Method for photoinduced nitro reduction catalyzed by ferric chloride

Abstract

The present invention discloses a method for photoinduced nitro reduction catalyzed by ferric chloride, belonging to the field of pharmaceutical compound synthesis. The method provided by the present invention primarily utilizes a transition metal salt as a catalyst for the primary reaction, with an inorganic acid or an organic acid as an additive, to achieve nitro reduction to amino groups under air or nitrogen conditions. The method has high catalytic efficiency and a high yield of the reduction product, significantly reducing production costs and being suitable for the synthesis and amplification of later-stage compounds. The method does not require expensive metal catalysts or reducing agents, has a simple preparation process, and is highly efficient, environmentally friendly, safe, and cost-effective.

Description

Technical Field

[0001] The present invention relates to a method for preparing an amino compound from a nitro compound, in particular to a method for reducing a nitro group to an amino group by photoinitiation catalyzed by ferric chloride. Background Art

[0002] Aromatic amines are important organic chemical raw materials and intermediates for the synthesis of many fine chemicals. They are widely used in industries such as dyes, pharmaceuticals, pesticides, surfactants, textile auxiliaries, chelating agents, and polymer materials. A representative product, aniline, has an annual global production of approximately 1.6 million tons. Traditional methods for reducing nitro compounds to produce aromatic amines include catalytic hydrogenation, metal reduction, and alkaline sulfide reduction. Catalytic hydrogenation often uses transition metals such as iron, cobalt, nickel, copper, palladium, rhodium, platinum, and gold supported on activated carbon, microporous silica gel, activated alumina, or SiO2 as catalysts. The reduction reaction proceeds under high temperature and high pressure. Metal reduction typically uses metals such as Al, Fe, Zn, and Sn to reduce nitro compounds in an acidic aqueous solution. Alkaline sulfide reduction often uses alkaline sulfides such as Na2S, NaHS, and Na2S2 to convert nitro groups to amino groups. Catalytic hydrogenation requires high temperature, high pressure, and a large amount of energy input, which poses safety risks. Both metal reduction and alkaline sulfide reduction methods produce harmful gases and wastewater, posing serious risks to the ecological environment and human health. Therefore, we need new green, safe and environmentally friendly methods to achieve such transformations. New progress has been developed, including biocatalytic reduction, electrocatalytic reduction, photocatalytic reduction, etc. Biocatalytic reduction achieves the reduction of nitroaromatic compounds under mild conditions, but the biocatalytic method will produce a large amount of by-products. Electrocatalytic nitro reduction has also made some progress, but the promotion of this technology from the laboratory to the industrial scale faces both technical and economic challenges. In recent years, photocatalytic reduction has received widespread attention. Traditional photocatalytic reactions require the use of expensive and difficult-to-obtain photosensitizers. Compared with biocatalysis and electrocatalysis, photocatalysis has the advantages of low energy consumption, high reaction activity and catalytic efficiency, and wide applicability. Here we report a more environmentally friendly, green and cheap TMSCl-mediated FeCl3-catalyzed photoexcitation to achieve the reduction reaction type of nitro to amino. Summary of the Invention

[0003] In order to overcome the above technical defects, the present invention provides a method for catalyzing the photoinduced reduction of nitro groups to amino groups using ferric chloride to solve the problems of expensive catalysts, safety, and environmental protection during the nitro reduction reaction.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A method for photoinduced reduction of nitro groups to amino groups catalyzed by ferric chloride comprises the following steps: dissolving a nitro compound represented by formula (1) in a solvent at room temperature, adding a catalyst and an additive, and performing a light irradiation reaction to obtain an amino product represented by formula (2);

[0006] ;

[0007] In formula (1) and formula (2), when X1, X2, X3 = C, a benzene ring is formed; R1, R2, R3 are one or more of cyano, halogenated alkyl, aryl, and halogen; R4 and R5 are one or more of hydrogen, halogen, and halogenated alkyl;

[0008] When X1=N, X2, X3=C, a pyridine ring is formed; R2, R5 are one or more of halogen and alkyl; R1 is one of hydrogen, halogen and alkyl, R3 is halogen, and R4 is hydrogen;

[0009] When X1, X2 = N, X3 = C, a pyrimidine ring is formed, R1, R5 are one or more of halogen, alkyl, and ester groups; R3 is one of halogen and alkyl, and R2 and R4 are hydrogen;

[0010] When X1, X3 = N, X2 = C, a pyrazine ring is formed, R3 is a halogen; R1, R2, R4, R5 are hydrogen.

[0011] Furthermore, the alkyl group is a methyl group, the ester group is ethyl formate, the halogenated alkyl group is a trifluoromethyl group, and the halogen is one or more of fluorine, chlorine, and bromine.

[0012] Furthermore, the catalyst is selected from one of ferrous chloride and ferric chloride.

[0013] Furthermore, the additive is selected from one of hydrochloric acid, oxalyl chloride, trimethylchlorosilane, and tetrabutylammonium chloride.

[0014] Furthermore, the solvent is dichloromethane, N,N-dimethylformamide, acetonitrile or a mixture of acetonitrile and water with a volume ratio of 2:1 to 200:1.

[0015] Furthermore, the wavelength range of the light for the illumination reaction is 365-455 nm.

[0016] Furthermore, the molar ratio of the nitro compound of formula (1) to the catalyst is 5:1 to 1:2.

