An electrochemical synthesis method for α,β-diarylamide compounds

Abstract

This invention relates to an electrochemical synthesis method for α,β-diarylamide compounds, comprising: mixing an aryl diazonium salt, an aryl olefin, an electrolyte, an alkyl nitrile, and water to obtain a reaction system; and subjecting the reaction system to an electrocatalytic reaction to synthesize α,β-diarylamide compounds. This invention utilizes an electrochemical synthesis method to obtain α,β-diarylamide compounds, eliminating the need for expensive ruthenium catalysts. The synthesis strategy is economical and efficient, meeting the requirements of green chemical engineering development. Furthermore, gram-scale experiments have fully verified the industrial applicability of this invention.

Description

Technical Field

[0001] This invention relates to the field of electrochemical synthesis technology of aryl amide compounds, and specifically to an electrochemical synthesis method for α,β-diaryl amide compounds. Background Technology

[0002] α,β-Diarylamides are important structural components of bioactive natural products, pharmaceuticals, pesticides, and other functional molecules, and their synthesis has attracted increasing attention from researchers over the past few decades. One of the most efficient and convenient methods is the one-step conversion of olefins to α,β-diarylamides via the aryl-amino bifunctionalization reaction. This method was first developed by Durga Prasad Hari et al. in 2014, who pioneered the use of a transition metal ruthenium (Ru) catalyst under photoluminescence to convert olefins to α,β-diarylamides. Figure 1 Although this method successfully converts olefins into α,β-diarylamide compounds, the high cost of ruthenium catalysts (approximately 250 yuan per gram) and the presence of transition metal residues significantly limit its application in fields such as chemical engineering and pharmaceuticals.

[0003] Therefore, there is an urgent need to develop a novel, green synthetic method to convert olefins into α,β-diarylamides to overcome these limitations. Organic electrochemical synthesis, also known as organic electrosynthesis, is called a "green synthetic tool." Compared with traditional chemistry, electrochemical synthesis has advantages such as being green and sustainable, highly efficient, and operating under mild conditions, avoiding the use of additional oxidizing or reducing agents.

[0004] Therefore, it is necessary to construct a method for preparing α,β-diarylamide compounds based on organic electrosynthesis. Summary of the Invention

[0005] The purpose of this invention is to replace the traditional expensive ruthenium catalyst with an organic electrosynthesis strategy to achieve amino-aryl bifunctionalization of olefins by aryl diazonium salts and alkyl nitriles, thereby preparing α,β-diaryl amide compounds and providing a more economical and green synthetic route for the synthesis of α,β-diaryl amide compounds.

[0006] To achieve the above objectives, the present invention provides an electrochemical synthesis method for α,β-diarylamide compounds, comprising, The reaction system is obtained by mixing aryl diazonium salt, aryl olefin, electrolyte, alkyl nitrile and water; The reaction system was subjected to electrocatalytic reaction to synthesize α,β-diarylamide compounds.

[0007] Furthermore, the molar ratio of the aryl diazonium salt, the aryl olefin, and the electrolyte is 1:3-8:0.5-1.5; The ratio of the aryl diazonium salt to alkyl nitrile and water is 0.1-0.15g:3-10mL:1-5mL.

[0008] Furthermore, the structural formula of the aryl diazonium salt is as follows: ; R1 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, trifluoromethyl, methyl, and methoxy.

[0009] Furthermore, the structural formula of the aryl olefin is as follows: ; R2 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, cyano, trifluoromethyl, methyl, and methoxy, and R3 includes at least one of hydrogen, aryl, and alkyl.

[0010] Furthermore, the alkyl nitrile has the structural formula R4CN; R4 includes at least one of methyl, ethyl, propyl, isopropyl, cyclopropyl, and butyl.

[0011] Further, the electrolyte includes n Bu4NClO4、 n At least one of Bu4NBF4 and LiClO4.

[0012] Furthermore, the electrocatalytic reaction is carried out for 3-6 hours at a current of 3-8 mA.

[0013] Furthermore, the electrocatalytic reaction uses graphite felt as the anode and platinum as the cathode.

[0014] Furthermore, the electrocatalytic reaction is carried out under a protective gas atmosphere.

[0015] Furthermore, the electrocatalytic reaction is carried out at 10-30°C.

[0016] The present invention also provides an α,β-diarylamide compound, which is obtained by the above-described electrochemical synthesis method.

