An electrochemical method for preparing N-arylsulfimine compounds

Abstract

An electrochemical method for preparing N-arylsulfonylimine compound, comprising the following steps: in air atmosphere, a sulfoximine compound and an alpha-keto acid are added into a reactor in a molar ratio of 1:2, an electrolyte tetrabutylammonium tetrafluoroborate, a catalyst nickel bromide are added, and then an acetone solution is added; the mixture is stirred by a magnetic stirring device, and is dissolved; two electrodes are inserted, a graphite electrode is used as a positive electrode, and a platinum sheet electrode is used as a negative electrode; 6mA of current is passed, and the current passing time is 3h; after the reaction is completed, the solvent is removed by vacuum evaporation to obtain a crude product, and the N-arylsulfonylimine compound is obtained by column chromatography purification. Compared with a traditional synthesis method, the method has the advantages that the reaction condition is mild, can be successfully carried out at room temperature, operation is simple, all operations can be carried out in an open system, an electric current is used as an oxidation method, pollution of a chemical oxidant is avoided, raw materials are easy to obtain, functional group compatibility is good, and the scope of application of a substrate is wide.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to an electrochemical method for preparing an N-arylsulfonylimine compound. BACKGROUND

[0002] Carboxylic acids are important compounds in synthetic chemistry, pharmaceuticals, and industrial applications. Due to their accessibility, low toxicity, high stability, ease of storage and handling, carboxylic acids are also considered as starting materials in many organic transformations. In the past decade, transition-metal-catalyzed decarboxylative coupling reactions have emerged as an attractive method for the formation of carbon-carbon (C-C) and carbon-heteroatom (C-X) bonds. Many research groups have made significant contributions to this rapidly growing field.

[0003] Sulfoximine compounds are an important structural motif with strong biological and pharmaceutical activity. They have received increasing attention in the fields of chemical synthesis, medicinal chemistry, materials science, and agriculture. Some studies have shown that sulfoximine structures have high chemical stability and potential applications in medicinal chemistry. Therefore, the exploration of sulfoximines, especially the development of new and efficient synthetic methods for their derivatization, will help better understand and further improve their applications in organic, medicinal chemistry, and other related fields. SUMMARY

[0004] In view of the above problems, the application provides an electrochemical method for preparing an N-arylsulfonylimine compound, which has the advantages of mild reaction conditions, smooth operation at room temperature, simple operation, all operations can be carried out in an open system, use of electric current as an oxidation method to avoid the use of chemical oxidants, easy availability of raw materials, high reaction yield, good functional group compatibility, and wide application range of substrates.

[0005] To achieve the above object, the application provides the following technical scheme: an electrochemical method for preparing an N-arylsulfonylimine compound, which comprises the following steps:

[0006] In an air atmosphere, the sulfoximine compound and the alpha-keto acid are added to a reactor in a molar ratio of 1:2, an electrolyte tetrabutylammonium tetrafluoroborate is added, a catalyst nickel bromide is added, and then a solution of acetone is added; the mixture is stirred by a magnetic stirring device to dissolve it, two electrodes are inserted, a graphite electrode is used as the positive electrode, and a platinum sheet electrode is used as the negative electrode, 6mA of electricity is passed, the electricity passing time is 3h, after the reaction is completed, the solvent is removed by reduced pressure distillation to obtain a crude product, and the amide compound is obtained by column chromatography purification.

[0007] In the step, the reactor is a diaphragmless electrolytic cell, and the N-arylsulfonylimine compound is prepared by an electrochemical reaction, and the preparation method has the following reaction formula:

[0008]

[0009] R 1 = phenyl, each substituted phenyl; R 2 = phenyl, each substituted phenyl, each substituted aromatic heterocyclic compound; the catalyst is nickel bromide. The electrolyte is tetrabutylammonium tetrafluoroborate. The solvent is acetone.

[0010] Preferably, the anode electrode piece is a carbon rod electrode, and the cathode electrode piece is a platinum piece electrode.

[0011] Preferably, the catalyst is nickel bromide.

[0012] Preferably, the electrolyte is tetrabutylammonium tetrafluoroborate, and the concentration thereof is 0.05 mol / L.

[0013] Preferably, in the step, the reaction is carried out under open conditions and at room temperature, and a direct current stabilized power supply of 30 V / 3 A is used as the power supply, and the current is 6 mA.

[0014] Preferably, the solvent is an acetone solvent.

[0015] Preferably, in the step, the eluent used for column chromatography purification is a mixed solvent of petroleum ether and ethyl acetate, and the volume ratio of the petroleum ether: ethyl acetate is 2:1.

[0016] The present application has the following beneficial effects:

[0017] 1. The present application uses cheap and readily available sulfoximine and α-keto acid as raw materials, sulfoximine is prepared by corresponding sulfide, and α-keto acid can be prepared from corresponding phenylethanone.

[0018] 2. The present application can be operated under air conditions, is not sensitive to water and oxygen, has relatively mild reaction conditions, and is simple to operate.

