A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative

Abstract

The present invention discloses a method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative. The synthesis method of this strategy is as follows: in a glass reaction vessel, a sulfoximine compound, cyclohexanone oxime, an electrolyte, and a solvent are added, and the mixture is stirred at room temperature and connected to an external DC power supply for electrolysis at a constant current of 6 mA to carry out the reaction. The crude reaction product can be obtained as a sulfoxide compound after separation and purification. The present invention has developed a method for obtaining sulfoxide compounds by electrolyzing sulfoximine compounds under electrochemistry. A series of functionalized sulfoxide derivatives can be constructed through simple electrolysis operations, which has high step economy and operational convenience. In addition, the main advantages of the reaction are that the substrates are simple and easily available, the selectivity is single, the functional group tolerance is good, and the yield is relatively high.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthetic chemistry, and particularly relates to a method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative. Background Art

[0002] Sulfoxide compounds are an important class of organic compounds, which widely exist in natural products, bioactive molecules and functional materials. Therefore, the efficient and simple preparation methods of sulfoxide compounds have always been the research hotspots and difficulties in the field of organic chemistry. With the vigorous development of the field of electrochemical organic synthesis, in recent years, the research strategy of using electrolysis technology to synthesize various types of organic compounds has provided an efficient synthesis method for the preparation of sulfoxide compounds. Compared with other methods, it has higher step economy and regioselectivity. In 2021, the Waldvogel research group reported a highly efficient oxidative hydrogen evolution reaction for the construction of imines and sulfoxide compounds from methyl phenyl sulfide and cyanamide compounds in an electrolytic cell (Martin Klein, Prof. Dr. Siegfried R. Waldvogel, Angew. Chem. Int. Ed. 2021, 60, 23197 - 23201.); in the same year, the Duan research group reported a reaction for the construction of sulfoxide compounds from sulfide compounds using a graphite sheet loaded with a special material CoFe-LDH as a modified electrode in an electrolytic cell, which has the advantages of specific selectivity and high yield (L Ma, H Zhou, M Xu, P.-P Hao, X.-P Kong, H.-H Duan, Chem. Sci, 2021, 12, 938–945). In addition, there are also examples of using different substrates in an electrolytic cell to construct sulfoxide compounds, such as alkenes, dimethyl sulfoxide, haloalkanes, etc. (Y. Yu, Y.-M. Jiang, X.-B. Zhu, Y.-Y. Lin, Y.-F. Yuan, K.-Y. Ye, Org. Chem. Front, 2022, 9, 5586–5591; K. Du, J. Huang, Green Chem, 2018, 20, 1405–1411; Y. Yu, S. Wu, X. Zhu, Y. Yuan, Z. Li, K. Ye, J. Org. Chem. 2022, 87, 10, 6942–6950.). At the same time, the sulfur-nitrogen double bond in sulfoximine compounds is a good directing group. For example, in combination with transition metal catalysis, the functionalization of inert C-H bonds on the aromatic ring can be achieved. For example, in 2017, the research group of Professor Bolm used the sulfur-nitrogen double bond in sulfoximine as a directing group to achieve the rhodium-catalyzed halogenation reaction at the ortho position of the aromatic ring (Org. Lett. 2017, 19, 726 - 729); in 2015, the Jeganmohan research group reported the rhodium-catalyzed arylation reaction at the ortho position of sulfoximine derivatives (Chem. Commun., 2015, 51, 12992 - 12995). However, the removal of the sulfoximine directing group is very difficult and there are very few relevant reports. Therefore, the development of a new method for removing the S=N directing group of sulfoximine under electrochemical conditions is a very valuable research work. Summary of the Invention

[0003] The object of the present invention is to provide a new method for synthesizing sulfoxide derivatives using sulfoximine as a reaction substrate under electrochemical conditions in view of the disadvantages and deficiencies of the prior art.

[0004] The idea of the present invention: Using sulfoximine compounds as raw materials, cis- or trans-cyclohexanone oxime or N-hydroxyphthalimide as anodic sacrificial agents, using graphite material as the anode, and stainless steel sheet, platinum sheet or nickel sheet etc. as the cathode to construct sulfoxide derivatives in one step. This method uses sulfoximine compounds as reaction raw materials, has good step economy, the required raw materials for this reaction are simple and easy to obtain, has a single selectivity, is easy to operate and has good functional group tolerance, and has potential application value.

[0005] The object of the present invention is achieved by the following technical solutions.