[0017] Furthermore, the molar ratio of the nitro compound of formula (1) to trimethylchlorosilane is 1:1 to 1:4.

[0018] Furthermore, the light irradiation reaction time is 8 to 48 hours.

[0019] Furthermore, the atmosphere condition is nitrogen condition.

[0020] Through the above technical solution, the beneficial effects of the present invention are as follows:

[0021] (1) The preparation method provided by the present invention is green, environmentally friendly, safe, and does not involve the use of reducing agents;

[0022] (2) The preparation method provided by the present invention is simple to operate. No expensive metal catalysts or reducing agents are required for the reduction reaction, and the process is simple and the cost is low.

[0023] (3) The preparation method provided by the present invention is highly efficient. Under a nitrogen atmosphere, the catalytic efficiency of the catalyst and the yield of the reduction product are significantly improved, making it suitable for the synthesis and amplification of subsequent compounds, and also greatly reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The product prepared in Example 1 1 H NMR spectrum;

[0025] Figure 2 The product prepared in Example 4 1 H NMR spectrum;

[0026] Figure 3 The product prepared in Example 5 1 H NMR spectrum;

[0027] Figure 4 The product prepared in Example 8 1 H NMR spectrum;

[0028] Figure 5 The product prepared in Example 9 1 H NMR spectrum;

[0029] Figure 6 The product prepared in Example 11 1 H NMR spectrum;

[0030] Figure 7 The product prepared in Example 12 1 H NMR spectrum;

[0031] Figure 8 The product prepared in Example 13 1 H NMR spectrum;

[0032] Figure 9 The product prepared in Example 14 13 C NMR spectrum;

[0033] Figure 10 The product prepared in Example 15 1H NMR spectrum;

[0034] Figure 11 The product prepared in Example 16 1 H NMR spectrum;

[0035] Figure 12 The product prepared in Example 17 1 H NMR spectrum;

[0036] Figure 13 The product prepared in Example 19 1 H NMR spectra;

[0037] Figure 14 The product prepared in Example 31 1 H NMR spectra;

[0038] Figure 15 The product prepared in Example 36 1 H NMR spectra;

[0039] Figure 16 The product prepared in Example 37 1 H NMR spectrum. DETAILED DESCRIPTION

[0040] To make the technical problems, technical solutions, and effects of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0041] Example 1

[0042] ;

[0043] Under nitrogen atmosphere and room temperature, p-chloronitrobenzene (70 mg, 0.4443 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (57.6 mg, 0.3554 mmol, 0.8 eq), and trimethylsilyl chloride (242 mg, 2.2215 mmol, 5 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 h. After the reaction was completed, the mixture was extracted with dichloromethane and sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product (40 mg, yield 70.6%) was purified by silica gel column chromatography. Figure 1 shown.

[0044] 1 H NMR (400 MHz, Chloroform-d ) δ 7.02 (d, J = 8.8 Hz, 2H), 6.52 (d, J =8.8 Hz, 2H), 3.56 (s, 2H).

[0045] 13 C NMR (101 MHz, Chloroform- d ) δ 144.99, 129.14, 123.13, 116.26.

[0046] Example 2

[0047] ;

[0048] Under nitrogen atmosphere and room temperature, 3,5-dichloronitrobenzene (70 mg, 0.3645 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (47.3 mg, 0.2917 mmol, 0.8 eq), and trimethylsilyl chloride (29 mg, 0.3645 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 36 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 47 mg (yield 80%) was purified by silica gel column chromatography.

[0049] 1 H NMR (400 MHz, Chloroform- d ) δ 6.65 (t, J = 1.8 Hz, 1H), 6.46 (d, J =1.8 Hz, 2H), 3.89 – 3.56 (m, 2H).

[0050] 13 C NMR (101 MHz, Chloroform- d ) δ 148.23, 135.42, 118.35, 113.21.

[0051] Example 3

[0052] ;

[0053] Under nitrogen atmosphere and room temperature, 2,3,4,-trichloronitrobenzene (70 mg, 0.3091 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (40 mg, 0.2473 mmol, 0.8 eq), and trimethylsilyl chloride (34 mg, 0.3091 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 42 mg of the reduced product (yield 70%).

[0054] 1 H NMR (400 MHz, Chloroform- d ) δ 7.07 (d, J = 8.8 Hz, 1H), 6.54 (d, J =8.8 Hz, 1H), 4.11 (s, 2H).

[0055] 13 C NMR (101 MHz, Chloroform- d ) δ 142.02, 130.39, 127.21, 120.84,117.52, 112.78.

[0056] Example 4

[0057] ;

[0058] Under nitrogen atmosphere and room temperature, 2,3,4,5-tetrachloronitrobenzene (70 mg, 0.2683 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (34.8 mg, 0.2146 mmol, 0.8 eq), and trimethylsilyl chloride (29 mg, 0.2683 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 60 mg of the reduced product (yield 96.7%). Figure 2 shown.

[0059] 1 H NMR (400 MHz, Chloroform- d ) δ 6.74 (s, 1H), 4.18 (s, 2H).

[0060] 13 C NMR (101 MHz, Chloroform- d ) δ 142.84, 132.91, 132.13, 120.65,117.32, 114.13..

