CN101580495A - 5-substituted phenyl-3-isoxazole carboxylic acid and ester compounds, compositions and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of medicine, and relates to 5-substituted phenyl-3-isoxazolecarboxylic acid of general formula I and its ester compounds, tautomers, pharmaceutically acceptable salts, Pharmaceutically acceptable solvates, pharmaceutically acceptable compositions containing them, and preparation methods thereof, and the present invention also relates to the use of these compounds and compositions in the preparation of medicines for treating hyperuricemia and gout. (wherein: R ¹ is independently substituted or unsubstituted linear or branched C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₃ -C ₇ cycloalkyl, C ₃ -C ₇ cycloalkene radical, aryl, aralkyl, heterocyclyl, heteroaryl, heterocyclylalkyl, heteroarylalkyl, C ₃ -C ₇ cycloalkylalkyl, aminoalkyl, an alkylaminoalkyl, Dialkylaminoalkyl, alkoxyalkyl, aryloxyalkyl, aralkoxyalkyl, perhalogenated alkyl. ^R2 is cyano, nitro, halogen, unsubstituted, monosubstituted or disubstituted Aminocarbonyl; R is a hydrogen atom or an ethyl group; A is an oxygen atom, a sulfur atom, a nitrogen atom.)

Description

5-substituted phenyl-3-isoxazole carboxylic acid and its ester compounds, composition and preparation method thereof

technical field

The invention belongs to the technical field of medicine, and relates to 5-substituted phenyl-3-isoxazole carboxylic acid and ester compounds, compositions and preparation methods thereof, in particular to esters of 5-substituted phenyl-3-isoxazole carboxylic acid Compounds, derivatives, isomers, pharmaceutically acceptable salts, pharmaceutically acceptable solvates, pharmaceutically acceptable compositions containing them and their preparation methods, and the use of these compounds in medicine.

Background technique

Gout is a group of heterogeneous metabolic diseases caused by long-term purine metabolism disorder and/or decreased uric acid excretion. Gout is the second most common metabolic disease in humans after diabetes. The clinical features of gout are hyperuricemia, recurrent acute arthritis, tophi deposition, tophi chronic arthritis and joint deformities, chronic interstitial nephritis and nephrolithiasis caused by kidney involvement. Often complicated by cardiovascular and cerebrovascular diseases and life-threatening.

The prerequisite for the onset of gout is hyperuricemia, which refers to the uric acid content in serum at 37°C (men exceed 70mg/L; women exceed 60mg/L). When this concentration is exceeded, urate can be deposited in the tissue, causing histological changes in gout. 5% to 12% of patients with hyperuricemia eventually develop into gout. Patients with hyperuricemia only have urate crystal deposition, arthritis, kidney disease, and kidney stones, which are called gout.

Xanthine oxidoreductase (Xanthine oxidoreductase, XOR) is a highly conserved molybdenum-containing protease, which can be converted into two forms in mammals, xanthine dehydrogenase (XDH) and xanthine oxidase ( Xanthine Oxidase, XO) exists, under normal circumstances, it mainly exists in the form of dehydrogenase (XDH), which is converted into oxidase (XO) through two pathways: one is the oxidation of cysteine residues on the enzyme, and FAD Around the formation of disulfide bonds, this is a reversible transformation; another irreversible transformation formed by hydrolysis of proteases such as trypsin.

Xanthine oxidase (XO) is involved in purine catabolism, catalyzing the formation of uric acid from hypoxanthine and xanthine. Since there is no uricase in the human body, it cannot convert and decompose uric acid. Therefore, when the XO activity in the body increases abnormally, a large amount of uric acid is produced. However, the solubility of uric acid in body fluids is limited. When the concentration in body fluids exceeds its saturation concentration, it is easy to precipitate and crystallize in tissues, resulting in hyperuricemia and gout. According to epidemiological data, about 10% of primary hyperuricemia and gout are mainly caused by the deficiency or activity change of purine metabolizing enzymes, and the increase of XO activity is the main factor. The XO inhibitors developed for the increase of XO activity have good application prospects in the prevention and treatment of hyperuricemia and gout.

In the prior art, there is no relevant report on 5-substituted phenyl-3-isoxazole carboxylic acid and its ester compounds, composition and preparation method.

Contents of the invention

The object of the present invention is to provide a new compound represented by general formula I, which has the function of inhibiting xanthine oxidase (XO), and can be used for preparing medicines for treating hyperuricemia and gout.

Another object of the present invention is to provide a preparation method of the novel compound represented by general formula I.

The new compound represented by the general formula I includes 5-substituted phenyl-3-isoxazole carboxylic acid and its ester compounds and derivatives, tautomers, pharmaceutically acceptable salts, and pharmaceutically acceptable solvents Compounds and pharmaceutically acceptable compositions containing them.

The compound general formula provided by the invention is as follows:

in:

^Each R is cyano, nitro, halogen, unsubstituted, monosubstituted or disubstituted aminocarbonyl;

Each R hydrogen atom or ethyl group;

Each A is an oxygen atom, a sulfur atom, an unsubstituted nitrogen atom, or a monosubstituted nitrogen atom.

Each R ¹ is optionally substituted.

Preferably, each ^R is independently substituted or unsubstituted linear or branched C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₃ -C ₇ cycloalkyl, C ₃ -C ₇ cycloalkenyl , aryl, aralkyl, heterocyclyl, heteroaryl, heterocyclylalkyl, heteroaralkyl, C ₃ -C ₇ cycloalkylalkyl, aminoalkyl, monoalkylaminoalkyl, di Alkylaminoalkyl, alkoxyalkyl, aryloxyalkyl, aralkoxyalkyl, perhalogenated alkyl.

This invention also includes the preparation method of the compound of formula I as defined above:

(1) Preparation of 5-(3-nitro-4-alkoxy)phenyl-3-isoxazolecarboxylic acid

Using 4-hydroxyacetophenone as raw material, 3-nitro-4-hydroxyacetophenone is obtained through nitration reaction, and then alkylated with halogenated hydrocarbon to obtain 3-nitro-4-alkoxyacetophenone, Condensation reaction with diethyl oxalate then produces 4-(3-nitro-4-alkoxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester, followed by hydroxylamine hydrochloride ring Synthesis of 5-(3-nitro-4-alkoxy)phenyl-3-isoxazole formic acid ethyl ester, finally through sodium hydroxide hydrolysis, a total of five steps of reaction to obtain the target compound 5-(3-nitro -4-Alkoxy)phenyl-3-isoxazolecarboxylic acid.

(2) Preparation of 5-(3-iodo-4-alkoxy)phenyl-3-isoxazolecarboxylic acid

Using 4-hydroxyacetophenone as a raw material, 3-iodo-4-hydroxyacetophenone is obtained by iodination, and then alkylated with halogenated hydrocarbons to obtain 3-iodo-4-alkoxyacetophenone, and then combined with oxalic acid di Ethyl condensation gives 4-(3-iodo-4-alkoxy)phenyl-2-hydroxy-4-oxo-2-butenoic acid ethyl ester, followed by cyclization with hydroxylamine hydrochloride to give 5-( 3-iodo-4-alkoxy)phenyl-3-isoxazolecarboxylic acid ethyl ester, finally hydrolyzed by sodium hydroxide, a total of five steps of reaction to obtain the target compound 5-(3-iodo-4-alkoxy) Phenyl-3-isoxazolecarboxylic acid.

(3) Preparation of 5-(3-cyano-4-alkoxy)phenyl-3-isoxazolecarboxylic acid

With 4-hydroxyacetophenone as raw material, 3-iodo-4-hydroxyacetophenone is obtained by iodation, and 3-iodo-4-alkoxyacetophenone is obtained by alkylation with halogenated hydrocarbon, and then cyanidated Copper is cyanided to produce 3-cyano-4-alkoxyacetophenone, which is then condensed with diethyl oxalate to produce 4-(3-cyano-4-alkoxy)phenyl-2-hydroxy- Ethyl 4-oxo-2-butenoate, followed by cyclization with hydroxylamine hydrochloride to obtain ethyl 5-(3-cyano-4-alkoxy)phenyl-3-isoxazolecarboxylate, and finally hydrogenated Sodium hydrolysis, a total of six steps to prepare 5-(3-cyano-4-alkoxy)phenyl-3-isoxazolecarboxylic acid.

A pharmaceutically acceptable salt or solvate of the obtained compound of formula I is optionally formed.

The pharmaceutically acceptable salts of the present invention are defined as follows, but not limited thereto: salts of carboxylic acid moieties, such as alkali metal salts such as Li, Na and K salts; alkaline earth metal salts such as Ca and Mg salts; organic base salts such as lysine acid, arginine, guanidine, diethanolamine, choline, tromethamine, etc.; ammonium or substituted ammonium and aluminum salts. The salts may be acid addition salts including but not limited to sulfates, nitrates, phosphates, perchlorates, borates, hydrohalides, acetates, tartrates, maleates, citrates , succinate, palmitate, mesylate, benzoate, salicylate, besylate, ascorbate, glycerophosphate, ketoglutarate, and more. Pharmaceutically acceptable solvates may be hydrates, or contain other solvents of crystallization such as alcohols.

