Method for synthesizing aminosilane through continuous flow photocatalysis

Abstract

The invention discloses a method for synthesizing aminosilane through continuous flow photocatalysis. The method comprises the following steps: mixing olefin, silane, a photocatalyst Ir [dF (CF3) ppy] 2 (dtbbpy) PF6 and oxime ester, dissolving the mixture in acetone, continuously introducing the mixed solution into a reactor through a pump, carrying out a reaction under visible light irradiation and room temperature conditions, continuously introducing a hydrochloric acid solution and the reacted solution into the reactor through a pump, and carrying out a reaction to prepare the corresponding aminosilane. The method is mild in reaction condition and good in product selectivity, the reaction time is greatly shortened, and large-scale synthesis can be carried out.

Description

Technical Field

[0001] This invention relates to a method for the continuous flow photocatalytic synthesis of aminosilanes, belonging to the field of organic synthesis chemistry technology. Background Technology

[0002] Organosilicon compounds are indispensable synthetic reagents and intermediates in modern organic synthesis. Among them, aminosilanes possess unique biological activities and are often incorporated into peptide-mimicking agents, such as angiotensin-converting enzyme (ACE) inhibitors and serine proteases, human neutrophil elastase (HNE) inhibitors. Aminosilanes can serve as effective mimics of natural amino acids in protease inhibitors, such as valine mimics, methionine mimics, leucine mimics, and lysine mimics. It has also been successfully introduced into peptide isosteres, providing a powerful tool for research in related fields (Yu, X.; Daniliuc, CG; Alasmary, FA; Studer, A. Direct Access to α-Aminosilanes Enabled by Visible-Light-Mediated Multicomponent Radical Cross-Coupling. Angew. Chem. Int. Ed. 2021, 60(43), 23335-23341).

[0003] Currently, the main methods for preparing aminosilanes include the following approaches. Reference 1 synthesized aminosilanes by adding silyl lithium reagent to activated imine. However, this method has obvious limitations. It not only requires the introduction of an activating group at the nitrogen atom of the imine, but also relies on an air-sensitive organometallic Si reagent, which greatly limits the range of substrates (Ghosh, AK; Xu, C.-X.; Kulkarni, SS; Wink, D. TiCl4-Promoted Multicomponent Reaction: A New Entry to Functionalized α-AminoAcids. Org. Lett. 2005, 7(1), 7-10). Reference 2 successfully synthesized aminosilanes using a copper catalyst, diethoxymethylsilane as a reducing agent, and O-benzoylhydroxylamine as an electrophilic nitrogen source. This highly enantiomeric and regioselective hydrogenation amination reaction is well compatible with differentially substituted vinylsilanes, providing an effective route for the preparation of amino acid mimics and other chiral organosilicon compounds with potential applications (Niljianskul, N.; Zhu, S.; Buchwald, S.L. Enantioselective Synthesis of α-Aminosilanes by Copper-Catalyzed Hydroamination of Vinylsilanes. Angew. Chem. Int. Ed. 2015, 54(5), 1638-1641). Reference 3 employs FeCl2 and di-tert-butyl peroxide (DTBP) catalyzed intermolecular 1,2-aminosilylation of olefins with silanes. Furthermore, this reaction can be extended to the three-component 1,2-carbon acylation of olefins via Si-H / CH oxidative functionalization. However, his substrate range is limited to styrene-based compounds, which is very restrictive (Yang, Y.; Song, R.-J.; Ouyang, X.-H.; et al. Iron-Catalyzed Intermolecular 1,2-Difunctionalization of Styrenes and Conjugated Alkenes with Silanes and Nucleophiles. Angew. Chem. Int. Ed. 2017, 56(27), 7916-7919). Reference 4 employs a photoredox catalytic strategy to achieve a three-component coupling reaction of (trimethylsilyl)silane with starting materials alkylamine and aldehyde, thereby synthesizing aminosilanes. Under mild reaction conditions, this method can efficiently prepare a variety of highly functionalized aminosilanes.However, the substrate scope of this method is relatively limited and it cannot react effectively with aromatic amines (Yu, X.; Daniliuc, CG; Alasmary, FA; Studer, A. Direct Access to α-Aminosilanes Enabled by Visible-Light-Mediated Multicomponent Radical Cross-Coupling. Angew. Chem. Int. Ed. 2021, 60(43), 23335-23341).

[0004] In summary, existing synthetic strategies for aminosilanes still have certain limitations in terms of substrate scope or reaction conditions. Therefore, exploring a photocatalytic route for the synthesis of aminosilanes with mild conditions and a broad substrate scope is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a mild, continuous-flow photocatalytic method for the synthesis of aminosilanes. This method involves synthesizing aminosilanes at room temperature using inexpensive olefins, oxime esters, and silanes as raw materials under visible light irradiation.

