A method for the electrochemical reduction of unactivated alkyl chlorides to organosilicon compounds under a non-sacrificial anode

Abstract

The application provides a method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under a non-sacrificial anode, comprising the following steps: adding unactivated alkyl chloride compounds or derivatives thereof, phenylsilane, a reducing agent, an electrolyte and an organic solvent into a single-compartment electrolysis cell, using an inert electrode as cathode material and anode material, passing a constant current between the two electrodes, reacting for 2-10 hours in a nitrogen or argon atmosphere, and monitoring the reaction; after the reaction is completed, the reaction solution is quenched by a saturated sodium thiosulfate solution, extracted by ethyl acetate, dried, filtered, and concentrated to obtain a crude product; the crude product is purified by silica gel column chromatography to obtain a target product. By using the technical scheme of the application, the oxidation reaction of anions on the anode synchronously provides charge balance and oxidation driving force of the reducing agent, silicon source activation is realized, the yield is high, the substrate universality is extremely strong, the reaction can be completed by using a common single-compartment electrolysis container, the equipment investment is low, and the operation is simple.

Description

Technical Field

[0001] This invention relates to the field of organic electrochemical synthesis technology, and in particular to a method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions. Background Technology

[0002] Organosilicon compounds have significant applications in materials science, medicinal chemistry, and organic synthesis. Alkyl chlorides are ideal precursors for silanization due to their commercial availability, wide availability, and low cost. However, the high C(sp³)-Cl bond dissociation energy of unactivated alkyl chlorides poses challenges to their activation and transformation in synthetic chemistry. This is especially true for tertiary alkyl chlorides, where significant steric hindrance and hindered reduction kinetics prevent the reporting of direct silanization methods based on electrochemical strategies. Traditional alkyl chloride activation methods, such as the Grignard reagent method and the organolithium reagent method, suffer from stringent operating conditions, low atom economy, and poor functional group tolerance.

[0003] In recent years, electrochemical synthesis, using electrons as a clean reducing agent, has offered advantages such as mild conditions, high controllability, and high atom economy, providing a new approach for the activation and transformation of alkyl chlorides. Existing methods for the electrochemical reduction of alkyl chlorides mainly rely on sacrificial anode strategies, using metals such as magnesium and zinc as anodes, providing electrons through metal oxidation and dissolution. While this strategy provides a continuous electron supply, it has certain limitations: continuous consumption of the anode metal leads to high costs; metal ion contamination of the products makes purification difficult; and metal salt waste is environmentally unfriendly. Recently, non-sacrificial anode strategies have been reported in the electroreduction of deuterated unactivated alkyl chlorides. This system compensates for the charge consumed during the cathode reduction process through the oxidation half-reaction of amine sacrificial reagents at the inert anode interface. However, the reduction of alkyl chlorides in this deuteration system is highly dependent on the strong negative reduction potential provided by the lead cathode to meet the reduction and activation requirements of the C(sp³)-Cl bond. However, this strategy for activating unactivated alkyl chlorides still faces technical challenges: the C(sp³)-Cl bond reduction potential is low (typically below -2.5 V vs. SCE), requiring stringent cathode conditions; the matching non-sacrificial anode oxidation kinetics are slow, and the current efficiency needs improvement. Furthermore, no silanization reactions for unactivated alkyl chlorides have been reported in non-sacrificial anode electrochemical reduction systems to date.

[0004] Therefore, there is an urgent need for an electrochemical reduction silylation method based on a non-sacrificial anode strategy, applicable to 1°, 2°, and 3° non-activated alkyl chlorides, to reduce dependence on strong reducing agents, transition metal catalysts, and sacrificial anodes, simplify the reaction apparatus, reduce reaction costs, broaden the substrate applicability range, and provide a new route for the green synthesis of organosilicon compounds. Summary of the Invention

[0005] To address the above technical problems, this invention discloses a method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions. This method eliminates the need for metal sacrificial anodes, separate electrolytic cells, and transition metal catalysts. It achieves efficient silanization of unactivated (primary / secondary / tertiary) alkyl chlorides at room temperature and constant current. Moreover, it is green, clean, and easy to scale up, solving the problems of sacrificial anode metal consumption, heavy metal pollution, complex equipment, difficulty in tertiary alkyl chloride conversion, and narrow substrate applicability in existing silanization synthesis processes.

[0006] The technical solution adopted by this invention is as follows:

[0007] A method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions includes the following steps:

[0008] Step S1: Add unactivated alkyl chloride compounds or their derivatives, benzenesilane, reducing agent, electrolyte and ultra-dry organic solvent to a single-chamber electrolytic cell without partitions. Both the cathode and anode are inert electrodes. A constant current is passed between the two electrodes. The reaction is carried out in a nitrogen or argon atmosphere for 2-10 hours, and the reaction is monitored.

[0009] In step S2, after the reaction is complete, the reaction solution is quenched with saturated sodium thiosulfate solution, extracted with ethyl acetate, the organic phases are combined, dried, filtered, and the filtrate is concentrated to obtain the crude product; the crude product is purified by silica gel column chromatography to obtain the target alkylphenylsilane product.

[0010] This technical solution uses clean electrons as redox reagents and achieves charge balance by utilizing the oxidation reaction of the reducing agent at the anode, thus avoiding the dissolution and consumption of the anode metal. The reaction conditions are mild, clean, and green, solving the problems of high reaction cost, significant pollution, and high metal residue in products in traditional electrochemical synthesis, and providing a new approach for the activation of carbon-chlorine bonds.

