Method for selectively synthesizing N-formamide or N-methylamine compound

Abstract

The invention discloses a method for selectively synthesizing an N-formamide or N-methylamine compound, which comprises the following steps: by taking an amine compound and carbon dioxide as raw materials, phenylsilane as a reducing agent and a phenoxide ion pair catalyst provided by the invention, synthesizing the N-formamide or N-methylamine compound by adjusting the pressure of the carbon dioxide and the reaction temperature. And N-formamide and N-methylamine compounds can be selectively obtained. According to the method, raw materials of the catalyst are cheap and easy to obtain, synthesis is simple, reduction reaction conditions are mild, and the method is a potential way for fixing carbon dioxide.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic catalysis, and particularly relates to a method for selectively synthesizing N-formamide or N-methyl amine compounds. BACKGROUND

[0002] The catalytic conversion of carbon dioxide into value-added chemicals is one of the important methods to reduce the concentration of atmospheric carbon dioxide. Carbon dioxide is divided into non-reduction conversion and reduction conversion. The main products of non-reduction conversion are cyclic carbonates, polycarbonates, urea, etc., and the reduction products are formic acid, methanol, methane, etc. This direct reduction method usually has harsh conditions and single product. Therefore, the combination of carbon dioxide reduction and C-N bond reduction method is a conversion method for expanding the conversion of carbon dioxide into value-added chemicals. The functional reduction reaction of carbon dioxide and reducing agent with amine has two main products, N-formylation product and N-methylation product. The N-formylation product can be used as a solvent and a pesticide intermediate, and the generation of N-methylation product provides a sustainable idea for common N-methylation reagents such as iodomethane. The common reducing agent is hydrogen, but the reaction usually accompanies high pressure and the conditions are not mild. Therefore, the selection of hydrogen silane as the reducing agent is the best reducing agent to realize the reaction.

[0003] Due to the thermodynamic stability and kinetic inertness of carbon dioxide, selecting a suitable catalyst is the key of the present application. In previous reports, metal-containing catalysts exhibit better catalytic activity, but the reaction is harsh (Eur J Org Chem 2019 (2019) 2437-2447, Chem. – Asian J. 19 (2024) e202400497). Therefore, designing an organic catalyst that can catalyze the functional reduction of amine participating in carbon dioxide with hydrogen silane as the reducing agent under mild conditions has become a recent research hotspot. SUMMARY

[0004] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0006] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for selectively synthesizing N-formamide or N-methyl amine compounds.

[0007] To solve the above technical problems, the application provides a method for selectively synthesizing N-formamide or N-methyl amine compounds, characterized by comprising the following steps: adding an amine compound, phenylsilane, a phenol salt ion pair catalyst and an organic solvent into a reactor, controlling the reaction temperature to be 25-80 DEG C, introducing carbon dioxide, the pressure being 0.1 MPa-1 MPa, and the reaction time being 3-12 h; and after the reaction is completed, the reaction liquid is purified by chromatography to obtain N-formamide shown in formula (1) or N-methyl amine shown in formula (2). Formula (1); Formula (2); Wherein, R1, R3 are selected from phenyl, functional group-substituted phenyl, alkyl; R2, R4 are selected from hydrogen, alkyl, phenyl.

[0008] As a preferred scheme of the method, the amine compound is primary amine shown in formula (3) or secondary amine shown in formula (4). Formula (3); Formula (4); Wherein, R5 is selected from phenyl, p-methoxyphenyl, p-chlorophenyl; R6 is selected from ethyl, phenyl, p-methoxyphenyl, p-chlorophenyl; R7 is selected from hydrogen, methyl, ethyl, phenyl.

[0009] As a preferred scheme of the method, the chemical structural formula of the phenol salt ion pair catalyst is shown in formula (5). Formula (5) Wherein, R8, R9, R10, R11, R12 are selected from hydrogen, halogen, branched or straight chain alkyl or alkoxy with 1-4 carbon atoms, trifluoromethyl, and R8, R9, R10, R11, R12 are the same or different groups.