[0019] 3. The present application uses current as an oxidant, which is low in cost and avoids pollution of traditional equivalent chemical oxidants.

[0020] 4. The present application can obtain the target product in one step, has high yield, good functional group compatibility, simple post-treatment, and good application potential. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The hydrogen spectrum of the product obtained in Example 1 of the present application is shown in the figure;

[0022] Figure 2 The carbon spectrum of the product obtained in Example 1 of the present application is shown in the figure;

[0023] Figure 3The hydrogen spectrum of the product obtained in Example 2 of the present application;

[0024] Figure 4 The carbon spectrum of the product obtained in Example 2 of the present application;

[0025] Figure 5 The hydrogen spectrum of the product obtained in Example 3 of the present application;

[0026] Figure 6 The carbon spectrum of the product obtained in Example 3 of the present application;

[0027] Figure 7 The hydrogen spectrum of the product obtained in Example 4 of the present application;

[0028] Figure 8 The carbon spectrum of the product obtained in Example 4 of the present application;

[0029] Figure 9 The hydrogen spectrum of the product obtained in Example 5 of the present application;

[0030] Figure 10 The carbon spectrum of the product obtained in Example 5 of the present application; DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings, so that the persons skilled in the art can better understand the advantages and features of the present application, and the protection scope of the present application can be defined more clearly. The embodiments described in the present application are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the persons skilled in the art without creative labor shall fall within the protection scope of the present application.

[0032] Example 1:

[0033] A carbon rod electrode (electrode size: diameter Φ 6 mm) was assembled as an anode and a platinum sheet (size: 10 mm x 10 mm x 0.1 mm) was assembled as a cathode in a 10 mL non-membrane electrolytic cell, then p-methylsulfoximine (33.8 mg, 0.20 mmol), benzoylformic acid (60.0 mg, 0.4 mmol) and acetone 5 mL were added, and the reaction was stirred at room temperature under a constant current of 6 mA for 3 hours. After the reaction was completed, the solvent was removed by evaporation under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 37.7 mg of the target product, with a yield of 69%. The structural formula of the obtained product is as follows:

[0034]

[0035] The structural characterization data of the obtained product are as follows:

[0036] 1H NMR (500 MHz, Chloroform-d) δ 8.23 - 8.17 (m, 2H), 7.96 (d, J = 8.6 Hz, 2H), 7.56 - 7.48 (m, 1H), 7.43 (t, J = 7.9 Hz, 4H), 3.48 (s, 3H), 2.49 (s, 3H). 13 C NMR (125 MHz, Chloroform-d) δ 174.3, 144.9, 136.0, 135.7, 132.1, 130.3, 129.4, 128.0, 127.2, 44.5, 21.6.

[0037] Example 2:

[0038] A carbon rod electrode (electrode size: diameter Φ 6 mm) was assembled as an anode and a platinum plate (size: 10 mm x 10 mm x 0.1 mm) was assembled as a cathode in a 10 mL cell without a separator, and then p-chlorosulfoximine (37.8 mg, 0.20 mmol), benzoylformic acid (60.0 mg, 0.4 mmol), and acetone 5 mL were added, and the reaction was stirred at room temperature for 3 hours at a constant current of 6 mA. After the reaction was completed, the solvent was removed by evaporation under reduced pressure to obtain a crude product, and column chromatography was performed to purify the crude product to obtain 29.9 mg of the target product at a yield of 51%. The structural formula of the obtained product is as follows:

[0039]

[0040] The structural characterization data of the obtained product are as follows:

[0041] 1 H NMR (500 MHz, Chloroform-d) δ 8.23 - 8.17 (m, 2H), 7.96 (d, J = 8.6 Hz, 2H), 7.56 - 7.48 (m, 1H), 7.43 (t, J = 7.9 Hz, 4H), 3.48 (s, 3H), 2.49 (s, 3H). 13 C NMR (125 MHz, Chloroform-d) δ 174.3, 144.9, 136.0, 135.7, 132.1, 130.3, 129.4, 128.0, 127.2, 44.5, 21.6.

[0042] Example 3:

[0043] A carbon rod electrode (electrode size: diameter Φ 6 mm) was assembled as an anode, and a platinum plate (size: 10 mm x 10 mm x 0.1 mm) was assembled as a cathode in a 10 mL electrolysis cell without a separator, and then 2-thiophenesulfoxonium ylide (31.0 mg, 0.20 mmol), 4- chlorobenzoic acid (65.6 mg, 0.4 mmol), and acetone 5 mL were added, and the reaction was stirred at room temperature at a constant current of 6 mA for 3 hours. After the reaction was completed, the solvent was evaporated under reduced pressure to obtain a crude product, and column chromatography was performed to purify the crude product to obtain 33.3 mg of the target product at a yield of 61%. The structural formula of the obtained product is as follows:

[0044]

[0045] The structural characterization data of the obtained product are as follows:

[0046] 1 H NMR (500 MHz, Chloroform-d) δ 8.29 (dd, J = 3.1, 1.5 Hz, 1H), 8.23-8.12 (m, 2H), 7.53 (pt, J = 3.5, 2.2, 1.6 Hz, 3H), 7.44 (t, J = 7.6 Hz, 2H), 3.56 (s, 3H). 13 CNMR (125 MHz, Chloroform-d) δ 174.1, 138.7, 135.5, 132.4, 132.2, 129.4, 128.9, 128.1, 125.4, 44.6.