[0006] A method for synthesizing sulfoxide derivatives, comprising the following preparation process:

[0007] Add sulfoximine compounds, anodic sacrificial agents, electrode materials, and solvents into a reaction vessel, without a protective gas, stir at room temperature and connect an external DC power supply, and electrolyze with a constant current of 6 mA to carry out the reaction. The crude product can be obtained as a sulfoxide compound after separation and purification;

[0008] Furthermore, the preparation equation of the sulfoxide derivative is as follows:

[0009]

[0010] In the formula, R is selected from one of phenyl, 4-methylphenyl, 4-methoxyphenyl, 4-chlorophenyl, 4-bromophenyl, 3,5-dichlorophenyl and benzyl; R 1 is one of methyl, ethyl, cyclopropyl, benzyl, allyl, phenyl, 4-nitrophenyl and 4-bromophenyl;

[0011] Furthermore, the anodic sacrificial agent is cyclohexanone oxime;

[0012] Furthermore, the molar ratio of the anodic sacrificial agent to the sulfoximine compound in the feed is 1:1;

[0013] Furthermore, the electrolyte is selected from one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium thiocyanate and tetrabutylammonium perchlorate, and preferably tetrabutylammonium perchlorate;

[0014] Furthermore, the molar ratio of the electrolyte to the sulfoximine compound in the feed is 1:1.

[0015] The solvent is one or more of acetonitrile, acetone, and dimethyl sulfoxide, and preferably a mixed solvent of acetonitrile and acetone;

[0016] Furthermore, the solvent is a mixed solvent of acetonitrile and acetone, and the volume ratio thereof is 3:1;

[0017] Furthermore, the anode electrode material is one of a graphite rod and reticulated vitreous carbon, preferably a graphite rod;

[0018] Furthermore, the cathode electrode material is one of a stainless steel sheet, a platinum sheet, a nickel sheet, and a graphite rod, preferably a stainless steel sheet;

[0019] Furthermore, the stirring temperature of the reaction is 25 °C;

[0020] Furthermore, the stirring time of the reaction is 4.5 - 6 hours, preferably 4.5 hours.

[0021] Furthermore, the separation method of the crude product is column chromatography, using ethyl acetate and petroleum ether as eluents, and the volume ratio of ethyl acetate to petroleum ether is 1:1 - 1:3, preferably a mixed solvent with a volume ratio (ethyl acetate:petroleum ether) of 1:2.

[0022] The principle of the present invention is as follows: under an external DC power supply, the anode sacrificial agent loses electrons near the electrode to form free radicals, and then as a hydrogen atom transfer reagent, it converts sulfoximine into an N radical centered on nitrogen. Subsequently, the nitrogen radical couples to obtain an intermediate, and under the action of an external current, an intramolecular S=N double bond of the self-coupling intermediate spontaneously undergoes electron transfer, the S=N double bond breaks to generate nitrogen gas, and the target product is obtained.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The present invention realizes the denitrogenation reaction of sulfoximine under an electrolytic cell, and constructs a series of sulfoxide derivatives. Among them, the anode sacrificial agent cyclohexanone oxime is a commercially available raw material, which is cheap and easily available. In addition, good substrate universality and simple operation are the main characteristics of the reaction;

[0025] (2) The method for preparing sulfoxide derivatives in the present invention can be completed by a one-step reaction, and the reaction does not need to be carried out in a three-necked flask with an ion exchange membrane, which has high step economy, and thus is expected to be applied to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 、 Figure 2 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 1;

[0027] Figure 3 、 Figure 4 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 2;

[0028] Figure 5 、Figure 6 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 3;

[0029] Figure 7 、 Figure 8 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 4;

[0030] Figure 9 、 Figure 10 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 5;

[0031] Figure 11 、 Figure 12 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 6;

[0032] Figure 13 、 Figure 14 are the hydrogen spectrum and carbon spectrum of the target product obtained in Example 7. Detailed implementation manners

[0033] The present invention will be further described below through specific examples, but the protection scope and implementation manners of the present invention are not limited thereto.

[0034] Example 1

[0035] 0.2 mmol of methylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was carried out with constant stirring at a current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure methylphenyl sulfone was obtained with a yield of 76%.

[0036] The hydrogen spectrum and carbon spectrum of the obtained target product are as shown in Figure 1 and Figure 2 as follows, and the structure characterization data is as follows:

[0037] 1 H NMR(500MHz,CDCl3)δ7.60(d,J=7.8Hz,2H),7.54–7.39(m,3H),2.67(s,3H);

[0038] 13 C NMR(125MHz,CDCl3)δ145.5,131.0,129.3,123.4,43.8;

[0039] Based on the above characterization data, the structure of the target compound is as follows:

[0040]

[0041] Example 2

[0042] 0.2 mmol of 4-methylphenyl-S-methylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred under constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent for column chromatography used was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure 4-methylphenyl-S-methylsulfoxide was obtained with a yield of 68%.