[0011] The above-mentioned technical solution differs fundamentally from existing non-sacrificial anode electroreduction of alkyl chloride deuteration technology in its reaction system (electrode configuration, solvent electrolyte) and charge compensation mechanism. The technical solution of this invention uses a non-separated electrolytic cell as the electrolytic device, with both the anode and cathode materials being graphite-based non-metallic inert electrodes. A reducing agent is introduced into the reaction system as a reaction medium. The oxidation reaction of the anode anion balances the charge consumption at the cathode, replacing the charge balance mode of existing deuteration systems that rely on amine sacrificial reagents for oxidation. Simultaneously, it eliminates the need for the highly reactive lead cathode required in deuteration systems, constructing a novel non-sacrificial anode electrochemical silanization method. Ultimately, the reduction and silanization of alkyl chlorides is achieved at the graphite cathode to obtain the target alkylsilane product.

[0012] Taking iodides as an example, the electrochemical reaction process of the present invention is as follows: At the cathode, unactivated alkyl chloride undergoes continuous single-electron reduction to generate alkyl anions; at the anode, iodide ions undergo oxidation to generate elemental iodine, which then complexes with iodide ions to form triiodide anions; these triiodide anions further react with benzylsilanes to generate iodobenzenesilane intermediates, which then undergo a nucleophilic reaction with the alkyl anions generated at the cathode to obtain the target silanized product. The reaction principle for other reducing agents is similar.

[0013] As a further improvement of the present invention, the molecular structure of the unactivated alkyl chloride compound or its derivative is shown in formula (1).

[0014] (1),

[0015] Among them, R1, R2, and R3 are respectively methyl, ethyl, propyl, butyl, isopropyl, cyclohexyl, phenyl, benzyl, or ether.

[0016] As a further improvement of the present invention, the unactivated alkyl chloride compound or its derivative comprises at least one of primary chloroalkanes, secondary chloroalkanes, tertiary chloroalkanes, natural products, and drug-derived chloro compounds. The primary chloroalkanes include at least one of 1-chlorooctane, 1-chloropentane, 1-chlorohexane, 1-chlorooctane, and 1-chlorodecane. The secondary chloroalkanes include at least one of chlorocyclohexane, 2-chlorobutane, and 1-chloro-1-phenylethane. The tertiary chloroalkanes include at least one of 2-chloro-2-methylpropane, 2-chloro-2-methylbutane, 2-chloro-2,4-dimethylpentane, and 2-chloro-2-phenylpropane. The natural products and drug-derived chloro compounds include at least one of chlorocholesterol and terpene chloro compounds.

[0017] As a further improvement of the present invention, the inert electrode is a graphite electrode, a glassy carbon electrode, a carbon felt electrode, a carbon paper electrode, a carbon cloth electrode, a platinum electrode, or a gold electrode.

[0018] As a further improvement of the present invention, the reducing agent is at least one selected from Et3N, NH4I, LiI, NaI, MaI2, SmI2, NH4Br, NaBr, and KBr. Further, the reducing agent is LiI, NaI, MaI2, or SmI2.

[0019] As a further improvement of the present invention, the electrolyte is at least one of LiCl, CF3LiSO3, LiTFSI, (nBu)4NI, (nBu)4NBr, (nBu)4NBF4, (nBu)4NPF6, (nBu)4NCIO4, (nBu)4NHSO4, (nBu)4NOAc, Et4NOTs, Et4NOTf, and Et4NBF4.

[0020] As a further improvement of the present invention, the solvent is at least one selected from acetonitrile, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, 1,4-dioxane, diethyl ether, methanol, ethanol, isopropanol, ethyl acetate, dichloromethane, 1,2-dichloroethane, toluene, and n-hexane.

[0021] As a further improvement of the present invention, the constant current is 1 mA to 100 mA. Further, the constant current is 5 mA to 50 mA.

[0022] As a further improvement of the present invention, thin-layer chromatography or gas chromatography-mass spectrometry is used to monitor the reaction.

[0023] As a further improvement of the present invention, the molar ratio of the unactivated alkyl chloride compound or its derivative to benzylsilane is 1:1 to 1:5. Further, the molar ratio of the unactivated alkyl chloride compound or its derivative to benzylsilane is 1:3 to 1:4. Using this technical solution, the product yield is higher.

[0024] As a further improvement of the present invention, the amount of reducing agent used is 0.5-3 molar equivalents, based on the molar number of unactivated alkyl chloride compounds. Further, the amount of reducing agent used is 2-3 molar equivalents. Using this technical solution, the product yield is higher.

[0025] As a further improvement of the present invention, the initial concentration of the electrolyte in the electrolytic cell is 0.1~1 mol / L. More specifically, the initial concentration of the electrolyte in the electrolytic cell is 0.1~0.5 mol / L.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The technical solution of this invention utilizes the oxidation reaction of anions at the anode to simultaneously provide charge balance and the driving force for the oxidation of the reducing agent, thereby activating the silicon source. A stable electrode system using inert graphite / platinum electrodes is employed, eliminating the need for lead cathodes and transition metal catalysis, resulting in high yield. It exhibits extremely broad substrate versatility, enabling the electrochemical silanization of primary, secondary, and tertiary unactivated alkyl chlorides. It is compatible with sensitive functional groups such as esters, heterocycles, alkenes, and natural products, demonstrating excellent functional group tolerance. The electrolysis process involves no metal dissolution, and the products contain no magnesium or zinc ion residues, eliminating the need for acid washing to remove metal salts, reducing purification costs, and resulting in no heavy metal solid waste emissions. It abandons the traditional H-type dual-chamber electrolytic cell and high-valence Nafion proton exchange membrane; a common single-chamber electrolytic vessel can complete the reaction, eliminating the need for a split electrolytic cell, resulting in low equipment investment and simple operation.

