Synthesis method of an asymmetric azoxybenzene compound

Abstract

The present invention discloses a method for synthesizing an asymmetric azoxybenzene compound. Under light irradiation conditions, iminoiodobenzene and a nitroso compound are reacted in dichloromethane. First, iminoiodobenzene generates nitrene under light irradiation conditions, and then it is captured by the nitroso compound to generate an asymmetric azoxybenzene compound. This method is driven by visible light as a green energy source, without the addition of a catalyst, and the target product can be obtained by reacting for 2 h at room temperature. The reaction conditions are mild and rapid, and at the same time, it is insensitive to air and water and is easy to operate.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and particularly relates to a method for synthesizing an asymmetric azoxybenzene compound. Background Art

[0002] As an important organic synthesis intermediate and chemical raw material, azoxybenzene compounds have been applied in the fields of dyes, polymer materials, and biomedicine. Due to the wide application of azoxybenzene derivatives in various industries, their synthesis research has attracted the attention of scientific researchers. There are already many reported methods for synthesizing azoxybenzene compounds, and their preparation is generally divided into two approaches. One is to prepare by reducing aromatic nitro compounds with a reducing agent, and the other is to obtain by oxidizing aromatic amino compounds with an oxidizing agent. However, most methods have certain limitations, such as the need for transition metals and toxic catalysts, and harsh reaction conditions.

[0003]

[0004] At the same time, there are more reports in the literature on the synthesis of symmetric azoxybenzene compounds, while there are fewer reports on the synthesis of asymmetric azoxybenzene. When using traditional methods to synthesize asymmetric azoxybenzene, there are disadvantages such as harsh reaction conditions, complex synthesis steps, and difficult separation of products. In recent years, in order to introduce different functional groups into azo compounds, many strategies for synthesizing asymmetric azoxybenzene compounds through C-H bond activation functionalization have been developed, including ortho-alkoxylation, halogenation, alkoxylation, and alkenylation. This method has obvious defects. It is necessary to first synthesize symmetric azoxybenzene as a starting material, and only functional groups can be introduced at the ortho position. This limitation in the synthesis strategy leads to insufficient practicality of this method. Therefore, it is of great significance to develop a green, efficient, and simple method for synthesizing asymmetric azoxybenzene.

[0005]

[0006] In recent years, the method of metal-catalyzed nitrene transfer reaction under ultraviolet light irradiation has attracted the interest of synthetic chemists. However, since ultraviolet light must be used to generate the key nitrene intermediate, which can easily affect the reaction efficiency and cause harmful side reactions, it is highly desirable to use visible light instead of ultraviolet light to reduce unnecessary side reactions and achieve more sustainable reaction conditions. In 2020, the Koenigs research group reported a direct aziridination reaction of iminoiodanes and alkenes under photocatalytic conditions. This strategy obtains the nitrene radical anion by using iminoiodane to oxidize and quench the excited state of the photocatalyst, and then adds to the alkene, opening up the concept of photocatalytic nitrene transfer reaction through the nitrene radical anion, and opening up a way for efficient photocatalytic and metal-free amination reactions in modern nitrene chemistry.

[0007]

[0008] In 2022, the Koenigs research group also reported the use of nitrene transfer reaction under metal-free visible light chemical conditions for the synthesis of sulfimines. At the same time, the reaction protocol was further extended to a sulfonylation / rearrangement cascade reaction for the synthesis of sulfonamides.

[0009] Summary of the Invention

[0010] Through research, our research group found that under the irradiation of a blue LED lamp, iminoiodobenzene will photolyze to generate nitrene, which is then captured by a nitroso compound to produce the target product - asymmetric azoxybenzene.

[0011] The reaction process is specifically described as follows:

[0012] First, under blue light irradiation, the nitrene precursor iminoiodobenzene will photolyze, eliminating a molecule of iodobenzene to generate a free active intermediate nitrene, which will be quickly captured by a nitroso compound to undergo a nitrene transfer reaction, ultimately obtaining an asymmetric azoxybenzene compound.