[0061] Example 5

[0062] ;

[0063] Under nitrogen atmosphere and room temperature, pentachloronitrobenzene (70 mg, 0.2370 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (30.7 mg, 0.1896 mmol, 0.8 eq), and trimethylsilyl chloride (25.7 mg, 0.2370 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, extraction was performed with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. Purification by silica gel column chromatography gave 55 mg of the reduced product (yield 83%). Figure 3 shown.

[0064] 1 H NMR (800 MHz, DMSO- d 6) δ 6.32 (s, 2H).

[0065] 13 C NMR (201 MHz, DMSO- d 6) δ 143.06, 130.51, 117.32, 115.99.

[0066] Example 6

[0067] ;

[0068] Under nitrogen atmosphere and room temperature, 4-bromonitrobenzene (70 mg, 0.3465 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (45 mg, 0.2772 mmol, 0.8 eq), and trimethylsilyl chloride (75 mg, 0.693 mmol, 2 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 40 mg of the reduced product (yield 67%).

[0069] 1 H NMR (400 MHz, Chloroform- d ) δ 7.20 – 7.12 (m, 2H), 6.55 – 6.45 (m,2H), 3.80 – 3.35 (m, 2H)

[0070] 13 C NMR (101 MHz, Chloroform- d ) δ 145.44, 132.03, 129.14, 116.74,116.25, 110.21.

[0071] Example 7

[0072] ;

[0073] Under nitrogen atmosphere and room temperature, 2,5-dibromonitrobenzene (70 mg, 0.2492 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (32 mg, 0.1994 mmol, 0.8 eq), and trimethylsilyl chloride (27 mg, 0.2492 mol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 45 mg of the reduced product (yield 72%).

[0074] 1 H NMR (400 MHz, Chloroform- d ) δ 7.20 – 6.97 (m, 1H), 6.85 – 6.47 (m, 2H), 4.05 (s, 2H).

[0075] 13 C NMR (101 MHz, Chloroform- d ) δ 145.29, 133.63, 130.51, 122.17,118.12, 107.77.

[0076] Example 8

[0077] ;

[0078] Under nitrogen atmosphere and room temperature, 4-nitrotrifluorotoluene (70 mg, 0.2683 mmol, 1 eq), V (MeCN): V (H2O) = 200: 1 (10 mL), ferric chloride (49.7 mg, 0.2146 mmol, 0.8 eq), and trimethylsilyl chloride (58.3 mg, 0.5366 mol, 2 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 8 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 34 mg of the reduced product (yield 59%). Figure 5 shown.

[0079] 1 H NMR (800 MHz, Chloroform- d ) δ 7.32 (d, J = 8.4 Hz, 2H), 6.62 (d, J =8.4 Hz, 2H), 3.87 (s, 2H).

[0080] 13 C NMR (201 MHz, Chloroform- d ) δ 148.30, 136.89, 125.68, 119.25,113.14.

[0081] 19 F NMR (753 MHz, Chloroform- d ) δ -61.24.

[0082] Example 9

[0083] ;

[0084] Under nitrogen atmosphere and room temperature, 3,5-ditrifluoromethylnitrobenzene (70 mg, 0.2702 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (35 mg, 0.2162 mmol, 0.8 eq), and trimethylsilyl chloride (147 mg, 1.351 mmol, 5 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 hours. After the reaction was completed, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 32 mg of the reduced product (yield 51.7%). Figure 5 shown.

[0085] 1 H NMR (400 MHz, Chloroform- d ) δ 7.19 (d, J = 4.9 Hz, 1H), 6.96 (s, 2H), 4.00 (s, 2H).

[0086] 13 C NMR (101 MHz, Chloroform- d ) δ 147.33, 132.69, 132.69, 114.18,111.56.

[0087] 19 F NMR (376 MHz, Chloroform- d ) δ -63.25.

[0088] Example 10

[0089] ;

[0090] Under nitrogen atmosphere and room temperature, 4-chloro-3-nitrobenzotrifluoride (70 mg, 0.3104 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (40 mg, 0.2483 mmol, 0.8 eq), and trimethylsilyl chloride (34 mg, 0.3104 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, extraction was carried out with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 40 mg of the reduced product (yield 66%).

[0091] 1 H NMR (400 MHz, Chloroform- d ) δ 7.26 – 7.21 (m, 1H), 6.90 – 6.80 (m, 2H), 4.13 (s, 2H).

[0092] 13 C NMR (101 MHz, Chloroform- d ) δ 143.24, 143.24, 129.84, 125.19,122.48, 115.31, 112.20.

[0093] 19 F NMR (376 MHz, Chloroform-d ) δ -62.82.

[0094] Example 11

[0095] ;

[0096] Under nitrogen atmosphere and room temperature, 2,4-dichloro-5-nitrotrifluoromethylbenzene (70 mg, 0.2692 mmol, 1 eq), V (MeCN): V (H2O) = 200: 1 (10 mL), ferric chloride (34.9 mg, 0.2154 mmol, 0.8 eq), and trimethylsilyl chloride (29.2 mg, 0.2692 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, extraction was performed with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 58 mg of the reduced product (yield 93%). Figure 11 shown.

[0097] 1 H NMR (400 MHz, Chloroform- d ) δ 7.30 (s, 1H), 6.97 (s, 1H), 4.17 (s, 2H).

[0098] 13 C NMR (101 MHz, Chloroform- d ) δ 140.71, 130.58, 122.85, 121.26,120.13, 118.92, 112.90.