[0028] In addition, the technical solution of the present invention is a room temperature and atmospheric pressure reaction, with electrons as a clean redox medium, producing only a small amount of iodized salt wastewater that can be reduced and recovered. The reaction system can be directly scaled up to the gram scale, making it suitable for industrial pilot production. The reaction is green, mild, and easy to scale up. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the reaction equation for step (1) of the method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chloride under non-sacrificial anode according to the present invention.

[0030] Figure 2 This is a schematic diagram of the reaction equation for Embodiment 1 of the present invention.

[0031] Figure 3 This is the hydrogen NMR spectrum of the product obtained in Example 1 of the present invention.

[0032] Figure 4 This is the carbon NMR spectrum of the product obtained in Example 1 of the present invention.

[0033] Figure 5 This is the hydrogen NMR spectrum of the product obtained in Example 2 of the present invention.

[0034] Figure 6 This is the carbon NMR spectrum of the product obtained in Example 2 of the present invention.

[0035] Figure 7 This is the hydrogen NMR spectrum of the product obtained in Example 3 of the present invention.

[0036] Figure 8 This is the carbon NMR spectrum of the product obtained in Example 3 of the present invention.

[0037] Figure 9 This is the hydrogen NMR spectrum of the product obtained in Example 4 of the present invention.

[0038] Figure 10 This is the carbon NMR spectrum of the product obtained in Example 4 of the present invention.

[0039] Figure 11 This is the hydrogen NMR spectrum of the product obtained in Example 5 of the present invention.

[0040] Figure 12 This is the carbon NMR spectrum of the product obtained in Example 5 of the present invention. Detailed Implementation

[0041] The preferred embodiments of the present invention will be described in further detail below.

[0042] A method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions includes the following steps:

[0043] (1) In a clean electrolytic cell equipped with a magnetic stir bar, add unactivated alkyl chloride compounds or their derivatives, benzyl silane, sodium iodide, and lithium bis(trifluoromethanesulfonyl)imide, then add solvent. Use inert electrodes as cathode and anode materials, and pass a constant current between the two electrodes. React for 2-10 hours in a nitrogen or argon atmosphere at a certain temperature, and monitor the reaction using thin-layer chromatography. The constant current is 1 mA to 100 mA. The inert electrode is a graphite electrode, glassy carbon electrode, carbon felt electrode, carbon paper electrode, carbon cloth electrode, platinum electrode, gold electrode, etc.

[0044] The above reaction equation is as follows Figure 1 As shown in the figure, PhSiH3 is a silicon-derived benzenesilane, and R1, R2, and R3 are respectively methyl, ethyl, propyl, butyl, isopropyl, cyclohexyl, phenyl, benzyl, or ether group, etc.

[0045] The unactivated alkyl chloride compound or its derivative is selected from one of the following substrates:

[0046] Primary chloroalkanes: 1-chlorooctane, 1-chloropentane, 1-chlorohexane, 1-chlorooctane, 1-chlorodecane, etc.;

[0047] Secondary chloroalkanes: chlorocyclohexane, 2-chlorobutane, 1-chloro-1-phenylethane, etc.;

[0048] Tertiary chloroalkanes: 2-chloro-2-methylpropane, 2-chloro-2-methylbutane, 2-chloro-2,4-dimethylpentane, 2-chloro-2-phenylpropane, etc.;

[0049] Chlorinated derivatives of natural products and pharmaceuticals: chlorinated cholesterol, chlorinated terpenes.

[0050] The reducing agent is selected from any one or more of Et3N, NH4I, LiI, NaI, MaI2, SmI2, NH4Br, NaBr, and KBr.

[0051] The electrolyte is selected from any one or more of LiCl, CF3LiSO3, LiTFSI, (nBu)4NI, (nBu)4NBr, (nBu)4NBF4, (nBu)4NPF6, (nBu)4NCIO4, (nBu)4NHSO4, (nBu)4NOAc, Et4NOTs, Et4NOTf, and Et4NBF4.

[0052] The solvent is one or a mixture of acetonitrile, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, 1,4-dioxane, diethyl ether, methanol, ethanol, isopropanol, ethyl acetate, dichloromethane, 1,2-dichloroethane, toluene, and n-hexane.

[0053] The molar ratio of the unactivated alkyl chloride compound or its derivative to benzylsilane is 1:1 to 1:5.

[0054] The amount of reducing agent required is 0.5-3 molar equivalents, based on the molar number of unactivated alkyl chloride compounds.

[0055] (2) After the reaction is completed, the reaction solution is quenched with saturated sodium thiosulfate solution to remove excess iodine, extracted with ethyl acetate, the organic phases are combined, dried with anhydrous sodium sulfate, filtered, and the filtrate is concentrated to obtain the crude product. The crude product is purified by silica gel column chromatography to obtain the silanized product.

