Method for synthesizing amide through oxidative cross-coupling of aldehyde amine driven by visible light and application

Abstract

The invention discloses a method for synthesizing amide through oxidative cross-coupling of aldehyde amine driven by visible light and application, and the method comprises the following steps: S100, sequentially adding 20mg of high-crystallinity B / P co-doped g-C3N4 nanosheet, 20mg of potassium carbonate, 20mL of acetonitrile, 1mmol of aldehyde compound and 1mmol of amine compound into a quartz photoreaction flask equipped with magnetic stirring and circulating cooling water, and reacting at room temperature and normal pressure for 2-4 hours; performing dark reaction for 0.5 hour; wherein the B / P co-doped g-C3N4 nanosheet with high crystallinity is used as a heterogeneous photocatalyst; the method comprises the following steps: S101, turning on a 60W blue LED lamp for irradiation, and reacting for 12 hours under the conditions of continuous bubbling and air introduction; wherein the air introduction speed is 1-2 ml / min; and S102, centrifugally separating out the catalyst, drying an organic phase by using anhydrous magnesium sulfate, and carrying out suction filtration and rotary evaporation to obtain a target product, the visible light driven aldehyde amine oxidation cross coupling synthesized amide compound moclobemide prepared by the method can be used as an antidepressant drug and is applied to the field of medicine.

Description

Technical Field

[0001] The present invention belongs to the technical field of new material preparation, and particularly relates to a method for synthesizing amides by visible light-driven aldehyde-amine oxidative cross-coupling and its application. Background Art

[0002] The amide bond is a fundamental functional group in organic and biochemistry, widely present in natural products, polymers, and pharmaceuticals. Over 25% of known pharmaceuticals contain amide bonds, such as the antidepressant moclobemide (chemical name: 4-chloro-N-[2-(4-morpholino)ethyl]benzamide), a clinically used monoamine oxidase inhibitor (MAO-A) that selectively and reversibly inhibits MAO-A and is a clinical treatment for depression. Constructing the amide functional group is a key step in the synthesis of moclobemide. Traditional amidation reactions typically use carboxylic acids, carboxylic anhydrides, or acyl halides as acyl sources, and amines as nucleophiles for direct acid-catalyzed condensation. This process is plagued by long process steps, complex reactions, harsh conditions, high raw material costs, low reaction conversion rates, poor selectivity, difficulty in product isolation and purification, high energy consumption, and equipment corrosion. To improve reaction efficiency, various carboxylic acid activation strategies have been developed. These strategies utilize coupling agents to convert carboxylic acids into highly reactive intermediates, thereby facilitating nucleophilic attack by amines. However, these methods are often accompanied by the generation of a large number of by-products, which not only reduces the atom economy, but also increases the difficulty of post-processing and the environmental burden. Another popular method is to use urea or phosphonium reagents. To solve the waste liquid problem, researchers have developed many non-metallic catalysts for the reaction of carboxylic acids and amines to synthesize amides, mainly based on boric acid. Another option for the formation of amide bonds is the oxidative cross-coupling of aldehydes and amines. Initially, an oxidative metal catalytic process was developed, mainly using copper-based catalysts, while Milstein and his collaborators were the first to use ruthenium pincer complexes for dehydrogenation, with hydrogen as the only by-product. In order to avoid the use of metal-based catalysts, many organic catalytic methods have emerged, such as photocatalytic alternatives. A Mn3O4 catalyst was developed for the direct and highly selective synthesis of amides. Under visible light irradiation, at room temperature, with air as the oxidant, the conversion rate of amides is as high as 95%. Due to the elongation of the C-H bond (0.1115 nm) and the O-H bond (0.1002 nm) during the adsorption of hemiaminal on the Mn3O4 catalyst, and the energy barrier for the dehydrogenation of hemiaminal (-3.07 eV) is much lower than that for the dehydration (4.84 eV), the formation of imine is suppressed and amide is generated with high selectivity as the by-product H2O.