[0013]

[0014] Based on the above research background, the present invention provides a synthesis method for obtaining asymmetric azoxybenzene derivatives through a nitrene transfer reaction. The present invention uses iminoiodobenzene as a nitrene precursor, generates a nitrene intermediate under light irradiation, and is then captured by a nitroso compound to obtain the target product - asymmetric azoxybenzene. This method is driven by visible light as a green energy source, does not require the addition of a catalyst, and can obtain the final product in good to excellent yields after reacting at room temperature for 2 h. The reaction conditions are mild and easy to operate.

[0015] Synthesis method of the asymmetric azoxybenzene compound of the present invention: Dissolve the nitroso compound 1 and the iodoarylimine compound 2 in the solvent dichloromethane, place them in a 24W blue LED lamp box, turn on the light and the fan, and react and stir for 2 hours. After separation and purification, the target product 3 is obtained.

[0016] The synthesis route is as follows:

[0017]

[0018] The substituent R in the nitroso compound 1 1 is selected from alkyl, aryl, and heteroaryl.

[0019] The substituent R in the iodoarylimine compound 2 2 is selected from benzenesulfonyl groups substituted by alkyl, halogen, or nitro at the ortho position, benzenesulfonyl groups substituted by nitro at the meta position, and benzenesulfonyl groups substituted by hydrogen, alkyl, or halogen at the para position.

[0020] The separation and purification is carried out by means of silica gel column chromatography, and the eluent is petroleum ether and ethyl acetate, with a volume ratio of 10:1 - 3:1.

[0021] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0022] 1. There is no need to add a catalyst, with low cost, no toxicity, and easy operation.

[0023] 2. Illumination is carried out with an ordinary blue LED lamp.

[0024] 3. The reaction is carried out at room temperature, insensitive to air and water, and the reaction conditions are mild.

[0025] 4. The reaction time is rapid and the reaction efficiency is high.

[0026] 5. The target product can be used as an intermediate to further react with oxocyclic compounds to obtain nitrogen-carbon insertion or unsaturated bond difunctionalized products. Specific embodiments

[0027] The technical solution of the present invention will be further described in detail below in combination with specific embodiments.

[0028] Example 1:

[0029]

[0030] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodobenzene imine 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a yellow solid, is obtained with a yield of 92%.

[0031] Compound 3aa was tested as follows:

[0032] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.21–8.14 (m, 2H), 8.08–8.02 (m, 2H), 7.68–7.62 (m, 1H), 7.52–7.46 (m, 2H), 7.37 (d, J = 7.8 Hz, 2H), 2.45 (s, 3H).

[0033] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.4, 145.7, 134.4, 133.2, 130.1, 129.5, 129.3, 122.8, 21.8.

[0034] Example 2:

[0035]

[0036] In a 10 mL reaction flask, add nitroso compound 1b (0.1 mmol, 18.3 mg), iodobenzene imine 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a yellow solid, is obtained with a yield of 80%.

[0037] Compound 3ba was tested as follows:

[0038] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.27–8.22 (m, 2H), 8.09–8.04 (m, 2H), 7.70–7.66 (m, 2H), 7.61–7.58 (m, 2H), 7.51–7.40 (m, 3H), 7.38 (d, J = 8.1 Hz, 2H), 2.46 (s, 3H).

[0039] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 147.6, 145.8, 145.3, 138.7, 133.3, 130.1, 129.5, 129.1, 128.9, 127.7, 127.3, 123.4, 21.8.

[0040] Example 3:

[0041]

[0042] In a 10 mL reaction flask, add nitroso compound 1c (0.1 mmol, 14.1 mg), iodosobenzene imine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, is obtained with a yield of 76%.

[0043] Compound 3ca was tested:

[0044] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.16–8.10 (m, 2H), 8.07–8.00 (m, 2H), 7.48–7.43 (m, 2H), 7.38 (d, J = 7.8 Hz, 2H), 2.46 (s, 3H).

[0045] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.1, 144.8, 141.2, 133.0, 130.2, 129.5, 124.2, 21.8.

