(η 4 -Cyclopentadienyl)osmium heteropentadiene, its preparation methods and applications

Abstract

This invention provides (η) 4 (-Cyclopentadienyl)osmium-pentadienylene, its preparation method and application: Starting from osmium-pentadienylbenzene 1, it reacts with lithium triisopropylsilylacetylene to generate osmium-pentadienylbenzene 2, which is then reacted with lithium phenylacetylene to prepare the catalyst (η). 4 (-cyclopentadienyl)osmium-heptapentane 3; the preparation of this catalyst requires only two steps. Under light and oxygen atmosphere, under irradiation with a 48 W blue LED lamp, 1 mol% (η 4 (-Cyclopentadienyl)osmium pyropentadiene 3 can convert benzylamine into the target imine with a 76% NMR yield after 7 hours at room temperature.

Description

Technical Field

[0001] This invention relates to the fields of organic chemistry, coordination chemistry, and organometallic chemistry, and provides a catalyst, preparation method, and application for the photocatalytic oxidative coupling of benzylamine to imine. Specifically, it relates to a (η) catalyst capable of photocatalytic oxidative coupling of benzylamine to imine. 4 1-Cyclopentadienyl)osmium heteropentadiene, its preparation method and application. Background Technology

[0002] Imines are key intermediates with wide applications in organic synthesis, and are widely used in transformation reactions such as addition, reduction, cyclization and aziridine propanation. They play an important role in the synthesis of nitrogen-containing compounds such as bioactive molecules, natural products and functional materials (Chem. Eur. J. 2024, 30, e2024012345).

[0003] Traditional imines are mainly prepared by condensation reactions of amines with carbonyl compounds (especially aldehydes, which are less stable). However, this method has certain limitations: to promote the forward reaction and improve the yield, dehydrating agents and Lewis acid catalysts are usually added. After the reaction, a large amount of solid waste is generated, which not only increases the difficulty of product separation and purification but also does not conform to the principles of atom economy and environmental friendliness in green chemistry (Org. Lett. 2015, 17, 2442-2445.). Therefore, developing a new green synthesis strategy for imines that is mild, environmentally friendly, and has high atom utilization has become a research hotspot and urgent need in the field of organic synthesis.

[0004] Photocatalysis is a green synthetic technology that utilizes light to excite photocatalysts to generate a transient excited state with reducing activity. It has been proven to efficiently and selectively promote various types of reactions (Chem. Eur. J. 2024, 30, e2024012345). The photocatalytic oxidative coupling of two amine molecules in an oxygen atmosphere has become one of the green synthetic routes for preparing imines. This strategy requires only a photocatalyst and oxygen, without the addition of other auxiliary reagents, and the only byproduct is water, effectively reducing waste generation and significantly improving the greenness and economy of the reaction, perfectly aligning with the development concept of green chemistry (ACS Catal. 2015, 5, 5851-5876). To achieve this type of photocatalytic reaction, the core lies in the structural design and performance regulation of the catalyst. Developing photocatalysts with high catalytic activity, excellent selectivity, and mild reaction conditions has always been a relentless pursuit of researchers. Summary of the Invention

[0005] This invention provides (η) 41-Cyclopentadienyl)osmium-pentadienylene, its preparation method and application: Starting from osmium-pentadienylbenzene 1, it reacts with lithium triisopropylsilylacetyne to generate osmium-pentadienylbenzene 2, which is then reacted with lithium phenylacetyne to obtain the final product (η). 4 -cyclopentadienyl)osmium-heptapentene 3; the preparation of this catalyst only requires two steps.

[0006] Under light and in an oxygen-rich environment, (η) 4 (-cyclopentadienyl)osmium-heptapentaene 3 can efficiently catalyze the oxidative coupling reaction of benzylamine to prepare imine: under irradiation with a 48 W blue LED lamp, 1 mol% (η 4 (-cyclopentadienyl)osmium pentadiene 3 can convert benzylamine into the target imine with a 76% NMR yield after 7 hours at room temperature.

[0007] Firstly, a catalyst is provided, which is (η 4 -cyclopentadienyl)osmium heteropentadiene, with the structural formula shown in Formula 3 below: .

[0008] In a second aspect, a method for synthesizing a catalyst is provided, the method comprising reacting osmium pentadienylbenzyne 2 and lithium phenylacetylene in a first solvent by stirring to obtain the catalyst shown in Formula 3; .

[0009] In some embodiments, the reaction is carried out at 0~45°C for 1~5 hours, preferably at any one of the following ranges: 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 10~40°C, 20~30°C, and any two of the above values. More preferably, the reaction time is 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and any two of the above values.

[0010] In some embodiments, the reaction is carried out under an inert atmosphere.

[0011] In some embodiments, the inert atmosphere is selected from at least one of nitrogen and argon.