[0003] The band structure of g-C3N4 can be regulated by heteroatom doping. Boron-doped g-C3N4 has been shown to be an excellent candidate for different photocatalytic reactions. In addition to single non-metallic dopants, non-metallic co-doping has also been widely studied in g-C3N4 systems. At the same time, double-atom co-doped g-C3N4 has demonstrated that co-doping can utilize the advantages of two doping atoms to improve the efficiency of photocatalytic applications. However, single non-metallic doping or co-doping can neither increase the surface area nor reduce the thickness of g-C3N4 to enhance charge transfer and injection. To address these shortcomings, combinatorial modification of g-C3N4 is a promising approach. Summary of the Invention

[0004] To address the above-mentioned problems, the present invention proposes a method and application for synthesizing amides through visible-light-driven oxidative cross-coupling of aldehydes and amines. The method discloses the synthesis of highly crystalline B / P co-doped g-C3N4 nanosheets, and a one-pot photocatalytic oxidative cross-coupling method using the synthesized highly crystalline B / P co-doped g-C3N4 nanosheets as a heterogeneous visible-light catalyst, air as an O2 source, and a 60W blue LED lamp as a light source at room temperature and atmospheric pressure to synthesize the corresponding target amide compounds. Furthermore, the method synthesizes moclobemide through a one-pot photocatalytic oxidative cross-coupling method from p-chlorobenzaldehyde to N-(2-aminoethyl)morpholine. The method has the advantages of an atom-economical synthetic route, directly using air as an O2 source and a conventional LED lamp as a light source, high catalytic activity, good selectivity, and recyclable catalysts.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for synthesizing amides by visible light-driven oxidative cross-coupling of aldehydes and amines, comprising the following steps:

[0007] S100: In a quartz photoreaction bottle equipped with magnetic stirring and circulating cooling water, 20 mg of high crystallinity B / P co-doped g-C3N4 nanosheets, 20 mg of potassium carbonate, 20 mL of acetonitrile, 1 mmol of aldehyde compound and 1 mmol of amine compound were added in sequence, and the reaction was carried out in the dark at room temperature and normal pressure for 0.5 h; wherein the high crystallinity B / P co-doped g-C3N4 nanosheets were used as heterogeneous photocatalysts;

[0008] S101: Turn on the 60W blue LED light for irradiation and react for 12 hours under the condition of continuous bubbling of air; wherein, the air bubbling rate is 1-2 ml / min;

[0009] S102: The catalyst is separated by centrifugation, and the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the target product. The amide yield is 1.3-88.1%.

[0010] Preferably, in step S100, the aldehyde compound is one or more of benzaldehyde, p-fluorobenzaldehyde, p-methylbenzaldehyde, p-tert-butylbenzaldehyde or p-chlorobenzaldehyde; the amine compound is one or more of N-(2-aminoethyl)morpholine, N-(2-aminoethyl)piperazine or N-(2-aminoethyl)pyrrolidine.

[0011] Preferably, a method for synthesizing amides by visible light-driven oxidative cross-coupling of aldehydes and amines comprises the following steps:

[0012] S200: In a quartz photoreaction bottle equipped with magnetic stirring and circulating cooling water, 20 mg of high-crystalline B / P co-doped g-C3N4 nanosheets, 20 mg of potassium carbonate, 20 mL of acetonitrile, 1 mmol of p-chlorobenzaldehyde and 1 mmol of N-(2-aminoethyl)morpholine were added in sequence, and the reaction was carried out in the dark at room temperature and normal pressure for 0.5 h; wherein the high-crystalline B / P co-doped g-C3N4 nanosheets were used as heterogeneous photocatalysts;

[0013] S201: Turn on the 60W blue LED light for irradiation and react for 12 hours under the condition of continuous bubbling of air; wherein, the air bubbling rate is 1-2 ml / min;

[0014] S202: The catalyst is separated by centrifugation, and the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the target product. The selectivity of moclobemide is greater than 99%, and the yield is 88.1%.

[0015] Preferably, the preparation process of the high crystallinity B / P co-doped g-C3N4 nanosheets is:

[0016] S300: 10 g of melamine, 10 g of ammonium chloride, and 400 mg of boric acid were added to a mortar in sequence, the mixture was mixed and ground, and then 400 μL, 800 μL, or 1200 μL of a 50% by mass aqueous solution of ATMP was added, and the mixture was ground into a uniform white powder; wherein ATMP is aminotrimethylenephosphonic acid;

[0017] S301: Disperse the white powder in 40 mL of deionized water, stir at room temperature for 8 h, and then dry at 80°C for 24 h;