[0010] As a preferred scheme of the method, the organic solvent is acetonitrile.

[0011] As a preferred scheme of the method, the molar ratio of the amine compound to phenylsilane is 1:2-4.

[0012] As a preferred scheme of the method, the molar ratio of the amine compound to the phenol salt ion pair catalyst is 1:0.02-0.1.

[0013] As a preferred scheme of the method, the molar concentration of the amine compound in the organic solvent is 0.25-0.5 mol / L.

[0014] The present application has the following beneficial effects: (1) The present application uses phenolate ion pair catalyst, which has high catalytic activity, can efficiently catalyze the functional reduction reaction of carbon dioxide with amine under mild conditions. The method has wide applicability, high yield, high safety, no halogen, is environmentally friendly, and has certain application prospect in the field of fine chemicals.

[0015] (2) The catalyst used in the present application has low cost of synthesis raw materials, and the synthesis is simple. The reaction can be completed in one step at normal temperature and pressure, and the subsequent purification is convenient. The organic base phenolate catalytic reaction is simple and safe in operation, and is suitable for future industrialized production. At the same time, the catalytic system is simple and can be recycled. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them: Figure 1 Catalyst 1 in the embodiments of the present application 1 H NMR spectrum.

[0017] Figure 2 Catalyst 2 in the embodiments of the present application 1 H NMR spectrum.

[0018] Figure 3 Catalyst 3 in the embodiments of the present application 1 H NMR spectrum.

[0019] Figure 4 Compound N-methyl-N-formanilide in the embodiments of the present application 1 H NMR spectrum.

[0020] Figure 5 Compound N-methyl-N-formanilide in the embodiments of the present application 13 C NMR spectrum.

[0021] Figure 6 Compound N-formylindole in the embodiments of the present application 1 H NMR spectrum.

[0022] Figure 7 Compound N-formylindole in the embodiments of the present application 13 C NMR spectrum.

[0023] Figure 8 Compound N-n-octylformamide in the embodiments of the present application1 H NMR spectrum.

[0024] Figure 9 The compound described in this invention is N-n-octylformamide. 13 C NMR spectrum.

[0025] Figure 10 The compound 4'-methoxyformylaniline in the embodiments of the present invention 1 H NMR spectrum.

[0026] Figure 11 The compound 4'-methoxyformylaniline in the embodiments of the present invention 13 C NMR spectrum.

[0027] Figure 12 The compound in this embodiment is 1-methylindoline. 1 H NMR spectrum.

[0028] Figure 13 The compound in this embodiment is 1-methylindoline. 13 C NMR spectrum.

[0029] Figure 14 The compound N,N-dimethylaniline in the embodiments of this invention 1 H NMR spectrum.

[0030] Figure 15 The compound N,N-dimethylaniline in the embodiments of this invention 13 C NMR spectrum. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] The raw materials used in the embodiments of the present application are commercially available unless otherwise specified. The hydrogen nuclear magnetic resonance spectrum and carbon spectrum involved in the embodiments are determined by using a Bruker Ascend TM-400 nuclear magnetic resonance analyzer of Bruker Company. The deuterated reagent used is deuterated chloroform (CDCl3). The conversion rate and yield in the embodiments are determined by nuclear magnetic resonance. Details are shown in Table 1.

[0035] Table 1 ; Example 1 (1) The preparation method of the catalyst 1 is as follows: at room temperature, in a 50 ml reaction bottle, using p-methoxyphenol (5 mmol, 0.62 g) and tetrabutylammonium hydroxide (5 mmol, 1.2 g) as raw materials, stirring in tetrahydrofuran (5 mL) overnight, and solid is precipitated, washed with ether for 3 times. Vacuum drying for 12 hours to obtain the catalyst 1 (1.75 g, 96%).