[0047] Example 4:

[0048] A carbon rod electrode (electrode size: diameter Φ 6 mm) was assembled as an anode, and a stainless steel plate (size: 10 mm x 10 mm x 0.1 mm) was assembled as a cathode in a 10 mL electrolysis cell without a separator, and then 2-thiophenesulfoxonium ylide (31.0 mg, 0.20 mmol), 4- chlorobenzoic acid (65.6 mg, 0.4 mmol), and acetone 5 mL were added, and the reaction was stirred at room temperature at a constant current of 6 mA for 3 hours. After the reaction was completed, the solvent was evaporated under reduced pressure to obtain a crude product, and column chromatography was performed to purify the crude product to obtain 33.3 mg of the target product at a yield of 61%. The structural formula of the obtained product is as follows:

[0049]

[0050] The structural characterization data of the obtained product are as follows:

[0051] 1H NMR (500 MHz, Chloroform-d) δ 8.08 (d, J = 7.7 Hz, 4H), 7.71 (t, J = 7.4 Hz, 1H), 7.64 (t, J = 7.8 Hz, 2H), 7.24 (d, J = 7.9 Hz, 2H), 3.49 (s, 3H), 2.43 (s, 3H). 13 C NMR (125 MHz, Chloroform-d) δ 174.3, 142.7, 139.2, 133.8, 132.9, 129.7, 129.5, 128.8, 127.2, 44.4, 21.6.

[0052] Example 5:

[0053] A carbon rod electrode (electrode size: diameter Φ 6 mm) was assembled as an anode and a platinum plate (size: 10 mm x 10 mm x 0.1 mm) as a cathode in a 10 mL cell without a separator, and then sulfoximine (31.0 mg, 0.20 mmol), p-chlorobenzoylformic acid (73.6 mg, 0.4 mmol), and acetone 5 mL were added, and the reaction was stirred at room temperature for 3 hours at a constant current of 6 mA. After the reaction was completed, the solvent was evaporated under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain 32.3 mg of the target product at a yield of 55%. The structural formula of the obtained product is as follows:

[0054]

[0055] The structural characterization data of the obtained product are as follows:

[0056] 1 H NMR (500 MHz, Chloroform-d) δ 8.12 (d, J = 8.5 Hz, 2H), 8.07 (dd, J = 7.6, 1.8 Hz, 2H), 7.73 (dd, J = 8.4, 6.4 Hz, 1H), 7.65 (t, J = 7.7 Hz, 2H), 7.40 (d, J = 8.5 Hz, 2H), 3.49 (s, 3H). 13 C NMR (125 MHz, Chloroform-d) δ 173.2, 138.9, 138.5, 134.1, 133.9, 130.9, 129.8, 128.3, 127.2, 44.4.

Claims

1. An electrochemical method for preparing an N-arylsulfonylimine compound, characterized by: The preparation method comprises the following steps: in an air atmosphere, a sulfoximine compound and an alpha-keto acid are added into a reactor in a molar ratio of 1:2, an electrolyte tetrabutylammonium tetrafluoroborate and a catalyst nickel bromide are added, and then an acetone solution is added; the mixture is stirred by a magnetic stirring device to dissolve the mixture, two electrodes are inserted, a carbon rod electrode is used as an anode electrode, and a platinum electrode is used as a cathode electrode; the reaction is carried out in an open condition and at room temperature; a direct current stabilized power supply with a voltage of 30 V and a current of 3 A is used as a power supply, and a current of 6 mA is used; the current is passed for 3 h; after the reaction is completed, the solvent is removed by evaporation under reduced pressure to obtain a crude product; and the crude product is purified by column chromatography to obtain an N-arylsulfonylimine compound. In the step, the reactor is a diaphragmless electrolytic cell, and the N-arylsulfonylimine compound is prepared by an electrochemical reaction. The N-arylsulfonimidamide compounds are: ; The catalyst is nickel bromide. The electrolyte is tetrabutylammonium tetrafluoroborate. The solvent is acetone.

2. The electrochemical method for preparing an N-arylsulfonylimine compound according to claim 1, characterized by: The electrolyte is tetrabutylammonium tetrafluoroborate, and the concentration of the electrolyte is 0.05 mol / L.

3. The electrochemical method for preparing an N-arylsulfonylimine compound according to claim 1, characterized by: In the step, a mixed solvent of petroleum ether and ethyl acetate is used as an eluent for column chromatography, and the volume ratio of the petroleum ether to the ethyl acetate is 2:1.

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