound of formula (II) is 1:1 to 10:1, preferably 1:1 to 5:1.

[0017] Preferably, in the preparation method of the present invention, the cyclization reaction has a reaction pH of 2 to 12, preferably 2 to 5.

[0018] Preferably, in the preparation method of the present invention, the cyclization reaction has a reaction temperature of 0 to 100°C, preferably 0 to 50°C.

[0019] Furthermore, the preparation method of the present invention can convert the compound of formula (I) into an acid salt, and the acid salt can be selected from hydrochloride, hydrobromide or iodide.

[0020] Technical effect of the present invention: The preparation method of the pteridine drug intermediate provided by the present invention adopts an organic peroxide compound as an oxidant, has the advantages of simple reaction operation, mild process, environmentally friendly reaction process, high yield (yield>80%) and good product quality (purity>95%), and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the HPLC chart of the compound of formula (I) in Example 1 Figure 2 is the HPLC chart of the compound of formula (IV) in Example 19 Implementation

[0022] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. Reagents or instruments used that do not indicate the manufacturer are conventional products that can be purchased commercially.

[0023] Example 1 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 400 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0024] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 25°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0025] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.37g of the compound of formula (I) as a brown-yellow solid. The yield was 83.5%.

[0026] The product of this embodiment was detected using an HPLC-PDA detector, and the detection chromatographic conditions were as follows: Instrument: HPLC-PDA detector (Labsolution CS workstation); Chromatographic column: SHIMADZU Shim-pack GIST C18-AQ 4.6 mm × 250 mm, 3 μm; Detection wavelength: 280nm; Injection volume: 5 μl; Flow rate: 1ml / min; Column temperature: 52°C; Sample plate temperature: 5°C; Test sample concentration: 0.2 mg / ml; Mobile phase A: 0.02 mol / L potassium dihydrogen phosphate buffer (pH 2.8); Mobile phase B: acetonitrile; Elution gradient:

[0027] Figure 1 The HPLC spectrum of the product obtained in this example shows that the HPLC purity of the product of the present invention is 96.51%.

[0028] Example 2 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0029] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 1.89 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 0°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0030] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.35g of the compound of formula (I) as a brown-yellow solid. The yield was 83.1% and the purity was 95.88%.

[0031] Example 3 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 1200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 300 mL of purified water, and collect the filtrate.

[0032] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium hydroxide solution to adjust the pH to 2.0-5.0, stir at about 50°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0033] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.30g of the compound of formula (I) as a brown-yellow solid. The yield was 81.8% and the purity was 96.13%.

[0034] Example 4 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0035] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 5.65 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium phosphate solution to adjust the pH to 2.0-5.0, stir at about 50°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0036] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.33 g of the compound of formula (I) as a brown-yellow solid. The yield was 82.5% and the purity was 96.34%.

[0037] Example 5 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 400 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0038] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone, 5.40 g of TBHP and 50 mL of tert-butanol to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 25 ° C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0039] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.28g of the compound of formula (I) as a brown-yellow solid. The yield was 81.4% and the purity was 95.93%.

[0040] Example 6 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 400 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0041] To the above filtrate, add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone, 5.40 g of TBHP and 100 mL of tert-butanol, stir for 5-10 min, add sodium hydroxide solution to adjust the pH to 2.0-5.0, stir at about 25 °C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0042] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.26g of the compound of formula (I) as a brown-yellow solid. The yield was 80.7% and the purity was 95.44%.

[0043] Example 7 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 12.75 g of 1,3-dihydroxyacetone, 7.29 g of TBHP and 300 mL of purified water into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 25°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0044] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.60g of the compound of formula (I) as a brown-yellow solid. The yield was 84.6% and the purity was 96.48%.

[0045] Example 8 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 12.75 g of 1,3-dihydroxyacetone, 7.29 g of TBHP and 1500 mL of purified water into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir at about 50°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0046] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.56 g of the compound of formula (I) as a brown-yellow solid. The yield was 83.8% and the purity was 96.11%.