The compound of general formula I or its pharmaceutically acceptable salt or solvate, they are selected from:

5-(3-nitro-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

5-(3-nitro-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

5-[3-nitro-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-[3-nitro-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-(3-iodo-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

5-(3-cyano-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

5-(3-cyano-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

5-[3-cyano-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-[3-cyano-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-[3-cyano-4-(4-cyano)benzyloxy]phenyl-3-isoxazolecarboxylic acid

5-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Another aspect of the present invention includes a pharmaceutical composition comprising at least one compound of general formula I, as well as its derivatives, analogs, tautomers, polymorphs, pharmaceutically acceptable salts, pharmaceutically acceptable Pharmaceutically acceptable solvates are used as active ingredients, as well as pharmaceutically acceptable carriers, diluents, and the like.

Pharmaceutical compositions containing compounds of the present invention can be prepared by conventional methods, for example as described in Remington: the Science and Practice of Pharmacy, 19th Ed., 1995. The composition can be in conventional dosage forms such as capsules, tablets, powders, solutions, suspensions, syrups, aerosols, or topical administration forms. They may contain appropriate solid or liquid carriers, or form injectable solutions or suspensions in appropriate sterile media. The composition may contain 5-20%, preferably 0.5-10% by weight of the active compound, and the balance is pharmaceutically acceptable carriers, excipients, diluents, solvents and the like.

A typical composition contains a compound of formula I or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient, which may be a carrier or diluent, or diluted by a carrier, or packed into a carrier, which may be a capsule , sachet, paper or other container form. When the carrier serves as a diluent, it can be a solid, semi-solid or liquid material, which acts as a carrier, excipient or medium for the active compound. The active compound may be absorbed as a granular solid in containers such as sachets. Some suitable carriers are water, saline solution, alcohol, polyethylene glycol, polyhydroxyethoxylated castor oil, peanut oil, coconut oil, gelatin, lactose, terra alba, sucrose, cyclodextrin, amylose, hard Magnesium sterate, talc, gelatin, agar, pectin, acacia, lower alkyl ethers of stearic acid or cellulose, silicic acid, fatty acids, fatty acid amines, fatty acid mono- and diglycerides, quaternary into tetraol fatty acid esters, polyoxyethylene, hydroxymethylcellulose and polyvinylpyrrolidone. Likewise, the carrier or diluent may include any sustained release material known in the art, such as glyceryl monostearate or glyceryl distearate, alone or mixed with a wax. The formulations may also include wetting agents, emulsifying agents, suspending agents, preservatives, sweetening agents or flavoring agents. The formulations of the present invention may be formulated so as to provide quick, sustained or delayed release of the active ingredient after administration to the patient by methods known in the art.

The pharmaceutical composition can be sterile and, if necessary, can be mixed with adjuvants, emulsifiers, buffers and (or) coloring agents, etc., as long as they do not react with the active compound.

Administration may be by any route as long as it effectively delivers the active drug to the appropriate or desired active site, such as oral, nasal, transdermal, pulmonary, or parenteral, such as rectal, depot, subcutaneous, Intravenous, intraurethral, intramuscular, intranasal, ophthalmic solutions or ointments, preferably by the oral route.

If a solid carrier is used for oral administration, the preparation can be compressed into tablets, or placed in a capsule in powder or pellet form, or presented as a troche or lozenge. If a liquid carrier is used, the preparation may be a syrup, emulsion, soft gelatin capsule or sterile injectable solution, such as an aqueous or non-aqueous liquid suspension or solution.

For intranasal administration, the formulations may contain a compound of formula I dissolved or suspended in a liquid carrier, especially an aqueous carrier, and administered as an aerosol. The carrier may contain additives including solubilizers such as propylene glycol, surfactants, absorption enhancers such as lecithin (phosphatidylcholine) or cyclodextrin, or preservatives such as parabens.

For parenteral administration, particularly suitable are injection solutions or suspensions, preferably aqueous solutions of the active compound in polyhydroxylated castor oil.

Tablets, dragees or capsules with talc and/or carbohydrate carriers or binders or the like are particularly suitable for oral administration. Preferably, carriers for tablets, dragees or capsules include lactose, corn starch and/or potato starch. Syrups or elixirs may be used when sugar-added vehicles are available.

A typical tablet, which may be prepared by conventional tableting techniques, may contain:

core:

Active compound (free compound or its salt) 5.0mg

Colloidal silicon dioxide (KCrOSil) 1.5mg

Micro & Cellulose (AVicel) 70.0mg

Modified cellulose gum (Ac-Di-Sol) 7.5mg

Magnesium Stearate Adequate amount (ad.)

Coating layer:

HPMC About 9.0mg

^* Mywacett 9-40T about 0.9mg

^* Phenylated monoglycerides are used as plasticizers for film coatings

In the present invention, the preparation method of the compound of general formula I or its composition is simple and feasible, and the product can be used as an XO inhibitor for the treatment and/or prevention of hyperuricemia and gout.

Detailed ways:

The present invention is explained in detail by the following examples, which are only illustrative and in no way intended to limit the scope of the present invention.

Example 1

Preparation of 5-(3-nitro-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-nitro-4-hydroxyacetophenone

Dissolve p-hydroxyacetophenone (15.00g, 110.00mmol) in glacial acetic acid (40mL), stir at 45°C, slowly add concentrated nitric acid (10.5mL, 110.00mmol) dropwise, control the reaction temperature at 50°C-60°C, After dropping, continue to stir for 0.5h. The reaction solution was poured into a mixture of ice and water, a yellow solid precipitated out, filtered with suction, dried naturally at room temperature, and then recrystallized with absolute ethanol to obtain 10.50 g of yellow crystals, yield 52.6%, m.p.131.0-132.6°C.

(2) Preparation of 3-nitro-4-isobutoxyacetophenone

Add 3-nitro-4-hydroxyacetophenone (15.80 g, 87.30 mmol), anhydrous potassium carbonate (42.20 g, 306.00 mmol), DMF (150.0 mL), PEG-400 (4.0 mL) to a 250 mL round bottom In the flask, after stirring at 80° C. for 20 min, bromoisobutane (41.60 g, 306.00 mmol) was added, and the reaction was continued at this temperature for 7 h. After the reaction was completed, the reaction solution was poured into water (400 mL), extracted with dichloromethane (3×80 mL), the combined organic layers were washed twice with 3% KOH aqueous solution, and then dried over anhydrous sodium sulfate for 6 h. Filtrate, evaporate the solvent under reduced pressure, add water (100mL), a solid substance precipitates out, filter with suction, wash with water, and dry naturally at room temperature to obtain 12.10 g of a dark yellow solid, yield 58.4%, m.p.64.4-66.4°C.

(3) Preparation of 4-(3-nitro-4-isobutoxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.31g, 13.40mmol), dissolve it with absolute ethanol (15mL) to make sodium alkoxide, and add diethyl oxalate (1.78g, 12.20mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 25ml of dry THF solution of 3-nitro-4-isobutoxyacetophenone (2.90g, 12.20mmol) was slowly added dropwise to the above-prepared mixed solution, and the dropwise addition was completed for about 1h, and then in Stirring was continued at this temperature for 1 h, then transferred to room temperature and stirred for 4 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (80 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from absolute ethanol to obtain 2.30 g of a white flaky crystal product with a yield of 55.8%. m.p.102.5-104.1°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 15.14(s, 1H), 8.48(d, 1H, J=2.4), 8.17(dd, 1H, J=2.4, J=9.0), 7.16(d, 1H , J=9.0), 7.02 (s, 1H), 4.42 (m, 2H), 3.96 (d, 2H)), 2.20 (m, 1H), 1.43 (t, 3H), 1.08 (d, 6H).

(4) Preparation of ethyl 5-(3-nitro-4-isobutoxy)phenyl-3-isoxazolecarboxylate

In a 100ml round bottom flask, add 4-(3-nitro-4-isobutoxy)phenyl-2-hydroxy-4-oxo-2-butenoic acid ethyl ester (2.00g, 5.93mmol), hydrochloric acid Hydroxylamine (0.46g, 5.93mmol) and absolute ethanol (60ml) were refluxed for 6h. After the reaction was completed, 1/3 of the volume of the solvent was evaporated under reduced pressure, crystallized by cooling at room temperature, suction filtered, washed with absolute ethanol, and dried to obtain 1.60 g of a white crystalline solid with a yield of 80.7%.

m.p.134.8-136.1°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.27 (d, 1H, J=2.2), 7.96 (dd, 1H, J=2.2, J=8.8), 7.19 (d, 1H, J=8.8), 6.91 (s, 1H), 4.48 (m, 2H), 3.94 (d, 2H), 2.19 (m, 1H), 1.45 (t, 3H), 1.08 (d, 6H).

(5) Preparation of 5-(3-nitro-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-(3-nitro-4-isobutoxy)phenyl-3-isoxazolecarboxylate (0.80g, 2.33mmol), 1M sodium hydroxide (23.3ml, 23.30 mmol) aqueous solution and tetrahydrofuran (10ml), heated to reflux for 2h. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a light yellow solid. Recrystallized from anhydrous methanol to obtain 0.30 g of pale yellow needle crystals, yield 41.0%, m.p.174.6-175.9°C.

MS: m/z 260.9[M-CO ₂ -H] ^- , 307.2[M+H] ⁺ , 329.2[M+Na] ⁺ , 345[M+K] ⁺ .

IR (cm ^-1 ): 3453, 2964, 1720, 1624, 1531, 1498, 1447, 1384, 1397, 1351, 1286, 1167, 1001, 920, 762.