[0099] 19 F NMR (376 MHz, Chloroform- d ) δ -62.60.

[0100] Example 12

[0101] ;

[0102] Under nitrogen atmosphere and room temperature, 2-nitrobenzonitrile (70 mg, 0.4726 mmol, 1 eq), V (MeCN): V (H2O) = 200:1 (10 mL), ferric chloride (61.3 mg, 0.3781 mmol, 0.8 eq), and trimethylsilyl chloride (51.3 mg, 0.4726 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After the reaction was completed, the mixture was extracted with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 43 mg of the reduced product (yield 77%). Figure 7 shown.

[0103] 1 H NMR (400 MHz, Chloroform- d ) δ 7.34 – 7.21 (m, 2H), 6.71 – 6.61 (m,2H), 4.36 (s, 2H).

[0104] 13 C NMR (101 MHz, Chloroform- d ) δ 148.63, 133.01, 131.32, 116.94,116.66, 114.14, 94.90.

[0105] Example 13

[0106] ;

[0107] Under nitrogen atmosphere and room temperature, 3-chloro-2-nitrobenzonitrile (70 mg, 0.3834 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (49.7 mg, 0.3067 mmol, 0.8 eq), and trimethylsilyl chloride (42 mg, 0.3834 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 hours. After the reaction was completed, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 36 mg of the reduced product (yield 63%). Figure 8 shown.

[0108] 1 H NMR (800 MHz, Chloroform- d ) δ 7.36 (dd, J = 7.9, 1.4 Hz, 1H), 7.26(dd, J= 7.8, 1.4 Hz, 1H), 6.62 (t, J = 7.9 Hz, 1H), 4.76 (s, 2H).

[0109] 13 C NMR (201 MHz, Chloroform- d ) δ 145.06, 132.92, 129.95, 118.48,117.01, 96.11.

[0110] Example 14

[0111] ;

[0112] Under nitrogen atmosphere and room temperature, 3-fluoro-2-nitrobenzonitrile (70 mg, 0.4214 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (54.6 mg, 0.3371 mmol, 0.8 eq), and trimethylsilyl chloride (45.7 mg, 0.4214 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 24 hours. After the reaction was completed, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 43 mg of the reduced product (yield 73%). Figure 9 shown.

[0113] 1 H NMR (800 MHz, Chloroform- d ) δ 7.13 – 7.07 (m, 2H), 6.61 (td, J =8.0, 4.8 Hz, 1H), 4.42 (s, 2H).

[0114] 13 C NMR (201 MHz, Chloroform- d ) δ 150.24, 137.96, 126.63, 118.40,116.62, 115.41, 96.84.

[0115] Example 15

[0116] ;

[0117] Under nitrogen atmosphere and room temperature, 2,6-difluoro-3-nitrobenzonitrile (70 mg, 0.3802 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (49.3 mg, 0.3041 mmol, 0.8 eq), and trimethylsilyl chloride (41.3 mg, 0.3802 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 36 hours. After the reaction was completed, the mixture was extracted with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. Purification by silica gel chromatography gave 45 mg of the reduced product (yield 76.8%). Figure 10 shown.

[0118] 1 H NMR (400 MHz, Chloroform- d ) δ 6.91 (td, J = 9.3, 5.5 Hz, 1H), 6.78(ddd, J = 9.1, 8.1, 1.6 Hz, 1H), 3.75 (s, 2H).

[0119] 13 C NMR (101 MHz, Chloroform- d ) δ 156.36, 149.22, 131.60, 121.39,111.95, 111.91, 109.76.

[0120] 19 F NMR (376 MHz, Chloroform- d ) δ -119.16, -125.80.

[0121] Example 16

[0122] ;

[0123] Under nitrogen atmosphere and room temperature, 4-chloro-3-nitrobenzophenone (70 mg, 0.2675 mmol, 1 eq), V (MeCN): V (H2O) = 200: 1 (10 mL), ferric chloride (34.7 mg, 0.2140 mmol, 0.8 eq), and trimethylsilyl chloride (29 mg, 0.2675 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After the reaction was completed, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel chromatography gave 38 mg of the reduced product (yield 62%). Figure 11 shown.

[0124] 1 H NMR (800 MHz, Chloroform- d ) δ 7.69 (dd, J = 8.2, 1.2 Hz, 2H), 7.51 –7.48 (m, 1H), 7.41 – 7.37 (m, 2H), 7.25 (d, J = 8.2 Hz, 1H), 7.14 (d, J = 2.0 Hz,1H), 6.99 (dd, J = 8.2, 2.0 Hz, 1H), 4.15 (s, 2H).

[0125] 13 C NMR (201 MHz, Chloroform- d ) δ 194.97, 141.98, 136.43, 136.00,131.44, 128.91, 128.15, 127.25, 122.45, 119.67, 115.70.

[0126] Example 17

[0127] ;

[0128] Under nitrogen atmosphere and room temperature, 2-chloro-3-nitropyridine (70 mg, 0.4415 mmol, 1 eq), acetonitrile (10 mL), ferric chloride (28 mg, 0.1766 mmol, 0.4 eq) and trimethylsilyl chloride (96 mg, 0.8830 mmol, 2 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 18 hours. After the reaction was completed, the mixture was extracted with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 30 mg (54%) of the reduced product. Figure 12 shown.

