Method for synthesizing 5-O-(beta-D-xylopyranosyl) gentisic acid

Abstract

The invention provides a method for synthesizing 5-O-(beta-D-xylopyranosyl) gentisic acid. The 5-O-(beta-D- According to the method, gentisic acid is taken as an initial raw material, and 5-O-(beta-D-xylopyranosyl) gentisic acid is simply prepared through four-step reaction (esterification reaction with tert-butyl alcohol, high-selectivity glycosylation reaction, trifluoroacetic acid mediated tert-butyl removal reaction and sodium methoxide catalyzed deacetylation reaction). The synthesized target product is an inhibitor of various enzymes, and has the potential of treating type II diabetes and inflammation. In addition, the bacillus amyloliquefaciens is expected to be used for agricultural production to improve the antiviral ability of crops. The synthesis method provided by the invention has the advantages of simple steps, mild reaction conditions and high synthesis efficiency, and has positive effects in the fields of biological medicines, medicine synthesis and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing 5-O-(β-D-xylopyranosyl)gentisic acid. Background Art

[0002] 5-O-(β-D-xylopyranosyl)gentisic acid (CAS registration number 849586-74-9) is an important bioactive substance. It has significant inhibitory activities against α-amylase and α-glucosidase, and has application prospects for the treatment of type II diabetes (S.R. Shivanagoudra, W.H. Perera, J.L.G. Perez, Athrey, Y. Sun, C.S. Wu, G.K. Jayaprakasha, B.S. Patil, Bioorgan. Med. Chem. 2019, 27, 3097-3109). It can also inhibit the release of elastase and acetylcholinesterase, and has important research value in the development of anti-inflammatory drugs (S.-H. Lam, Y.-C. Li, P.-C. Kuo, T.-L. Hwang, M.-L. Yang, C.-C. Wang, J.T.C. Tzen, Molecules 2019, 24, 1371; M.M.F. Queiroz, E.F. Queiroz, M.L. Zeraik, S.N. Ebrahimi, L. Marcourt, M. Cuendet, I. Castro-Gamboa, M. Hamburger, V. da Silva Bolzani, J.-L. Wolfender, J. Nat. Prod. 2014, 77, 650-656; Y. Liu, R. Yang, H. Zou, Z. Xu, J. Pan, J. Wu, W. Guan, Z. Hao, A.M. Algradi, H. Kuang, B. Yang, Nat. Prod. Res. 2024, 38, 1007-1015). In addition, there are literatures showing that higher concentrations of 5-O-(β-D-xylopyranosyl)gentisic acid accumulate in virus-infected tomatoes and cucumbers, indicating that this compound may play an important role in the plant defense response system (J. Fayos, J.M. Bellés, M.P. López-Gresa, J. Primo, V. Conejero, Phytochemistry 2006, 67, 142-148), and is expected to be applied in agricultural production to enhance the antiviral ability of crops.

[0003] So far, there have been nearly 20 literature reports on the biological activity of 5-O-(β-D-xylopyranosyl)gentisic acid, but its acquisition can only rely on extraction from plants (X. Ye, W. Tian, G. Wang, X. Zhang, M. Zhou, D. Zeng, X. Liu, X. Yao, Y. Zhang, H. Chen. J. Agric. Food Chem. 2020, 68, 4196–4204), and there is no literature report on its chemical synthesis.

[0004] The present invention aims to provide a simple and efficient method for synthesizing 5-O-(β-D-xylopyranosyl)gentisic acid. Summary of the Invention

[0005] As shown in Reaction Scheme 1, the present invention uses gentisic acid shown in Formula 1 as the starting material and undergoes four steps of reaction to prepare the target product 5-O-(β-D-xylopyranosyl)gentisic acid shown in Formula 6. The raw materials and reagents used in the present invention can be directly purchased.