¹ H-NMR (300MHz, DMSO) δppm: 14.12(s, 1H), 8.46(d, 1H, J=2.2), 8.19(dd, 1H, J=2.2, J=8.8), 7.55(d, 1H, J=9), 7.48 (s, 1H), 4.04 (d, 2H), 2.06 (m, 1H), 0.99 (d, 6H).

¹³ C-NMR (300MHz, DMSO) δppm: 168.84, 160.72, 157.97, 152.79, 139.86, 131.47, 122.39, 118.62, 116.01, 101.17, 75.52, 27.68, 18.74.

Example 2

Preparation of 5-(3-nitro-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-nitro-4-hydroxyacetophenone

Concrete operation refers to (1) in embodiment 1

(2) Preparation of 3-nitro-4-benzyloxyacetophenone

In a 250ml round bottom flask was added 3-nitro-4-hydroxyacetophenone (5.00g, 27.60mmol), anhydrous potassium carbonate (11.40g, 82.90mmol), potassium iodide (0.27g, 1.38mmol) and DMF (50mL ), after stirring at 65°C for 20min, benzyl chloride (6.4mL, 55.20mmol) was added, and the reaction was continued at this temperature for 3h. Then the reaction solution was poured into water (300mL), the solid was precipitated, and the crude product was obtained by suction filtration, which was recrystallized from ethyl acetate to obtain 5.00g of light yellow crystals, yield 66.8%, m.p.132.7-134.7°C.

(3) Preparation of 4-(3-nitro-4-benzyloxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.19g, 8.12mmol), dissolve it with absolute ethanol (15mL) to make sodium alkoxide, and add diethyl oxalate (1.19g, 8.12mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 25ml of dry THF solution of 3-nitro-4-benzyloxyacetophenone (2.00g, 7.38mmol) was slowly added dropwise to the above-prepared mixed solution, and the dropwise addition was completed in about 1h. Stirring was continued for 1 h, then transferred to room temperature and stirred for 4 h. After the reaction was completed, the solvent was distilled off under reduced pressure, water (60 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from absolute ethanol to obtain 1.50 g of pale yellow flaky crystals with a yield of 36.5%. m.p.116.4-117.4°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 15.00(s, 1H), 8.49(d, 1H, J=2.3), 8.15(dd, 1H, J=2.3, J=8.9), 7.36-7.47(m , 4H+1H), 7.24 (d, 1H, J=8.9), 7.01 (s, 1H), 5.35 (s, 2H), 4.41 (m, 2H), 1.42 (t, 3H).

(4) Preparation of ethyl 5-(3-nitro-4-benzyloxy)phenyl-3-isoxazolecarboxylate

Add 4-(3-nitro-4-benzyloxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (0.70g, 1.85mmol), hydroxylamine hydrochloride in a 100ml round bottom flask (0.13g, 1.85mmol) and absolute ethanol (20ml), reflux for 2h. After the reaction was completed, 1/3 of the volume of the solvent was evaporated under reduced pressure, crystallized by cooling at room temperature, suction filtered, washed with absolute ethanol, and dried to obtain 0.60 g of a white crystalline solid with a yield of 86.4%, m.p.171.8-173.0°C.

(5) Preparation of 5-(3-nitro-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-(3-nitro-4-benzyloxy)phenyl-3-isoxazolecarboxylate (0.60g, 1.72mmol), 1M sodium hydroxide (17.2ml, 17.20mmol) in a 50ml round bottom flask ) aqueous solution and 10ml tetrahydrofuran, heated to reflux for 2h. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a light yellow solid. Glacial acetic acid was recrystallized to obtain 0.37 g of pale yellow needle crystals, yield 67.0%, m.p.189.6-191.5°C.

IR (cm ^-1 ): 3453, 2926, 1711, 1625, 1531, 1496, 1445, 1385, 1356, 1301, 1268, 1171, 1017, 937, 820, 744.

¹ H-NMR (300MHz, DMSO) δppm: 12.10(s, 1H), 8.47(d, 1H, J=2.1), 8.22(dd, 1H, J=2.1, J=8.7), 7.64(d, 1H, J=8.7), 7.36-7.49 (m, 5H+1H), 5.42 (s, 2H).

Example 3

Preparation of 5-[3-nitro-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-nitro-4-hydroxyacetophenone

Concrete operation refers to (1) in embodiment 1

(2) Preparation of 3-nitro-4-(4-methyl)benzyloxyacetophenone

In a 250ml round bottom flask were added 3-nitro-4-hydroxyacetophenone (5.00g, 27.60mmol), anhydrous potassium carbonate (11.40g, 82.90mmol), potassium iodide (0.30g, 1.38mmol) and DMF (50mL ), after stirring at 65°C for 20min, 4-methylbenzyl chloride (7.80g, 55.20mmol) was added, and the reaction was continued at this temperature for 3h. Then the reaction liquid was poured into water (300mL), the solid was precipitated, and the crude product was obtained by suction filtration. Recrystallized from ethyl acetate to obtain 5.20g of yellow crystals, yield 66.0%, m.p.108.8-110.8°C.

¹ H-NMR (300 MHz, CDCl ₃ ) δppm: 8.40 (d, 1H, J=2.1)), 8.20 (dd, 1H, J=2.1, J=9.0), 7.56 (d, 1H, J=9.0), 7.35 (d, 2H, J = 7.8), 7.22 (d, 2H, J = 8.1), 5.37 (s, 2H), 2.58 (s, 3H), 2.31 (s, 3H).

(3) Preparation of 4-[3-nitro-4-(4-methyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.44g, 19.30mmol), dissolve it with absolute ethanol (10mL) to make sodium alkoxide, and add diethyl oxalate (2.80g, 19.30mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 3-nitro-4-(4-methyl)benzyloxyacetophenone (5.00g, 17.50mmol) in 40ml of dry THF solution was slowly added dropwise to the above-prepared mixed solution for about 0.5h After the dropwise addition, continue to stir at this temperature for 1 h, then transfer to room temperature and stir for 4 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (80 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from ethyl acetate to obtain 2.80 g of brown crystals, the yield was 41.5%, m.p.109.4- 111.2°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.24(s, 1H), 8.03(d, 1H, J=8.6), 7.44(d, 2H, J=7.7), 7.35(d, 2H, J=7.8) , 7.21(d, 2H, J=7.8), 6.25(s, 1H), 5.29(s, 2H), 4.07-4.13(m, 2H), 2.31(s, 3H), 1.19-1.26(m, 3H) .

(4) Preparation of ethyl 5-[3-nitro-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-nitro-4-(4-methyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (2.50g, 6.49mmol), hydroxylamine hydrochloride (0.45g, 6.49mmol) and absolute ethanol (50ml), reflux for 1h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and recrystallize from acetonitrile to obtain 1.79 g of white crystalline solid, yield 72.0%, m.p.189.0-189.7°C.

¹ H-NMR (300 MHz, DMSO) δppm: 8.49 (d, 1H, J=2.1), 8.21 (dd, 1H, J=8.7, J=2.1), 7.63 (d, 1H, J=8.7), 7.57 ( s, 1H), 7.35(d, 2H, J=8.1), 7.22(d, 2H, J=7.8), 5.36(s, 2H), 4.40(m, 2H), 2.31(s, 3H), 1.34( t, 3H).

(5) Preparation of 5-[3-nitro-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-nitro-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylate (1.00g, 2.62mmol), 1M sodium hydroxide in a 50ml round bottom flask (26.2ml, 26.20mmol) aqueous solution and 15ml tetrahydrofuran, heated to reflux for 2h. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a light yellow solid. Recrystallized from anhydrous methanol to obtain 0.57 g of light yellow powder, yield 61.0%, m.p.173.2-174.7°C.

IR (cm ^-1 ): 3511, 3139, 2920, 1725, 1624, 1596, 1531, 1449, 1384, 1354, 1277, 1173, 996, 922, 827, 763.

¹ H-NMR (300MHz, DMSO) δppm: 8.47(d, 1H, J=2.1, 8.20(dd, 1H, J=8.8, J=2.3), 7.62(d, 1H, J=8.9), 7.48(s , 1H), 7.35 (d, 2H, J=8.0), 7.22 (d, 2H, J=8.1), 5.36 (s, 2H), 2.31 (s, 3H).

Example 4

Preparation of 5-[3-nitro-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-nitro-4-hydroxyacetophenone

Concrete operation refers to (1) in embodiment 1

(2) Preparation of 3-nitro-4-(4-chloro)benzyloxyacetophenone

In a 250ml round bottom flask were added 3-nitro-4-hydroxyacetophenone (5.00g, 27.60mmol), anhydrous potassium carbonate (11.40g, 82.90mmol), potassium iodide (0.30g, 1.38mmol) and DMF (50mL ), after stirring at 65°C for 20min, 4-chlorobenzyl chloride (5.30g, 33.10mmol) was added, and the reaction was continued at this temperature for 3h. Then the reaction solution was poured into water (300mL), the solid was precipitated, and the crude product was obtained by suction filtration, which was recrystallized from ethyl acetate to obtain 4.50g of pale yellow crystals, yield 53.3%, m.p.118.7-120.0°C.