[0047] Example 9 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 2.55 g of 1,3-dihydroxyacetone, 7.29 g of TBHP and 300 mL of purified water into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 0°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0048] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.48g of the compound of formula (I) as a brown-yellow solid. The yield was 82.4% and the purity was 95.87%.

[0049] Example 10 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 2.55 g of 1,3-dihydroxyacetone, 7.29 g of TBHP, 500 mL of purified water and 100 mL of tert-butanol into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 25°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0050] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.45g of the compound of formula (I) as a brown-yellow solid. The yield was 81.7% and the purity was 96.05%.

[0051] Embodiment 11 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 2.55 g of 1,3-dihydroxyacetone, 7.29 g of TBHP, 500 mL of purified water and 50 mL of tert-butanol into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 25°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0052] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.46 g of the compound of formula (I) as a brown-yellow solid. The yield was 82.0% and the purity was 96.10%.

[0053] Example 12 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 12.75 g of 1,3-dihydroxyacetone, 7.29 g of TBHP, 300 mL of purified water and 50 mL of tert-butanol into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 0°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0054] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.35g of the compound of formula (I) as a brown-yellow solid. The yield was 80.0% and the purity was 95.23%.

[0055] Example 13 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride, 4.97 g of cysteine ​​hydrochloride monohydrate, 12.75 g of 1,3-dihydroxyacetone, 7.29 g of TBHP, 300 mL of purified water and 50 mL of tert-butanol into a three-necked flask, add sodium acetate solution to adjust the pH to 2.0-3.0, stir and react at about 25°C, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0056] After the reaction, the pH was adjusted to 11-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off to obtain 4.44 g of the compound of formula (I) as a brown-yellow solid. The yield was 81.6% and the purity was 96.02%.

[0057] Embodiment 14 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 6.99 g of barium bromide dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0058] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 0°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0059] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.24g of the compound of formula (I) as a brown-yellow solid. The yield was 80.3% and the purity was 95.21%.

[0060] Embodiment 15 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 6.99 g of barium bromide dihydrate and 1200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 300 mL of purified water, and collect the filtrate.

[0061] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 50°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0062] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.25g of the compound of formula (I) as a brown-yellow solid. The yield was 80.6% and the purity was 95.11%.

[0063] Example 16 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 6.99 g of barium bromide dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0064] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone, 5.40 g of TBHP and 60 mL of tert-butanol to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 50° C. and react until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0065] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.28g of the compound of formula (I) as a brown-yellow solid. The yield was 81.2% and the purity was 95.43%.

[0066] Embodiment 17 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 8.97 g of barium iodide dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0067] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone and 5.40 g of TBHP to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 50°C to react, and control the reaction until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0068] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.28g of the compound of formula (I) as a brown-yellow solid. The yield was 81.1% and the purity was 95.33%.

[0069] Embodiment 18 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 8.97 g of barium iodide dihydrate and 200 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot, wash with 100 mL of purified water, and collect the filtrate.

[0070] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 9.45 g of 1,3-dihydroxyacetone, 5.40 g of TBHP and 60 mL of tert-butanol to the above filtrate, stir for 5-10 min, add sodium acetate solution to adjust the pH to 2.0-5.0, stir at about 50° C. and react until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0071] After the reaction, the pH was adjusted to 9-13 with 30% NaOH solution, crystallized at 15-35°C for 1h, filtered, and the filter cake was washed with an appropriate amount of purified water. The filter cake was pumped until the flow was cut off and dried under vacuum to obtain 3.25g of the compound of formula (I) as a brown-yellow solid. The yield was 80.5% and the purity was 96.04%.

[0072] Embodiment 19 5.00 g of the compound of formula (I), 50 mL of purified water and 10 mL of tert-butanol were added to a three-necked flask, 3N hydrochloric acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 4.35 g of the compound of formula (IV) as a brown-red solid, with a yield of 75.2%.