[0046] Example 4:

[0047]

[0048] In a 10 mL reaction flask, add nitroso compound 1d (0.1 mmol, 18.6 mg), iodoaryl imine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, brown oil, is obtained with a yield of 78%.

[0049] Compound 3da was tested as follows:

[0050] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.10–7.98 (m, 4H), 7.62 (d, J = 9.0 Hz, 2H), 7.37 (d, J = 8.1 Hz, 2H), 2.46 (s, 3H).

[0051] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.1, 145.3, 133.0, 132.6, 130.2, 129.8, 129.6, 124.3, 21.8.

[0052] Example 5:

[0053]

[0054] In a 10 mL reaction flask, add nitroso compound 1e (0.1 mmol, 17.9 mg), iodoaryl imine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, is obtained with a yield of 86%.

[0055] Compound 3ea was tested as follows:

[0056] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.22 (d, J = 9.0 Hz, 2H), 8.14 (d, J = 8.9 Hz, 2H), 8.05 (d, J = 8.1 Hz, 2H), 7.38 (d, J = 8.0 Hz, 2H), 4.41 (q, J = 7.1 Hz, 2H), 2.46 (s, 3H), 1.41 (t, J = 7.1 Hz, 3H)

[0057] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.7, 149.0, 146.2, 135.7, 132.9, 130.5, 130.2, 129.6, 122.9, 61.9, 21.8, 14.2.

[0058] Example 6:

[0059]

[0060] In a 10 mL reaction flask, nitroso compound 1f (0.1 mmol, 14.1 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED light box, and the reaction was stirred under light and with a fan for 2 hours. Purification was carried out by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 was preferred], and a pure product, colorless oil, was obtained with a yield of 81%.

[0061] Compound 3fa was tested:

[0062] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.17 (t, J = 2.1 Hz, 1H), 8.09–8.01 (m, 3H), 7.64–7.60 (m, 1H), 7.47–7.35 (m, 3H), 2.46 (s, 3H).

[0063] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 147.1, 146.2, 135.4, 134.5, 132.9, 130.3, 130.2, 129.6, 123.2, 121.0, 21.8.

[0064] Example 7:

[0065]

[0066] In a 10 mL reaction flask, add 1 g (0.1 mmol, 12.1 mg) of the nitroso compound, 2a (0.15 mmol, 55.9 mg) of iodoarylimine, and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 80%.

[0067] Compound 3ga was tested as follows:

[0068] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.04 (d, J = 8.1 Hz, 2H), 7.68 (d, J = 8.0 Hz, 1H), 7.45–7.36 (m, 3H), 7.30–7.24 (m, 2H), 2.46 (s, 3H), 2.36 (s, 3H).

[0069] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 147.4, 145.9, 133.2, 132.6, 132.4, 132.2, 130.0, 129.5, 126.8, 124.1, 21.8, 18.9.

[0070] Example 8:

[0071]

[0072] In a 10 mL reaction flask, add 1h (0.1 mmol, 14.2 mg) of the nitroso compound, 2a (0.15 mmol, 55.9 mg) of iodoarylimine, and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a brown oil, is obtained with a yield of 95%.

[0073] Compound 3ha was tested as follows:

[0074] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.04 (d, J = 8.0 Hz, 2H), 7.64 (d, J = 8.0 Hz, 1H), 7.50–7.43 (m, 2H), 7.38 (d, J = 8.0 Hz, 3H), 2.47 (s, 3H).

[0075] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.2, 145.9, 132.6, 132.5, 131.4, 130.1, 129.6, 127.6, 127.0, 125.3, 21.8.

[0076] Example 9:

[0077]

[0078] In a 10 mL reaction flask, add nitroso compound 1i (0.1 mmol, 18.6 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product is obtained, which is a brown oil, yield: 86%.

[0079] Compound 3ia was tested:

[0080] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.07–8.01 (m, 2H), 7.65–7.57 (m, 2H), 7.43–7.34 (m, 4H), 2.46 (s, 3H).

