Method for electrocatalytic synthesis of nitrile compounds using thianthrenium salt as substrate

Abstract

The present invention belongs to the field of organic synthesis technology and discloses a method for electrocatalytically synthesizing nitrile compounds using thianthrenium salts as substrates. The method comprises the following steps: using thianthrenium salts and p-toluenesulfonyl nitrile as substrates, with both the anode and cathode being carbon electrodes, connecting a DC regulated power supply in an electrolyte and an organic solvent, and performing an electrolytic reaction at room temperature with stirring for 6 to 8 hours to obtain nitrile compounds. The thianthrenium salts are arylthianthrenium salts or heterocyclic thianthrenium salts, and the nitrile compounds are aromatic nitrile compounds or heterocyclic nitrile compounds. The method has a wide substrate universality range, the raw material TsCN is inexpensive and readily available, the reaction conditions are mild, no excess metal waste is generated, and it conforms to the concept of green chemistry and is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for electrocatalytically synthesizing nitrile compounds using thianthrenium salts as substrates. Background Art

[0002] Aryl nitriles are an important class of organic compounds with widespread applications in natural products, pharmaceuticals, pesticides, materials, and dyes. The small size and strong electron-withdrawing properties of the cyano group enable nitrile compounds to penetrate deep into target proteins and form strong hydrogen bonds with key amino acids in the active site. Consequently, aryl nitriles and their derivatives possess a wide range of physiological activities. In medicinal chemistry, many approved drugs, such as the anti-HIV drug etravirine, the anti-schizophrenia drug periciazine, the anti-breast cancer drug fadrozole, and the antidepressant citalopram, all possess aryl nitriles as key functional groups. Furthermore, nitrile compounds can be readily converted to other functional groups, such as amines, carboxylic acids, aldehydes, ketones, amides, and various heterocyclic backbones, making them invaluable intermediates in organic synthesis.

[0003] Currently, aryl nitriles can be synthesized by the following methods.

[0004] 1) Rosenmund-von Braun reaction: An aryl halide and excess cuprous cyanide are refluxed in a high-boiling polar solvent (such as DMF, nitrobenzene, and pyridine) to produce an aryl nitrile. This reaction first involves an oxidative addition reaction between the aryl halide and cuprous cyanide to produce a Cu(III) intermediate. This is followed by a reductive elimination reaction to afford the aryl nitrile. However, this reaction has the disadvantages of requiring purification due to the presence of excess cuprous cyanide and the polar, high-boiling solvent. Furthermore, the reaction requires high reaction temperatures and a high tolerance for the functional groups of the substrate (reference: K. W. Rosenmund and E. Struck, Das am Ringkohlenstoff gebundene Halogen undsein Ersatz durch andere Substituenten. I. Mitteilung: Ersatz des Halogens durch die Carboxylgruppe, Ber. Dtsch. Chem. Ges. B, 1919, 52, 1749–1756).

[0005] 2) Sandmeyer Reaction: This reaction first requires the reaction of an aromatic primary amine (generally at 0-5°C) with a strong acid solution (hydrochloric acid or sulfuric acid) of sodium nitrite to form a diazonium salt. The diazonium salt then reacts with an aqueous solution of cuprous cyanide in potassium cyanide at 60-70°C to form the aromatic nitrile. The drawback of this reaction is not only the harsh reaction conditions but also the use of stoichiometric amounts of highly toxic cuprous cyanide (see: T. Sandmeyer, Ueber die Ersetzung der Amid-gruppe durch Chlor, Brom und Cyan in den aromatictischen Substanzen, Ber. Dtsch. Chem. Ges., 1884, 17, 2650–2653).

[0006] 3) Palladium-catalyzed synthesis of aromatic nitriles from aldoximes: This reaction utilizes aldoxime as a substrate. The N-O bond reacts with Pd(0) via oxidative addition, followed by β-H elimination to form the aromatic nitriles. However, this method is only applicable to most trans-oximes, the reaction substrates are relatively limited, and the use of Pd(0) is relatively expensive (reference: H.S. Kim, S.H. Kim, J.N. Kim, Tetrahedron Lett. 2009, 50, 1717-1719).

[0007] 4) Synthesis of Aryl Nitriles by Cyanidation with Organometallic Reagents: Electrophilic cyanidation with organometallic reagents (lithium, magnesium, and zinc reagents) is an important complementary pathway for the synthesis of aryl nitriles. For example, an arene can be metallated with tert-butyl lithium, followed by electrophilic cyanidation of the benzocyanate with the arene to produce the aryl nitrile (reference: N. Sato, Tetrahedron Lett. 2002, 43, 6403-6404).