[0018] S302: Place the dried mixture into a muffle furnace and heat it to 500°C at a heating rate of 2°C / min under a nitrogen atmosphere, and keep the temperature for 3 hours; then heat it to 550°C at a heating rate of 2°C / min, and keep the temperature for 5 hours;

[0019] S303: After cooling to room temperature, the crude product was ground, washed three times with deionized water and ethanol in sequence, and dried under vacuum at 60°C for 24 hours to obtain high-crystalline B / P co-doped g-C3N4 nanosheets; the chemical structure of the high-crystalline B / P co-doped g-C3N4 nanosheets is:

[0020]

[0021] Preferably, the high crystallinity B / P co-doped g-C3N4 nanosheets are marked as B / P / PCN-1 according to the doping amount of ATMP in step S300, the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 400 μL ATMP aqueous solution are marked as B / P / PCN-2; the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 800 μL ATMP aqueous solution are marked as B / P / PCN-3.

[0022] A visible light-driven aldehyde-amine oxidative cross-coupling synthesis amide is disclosed. The visible light-driven aldehyde-amine oxidative cross-coupling synthesis amide is prepared by adopting the visible light-driven aldehyde-amine oxidative cross-coupling synthesis amide method.

[0023] The invention discloses an application of visible light-driven aldehyde-amine oxidative cross-coupling to synthesize amides. The visible light-driven aldehyde-amine oxidative cross-coupling to synthesize amides is used as a depression drug in the medical field.

[0024] After adopting the above technical solution, the present invention has the following beneficial effects:

[0025] 1. The present invention discloses the synthesis of high-crystallinity B / P co-doped g-C3N4 nanosheets, and a method for synthesizing target amide compounds by a one-pot photocatalytic oxidative cross-coupling of a series of benzaldehydes with N-(2-aminoethyl)morpholine, N-(2-aminoethyl)piperazine, and N-(2-aminoethyl)pyrrolidine using the synthesized high-crystallinity B / P co-doped g-C3N4 nanosheets as a heterogeneous visible light catalyst, air as an O2 source, and a 60W blue LED lamp as a light source at room temperature and normal pressure. The method also discloses the synthesis of moclobemide by a one-pot photocatalytic oxidative cross-coupling of p-chlorobenzaldehyde with N-(2-aminoethyl)morpholine. The method has the advantages of atom economy in the synthetic route, direct use of air as the O2 source, and an ordinary LED lamp as a light source, high catalytic system activity, good selectivity, and recyclable catalyst.

[0026] 2. Based on the design of the g-C3N4 molecular structure, this invention adopts a light element substitution strategy to covalently introduce B and P diatoms into the triazine ring structure of the g-C3N4 molecule. This modulates the intrinsic band gap and electronic band structure of g-C3N4, increasing its visible light absorption capacity, promoting the transfer and separation of photogenerated carriers, and generating more active sites, thereby improving its photoelectrochemical performance and enhancing its photocatalytic activity and selectivity. By constructing highly crystalline B / P co-doped g-C3N4 nanosheets as visible light photocatalysts, the photogenerated holes generated during the photocatalytic process, which also serve as reactive oxygen species, are used to achieve a one-pot in-situ photocatalytic oxidative cross-coupling method for the synthesis of amides with benzaldehyde and amines. Furthermore, a new low-carbon, green, one-pot synthesis method for the drug molecule moclobemide is explored, directly starting from p-chlorobenzaldehyde and N-(2-aminoethyl)morpholine via a one-step photocatalytic oxidative cross-coupling method.

[0027] 3. In the high-crystallinity B / P co-doped g-C3N4 nanosheet structure of the present invention, B and P atoms are introduced into the g-C3N4 molecular structure in the form of covalent bonds. On the one hand, by regulating the intrinsic band gap and electronic band structure of g-C3N4, the visible light absorption capacity is further increased, and the transfer and separation of photogenerated carriers are promoted. On the other hand, the Lewis acidity of the two is used as active sites to adsorb substrate aldehydes and amines, so that the molecular structure has both photocatalytic activity (triazine active center) and Lewis acid activity, and the catalytic sites of the two are spatially separated from each other, which improves the selectivity of the reaction, promotes the reaction between molecular oxygen and organic substrate aldehydes / amines at the surface interface of the active site, and promotes the timely removal of the generated amide products.