[0017] Compared with the prior art, the beneficial effects of the present invention include: The electrochemical synthesis of α,β-diarylamide compounds eliminates the need for expensive ruthenium catalysts, making the synthesis strategy economical and efficient, and aligning with the requirements of green chemical engineering. Furthermore, gram-scale experiments fully validated the industrial applicability of this invention. Attached Figure Description

[0018] Figure 1 The reaction formula for the current photocatalytic synthesis of α,β-diarylamide compounds is shown; Figure 2 The reaction formula for the electrochemical synthesis of α,β-diarylamide compounds of the present invention is shown; Figure 3 The synthesis reaction formula for the diazonium salt of 4-nitrobenzenetetrafluoroborate is shown; Figure 4 The reaction formula for the electrochemical synthesis method of α,β-diarylamide compounds in Example 1 of the present invention is shown; Figure 5 The 1H NMR spectrum of the product prepared in Example 1 of this invention is shown. Figure 6 The carbon NMR spectrum of the product prepared in Example 1 of this invention is shown; Figure 7 The 1H NMR spectrum of the product prepared in Example 4 of this invention is shown. Figure 8 The carbon NMR spectrum of the product prepared in Example 4 of this invention is shown. Figure 9 The 1H NMR spectrum of the product prepared in Example 5 of this invention is shown. Figure 10 The carbon NMR spectrum of the product prepared in Example 5 of this invention is shown. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0021] The concept of this invention lies in the fact that aryl diazonium salts have low reduction potentials and are easily reduced by directly gaining electrons, thus eliminating the need for metal catalysts to efficiently generate aryl radicals and nitrogen gas. The carbon radical intermediate can be further oxidized to a carbocation. The cyano nitrogen atom in the alkyl nitrile has strong nucleophilicity and can capture the carbocation, generating the corresponding nitrile onium ion intermediate. This intermediate is readily hydrolyzed, and can be converted into the target α,β-diarylamide compound in the presence of post-reaction processing or trace amounts of water in the system. However, this process still needs to overcome some problems, such as: 1. Competition for reaction pathways: The aryl radicals generated during the reduction of aryl diazonium salts may directly gain an electron from the electrode surface and be reduced to aryl anions, which may then undergo protonation to generate byproducts; 2. Stability of intermediates: The microenvironment (such as current intensity) on the electrode surface during electrochemical reactions has a significant impact on the lifetime and reactivity of the intermediates (carbon radicals, carbocations). The key is to regulate the reaction so that it can be captured by the nucleophile without undergoing other side reactions (such as elimination or polymerization); 3. Separation and purification: Although the target product is an amide, a nitrile onion or nitrile intermediate may be formed first in the reaction pathway. It is necessary to optimize the reaction conditions (such as controlling the trace amount of water in the system) to ensure that the post-processing can efficiently and completely convert it into the target amide product.

[0022] In view of this, such as Figure 2 As shown, this invention provides an electrochemical synthesis method for α,β-diarylamide compounds, comprising, The reaction system is obtained by mixing aryl diazonium salt, aryl olefin, electrolyte, alkyl nitrile and water; The reaction system was subjected to electrocatalytic reaction to synthesize α,β-diarylamide compounds.

[0023] This invention does not strictly limit the acquisition of raw materials; they can be directly purchased products or those prepared according to [specific requirements]. Figure 3 The reaction was used to synthesize the solution. For example, when the aryl diazonium salt is selected as 4-nitrophenyltetrafluoroborate diazonium salt, the preparation method is as follows: Weigh 4.97 g (36 mmol) of 4-nitroaniline, 10 mL of deionized water, and 20 mL of fluoroboric acid (40% wt) into a 250 mL round-bottom flask. Add a stir bar and stir. After 15 min in an ice bath, weigh 2.508 g (36.36 mmol) of sodium nitrite and 10 mL of deionized water into a 25 mL constant-pressure dropping funnel. Slowly add the sodium nitrite solution dropwise to the mixed solution containing 4-nitroaniline. After the addition is complete, continue the ice bath for 60 min to obtain a mixed solution of 4-nitrophenyltetrafluoroborate diazonium salt. Then, the filter cake was collected by vacuum filtration and transferred to a round-bottom flask. It was recrystallized with acetone / ether and then filtered again. The filter cake was washed three times with ether and dried in a vacuum oven at 40°C for 6 hours to obtain pure and dry 4-nitrobenzene tetrafluoroborate diazonium salt.