[0056] The technical solution of this invention has mild reaction conditions, low cost, wide availability of raw materials, and simple operation. It can be applied to a wide range of unactivated alkyl chloride compounds (including primary chloroalkanes, secondary chloroalkanes, and tertiary chloroalkanes), and also has a highly efficient selective silanization effect in derivatives of multiple chloroalkanes. At the same time, it is suitable for gram-scale reactions.

[0057] The following description uses specific examples to illustrate the point.

[0058] Example 1 Under a nitrogen atmosphere, 1-chlorooctane (1 mmol), phenylsilane (3.5 mmol), sodium iodide (3 mmol), lithium bis(trifluoromethanesulfonyl)imide, and 5 mL of ultra-dry tetrahydrofuran were added to an electrolytic cell. The concentration of lithium bis(trifluoromethanesulfonyl)imide was 0.2 M. Graphite electrodes were fixed on both sides as the cathode and anode. The reaction was carried out under a constant current of 15 mA at room temperature in a nitrogen atmosphere. The reaction equation is as follows. Figure 2 As shown, 1a is 1-chlorooctane and 2a is n-octylphenylsilane.

[0059] After the reaction was complete, the reaction solution was quenched with saturated sodium thiosulfate solution, extracted with ethyl acetate (3 × 10 mL), the organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated. Then, using petroleum ether as eluent, the product was purified by silica gel column chromatography to obtain a colorless liquid product (n-octylphenylsilane), with the structure shown below. Figure 2 As shown in 2a on the right-hand side of the reaction equation, the yield was 62.2 mg, with a yield of 94%.

[0060] The product was tested, and the results are as follows:

[0061] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.61 – 7.52 (m, 2H), 7.42– 7.30 (m, 3H), 4.27 (t, J = 3.5 Hz, 2H), 1.44 (p, J = 7.5 Hz, 2H), 1.34 (t,J = 7.3 Hz, 2H), 1.30 – 1.17 (m, 7H), 0.97 – 0.83 (m, 6H); see Figure 3 .

[0062] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 135.32, 132.94, 129.57, 128.05, 32.96, 31.99, 29.33, 29.31, 25.18, 22.78, 14.21, 10.11; see details Figure 4 .

[0063] Example 2

[0064] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane is replaced with an equimolar amount of the compound shown in formula (2). Petroleum ether is used as the eluent to obtain a colorless liquid product 2b, the structure of which is shown in formula (3) below, with a yield of 53.1 mg and a yield of 93%.

[0065] (2)

[0066] (3)

[0067] The product was tested, and the results are as follows:

[0068] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.57 (dd, J = 7.8, 1.7Hz, 2H), 7.44 – 7.31 (m, 3H), 5.79 (ddt, J = 17.0, 10.4, 6.8 Hz, 1H), 5.04 –4.89 (m, 2H), 4.29 (t, J = 3.6 Hz, 2H), 2.05 (q, J = 5.6, 5.2 Hz, 2H), 1.47(t, J = 3.8 Hz, 4H), 0.98 – 0.92 (m, 2H); see Figure 5 .

[0069] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 138.96, 135.31, 132.78, 129.62, 128.08, 114.45, 33.51, 32.13, 24.68, 9.98; see details Figure 6 .

[0070] Example 3

[0071] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane is replaced with an equimolar amount of the compound shown in formula (4). Petroleum ether is used as the eluent to obtain a colorless liquid product 2c, the structure of which is shown in formula (5) below, with a yield of 46.6 mg and a yield of 70%.

[0072] (4)

[0073] (5)

[0074] The product was tested, and the results are as follows:

[0075] The 1H NMR spectrum is as follows: 1 ¹H NMR (500 MHz, Chloroform-d) δ 7.62 – 7.54 (m, 2H), 7.44– 7.33 (m, 3H), 4.31 (t, J = 3.8 Hz, 2H), 1.62 – 1.50 (m, 2H), 1.07 – 0.99 (m, 2H), 0.70 – 0.60 (m, 1H), -0.01 (s, 9H); see details Figure 7 .

[0076] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 135.31, 132.89, 129.55, 128.05, 29.80, 20.56, 19.81, 14.40, -1.55; see details Figure 8 .

[0077] Example 4

[0078] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (6). Petroleum ether was used as the eluent to obtain a colorless liquid product 2d, the structure of which is shown in formula (7) below, with a yield of 47.0 mg and a yield of 61%.

[0079] (6)

[0080] (7)

[0081] The product was tested, and the results are as follows:

[0082] The 1H NMR spectrum is as follows: 1 ¹H NMR (500 MHz, Chloroform-d) δ 7.56 – 7.49 (m, 4H), 7.42– 7.28 (m, 6H), 4.40 – 4.31 (m, 2H), 0.37 – 0.33 (m, 2H), 0.32 (d, J = 2.4Hz, 6H); see details. Figure 9 .

[0083] The carbon NMR spectrum is as follows: 3 C NMR (126 MHz, Chloroform-d) δ 139.99, 135.00, 134.00, 133.46, 129.56, 129.04, 128.04, 127.86, -1.11, -4.65; see details Figure 10 .

[0084] Example 5

[0085] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (8). Petroleum ether was used as the eluent to obtain a colorless liquid product 2e, the structure of which is shown in formula (9), with a yield of 60.4 mg and a yield of 89%.