[0043] The 1H NMR and 13C NMR spectra of the obtained target product are as Figure 3 and Figure 4 shown, and the structure characterization data are as follows:

[0044] 1 H NMR(500MHz,CDCl3)δ7.52(d,J=8.0Hz,2H),7.31(d,J=7.8Hz,2H),2.69(s,3H),2.40(s,3H);

[0045] 13 C NMR(125MHz,CDCl3)δ142.5,141.7,130.1,123.7,44.0,21.5;

[0046] Based on the above characterization data, the structure of the target compound is as follows:

[0047]

[0048] Example 3

[0049] In a three-necked flask, 0.2 mmol of 4-methoxyphenyl-S-methylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were added in sequence. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried with anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure 4-methoxyphenyl-S-methyl sulfoxide was obtained with a yield of 71%.

[0050] The 1H NMR and 13C NMR spectra of the obtained target product are as shown in Figure 5 and Figure 6 shown below, and the structure characterization data are as follows:

[0051] 1 H NMR(500MHz,CDCl3)δ7.53(d,J=8.7Hz,2H),6.96(d,J=8.7Hz,2H),3.78(s,3H),2.64(s,3H);

[0052] 13 C NMR(125MHz,CDCl3)δ161.9,136.4,125.4,114.8,55.5,43.9;

[0053] Based on the above characterization data, the structure of the target compound is inferred as follows:

[0054]

[0055] Example 4

[0056] In a three-necked flask, 0.2 mmol of 4-chlorophenyl-S-methylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were added in sequence. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried with anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure 4-chlorophenyl-S-methyl sulfoxide was obtained with a yield of 82%.

[0057] The 1H NMR and 13C NMR spectra of the obtained target product are as shown in Figure 7 and Figure 8As shown, the structure characterization data are as follows:

[0058] 1 H NMR (500 MHz, CDCl3) δ 7.58 (d, J = 8.4 Hz, 2H), 7.50 (d, J = 8.4 Hz, 2H), 2.71 (s, 3H);

[0059] 13 C NMR (125 MHz, CDCl3) δ 144.3, 137.4, 129.8, 125.1, 44.2;

[0060] Based on the above characterization data, the structure of the target compound is as follows:

[0061]

[0062] Example 5

[0063] 0.2 mmol of 4-bromophenyl-S-methylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent for column chromatography used was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure 4-chlorophenyl-S-methylsulfoxide was obtained with a yield of 73%.

[0064] The 1H NMR and 13C NMR spectra of the obtained target product are as Figure 9 and Figure 10 shown, and the structure characterization data are as follows:

[0065] 1 H NMR (500 MHz, CDCl3) δ 7.63 (d, J = 8.3 Hz, 2H), 7.49 (d, J = 8.3 Hz, 2H), 2.68 (s, 3H);

[0066] 13 C NMR (125 MHz, CDCl3) δ 144.9, 132.6, 125.5, 125.2, 44.0;

[0067] Based on the above characterization data, the structure of the target compound is as follows:

[0068]

[0069] Example 6

[0070] 0.2 mmol of 3,5-dichlorophenyl-S-methylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred under constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure 4-chlorophenyl-S-methylsulfoxide was obtained with a yield of 73%.

[0071] The 1H NMR and 13C NMR spectra of the obtained target product are as Figure 11 and Figure 12 shown below, and the structure characterization data are as follows:

[0072] 1 H NMR (500 MHz, CDCl3) δ 7.82–7.32 (m, 3H), 2.74 (s, 3H);

[0073] 13 C NMR (125 MHz, CDCl3) δ 149.5, 136.4, 131.2, 122.1, 44.1;

[0074] Based on the above characterization data, the structure of the target compound is inferred as follows:

[0075]

[0076] Example 7

[0077] 0.2 mmol of ethylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred under constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure ethylphenylsulfoxide was obtained with a yield of 74%.

[0078] The 1H NMR and 13C NMR spectra of the obtained target product are as Figure 13 and Figure 14 shown below, and the structure characterization data are as follows:

[0079] 1 1H NMR (500 MHz, CDCl3) δ 7.51 (dd, J = 47.9, 7.1 Hz, 5H), 2.79 (dd, J = 62.2, 6.7 Hz, 2H), 1.14 (t, J = 7.4 Hz, 3H);

[0080] 13 13C NMR (125 MHz, CDCl3) δ 143.2, 131.0, 129.1, 124.2, 50.2, 5.9.