[0028] 4. The high-crystallinity B / P co-doped g-C3N4 nanosheets of the present invention present a nanosheet layer stacking morphology. The thickness of the nanosheets is about 10 to 20 nm. The nanosheets form pores with a size of 20 to 300 nm through interlayer stacking. These mesoporous to macroporous pores provide a favorable microenvironment for the reaction.

[0029] 5. The high-crystallinity B / P co-doped g-C3N4 nanosheets of the present invention are centrifuged, washed with ether and deionized water, and vacuum-dried to a constant weight, and can be recycled. The catalytic activity remains substantially unchanged after five cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the synthesis route and structure of high-crystallinity B / P co-doped g-C3N4 of the present invention;

[0031] Figure 2 FT-IR and XRD spectra of high crystallinity B / P co-doped g-C3N4 of the present invention;

[0032] Figure 3 This is a scanning electron microscope spectrum of the high-crystallinity B / P co-doped g-C3N4 of the present invention;

[0033] Figure 4 PL and TRPL images of high-crystallinity B / P co-doped g-C3N4 of the present invention;

[0034] Figure 5 Schematic diagram of the photocatalytic aldehyde / amine oxidative cross-coupling synthetic amidation reaction route and amide compound structure of the present invention;

[0035] Figure 6 GC-MS chart of the oxidative cross-coupling product of benzaldehyde and N-(2-aminoethyl)morpholine in Example 2 of the present invention;

[0036] Figure 7 GC-MS chart of the oxidative cross-coupling product of p-chlorobenzaldehyde and N-(2-aminoethyl)morpholine in Example 3 of the present invention;

[0037] Figure 8 The H NMR spectrum of moclobemide, the product in Example 3 of the present invention;

[0038] Figure 9 The carbon-1NMR spectrum of moclobemide, the product in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] like Figures 1 to 9 shown.

[0041] Example 1: Preparation of high crystallinity B / P co-doped g-C3N4 nanosheets

[0042] 10 g of melamine, 10 g of ammonium chloride and 400 mg of boric acid were added to a mortar in sequence, the mixture was mixed and ground, and then 400 μL, 800 μL or 1200 μL of a 50% by mass ATMP aqueous solution was added and ground into a uniform white powder; wherein ATMP is aminotrimethylenephosphonic acid; the white powder was dispersed in 40 mL of deionized water, stirred at room temperature for 8 hours, and dried at 80°C for 24 hours; the dried mixture was placed in a muffle furnace, heated to 500°C at a heating rate of 2°C / min under N2 atmosphere, and kept warm for 3 hours; then heated to 550°C at a heating rate of 2°C / min, and kept warm for 5 hours; after naturally cooling to room temperature, the crude product was ground, washed three times with deionized water and ethanol in sequence, and vacuum dried at 60°C for 24 hours to constant weight to obtain the target product, i.e., high-crystalline B / P co-doped g-C3N4 nanosheets. Among them, the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 400 μL ATMP aqueous solution are marked as B / P / PCN-1; the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 800 μL ATMP aqueous solution are marked as B / P / PCN-2; and the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 1200 μL ATMP aqueous solution are marked as B / P / PCN-3. The specific parameters are as follows:

[0043] B / P / PCN-1: 4.0 g, dark brown powder;

[0044] FT-IR (KBr), ν / cm -1 : 3440, 1626, 1467, 1253, 885, 811;

[0045] XRD(°):12.9, 27.4.

[0046] B / P / PCN-2: 3.6 g, dark brown powder;

[0047] FT-IR (KBr), ν / cm -1 : 3438, 1634, 1470, 1245, 888, 815;

[0048] XRD: 12.5, 27.0.

[0049] B / P / PCN-3: 3.2 g, dark brown powder;

[0050] FT-IR (KBr), ν / cm -1 : 3445, 1639, 1458, 1244, 880, 817;

[0051] XRD: 12.6, 27.2.

