Electrochemical method for realizing aryl boride Ipso-nitration by using ferric nitrate as nitro source

Abstract

The invention discloses an electrochemical method for realizing aryl boride Ipso-nitration by using ferric nitrate as a nitration source, which specifically comprises the following steps: mixing aryl boride as a raw material, ferric nitrate as a nitration reagent, tetrabutylammonium tetrafluoroborate as an electrolyte and acetic acid as an additive with a solvent, and reacting under the conditions that the current is 15mA and the temperature is 70 DEG C by using Pt (+) / Pt (-) as a positive electrode and a negative electrode, the aryl boride Ipso-nitration product is obtained. According to the invention, aryl boride compounds with different structures are used as raw materials, ferric nitrate is used as a nitration reagent, and nitration reaction of aryl boride Ipso is successfully realized. Clean electric energy is used as driving force, and an organic boron reagent which is relatively low in reactivity and more stable is utilized, so that the application range of a substrate and the tolerance of functional groups are remarkably improved, and the method has the advantages of simple and easily available reagent, simplicity and convenience in operation, high yield, environmental friendliness and the like.

Description

Technical Field

[0001] The present invention relates to the synthesis of organic compounds, and in particular to an electrochemical method for realizing Ipso-nitration of aryl boride using ferric nitrate as a nitro source. Background Art

[0002] Nitroaromatic compounds occupy a prominent position in organic synthetic chemistry due to their easy conversion into amides, azo compounds, amines, and heterocyclic compounds. These compounds have been widely used in fields such as pharmaceuticals, agriculture, materials science, dyes, and explosives. Traditionally, the synthesis of nitroaromatics has primarily relied on the mixed acid method (H2SO4-HNO3 system), but this method has significant limitations: the nitration of substituted aromatics often inevitably produces a mixture of isomers and exhibits poor tolerance to functional groups. Furthermore, the requirement for large amounts of highly corrosive acids makes this method unsuitable for green chemistry.

[0003] Nitroaromatic compounds are key starting materials for the production of a variety of chemical products and have attracted extensive research by chemists. The methods currently reported in the literature are as follows:

[0004] (1) Nitroaromatic compounds react under strong acid conditions. For example, aromatic boronic acid compounds react with trifluoroacetic acid and nitric acid in water to achieve Ipso-nitration (Shen, G.; Zhao, L.; Liu, W. Synthetic Communications, 2016: 00397911.). Aryl boronic acid compounds react with Cu(NO3)2 / CF3COOH in ethyl acetate to achieve Ipso-nitration (Wang. Zhu,; QG; Meng, PW; Yong, JS; Xiu, LL; Mei, Y. Zhou.; Xiu, L. Letters in organic chemistry, 2018, 15(10).). Arylboronic acids react with fuming nitric acid in 1,2-dichloroethane to achieve Ipso-nitration (Murray, JI; Elipe, MVS; Baucom, KD. The Journal of Organic Chemistry, 2021. acs. joc. 1c00886.). Aromatic or substituted aromatic hydrocarbons react with concentrated nitric acid in hexafluoroisopropanol to achieve nitration (Ma, YN; Wu, YXCN202211361893.). Aromatic hydrocarbons, HNO3, and trifluoromethanesulfonic acid react in hexafluoroisopropanol or in the absence of solvent to achieve nitration (Wu, Y.; Lu, W.; Ma, YN. JOrg. Chem. 2023, 88, 11322-11327.).

[0005] This type of reaction primarily utilizes large amounts of strong acids, but this method has significant limitations: the nitration of substituted aromatics often results in the inevitable formation of isomer mixtures and poor tolerance to functional groups. Furthermore, the requirement for large amounts of highly corrosive acids makes this method incompatible with green chemistry requirements.