[0086] (8)

[0087] (9)

[0088] The product was tested, and the results are as follows:

[0089] The 1H NMR spectrum is as follows: 1¹H NMR (500 MHz, Chloroform-d) δ 7.57 – 7.53 (m, 2H), 7.44– 7.33 (m, 3H), 7.31 – 7.24 (m, 2H), 7.21 – 7.13 (m, 3H), 4.30 (t, J = 3.7 Hz, 2H), 2.67 (t, J = 7.6 Hz, 2H), 1.96 – 1.66 (m, 2H), 1.06 – 0.93 (m, 2H); see details. Figure 11 .

[0090] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 142.22, 135.33, 132.54, 129.67, 128.62, 128.38, 128.10, 125.87, 39.07, 27.10, 9.86; see details Figure 12 .

[0091] Example 6

[0092] All other steps in this embodiment are the same as in Example 1, except that in Example 1, 1-chlorooctane is replaced with an equimolar amount of the compound shown in formula (10). The eluent is petroleum ether / ethyl acetate (V... PE :V EA = 100:1), to obtain colorless liquid product 2f, the structure of which is shown in formula (11), with a yield of 51.4 mg and a yield of 57%.

[0093] (10)

[0094] (11)

[0095] The product was tested, and the results are as follows:

[0096] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.58 – 7.53 (m, 2H), 7.41– 7.31 (m, 3H), 6.68 (d, J = 8.5 Hz, 1H), 6.46 (d, J = 2.5 Hz, 1H), 6.29 (dd,J = 8.4, 2.5 Hz, 1H), 5.89 (s, 2H), 4.30 (t, J = 3.7 Hz, 2H), 3.86 (t, J =6.4 Hz, 2H), 1.86 – 1.76 (m, 2H), 1.61 (p, J = 7.8 Hz, 2H), 1.04 – 0.95 (m,2H);

[0097] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 154.69, 148.29, 141.56,135.32, 132.47, 129.70, 128.11, 108.01, 105.72, 101.16, 98.14, 68.44, 32.37,21.73,9.91.

[0098] Example 7

[0099] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (12). Petroleum ether was used as the eluent to obtain 2 g of colorless liquid product with the structure shown in formula (13) below, yielding 63.8 mg and a yield of 65%.

[0100] (12)

[0101] (13)

[0102] The product was tested, and the results are as follows:

[0103] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 8.11 (d, J = 7.7 Hz, 2H),7.54 – 7.50 (m, 2H), 7.49 – 7.44 (m, 2H), 7.42 – 7.32 (m, 5H), 7.27 – 7.20(m, 2H), 4.34 – 4.25 (m, 4H), 1.95 (p, J = 7.4 Hz, 2H), 1.64 – 1.54 (m, 2H), 1.04 – 0.93 (m, 2H).

[0104] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 140.47, 135.31, 132.26,129.76, 128.15, 125.71, 122.94, 120.47, 118.86, 108.71, 42.78, 32.00, 23.01,10.04.

[0105] Example 8

[0106] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (14). Petroleum ether was used as the eluent to obtain a colorless liquid product for 2 hours, the structure of which is shown in formula (15) below, with a yield of 48.4 mg and a yield of 74%.

[0107] (14)

[0108] (15)

[0109] The product was tested, and the results are as follows:

[0110] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.61 – 7.52 (m, 2H), 7.45– 7.32 (m, 3H), 7.10 (d, J = 5.6 Hz, 1H), 6.92 – 6.85 (m, 1H), 6.78 (d, J =3.4 Hz, 1H), 4.32 (t, J = 3.6 Hz, 2H), 3.02 – 2.95 (m, 2H), 1.43 – 1.34 (m, 2H);

[0111] The carbon NMR spectrum is as follows: 13C NMR (126 MHz, Chloroform-d) δ 147.40, 135.36, 131.90, 129.84, 128.19, 126.78, 123.73, 123.06, 25.52, 12.85.

[0112] Example 9

[0113] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (16). Petroleum ether is used as the eluent. Only the type of reducing agent is changed; the remaining electrochemical parameters, solvent, electrolyte, reaction temperature, and charge are completely unchanged. The separation yields of the colorless liquid product 2i corresponding to different reducing agents are as follows:

[0114] The reducing agent was NH4Br, and the yield of product 2i was 26.7 mg, with a yield of 52%.

[0115] The reducing agent was KBr, and the yield of product 2i was 28.0 mg, with a yield of 49%.

[0116] The reducing agent was KI, and the yield of product 2i was 24.0 mg, with a yield of 42%.

[0117] The reducing agent was NaI, and the yield of product 2i was 50.8 mg, with a yield of 89%.

[0118] (16)

[0119] (17)

[0120] The product obtained using NH4Br as the reducing agent was tested, and the results are as follows:

[0121] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.55 (d, J = 6.9 Hz, 2H), 7.43 – 7.31 (m, 3H), 4.16 (d, J = 2.9 Hz, 2H), 1.98 – 1.59 (m, 5H), 1.25 (d,J = 5.1 Hz, 5H), 1.14 – 1.05 (m, 1H).

[0122] The carbon NMR spectrum is as follows: 13C NMR (126 MHz, Chloroform-d) δ 135.72, 132.22, 129.55,127.98, 28.93, 27.74, 26.70, 22.22.

[0123] The products obtained using other reducing agents, KBr, KI, and NaI, were tested, and the resulting products... 1 H NMR, 13 The C NMR chemical shift, peak shape, integration ratio, and coupling constant are consistent with the above spectral data.