[0036] The spectrum data are as follows: 1 H NMR (400 MHz, CDCl3) δ 6.85 – 6.76 (m, 2H), 6.71 – 6.60(m, 2H), 3.68 (s, 3H), 3.25 – 3.16 (m, 8H), 1.37 (h, J = 7.3 Hz, 8H), 0.95(t, J = 7.3 Hz, 12H). (2) At room temperature, in a 25 mL stainless steel reaction kettle, N-methylaniline (0.5 mmol) and catalyst 1 (3.6 mg, 2 mol%) are sequentially added, acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) are added, then the gas is replaced by double-tube and 0.5 Mpa carbon dioxide gas is filled, and the reaction is carried out at 25°C for 3 hours. After the reaction is completed, the reaction kettle is cooled to room temperature in an ice bath, and the carbon dioxide in the reaction kettle is slowly released. Uniform trimethoxybenzene (84 mg, 0.5 mmol) is added to the reaction solution, and the yield is determined by H NMR. The yield is 95%. 1 H NMR (400 MHz, CDCl3) δ 6.85 – 6.76 (m, 2H), 6.71 – 6.60(m, 2H), 3.68 (s, 3H), 3.25 – 3.16 (m, 8H), 1.37 (h, J = 7.3 Hz, 8H), 0.95(t, J = 7.3 Hz, 12H).

[0037] The product is separated and purified by column chromatography to obtain N-methyl-N-formyl aniline. The spectrum data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.44 (s, 1H), 7.44 – 7.33 (m, 2H), 7.28 – 7.19 (m, 1H),7.18 – 7.08 (m, 2H), 3.29 (s, 3H).

[0038] Example 2 (1) The preparation method of catalyst 2 is as follows: under room temperature conditions, in a 50 ml reaction bottle, phenol (5 mmol, 0.47 g) and tetrabutylammonium hydroxide (5 mmol, 1.2 g) are used as raw materials, tetrahydrofuran (5 mL) is used as solvent, stirring overnight, solid is precipitated, washed with ether for 3 times. Vacuum drying for 12 hours to obtain catalyst 1 (1.62 g, 97%).

[0039] The spectrum data is as follows: 1 H NMR (400 MHz, CDCl3) δ 7.05 (td, J = 8.5, 3.2 Hz, 2H),6.94 – 6.86 (m, 2H), 6.66 –6.59 (m, 1H), 3.18 – 3.07 (m, 9H), 1.55 – 1.41 (m,9H), 1.33 (q, J = 7.4 Hz, 8H), 0.91 (td, J = 7.3, 3.4 Hz, 12H). (2) Under room temperature conditions, in a 25 mL stainless steel reaction kettle, N-methylaniline (0.5 mmol) is added, then catalyst 2 (3.4 mg, 2 mol%) is added, acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) are added, then the gas is replaced by double pipe, 0.5 Mpa carbon dioxide gas is filled, and the reaction is carried out at 25°C for 3 hours. After the reaction is completed, the reaction kettle is cooled to room temperature in an ice bath, and the carbon dioxide in the reaction kettle is slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) is added, and the yield is determined by H NMR. The yield is 82%. The product is separated and purified by column chromatography to obtain N-methyl-N-formyl aniline. 1 H NMR (400 MHz, CDCl3) δ 7.05 (td, J = 8.5, 3.2 Hz, 2H),6.94 – 6.86 (m, 2H), 6.66 –6.59 (m, 1H), 3.18 – 3.07 (m, 9H), 1.55 – 1.41 (m,9H), 1.33 (q, J = 7.4 Hz, 8H), 0.91 (td, J = 7.3, 3.4 Hz, 12H).

[0040] Example 3 (1) The preparation method of catalyst 3 is as follows: under room temperature conditions, in a 50 ml reaction bottle, p-chlorophenol (5 mmol, 0.64 g) and tetrabutylammonium hydroxide (5 mmol, 1.2 g) are used as raw materials, tetrahydrofuran (5 mL) is used as solvent, stirring overnight, solid is precipitated, washed with ether for 3 times. Vacuum drying for 12 hours to obtain catalyst 1 (1.75 g, 95%).