[0006]

[0007] The technical solution of the present invention is as follows:

[0008] Step 1: Using gentisic acid shown in Formula 1 as the raw material, it undergoes an esterification reaction with tert-butanol ( t BuOH) to synthesize tert-butyl gentisate (Formula 2).

[0009] Step 2: Tert-butyl gentisate (Formula 2) reacts with tri-O-acetyl-β-bromo-D-xylopyranose (Formula 3) under the action of a base to form 5-O-(tri-O-acetyl-β-D-xylopyranosyl)tert-butyl gentisate shown in Formula 4.

[0010] Step 3: The intermediate shown in Formula 4 is deprotected by tert-butyl in trifluoroacetic acid to form the intermediate 5-O-(tri-O-acetyl-β-D-xylopyranosyl)gentisic acid shown in Formula 5.

[0011] Step 4: The intermediate shown in Formula 5 is deacetylated under the catalysis of sodium methoxide and treated with acidic DOWEX cation exchange resin to form the target product 5-O-(β-D-xylopyranosyl)gentisic acid shown in Formula 6.

[0012] In the above preparation method, in Step 1, the esterification reaction occurs under the action of carbonyldiimidazole (CDI), and 1,8-diazabicyclo[5.4.0]undec-7-ene, a strong base, needs to be added to the reaction system.

[0013] In the above preparation method, in step 2, the solvents usually used are ethyl acetate, acetonitrile, chloroform, dichloromethane, 1,2-dichloroethane, ether, tetrahydrofuran, 1,4-dioxane, toluene, chlorobenzene or a mixture thereof. The preferred solvents are acetonitrile or dichloromethane.

[0014] In the above preparation method, in step 2, the bases usually used are lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate or a mixture thereof. The preferred base is potassium carbonate.

[0015] In the above preparation method, in step 2, the amount of triacetyl-β-bromo-D-xylopyranose is 1 to 10 molar equivalents, preferably 1.5 molar equivalents, relative to tert-butyl gentisate. The amount of the base is 1 to 10 molar equivalents relative to tert-butyl gentisate.

[0016] In the above preparation method, in step 3, trifluoroacetic acid is used as the acid and dichloromethane is used as the solvent, and the mixture is heated under reflux. Among them, the amount of trifluoroacetic acid is 4 to 50 molar equivalents, preferably 20 molar equivalents.

[0017] In the above preparation method, step 4 is a one-pot synthesis, which is specifically divided into two operations: first, the acetyl group is removed in a methanol solution of sodium methoxide, and then acidic DOWEX cation exchange resin is added. Among them, the amount of sodium methoxide is 0.1 to 20 molar equivalents, and the amount of DOWEX cation exchange resin is 1 to 100 mass equivalents.

[0018] Advantages and positive effects of the present invention:

[0019] 5-O-(β-D-xylopyranosyl)gentisic acid prepared by the present invention is an important bioactive substance. As an α-amylase and α-glucosidase inhibitor, it has the application prospect of treating type II diabetes; as an elastase and acetylcholinesterase inhibitor, it has the application prospect of treating inflammation. In addition, it is also expected to be used in agricultural production to improve the antiviral ability of crops. The present invention provides for the first time a synthesis method of 5-O-(β-D-xylopyranosyl)gentisic acid, which has a short synthesis route, high synthesis efficiency, simple operation, is suitable for large-scale preparation, and has high application value. Detailed implementation mode

[0020] The present invention will be further described below by way of examples, and the present invention is not limited to the scope of the described examples.

[0021] Step 1

[0022] Synthesis of tert-butyl gentisate (2)

[0023] Dissolve gentisic acid (3.00 g, 19.5 mmol) and carbonyldiimidazole (3.16 g, 19.5 mmol) in 20 mL of dry DMF and heat at 40 °C for 1 h. Subsequently, add tert-butanol (3.73 mL, 39 mmol) and DBU (2.91 mL, 19.5 mmol), and continue stirring at 40 °C for 24 h. Cool to room temperature, add 200 mL of water, and extract with ethyl acetate. The extract is dried over anhydrous sodium sulfate, concentrated, and separated by column chromatography to obtain tert-butyl gentisate (2.12 g, yield 52%).