[0006] (2) Aryl boronates undergo Ipso-nitration reaction under catalytic conditions. For example, aryl boronic acid compounds, sodium nitrate and catalyst copper oxide can be used to carry out Ipso-nitration reaction in ammonia water (Yang, H.; Li, Y.; Jiang, M.; Wang, J.; Fu, H. Chemistry: A European journal, 2011, 17(20).). Aryl boronic acid compounds, tetrabutylammonium nitrate and catalyst copper oxide can be used to carry out Ipso-nitration reaction in acetonitrile (Yan, G.; Zhang, L.; Yu, J. Letters inorganic chemistry, 2012(2):9.). Aryl boronic acid compounds, bismuth nitrate pentahydrate and catalyst Tert-butyl hydroperoxide can be used to carry out Ipso-nitration reaction in 1,2-dichloroethane (Yan, XH; Li. Chinese Journal of Organic Chemistry, 2017.). Ipso-nitration of aryl boronic acid compounds, zirconyl nitrate and iodine catalyst in toluene (Mahanta, A.; Gour, NK; Sarma, PJ Applied Organometallic Chemistry, 2019, 33(8).). Ipso-nitration of aryl boronic acid compounds, ferric nitrate and CoFe2O4 catalyst in toluene (Bora, J.; Dutta, M.; Chetia, T. Journal of Molecular Structure, 2025, 1319(Part 1): 139418). Ipso-nitration of aryl boronic acid compounds, sodium nitrate and graphite catalyst in aqueous medium (Dandia, A.; Sharma, R.; Saini, P. RSC Advances, 11[2025-03-26].). Arylboronic acid compounds, sodium nitrate, and ferric nitrate can achieve Ipso-nitration reaction in acetonitrile under photocatalysis (Shu, YL; Y, SL; H, YW; Zhi, YX; Zi, YX ACS Catal. 2025, 15, 3306-3313.).

[0007] Although this type of reaction successfully achieves the Ipso-nitration reaction of aromatic borides, the catalyst selectivity is poor. The existing catalysts may only be applicable to specific types of aromatic borides and have poor catalytic effects on substrates with complex structures.

[0008] (3) Ipso-nitration of aryl boronic acid compounds under electrochemical conditions. For example, aryl boronic acid compounds, bismuth nitrate, and tetrabutylammonium fluoroborate were used to achieve Ipso-nitration under potentiostatic electrochemical conditions (Huang, JM; Qi, HMCN201210216024.1). Although the method described in this patent successfully achieved Ipso-nitration of aryl boronates, the reaction time was long, and it was only applicable to specific types of aryl boronic acid compounds. In addition, it showed significant selectivity for substrates substituted with electron-withdrawing groups. Summary of the Invention

[0009] In view of the above-mentioned problems, the present invention provides an electrochemical reaction method for the Ipso-nitration of aryl boride using ferric nitrate as a nitro source. The method is simple and green, and a series of aryl boride compounds Ipso-nitration products can be obtained in high yields by one-pot reaction. The method uses cheap ferric nitrate as a nitro source, and the reaction conditions are universal. Different types of aryl boride, such as arylboronic acid, aryl pinacol ester and aryl potassium trifluoroborate, can be reacted. The reaction time is short, and the reaction can be completed in only 2h, and the yield is relatively high. The reaction is insensitive to both air and water, and the obtained product has stable properties and a higher yield.

[0010] The present invention is based on electrochemical reaction conditions, generates free radicals by direct oxidation on the electrode surface, obtains intermediate free radicals by free radical addition, and further obtains the target compound by anodic oxidation. The unique electronic environment is also helpful for studying the electron transfer process in the free radical reaction.

[0011] The specific method comprises the following steps: using an aryl boride compound as a starting material, ferric nitrate as a nitrating agent, adding an electrolyte, acetic acid as an additive, mixing with a solvent, setting positive and negative electrodes, reacting under power and heating conditions, and after the reaction is completed, purifying to obtain a nitration product of the aryl boride compound;

[0012] The positive and negative electrode materials are each independently one of precious metals, transition metals, and carbon materials;

[0013] The electrolyte is one of tetrabutylammonium hexafluorophosphate, lithium perchlorate, and tetrabutylammonium tetrafluoroborate;

[0014] The general formula of the aryl boride compound is:

[0015]

[0016] The structural formula of the nitration product obtained is:

[0017] In the formula: R is any one of hydrogen, C2-C6 alkyl, C2-C6 alkoxy, carbonyl functional group, halogen, and aryl.