[0081] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 147.6, 146.3, 134.5, 132.5, 130.2, 129.5, 128.3, 125.3, 114.8, 21.8.

[0082] Example 10:

[0083]

[0084] In a 10 mL reaction flask, add nitroso compound 1j (0.1 mmol, 23.3 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product is obtained, which is a yellow solid, yield: 85%.

[0085] Compound 3ja was tested:

[0086] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.07 (d, J = 8.1 Hz, 2H), 7.89 (d, J = 7.9 Hz, 1H), 7.59 (d, J = 8.1 Hz, 1H), 7.47–7.36 (m, 3H), 7.21 (t, J = 6.9 Hz, 1H), 2.47 (s, 3H).

[0087] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 150.9, 146.3, 141.1, 132.6, 132.5, 130.4, 129.5, 125.0, 86.8, 21.8.

[0088] Example 11:

[0089]

[0090] In a 10 mL reaction flask, nitroso compound 1k (0.1 mmol, 17.6 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED lamp box and irradiated with light and stirred with a fan for 2 hours. It was separated and purified by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, was obtained with a yield of 88%.

[0091] Compound 3ka was tested:

[0092] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.27 (d, J = 2.6 Hz, 1H), 8.01 (d, J = 8.5 Hz, 3H), 7.56 (d, J = 8.9 Hz, 1H), 7.36 (d, J = 8.1 Hz, 2H), 2.44 (s, 3H).

[0093] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.3, 145.0, 139.5, 133.9, 132.7, 131.0, 130.2, 129.6, 124.8, 121.9, 21.8..

[0094] Example 12:

[0095]

[0096] In a 10 mL reaction flask, nitroso compound 1l (0.1 mmol, 15.7 mg), iodoarylimine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED light box, and the reaction was stirred with light and a fan for 2 hours. It was separated and purified by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 was preferred], and a pure product, a yellow solid, was obtained with a yield of 94%.

[0097] Compound 3la was tested:

[0098] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.74 (d, J = 2.3 Hz, 1H), 8.21–8.13 (m, 1H), 8.08 (d, J = 8.3 Hz, 2H), 7.97–7.86 (m, 3H), 7.68–7.56 (m, 2H), 7.37 (d, J = 8.0 Hz, 2H), 2.45 (s, 3H).

[0099] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 145.9, 143.6, 135.8, 133.3, 132.0, 130.2, 129.9, 129.7, 129.5, 128.0, 127.9, 123.9, 118.7, 21.8.

[0100] Example 13:

[0101]

[0102] In a 10 mL reaction flask, nitroso compound 1m (0.1 mmol, 10.8 mg), iodoarylimine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED light box, and the reaction was stirred with light and a fan for 2 hours. It was separated and purified by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 was preferred], and a pure product, a colorless oil, was obtained with a yield of 88%.

[0103] Compound 3ma was tested:

[0104] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.64–8.58 (m, 1H), 8.22 (d, J = 8.2 Hz, 1H), 8.10–8.05 (m, 2H), 8.03–7.97 (m, 1H), 7.67–7.62 (m, 1H), 7.37 (d, J = 8.6 Hz, 2H), 2.45 (s, 3H).

[0105] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 155.9, 149.0, 146.2, 139.7, 132.6, 130.3, 129.5, 128.9, 117.7, 21.7.

[0106] Example 14:

[0107]

[0108] In a 10 mL reaction flask, add nitroso compound 1m (0.1 mmol, 8.7 mg), iodosobenzene imine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V (petroleum ether): V (ethyl acetate) = 10:1 - 3:1, in this example, V (petroleum ether): V (ethyl acetate) = 5:1 is preferred], and a pure product, a yellow solid, can be obtained. Yield: 14%.

[0109] Compound 3na was tested:

[0110] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 7.90 (d, J = 8.1 Hz, 2H), 7.31 (d, J = 8.0 Hz, 2H), 2.43 (s, 3H), 1.53 (s, 9H).