¹ H-NMR (300MHz, DMSO) δppm: , 8.42 (d, 1H, J=2.1), 8.22 (dd, 1H, J=2.1, J=8.8), 7.56 (d, 1H, J=8.8), 7.50 (s, 4H), 5.43 (s, 2H), 2.59 (s, 3H).

(3) Preparation of 4-[3-nitro-4-(4-chloro)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.36g, 15.50mmol), dissolve it with absolute ethanol (10mL) to make sodium alkoxide, and add diethyl oxalate (2.26g, 15.50mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 30ml dry THF solution of 3-nitro-4-(4-chloro)benzyloxyacetophenone (4.30g, 14.10mmol) was slowly added dropwise to the above-prepared mixed solution for about 0.5h After the dropwise addition, continue stirring at this temperature for 1 h, then transfer to room temperature and stir for 4 h. After the reaction was complete, the solvent was distilled off under reduced pressure, water (80 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, and the crude product was obtained by suction filtration, which was recrystallized from acetone: absolute ethanol (7:3) to obtain 2.80 g of yellow crystals, which were recovered. Rate 49.0%, m.p.130.9-132.1°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.61(s, 1H), 8.38(d, 1H, J=7.5), 7.59(d, 1H, J=7.5), 7.50(s, 4H), 7.18(s , 1H), 5.45(s, 2H), 4.32(m, 2H), 1.31(t, 3H).

(4) Preparation of ethyl 5-[3-nitro-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-nitro-4-(4-chloro)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (2.80g, 6.90mmol), hydroxylamine hydrochloride (0.53g, 7.60mmol) and absolute ethanol (50ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, and dry to obtain 2.40 g of white spongy solid, yield 86.4%, m.p.174.3-175.2°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.51(s, 1H), 8.24(dd, 1H, J=8.8, J=2.1), 7.62(d, 1H, J=8.9), 7.58(s, 1H) , 7.50 (s, 4H), 5.41 (s, 2H), 4.40 (m, 2H), 1.34 (t, 3H).

(5) Preparation of 5-[3-nitro-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-nitro-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylate (2.50g, 6.21mmol), 1M sodium hydroxide in a 50ml round bottom flask (62.0ml, 62.00mmol) aqueous solution and 20ml tetrahydrofuran, heated to reflux for 2h. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a light yellow solid. Anhydrous ethanol:THF (1:1) was recrystallized twice to obtain 0.60 g of light yellow crystals, yield 25.8%, m.p.195.5-196.9°C.

IR (cm ^-1 ): 3487, 3145, 3075, 1719, 1624, 1533, 1494, 1444, 1383, 1352, 1304, 1264, 1176, 1011, 907, 817, 766.

¹ H-NMR (300 MHz, DMSO) δppm: 8.49 (d, 1H, J=2.1), 8.23 (dd, 1H, J=2.1, J=8.8), 7.62 (d, 1H, J=8.9), 7.5 ( s, 4H+1H), 5.41 (s, 2H).

Example 5

Preparation of 5-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-nitro-4-hydroxyacetophenone

Concrete operation refers to (1) in embodiment 1

(2) Preparation of 3-nitro-4-(4-tert-butyl)benzyloxyacetophenone

In a 250ml round bottom flask was added 3-nitro-4-hydroxyacetophenone (5.00g, 27.60mmol), anhydrous potassium carbonate (9.50g, 69.10mmol), potassium iodide (0.23g, 1.38mmol) and DMF (50mL ), after stirring at 65° C. for 20 min, 4-tert-butylbenzyl chloride (8.40 g, 41.40 mmol) was added, and the reaction was continued at this temperature for 3 h. Then the reaction solution was poured into water (300mL), the solid was precipitated, and the crude product was obtained by suction filtration, which was recrystallized from absolute ethanol to obtain 5.40g of light yellow crystals, yield 59.8%, m.p.96.1-97.3°C.

¹ H-NMR (300 MHz, DMSO) δppm: 8.41 (d, 1H, J=2.3), 8.20 (dd, 1H, J=2.3, J=8.8), 7.58 (d, 1H, J=8.9), 7.44 ( d, 2H, J = 8.4), 7.39 (d, 2H, J = 8.3), 5.38 (s, 2H), 2.58 (s, 3H), 1.28 (s, 9H).

(3) Preparation of 4-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.42g, 18.20mmol), dissolve it with absolute ethanol (10mL) to make sodium alkoxide, and add diethyl oxalate (2.65g, 18.20mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 3-nitro-4-(4-tert-butyl)benzyloxyacetophenone (5.40g, 16.50mmol) in 30ml dry THF solution was slowly added dropwise to the above-prepared mixed solution, about 0.5 After adding h dropwise, continue to stir at this temperature for 1h, then transfer to room temperature and stir for 4h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (80 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from ethyl acetate to obtain 2.70 g of yellow crystals, the yield was 38.3%, m.p.128.3- 130.0°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.29(s, 1H), 8.06(s, 1H), 7.42(m, 5H), 6.45(s, 1H), 5.31(s, 2H), 4.12(m, 2H), 1.28(s, 9H), 1.23(m, 3H).

(4) Preparation of ethyl 5-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-2-hydroxy-4-oxo-2-butenoic acid ethyl ester (2.70g , 8.25mmol), hydroxylamine hydrochloride (0.63g, 9.07mmol) and absolute ethanol (50ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, and dry to obtain 2.50 g of a white flaky solid with a yield of 71.4%, m.p.165.5-166.4°C.

¹ H-NMR (300 MHz, DMSO) δppm: 8.50 (d, 1H, J=2.2), 8.23 (dd, 1H, J=8.8, J=2.2), 7.62 (d, 1H, J=8.9), 7.58 ( s, 1H), 7.50 (m, 4H), 5.37 (s, 2H), 4.40 (m, 2H), 1.32 (t, 3H).

(5) Preparation of 5-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-nitro-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylate (2.40g, 5.66mmol), 1M hydroxide Sodium (56.6ml, 56.60mmol) aqueous solution and 20ml tetrahydrofuran were heated to reflux for 2h. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a yellow solid. Recrystallized from absolute ethanol to obtain 1.40 g of yellow crystals, yield 62.5%, m.p.158.5-159.8°C.

IR (cm ^-1 ): 3458, 3143, 2962, 1732, 1625, 1596, 1532, 1449, 1384, 1357, 1284, 1173, 1088, 821, 751.

¹ H-NMR (300 MHz, DMSO) δppm: 8.47 (d, 1H, J=2.1), 8.21 (dd, 1H, J=2.1, J=8.8), 7.64 (d, 1H, J=8.9), 7.5 ( m, 4H+1H), 5.36 (s, 2H), 1.28 (s, 9H).

Example 6

Preparation of 5-(3-iodo-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Add potassium iodide (60.10g, 368.00mmol), iodine (18.70g, 73.50mmol) and water (160ml) in a 1000ml three-necked flask and stir to dissolve, then dissolve p-hydroxyacetophenone (10.00g, 73.50mmol) with 500ml of concentrated ammonia After dissolving, it was added to the above reaction solution, and reacted at room temperature for about 12 hours. After the reaction was completed, filter with suction, adjust the pH of the filtrate to 1 with concentrated hydrochloric acid, and filter with suction to obtain a yellow solid. Methanol:water (7:3) recrystallized to obtain 10.80 g of yellow solid, yield 56.1%, m.p.153.4-156°C.

(2) Preparation of 3-iodo-4-isobutoxyacetophenone

Add 3-iodo-4 hydroxyacetophenone (10.80g, 41.20mmol), anhydrous potassium carbonate (14.20g, 102.70mmol), polyethylene glycol 400 (2.0ml) and DMF (80ml) into a 250ml three-necked flask ), stirred mechanically at 60°C for 20min, then added bromoisobutane (19.60g, 144.00mmol), and continued the reaction at this temperature for 7h. After the reaction was completed, the reaction solution was poured into 400ml of water, extracted with dichloromethane (80ml×3), the organic phases were combined, washed with saturated sodium chloride solution, and dried overnight with anhydrous sodium chlorate. Filter and concentrate the filtrate to obtain a brown-yellow oil. Column chromatography separated 9.20 g of light yellow solid, yield 70.2%, m.p.50.6-51.7°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.38 (d, 1H, J=2.2), 7.91 (dd, 1H, J=2.2, J=8.6), 6.79 (d, 1H, J=8.6), 3.84 (d, 2H, J=6.3), 2.54 (s, 3H), 2.18 (m, 1H), 1.10 (d, 6H).

(3) Preparation of 4-(3-iodo-4-isobutoxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.72g, 31.10mmol), dissolve it with absolute ethanol (15mL) to make sodium alkoxide, and add diethyl oxalate (4.55g, 31.10mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 30ml of dry THF solution of 3-iodo-4-isobutoxyacetophenone (9.00g, 28.30mmol) was slowly added dropwise to the above-prepared mixed solution, and the dropwise addition was completed in about 1h. The temperature was continued to stir for 1h, then transferred to room temperature and stirred for 8h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (80 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from ethyl acetate to obtain 4.70 g of a light green solid with a yield of 39.8%, m.p.138.3 -140.0°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.23(s, 1H), 7.85(s, 1H), 7.00(d, 1H), 6.50(s, 1H), 4.16(d, 2H), 3.87(d, 2H), 2.06 (m, 1H), 1.24 (q, 3H), 1.03 (d, 6H).