[0018] Preferably, the aryl boride is any one of the following compounds:

[0019]

[0020] The molar ratio of the aryl boride, ferric nitrate, tetrabutylammonium tetrafluoroborate and acetic acid is 1: (1.0-2.0): (0.5-1.0): (0-10.0).

[0021] Preferably, the molar ratio of aryl boride, ferric nitrate, tetrabutylammonium tetrafluoroborate, and acetic acid is 1:(1.0-2.0):(0.5-1.0):(1-3.0).

[0022] Preferably, the solvent is one of acetonitrile, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide, ethanol, acetone, and dichloromethane.

[0023] Preferably, the positive and negative electrodes are one of Pt(+) / Pt(-), Pt(+) / C(-), C(+) / C(-), C(+) / Pt(-), CF carbon fiber (+) / Pt(-); the most preferred is Pt(+) / Pt(-).

[0024] Preferably, the electrolyte is tetrabutylammonium tetrafluoroborate.

[0025] Preferably, the concentration of the aryl boride is 0.06 to 0.12 mol / L.

[0026] Preferably, the current is 10-20 mA, the heating reaction temperature is 50-90° C., and the reaction time is 1.5-2.5 hours; more preferably, the current is 15 mA, the heating reaction temperature is 70° C., and the reaction time is 2 hours.

[0027] Specifically, the purification process includes: washing with sodium thiosulfate solution, extraction with ethyl acetate, washing with brine, drying with anhydrous sodium sulfate, concentration under reduced pressure, and column chromatography.

[0028] The specific mechanism may be: aryl boride and ferric nitrate are oxidized at anodize to generate aryl boride radicals and nitro radicals, respectively. The aryl boride radicals and nitro radicals undergo addition reaction to form intermediate radicals, which are further oxidized at anodize to obtain the nitration product of aryl boride Ipso-nitration.

[0029] Through the above technical solution, the present invention achieves the following beneficial effects:

[0030] The preparation method of the present invention is simple and green, providing a series of nitration products of the Ipso nitration of aryl boride compounds in high yields through a one-pot reaction. This method utilizes clean electrical energy as the driving force and utilizes less reactive and more stable organoboron reagents, significantly improving substrate applicability and functional group tolerance. It offers advantages such as readily available reagents, simple operation, high yields, and environmental friendliness, providing a new, green and efficient pathway for the Ipso nitration of aryl boride compounds.

[0031] 2. This method successfully achieved the Ipso-nitration of aryl borides using aryl borides of varying structures as raw materials, ferric nitrate as the nitrating agent, tetrabutylammonium tetrafluoroborate as the electrolyte, acetic acid as the additive, and selected positive and negative electrodes. The reaction was carried out at a set current and 70°C. This method utilizes readily available reagents, is simple to operate, and exhibits high atom economy, broadening the scope of Ipso-nitration reactions of aryl borides. DETAILED DESCRIPTION

[0032] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0033] In the following examples, the methods described are conventional methods unless otherwise specified. Some of the raw materials were obtained from publicly available commercial sources, while others were homemade using known methods. In the column chromatography steps of the following examples, the column used was filled with 200-300 mesh silica gel, with specifications of 2 cm diameter x 30 cm height.

[0034] Example 1

[0035] The synthesis route of the Ipso-nitration product of p-methylphenylboronic acid shown in formula III-aa is as follows:

[0036]

[0037] The above reaction equation is the synthesis of Ipso-nitration of p-methylphenylboronic acid:

[0038] To the reactor were added p-methylphenylboric acid (41.6 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid (mass fraction 36%). The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 39.0 mg of p-methylnitrobenzene shown in III-aa was obtained as a light yellow oil by column chromatography, with a yield of 95%.