[0012] In some embodiments, the molar ratio of osmium pentadienylbenzyne 2 and lithium phenylacetylene is 1:(15~30), preferably 1:15, 1:18, 1:19, 1:20, 1:21, 1:22, 1:25, 1:30, and any two of the above values ​​forming any one of the ranges.

[0013] In some embodiments, the first solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, xylene, etc.

[0014] Thirdly, a method for synthesizing osmium penta-dapenbenzyne 2 is provided, the method comprising reacting osmium penta-dapenbenzyne 1 with lithium triisopropylsilylacetyne in a second solvent by stirring to obtain osmium penta-dapenbenzyne 2; .

[0015] In some embodiments, the reaction is carried out at 0~45°C for 5~15 minutes, preferably at any one of the following ranges: 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 10~40°C, 20~30°C, and any two of the above values. More preferably, the reaction time is 5 minutes, 6 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, and any two of the above values.

[0016] In some embodiments, the reaction is carried out under an inert atmosphere.

[0017] In some embodiments, the inert atmosphere is selected from at least one of nitrogen and argon.

[0018] In some embodiments, the molar ratio of osmium pentadienylbenzene 1 to triisopropylsilyl acetylene lithium is 1:(1~10), preferably 1:1, 1:2, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.6, 1:6, 1:7, 1:8, 1:9, 1:10, and any two of the above values ​​forming any one of the ranges.

[0019] In some embodiments, the second solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, xylene, etc.

[0020] Fourthly, the present invention provides the application of the catalyst described herein in the catalytic oxidative coupling of benzylamine to prepare an imine, comprising: the compound shown in formula (I) under light irradiation conditions via (η) 4 The 3-cyclopentadienyl)osmium-pentadiene catalyzes the reaction to yield the imine shown in formula (II).

[0021] Each R is independently H, F, Cl, Br, I, -OH, -NH2, -NO2, -CN, C 1-6 Alkyl, C 3-8 Cycloalkyl groups, heterocyclic groups consisting of 3-8 atoms, C6-10 Aryl or heteroaryl groups composed of 5-12 atoms; Each n is independently 0, 1, 2, 3, 4 or 5.

[0022] In some embodiments, the reaction is carried out at 0~45°C for 3~24 hours, preferably at any one of the following ranges: 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 10~40°C, 20~30°C, and any two of the above values. More preferably, the reaction time is 5~10 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, and any two of the above values.

[0023] In some embodiments, the reaction needs to be carried out under conditions of oxygen.

[0024] In some embodiments, the illumination uses a blue LED light source.

[0025] In some embodiments, the power of the illumination is 24~60W, preferably any one of the ranges of 24W, 30W, 35W, 40W, 45W, 48W, 50W, 55W, 60W, or any two of the above values.

[0026] In some embodiments, the reaction needs to be carried out in the presence of a third solvent.

[0027] In some embodiments, the third solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, xylene, etc.

[0028] In some embodiments, the compound represented by formula (I) and (η) 4 The molar ratio of 3-cyclopentadienyl)osmium pentadiene 3 is (50~200):1, preferably 50:1, 100:1, 150:1, 200:1, or any two of the above values ​​forming a range.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention can synthesize (η) in two steps. 4 The reaction of 3-cyclopentadienyl)osmium pentadiene is mild, carried out at room temperature, simple to operate, and produces high-yield and highly selective products.

[0030] 2. The method of this invention involves reacting osmium pentyne-benzobenzyl 1 with lithium triisopropylsilylacetyne (triisopropylsilyl = TIPS) in THF solvent at room temperature. After 5-10 minutes, osmium pentyne-benzobenzyl 2 with an acetylene group at position 1 can be obtained with a separation yield of 70%. This complex is then further reacted with lithium phenylacetyne in THF at room temperature, and after 2 hours, complex 3 can be obtained with a separation yield of 40%.

[0031] 3. Catalyst 3 has high catalytic efficiency and requires a small amount of catalyst. Only 1 mol% of catalyst is needed in the catalytic oxidative coupling of benzylamine to prepare imine.

[0032] 4. The catalyst of this invention operates under mild catalytic conditions, efficiently converting benzylamine into the target product imine at room temperature. The catalytic reaction is relatively specific, with few side reactions and high yield. Attached Figure Description

[0033] Figure 1 The image shows the X-ray single-crystal diffraction structure of complex 3.

[0034] Figure 2 For coordination compound 2 1 1H NMR (600 MHz, CD2Cl2) spectrum.

[0035] Figure 3 For coordination compound 2 31 P{ 1 H NMR (243 MHz, CD2Cl2) spectrum.

[0036] Figure 4 For coordination compound 2 13 C{ 1 H NMR (151 MHz, CD2Cl2) spectrum.