(4) Preparation of ethyl 5-(3-iodo-4-isobutoxy)phenyl-3-isoxazolecarboxylate

Add 4-(3-iodo-4-isobutoxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (4.65g, 11.50mmol), hydrochloric acid in a 250ml round bottom flask Hydroxylamine (0.88g, 12.70mmol) and absolute ethanol (75ml) were refluxed for 5h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and recrystallize with absolute ethanol:ethyl acetate (2:1) to obtain 3.60 g of white powder, yield 75.5%, m.p.113.3-114.4°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.20(d, 1H, J=2.1), 7.74(dd, 1H, J=8.6, J=2.1), 4.46(q, 2H), 3.84(d, 2H ), 2.19 (m, 1H), 1.44 (t, 3H), 1.10 (d, 6H).

(5) Preparation of 5-(3-iodo-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-(3-iodo-4-isobutoxy)phenyl-3-isoxazolecarboxylate (2.54g, 6.12mmol), 1M sodium hydroxide (8.0ml, 7.96 mmol) aqueous solution, 15ml tetrahydrofuran and 20ml absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a light yellow solid. Glacial acetic acid was recrystallized to obtain 1.10 g of light yellow needle crystals, yield 46.4%, m.p.183.2-184.5°C.

IR (cm ^-1 ): 2957, 2870, 1708, 1605, 1465, 1441, 1383, 1280, 1264, 1163, 1046, 1011, 932, 807, 772.

¹ H-NMR (300MHz, DMSO) δppm: 13.85(s, 1H), 8.33(s, 1H), 7.92(d, 1H), 7.37(s, 1H), 7.11(d, 1H), 3.90(d, 2H), 2.07(m, 1H), 1.04(d, 6H).

Example 7

Preparation of 5-(3-cyano-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-isobutoxyacetophenone

Step (2) in the reference embodiment 6

(3) Preparation of 3-cyano-4-isobutoxyacetophenone

Add 3-iodo-4-isobutoxyacetophenone (5.81g, 18.30mmol), cuprous cyanide (2.63g, 29.30mmol) and DMF (50ml) into a 100ml eggplant-shaped flask, and heat to reflux for 6h . After the reaction was completed, the reaction solution was cooled slightly and poured into 400ml of water to precipitate a solid, which was allowed to stand overnight, filtered with suction, and dried naturally. Heat extraction with chloroform, distill the filtrate to remove the solvent under reduced pressure, and recrystallize from absolute ethanol to obtain 3.00 g of light yellow solid, yield 75.7%, mp 97.1-97.9°C.

¹ H-NMR (300 MHz, DMSO) δppm: 8.34 (d, 1H, J=2.2), 8.20 (dd, 1H, J=2.2, J=8.9),

7.37 (d, 1H, J=8.9), 4.03 (d, 2H, J=6.5), 2.51 (s, 3H), 2.09 (m, 1H), 1.02 (d, 6H).

(4) Preparation of 4-(3-cyano-4-isobutoxy)phenyl-2-hydroxy-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.23g, 10.12mmol), dissolve it with absolute ethanol (10mL) to make sodium alkoxide, and add diethyl oxalate (1.34g, 9.20mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 10ml of dry THF solution of 3-cyano-4-isobutoxyacetophenone (2.00g, 9.20mmol) was slowly added dropwise to the above-prepared mixed solution, and the dropwise addition was completed in about 1h. The temperature was continued to stir for 1h, then transferred to room temperature and stirred for 12h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (40 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, and recrystallized from absolute ethanol to obtain 1.54 g of a white solid with a yield of 55.2%, m.p.106.7- 107.3°C.

¹ H-NMR (300MHz, DMSO) δppm: 15.06(s, 1H), 8.23(d, 1H, J=2.2), 8.18(dd, 1HJ=2.3, J=8.9), 7.06(d, 1H, J= 8.9), 6.99 (s, 1H), 4.41 (m, 2H), 3.94 (d, 2H), 2.22 (m, 1H), 1.42 (t, 3H), 1.10 (d, 6H).

(5) Preparation of ethyl 5-(3-cyano-4-isobutoxy)phenyl-3-isoxazolecarboxylate

Add 4-(3-cyano-4-isobutoxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (1.25g, 4.12mmol), hydrochloric acid in 100ml round bottom flask Hydroxylamine (0.29g, 4.12mmol) and absolute ethanol (50ml) were refluxed for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, and dry to obtain 1.11 g of white powder, yield 85.4%, m.p.176.6-177.5°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.39(d, 1H, J=2.2), 8.21(dd, 1H, J=8.9, J=2.3), 7.51(s, 1H), 7.42(d, 1H, J=8.9), 4.39 (q, 2H), 4.02 (d, 2H), 2.09 (m, 1H), 1.34 (t, 3H), 1.02 (d, 6H).

(6) Preparation of 5-(3-cyano-4-isobutoxy)phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-(3-cyano-4-isobutoxy)phenyl-3-isoxazolecarboxylate (3.00g, 9.60mmol), 1M sodium hydroxide (12.4ml, 12.40mmol) into a 250ml round bottom flask mmol) aqueous solution, 30ml tetrahydrofuran and 25ml absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was suction filtered and washed with water to obtain a white solid. Recrystallized from anhydrous methanol to obtain 2.44 g of white powder, yield 88.7%, m.p.180.0-180.5°C.

IR (cm ^-1 ): 3543, 2964, 2228, 1730, 1618, 1495, 1451, 1385, 1397, 1302, 1264, 1177, 1123, 1015, 925, 822, 778, 758.

¹ H-NMR (300MHz, DMSO) δppm: 14.06(s, 1H), 8.36(d, 1H, J=2.1), 8.20(dd, 1H, J=8.9, J=2.1), 7.44(s, 1H) , 7.42 (d, 1H, J=8.9), 4.02 (d, 2H), 2.09 (m, 1H), 1.02 (d, 6H).

Example 8

Preparation of 5-(3-cyano-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-benzyloxyacetophenone

Add 3-iodo-4-hydroxyacetophenone (5.00g, 19.10mmol), anhydrous potassium carbonate (7.91g, 57.30mmol), polyethylene glycol 400 (2.0ml) and DMF ( 50ml), stirred mechanically at 60°C for 20min, then added benzyl chloride (4.84g, 38.20mmol), and continued the reaction at this temperature for 7h. After the reaction was completed, the reaction liquid was poured into 400ml of water, and a yellow solid was precipitated, which was recrystallized from ethyl acetate to obtain 3.00 g of light yellow powder, yield 44.7%, mp 126.0-127.3°C.

(3) Preparation of 3-cyano-4-benzyloxyacetophenone

Add 3-iodo-4-benzyloxyacetophenone (2.95g, 8.40mmol), cuprous cyanide (0.90g, 10.10mmol) and DMF (30ml) into a 100ml eggplant-shaped flask, and heat to reflux for 6h. After the reaction was completed, the reaction solution was cooled slightly and poured into 200ml of water, the solid was precipitated, left to stand overnight, filtered with suction, and dried naturally. Chloroform heat extraction, the filtrate was evaporated to remove the solvent under reduced pressure, and recrystallized from absolute ethanol to obtain 1.40 g of light yellow solid, yield 66.7%, mp 126.5-127.3 °C.

(4) Preparation of 4-(3-cyano-4-benzyloxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.37g, 16.30mmol), dissolve it with absolute ethanol (10mL) to make sodium alkoxide, and add diethyl oxalate (1.91g, 13.10mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, then 35ml of dry THF solution of 3-cyano-4-benzyloxyacetophenone (2.73g, 10.90mmol) was slowly added dropwise to the above-prepared mixed solution, and the dropwise addition was completed in about 1h. Stirring was continued for 1 h, then transferred to room temperature and stirred for 12 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (40 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, and the crude product was obtained by suction filtration, which was recrystallized from absolute ethanol: ethyl acetate (1:1) to obtain 2.00 g of a yellow solid , yield 52.3%, m.p.125.2-126.3°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.55(s, 1H), 8.35(d, 1H), 7.41(m, 7H), 7.17(s, 1H), 5.14(s, 2H), 4.31(q, 2H), 1.31(t, 3H).

(5) Preparation of ethyl 5-(3-cyano-4-benzyloxy)phenyl-3-isoxazolecarboxylate

Add 4-(3-cyano-4-benzyloxy)phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (2.00g, 5.70mmol), hydroxylamine hydrochloride in a 100ml round bottom flask (0.43g, 6.26mmol) and absolute ethanol (50ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, and dry to obtain 1.71 g of light yellow powder, yield 86.5%, m.p.184.0-184.7°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.02(d, 1H, J=2.4), 7.92(dd, 1H, J=9.0, J=2.4), 7.41(m, 5H), 7.13(d, 1H , J=9.0), 6.86 (s, 1H), 5.30 (s, 2H), 4.47 (q, 2H), 1.44 (t, 3H).

(6) Preparation of 5-(3-cyano-4-benzyloxy)phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-(3-cyano-4-benzyloxy)phenyl-3-isoxazolecarboxylate (1.70g, 4.89mmol), 1M sodium hydroxide (6.4ml, 6.40mmol) in a 100ml round bottom flask ) aqueous solution, 15ml of tetrahydrofuran and 10ml of absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was filtered with suction and washed with water to obtain a yellow solid. Glacial acetic acid was recrystallized to obtain 1.05 g of yellow powder, yield 65.5%, m.p.183.4-184.1°C.