[0073] The product of this embodiment was detected using an HPLC-PDA detector, and the detection chromatographic conditions were as follows: Instrument: HPLC-PDA detector (Labsolution CS workstation); Chromatographic column: SHIMADZU Shim-pack GIST C18-AQ 4.6 mm × 250 mm, 3 μm; Detection wavelength: 280nm; Injection volume: 5 μl; Flow rate: 1ml / min; Column temperature: 52°C; Sample plate temperature: 5°C; Test sample concentration: 0.2 mg / ml; Mobile phase A: 0.02 mol / L potassium dihydrogen phosphate buffer (pH 2.8); Mobile phase B: acetonitrile; Elution gradient:

[0074] Figure 2The HPLC spectrum of the product obtained in this example shows that the HPLC purity of the product of the present invention is 97.39%.

[0075] Embodiment 20 5.00 g of the compound of formula (I), 50 mL of purified water and 20 mL of tert-butanol were added to a three-necked flask, 3N hydrochloric acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 4.31 g of the compound of formula (IV) as a brown-red solid, with a yield of 74.4% and a purity of 97.22%.

[0076] Embodiment 21 5.00 g of the compound of formula (I), 50 mL of purified water and 50 mL of tert-butanol were added to a three-necked flask, 3N hydrochloric acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and 4.07 g of the compound of formula (IV) was dried under vacuum to obtain a brown-red solid with a yield of 70.3% and a purity of 97.10%.

[0077] Embodiment 22 5.00 g of the compound of formula (I) and 50 mL of purified water were added to a three-necked flask, 3N hydrochloric acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 4.26 g of the compound of formula (IV) as a brown-red solid, with a yield of 73.6% and a purity of 97.28%.

[0078] Embodiment 23 5.00 g of the compound of formula (I), 50 mL of purified water and 10 mL of tert-butanol were added to a three-necked flask, 3N hydrobromic acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 5.10 g of the compound of formula (IV) as a brown-red solid, the yield was 73.6%, and the purity was 97.14%.

[0079] Embodiment 24 5.00 g of the compound of formula (I) and 50 mL of purified water were added to a three-necked flask, 3N hydrobromic acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 5.02 g of the compound of formula (IV) as a brown-red solid, with a yield of 70.7% and a purity of 97.23%.

[0080] Embodiment 25 5.00 g of the compound of formula (I), 50 mL of purified water and 10 mL of tert-butanol were added to a three-necked flask, 3N hydroiodic acid was added dropwise, the pH was adjusted to 1-2, crystallization was carried out at room temperature for 1-2 hours, suction was filtered, the filter cake was washed with an appropriate amount of purified water, the flow was pumped until it stopped, and vacuum dried to obtain 5.03 g of the compound of formula (IV) as a brown-red solid, the yield was 60.5%, and the purity was 95.61%.

[0081] Comparative Example 1 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 250 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot and collect the filtrate.

[0082] The filtrate was added to a solution of 3.70 g of cysteine ​​hydrochloride monohydrate, 5.65 g of 1,3-dihydroxyacetone, 4N sodium acetate and 250 mL of purified water, and the mixture was stirred with air at about 25° C. The reaction was controlled until the reaction of 2,4,5,6-tetraaminopyrimidine was completed.

[0083] After the reaction, the reaction solution was placed in a refrigerator at 2-8°C for 12 hours, filtered, and the filter cake was washed with appropriate amounts of purified water, ethanol, and ether in sequence, and the filter cake was pumped until the flow was cut off, and dried under vacuum to obtain 2.83 g of the compound of formula (I) as a yellow solid with a yield of 70.15% and a purity of 73.56%.

[0084] Comparative Example 2 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 250 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot and collect the filtrate.

[0085] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 5.65 g of 1,3-dihydroxyacetone and 250 mL of purified water to the above filtrate, and then add 11.32 g of 30% hydrogen peroxide. Stir and react at about 25° C. until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0086] After the reaction, the reaction solution was placed in a refrigerator at 2-8°C for 12 hours, filtered, and the filter cake was washed with appropriate amounts of purified water, ethanol, and ether in sequence, and the flow was stopped. The solution was dried under vacuum to obtain 2.04 g of the compound of formula (I) as a yellow solid with a yield of 50.48% and a purity of 60.67%.