[0039] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.02(d,J=8.8Hz,2H),7.23(d,J=8.0Hz,2H),2.37(s,3H) 13 C NMR (100MHz, CDCl3) δ146.0, 129.8, 123.4, 21.5.

[0040] The compound synthesized by structural identification is the target compound III-aa shown as p-methylnitrobenzene.

[0041] In the above reaction, with other conditions unchanged, only the effect of current intensity on the yield of methylnitrobenzene is studied:

[0042] When no electricity is applied, no p-methylnitrobenzene is produced; when a current of 10 mA is used, the yield of the product p-methylnitrobenzene is 77%; when a current of 20 mA is used, the yield of the product p-methylnitrobenzene is 76%.

[0043] In the above reaction, with other conditions unchanged, the effect of electrode materials on yield is studied:

[0044] When C(+) / Pt(-) is used as the positive and negative electrodes, the yield of the product p-methylnitrobenzene is 91%; when C(+) / C(-) is used as the positive and negative electrodes, the yield of the product p-methylnitrobenzene is 92%; when Pt(+) / C(-) is used as the positive and negative electrodes, the yield of the product p-methylnitrobenzene is 90%; when CF(+) / Pt(-) is used as the positive and negative electrodes, the yield of the product p-methylnitrobenzene is 67%.

[0045] In the above reaction, with other conditions unchanged, the effect of solvent on yield:

[0046] When 4.5 mL of N,N-dimethylformamide was selected as the solvent, the yield of the product p-methylnitrobenzene was 7%; when 4.5 mL of dimethyl sulfoxide was selected as the solvent, the yield of the product p-methylnitrobenzene was 0%; when 4.5 mL of toluene was selected as the solvent, the yield of the product p-methylnitrobenzene was 0%; when 4.5 mL of ethanol was selected as the solvent, the yield of the product p-methylnitrobenzene was 3%; when 4.5 mL of dichloromethane was selected as the solvent, the yield of the product p-methylnitrobenzene was 64%; and when 4.5 mL of tetrahydrofuran was selected as the solvent, the yield of the product p-methylnitrobenzene was 62%.

[0047] In the above reaction, with other conditions unchanged, the effect of the amount of additive acetic acid on the yield is:

[0048] Without the additive acetic acid, the yield of the product p-methylnitrobenzene was 71%; when 1 mL of acetic acid was selected as the additive, the yield of the product p-methylnitrobenzene was 64%; when 0.5 mL of acetic acid was selected as the additive, the yield of the product p-methylnitrobenzene was 93%.

[0049] In the above reaction, with other conditions unchanged, the effect of electrolyte type on yield is:

[0050] When there is no electrolyte, the yield of the product p-methylnitrobenzene is 40%; when the electrolyte tetrabutylammonium iodide (56 mg, 0.15 mmol) is selected, the yield of the product p-methylnitrobenzene is 0%; when the electrolyte tetrabutylammonium hexafluorophosphate (59.3 mg, 0.15 mmol) is selected, the yield of the product p-methylnitrobenzene is 75%; when the electrolyte lithium perchlorate (16.1 mg, 0.15 mmol) is selected, the yield of the product p-methylnitrobenzene is 81%.

[0051] In the above reaction, with other conditions unchanged, the effect of reaction time on yield is:

[0052] When the reaction time is selected as 1 hour, the yield of the product p-methylnitrobenzene is 64%; when the reaction time is selected as 1.5 hours, the yield of the product p-methylnitrobenzene is 90%; when the reaction time is selected as 2 hours, the yield of the product p-methylnitrobenzene is 91%; when the reaction time is selected as 2.5 hours, the yield of the product p-methylnitrobenzene is 90%.

[0053] In the above reaction, with other conditions unchanged, the effect of reaction temperature on yield is:

[0054] When the reaction temperature is selected as 25°C, the yield of the product p-methylnitrobenzene is 46%; when the reaction temperature is selected as 50°C, the yield of the product p-methylnitrobenzene is 74%; when the reaction temperature is selected as 90°C, the yield of the product p-methylnitrobenzene is 87%.