[0124] Example 10

[0125] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (18). The eluent used was petroleum ether / ethyl acetate (VPE:VEA = 50:1), yielding a colorless liquid product 2j with the structure shown in formula (19) below, with a yield of 35.8 mg and a yield of 62%.

[0126] (18)

[0127] (19)

[0128] The product was tested, and the results are as follows:

[0129] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.58 – 7.53 (m, 2H), 7.43– 7.33 (m, 3H), 4.21 (d, J = 3.0 Hz, 2H), 4.04 – 3.89 (m, 2H), 3.47 – 3.32(m, 2H), 1.66 – 1.59 (m, 4H), 1.36 – 1.28 (m, 1H);

[0130] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 135.69, 131.00, 129.89,128.15, 69.20, 28.46, 19.19.

[0131] Example 11

[0132] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (20). The eluent used was petroleum ether / ethyl acetate (VPE:VEA = 50:1), yielding a colorless liquid product 2k with the structure shown in formula (21) below, with a yield of 120.8 mg and a yield of 94%.

[0133] (20)

[0134] (twenty one)

[0135] The product was tested, and the results are as follows:

[0136] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.67 (d, J = 7.9 Hz, 1H), 7.63 – 7.56 (m, 2H), 7.45 – 7.33 (m, 4H), 7.27 – 7.21 (m, 1H), 7.18 – 7.12(m, 2H), 7.12 – 7.03 (m, 2H), 6.83 – 6.77 (m, 2H), 6.56 – 6.50 (m, 1H), 4.33– 4.25 (m, 2H), 4.22 (t, J = 7.0 Hz, 2H), 3.98 – 3.91 (m, 2H), 2.79 – 2.54(m, 2H), 2.12 – 2.02 (m, 2H), 1.88 – 1.75 (m, 3H), 1.68 – 1.58 (m, 1H), 1.24– 1.18 (m, 1H), 1.15 (d, J = 6.9 Hz, 3H);

[0137] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 157.12, 136.08, 135.78,134.75, 132.03, 129.70, 129.41, 128.75, 128.09, 127.89, 121.54, 121.12,119.38, 114.45, 109.49, 101.21, 67.48, 46.20, 35.66, 33.92, 27.27, 26.89,16.13, 15.91.

[0138] Example 12

[0139] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (22). Petroleum ether was used as the eluent to obtain 2l of colorless liquid product with the structure shown in formula (23) below, with a yield of 66.4 mg and a yield of 87%.

[0140] (twenty two)

[0141] (twenty three)

[0142] The product was tested, and the results are as follows:

[0143] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.63 – 7.58 (m, 2H), 7.46– 7.34 (m, 3H), 7.25 (t, J = 7.5 Hz, 2H), 7.20 – 7.10 (m, 3H), 4.24 (s, 2H),2.88 – 2.42 (m, 2H), 1.69 – 1.59 (m, 2H), 1.09 (s, 6H);

[0144] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 143.20, 136.12, 131.94, 129.76, 128.43, 128.39, 128.03, 125.74, 43.32, 31.68, 25.21, 20.52.

[0145] Example 13

[0146] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (24). Petroleum ether was used as the eluent to obtain a colorless liquid product 2m, the structure of which is shown in formula (25) below, with a yield of 61.9 mg and a yield of 80%.

[0147] (twenty four)

[0148] (25)

[0149] The product was tested, and the results are as follows:

[0150] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.59 – 7.51 (m, 2H), 7.44– 7.39 (m, 1H), 7.38 – 7.34 (m, 2H), 7.04 (dd, J = 8.5, 5.6 Hz, 2H), 6.93 (t,J = 8.7 Hz, 2H), 4.16 (s, 2H), 2.65 (s, 2H), 0.97 (s, 6H);

[0151] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 161.64 (d, J = 243.7 Hz),136.21, 133.78 (d, J = 3.3 Hz), 131.90 (d, J = 7.7 Hz), 131.64, 129.80,128.01, 114.54 (d, J = 21.0 Hz), 45.15, 24.25, 21.16.

[0152] Example 14

[0153] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (26). Petroleum ether was used as the eluent to obtain a colorless liquid product 2n, the structure of which is shown in formula (27) below, with a yield of 75.2 mg and a yield of 84%.

[0154] (26)

[0155] (27)

[0156] The product was tested, and the results are as follows:

[0157] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.68 – 7.58 (m, 2H), 7.49– 7.33 (m, 3H), 6.72 (d, J = 7.8 Hz, 1H), 6.65 – 6.56 (m, 2H), 5.91 (s, 2H), 4.25 (s, 2H), 2.85 – 2.34 (m, 2H), 1.93 – 1.38 (m, 2H), 1.10 (s, 6H);

[0158] The carbon NMR spectrum is as follows: 13C NMR (126 MHz, Chloroform-d) δ 147.60, 145.56, 137.05,136.11, 131.91, 129.79, 128.05, 120.99, 108.90, 108.23, 100.82, 43.61, 31.45,25.23, 20.47.

[0159] Example 15

[0160] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (28). Petroleum ether was used as the eluent to obtain a colorless liquid product 2o, the structure of which is shown in formula (29) below, with a yield of 67.9 mg and a yield of 93%.