IR (cm ^-1 ): 3423, 2225, 1708, 1616, 1490, 1455, 1385, 1295, 1261, 1179, 1121, 991, 817, 781, 742.

¹ H-NMR (300MHz, DMSO) δppm: 8.40(d, 1H, J=2.1), 8.22(dd, 1H, J=8.9, J=2.1), 7.46(m, 7H), 5.39(s, 2H) .

Example 9

Preparation of 5-[3-cyano-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-(4-methyl)benzyloxyacetophenone

Add 3-iodo-4-hydroxyacetophenone (5.00g, 19.10mmol), anhydrous potassium carbonate (7.91g, 57.30mmol), polyethylene glycol 400 (2ml) and DMF (50ml ), stirred mechanically at 60°C for 20min, then added 4-methylbenzyl chloride (5.41g, 38.20mmol), and continued the reaction at this temperature for 7h. After the reaction was completed, the reaction solution was poured into 400ml of water, and a yellow solid was precipitated, which was recrystallized from ethyl acetate to obtain 3.75g of a light yellow powder, with a yield of 53.7%, m.p.117.3-118.9°C.

¹ H-NMR (300 MHz, CDCl ₃ ) ppm: 8.40 (d, 1H, J=2.0), 7.90 (dd, 1H, J=2.0, J=8.6), 7.36 (d, 2H, J=7.9), 7.20 (d, 2H, J = 7.8), 6.86 (d, 1H, J = 8.6), 5.18 (s, 2H), 2.53 (s, 3H), 2.36 (s, 3H).

(3) Preparation of 3-cyano-4-(4-methyl)benzyloxyacetophenone

Add 3-iodo-4-(4-methyl)benzyloxyacetophenone (3.75g, 10.20mmol), cuprous cyanide (1.10g, 12.20mmol) and DMF (50ml) in a 100ml eggplant-shaped flask , Heated to reflux for 6h. After the reaction was completed, the reaction solution was cooled slightly and poured into 300ml of water, a solid was precipitated, left to stand overnight, filtered with suction, and dried naturally. Chloroform heat extraction, the filtrate was evaporated under reduced pressure to remove the solvent, and recrystallized from absolute ethanol to obtain 1.40 g of a dark yellow solid, yield 52.2%, m.p.102.9-103.8°C.

¹ H-NMR (300 MHz, CDCl ₃ ) δppm: 8.20 (d, 1H, J=2.2), 8.12 (dd, 1H, J=2.3, J=8.9), 7.35 (d, 2H, J=8.0), 7.22 (d, 2H, J = 8.0), 7.08 (d, 1H, J = 8.9), 5.28 (s, 2H), 2.58 (s, 3H), 2.38 (s, 3H).

(4) Preparation of 4-[3-cyano-4-(4-methyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.61g, 26.60mmol), dissolve it with absolute ethanol (20mL) to make sodium alkoxide, and add diethyl oxalate (3.11g, 21.30mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 3-cyano-4-(4-methyl)benzyloxyacetophenone (4.70g, 17.70mmol) in 40ml of dry THF solution was slowly added dropwise to the above-prepared mixed solution for about 1h After the addition was complete, stirring was continued at this temperature for 1 h, then transferred to room temperature and stirred for 12 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (60 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, and the crude product was obtained by suction filtration, which was recrystallized from absolute ethanol: ethyl acetate (1:1) to obtain a brownish yellow solid 4.30 g, yield 66.6%, m.p.154.2-155.4°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.55(s, 1H), 8.35(d, 1H,), 7.50(d, 1H,), 7.39(d, 1H, J=7.7), 7.23(d, 1H , J=7.7), 7.19 (s, 1H), 5.36 (s, 2H), 4.32 (q, 2H), 2.32 (s, 3H), 1.32 (t, 3H).

(5) Preparation of ethyl 5-[3-cyano-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-cyano-4-(4-methyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (4.30g, 11.80mmol), hydroxylamine hydrochloride (0.97g, 13.90mmol) and absolute ethanol (100ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and recrystallize from ethyl acetate to obtain 2.75 g of a flaky white solid, yield 63.7%, m.p.190.3-191.5°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.01 (d, 1H, J=2.2), 7.91 (dd, 1H, J=8.9, J=2.2), 7.33 (d, 2H, J=8.0), 7.21 (d, 2H, J=8.0), 7.15 (d, 1H, J=8.9), 6.86(s, 1H), 5.25(s, 2H), 4.47(q, 2H), 2.36(s, 3H), 1.45 (t, 3H).

(6) Preparation of 5-[3-cyano-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-cyano-4-(4-methyl)benzyloxy]phenyl-3-isoxazolecarboxylate (2.75g, 7.60mmol), 1M sodium hydroxide in a 100ml round bottom flask (9.1ml, 9.10mmol) aqueous solution, 15ml tetrahydrofuran and 20ml absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was suction filtered and washed with water to obtain a white solid. Anhydrous ethanol: tetrahydrofuran (4:1) was recrystallized to obtain 1.61 g of cotton flocculent crystals, yield 63.4%, m.p.194.7-195.1°C.

IR (cm ^-1 ): 3423, 2225, 1729, 1616, 1490, 1453, 1385, 1295, 1270, 1179, 1121, 985, 818, 785.

¹ H-NMR (300MHz, DMSO) δppm: 8.37(s, 1H), 8.20(d, 1H), 7.51(d, 1H), 7.41(s, 1H), 7.39(d, 2H, J=7.9), 7, 23 (d, 2H, J = 7.8), 5.33 (s, 2H), 2.31 (s, 3H).

Example 10

Preparation of 5-[3-cyano-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-(4-chloro)benzyloxyacetophenone

In a 250ml three-necked flask, add 3-iodo-4-hydroxyacetophenone (6.00g, 22.90mmol), anhydrous potassium carbonate 9.48g, 68.70mmol), polyethylene glycol 400 (2ml) and DMF (50ml) , stirred mechanically at 60° C. for 20 min, then added 4-chlorobenzyl chloride (5.54 g, 34.40 mmol), and continued the reaction at this temperature for 7 h. After the reaction was completed, the reaction solution was poured into 400ml of water, and a yellow solid was precipitated, which was recrystallized from absolute ethanol: chloroform (3:1) to obtain 6.50 g of a light yellow powder, yield 73.4%, m.p.126.5-127.7°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.40(d, 1H, J=2.1), 7.92(dd, 1H, J=2.1, J=8.6), 7.40(m, 4H), 6.85(d, 1H , J=8.6), 5.18 (s, 2H), 2.54 (s, 3H).

(3) Preparation of 3-cyano-4-(4-chloro)benzyloxyacetophenone

Add 3-iodo-4-(4-chloro)benzyloxyacetophenone (6.44g, 16.70mmol), cuprous cyanide (1.49g, 18.37mmol) and DMF (50ml) in a 100ml eggplant-shaped flask , Heated to reflux for 6h. After the reaction was completed, the reaction solution was cooled slightly and poured into 250ml of water, a solid was precipitated, left to stand overnight, filtered with suction, and dried naturally. Chloroform heat extraction, the filtrate was evaporated under reduced pressure to remove the solvent, and recrystallized from absolute ethanol to obtain 3.80 g of a light yellow solid with a yield of 79.8%, m.p.119.6-120.9°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.20(d, 1H, J=2.2), 8.12(dd, 1H, J=2.2, J=8.9), 7.39(s, 4H), 7.05(d, 1H , J=8.9), 5.26 (s, 2H), 2.57 (s, 3H).

(4) Preparation of 4-[3-cyano-4-(4-chloro)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.50g, 20.060mmol), dissolve it with absolute ethanol (20mL) to make sodium alkoxide, and add diethyl oxalate (2.33g, 16.00mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 25ml of dry THF solution of 3-cyano-4-(4-chloro)benzyloxyacetophenone (3.80g, 13.30mmol) was slowly added dropwise to the above-prepared mixed solution for about 1h After the addition was complete, stirring was continued at this temperature for 1 h, then transferred to room temperature and stirred for 12 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (40mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, and the crude product was obtained by suction filtration, which was recrystallized from absolute ethanol:ethyl acetate (1:1) to obtain a tan solid 4.60 g, yield 59.7%, m.p.132.2-133.1°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.58(s, 1H), 8.37(d, 1H), 7.52(s, 4H), 7.48(s, 1H), 7.20(s, 1H), 5.42(s, 2H), 4.32(q, 2H), 1.32(t, 3H).

(5) Preparation of ethyl 5-[3-cyano-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-cyano-4-(4-chloro)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (3.00g, 7.80mmol), hydroxylamine hydrochloride (0.64g, 9.10mmol) and absolute ethanol (70ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and recrystallize from ethyl acetate to obtain 2.30 g of a flaky white solid, yield 76.7%, m.p.175.1-175.8°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.02(d, 1H, J=2.2), 7.94(dd, 1H, J=8.9, J=2.2), 7.39(s, 4H), 7.11(d, 1H , J=8.9), 6.87 (s, 1H), 5.25 (s, 2H), 4.47 (q, 2H), 1.44 (t, 3H).

(6) Preparation of 5-[3-cyano-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-cyano-4-(4-chloro)benzyloxy]phenyl-3-isoxazolecarboxylate (2.30g, 6.01mmol), 1M sodium hydroxide in a 100ml round bottom flask (7.2ml, 7.20mmol) aqueous solution, 15ml tetrahydrofuran and 20ml absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, the mixture was suction filtered and washed with water to obtain a white solid, which was recrystallized from absolute ethanol: tetrahydrofuran (4:1) to obtain Flaky yellowish crystals 1.45g, yield 68.1%, m.p.191.5-192.3°C.