[0041] The spectrum data is as follows: 1H NMR (400 MHz, CDC13) δ 7.11 - 7.03 (m, 2H), 6.84 (d, J = 8.7 Hz, 2H), 3.34 - 3.25 (m, 8H), 1.63 (dt, J = 15.1, 8.7 Hz, 9H), 1.44 (h, J = 7.4 Hz, 8H), 1.01 (t, J = 7.3 Hz, 12H). (2) At room temperature, 4-methoxy-N-methylaniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were sequentially added into a 25 mL stainless steel autoclave, then the gas was replaced by double-tube and filled with 0.5 MPa carbon dioxide gas, and reacted at 25°C for 3 hours. After the reaction was completed, the reaction autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction autoclave was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the yield was determined by 1H NMR. The yield was 96%. 1 The yield was determined by 1H NMR. The yield was 76%. The product was separated and purified by column chromatography to obtain N-methyl-N-formyl aniline.

[0042] Example 4 (2) At room temperature, 4-methoxy-N-methylaniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were sequentially added into a 25 mL stainless steel autoclave, then the gas was replaced by double-tube and filled with 0.5 MPa carbon dioxide gas, and reacted at 25°C for 3 hours. After the reaction was completed, the reaction autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction autoclave was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the yield was determined by 1H NMR. The yield was 96%.

[0043] The product was separated and purified by column chromatography to obtain 4'-methoxy-N-methyl formanilide, and the spectral data was: 1 HNMR (400 MHz, CDC13) δ 8.33 (s, 1H), 7.09 (d, J = 9.0 Hz, 2H), 6.94 - 6.89 (m, 2H), 3.81 (s, 3H), 3.26 (d, J = 0.6 Hz, 3H). Example 5 Under the condition of room temperature, 4'-chloro-N-methyl aniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were sequentially added into a 25 mL stainless steel autoclave, then the gas was replaced by double pipe and filled with 0.5 Mpa carbon dioxide gas, and reacted at 25°C for 12 hours. After the reaction was completed, the reaction autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction autoclave was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the product was separated and purified by column chromatography to obtain 4'-chloro-N-methyl formanilide, and the spectrum data was as follows: 1 The yield was determined by H NMR, and the yield was 98%.

[0044] The product was separated and purified by column chromatography to obtain N-ethyl formanilide, and the spectrum data was as follows: 1 H NMR (400 MHz, CDCl3) δ 8.36 (s, 1H), 7.42 (ddd, J = 8.1, 6.7, 1.3 Hz, 2H), 7.33 – 7.27 (m, 1H), 7.20 – 7.13 (m, 2H), 3.87 (q, J = 7.2 Hz, 2H), 1.16 (t, J = 7.2 Hz, 3H). Example 6 Under the condition of room temperature, N-ethyl aniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were sequentially added into a 25 mL stainless steel autoclave, then the gas was replaced by double pipe and filled with 0.5 Mpa carbon dioxide gas, and reacted at 25°C for 3 hours. After the reaction was completed, the reaction autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction autoclave was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the product was separated and purified by column chromatography to obtain N-ethyl formanilide, and the spectrum data was as follows: 1 The yield was determined by H NMR, and the yield was 68%.

[0045] The product was separated and purified by column chromatography to obtain N-ethyl formanilide, and the spectrum data was as follows: 1 H NMR (400 MHz, CDCl3) δ 8.36 (s, 1H), 7.42 (ddd, J = 8.1, 6.7, 1.3 Hz, 2H), 7.33 – 7.27 (m, 1H), 7.20 – 7.13 (m, 2H), 3.87 (q, J = 7.2 Hz, 2H), 1.16 (t, J = 7.2 Hz, 3H). Example 7 Under the condition of room temperature, in 25 mL stainless steel reactor, indoline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were added in turn, then the gas was replaced by double pipe, 0.5 Mpa carbon dioxide gas was filled, and the reaction was carried out at 25°C for 12 hours. After the reaction was completed, the reactor was cooled to room temperature in ice bath, and the carbon dioxide in the reactor was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the product was separated and purified by column chromatography to obtain N-formylindole, and the spectrum data was as follows: 1 The yield was determined by H NMR, and the yield was 81%.