[0006] The technical solution for achieving the objective of this invention is as follows:

[0007] A continuous-flow photocatalytic synthesis method for aminosilanes, with the following general reaction formula:

[0008] Specifically, the following steps are included:

[0009] (1) An olefin, silane, photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6, and oxime ester are mixed and dissolved in acetone. The mixed solution is then continuously fed into reactor I through pump I, and reacted under visible light irradiation and room temperature conditions. The structural formula of the olefin is: The structural formula of the silane is as follows: Where R is selected from aryl or ester group, and R1, R2, and R3 are selected from aryl or alkyl group;

[0010] (2) The hydrochloric acid solution is continuously fed into reactor II via pump II to react with the solution after the reaction in step 1.

[0011] (3) After the reaction is complete, the reaction product is collected, the solvent is removed by rotary evaporation, and the product is extracted with ethyl acetate. The organic phase is dried with anhydrous sodium sulfate, and the solvent is removed by rotary evaporation. Finally, the product is purified by column chromatography to obtain the corresponding aminosilane.

[0012] Further, in step (1), the olefin is ethyl methacrylate, benzyl methacrylate, benzyl acrylate or styrene.

[0013] Further, in step (1), the silane is triethylsilane, tert-butyldimethylsilane, diphenylmethylsilane or dimethylphenylsilane.

[0014] Furthermore, in step (1), the structural formula of the oxime ester is as follows: Selected from benzophenone O-(4-methoxybenzoyl) oxime, benzophenone O-(4-methylbenzoyl) oxime, benzophenone O-(4-fluorobenzoyl) oxime, or benzophenone O-isobutyryl oxime, with the following structural formula:

[0015]

[0016] Furthermore, in step (1), the wavelength of visible light is 400–700 nm.

[0017] Furthermore, in step (1), the molar ratio of olefin, oxime ester and silane is 1:1 to 2:1 to 10.

[0018] Furthermore, in step (2), the concentration of the hydrochloric acid solution is 4–10 mol / L.

[0019] Further, in step (1) or (2), pump I or pump II is a plunger pump, gear pump, peristaltic pump or injection pump.

[0020] Furthermore, in step (1), the reaction time is 20 to 60 minutes, the flow rate of the reaction solution is 0.5 to 2 mL / min, and the volume of reactor I is 20 to 60 mL.

[0021] Further, in step (3), the column chromatography solvent is petroleum ether (PE) and ethyl acetate (EA) in a volume ratio of 2:1 to 1:2.

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

[0023] (1) This invention selects a photocatalyst and uses visible light to induce an organic reaction. Compared with traditional organic reactions, it has the advantages of mild conditions, simple operation, good functional group tolerance, and high yield.

[0024] (2) The method of the present invention is simple and can be used for large-scale synthesis through flow photochemistry, which greatly shortens the reaction time. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a continuous flow photocatalytic synthesis method for aminosilanes. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0027] Example 1

[0028] Target compound:

[0029] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, reacting with the solution from plunger pump I, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 1.33 g of a colorless liquid. The yield was 60%.

[0030] 1 H NMR (500MHz, CDCl3) δ4.20-4.07(m,2H),1.71(brs,2H),1.36(s,3H),1.27(t,J=7.1Hz,3H), 1.15(d,J=14.7Hz,1H), 1.07(d,J=14.8Hz,1H), 0.93(t,J=7.9Hz,9H), 0.55(q,J=7.9Hz,6H).

[0031] 13 C NMR (126MHz, CDCl3) δ178.73,61.06,57.04,29.62,25.35,14.24,7.51,4.41.

[0032] Example 2

[0033] Target compound:

[0034] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 2.64 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, reacting with the solution from reaction tube I, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 1.29 g of a colorless liquid. The yield was 70%.

[0035] 1 H NMR (500MHz, CDCl3) δ7.35(d,J=6.7Hz,5H),5.16(d,J=12.4Hz,1H),5.07(d,J=12.3Hz,1H),1.75(brs,2H) ,1.39(s,3H),1.18(d,J=14.8Hz,1H),1.10(d,J=14.6Hz,1H),0.91(t,J=7.9Hz,9H),0.54(q,J=7.9Hz,6H).

[0036] 13 C NMR (126MHz, CDCl3) δ178.51,136.00,128.69,128.37,128.25,66.87,57.22,29.47,25.32,7.52,4.41.

[0037] Example 3

[0038] Target compound:

[0039] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 2.43 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 933 mg of a colorless liquid. The yield was 53%.

[0040] 1 H NMR(500MHz, CDCl3)δ7.35(q,J=8.7,7.3Hz,5H),5.19-5.06(m,2H),3.52(dd,J=9.3,5.7Hz,1H),1.54(brs,2 H),1.09(dd,J=14.7,5.7Hz,1H),0.93(t,J=7.9Hz,9H),0.85(dd,J=14.7,9.3Hz,1H),0.57(q,J=7.9Hz,6H).