IR (cm ^-1 ): 3474, 2223, 1731, 1617, 1496, 1454, 1385, 1291, 1269, 1242, 1124, 993, 826, 747.

¹ H-NMR (300MHz, DMSO) δppm: 8.40(d, 1H, J=2.1), 8.22(d, 1H, J=8.9, J=2.1), 7.52(s, 4H), 7.50(d, 1H, J=7.9), 7, 43(s, 1H), 5.39(s, 2H).

Example 11

Preparation of 5-[3-cyano-4-(4-cyano)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-(4-cyano)benzyloxyacetophenone

In a 250ml three-necked flask, add 3-iodo-4-hydroxyacetophenone (14.00g, 53.40mmol), anhydrous potassium carbonate 21.10g, 160.03mmol), polyethylene glycol 400 (4ml) and DMF (100ml) , stirred mechanically at 60° C. for 20 min, then added 4-cyanobenzyl chloride (12.20 g, 80.20 mmol), and continued the reaction at this temperature for 7 h. After the reaction was completed, the reaction solution was poured into 500ml of water, and a yellow solid was precipitated, which was recrystallized from ethyl acetate to obtain 15.70 g of a yellow powder, with a yield of 78.5%, m.p.156.9-158.2°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.42(d, 1H, J=2.1), 7.93(dd, 1H, J=2.1, J=8.6), 7.68(m, 4H), 6.85(d, 1H , J=8.6), 5.27 (s, 2H), 2.56 (s, 3H).

(3) Preparation of 3-cyano-4-(4-cyano)benzyloxyacetophenone

Add 3-iodo-4-(4-cyano)benzyloxyacetophenone (8.00g, 21.20mmol), cuprous cyanide (2.19g, 24.40mmol) and DMF (60ml) in a 100ml eggplant-shaped flask , Heated to reflux for 6h. After the reaction was completed, the reaction solution was cooled slightly and poured into 250ml of water, a solid was precipitated, left to stand overnight, filtered with suction, and dried naturally. After thermal extraction with chloroform, the filtrate was evaporated under reduced pressure to remove the solvent, and purified by flash column (ethyl acetate as the eluent) to obtain 4.80 g of a yellow solid with a yield of 81.9%, m.p.166.7-167.9°C.

¹ H-NMR (300 MHz, CDCl ₃ ) δppm: 8.22 (d, 1H, J=2.1), 8.15 (dd, 1H, J=2.1, J=8.8), 7.73 (d, 2H, J=8.3), 7.59 (d, 2H, J=8.2), 7.04 (d, 1H, J=8.9), 5.33 (s, 2H), 2.58 (s, 3H).

(4) Preparation of 4-[3-cyano-4-(4-cyano)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.56g, 24.45mmol), dissolve it with absolute ethanol (20mL) to make sodium alkoxide, and add diethyl oxalate (2.85g, 19.50mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 45ml of dry THF solution of 3-cyano-4-(4-cyano)benzyloxyacetophenone (4.50g, 16.30mmol) was slowly added dropwise to the above-prepared mixed solution for about 1h After the addition was complete, stirring was continued at this temperature for 1 h, then transferred to room temperature and stirred for 12 h. After the reaction was completed, the solvent was evaporated under reduced pressure, water (50 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, and the crude product was obtained by suction filtration, which was recrystallized from absolute ethanol: ethyl acetate (1:4) to obtain a yellowish brown solid 2.70 g, yield 44.0%, m.p.172.8-173.7°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.57(s, 1H), 8.36(d, 1H), 7.93(d, 2H, J=8.2), 7.68(d, 2H, J=8.2), 7.48(d , 1H), 7.15(s, 1H), 5.53(s, 2H), 4.30(q, 2H), 1.31(t, 3H).

(5) Preparation of ethyl 5-[3-cyano-4-(4-cyano)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-cyano-4-(4-cyano)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester (2.70g, 7.18mmol), hydroxylamine hydrochloride (0.55g, 7.90mmol) and absolute ethanol (60ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and purify by flash column chromatography (ethyl acetate as eluent) to obtain 2.37 g of white solid, yield 88.4%, m.p.200.7-201.5°C.

¹ H-NMR (300 MHz, DMSO) δppm: 8.45 (d, 1H, J=2.2), 8.25 (dd, 1H, J=8.9, J=2.2), 7.93 (d, 2H, J=8.2), 7.68 ( d, 2H, J = 8.2), 7.52 (d, 1H, J = 8.9), 7.49 (s, 1H), 5.51 (s, 2H), 4.40 (q, 2H), 1.34 (t, 3H).

(6) Preparation of 5-[3-cyano-4-(4-cyano)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-cyano-4-(4-cyano)benzyloxy]phenyl-3-isoxazolecarboxylate (2.37g, 7.31mmol), 1M sodium hydroxide in a 100ml round bottom flask (8.8ml, 8.78mmol) aqueous solution, 15ml tetrahydrofuran and 20ml absolute ethanol were reacted at 60°C for 40min. After the reaction was complete, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 min, the mixture was filtered with suction and washed with water to obtain a yellow solid, which was recrystallized from tetrahydrofuran: dimethyl sulfoxide (1: 1). 1.54 g of yellow powder was obtained, yield 61.1%, m.p.160.3-161.0°C.

IR (cm ^-1 ): 3439, 2231, 1708, 1692, 1616, 1505, 1489, 1447, 1383, 1303, 1263, 1122, 1033, 1014, 949, 825, 782, 752.

¹ H-NMR (300MHz, DMSO) δppm: 14.10(s, 1H), 8.42(d, 1H, J=2.2), 8.23(dd, 1H, J=8.9, J=2.2), 7.93(d, 2H, J = 8.2), 7.68 (d, 2H, J = 8.2), 7.49 (d, 1H, J = 8.9), 7.44 (s, 1H), 5.50 (s, 2H).

Example 12

Preparation of 5-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

The title compound was prepared according to the method of the following scheme

(1) Preparation of 3-iodo-4-hydroxyacetophenone

Step (1) in the reference embodiment 6

(2) Preparation of 3-iodo-4-(4-tert-butyl)benzyloxyacetophenone

Add 3-iodo-4-hydroxyacetophenone (9.10g, 34.70mmol), anhydrous potassium carbonate (14.40g, 104.20mmol), polyethylene glycol 400 (4ml) and DMF (60ml ), stirred mechanically at 60°C for 20min, then added 4-tert-butylbenzyl chloride (9.50g, 52.10mmol), and continued the reaction at this temperature for 7h. After the reaction was completed, the reaction solution was poured into 500ml of water, and a yellow solid was precipitated, which was recrystallized from absolute ethanol to obtain 9.50 g of a yellow powder, with a yield of 66.9%, m.p.107.9-108.8°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.41(d, 1H, J=2.1), 7.91(dd, 1H, J=2.1, J=8.6), 7.42(s, 4H), 6.89(d, 1H , J=8.6), 5.20 (s, 2H), 2.53 (s, 3H), 1.33 (s, 9H).

(3) Preparation of 3-cyano-4-(4-tert-butyl)benzyloxyacetophenone

Add 3-iodo-4-(4-tert-butyl)benzyloxyacetophenone (7.50g, 18.40mmol), cuprous cyanide (1.81g, 20.20mmol) and DMF (50ml ), heated to reflux for 6h. After the reaction was completed, the reaction solution was cooled slightly and poured into 250ml of water, a solid was precipitated, left to stand overnight, filtered with suction, and dried naturally. After thermal extraction with chloroform, the filtrate was evaporated under reduced pressure to remove the solvent, and purified by flash column (ethyl acetate as eluent) to obtain 4.20 g of yellow solid, yield 70.9%, m.p.106.9-108.3°C.

¹ H-NMR (300MHz, CDCl ₃ ) δppm: 8.19(d, 1H, J=2.2), 8.11(dd, 1H, J=2.2, J=8.9), 7.42(m, 4H), 7.08(d, 1H , J=8.9), 5.26 (s, 2H), 2.56 (s, 3H), 1.32 (s, 9H).

(4) Preparation of 4-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-2-hydroxyl-4-oxo-2-butenoic acid ethyl ester

Weigh metal sodium (0.42g, 17.40mmol), dissolve it with absolute ethanol (15mL) to make sodium alkoxide, and add diethyl oxalate (2.03g, 13.90mmol) dropwise under the condition of mechanical stirring at -6°C to obtain a mixture solution, and then 25ml of dry THF solution of 3-cyano-4-(4-tert-butyl)benzyloxyacetophenone (3.56g, 11.58mmol) was slowly added dropwise to the above-prepared mixed solution for about 1h After the dropwise addition, continue to stir at this temperature for 1h, then transfer to room temperature and stir for 10h. After the reaction was completed, the solvent was distilled off under reduced pressure, water (60 mL) was added, the pH was adjusted to 3 with 5% dilute hydrochloric acid, the crude product was obtained by suction filtration, recrystallized with glacial acetic acid, and 1.86 g of a yellow-brown solid was obtained, the yield was 39.4%, m.p.110.9- 112.1°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.57(s, 1H), 8.36(dd, 1H), 7.52(d, 2H, J=9), 7.44(m, 4H), 7.19(s, 1H), 5.37(s, 2H), 4.32(q, 2H), 1.32(t, 3H+9H).