[0046] The product was separated and purified by column chromatography to obtain N-formylindole, and the spectrum data was as follows: 1 H NMR (400 MHz, CDCl3) δ 8.93 (s, 1H), 7.26 - 7.14 (m, 3H), 7.07 - 7.02 (m, 1H), 4.13 - 4.04 (m, 2H), 3.20 - 3.12 (m, 2H). Example 8 Under the condition of room temperature, in 25 mL stainless steel reactor, n-octylamine (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 μL, 1 mmol) were added in turn, then the gas was replaced by double pipe, 0.5 Mpa carbon dioxide gas was filled, and the reaction was carried out at 25°C for 3 hours. After the reaction was completed, the reactor was cooled to room temperature in ice bath, and the carbon dioxide in the reactor was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the product was separated and purified by column chromatography to obtain N-n-octylformamide, and the spectrum data was as follows: 1 The yield was determined by H NMR, and the yield was 99%.

[0047] The product was separated and purified by column chromatography to obtain N-n-octylformamide, and the spectrum data was as follows: 1 H NMR (400MHz, CDCl3) δ 8.16 - 7.96 (m, 1H), 5.97 (s, 1H), 3.30 - 3.12 (m, 2H), 1.49 (p, J = 7.2 Hz, 2H), 1.34 - 1.19 (m, 11H), 0.89 - 0.79 (m, 3H). Example 9 Under the condition of room temperature, 4'-methoxyaniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (1 mL) and phenylsilane (124 µL, 1 mmol) were added into a 25 mL stainless steel autoclave in turn, then the gas was replaced by double-tube and filled with 0.5 Mpa carbon dioxide gas, and reacted at 25°C for 3 hours. After the reaction was completed, the autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the autoclave was slowly released. Uniform trimethoxybenzene (84 mg, 0.5 mmol) was added to the reaction solution, and the product was separated and purified by column chromatography. 1 The yield was determined by H NMR, and the yield was 95%.

[0048] The product was separated and purified by column chromatography to obtain 4'-methoxyformanilide, and the spectrum data were as follows: 1 H NMR (400MHz, CDCl3) δ 8.31 (t, J = 1.9 Hz, 1H), 7.48 – 7.40 (m, 1H), 7.11 – 6.96 (m,1H), 6.87 (ddd, J = 11.4, 9.0, 2.0 Hz, 2H), 3.79 (dd, J = 5.8, 1.3 Hz, 3H). Example 10 Under the condition of room temperature, N-methylaniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (2 mL) and phenylsilane (248 µL, 2 mmol) were added into a 10 mL Schlenk tube in turn, then the gas was replaced by double-tube, and a carbon dioxide balloon was connected to the Schlenk branch. The reaction was carried out at 60°C for 6 hours. After the reaction was completed, the autoclave was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction tube was slowly released. Uniform trimethoxybenzene (84 mg, 0.5 mmol) was added to the reaction solution, and the product was separated and purified by column chromatography. 1 The yield was determined by H NMR, and the yield was 95%.

[0049] The product was separated and purified by column chromatography to obtain N,N-dimethylaniline, and the spectrum data were as follows: 1 H NMR (400MHz, CDCl3) δ 7.26 – 7.21 (m, 2H), 6.76 – 6.69 (m, 3H), 2.93 (s, 6H). Example 11 Under room temperature, in a 10 mL Schlenk tube, add indoline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (2 mL) and phenylsilane (248 μL, 2 mmol) in sequence, then replace the gas by double-tube, connect a carbon dioxide balloon to the Schlenk branch, react at 60 °C for 6 hours, after the reaction is completed, cool the reaction kettle to room temperature in an ice bath, slowly release the carbon dioxide in the reaction tube. Add mesitylene (84 mg, 0.5 mmol) to the reaction solution, determine the yield by 1H NMR, and the yield is 90%.