[0161] (28)

[0162] (29)

[0163] The product was tested, and the results are as follows:

[0164] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.57 – 7.51 (m, 2H), 7.42– 7.32 (m, 3H), 3.99 (s, 2H), 1.85 (s, 3H), 1.81 – 1.69 (m, 12H);

[0165] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 136.18, 131.39, 129.56, 127.85, 38.70, 37.29, 27.76, 21.43.

[0166] Example 16

[0167] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (30). Petroleum ether was used as the eluent to obtain a colorless liquid product 2p, the structure of which is shown in formula (31) below, with a yield of 63.6 mg and a yield of 75%.

[0168] (30)

[0169] (31)

[0170] The product was tested, and the results are as follows:

[0171] The 1H NMR spectrum is as follows: 1 H NMR (500 MHz, Chloroform-d) δ 7.67 – 7.61 (m, 2H), 7.43– 7.34 (m, 3H), 7.31 – 7.23 (m, 2H), 7.20 – 7.15 (m, 1H), 7.13 (d, J = 6.8Hz, 2H), 4.30 (s, 2H), 2.70 – 2.50 (m, 2H), 1.78 – 1.65 (m, 2H), 1.56 (d, J =7.5 Hz, 4H), 0.96 (t, J = 7.5 Hz, 6H);

[0172] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 143.36, 136.20, 132.25,129.62, 128.43, 128.35, 128.02, 125.74, 37.41, 30.86, 28.61, 27.41, 8.80.

[0173] Example 17

[0174] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane in Example 1 is replaced with an equimolar amount of the compound shown in formula (32). The eluent used was petroleum ether / ethyl acetate (VPE:VEA = 50:1), yielding a colorless liquid product 2q with the structure shown in formula (33) below, with a yield of 82.8 mg and a yield of 73%.

[0175] (32)

[0176] (33)

[0177] The product was tested, and the results are as follows:

[0178] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.54 (dd, J = 7.8, 1.6Hz, 2H), 7.43 – 7.29 (m, 3H), 5.83 (d, J = 3.7 Hz, 1H), 4.48 (d, J = 3.7 Hz, 1H), 4.31 – 4.23 (m, 3H), 4.09 (dd, J = 7.6, 3.1 Hz, 1H), 4.09 – 4.00 (m,1H), 4.01 – 3.92 (m, 1H), 3.82 (d, J = 3.1 Hz, 1H), 3.64 – 3.55 (m, 1H), 3.50(td, J = 6.2, 3.2 Hz, 1H), 1.68 – 1.58 (m, 2H), 1.52 (d, J = 7.6 Hz, 2H), 1.48 (s, 3H), 1.40 (s, 3H), 1.31 (d, J = 8.2 Hz, 2H), 0.97 – 0.91 (m, 6H);

[0179] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 135.27, 132.50, 129.69,128.10, 111.81, 108.99, 105.35, 82.61, 82.19, 81.29, 72.57, 70.17, 67.32,32.77, 26.93, 26.87, 26.34, 25.47, 21.71, 9.85.

[0180] Example 18

[0181] All other steps in this embodiment are the same as in Example 1, except that 1-chlorooctane is replaced with an equimolar amount of the compound shown in formula (34). Petroleum ether is used as the eluent to obtain a colorless liquid product 2r, the structure of which is shown in formula (35) below, with a yield of 137.4 mg and a yield of 96%.

[0182] (34)

[0183] (35)

[0184] Its parameters, after testing, are as follows:

[0185] The 1H NMR spectrum is as follows: 1H NMR (500 MHz, Chloroform-d) δ 7.59 – 7.53 (m, 2H), 7.43– 7.32 (m, 3H), 5.33 – 5.21 (m, 1H), 4.20 (d, J = 3.0 Hz, 2H), 2.31 – 1.80(m, 6H), 1.77 – 1.23 (m, 15H), 1.21 – 1.06 (m, 6H), 1.04 – 1.02 (m, 2H), 0.97 (s, 3H), 0.94 – 0.91 (m, 3H), 0.90 – 0.86 (m, 6H), 0.68 (s, 2H);

[0186] The carbon NMR spectrum is as follows: 13 C NMR (126 MHz, Chloroform-d) δ 143.54, 135.70, 131.84,129.63, 128.03, 119.07, 56.92, 56.24, 50.71, 42.37, 41.34, 39.90, 39.61,37.39, 36.28, 35.89, 34.89, 31.93, 31.87, 28.33, 28.11, 25.01, 24.35, 23.91,23.79, 22.92, 22.66, 20.81, 19.48, 18.81, 11.96.

[0187] Comparative Example 1 (Sacrificial Anode):

[0188] Based on Example 1, the difference in this comparative example is that the anode was replaced with a magnesium sheet (sacrificial anode). After the reaction, the magnesium sheet dissolved significantly, producing a large amount of white precipitate. Post-treatment required additional acid washing to remove magnesium ions. The product obtained was n-octylphenylsilane, with a yield of 39.7 mg and a yield of 61%.

[0189] Comparative Example 2 (Segmented Electrolytic Cell):

[0190] Based on Example 1, this comparative example differs in that an H-type segmented electrolytic cell is used, with the cathode and anode chambers separated by a Nafion 117 proton exchange membrane. The anolyte is a tetrabutylammonium iodide acetonitrile solution, and the cathode electrolyte is a reaction mixture. After the reaction, no silicon-based products are generated.