[0008] 5) Palladium-catalyzed cyanation of aryl halides and pseudohalides: In this reaction, Pd(II) undergoes electrophilic palladiumation with aryl halides, followed by migratory insertion of isocyanide to form a key imine-based Pd intermediate. The final intermediate eliminates isobutylene to give the aryl nitrile (Reference: X. Jiang, J.-M. Wang, Y. Zhang, Z. Chen, Y.-M. Zhu, S.-J. Ji, Tetrahedron 2015, 71, 4883-4887.).

[0009] In summary, the most commonly used synthesis methods for aromatic nitrile compounds are still the Rosenmund-von Braun reaction and the Sandmeyer reaction. However, both reactions require a large amount of highly toxic cuprous cyanide, and the reaction conditions are harsh and easily cause heavy metal pollution to the environment.

[0010] In recent years, transition metal-catalyzed cyanation of aromatic halides has been developed to synthesize aromatic nitriles. However, the inorganic cyanide source used in this method can easily generate highly toxic HCN during use, and the reaction produces a large amount of metal waste, causing environmental pollution and waste of resources, making it unsuitable for industrial production. Therefore, the development of a new method for synthesizing nitrile compounds is of great significance. Summary of the Invention

[0011] The present invention addresses the technical problem that the existing synthesis process of nitrile compounds produces highly toxic substances and waste residues, which is not conducive to industrial production. It provides a method for electrocatalytically synthesizing nitrile compounds using thianthrenium salts as substrates. The substrate has a wide universal range, the raw material TsCN is cheap and easily available, the reaction conditions are mild, no excess metal waste is generated, the method conforms to the concept of green chemistry, and is suitable for industrial production.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] The invention provides a method for electrocatalytically synthesizing nitrile compounds using a thianthrenium salt as a substrate. The method comprises the following steps: using a thianthrenium salt and p-toluenesulfonyl nitrile as substrates, using carbon electrodes as both the anode and the cathode, connecting a DC regulated power supply in an electrolyte and an organic solvent, and performing an electrolytic reaction with stirring at room temperature for 6 to 8 hours to obtain a nitrile compound; the thianthrenium salt is an aryl thianthrenium salt or a heterocyclic thianthrenium salt, and the nitrile compound is an aromatic nitrile compound or a heterocyclic nitrile compound.

[0014] Preferably, the ortho, meta and / or para positions of the aromatic group in the arylthianthrenium salt are substituted by halogen, ester, acyl, cyano, trifluoromethyl, phenyl, benzyloxy, alkyl or alkoxy.

[0015] Preferably, the heterocyclic thianthrenium salt is a pyridinium thianthrenium salt, a thienyl thianthrenium salt or a benzo[d][1,3]dioxolyl 5-thianthrenium salt.

[0016] Preferably, the organic solvent is selected from one of THF, DMSO, MeOH, NMP or DMF.

[0017] Preferably, the electrolyte is selected from n-Bu4NClO4, n One of Bu4NPF6, Et4NOTs or LiClO4.

[0018] Preferably, the molar ratio of the thianthrenium salt to p-toluenesulfonyl nitrile is 1:(1-5).

[0019] Preferably, the molar ratio of the thianthrenium salt to the electrolyte is 1:(1-4).

[0020] Preferably, the ratio of the thianthrenium salt to the organic solvent is 1 mmol: (4-12) mL.

[0021] Preferably, the voltage of the DC regulated power supply is -1.5V to -2.5V.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention uses thianthrenium salts as substrates, such as arylthianthrenium salts or heterocyclic thianthrenium salts, to synthesize aromatic nitrile compounds or heterocyclic nitrile compounds under electrocatalytic conditions. The substrate has a wide range of universality, broadening the synthesis methods of nitrile compounds. The raw material TsCN is cheap and easily available, and it is easy to achieve industrial production.

[0024] 2. The present invention adopts an electrochemical method, reacts at room temperature, has mild reaction conditions, does not produce excess metal waste, has no complicated intermediate links, is simple and safe to operate, and conforms to the concept of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The diagram is a reaction principle diagram for the synthesis of aromatic nitrile compounds according to the present invention, wherein 1 represents an aryl thianthrenium salt, 2 represents p-toluenesulfonyl nitrile, and 3 represents an aryl nitrile. DETAILED DESCRIPTION

[0026] The following examples are used to illustrate the present invention but are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are all conventional methods unless otherwise specified.