[0055] In the above reaction, with other conditions unchanged, the effect of nitro source on yield is:

[0056] When sodium nitrite is selected as the nitro source, p-methylnitrobenzene is not generated; when bismuth nitrate is selected as the nitro source, the yield of the product p-methylnitrobenzene is 49%.

[0057] Example 2

[0058] The synthesis route of the Ipso-nitration product of phenylboronic acid shown in formula III-ba is as follows:

[0059]

[0060] The above reaction equation is the synthesis of phenylboronic acid Ipso-nitration:

[0061] Phenylboric acid (37.7 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, acetonitrile 4.5 mL, and acetic acid 0.1 mL were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 32.5 mg of nitrobenzene represented by III-ba was obtained as a light yellow oil by column chromatography, with a yield of 88%.

[0062] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.18 (d, J = 5.2Hz, 2H), 7.71 (m, 1H), 7.55-7.51 (m, 2H). 13 C NMR (100MHz, CDCl3) δ148.0, 134.6, 129.2, 123.2.

[0063] The compound synthesized by structural identification is nitrobenzene represented by the target compound III-ba.

[0064] Example 3

[0065] The synthesis route of the Ipso-nitration product of p-fluorophenylboronic acid shown in formula III-ca is as follows:

[0066]

[0067] The above reaction equation is the synthesis of Ipso-nitration of 4-fluorophenylboronic acid:

[0068] To the reactor were added p-fluorophenylboric acid (42.8 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 34.3 mg of p-fluoronitrobenzene (III-ca) was obtained as a light yellow oil by column chromatography, with a yield of 81%.

[0069] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.31-8.27(m,2H),7.26-7.22(m,2H). 13C NMR (100MHz, CDCl3) δ 167.5 (d, J = 256Hz), 144.3, 126.4 (d, J = 10.1Hz), 116.5 (d, J = 23.6Hz).

[0070] The compound synthesized after structural identification is the target compound III-ca shown as p-fluoronitrobenzene.

[0071] Example 4

[0072] The synthesis route of the Ipso-nitration product of p-chlorophenylboronic acid shown in formula III-da is as follows:

[0073]

[0074] The above reaction equation is the synthesis of Ipso-nitration of p-chlorophenylboronic acid:

[0075] To the reactor were added p-chlorophenylboric acid (47.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 40.5 mg of p-chloronitrobenzene shown in III-da was obtained by column chromatography as a light yellow solid with a yield of 86%.

[0076] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.20 (d, J = 8.8 Hz, 2H), 7.56-7.47 (d, J = 8.8 Hz, 2H). 13 C NMR (100MHz, CDCl3) δ146.4, 141.4, 129.6, 124.9.

[0077] The compound synthesized after structural identification is the target compound III-da shown as p-chloronitrobenzene.

[0078] Example 5

[0079] The synthesis route of the Ipso-nitration product of p-bromophenylboronic acid shown in formula III-ea is as follows:

[0080]

[0081] The above reaction equation is the synthesis of Ipso-nitration of p-bromophenylboronic acid:

[0082] To the reactor were added p-bromophenylboric acid (61.5 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 58.5 mg of p-bromonitrobenzene shown as III-ea was obtained by column chromatography as a light yellow solid with a yield of 97%.

[0083] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.11 (d, J = 8.8 Hz, 2H), 7.70 (d, J = 8.8 Hz, 2H). 13 C NMR (100MHz, CDCl3) δ146.9, 132.6, 130.0, 125.0.

[0084] The compound synthesized after structural identification is the target compound III-ea shown as p-bromonitrobenzene.

[0085] Example 6

[0086] The synthesis route of the Ipso-nitration product of 3-fluoro-phenylboronic acid shown in formula III-fa is as follows:

[0087]

[0088] The above reaction equation is the synthesis of Ipso-nitration of 3-fluoro-phenylboronic acid:

[0089] 3-Fluoro-phenylboric acid (43.3 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 35.1 mg of 3-fluoro-nitrobenzene represented by III-fa was obtained by column chromatography as a yellow oil with a yield of 83%.