[0129] 1 H NMR (400 MHz, Chloroform- d ) δ 7.71 (t, J = 3.1 Hz, 1H), 6.97 (d, J =3.1 Hz, 2H), 4.08 (s, 2H).

[0130] 13 C NMR (101 MHz, Chloroform- d ) δ 139.72, 138.58, 136.92, 123.40,122.45.

[0131] Example 18

[0132] ;

[0133] Under nitrogen atmosphere and room temperature, 3-chloro-2-nitropyridine (70 mg, 0.4415 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (57 mg, 0.3532 mmol, 0.8 eq) and trimethylsilyl chloride (96 mg, 0.8830 mmol, 2 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 18 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 30 mg (53%) was purified by silica gel column chromatography.

[0134] 1 H NMR (400 MHz, Chloroform- d ) δ 7.91 (d, J = 4.9 Hz, 1H), 7.42 (d, J =7.7 Hz, 1H), 6.56 (dd,J = 7.7, 4.9 Hz, 1H), 5.01 – 4.71 (m, 2H).

[0135] 13 C NMR (101 MHz, Chloroform- d ) δ 139.72, 138.58, 136.92, 123.40,122.45.

[0136] Example 19

[0137] ;

[0138] Under nitrogen atmosphere and room temperature, 2-chloro-4-nitropyridine (70 mg, 0.4415 mmol, 1 eq), V(MeCN):V(H2O) (10 mL), ferric chloride (57 mg, 0.3532 mmol, 0.8 eq), and trimethylsilyl chloride (47.9 mg, 0.4415 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 29 mg (53%) of the reduced product. Figure 13 shown.

[0139] 1 H NMR (400 MHz, Chloroform- d ) δ 7.91 (d, J = 5.7 Hz, 1H), 6.48 (d, J =2.1 Hz, 1H), 6.37 (dd, J = 5.7, 2.1 Hz, 1H), 4.23 (s, 2H).

[0140] 13 C NMR (101 MHz, Chloroform- d ) δ 154.70, 152.25, 149.77, 108.87,108.55.

[0141] Example 20

[0142] ;

[0143] Under nitrogen atmosphere and room temperature, 2,6-dichloro-4-nitropyridine (70 mg, 0.3627 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (47 mg, 0.2902 mmol, 0.8 eq), and trimethylsilyl chloride (40 mg, 0.3627 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, extraction was carried out with dichloromethane and saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 48 mg of the reduced product (yield 82%).

[0144] 1 H NMR (800 MHz, DMSO- d 6) δ 6.77 (s, 2H), 6.50 (s, 2H).

[0145] Example 21

[0146] ;

[0147] Under nitrogen atmosphere and room temperature, 2,4-dichloro-5-nitropyridine (70 mg, 0.3627 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (47 mg, 0.2902 mmol, 0.8 eq), and trimethylsilyl chloride (40 mg, 0.3627 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 39 mg (65%) was purified by silica gel column chromatography.

[0148] 1 H NMR (400 MHz, DMSO- d 6) δ 7.88 (s, 1H), 7.44 (s, 1H), 5.83 (s, 2H).

[0149] 13 C NMR (101 MHz, DMSO- d 6) δ 141.96, 136.34, 136.26, 127.64, 123.79.

[0150] Example 22

[0151] ;

[0152] Under nitrogen atmosphere and room temperature, 2,5-dichloro-3-nitropyridine (70 mg, 0.3627 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (47 mg, 0.2902 mmol, 0.8 eq), and trimethylsilyl chloride (39.4 mg, 0.3627 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 37 mg (62%) was purified by silica gel column chromatography.

[0153] 1 H NMR (800 MHz, DMSO- d 6) δ 7.20 (s, 2H), 5.78 (s, 2H).

[0154] 13 C NMR (201 MHz, DMSO- d 6) δ 141.62, 133.85, 132.86, 125.70, 124.35.

[0155] Example 23

[0156] ;

[0157] Under nitrogen atmosphere and room temperature, 2,5-dichloro-3-nitropyridine (70 mg, 0.3627 mmol, 1 eq), acetonitrile (10 mL), ferric chloride (47.06 mg, 0.2902 mmol, 0.8 eq), and trimethylsilyl chloride (39.4 mg, 0.3627 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 43 mg (73%) was purified by silica gel column chromatography.

[0158] 1 H NMR (400 MHz, Chloroform- d ) δ 7.67 (d, J = 2.2 Hz, 1H), 6.96 (d, J =2.2 Hz, 1H), 4.16 (s, 2H).

[0159] 13 C NMR (101 MHz, Chloroform-d ) δ 139.15, 135.64, 133.69, 130.24,120.50.

[0160] Example 24

[0161] ;

[0162] Under nitrogen atmosphere and room temperature, 6-chloro-2-methyl-3-nitropyridine (70 mg, 0.4056 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (52.6 mg, 0.3245 mmol, 0.8 eq), and trimethylsilyl chloride (44 mg, 0.4056 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 36 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 42 mg (yield 73%) was purified by silica gel column chromatography.

[0163] 1 H NMR (800 MHz, Chloroform- d ) δ 6.90 (d, J = 8.3 Hz, 1H), 6.83 (d, J =8.3 Hz, 1H), 3.57 (s, 2H), 2.30 (s, 3H).