[0111] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 145.4, 133.2, 129.6, 129.4, 82.9, 28.0, 21.7. Example 15:

[0112]

[0113] In a 10 mL reaction flask, add nitroso compound 1o (0.1 mmol, 28.7 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Separate and purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a yellow solid, is obtained with a yield of 45%.

[0114] Compound 3oa was tested as follows:

[0115] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.22 (d, J = 8.9 Hz, 2H), 8.13 (d, J = 8.9 Hz, 2H), 8.04 (d, J = 8.3 Hz, 2H), 7.37 (d, J = 8.1 Hz, 2H), 5.16–5.07 (m, 1H), 2.45 (s, 4H), 2.08–1.98 (m, 1H), 1.87–1.72 (m, 2H), 1.47–1.36 (m, 1H), 1.33–1.25 (m, 1H), 1.13–1.07 (m, 1H), 0.95 (s, 3H), 0.90 (d, J = 5.2 Hz, 6H).

[0116] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.9, 148.9, 146.1, 136.0, 132.9, 130.5, 130.2, 129.6, 122.9, 81.8, 49.1, 48.0, 44.9, 36.8, 28.0, 27.4, 21.8, 19.7, 18.9, 13.6.

[0117] Example 16:

[0118]

[0119] In a 10 mL reaction flask, add nitroso compound 1o (0.1 mmol, 31.1 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Separate and purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a brown solid, is obtained with a yield of 85%.

[0120] Compound 3pa was tested as follows:

[0121] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.18–8.13 (m, 2H), 8.03–7.99 (m, 2H), 7.35 (d, J = 7.7 Hz, 2H), 7.27–7.23 (m, 2H), 7.15–7.09 (m, 4H), 3.96–3.88 (m, 1H), 2.47–2.43 (m, 5H), 1.90–1.78 (m, 1H), 1.59 (d, J = 7.1 Hz, 3H), 0.89 (d, J = 6.6 Hz, 6H).

[0122] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 172.3, 155.6, 145.9, 143.4, 141.2, 136.5, 133.1, 130.1, 129.7, 129.5, 127.1, 124.4, 122.3, 45.3, 45.0, 30.1, 22.4, 21.8, 18.3.

[0123] Example 17:

[0124]

[0125] In a 10 mL reaction flask, add nitroso compound 1q (0.1 mmol, 39.3 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, is obtained with a yield of 88%.

[0126] Compound 3qa was tested:

[0127] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.21 (d, J = 8.7 Hz, 2H), 8.13 (d, J = 8.6 Hz, 2H), 8.03 (d, J = 8.1 Hz, 2H), 7.37 (d, J = 8.0 Hz, 2H), 5.54 (d, J = 4.9 Hz, 1H), 4.67–4.61 (m, 1H), 4.56–4.42 (m, 2H), 4.36–4.27 (m, 2H), 4.19–4.12 (m, 1H), 2.45 (s, 3H), 1.47 (d, J = 9.8 Hz, 6H), 1.33 (d, J = 8.2 Hz, 6H).

[0128] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.6, 149.1, 146.2, 135.3, 132.9, 130.7, 130.2, 129.6, 122.9, 109.8, 108.8, 96.3, 71.1, 70.7, 70.4, 66.0, 64.8, 26.0, 25.9, 24.9, 24.5, 21.8. Example 18:

[0129]

[0130] In a 10 mL reaction flask, add nitroso compound 1r (0.1 mmol, 28.9 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, is obtained with a yield of 80%.

[0131] Compound 3ra was tested:

[0132] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.25–8.19 (m, 2H), 8.16–8.10 (m, 2H), 8.08–8.01 (m, 2H), 7.38 (d, J = 8.2 Hz, 2H), 5.00–4.90 (m, 1H), 2.46 (s, 3H), 2.16–2.05 (m, 1H), 1.94–1.83 (m, 1H), 1.77–1.69 (m, 2H), 1.61–1.52 (m, 2H), 1.19–1.07 (m, 2H), 0.94–0.90 (m, 6H), 0.78 (d, J = 7.0 Hz, 3H).