[0191] Comparative Example 3 (without benzenesilane):

[0192] The difference in this comparative example compared to Example 1 is that no benzylsilane was added. After the reaction was completed, only a small amount of coupling byproducts were detected, and no silylation products were generated.

[0193] In summary, compared with the prior art, the present invention has the following features and advantages:

[0194] (1) Using inexpensive sodium iodide as a reducing agent, its iodide anions undergo oxidation at the anode, simultaneously providing charge balance and driving force for the oxidation of the reducing agent.

[0195] (2) Non-sacrificial anode strategy: Inert graphite / platinum electrodes form a stable electrode system, avoiding the metal dissolution and consumption of traditional sacrificial anodes.

[0196] (3) Single-chamber operation: The undivided electrolytic cell simplifies the device and eliminates the need for expensive proton exchange membranes and complex dual-chamber designs.

[0197] (4) The method provided by this invention breaks through the dependence of traditional silanization on strong reducing agents, transition metal catalysts and segmented electrolytic cells, and realizes efficient silanization of unactivated alkyl chlorides, providing a new route for the synthesis of organosilicon compounds.

[0198] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions, characterized in that: Includes the following steps: Step S1: Add unactivated alkyl chloride compounds or their derivatives, benzenesilane, reducing agent, electrolyte, and ultra-dry organic solvent to a single-chamber electrolytic cell without partitions. Both the cathode and anode are inert electrodes, and a constant current is passed between the two electrodes. The reaction is carried out in a nitrogen or argon atmosphere for 2-10 hours, and the reaction is monitored. The reducing agent is at least one of NH4Br, KBr, KI, and Na1. The molecular structure of the unactivated alkyl chloride compounds or their derivatives is shown in formula (1). （1）， Among them, R1, R2, and R3 are respectively methyl, ethyl, propyl, butyl, isopropyl, cyclohexyl, phenyl, and benzyl; The reaction formula for step S1 is shown below: ； In step S2, after the reaction is complete, the reaction solution is quenched with saturated sodium thiosulfate solution, extracted with ethyl acetate, the organic phases are combined, dried, filtered, and the filtrate is concentrated to obtain the crude product; the crude product is purified by silica gel column chromatography to obtain the target alkylphenylsilane product.

2. A method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode conditions, characterized in that: Includes the following steps: Step S1: Add unactivated alkyl chloride compounds or their derivatives, benzenesilane, reducing agent, electrolyte and ultra-dry organic solvent to a single-chamber electrolytic cell without partitions. Both the cathode and anode are inert electrodes. A constant current is passed between the two electrodes. The reaction is carried out in a nitrogen or argon atmosphere for 2-10 hours, and the reaction is monitored. The reducing agent is at least one of NH4Br, KBr, KI and Na1. The unactivated alkyl chloride compound or its derivative is selected from at least one of primary chloroalkanes, secondary chloroalkanes, tertiary chloroalkanes, natural products and drug-derived chloro compounds; the primary chloroalkanes are selected from at least one of 1-chlorooctane, 1-chloropentane, 1-chlorohexane, and 1-chlorodecane; the secondary chloroalkanes are selected from at least one of chlorocyclohexane, 2-chlorobutane, and 1-chloro-1-phenylethane; the tertiary chloroalkanes are selected from at least one of 2-chloro-2-methylpropane, 2-chloro-2-methylbutane, 2-chloro-2,4-dimethylpentane, and 2-chloro-2-phenylpropane; the natural products and drug-derived chloro compounds are selected from at least one of chlorocholesterol and terpene chloro compounds, and the terpene chloro compounds have the structural formula shown in formula (34): （34）； The reaction formula for step S1 is shown below: ； In step S2, after the reaction is complete, the reaction solution is quenched with saturated sodium thiosulfate solution, extracted with ethyl acetate, the organic phases are combined, dried, filtered, and the filtrate is concentrated to obtain the crude product; the crude product is purified by silica gel column chromatography to obtain the target alkylphenylsilane product.

3. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 1 or 2, characterized in that: The inert electrode is a graphite electrode, glassy carbon electrode, carbon felt electrode, carbon paper electrode, carbon cloth electrode, platinum electrode, or gold electrode.

4. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 1 or 2, characterized in that: The electrolyte is at least one of LiCl, CF3LiSO3, LiTFSI, (nBu)4NI, (nBu)4NBr, (nBu)4NBF4, (nBu)4NPF6, (nBu)4NClO4, (nBu)4NHSO4, (nBu)4NOAc, Et4NOTs, Et4NOTf, and Et4NBF4.

5. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 1 or 2, characterized in that: The solvent is at least one selected from acetonitrile, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, 1,4-dioxane, diethyl ether, methanol, ethanol, isopropanol, ethyl acetate, dichloromethane, 1,2-dichloroethane, toluene, and n-hexane.

6. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 1 or 2, characterized in that: The constant current is 1 mA to 100 mA; the reaction is monitored using thin-layer chromatography or gas chromatography-mass spectrometry.

7. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 1 or 2, characterized in that: The molar ratio of the unactivated alkyl chloride compound or its derivative to benzylsilane is 1:1 to 1:

5.

8. The method for preparing organosilicon compounds by electrochemical reduction of unactivated alkyl chlorides under non-sacrificial anode according to claim 7, characterized in that: Based on the molar number of unactivated alkyl chloride compounds, the amount of reducing agent used is 0.5-3 molar equivalents.

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