[0164] 13 C NMR (201 MHz, Chloroform- d ) δ 143.69, 139.47, 124.27, 121.99,20.02.

[0165] Example 25

[0166] ;

[0167] Under nitrogen atmosphere and room temperature, 2-chloro-4-methyl-3-nitropyridine (70 mg, 0.4056 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (52.6 mg, 0.3245 mmol, 0.8 eq), and trimethylsilyl chloride (44 mg, 0.4056 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm and stirred for 36 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 46 mg (yield 81%) was purified by silica gel column chromatography.

[0168] 1 H NMR (800 MHz, Chloroform- d ) δ 7.63 (s, 1H), 6.85 (s, 1H), 3.97 (s, 2H), 2.13 (s, 3H).

[0169] 13 C NMR (201 MHz, Chloroform- d ) δ 137.15, 137.05, 135.73, 130.79,123.72, 16.41.

[0170] Example 26

[0171] ;

[0172] Under nitrogen atmosphere and room temperature, 2,3,6-trichloro-5-nitropyridine (70 mg, 0.3078 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (33 mg, 0.2463 mmol, 0.8 eq), and trimethylsilyl chloride (33.4 mg, 0.3078 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 59 mg (98%) was purified by silica gel column chromatography.

[0173] 1 H NMR (400 MHz, DMSO- d 6) δ 7.15 (s, 1H), 5.87 (s, 2H).

[0174] 13 C NMR (101 MHz, DMSO- d6) δ 142.77, 131.30, 130.57, 128.65, 123.97.

[0175] Example 27

[0176] ;

[0177] Under nitrogen atmosphere and room temperature, 5-bromo-2-nitropyridine (70 mg, 0.3448 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (44.7 mg, 0.2759 mmol, 0.8 eq), and trimethylsilyl chloride (37 mg, 0.3448 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 39 mg of the reduced product (yield 65%).

[0178] 1 H NMR (400 MHz, DMSO- d 6) δ 7.81 (ddd, J = 25.7, 2.6, 0.6 Hz, 1H), 7.35(ddd, J = 35.7, 8.8, 2.7 Hz, 1H), 6.34 (ddd, J = 13.0, 8.8, 0.6 Hz, 1H), 6.05 (d, J = 6.9 Hz, 2H).

[0179] 13 C NMR (101 MHz, DMSO- d 6) δ 159.13, 148.33, 139.67, 110.46, 105.51.

[0180] Example 28

[0181] ;

[0182] Under nitrogen atmosphere and room temperature, 3-bromo-2-nitropyridine (70 mg, 0.3448 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (44.7 mg, 0.2759 mmol, 0.8 eq), and trimethylsilyl chloride (37 mg, 0.3448 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, extraction was carried out with dichloromethane and saturated sodium bicarbonate aqueous solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 30 mg of the reduced product (yield 50%).

[0183] 1 H NMR (400 MHz, Chloroform- d ) δ 7.92 (ddd, J = 14.2, 4.9, 1.5 Hz, 1H),7.49 (ddd, J = 64.5, 7.7, 1.5 Hz, 1H), 6.66 – 6.37 (m, 1H), 4.99 (s, 2H).

[0184] 13 C NMR (101 MHz, Chloroform- d ) δ 154.57, 145.94, 139.32, 103.42.

[0185] Example 29

[0186] ;

[0187] Under nitrogen atmosphere and room temperature, 5-bromo-2-chloro-3-nitropyridine (70 mg, 0.2948 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (38.3 mg, 0.2358 mmol, 0.8 eq), and trimethylsilyl chloride (32 mg, 0.2948 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, extraction was carried out with dichloromethane and saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 40 mg of the reduced product (yield 65%).

[0188] 1 H NMR (400 MHz, DMSO- d 6) δ 7.46 (d, J= 2.2 Hz, 1H), 7.10 (d, J = 2.2 Hz,1H), 5.72 (s, 2H).

[0189] 13 C NMR (101 MHz, DMSO- d 6) δ 143.34, 136.02, 134.15, 123.53, 119.58.

[0190] Example 30

[0191] ;

[0192] Under nitrogen atmosphere and room temperature, 2-bromo-5-nitropyrimidine (70 mg, 0.3432 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (45 mg, 0.2745 mmol, 0.8 eq), and trimethylsilyl chloride (74.6 mg, 0.6864 mmol, 2 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 36 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 50 mg (yield 83%) was purified by silica gel column chromatography.

[0193] 1 H NMR (800 MHz, Chloroform- d ) δ 8.03 (s, 2H), 3.72 (s, 2H).

[0194] 13 C NMR (201 MHz, Chloroform- d ) δ 149.28, 144.34, 138.34.

[0195] Example 31

[0196] ;

[0197] Under nitrogen atmosphere and room temperature, 4,6-dichloro-5-nitropyrimidine (70 mg, 0.3609 mmol, 1 eq), V(MeCN):V(H2O)=5:1 (10 mL), and ferric chloride (46.83 mg, 0.2887 mmol, 0.8 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After the reaction was completed, the mixture was extracted with dichloromethane and water, the organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 53 mg of the reduced product (yield 90%). Figure 14 shown.

[0198] 1 H NMR (400 MHz, Chloroform- d ) δ 8.13 (s, 1H), 4.50 (s, 2H).