[0087] Comparative Example 3 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine sulfate, 5.13 g of barium chloride dihydrate and 250 mL of purified water into a three-necked flask, heat to 80-90 °C and react for 15-30 min. When the temperature drops to 40-50 °C, filter while hot and collect the filtrate.

[0088] Add 3.70 g of cysteine ​​hydrochloride monohydrate, 5.65 g of 1,3-dihydroxyacetone and 250 mL of purified water to the above filtrate, and then add 6.33 g of tin dioxide. Stir and react at about 25° C. until the reaction of 2,4,5,6-tetraaminopyrimidine is completed.

[0089] After the reaction, the reaction solution was placed in a refrigerator at 2-8°C for 12 hours, filtered, and the filter cake was washed with appropriate amounts of purified water, ethanol, and ether in sequence, and the flow was stopped. The solution was dried under vacuum to obtain 2.94 g of the compound of formula (I) as a yellow solid with a yield of 72.8% and a purity of 75.68%.

[0090] Comparative Example 4 Add 5.00 g of 2,4,5,6-tetraaminopyrimidine hydrochloride and 100 mL of a mixed solution of methanol and water (v:v=1:1) into a three-necked flask, stir to dissolve, add 8.75 g of acidic 4A molecular sieves, stir under air at room temperature, and react for 12 h.

[0091] After the reaction, the molecular sieves were removed by filtration, the pH of the filtrate was adjusted to 8 with sodium bicarbonate, and the mixture was filtered under reduced pressure. The filter cake was collected and dried under vacuum to obtain 4.08 g of the compound of formula (I) as a brown-yellow solid with a yield of 75.0% and a purity of 50.39%.

[0092] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the protection scope of the present invention. A person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A method for preparing 2,4-diamino-6-hydroxymethylpteridine, an intermediate of methotrexate drugs, wherein the reaction formula is as follows: The method comprises subjecting a compound of formula (II) to a cyclization reaction with 1,3-dihydroxyacetone in the presence of a catalyst, an organic peroxide, a buffer and a solvent to obtain a compound of formula (I); in, In the compound of formula (II), X is an inorganic acid or an organic acid, preferably, X can be selected from H2SO4, HCl, HBr or HI; when X is H2SO4, barium chloride, barium bromide or barium iodide is required for salt conversion.

2. The preparation method according to claim 1, wherein the organic peroxide is selected from one or more of di-tert-butyl peroxide (DTBP), dibenzoyl peroxide (BPO), diisopropylbenzene peroxide (DCP), tert-butyl hydroperoxide (TBHP), and meta-chloroperbenzoic acid (mCPBA), preferably tert-butyl hydroperoxide (TBHP).

3. The preparation method according to claim 1 or 2, wherein the molar equivalent ratio of the organic peroxide to the compound of formula (II) is 2:1 to 20:

1.

4. The preparation method according to claim 1, wherein the catalyst is selected from one or more of tryptophan, proline, threonine, serine, L-cysteine, L-pyroglutamic acid and sodium ascorbate, preferably L-cysteine.

5. The preparation method according to claim 1, wherein the solvent is water or an organic solvent / water system, and the organic solvent is one or more of methanol, ethanol, isopropanol, tert-butanol, and n-butanol, preferably tert-butanol.

6. The preparation method according to claim 1 or 5, wherein the volume mass (mL / g) ratio of the solvent to the compound of formula (II) is 50:1-500:1, preferably 40:1-300:

1.

7. The preparation method according to claim 1, wherein the buffer is selected from one or more of sodium acetate, sodium hydroxide and sodium phosphate.

8. The preparation method according to claim 1, wherein the molar ratio of 1,3-dihydroxyacetone to the compound of formula (II) is 1:1-10:1, preferably 1:1-5:

1.

9. The preparation method according to claim 1, wherein the pH of the reaction system for the cyclization reaction is 2 to 12, preferably 2 to 5.

10. The preparation method according to claim 1, wherein the cyclization reaction has a reaction temperature of 0-100°C, preferably 0-50°C.

11. The preparation method according to any one of claims 1 to 10, further comprising converting the compound of formula (I) into an acid salt, wherein the acid salt can be selected from hydrochloride, hydrobromide or iodide.

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