[0081] Based on the above characterization data, the structure of the target compound is as follows:

[0082]

[0083] Example 8

[0084] 0.2 mmol of cyclopropylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure cyclopropylphenyl sulfoxide was obtained with a yield of 69%.

[0085] The structure characterization data of the obtained target product are as follows:

[0086] 1 1H NMR (500 MHz, CDCl3) δ 7.70–7.61 (m, 2H), 7.50 (d, J = 7.1 Hz, 3H), 2.31–2.20 (m, 1H), 1.24–1.19 (m, 1H), 1.05–0.99 (m, 1H), 0.99–0.90 (m, 2H);

[0087] 13 13C NMR (125 MHz, CDCl3) δ 144.8, 130.9, 129.1, 124.0, 33.8, 3.4, 2.8;

[0088] Based on the above characterization data, the structure of the target compound is as follows:

[0089]

[0090] Example 9

[0091] 0.2 mmol of benzylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure benzylphenylsulfoxide was obtained with a yield of 78%.

[0092] The structural characterization data of the obtained target product are as follows:

[0093] 1 H NMR(500MHz,CDCl3)δ7.45(dt,J=15.3,7.0Hz,3H),7.39(d,J=7.0Hz,2H),7.30–7.24(m,3H),6.99(d,J=7.2Hz,2H),4.11(d,J=12.6Hz,1H),4.01(d,J=12.6Hz,1H);

[0094] 13 C NMR(125MHz,CDCl3)δ142.7,131.2,130.3,129.1,128.8,128.4,128.2,124.4,63.5;

[0095] Based on the above characterization data, the structure of the target compound is inferred as follows:

[0096]

[0097] Example 10

[0098] 0.2 mmol of S - propenylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure S - propenylphenylsulfoxide was obtained with a yield of 75%.

[0099] The structural characterization data of the obtained target product are as follows:

[0100] 1 H NMR(500MHz,CDCl3)δ7.60–7.51(m,2H),7.46(d,J=7.1Hz,3H),5.59(td,J=17.4,7.5Hz,1H),5.27(d,J=10.2Hz,1H),5.14(d,J=17.0Hz,1H),3.49(ddd,J=35.8,12.8,7.6Hz,2H);

[0101] 13 C NMR(125MHz,CDCl3)δ142.8,131.1,129.0,125.2,124.3,123.9,60.8;

[0102] Based on the above characterization data, the structure of the target compound is as follows:

[0103]

[0104] Example 11

[0105] 0.2 mmol of S-phenylbenzenesulfinimine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). The pure S-phenylbenzenesulfoxide was obtained with a yield of 63%.

[0106] The structural characterization data of the obtained target product are as follows:

[0107] 1 H NMR(500MHz,CDCl3)δ7.64(d,J=6.9Hz,4H),7.44(d,J=6.9Hz,6H);

[0108] 13 C NMR(125MHz,CDCl3)δ145.7,131.2,129.4,124.9;

[0109] Based on the above characterization data, the structure of the target compound is as follows:

[0110]

[0111] Example 12

[0112] 0.2 mmol of S-4-nitrophenylphenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure S-4-nitrophenylphenyl sulfoxide was obtained with a yield of 41%.

[0113] The structural characterization data of the obtained target product are as follows:

[0114] 1 H NMR(500MHz,CDCl3)δ8.29(d,J=8.8Hz,2H),7.82(d,J=8.8Hz,2H),7.71–7.62(m,2H),7.54–7.41(m,3H);

[0115] 13 C NMR(125MHz,CDCl3)δ153.0,149.3,144.5,132.1,129.9,125.4,125.0,124.5;

[0116] Based on the above characterization data, the structure of the target compound is inferred as follows:

[0117]

[0118] Example 13

[0119] 0.2 mmol of benzylbenzylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred with a constant current of 6 mA at room temperature for 4.5 h. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure benzylbenzyl sulfoxide was obtained with a yield of 60%.