[0090] The results of structure confirmation are as follows: 1H NMR (400MHz, CDCl3) δ8.06 (d, J = 8.4Hz, 1H), 7.90 (m, 1H), 7.55 (q, J = 22.0Hz, 1H), 7.42 (t, J = 16.0Hz, 1H). 13 C NMR (100MHz, CDCl3) δ 163.4 (d, J = 249.2Hz), 148.9 (d, J = 2.7Hz), 130.8 (d, J = 8.2Hz), 122.0 (d, J = 21.2Hz), 119.2 (d, J = 3.6Hz), 111.1 (d, J = 22.6Hz).

[0091] The synthesized compound was identified by structure as 3-fluoro-nitrobenzene represented by the target compound III-fa.

[0092] Example 7

[0093] A 1pso-nitration product of 3-chloro-phenylboronic acid as shown in formula III-ga, the synthesis route of which is as follows:

[0094]

[0095] The above reaction equation is the synthesis of Ipso-nitration of 3-chloro-phenylboronic acid:

[0096] 3-Chloro-phenylboronic acid (47.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, acetonitrile 4.5 mL, and acetic acid 0.1 mL were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 41.0 mg of 3-chloro-nitrobenzene represented by III-ga was obtained by column chromatography as a yellow oil with an 87% yield.

[0097] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.22(t,J=4.4Hz,1H),8.14(dd,J=1.2,1.0Hz,1H),7.70(dd,J=7.2,1.2Hz,1H),7.54(t,J=16.4Hz,1H). 13 C NMR (100MHz, CDCl3) δ148.7, 135.3, 134.7, 130.4, 123.8, 121.7.

[0098] The compound synthesized by structural identification is 3-chloro-nitrobenzene shown as the target compound III-ga.

[0099] Example 8

[0100] A 1pso-nitration product of 3-bromo-phenylboronic acid as shown in formula III-ha has the following synthesis route:

[0101]

[0102] The above reaction equation is the synthesis of Ipso-nitration of 3-bromo-phenylboronic acid:

[0103] 3-Bromo-phenylboronic acid (47.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, acetonitrile 4.5 mL, and acetic acid 0.1 mL were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 39.2 mg of 3-bromo-nitrobenzene shown as III-ha was obtained as a light yellow oil by column chromatography, with a yield of 65%.

[0104] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.38(t,J=7.6Hz,1H),8.19(dd,J=2.4,1.6Hz,1H),7.85(d,J=8.8Hz,1H),7.47(t,J=16.4Hz,1H). 13 C NMR (100MHz, CDCl3) δ148.7, 137.6, 130.6, 126.7, 122.8, 122.1.

[0105] The synthesized compound was identified by structure as the target compound III-ha, 3-bromo-nitrobenzene.

[0106] Example 9

[0107] The synthesis route of the Ipso-nitration product of 3-methyl-phenylboronic acid shown in formula III-ia is as follows:

[0108]

[0109] The above reaction equation is the synthesis of Ipso-nitration of 3-methyl-phenylboronic acid:

[0110] 3-Methyl-phenylboronic acid (41.6 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, acetonitrile 4.5 mL, and acetic acid 0.1 mL were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 30.8 mg of 3-methyl-nitrobenzene shown in III-ia was obtained by column chromatography as a light yellow oil with a yield of 75%.

[0111] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.01-7.99 (m, 2H), 7.51 (d, J = 7.6Hz, 1H), 7.41 (t, J = 15.2Hz, 1H), 2.48 (s, 3H). 13 C NMR (100MHz, CDCl3) δ148.1,139.8,135.3,129.0,123.7,120.6,21.1.

[0112] The compound synthesized after structural identification is 3-methyl-nitrobenzene shown as the target compound III-ia.

[0113] Example 10

[0114] A 1pso-nitration product of 4-ethyl-phenylboronic acid as shown in formula III-ja has the following synthesis route:

[0115]

[0116] The above reaction equation is the synthesis of Ipso-nitration of 4-ethyl-phenylboronic acid:

[0117] 4-Ethyl-phenylboronic acid (45.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 43.9 mg of 4-ethyl-nitrobenzene shown in III-ja was obtained by column chromatography as a yellow oil with a yield of 97%.