[0199] 13 C NMR (101 MHz, Chloroform- d ) δ 145.95, 144.20, 135.95.

[0200] Example 32

[0201] ;

[0202] Under nitrogen atmosphere and room temperature, 2,4-dichloro-5-nitropyrimidine (70 mg, 0.3609 mmol, 1 eq), V(MeCN):V(H2O)=5:1 (10 mL), and ferric chloride (46.83 mg, 0.2887 mmol, 0.8 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and water. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 54 mg (yield 92%) was purified by silica gel column chromatography.

[0203] 1 H NMR (400 MHz, Chloroform- d ) δ 8.02 (s, 1H), 4.48 – 3.81 (m, 2H).

[0204] 13 C NMR (101 MHz, Chloroform- d ) δ 146.02, 144.41, 137.24.

[0205] Example 33

[0206] ;

[0207] Under nitrogen atmosphere and room temperature, 5-nitro-2,4,6-trichloropyrimidine (70 mg, 0.3065 mmol, 1 eq), V(MeCN):V(H2O) (5:1) (10 mL), and ferric chloride (40 mg, 0.2452 mmol, 0.8 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 24 hours. After completion of the reaction, the mixture was extracted with dichloromethane and water, and the organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 51 mg (yield 84%) was purified by silica gel column chromatography.

[0208] 1 H NMR (400 MHz, Chloroform- d ) δ 4.47 (s, 2H).

[0209] 13 C NMR (101 MHz, Chloroform- d ) δ 145.24, 145.10, 134.78.

[0210] Example 34

[0211] ;

[0212] Under nitrogen atmosphere and room temperature, 2-methyl-4,6-dichloro-5-nitropyrimidine (70 mg, 0.3365 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (43.7 mg, 0.2692 mmol, 0.8 eq), and trimethylsilyl chloride (37 mg, 0.3365 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 35 mg of the reduced product (yield 58%).

[0213] 1 H NMR (400 MHz, Chloroform- d ) δ 4.29 (s, 2H), 2.50 (s, 3H).

[0214] 13 C NMR (101 MHz, Chloroform- d ) δ 155.00, 143.33, 131.95, 23.31.

[0215] Example 35

[0216] ;

[0217] Under nitrogen atmosphere and room temperature, 2,4-dichloro-5-nitro-6-methylpyrimidine (70 mg, 0.3365 mmol, 1 eq), V(MeCN):V(H2O)=5:1 (10 mL), ferric chloride (44 mg, 0.2692 mmol, 0.8 eq), and trimethylsilyl chloride (37 mg, 0.3365 mmol, 1 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and water. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. The reduced product 47 mg (yield 78%) was purified by silica gel column chromatography.

[0218] 1 H NMR (800 MHz, Chloroform- d ) δ 4.03 (s, 2H), 2.38 (s, 3H).

[0219] 13 C NMR (201 MHz, Chloroform- d ) δ 153.30, 145.78, 143.79, 134.12,19.32.

[0220] Example 36

[0221] ;

[0222] Under nitrogen atmosphere and room temperature, ethyl 2,6-dichloro-5-nitropyrimidine-4-carboxylate (70 mg, 0.2631 mmol, 1 eq), V(MeCN):V(H2O)=5:1 (10 mL), ferric chloride (34 mg, 0.2105 mmol, 0.8 eq), and trimethylsilyl chloride (29 mg, 0.2631 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 8 hours. After the reaction was completed, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 60 mg of the reduced product (yield 96.7%). Figure 15 shown.

[0223] 1 H NMR (400 MHz, Chloroform- d ) δ 6.16 (s, 2H), 4.41 (q,J = 7.1 Hz,2H), 1.38 (t, J = 7.1 Hz, 3H).

[0224] 13 C NMR (101 MHz, Chloroform- d ) δ 165.42, 150.78 – 150.60 (m), 144.51,139.53, 133.82, 62.82, 14.21.

[0225] Example 37

[0226] ;

[0227] Under nitrogen atmosphere and room temperature, 2-chloro-5-nitropyrazine (70 mg, 0.4388 mmol, 1 eq), V (MeCN): V (H2O) = 200: 1 (10 mL), ferric chloride (57 mg, 0.3510 mmol, 0.8 eq), and trimethylsilyl chloride (48 mg, 0.4388 mmol, 1 eq) were added to a 25 mL quartz test tube, irradiated with 395 nm light and stirred for 48 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then distilled under reduced pressure. Purification by silica gel column chromatography gave 41 mg of the reduced product (yield 95%). Figure 16 shown.

[0228] 1 H NMR (800 MHz, DMSO- d 6) δ 7.99 (s, 1H), 7.68 (s, 1H), 6.64 (s, 2H).

[0229] 13 C NMR (201 MHz, DMSO- d 6) δ 155.60, 141.26, 134.18, 131.46.

[0230] Example 38

[0231] ;

[0232] Under nitrogen atmosphere and room temperature, 2-bromo-5-nitropyrazine (70 mg, 0.3432 mmol, 1 eq), V(MeCN):V(H2O)=200:1 (10 mL), ferric chloride (45 mg, 0.2745 mmol, 0.8 eq), and trimethylsilyl chloride (74.6 mg, 0.6864 mmol, 2 eq) were added to a 25 mL quartz test tube. The mixture was irradiated with 395 nm light and stirred for 36 hours. After completion of the reaction, the mixture was extracted with dichloromethane and a saturated aqueous sodium bicarbonate solution. The organic layers were combined, dried over anhydrous sodium sulfate, and then evaporated under reduced pressure. The reduced product 54 mg (yield 90%) was purified by silica gel column chromatography.