[0120] The structural characterization data of the obtained target product are as follows:

[0121] 1 H NMR(500MHz,CDCl3)δ8.17–6.91(m,10H),3.90(q,J=13.0Hz,4H);

[0122] 13 C NMR(125MHz,CDCl3)δ130.2(d,J=1.8Hz),129.0,128.4,57.3;

[0123] Based on the above characterization data, the structure of the target compound is as follows:

[0124]

[0125] Example 14

[0126] 0.2 mmol of S-4-bromo-phenyl-4-bromophenylsulfoximine, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (volume ratio 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred under a constant current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure S-4-bromo-phenyl-4-bromophenylsulfoxide was obtained with a yield of 52%.

[0127] The structural characterization data of the obtained target product are as follows:

[0128] 1 H NMR(500MHz,CDCl3)δ7.57(d,J=8.4Hz,4H),7.47(d,J=8.5Hz,4H);

[0129] 13 C NMR(125MHz,CDCl3)δ144.4,132.8,126.2,126.0.

[0130] Based on the above characterization data, the structure of the target compound is as follows:

[0131]

[0132] Example 15

[0133] 0.2 mmol of diphenylthiophenesulfonimide, 0.2 mmol of cyclohexanone oxime, and 0.2 mmol of tetrabutylammonium perchlorate were successively added to a three-necked flask. Subsequently, 4 mL of a mixed solvent of anhydrous acetonitrile and acetone (with a volume ratio of 3:1) was added. A graphite rod was used as the anode and a stainless steel sheet was used as the cathode. The reaction was stirred under an electric current of 6 mA at room temperature for 4.5 hours. The reaction was stopped, filtered, and the filtrate was extracted with ethyl acetate three times. The organic phases were combined and dried with anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure by rotary evaporation to obtain a crude product. Finally, it was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether and ethyl acetate (petroleum ether:ethyl acetate = 1:1). Pure diphenylthiophenesulfone was obtained with a yield of 49%.

[0134] The structural characterization data of the obtained target product are as follows:

[0135] 1 H NMR (500 MHz, CDCl3) δ 7.99 (d, J = 7.6 Hz, 2H), 7.81 (d, J = 7.6 Hz, 2H), 7.60 (t, J = 7.4 Hz, 2H), 7.50 (t, J = 7.4 Hz, 2H);

[0136] 13 C NMR (125 MHz, CDCl3) δ 137.3, 132.7, 129.7, 127.7, 122.1;

[0137] Based on the above characterization data, the structure of the target compound is inferred as follows:

[0138]

[0139] The above embodiments are partial embodiments of the present invention. The specific embodiments of the present invention are not affected by the above embodiments. Any other structural modifications and condition simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative, characterized in that, It comprises the following steps: In a glass reaction vessel, add a sulfoximine compound, an anodic sacrificial agent, an electrolyte, and a solvent. Stir at room temperature and connect an external DC power supply. Electrolyze at a constant current of 6 mA to carry out the reaction. After separation and purification of the crude product, a sulfoxide compound can be obtained; The above reaction is shown by the following formula: , where R is selected from one of phenyl, 4-methylphenyl, 4-methoxyphenyl, 4-chlorophenyl, 4-bromophenyl, 3,5-dichlorophenyl and benzyl; R 1 is selected from one of methyl, ethyl, cyclopropyl, benzyl, allyl, phenyl, 4-nitrophenyl and 4-bromophenyl; the anodic sacrificial agent is cyclohexanone oxime; the electrolyte is selected from one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium thiocyanate and tetrabutylammonium perchlorate; the solvent is one or more of acetonitrile, acetone and dimethyl sulfoxide; the anodic electrode material is one of a graphite rod and reticulated vitreous carbon; the cathodic electrode material is one of a stainless steel sheet, a platinum sheet, a nickel sheet and a graphite rod.

2. The method for preparing sulfoxide derivatives by electrochemically promoting the removal of a directing group from sulfoximine according to claim 1, wherein The molar ratio of the anodic sacrificial agent to the sulfoximine compound in the feed is 1:

1.

3. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative according to claim 1, characterized in that, The molar ratio of the electrolyte to the sulfoximine compound in the feed is 1:

1.

4. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative according to claim 1, characterized in that, The electrolysis electrode uses a graphite rod as the anode and a stainless steel sheet as the cathode.

5. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative according to claim 1, characterized in that, The solvent is a mixed solvent of acetonitrile and acetone, and their volume ratio is 3:

1.

6. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative according to claim 1, characterized in that, The reaction time of the preparation method is 4.5 - 6 hours.

7. A method for electrochemically promoting the removal of a directing group from a sulfoximine to prepare a sulfoxide derivative according to claim 1, characterized in that, The separation method of the crude product is column chromatography, using ethyl acetate and petroleum ether as eluents.

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