[0027] The thianthrenium salts used in the embodiments of the present invention can be prepared according to the literature method (R.-C. Sang, S.-E. Korkis, W.-Q. Su, F. Ye, Engl, P.-S., Berger, F., Ritter, T. Angew. Chem. Int. Ed. 2019, 58, 16161-16166; 2) F. Ye, Berger, F., H. Jia, Ford, J., Wortman, A., s J,Genicot,C.,Ritter,T.Angew.Chem.Int.Ed.2019,58,14615–14619; 3)C.Chen,M.-Y.Wang,H.-J.Lu,B.-L.Zhao,Z.-Z.Shi.Angew.Chem.Int.Ed.2021,60,21756-21760.).

[0028] The present invention uses an arylthianthrenium salt 1 and p-toluenesulfonyl nitrile 2 to synthesize an aromatic nitrile compound 3 in the following reaction process:

[0029]

[0030] like Figure 1 As shown, the thianthrenium salt is reduced to carbon radical I at the cathode, and carbon radical I replaces the substrate TsCN to obtain a nitrile group.

[0031] Example 1 Synthesis of benzonitrile

[0032]

[0033] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. Phenylthianthrenium salt 1a (0.5 mmol), TsCN (0.6 mmol, 109 mg), electrolyte n-Bu₄NClO₄ (137 mg), and DMF (2 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature with magnetic stirring at -1.5 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 40.2 mg of a colorless oily liquid in a 78% yield. 1 H NMR (500MHz, Chloroform-d) δ7.68–7.64(m,2H),7.64–7.59(m,1H),7.48(t,J=7.9Hz,2H); 13 C NMR (126MHz, CDCl3) δ132.8, 132.1, 129.2, 118.9, 112.4.

[0034] Example 2 Synthesis of 4-bromobenzonitrile

[0035]

[0036] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 4-Bromophenylthianthrenium salt 1b (0.5 mmol), TsCN (1.0 mmol, 181.2 mg), electrolyte n-Bu₄NClO₄ (137 mg), and DMF (3 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature with magnetic stirring at -1.5 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 63.9 mg of a colorless oily liquid in a 71% yield. 1 H NMR (500MHz, CDCl3) δ7.68–7.62(m,2H),7.60–7.51(m,2H); 13 CNMR (126MHz, CDCl3) δ133.4,132.7,128.0,118.1,111.3.

[0037] Example 3 Synthesis of 4-(trifluoromethyl)benzonitrile

[0038]

[0039] A diaphragmless electrolytic cell was selected, equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm), and connected to a DC regulated power supply. 4-(trifluoromethyl)phenylthianthrenium salt 1c (0.5 mmol), TsCN (1.0 mmol, 181.2 mg), and electrolyte were added to the electrolytic cell. n Bu4NPF6 (387.4 mg) and THF (4 mL) were added. Electrolysis was carried out at room temperature for 7 h under magnetic stirring, connected to a V = -2.0 V power supply. When TLC analysis indicated that the electrolysis of the starting material was complete, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL x 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (V:V = 50:1) as eluent to obtain 67.5 mg of a colorless oily liquid in a 79% yield. 1 H NMR (500MHz, CDCl3) δ7.83 (d, J = 8.3 Hz, 2H), 7.78 (d, J = 8.3 Hz, 2H); 13C NMR (101MHz, CDCl3) δ 134.5 (q, J = 26.9Hz), 132.7, 126.2 (q, J = 9.1Hz), 123.1 (q, J = 219.0Hz), 117.4, 116.1. 19 F NMR (471 MHz, CDCl3) δ-63.6.

[0040] Example 4 Synthesis of terephthalonitrile

[0041]

[0042] A diaphragmless electrolytic cell was selected, equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm), and connected to a DC regulated power supply. 4-(Cyano)phenylthianthrenium salt 1d (0.5 mmol), TsCN (1.5 mmol, 271.8 mg), and electrolyte were added to the electrolytic cell. n Bu4NPF6 (387.4 mg) and DMSO (5 mL) were added. Electrolysis was carried out at room temperature for 7 h under magnetic stirring with a V = -2.0 V power supply. When TLC analysis indicated that the electrolysis of the starting material was complete, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL x 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (V:V = 40:1) as eluent to obtain 48.6 mg of a colorless oily liquid in a 76% yield. 1 H NMR (500MHz, CDCl3) δ7.82 (d, J = 1.2Hz, 4H); 13 C NMR (126MHz, CDCl3) δ132.8, 117.0, 116.7.