[0024] In some preferred embodiments, the molar ratio of the aryl diazonium salt, the aryl olefin, and the electrolyte is 1:3-8:0.5-1.5; The ratio of the aryl diazonium salt to alkyl nitrile and water is 0.1-0.15g:3-10mL:1-5mL.

[0025] In some preferred embodiments, the structural formula of the aryl diazonium salt is: ; R1 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, trifluoromethyl, methyl, and methoxy.

[0026] In some preferred embodiments, the aryl olefin has the following structural formula: ; R2 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, cyano, trifluoromethyl, methyl, and methoxy; R3 includes hydrogen, aryl, alkyl, etc.; and R4 is at least one of methyl, ethyl, propyl, isopropyl, cyclopropyl, and butyl.

[0027] In some preferred embodiments, the alkyl nitrile has the structural formula R4CN; R4 includes at least one of methyl, ethyl, propyl, isopropyl, cyclopropyl, and butyl. In some preferred embodiments, the electrolyte includes n Bu4NClO4、 n At least one of Bu4NBF4 and LiClO4.

[0028] In some preferred embodiments, the electrocatalytic reaction is sustained for 3-6 hours at a current of 3-8 mA.

[0029] In some preferred embodiments, the electrocatalytic reaction uses graphite felt as the anode and platinum as the cathode.

[0030] In some preferred embodiments, the electrocatalytic reaction is carried out under a protective gas atmosphere. The protective gas consists of at least one of nitrogen, argon, and helium.

[0031] In some preferred embodiments, the electrocatalytic reaction is carried out at 10-30°C. The electrocatalytic reaction occurs at room temperature without heating.

[0032] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0035] Example 1 like Figure 4 As shown, an electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system, and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1). Figure 5 and Figure 6 The hydrogen NMR spectrum and carbon NMR spectrum of the target product are shown respectively.

[0036] Example 2 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 295 mg (2.5 mmol) of styrene. n Bu4NBF4 (165 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0037] Example 3 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt, 295 mg (2.5 mmol) of styrene, 53 mg (0.5 mmol) of LiClO4, and 10 mL of MeCN / H2O (v / v = 4:1, 10 mL) into a 25 mL single-necked flask equipped with a stir bar and stir to obtain the reaction system; insert a 10 × 10 mm graphite felt electrode into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0038] Example 4 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 111 mg (0.5 mmol) of 4-methoxybenzyl tetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system, and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1). Figure 7 and Figure 8 The hydrogen NMR spectrum and carbon NMR spectrum of the target product are shown respectively.

[0039] Example 5 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of 4-fluorostyrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system, and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1). Figure 9 and Figure 10 The hydrogen NMR spectrum and carbon NMR spectrum of the target product are shown respectively.

[0040] Example 6 Compared with Example 5, the difference is that 4-nitrophenyltetrafluoroborate diazonium salt is replaced with 4-trifluoromethylbenzenetetrafluoroborate diazonium salt in the same molar amount.

[0041] Example 7 Compared with Example 5, the difference is that 4-nitrophenyltetrafluoroborate diazonium salt is replaced with 4-bromophenyltetrafluoroborate diazonium salt in the same molar amount.

[0042] Example 8 Compared with Example 5, the difference is that 4-nitrophenyltetrafluoroborate diazonium salt is replaced with 4-chlorophenyltetrafluoroborate diazonium salt in the same molar amount.

[0043] Comparative Example 1 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and without current flow, the mixture was stirred continuously for 5 hours. After the reaction was completed, it was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. Column chromatography was performed on silica gel using petroleum ether and ethyl acetate as eluents (10:1). The target product was not obtained.