[0041] 13 C NMR (126MHz, CDCl3) δ177.55,135.95,128.72,128.41,66.70,52.03,18.40,7.51,3.84.

[0042] Example 4

[0043] Target compound:

[0044] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 1.56 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 1:1 to purify the compound and obtain 967 mg of a colorless liquid. The yield was 46%.

[0045] 1 H NMR (500MHz, CDCl3) δ7.34-7.28(m,4H),7.24-7.19(m,1H),4.05(t,J=7.4Hz,1H) ,1.80(brs,2H),1.12(h,J=7.8Hz,2H),0.87(t,J=7.9Hz,9H),0.48-0.35(m,6H).

[0046] 13 C NMR (126MHz, CDCl3) δ148.94,128.52,126.94,126.06,53.70,23.52,7.45,3.71.

[0047] Example 5

[0048] Target compound:

[0049] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, reacting with the solution from plunger pump I, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography with a PE:EA ratio of 2:1 eluent was used to purify the target compound to 1.23 g of a colorless liquid. The yield was 56%.

[0050] 1 H NMR(500MHz, CDCl3)δ4.28-3.99(m,2H),1.73(brs,2H),1.37(s,3H),1.28(t,J=7.1Hz,3 H),1.18(d,J=14.6Hz,1H),1.06(d,J=14.6Hz,1H),0.84(s,9H),0.01(d,J=23.6Hz,6H).

[0051] 13 C NMR (126MHz, CDCl3) δ178.48,61.09,57.10,30.07,26.34,25.40,16.67,14.26,-4.41,-4.92.

[0052] Example 6

[0053] Target compound:

[0054] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol) of ethyl methacrylate, 29.7 g (150 mmol) of diphenylmethylsilane, and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography with a PE:EA ratio of 2:1 eluent was used to purify the compound, yielding 1.33 g of a colorless liquid. The yield was 45%.

[0055] 1 H NMR (500MHz, CDCl3) δ7.56-7.51(m,4H),7.38-7.31(m,6H),3.97-3.86(m,1H),3.82-3.71(m,1H) ,1.78(d,J=14.8Hz,1H),1.66(d,J=14.9Hz,1H),1.34(s,3H),1.16(t,J=7.1Hz,3H),0.66(s,3H).

[0056] 13 C NMR (126MHz, CDCl3) δ178.03,134.70,134.66,129.38,129.33,127.99,127.94,61.02,57.10,30.26,27.87,14.13,-2.85.

[0057] Example 7

[0058] Target compound:

[0059] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol), 20.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce the solution from reaction tube I with a 6 mol / L hydrochloric acid solution into reactor II via plunger II at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography with a PE:EA ratio of 2:1 eluent was used to purify the compound, yielding 1.47 g of a colorless liquid. The yield was 62%.

[0060] Example 8

[0061] Target compound:

[0062] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.4 g (30 mmol) of benzophenone O-(4-methylbenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce the solution from reaction tube I with a 6 mol / L hydrochloric acid solution into reactor II using plunger pump II at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 903 mg of a colorless liquid. The yield was 41%.

[0063] Example 9

[0064] Target compound:

[0065] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 9.5 g (30 mmol) of benzophenone O-(4-fluorobenzoyl)oxime into a reaction flask, followed by 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 1.22 g of a colorless liquid. The yield was 55%.

[0066] Example 10

[0067] Target compound:

[0068] Weigh out 165 mg of photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and 8.0 g (30 mmol) of benzophenone O-isobutyryl oxime into a reaction flask, then add 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. Introduce the prepared solution into reaction tube I using plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. Continuously introduce a 6 mol / L hydrochloric acid solution into reactor II via plunger pump II, at a flow rate of 2 mL / min. Collect the solution continuously for 6 hours. Remove the solvent using a rotary evaporator and extract with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the compound and obtain 1 g of a colorless liquid. The yield was 45%.

[0069] Comparative Example 1

[0070] Target compound:

[0071] This comparative example is largely the same as Example 1, except that the photocatalyst is replaced with tris(2-phenylpyridine)iridium, specifically:

[0072] Photocatalyst Ir(ppy)3 (96 mg) and benzophenone O-(4-methoxybenzoyl) oxime (9.9 g, 30 mmol) were weighed and added to a reaction flask, followed by ethyl methacrylate (1.71 g, 15 mmol), triethylsilane (17.4 g, 150 mmol), and 600 mL of acetone. The prepared solution was introduced into reaction tube I via plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Reaction tube I was placed under a blue LED light, and the flow rate of plunger pump I was set to 1 mL / min. A 6 mol / L hydrochloric acid solution was continuously introduced into reactor II via plunger pump II at a flow rate of 2 mL / min. The solution was continuously collected for 6 hours. The solvent was removed by rotary evaporation and extracted with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and then the solvent was removed by rotary evaporation. The result was that the target product could not be synthesized.