[0043] Example 5 Synthesis of methyl 4-cyanobenzoate

[0044]

[0045] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 4-(Methylformyl)phenylthianthrenium salt 1e (0.5 mmol), TsCN (1.5 mmol, 271.8 mg), electrolyte Et4NOTs (452.1 mg), and NMP (5 mL) were added to the cell. The electrolysis reaction was conducted for 8 h at room temperature with magnetic stirring at -2.5 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 30:1) as the eluent to afford 60.0 mg of a colorless oily liquid in a 72% yield. 1 H NMR (500MHz, CDCl3) δ8.18–8.11(m,2H),7.83–7.70(m,2H),3.96(s,3H); 13 C NMR (126MHz, CDCl3) δ165.4,133.9,132.2,130.1,118.0,116.4,52.7.

[0046] Example 6 Synthesis of 4-acetylbenzonitrile

[0047]

[0048] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 4-(Acetyl)phenylthianthrenium salt 1f (0.5 mmol), TsCN (2 mmol, 362.4 mg), the electrolyte Et4NOTs (452.1 mg), and DMF (6 mL) were added to the cell. The electrolysis reaction was conducted for 8 h at room temperature with magnetic stirring at -2.5 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 40:1) as the eluent to afford 55.1 mg of a colorless oily liquid in a 76% yield. 1 H NMR (500MHz, CDCl3) δ8.13–8.02(m,2H),7.87–7.72(m,2H),2.67(s,3H); 13 C NMR (126MHz, CDCl3) δ196.5,139.9,132.5,128.7,117.9,116.4,26.8.

[0049] Example 7 Synthesis of 4-methoxybenzonitrile

[0050]

[0051] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 1 g (0.5 mmol) of 4-(methoxy)phenylthianthrenium salt, 2 mmol of TsCN (362.4 mg), the electrolyte LiClO₄ (212.8 mg), and MeOH (6 mL) were added to the cell. The electrolysis reaction was conducted for 6 h at room temperature under magnetic stirring at -1.6 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 53.9 mg of a colorless oily liquid in an 81% yield. 1 H NMR (500MHz, CDCl3) δ7.57 (dd, J=8.8, 1.6Hz, 2H), 6.95 (dd, J=8.8, 1.6Hz, 2H), 3.85 (s, 3H); 13 C NMR (126MHz, CDCl3) δ162.9, 134.0, 119.2, 114.8, 103.9, 55.6.

[0052] Example 8 Synthesis of 4-(Benzyloxy)benzonitrile

[0053]

[0054] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 4-(Benzyloxy)phenylthianthrenium salt 1h (0.5 mmol), TsCN (2.5 mmol, 453 mg), electrolyte LiClO₄ (212.8 mg), and DMSO (2 mL) were added to the cell. The electrolysis reaction was conducted for 6 h at room temperature under magnetic stirring at -1.6 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 85.7 mg of a colorless oily liquid in an 82% yield. 1H NMR (500MHz, CDCl3) δ7.63–7.59(m,2H),7.47–7.33(m,4H),7.42–7.36(m,1H),7.06–7.03(m,2H),5.14(s,2H); 13 C NMR (126MHz, CDCl3) δ162.0,135.7,134.0,128.8,128.5,127.5,119.2,115.6,104.3,70.3.

[0055] Example 9 Synthesis of [1,1'-biphenyl]-4-carbonitrile

[0056]

[0057] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 4-Phenylbenzothianthrenium salt 1i (0.5 mmol), TsCN (2.5 mmol, 453 mg), electrolyte n-Bu4NClO4 (854.8 mg), and DMF (2 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature with magnetic stirring at -1.8 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to yield 67.1 mg of a colorless oily liquid in a 75% yield. 1 H NMR (500MHz, CDCl3) δ7.79–7.74(m,2H),7.74–7.68(m,2H),7.66–7.59(m,2H),7.55–7.48(m,2H),7.49–7.43(m,1H); 13 C NMR (126MHz, CDCl3) δ145.7,139.2,132.6,129.1,128.7,127.8,127.3,119.0,110.9.