(5) Preparation of ethyl 5-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylate

Add 4-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-2-hydroxy-4-oxo-2-butenoic acid ethyl ester (1.50g , 3.70mmol), hydroxylamine hydrochloride (0.28g, 4.10mmol) and absolute ethanol (40ml), reflux for 2h. After the reaction was completed, crystallize by cooling at room temperature, filter with suction, wash with absolute ethanol, dry, and purify by flash column chromatography (ethyl acetate as eluent) to obtain 1.24 g of a yellow solid with a yield of 83.2%, m.p.181.3-182.2°C.

¹ H-NMR (300MHz, DMSO) δppm: 8.42(s, 1H), 8.23(d, 1H), 7.54(d, 1H+1H), 7.44(d, 4H), 5.34(s, 2H), 4.40( q, 2H), 1.33 (t, 3H+9H).

(6) Preparation of 5-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylic acid

Add ethyl 5-[3-cyano-4-(4-tert-butyl)benzyloxy]phenyl-3-isoxazolecarboxylate (1.90g, 4.70mmol), 1M hydroxide Sodium (6.1ml, 6.10mmol) aqueous solution, 15ml tetrahydrofuran and 20ml absolute ethanol were reacted at 60°C for 40min. After the reaction was completed, the solvent was evaporated under reduced pressure, a little water was added, and then the pH was adjusted to 1 with 4% dilute hydrochloric acid. After stirring for 20 minutes, suction filtration, washing with water gave a yellow solid, and recrystallization from absolute ethanol gave 1.30 g of a yellow powder. 73.5%, m.p. 165.0-166.1°C.

IR (cm ^-1 ): 3453, 3137, 2962, 2229, 1732, 1692, 1618, 1501, 1451, 1384, 1302, 1277, 1123, 995, 821, 779.

¹ H-NMR (300 MHz, DMSO) δppm: 8.39 (d, 1H, J=2.4), 8.22 (dd, 1H, J=8.9, J=2.3), 7.53 (d, 2H, J=9.0), 7.46 ( m, 4H), 7.40 (s, 1H), 5.50 (s, 2H), 1.29 (s, 9H).

Example 13

Xanthine oxidoreductase (XOD) inhibitor activity detection

(1) Experimental principle

Bovine XOD was purchased from Sigma, and XOD activity was detected using xanthine as a substrate. Observe the inhibition of the enzyme activity by the sample to evaluate the inhibitory effect of the sample. The positive reference compound used was allopurinol.

(2) Experimental method

The 200μL reaction system contains an appropriate amount of XOD, pH7.4 phosphate buffer, xanthine (SIGMA) and samples, and a blank control (without enzyme and sample) and a negative control (without sample) are set up at the same time, react at 25°C for 90min, and measure at 293nM OD value. The inhibition rate was calculated according to the OD value, and the inhibition rate=[1-(OD sample-OD blank)/(OD enzyme activity-OD blank)]×100. In the initial screening, each sample was single-concentrated with duplicate holes, and the IC ₅₀ value of the samples with an inhibition rate greater than 50% was determined. During the measurement, each sample was diluted to ten concentrations, and each concentration was set with duplicate holes. According to the inhibition rate, apply the 4 ParameterLogistic Model in the Xlfit software to calculate the IC ₅₀ .

(3) Experimental results

Determination of _IC50 values

The enzyme level test proves that the compound of the general formula I has good xanthine oxidase inhibitory activity, and has good preventive and therapeutic effects on hyperuricemia and gout.

Claims (7)

1. compound or its pharmacy acceptable salt or solvate as a general formula I

Wherein:

Each R ²For cyano group, nitro, halogen, nothing replace, the single replacement or two substituted aminocarbonyl;

Each R is hydrogen atom or ethyl;

Each A is Sauerstoffatom, sulphur atom, nitrogen-atoms;

R ¹Replace for optional.

2. compound according to claim 1, wherein each R ¹Independent C for replacement or unsubstituted straight or branched ₁-C ₁₀Alkyl, C ₂-C ₁₀Thiazolinyl, C ₃-C ₇Cycloalkyl, C ₃-C ₇Cycloalkenyl group, aryl, aralkyl, heterocyclic radical, heteroaryl, heterocyclic radical alkyl, heteroaralkyl, C ₃-C ₇Cycloalkylalkyl, aminoalkyl group, an alkylamino alkyl, dialkyl aminoalkyl, alkoxyalkyl, aryl oxide alkyl, sweet-smelling alkoxy alkyl, fully halogenated alkyl.

3, the compound of general formula I according to claim 1 and 2 or its pharmacy acceptable salt or solvate, they are selected from:

5-(3-nitro-4-isobutoxy) phenyl-3-isoxazole carboxylic acid

5-(3-nitro-4-isobutoxy) phenyl-3-isoxazole carboxylic acid ethyl ester

5-(3-nitro-4-benzyloxy) phenyl-3-isoxazole carboxylic acid

5-(3-nitro-4-benzyloxy) phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-nitro-4-(4-methyl) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-nitro-4-(4-methyl) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-nitro-4-(4-chloro) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-nitro-4-(4-chloro) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-nitro-4-(the 4-tertiary butyl) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-nitro-4-(the 4-tertiary butyl) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-(3-iodo-4-isobutoxy) phenyl-3-isoxazole carboxylic acid

5-(3-iodo-4-isobutoxy) phenyl-3-isoxazole carboxylic acid ethyl ester

5-(3-cyano-4-isobutoxy) phenyl-3-isoxazole carboxylic acid

5-(3-cyano-4-isobutoxy) phenyl-3-isoxazole carboxylic acid ethyl ester

5-(3-cyano group-4-benzyloxy) phenyl-3-isoxazole carboxylic acid

5-(3-cyano group-4-benzyloxy) phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-cyano group-4-(4-methyl) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-cyano group-4-(4-methyl) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-cyano group-4-(4-chloro) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-cyano group-4-(4-chloro) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-cyano group-4-(4-cyano group) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-cyano group-4-(4-cyano group) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester

5-[3-cyano group-4-(the 4-tertiary butyl) benzyloxy] phenyl-3-isoxazole carboxylic acid

5-[3-cyano group-4-(the 4-tertiary butyl) benzyloxy] phenyl-3-isoxazole carboxylic acid ethyl ester.

4, a kind of method for preparing the formula I compound of claim 1 or 2 definition, this method comprises:

(1) preparation of 5-(3-nitro-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid

With the 4-hydroxy acetophenone is raw material, through nitration reaction make 3-nitro-4-hydroxy acetophenone, make 3-nitro-4-alkoxy benzene ethyl ketone with the halohydrocarbon hydrocarbonylation again, make 4-(3-nitro-4-alkoxyl group) phenyl-2-hydroxyl-4-oxo-2-butylene acetoacetic ester with oxalic acid diethyl ester generation condensation reaction then, then get 5-(3-nitro-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid ethyl ester with the oxammonium hydrochloride cyclization, after sodium hydroxide hydrolysis, the reaction of five steps makes target compound 5-(3-nitro-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid altogether;

(2) preparation of 5-(3-iodo-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid

With the 4-hydroxy acetophenone is raw material, through iodo make 3-iodo-4-hydroxy acetophenone, get 3-iodine 4-alkoxy benzene ethyl ketone with the halohydrocarbon hydrocarbonylation again, get 4-(3-iodo-4-alkoxyl group) phenyl-2-hydroxyl-4-oxo-2-butylene acetoacetic ester with the oxalic acid diethyl ester condensation then, then make 5-(3-iodo-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid ethyl ester with oxammonium hydrochloride generation ring-closure reaction, after sodium hydroxide hydrolysis, the reaction of five steps makes target compound 5-(3-iodo-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid altogether;

(3) preparation of 5-(3-cyano group-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid

With the 4-hydroxy acetophenone is raw material, through iodo make 3-iodo-4-hydroxy acetophenone, get 3-iodo-4-alkoxy benzene ethyl ketone, make 3-cyano group-4-alkoxy benzene ethyl ketone with cupric cyanide generation cyanogenation again, make 4-(3-cyano group 4-alkoxyl group) phenyl-2-hydroxyl-4-oxo-2-butylene acetoacetic ester with the oxalic acid diethyl ester condensation then, then get 5-(3-cyano group-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid ethyl ester with the oxammonium hydrochloride cyclization with the halohydrocarbon hydrocarbonylation, after sodium hydroxide hydrolysis, six steps made 5-(3-cyano group-4-alkoxyl group) phenyl-3-isoxazole carboxylic acid altogether.

5, a kind of medicinal compositions, it comprises claim 1 or 2 formula of I compounds or its pharmacy acceptable salt or solvate and acceptable accessories, diluent or carrier.

6, a kind of preparation method of medicinal compositions as claimed in claim 5, it is characterized in that: compound of Formula I or its pharmacy acceptable salt or solvate and acceptable accessories, diluent or carrier are mixed, the active compound that wherein contains 5-20% weight, surplus are pharmaceutically useful carrier, excipient, thinner, solvent.

7, compound of Formula I or its pharmacy acceptable salt or the solvate purposes in preparation treatment hyperuricemia and goat medicine.