[0133] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.2, 148.9, 146.1, 136.0, 132.9, 130.5, 130.2, 129.6, 122.8, 76.1, 47.1, 40.8, 34.2, 31.4, 26.6, 23.6, 22.0, 21.8, 20.7, 16.5.

[0134] Example 19:

[0135]

[0136] In a 10 mL reaction flask, add nitroso compound 1s (0.1 mmol, 28.3 mg), iodosobenzene imine 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a yellow solid, is obtained with a yield of 87%.

[0137] Compound 3sa was tested:

[0138] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.11 (d, J = 8.9 Hz, 2H), 8.02 (d, J = 7.9 Hz, 2H), 7.34 (d, J = 8.0 Hz, 2H), 7.28–7.19 (m, 3H), 6.79 (d, J = 8.8 Hz, 2H), 2.87 (p, J = 6.8 Hz, 2H), 2.43 (s, 3H), 1.09 (d, J = 6.9 Hz, 12H).

[0139] 1313C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.3, 147.6, 145.6, 141.1, 139.9, 133.6, 130.1, 129.4, 126.8, 125.4, 124.8, 115.0, 27.0, 23.2, 21.8.

[0140] Example 20:

[0141]

[0142] In a 10 mL reaction flask, add nitroso compound 1t (0.1 mmol, 51.9 mg), iminoiodobenzene 2a (0.15 mmol, 55.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 46%.

[0143] Compound 3ta was tested:

[0144] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.22 (d, J = 8.9 Hz, 2H), 8.13 (d, J = 8.9 Hz, 2H), 8.05 (d, J = 8.1 Hz, 2H), 7.38 (d, J = 8.1 Hz, 2H), 5.42 (d, J = 5.0 Hz, 1H), 4.96–4.78 (m, 1H), 2.46 (s, 5H), 2.06–1.68 (m, 6H), 1.63–1.44 (m, 7H), 1.41–0.95 (m, 19H), 0.92 (d, J = 6.5 Hz, 3H), 0.88–0.84 (m, 6H), 0.69 (s, 3H).

[0145] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 164.1, 148.9, 146.1, 139.3, 136.1, 132.9, 130.6, 130.2, 129.6, 123.2, 122.8, 75.8, 56.7, 56.1, 50.0, 42.3, 39.7, 39.5, 38.1, 36.9, 36.6, 36.2, 35.8, 31.9, 31.8, 28.2, 28.0, 27.8, 24.3, 23.8, 22.8, 22.5, 21.8, 21.0, 19.3, 18.7, 11.8.

[0146] Example 21:

[0147]

[0148] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2b (0.15 mmol, 53.9 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box and turn on the light and the fan to stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate)=10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate)=5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 87%.

[0149] Compound 3ab was tested:

[0150] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.23–8.08 (m, 4H), 7.71–7.61 (m, 2H), 7.56 (t, J = 7.8 Hz, 2H), 7.51–7.43 (m, 2H).

[0151] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.4, 136.4, 134.5, 134.5, 129.9, 129.3, 128.8, 122.8.

[0152] Example 22:

[0153]

[0154] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2c (0.15 mmol, 56.6 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box and turn on the light and the fan to stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate)=10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate)=5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 96%.

[0155] Compound 3ac was tested:

[0156] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.25–8.08 (m, 4H), 7.72–7.61 (m, 1H), 7.54–7.44 (m, 2H), 7.28–7.19 (m, 2H).

[0157] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 167.7, 165.1, 146.3, 134.7, 133.2, 133.1, 132.2, 129.4, 122.8, 116.4, 116.1.

[0158] Example 23:

[0159]

[0160] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2d (0.15 mmol, 58.9 mg) and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 95%.

[0161] Compound 3ad was tested:

[0162] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.16 (d, J = 7.7 Hz, 2H), 8.08 (d, J = 8.7 Hz, 2H), 7.66 (t, J = 7.4 Hz, 1H), 7.56–7.45 (m, 4H).

[0163] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.3, 141.4, 134.7, 131.5, 129.4, 129.2, 122.8.

[0164] Example 24:

[0165]

[0166] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2e (0.15 mmol, 65.7 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 90%.