[0050] The product is separated and purified by column chromatography to obtain 1-methylindoline, and the spectrum data are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.15 - 7.06 (m, 2H), 6.68 (td, J = 7.4, 1.0 Hz, 1H), 6.50 (dd, J = 8.1, 1.0 Hz, 1H), 3.30 (t, J = 8.3 Hz, 2H), 3.02 - 2.90 (m, 2H), 2.77 (s, 3H). Example 12 Under room temperature, in a 10 mL Schlenk tube, add morpholine (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (2 mL) and phenylsilane (248 μL, 2 mmol) in sequence, then replace the gas by double-tube, connect a carbon dioxide balloon to the Schlenk branch, react at 60 °C for 6 hours, after the reaction is completed, cool the reaction kettle to room temperature in an ice bath, slowly release the carbon dioxide in the reaction tube. Add mesitylene (84 mg, 0.5 mmol) to the reaction solution, determine the yield by 1H NMR, and the yield is 89%.

[0051] The product is separated and purified by column chromatography to obtain N-methylmorpholine, and the spectrum data are as follows: 1 H NMR (400 MHz, CDCl3) δ 3.74 - 3.67 (m, 4H), 2.44 - 2.33 (m, 4H), 2.27 (s, 3H). Example 13 Under room temperature, in a 10 mL Schlenk tube, 4'-methoxyaniline (0.5 mmol), catalyst 1 (3.6 mg, 2 mol%), acetonitrile (2 mL) and phenylsilane (496 μL, 4 mmol) were added in turn, then the gas was replaced by double-tube, a carbon dioxide balloon was connected to the Schlenk branch, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the reaction kettle was cooled to room temperature in an ice bath, and the carbon dioxide in the reaction tube was slowly released. To the reaction solution, mesitylene (84 mg, 0.5 mmol) was added, and the yield was determined by 1H NMR. The yield was 82%.

[0052] The product was separated and purified by column chromatography to obtain (4-methoxyphenyl)-dimethylamine. The spectrum data are as follows: 1 H NMR (400 MHz, CDCl3) δ 7.14 - 7.05 (m, 2H), 6.77 - 6.69 (m, 2H), 2.94 (s, 6H), 2.30 (s, 3H). It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be included in the scope of the present application.

Claims

1. A method for selectively synthesizing N-formamides or N-methylamines, characterized by: The amine compound, phenylsilane, phenolate ion pair catalyst, and organic solvent are added into a reactor, the reaction temperature is controlled at 25-80 DEG C, carbon dioxide is introduced, the pressure is 0.1-1 MPa, and the reaction time is 3-12 h; after the reaction is completed, the reaction liquid is purified by chromatography to obtain the N-formamide shown in formula (1) or the N-methyl amine compound shown in formula (2); wherein R 1 , R 3 are selected from phenyl, phenyl substituted with a functional group, alkyl; R 2 , R 4 are selected from hydrogen, alkyl, phenyl.

2. The method of claim 1, wherein: The amine compound is a primary amine shown in formula (3) or a secondary amine shown in formula (4); Among them, R 5 Selected from phenyl, p-methoxyphenyl, p-chlorophenyl; R 6 Selected from ethyl, phenyl, p-methoxyphenyl, p-chlorophenyl; R 7 Selected from hydrogen, methyl, ethyl, and phenyl.

3. The method of claim 1 or 2, wherein: The chemical structural formula of the phenolate ion pair catalyst is shown in formula (5): wherein R 8 , R 9 , R 10 , R 11 , R 12 are selected from hydrogen, halogen, branched or straight chain alkyl or alkoxy of 1 to 4 carbon atoms, trifluoromethyl, R 8 , R 9 , R 10 , R 11 , R 12 are the same or different radicals.

4. The method of claim 1, wherein: The organic solvent is acetonitrile.

5. The method of claim 1, wherein: The molar ratio of the amine compound and phenylsilane is 1:2-4.

6. The method of claim 5, wherein: The molar ratio of the amine compound and phenylsilane is 1:2-4.

7. The method of claim 6, wherein: The molar concentration of the amine compound in the organic solvent is 0.25-0.5 mol / L. The molar ratio of the amine compound and phenylsilane is 1:2-4. The molar ratio of the amine compound and phenylsilane is 1:2-4. The molar concentration of the amine compound in the organic solvent is 0.25-0.5 mol / L.

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