[0024] Light yellow solid, melting point 79 - 81 °C, R f = 0.3 (PE / EtOAc = 2:1, v / v). 1 1H NMR (CDCl3, 400 MHz) 10.72 (s, 1H), 7.29 (d, J = 3.2 Hz), 7.01 (dd, J = 3.2, 8.8 Hz, 1H), 6.89 (d, J = 8.8 Hz, 1H), 5.43 (s, 1H), 1.64 (s, 9H).

[0025] Step 2 Synthesis of tert-butyl 5-O-(triacetyl-β-D-xylopyranoside)gentisate (4)

[0026] Add triacetyl bromoxylose (3,340 mg, 1.0 mmol), tert-butyl gentisate (420 mg, 2.0 mmol), and potassium carbonate (414 mg, 3.0 mmol) to a 50-mL round-bottom flask. Under nitrogen protection, add dry acetonitrile (2.5 mL). Stir at room temperature overnight, remove acetonitrile under reduced pressure, and separate by column chromatography to obtain tert-butyl 5-O-(triacetyl-β-D-xylopyranosyl)gentisate (344 mg, 74%).

[0027] According to the same procedure, using aqueous NaOH solution (4 mol / L, 4 mL) as the base, tetrabutylammonium bromide (324 mg, 1.0 mmol) as the phase transfer catalyst, and dichloromethane (4 mL) as the solvent, 298 mg of the product is obtained with a yield of 64%.

[0028] Colorless syrup, R f = 0.3 (PE:EA = 3:1, v / v), 11H NMR (400 MHz, CDCl3) δ (ppm): 10.76 (s, 1H), 7.38 (d, J = 3.0 Hz, 1H), 7.11 (dd, J = 9.0, 3.1 Hz, 1H), 6.88 (d, J = 9.0 Hz, 1H), 5.23 (t, J = 8.0 Hz, 1H), 5.14 (dd, J = 8.2, 6.3 Hz, 1H), 5.04–4.98 (m, 2H), 4.21 (dd, J = 12.0, 4.8 Hz, 1H), 3.47 (dd, J = 12.0, 8.0 Hz, 1H), 2.10 (s, 3H), 2.08 (s, 3H), 2.07 (s, 3H), 1.60 (s, 9H). 13 13C NMR (101 MHz, CDCl3) δ (ppm): 170.0, 169.8, 169.4, 169.1, 157.9, 148.5, 125.6, 118.4, 118.0, 113.7, 99.8, 83.2, 70.9, 70.3, 68.5, 61.9, 28.2, 20.8, 20.7. HRMS (ESI): m / z calcd for: C 22 H 28 NaO 11 + [M + Na] + : 491.1524, found: 491.1531.

[0029] Step 3:

[0030] Synthesis of 5-O-(triacetyl-β-D-xylopyranosyl)gentisic acid (5)

[0031] To a 50-mL round-bottom flask, add tert-butyl 5-O-(triacetyl-β-D-xylopyranosyl)gentisate (469 mg, 0.88 mmol), dry CH2Cl2 (15 mL), and trifluoroacetic acid (1.5 mL, 20 equiv.) in sequence. Reflux until the raw materials are completely consumed. Remove dichloromethane and trifluoroacetic acid under vacuum, and recrystallize with ethyl acetate and petroleum ether to obtain 5-O-(triacetyl-β-D-xylopyranosyl)gentisic acid (376 mg, 95%).