[0233] 1 H NMR (800 MHz, DMSO- d 6) δ 7.99 (s, 1H), 7.68 (s, 1H), 6.64 (s, 2H).

[0234] 13 C NMR (201 MHz, DMSO- d 6) δ 155.60, 141.26, 134.18, 131.46.

[0235] Example 39

[0236] Same as Example 11, except that the light wavelength is 365 nm and the reduction product yield is 57%.

[0237] Example 40

[0238] Same as Example 11, except that the light wavelength is 455 nm and the reduction product yield is 42%.

[0239] Example 41

[0240] Same as Example 11, except that the solvent was MeCN, and the yield of the reduction product was 72%.

[0241] Example 42

[0242] Same as Example 11, except that the solvent was V(MeCN):V(H2O)=10:1, and the yield of the reduction product was 55%.

[0243] Example 43

[0244] Same as Example 11, except that the solvent was V(MeCN):V(H2O)=5:1, and the yield of the reduction product was 38%.

[0245] Example 44

[0246] Same as Example 11, except that the solvent was V(MeCN):V(H2O)=2:1, and the yield of the reduction product was 45%.

[0247] Example 45

[0248] Same as Example 11, except that the solvent was dichloromethane, and the yield of the reduction product was 43%.

[0249] Example 46

[0250] Same as Example 11, except that the solvent was N,N-dimethylformamide, and the yield of the reduction product was 75%.

[0251] Example 47

[0252] Same as Example 11, except that the catalyst is ferrous chloride, and the reduction product yield is 48%.

[0253] Example 48

[0254] The same as Example 11, except that the amount of ferric chloride used was 0.2 eq, and the yield of the reduction product was 40%.

[0255] Example 49

[0256] The only difference from Example 11 is that the amount of ferric chloride used is 0.5 eq, and the reduction product yield is 52%.

[0257] Example 50

[0258] The only difference from Example 11 is that the amount of ferric chloride used is 1 eq, and the reduction product yield is 75%.

[0259] Example 51

[0260] The only difference from Example 11 is that the amount of ferric chloride used is 2 eq, and the reduction product yield is 72%.

[0261] Example 52

[0262] The only difference from Example 11 is that the amount of TMSCl used is 2 eq, and the yield of the reduction product is 53%.

[0263] Example 53

[0264] The only difference from Example 11 is that the amount of TMSCl used is 4 eq, and the yield of the reduction product is 50%.

[0265] Example 54

[0266] Same as Example 11, except that the additive is tetrabutylammonium chloride, and the yield of the reduction product is 56%.

[0267] Example 55

[0268] Same as Example 11, except that the additive was oxalyl chloride, and the yield of the reduction product was 45%.

[0269] Example 56

[0270] Same as Example 11, except that the additive was 37% hydrochloric acid, and the yield of the reduction product was 35%.

Claims

1. A method for photocatalytic reduction of nitro groups to amino groups using ferric chloride, characterized in that: The following steps are involved: At room temperature, the nitro compound represented by formula (1) is dissolved in a solvent, a catalyst and an additive are added, and a light-irradiated reaction is carried out to obtain an amino product represented by formula (2); ； Wherein, in formula (1) and formula (2), when X1, X2, X3 = C, a benzene ring is formed; R1, R2, R3 are one or more of cyano, halogenated alkyl, aryl, and halogen; R4 and R5 are one or more of hydrogen, halogen, and halogenated alkyl; When X1=N, X2, X3=C, a pyridine ring is formed; R2 and R5 are one or more of halogen and alkyl; R1 is one of hydrogen, halogen and alkyl, R3 is halogen, and R4 is hydrogen; When X1, X2 = N, X3 = C, a pyrimidine ring is formed, R1, R5 are one or more of halogen, alkyl, and ester groups; R3 is one of halogen and alkyl, and R2 and R4 are hydrogen; When X1, X3 = N, X2 = C, a pyrazine ring is formed, R3 is a halogen; R1, R2, R4, R5 are hydrogen; The solvent is dichloromethane, N,N-dimethylformamide, acetonitrile or an acetonitrile-water mixture with a volume ratio of 2:1-200:1; The catalyst is selected from one of ferrous chloride and ferric chloride; The additive is selected from one of hydrochloric acid, oxalyl chloride, trimethylchlorosilane and tetrabutylammonium chloride.

2. The method according to claim 1, characterized in that The alkyl group is a methyl group, the ester group is an ethyl formate group, the halogenated alkyl group is a trifluoromethyl group, and the halogen group is one or more of fluorine, chlorine, and bromine.

3. The method according to claim 1, characterized in that The wavelength range of the light for the illumination reaction is 365-455 nm.

4. The method according to claim 1, wherein The molar ratio of the nitro compound of formula (1) to the catalyst is 5:1 to 1:

2.

5. The method according to claim 1, wherein The molar ratio of the nitro compound of formula (1) to trimethylchlorosilane is 1:1 to 1:

4.

6. The method according to claim 1, characterized in that The light reaction time is 8 to 48 hours.

7. The method according to claim 1, characterized in that The atmosphere was nitrogen.

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