[0118] The results of structure confirmation are as follows: 1H NMR (400MHz, CDCl3) δ8.12-7.81(m,2H),7.33-7.35(m,2H),2.73(q,J=22.8Hz,2H),1.25(t,J=15.2Hz,3H). 13 C NMR (100MHz, CDCl3) δ152.0, 146.1, 128.6, 123.6, 28.8, 15.0.

[0119] The compound synthesized by structural identification is 4-ethyl-nitrobenzene shown as the target compound III-ja.

[0120] Example 11

[0121] A 1pso-nitration product of 4-(bromomethyl)phenylboronic acid as shown in formula III-ka has the following synthesis route:

[0122]

[0123] The above reaction equation is the synthesis of Ipso-nitration of 4-(bromomethyl)phenylboronic acid:

[0124] 4-(Bromomethyl)phenylboronic acid (65.5 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 56.1 mg of 4-(bromomethyl)nitrobenzene shown in III-ka was obtained by column chromatography as a light yellow solid with a yield of 87%.

[0125] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.20 (d, J = 8.8 Hz, 2H), 7.58 (d, J = 14 Hz, 2H), 4.53 (s, 2H). 13 C NMR (100MHz, CDCl3) δ147.6, 144.8, 129.9, 124.0, 31.0.

[0126] The compound synthesized after structural identification is the target compound III-ka shown as 4-(bromomethyl)nitrobenzene.

[0127] Example 12

[0128] The Ipso-nitration product of a phenylboronic acid pinacol ester as shown in formula III-1a has the following synthesis route:

[0129]

[0130] The above reaction equation is the synthesis of Ipso-nitration of phenylboronic acid pinacol ester:

[0131] Phenylboronic acid pinacol ester (61.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 18.9 mg of nitrobenzene shown in III-1a was obtained as a light yellow oil by column chromatography, with a yield of 51%.

[0132] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.18 (d, J = 5.2Hz, 2H), 7.71 (m, 1H), 7.55-7.51 (m, 2H). 13 C NMR (100MHz, CDCl3) δ148.0, 134.6, 129.2, 123.2.

[0133] The compound synthesized after structural identification is the nitrobenzene shown as the target compound III-la.

[0134] Example 13

[0135] The synthesis route of the Ipso-nitration product of p-bromophenylboronic acid pinacol ester shown in formula III-ma is as follows:

[0136]

[0137] The above reaction equation is the synthesis of Ipso-nitration of p-bromophenylboronic acid pinacol ester:

[0138] To the reactor were added p-bromophenylboronic acid pinacol ester (86.6 mg, 0.3 mmol), ferric nitrate nonahydrate (23.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 42.6 mg of p-bromonitrobenzene shown in III-ma was obtained by column chromatography as a light yellow solid with a yield of 71%.

[0139] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.11 (d, J = 8.8 Hz, 2H), 7.70 (d, J = 8.8 Hz, 2H). 13 C NMR (100MHz, CDCl3) δ146.9, 132.6, 130.0, 125.0.

[0140] The compound synthesized after structural identification is the target compound III-ma shown as p-bromonitrobenzene.

[0141] Example 14

[0142] The synthesis route of the Ipso-nitrated product of p-methylphenylboronic acid pinacol ester shown in formula III-na is as follows:

[0143]

[0144] The above reaction equation is the synthesis of Ipso-nitration of p-methylphenylboronic acid pinacol ester:

[0145] To the reactor were added p-methylphenylboronic acid pinacol ester (66.8 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, the mixture was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 21.8 mg of p-methylnitrobenzene (shown as III-na) was obtained as a light yellow oil by column chromatography, with a yield of 53%.

[0146] The results of structure confirmation are as follows: 1H NMR (400MHz, CDCl3) δ8.02(d,J=8.8Hz,2H),7.23(d,J=8.0Hz,2H),2.37(s,3H) 13 C NMR (100MHz, CDCl3) δ146.0, 129.8, 123.4, 21.5.