[0058] Example 10 Synthesis of isophthalonitrile

[0059]

[0060] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. 3-(Cyano)phenylthianthrenium salt 1j (0.5 mmol), TsCN (0.6 mmol, 109 mg), electrolyte n-Bu4NClO4 (854.8 mg), and DMF (3 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature with magnetic stirring at -1.8 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 40:1) as the eluent to afford 58.7 mg of a colorless oily liquid in a 76% yield. 1 H NMR (500MHz, CDCl3) δ7.98 (s, 1H), 7.93 (d, J = 7.9Hz, 2H), 7.68 (t, J = 7.9Hz, 1H); 13 C NMR (126MHz, CDCl3) δ136.0, 135.4, 130.4, 116.6, 114.2.

[0061] Example 11 Synthesis of 3-methoxybenzonitrile

[0062]

[0063] A non-diaphragm electrolytic cell was equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) and connected to a DC regulated power supply. 3-(Methoxy)phenylthianthrenium salt 1k (0.5 mmol), TsCN (1.0 mmol, 181.2 mg), and electrolyte were added to the electrolytic cell. n Bu4NPF6 (1.16 g) and DMSO (3 mL) were added. Electrolysis was carried out at room temperature for 7 h under magnetic stirring, connected to a V = -2.0 V power supply. When TLC analysis indicated that the electrolysis of the starting material was complete, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL x 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (V:V = 50:1) as eluent to obtain 52.5 mg of a colorless oily liquid in a 79% yield. 1 H NMR (500MHz, CDCl3) δ7.56 (ddd, J=9.7, 5.7, 2.7Hz, 2H), 7.11–6.94 (m, 2H), 3.94 (s, 3H). 13C NMR (126MHz, CDCl3) δ161.3,134.4,133.8,120.8,116.5,111.3,101.8,56.0.

[0064] Example 12 Synthesis of 3,4-dimethylbenzonitrile

[0065]

[0066] A non-diaphragm electrolytic cell was selected, equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm), and connected to a DC regulated power supply. 3,4-(dimethoxy)phenylthianthrenium salt 1L (0.5 mmol), TsCN (1.0 mmol, 181.2 mg), and electrolyte were added to the electrolytic cell. n Bu4NPF6 (1.16 g) and THF (4 mL) were added. Electrolysis was carried out at room temperature for 7 h under magnetic stirring with a V = -2.0 V power supply. When TLC analysis indicated that the electrolysis of the starting material was complete, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL x 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (V:V = 50:1) as eluent to obtain 53.1 mg of a colorless oily liquid in an 81% yield. 1 H NMR (500MHz, CDCl3) δ7.45–7.36 (m, 2H), 7.23 (d, J = 7.7Hz, 1H), 2.34 (s, 3H), 2.30 (s, 3H). 13 C NMR (126MHz, CDCl3) δ142.5,137.9,132.8,130.3,129.6,119.3,109.5,20.1,19.6.

[0067] Example 13 Synthesis of 2-(trifluoromethyl)benzonitrile

[0068]

[0069] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was connected to a DC regulated power supply. 2-(trifluoromethyl)phenylthianthrenium salt 1m (0.5 mmol), TsCN (1.0 mmol, 181.2 mg), electrolyte Et4NOTs (1.05 g), and DMF (4 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature under magnetic stirring at -2.0 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 59.8 mg of a colorless oily liquid in a 70% yield. 1 H NMR (500MHz, CDCl3) δ7.63 (dd, J=7.7, 1.5Hz, 1H), 7.60–7.55 (m, 1H), 7.53 (s, 1H), 7.49 (d, J=8.4Hz, 1H); 13 CNMR (126MHz, CDCl3) δ149.2 (q, J = 1.3Hz), 131.0, 130.6, 125.6, 124.4, 120.2 (q, J = 259.6Hz), 117.2, 114.1. 19 F NMR (471 MHz, CDCl3) δ-58.2.

[0070] Example 14 Synthesis of benzo[d][1,3]dioxin-5-carbonitrile

[0071]

[0072] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was connected to a DC regulated power supply. Benzo[d][1,3]dioxolyl 5-thianthrenium salt 1n (0.5 mmol), TsCN (1.5 mmol, 271.8 mg), Et4NOTs (1.05 g), and DMF (5 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature with magnetic stirring at -2.2 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 58.8 mg of a colorless oily liquid in an 80% yield. 1H NMR (500MHz, CDCl3) δ7.22 (dd, J = 8.1, 1.7Hz, 1H), 7.04 (d, J = 1.7Hz, 1H), 6.87 (d, J = 8.0Hz, 1H), 6.08 (s, 2H); 13 C NMR (126MHz, CDCl3) δ151.6,148.1,128.2,118.9,111.4,109.1,104.9,102.3.