[0044] Comparative Example 2 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite plate electrode (10 × 10 mm) was then inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0045] Comparative Example 3 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a carbon fiber electrode (10 × 10 mm) was then inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system, and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. Column chromatography was performed on silica gel using petroleum ether and ethyl acetate as eluents (10:1) to obtain the target product. Comparative Example 4 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. nBu4NClO4 (171 mg, 0.5 mmol) and MeCN (10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0046] Comparative Example 5 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 10:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system, and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. Column chromatography was performed on silica gel using petroleum ether and ethyl acetate as eluents (10:1) to obtain the target product. Comparative Example 6 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 1:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 5 mA current was applied to the reaction system and the reaction was carried out for 5 h. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0047] Comparative Example 7 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a 2mA current was applied to the reaction system and the reaction was carried out for 8 hours. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0048] Comparative Example 8 An electrochemical synthesis method for α,β-diarylamide compounds includes the following steps: S1. Weigh out 118 mg (0.5 mmol) of 4-nitrobenzenetetrafluoroborate diazonium salt and 260 mg (2.5 mmol) of styrene. n Bu4NClO4 (171 mg, 0.5 mmol) and MeCN / H2O (v / v = 4:1, 10 mL) were added to a 25 mL single-necked flask equipped with a stir bar and stirred to obtain the reaction system; a graphite felt electrode (10 × 10 mm) was inserted into the single-necked flask. 2 As the anode, a platinum plate electrode (10×10mm) 2 ) as the cathode; S2. Under a nitrogen atmosphere and with continuous stirring, a current of 10 mA was applied to the reaction system and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was extracted with ethyl acetate and water. The composite organic layer was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by a rotary evaporator. The target product was obtained by column chromatography on silica gel using petroleum ether and ethyl acetate as eluents (10:1).

[0049] The yields of the target products in the examples and comparative examples were tested, and the results are shown in Table 1.

[0050] Table 1. Yield of the target product

[0051] The yields of the target products obtained in Examples 1, 4, and 5 were all above 80%, demonstrating that the present invention successfully synthesized α,β-diarylamide compounds via electrochemical synthesis without the use of expensive ruthenium catalysts, and with high yields. The yields of Examples 2 and 3 were significantly lower than those of Example 1. Comparative Example 1 failed to yield the target product because, without current, the cathode lacked reducing power and could not reduce the aryl diazonium salt to form an aryl radical intermediate, thus preventing the initiation of subsequent reactions. The significant decrease in yields of Examples 2 and 3 compared to Example 1 illustrates the necessity of an electrolyte for the reaction and the advantage of selecting a suitable electrolyte in improving yields. The significant decrease in yields of Comparative Examples 2 and 3 compared to Example 1 indicates that the type of anode material has a certain influence on the reaction. Comparative Examples 4-6 differed from Example 1 in the ratio of alkyl nitrile to water. In particular, the yield of the anhydrous Comparative Example 4 was only 32%, which may be because the intermediate is highly susceptible to hydrolysis. In post-reaction processing or the presence of trace amounts of water in the system, it is more easily converted into the target α,β-diarylamide. Optimizing the ratio of alkyl nitrile to water facilitates the electrocatalytic reaction. Comparative Examples 7 and 8, compared to Example 1, showed different current intensities and significantly lower yields, indicating that a moderate current is more conducive to the electrocatalytic reaction.

[0052] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An electrochemical synthesis method for α,β-diarylamide compounds, characterized in that, include, The reaction system is obtained by mixing aryl diazonium salt, aryl olefin, electrolyte, alkyl nitrile and water; The reaction system was subjected to electrocatalytic reaction to synthesize α,β-diarylamide compounds.

2. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The molar ratio of the aryl diazonium salt, aryl olefin, and electrolyte is 1:3-8:0.5-1.5; The ratio of the aryl diazonium salt to alkyl nitrile and water is 0.1-0.15g:3-10mL:1-5mL.

3. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The structural formula of the aryl diazonium salt is as follows. ； R1 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, trifluoromethyl, methyl, and methoxy.

4. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The structural formula of the aryl olefin is as follows. ； R2 includes at least one of hydrogen, fluorine, chlorine, bromine, nitro, cyano, trifluoromethyl, methyl, and methoxy, and R3 includes at least one of hydrogen, aryl, and alkyl.

5. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The structural formula of the alkyl nitrile is R4CN; R4 includes at least one of methyl, ethyl, propyl, isopropyl, cyclopropyl, and butyl.

6. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The electrolyte includes n Bu4NClO4、 n At least one of Bu4NBF4 and LiClO4.

7. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The electrocatalytic reaction was carried out for 3-6 hours at a current of 3-8 mA.

8. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The electrocatalytic reaction uses graphite felt as the anode and platinum as the cathode.

9. The electrochemical synthesis method for α,β-diarylamide compounds according to claim 1, characterized in that, The electrocatalytic reaction is carried out at 10-30°C under a protective atmosphere.

10. An α,β-diarylamide compound, characterized in that, It is obtained by the electrochemical synthesis method according to any one of claims 1-9.

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