[0032] Light yellow syrup, R f = 0.2 (PE:EA:HCOOH = 30:30:1, v / v), 11H NMR (400 MHz, CDCl3) δ (ppm): 10.19 (s, 1H), 7.53 (d, J = 3.1 Hz, 1H), 7.21 (dd, J = 9.1, 3.1 Hz, 1H), 6.94 (d, J = 9.0 Hz, 1H), 5.24 (t, J = 7.8 Hz, 1H), 5.15 (t, J = 7.0 Hz, 1H), 5.07 (d, J = 6.0 Hz, 1H), 5.02 (td, J = 7.6, 4.6 Hz, 1H), 4.23 (dd, J = 12.1, 4.8 Hz, 1H), 3.52 (dd, J = 12.1, 7.8 Hz, 1H), 2.11 (s, 3H), 2.09 (s, 3H), 2.08 (s, 3H). HRMS (ESI): m / z calcd for: C 18 H 20 NaO 11 + [M+Na] + : 435.0898, found: 435.0899.

[0033] Step 4 Synthesis of 5-O-(β-D-xylopyranosyl)gentisic acid (6)

[0034] To a suspension of 5-O-(triacetyl-β-D-xylopyranoside)gentisic acid (376 mg, 0.95 mmol) in methanol (10 mL) at 0 °C was added sodium methoxide (157 mg, 2.9 mmol). After completion of the addition, the mixture was stirred at room temperature for 1 h to obtain a clear solution. Cation exchange resin DOWEX-50WX4-200 was added to the solution until the pH value of the reaction system was 3 - 4. The mixture was filtered and the filtrate was concentrated to obtain the crude product. Recrystallization from ethyl acetate gave 5-O-(β-D-xylopyranosyl)gentisic acid product (190 mg, 70% yield).

[0035] White solid, melting point 265 - 267 °C, R f = 0.3 (EA / HCOOH = 30:1, v / v). R f = 0.4 (EA / HCOOH = 5:1, v / v). 1 1H NMR (400 MHz, D2O) δ 7.53 (d, J = 3.1 Hz, 1H), 7.20 (dd, J = 8.9, 3.1 Hz, 1H), 6.91 (d, J = 8.9 Hz, 1H), 4.98–4.93 (m, 1H), 4.02 (dd, J = 11.6, 5.4 Hz, 1H), 3.76–3.67 (m, 1H), 3.60–3.50 (m, 2H), 3.45 (dd, J = 11.6, 10.5 Hz, 1H). 1313C NMR (101 MHz, D2O) δ 174.7, 155.6, 148.8, 123.4, 118.5, 118.1, 117.2, 102.1, 75.5, 72.9, 69.1, 65.2。

Claims

1. A method for synthesizing 5-O-(β-D-xylopyranosyl)gentisic acid, characterized in that, Using gentisic acid shown in Formula 1 as a raw material, through an esterification reaction with tert-butanol (Step 1), a highly selective glycosylation reaction (Step 2), a de-tert-butylation reaction (Step 3), and a deacetylation reaction catalyzed by sodium methoxide (Step 4), 5-O-(β-D-xylopyranosyl) gentisic acid shown in Formula 6 was simply prepared.

2. The method according to claim 1, wherein Using tert-butyl gentisate (Formula 2) in Step 1 as a key intermediate.

3. The method according to claim 1, characterized in that, In Step 2, tri-O-acetyl-β-bromo-D-xylopyranose (Formula 3) reacts with tert-butyl gentisate (Formula 2) under alkaline conditions to form tert-butyl 5-O-(tri-O-acetyl-β-D-xylopyranosyl) gentisate (Formula 4).

4. The method according to claim 1, characterized in that In Step 2, the solvents used are ethyl acetate, acetonitrile, chloroform, dichloromethane, 1,2-dichloroethane, diethyl ether, tetrahydrofuran, 1,4-dioxane, toluene, chlorobenzene or a mixture thereof, and the preferred solvents are acetonitrile and dichloromethane.

5. The method according to claim 1, wherein In Step 3, the reagent used is trifluoroacetic acid.

6. The method according to claim 1, wherein In Step 4, after deacetylating, the reaction system needs to be treated with an acidic cation exchange resin.

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