[0052] Example 2: Photocatalytic aldehyde / amine oxidative cross-coupling

[0053] To a quartz photoreaction flask equipped with magnetic stirring and circulating cooling water, 20 mg of photocatalyst, 20 mg of potassium carbonate, 20 ml of acetonitrile, 1 mmol of an aldehyde (benzaldehyde, p-fluorobenzaldehyde, p-methylbenzaldehyde, p-tert-butylbenzaldehyde, or p-chlorobenzaldehyde), and 1 mmol of an amine (N-(2-aminoethyl)morpholine, N-(2-aminoethyl)piperazine, or N-(2-aminoethyl)pyrrolidine) were added in sequence. Stirring was initiated and the reaction was carried out in the dark for 0.5 h. Irradiation was performed with a 60 W LED light and air was continuously bubbled in for 12 h. The mixture was allowed to stand for phase separation, and the catalyst was separated by centrifugation. The organic phase was dried over anhydrous magnesium sulfate, filtered, and rotary evaporated. The product was then quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 1.

[0054] Table 1: Photocatalytic oxidative cross-coupling of aldehydes and amines to synthesize amides

[0055]

[0056]

[0057] Example 3: Synthesis of Moclobemide by Photocatalytic Aldehyde / Amine Oxidative Cross-Coupling

[0058] To a quartz photoreaction flask equipped with magnetic stirring and circulating cooling water, 20 mg of B / P / PCN-2, 20 mg of potassium carbonate, 20 ml of acetonitrile, 1 mmol of p-chlorobenzaldehyde, and 1 mmol of N-(2-aminoethyl)morpholine were added sequentially. Stirring was initiated in the dark, shielded from light, and the reaction was allowed to proceed for 0.5 h. Illumination was initiated with a 60W LED lamp, and the reaction was continued for 12 h with continuous bubbling of air. The phases were allowed to separate, and the catalyst was separated by centrifugation. The organic phase was dried over anhydrous magnesium sulfate, filtered, and rotary evaporated. The product was then quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). Moclobemide selectivity was >99%, and the yield was 88.1%.

[0059] 1 H NMR (400MHz, Chloroform-d): δ7.72(d,J=8.5Hz,2H),7.42(d,J=8.6Hz,2H),6.76(s,1 H),3.80-3.64(m,4H),3.55(q,J=5.6Hz,2H),2.61(t,J=6.0Hz,2H),2.56-2.41(m,4H);

[0060] 13C NMR (101MHz, Chloroform-d): δ166.61, 137.84, 131.98, 131.01, 128.79, 64.20, 61.26, 34.27.

[0061] Example 4: Regeneration and recycling of B / P / PCN-2

[0062] The B / P / PCN-2 obtained by centrifugation in Example 1 was washed thoroughly with ether and deionized water in sequence, and then vacuum-dried at 60° C. to a constant weight to complete regeneration.

[0063] To a quartz photoreaction flask equipped with magnetic stirring and circulating cooling water, 20 mg of B / P / PCN-2, 20 mg of potassium carbonate, 20 ml of acetonitrile, 1 mmol of p-chlorobenzaldehyde, and 1 mmol of (N-(2-aminoethyl)morpholine) were added sequentially. Stirring was initiated and the reaction was carried out in the dark for 0.5 h in the dark. Irradiation was initiated with a 60W LED lamp, and the reaction was continued for 12 h with continuous bubbling of air. The reaction was allowed to stand for phase separation, and the catalyst was separated by centrifugation. The organic phase was dried over anhydrous magnesium sulfate, filtered, and rotary evaporated. The product was quantitatively analyzed by gas chromatography-mass spectrometry. In the first cycle, moclobemide was used at >99% yield, resulting in a yield of 87.3%. In the second cycle, moclobemide was used at >99% yield, resulting in a yield of 88.0%. In the third cycle, moclobemide was used at >99% yield, resulting in a yield of 87.5%. In the fourth cycle, moclobemide was used at >99% yield, resulting in a yield of 87.0%. In the fifth cycle, moclobemide was used at >99% yield, resulting in a yield of 87.1%.

[0064] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for synthesizing amides by oxidative cross-coupling of aldehydes and amines driven by visible light, characterized in that: The following steps are involved: S100: In a quartz photoreaction bottle equipped with magnetic stirring and circulating cooling water, 20 mg of high crystallinity B / P co-doped g-C3N4 nanosheets, 20 mg of potassium carbonate, 20 mL of acetonitrile, 1 mmol of aldehyde compound and 1 mmol of amine compound were added in sequence, and the reaction was carried out in the dark at room temperature and normal pressure for 0.5 h; wherein the high crystallinity B / P co-doped g-C3N4 nanosheets were used as heterogeneous photocatalysts; S101: Turn on the 60W blue LED light for irradiation and react for 12 hours under the condition of continuous bubbling of air; wherein, the air bubbling rate is 1-2 ml / min; S102: The catalyst is separated by centrifugation, and the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the target product. The amide yield is 1.3-88.1%.