[0167] Compound 3ae was tested as follows:

[0168] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.16 (d, J = 7.6 Hz, 2H), 8.00 (d, J = 8.3 Hz, 2H), 7.74–7.64 (m, 3H), 7.49 (t, J = 7.9 Hz, 2H).

[0169] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.3, 135.3, 134.8, 132.2, 131.5, 130.1, 129.4, 122.9.

[0170] Example 25:

[0171]

[0172] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2f (0.15 mmol, 64.1 mg), and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 96%.

[0173] Compound 3af was tested as follows:

[0174] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.28 (d, J = 8.1 Hz, 2H), 8.17 (d, J = 8.5 Hz, 2H), 7.83 (d, J = 8.1 Hz, 2H), 7.70–7.64 (m, 1H), 7.50 (t, J = 8.3 Hz, 2H).

[0175] 1313C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.2, 140.1, 135.9 (d, J = 33.1 Hz), 135.0, 130.5, 129.4, 126.0 (d, J = 3.8 Hz), 122.9.

[0176] Example 26:

[0177]

[0178] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2g (0.15 mmol, 62.3 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 78%.

[0179] Compound 3ag was tested:

[0180] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.17 (d, J = 7.7 Hz, 2H), 8.07 (d, J = 8.6 Hz, 2H), 7.67–7.61 (m, 1H), 7.57 (d, J = 8.6 Hz, 2H), 7.48 (t, J = 8.1 Hz, 2H), 1.34 (s, 9H).

[0181] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 158.7, 146.5, 134.4, 133.1, 130.0, 129.3, 125.9, 122.9, 35.4, 31.0.

[0182] Example 27:

[0183]

[0184] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2h (0.15 mmol, 60.6 mg), and ultradry dichloromethane (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, a white solid, is obtained with a yield of 74%.

[0185] Compound 3ah was tested:

[0186] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.98 (s, 1H), 8.59–8.42 (m, 2H), 8.18 (d, J = 8.3 Hz, 2H), 7.80 (t, J = 8.0 Hz, 1H), 7.69 (t, J = 7.4 Hz, 1H), 7.55–7.48 (m, 2H).

[0187] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 148.2, 146.2, 138.8, 135.6, 135.3, 130.3, 129.6, 129.0, 125.4, 123.1.

[0188] Example 28:

[0189]

[0190] In a 10 mL reaction flask, add nitrosobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2i (0.15 mmol, 55.9 mg) and ultra-dry dichloromethane (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 2 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate) = 5:1 is preferred], and a pure product, colorless oil, yield: 85% can be obtained.

[0191] Compound 3ai was tested:

[0192] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.23 (d, J = 7.9 Hz, 1H), 8.17 (d, J = 7.8 Hz, 2H), 7.66 (t, J = 7.4 Hz, 1H), 7.56–7.46 (m, 3H), 7.41 (t, J = 7.7 Hz, 1H), 7.31 (d, J = 7.5 Hz, 1H), 2.68 (s, 3H).

[0193] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.5, 139.0, 135.9, 134.5, 134.2, 132.4, 131.4, 129.4, 126.2, 122.8, 20.8.

[0194] Example 29:

[0195]

[0196] In a 10 mL reaction flask, nitrobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2j (0.15 mmol, 58.9 mg), and ultra-dry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED light box and irradiated with light and stirred with a fan for 2 hours. It was separated and purified by silica gel column chromatography [V(petroleum ether):V(ethyl acetate)=10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate)=5:1 was preferred], and a pure product, a white solid, was obtained with a yield of 72%.

[0197] Compound 3aj was tested:

[0198] 1 H NMR(400MHz,CDCl3,300K):δ(ppm)=8.35–8.27(m,1H),8.20(d,J = 8.0Hz,2H),7.68(t,J = 7.4Hz,1H),7.60–7.48(m,5H).

[0199] 13 C NMR(100MHz,CDCl3,300K):δ(ppm)=146.4,136.3,134.9,134.7,132.9,132.4,131.7,129.4,127.2,123.0.