[0147] The compound synthesized after structural identification is the target compound III-na represented by p-methylnitrobenzene.

[0148] Example 15

[0149] The synthesis route of the Ipso-nitrated product of potassium phenyltrifluoroborate shown in formula III-oa is as follows:

[0150]

[0151] The above reaction equation is the synthesis of Ipso-nitration of potassium phenyl trifluoroborate:

[0152] Potassium phenyltrifluoroborate (56.9 mg, 0.3 mmol), ferric nitrate nonahydrate (123.7 mg, 0.3 mmol), tetrabutylammonium tetrafluoroborate (50.4 mg, 0.15 mmol), Pt(+) / Pt(-) as positive and negative electrodes, 4.5 mL of acetonitrile, and 0.1 mL of acetic acid were added to the reactor in sequence. The reaction solution was reacted at a current of 15 mA and 70°C for 2 h. After the reaction, it was washed with sodium thiosulfate solution, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 21.4 mg of nitrobenzene shown in III-oa was obtained by column chromatography as a light yellow oil with a yield of 58%.

[0153] The results of structure confirmation are as follows: 1 H NMR (400MHz, CDCl3) δ8.18 (d, J = 5.2Hz, 2H), 7.71 (m, 1H), 7.55-7.51 (m, 2H). 13 C NMR (100MHz, CDCl3) δ148.0, 134.6, 129.2, 123.2.

[0154] The compound synthesized after structural identification is the target compound III-oa, nitrobenzene.

[0155] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0156] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0157] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An electrochemical method for achieving Ipso-nitration of arylborides using ferric nitrate as a nitro source, comprising the following steps: Using aryl boride compounds as starting materials, ferric nitrate as a nitrating agent, adding electrolytes, acetic acid as an additive, mixing with a solvent, setting positive and negative electrodes, and reacting under power and heating conditions. After the reaction is completed, the aryl boride Ipso-nitration is obtained after purification. The molar ratio of the aryl boride, ferric nitrate, electrolyte, and acetic acid is 1:(1.0-2.0):(0.5-1.0):(0-10.0); the electrolyte is one of tetrabutylammonium hexafluorophosphate, lithium perchlorate, and tetrabutylammonium tetrafluoroborate; The general formula of the aryl boride compound is: The structural formula of the nitroation product obtained by the reaction is: In the formula: R is any one of hydrogen, C2-C6 alkyl, C2-C6 alkoxy, C2-C6 halogen, carbonyl functional group, and aryl.

2. The method according to claim 1, characterized in that The aryl boride compound is any one of the following compounds:

3. The method according to claim 1, characterized in that The molar ratio of the aryl boride, ferric nitrate, tetrabutylammonium tetrafluoroborate and acetic acid is 1: (1.0-2.0): (0.5-1.0): (1.0-3.0).

4. The method according to claim 1, wherein The positive and negative electrode materials are each independently one of precious metals, transition metals, and carbon materials.

5. The method according to claim 4, characterized in that The positive and negative electrodes are specifically one of Pt(+) / Pt(-), Pt(+) / C(-), C(+) / C(-), C(+) / Pt(-), and CF(+) / Pt(-).

6. The method according to claim 1, characterized in that The current is 10~20mA.

7. The method according to claim 1, characterized in that The solvent is one of acetonitrile, tetrahydrofuran, N,N-dimethylformamide, ethanol, acetone and dichloromethane.

8. The method according to claim 1, characterized in that The concentration of the aryl boron compound in the solvent is 0.06 to 0.12 mol / L.

9. The method according to any one of claims 1 to 8, characterized in that The heating temperature is 50-90°C and the reaction time is 1.5-2.5 hours.

10. The method according to any one of claims 1 to 8, characterized in that The purification process includes: washing with sodium thiosulfate solution, extraction with ethyl acetate, washing with brine, drying with anhydrous sodium sulfate, concentrating under reduced pressure, and column chromatography.

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