[0073] Comparative Example 2

[0074] Target compound:

[0075] This comparative example is largely the same as Example 1, except that the photocatalyst is replaced with 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile, specifically:

[0076] Weigh out 118 mg of photocatalyst 4-CzIPN and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl) oxime into a reaction flask, followed by 1.71 g (15 mmol) of ethyl methacrylate, 17.4 g (150 mmol) of triethylsilane, and 600 mL of acetone. The prepared solution was introduced into reaction tube I via plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Reactor I was placed under a blue LED light, and the flow rate of plunger pump I was set to 1 mL / min. A 6 mol / L hydrochloric acid solution was continuously introduced into reactor II via plunger pump II at a flow rate of 2 mL / min. The solution was continuously collected for 6 hours. The solvent was removed using a rotary evaporator, and the solution was extracted with ethyl acetate (3 x 60 mL). The organic phase was dried over anhydrous sodium sulfate, and then the solvent was removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the target compound, yielding 665 mg of a colorless liquid. The yield was 30%.

[0077] Comparative Example 3

[0078] Target compound:

[0079] This comparative example is largely the same as Example 1, except that the photocatalyst is replaced with 9-thioxanthone (TXT), specifically:

[0080] Weigh out 318 mg of photocatalyst TXT and 9.9 g (30 mmol) of benzophenone O-(4-methoxybenzoyl) oxime into a reaction flask, then add 1.71 g (15 mmol), 17.4 g (150 mmol), and 600 mL of acetone. The prepared solution is introduced into reaction tube I via plunger pump I (PFA, OD 1 / 8”, ID 0.062”, 20 mL, volume = 40 mL). Place reaction tube I under a blue LED light, and set the flow rate of plunger pump I to 1 mL / min. A 6 mol / L hydrochloric acid solution is continuously introduced into reactor II via plunger pump II at a flow rate of 2 mL / min. The solution is continuously collected for 6 hours. The solvent is removed using a rotary evaporator, and the solution is extracted with ethyl acetate (3 x 60 mL). The organic phase is dried over anhydrous sodium sulfate, and then the solvent is removed by rotary evaporation. Column chromatography was performed using a PE:EA eluent of 2:1 to purify the target compound, yielding 665 mg of a colorless liquid. The yield was 30%.

Claims

1. A method for continuous flow photocatalytic synthesis of aminosilanes, characterized in that, Specifically, the following steps are included: (1) An olefin, silane, photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6, and oxime ester are mixed and dissolved in acetone. The mixed solution is then continuously fed into reactor I through pump I, and reacted under visible light irradiation and room temperature conditions. The structural formula of the olefin is: The structural formula of the silane is as follows: R is selected from aryl or ester group, and R1, R2, and R3 are selected from aryl or alkyl group; (2) The hydrochloric acid solution is continuously fed into reactor II through pump II to react with the solution after the reaction in step 1; (3) After the reaction is complete, the reaction product is collected, the solvent is removed by rotary evaporation, and the product is extracted with ethyl acetate. The organic phase is dried with anhydrous sodium sulfate, and the solvent is removed by rotary evaporation. Finally, the product is purified by column chromatography to obtain the corresponding aminosilane.

2. The method according to claim 1, characterized in that, In step (1), the olefin is ethyl methacrylate, benzyl methacrylate, benzyl acrylate or styrene.

3. The method according to claim 1, characterized in that, In step (1), the silane is triethylsilane, tert-butyldimethylsilane, diphenylmethylsilane or dimethylphenylsilane.

4. The method according to claim 1, characterized in that, In step (1), the oxime ester is selected from benzophenone O-(4-methoxybenzoyl) oxime, benzophenone O-(4-methylbenzoyl) oxime, benzophenone O-(4-fluorobenzoyl) oxime or benzophenone O-isobutyryl oxime.

5. The method according to claim 1, characterized in that, In step (1), the wavelength of visible light is 400~700 nm.

6. The method according to claim 1, characterized in that, In step (1), the molar ratio of olefin, oxime ester and silane is 1:1~2:1~10.

7. The method according to claim 1, characterized in that, In step (2), the concentration of the hydrochloric acid solution is 4~10 mol / L.

8. The method according to claim 1, characterized in that, In step (1) or (2), pump I or pump II is a plunger pump, gear pump, peristaltic pump or injection pump.

9. The method according to claim 1, characterized in that, In step (1), the reaction time is 20-60 minutes, the flow rate of the reaction solution is 0.5-2 mL / min, and the volume of reactor I is 20-60 mL.

10. The method according to claim 1, characterized in that, In step (3), the column chromatography solvent is petroleum ether and ethyl acetate in a volume ratio of 2:1 to 1:2.

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