[0073] Example 15 Synthesis of Thiophene-3-Carbonitrile

[0074]

[0075] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was used and connected to a DC regulated power supply. Thiophenethrenium salt 1o (0.5 mmol), TsCN (1.5 mmol, 271.8 mg), electrolyte LiClO₄ (425.6 mg), and DMF (5 mL) were added to the cell. The electrolysis reaction was conducted for 7 h at room temperature under magnetic stirring at -2.2 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 38.9 mg of a colorless oily liquid in a 72% yield. 1 H NMR (500MHz, CDCl3) δ7.96 (dd, J=3.0, 1.2Hz, 1H), 7.45 (dd, J=5.1, 3.0Hz, 1H), 7.32 (dd, J=5.1, 1.2Hz, 1H); 13 C NMR (126MHz, CDCl3) δ135.4, 128.7, 127.4, 115.2, 110.7.

[0076] Example 16 Synthesis of pyridinecarbonitrile

[0077]

[0078] A diaphragmless electrolytic cell equipped with a carbon anode (1 cm × 0.5 cm) and a carbon cathode (1 cm × 0.2 cm) was connected to a DC regulated power supply. Thianthenium pyridine salt 1p (0.5 mmol), TsCN (2 mmol, 363.2 mg), LiClO₄ (425.6 mg), and DMF (6 mL) were added to the cell. The electrolysis reaction was conducted for 8 h at room temperature under magnetic stirring at -2.4 V. When TLC analysis indicated complete electrolysis of the starting material, the reaction mixture was poured into diethyl ether (30 mL), washed twice with water (20 mL × 2), dried over Na₂SO₄, and concentrated in vacuo. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (v:v = 50:1) as the eluent to afford 32.8 mg of a colorless oily liquid in a 63% yield. 1 HNMR (500MHz, CDCl3) δ8.72(dt,J=6.5,2.0Hz,1H),7.87(td,J=7.8,1.7Hz,1H),7.71(dt,J=7.7,1.2Hz,1H),7.55(ddd,J=7.8,4.8,1.3Hz,1H); 13 C NMR (126MHz, CDCl3) δ151.2, 137.1, 133.9, 128.6, 127.0, 117.2.

[0079] The embodiments described above are only preferred embodiments of the present invention and are only used to explain the present invention, not to limit the scope of implementation of the present invention. For those skilled in the art, it is of course possible to easily make other implementation methods by replacing or changing the technical content disclosed in this specification. Therefore, all changes and improvements made on the principles of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A method for electrocatalytically synthesizing nitrile compounds using thianthrenium salts as substrates, characterized in that: The following steps are involved: Thianthenium salt and p-toluenesulfonyl nitrile are used as substrates, the anode and cathode are both carbon electrodes, a DC regulated power supply is connected in an electrolyte and an organic solvent, the voltage of the DC regulated power supply is -1.5V to -2.5V, and the electrolysis reaction is stirred at room temperature for 6h to 8h to obtain a nitrile compound; the organic solvent is selected from one of THF, DMSO, MeOH, NMP or DMF; the electrolyte is selected from n Bu4NClO4, n One of Bu4NPF6, Et4NOTs or LiClO4; When the thianthrenium salt is selected from When , the corresponding nitrile compounds are benzonitrile, 4-bromobenzonitrile, 4-(trifluoromethyl)benzonitrile, terephthalonitrile, methyl 4-cyanobenzoate, 4-acetylbenzonitrile, 4-methoxybenzonitrile, 4-(benzyloxy)benzonitrile, [1,1'-biphenyl]-4-carbonitrile, isophthalonitrile, 3-methoxybenzonitrile, 3,4-dimethylbenzonitrile, 2-(trifluoromethyl)benzonitrile, benzo[d][1,3]dioxin-5-carbonitrile, thiophene-3-carbonitrile, and 2-pyridinecarbonitrile.

2. The method according to claim 1, characterized in that The molar ratio of the thianthrenium salt to p-toluenesulfonyl nitrile is 1:(1-5).

3. The method according to claim 1, characterized in that The molar ratio of the thianthrenium salt to the electrolyte is 1:(1-4).

4. The method according to claim 1, wherein The usage ratio of the thianthrenium salt to the organic solvent is 1 mmol: (4-12) mL.

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