[0200] Example 30:

[0201]

[0202] In a 10 mL reaction flask, nitrobenzene 1a (0.1 mmol, 10.7 mg), iodoarylimine 2k (0.15 mmol, 60.6 mg), and ultra-dry dichloromethane (1 mL) were added. It was placed in a 24 W blue LED light box and irradiated with light and stirred with a fan for 2 hours. It was separated and purified by silica gel column chromatography [V(petroleum ether):V(ethyl acetate)=10:1 - 3:1, in this example, V(petroleum ether):V(ethyl acetate)=5:1 was preferred], and a pure product, a white solid, was obtained with a yield of 74%.

[0203] Compound 3ak was tested:

[0204] 11H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.54–8.42 (m, 1H), 8.23 (d, J = 8.9 Hz, 2H), 7.88–7.79 (m, 3H), 7.74–7.65 (m, 1H), 7.53 (t, J = 7.8 Hz, 2H).

[0205] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 149.0, 146.2, 135.0, 134.9, 133.6, 132.5, 132.2, 129.5, 124.8, 123.1.

[0206] Example 31:

[0207]

[0208] In a 10 mL reaction flask, add azoxybenzene 3aa (0.1 mmol, 27.6 mg) and ultra-dry tetrahydrofuran (1 mL). Place it in a 24 W blue LED lamp box, turn on the light and the fan, and stir the reaction for 12 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 10:1] to obtain a pure product, yellow oil, yield: 97%.

[0209] Compound 4 was tested:

[0210] 1 1H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.16 (d, J = 8.0 Hz, 2H), 7.54 (t, J = 7.3 Hz, 1H), 7.46 (t, J = 7.7 Hz, 2H), 5.90–5.80 (m, 1H), 4.17–4.01 (m, 2H), 2.51–2.41 (m, 1H), 2.02–1.90 (m, 2H), 1.88–1.78 (m, 1H).

[0211] 13 13C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.9, 131.8, 128.7, 122.0, 92.1, 68.7, 30.5, 24.6.

[0212] Example 32:

[0213]

[0214] In a 10 mL reaction flask, add azoxybenzene 3aa (0.1 mmol, 27.6 mg) and ultradry 2,3-dihydrofuran (1 mL). Place it in a 24 W blue LED light box, turn on the light and the fan, and stir the reaction for 12 hours. Purify by silica gel column chromatography [V(petroleum ether):V(ethyl acetate) = 5:1] to obtain the pure product, which is a yellow oil, yield: 92%.

[0215] Compound 5 was tested as follows:

[0216] 1 H NMR (400 MHz, CDCl3, 300 K): δ (ppm) = 8.02 (d, J = 8.1 Hz, 2H), 7.89 (d, J = 7.9 Hz, 2H), 7.54 (t, J = 7.4 Hz, 1H), 7.45–7.37 (m, 4H), 6.04 (s, 1H), 4.24 (h, J = 8.2 Hz, 2H), 3.82–3.74 (m, 1H), 2.73–2.62 (m, 1H), 2.46 (s, 3H), 2.38–2.28 (m, 1H).

[0217] 13 C NMR (100 MHz, CDCl3, 300 K): δ (ppm) = 146.5, 145.1, 134.9, 132.4, 129.9, 129.0, 128.8, 122.1, 90.9, 68.4, 67.4, 25.4, 21.7.

Claims

1. A method for synthesizing an asymmetric azoxybenzene compound, characterized in that: Dissolve nitroso compound 1 and iminoiodobenzene compound 2 in dichloromethane, and under blue light irradiation, the target product, asymmetric azoxybenzene compound 3, can be obtained; The synthetic route is as follows: Substituent R in nitroso compound 1 1 is alkyl, aryl, heteroaryl; Substituent R in imidobenzene compound 2 2 Selected from benzenesulfonyl groups substituted by alkyl, halogen or nitro at the ortho position, benzenesulfonyl groups substituted by nitro at the meta position, and benzenesulfonyl groups substituted by hydrogen, alkyl or halogen at the para position.

Images