2. The method for synthesizing amides by visible light-driven oxidative cross-coupling of aldehydes and amines according to claim 1, wherein: In step S100, the aldehyde compound is one or more of benzaldehyde, p-fluorobenzaldehyde, p-methylbenzaldehyde, p-tert-butylbenzaldehyde or p-chlorobenzaldehyde; the amine compound is one or more of N-(2-aminoethyl)morpholine, N-(2-aminoethyl)piperazine or N-(2-aminoethyl)pyrrolidine.

3. The method for synthesizing amides by visible light-driven aldehyde-amine oxidative cross-coupling according to claim 1, wherein: The following steps are involved: S200: In a quartz photoreaction bottle equipped with magnetic stirring and circulating cooling water, 20 mg of high-crystalline B / P co-doped g-C3N4 nanosheets, 20 mg of potassium carbonate, 20 mL of acetonitrile, 1 mmol of p-chlorobenzaldehyde and 1 mmol of N-(2-aminoethyl)morpholine were added in sequence, and the reaction was carried out in the dark at room temperature and normal pressure for 0.5 h; wherein the high-crystalline B / P co-doped g-C3N4 nanosheets were used as heterogeneous photocatalysts; S201: Turn on the 60W blue LED light for irradiation and react for 12 hours under the condition of continuous bubbling of air; wherein, the air bubbling rate is 1-2 ml / min; S202: The catalyst is separated by centrifugation, and the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the target product. The selectivity of moclobemide is greater than 99%, and the yield is 88.1%.

4. A method for synthesizing amides by visible light-driven oxidative cross-coupling of aldehydes and amines according to any one of claims 1 or 3, characterized in that: The preparation process of the high crystallinity B / P co-doped g-C3N4 nanosheets is as follows: S300: 10 g of melamine, 10 g of ammonium chloride, and 400 mg of boric acid were added to a mortar in sequence, the mixture was mixed and ground, and then 400 μL, 800 μL, or 1200 μL of a 50% by mass aqueous solution of ATMP was added, and the mixture was ground into a uniform white powder; wherein ATMP is aminotrimethylenephosphonic acid; S301: Disperse the white powder in 40 mL of deionized water, stir at room temperature for 8 h, and then dry at 80°C for 24 h; S302: Place the dried mixture into a muffle furnace and heat it to 500°C at a heating rate of 2°C / min under a nitrogen atmosphere, and keep the temperature for 3 hours; then heat it to 550°C at a heating rate of 2°C / min, and keep the temperature for 5 hours; S303: After cooling to room temperature, the crude product was ground, washed three times with deionized water and ethanol in sequence, and dried under vacuum at 60°C for 24 hours to obtain high-crystalline B / P co-doped g-C3N4 nanosheets; the chemical structure of the high-crystalline B / P co-doped g-C3N4 nanosheets is:

5. The method for synthesizing amides by visible light-driven oxidative cross-coupling of aldehydes and amines according to claim 4, characterized in that: The high crystallinity B / P co-doped g-C3N4 nanosheets are labeled as B / P / PCN-1 according to the doping amount of ATMP in step S300. The high crystallinity B / P co-doped g-C3N4 nanosheets doped with 400 μL ATMP aqueous solution are labeled as B / P / PCN-2; the high crystallinity B / P co-doped g-C3N4 nanosheets doped with 800 μL ATMP aqueous solution are labeled as B / P / PCN-3.

6. A visible light-driven oxidative cross-coupling of aldehydes and amines to synthesize amides, characterized by: The visible light-driven aldehyde-amine oxidative cross-coupling synthesis of amide is prepared by a visible light-driven aldehyde-amine oxidative cross-coupling synthesis of amide according to any one of claims 1 to 5.

7. A use of the visible light-driven aldehyde-amine oxidative cross-coupling to synthesize amides as claimed in claim 6, characterized in that: The visible light-driven aldehyde-amine oxidative cross-coupling to synthesize amides is used as antidepressant drugs in the medical field.

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