[0037] Figure 5 For coordination compound 3 1 1H NMR (600 MHz, CDCl3) spectrum.

[0038] Figure 6 For coordination compound 3 31 P{ 1 ¹H NMR (243 MHz, CDCl₃) spectrum.

[0039] Figure 7 For coordination compound 3 13 C{ 1 H NMR (151 MHz, CDCl3) spectrum.

[0040] All the above spectra were detected using conventional detection methods and conditions in this field.

[0041] Terminology Explanation Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0042] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0043] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] In the following content, all numbers disclosed herein, whether or not they use words such as "approximately" or "about," are approximate values. The value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number with a value of N is disclosed, any numbers with values ​​of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% will be explicitly disclosed, where "+ / -" indicates addition or subtraction. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0047] All reagents used in this invention can be purchased commercially or prepared by the methods described in this invention.

[0048] Ts: p-Toluenesulfonyl; TIPS: Triisopropylsilyl.

[0049] Example 1: Preparation of Complex 2:

[0050] Under a nitrogen atmosphere, complex 1 (2 g, 1.2 mmol) (its preparation method is disclosed in Example 1 of patent CN119899216A) was first added to a 100 mL three-necked flask. Then, 20 mL of THF was added to dissolve the complex. Subsequently, 5 mL of a THF solution of triisopropylsilylacetylene (678.28 mg, 3.6 mmol) was added to the system, and the mixture was stirred at room temperature for 10 minutes to obtain a red solution. The reaction was quenched with saturated NH4Cl aqueous solution (10 mL). The resulting mixture was extracted with dichloromethane (3 × 10 mL), and the extract was concentrated to dryness. The residue was purified by column chromatography (SiO2, 200-300 mesh, eluent: dichloromethane) to obtain a red solid, complex 2 (1.42 g, 70%).

[0051] The specific NMR characterization data of compound 2 are as follows: 1 ¹H NMR (600 MHz, CD₂Cl₂, ppm) δ 8.00 (d, J (HH) = 4.8 Hz, 1H, C5 H ), 7.40(dd, J (HH) = 4.8, 2.4 Hz, 1H, C6 H ), 7.36 (d, J (HH) = 3.4 Hz, 1H, C3 H ), 6.51(dd, J (HH) = 8.5, 6.6 Hz, 1H, C9 H ), 5.81 (d,J (HH) = 6.6 Hz, 1H, C10 H ), 4.91(dt, J (HH) = 8.5, 2.4 Hz, 1H, C8 H ), 0.78 (d, J (HH) = 7.5 Hz, 18H, C H 3 of TIPS), 0.53 (p, J (HH) = 7.5 Hz, 3H, C H of TIPS), 6.82-7.55 (65H, other aromatic protons). 31 P{ 1 ¹H NMR (243 MHz, CD₂Cl₂, ppm) δ 8.18 (t, J (PP) = 7.2 Hz, C P Ph3), -7.55 (d, J (PP) = 7.2 Hz, Os P Ph3). 13 C{ 1 ¹H NMR (151 MHz, CD₂Cl₂, ppm) δ : 328.55 (t, J (PC) = 14.7 Hz, C 11),223.22 - 223.12 (m, C 7), 202.54 (dt, J (PC) = 26.9, 4.5 Hz C 4), 189.62 (td, J (PC) = 13.8, 8.6 Hz C 1), 158.43 (s, C 5), 158.36 (s, C 6), 150.18 (t, J (PC) = 3.5 Hz, C 9), 138.29 (t, J (PC) = 5.9 Hz, C 12), 136.01 ( C 3), 124.41 (s, C 13), 124.16 (s,C 10), 121.05 (s, C 2), 114.19 (s, C 8), 18.69 (s, C H3of TIPS), 11.25 (s, C H of TIPS) and 164.64 - 118.61 (other aromatic carbon atoms). (by 13 C-DEPT 135, 1 H- 13 C HSQC and 1 H- 13 CHMBC testing) The high-resolution mass spectrometry data of compound 2 are as follows: HRMS (ESI): ( m / z ) calcd for2[C 76 H 72 OsP3Si] + 1297.4225, found 1297.4203. Example 2 Preparation of Complex 3:

[0052] Under a nitrogen atmosphere, complex 2 (500 mg, 0.31 mmol) was first added to a 20 mL three-necked flask. Then, 5 mL of THF was added to dissolve the complex. Subsequently, 5 mL of a THF solution of lithium phenylacetylene (668.79 mg, 6.19 mmol) was added to the system, and the mixture was stirred at room temperature for 2 hours. The reaction was quenched with anhydrous methanol (2.5 mL). After the solvent was evaporated, the mixture was dissolved in dichloromethane and filtered. The filtrate was concentrated to dryness. The residue was purified by column chromatography (SiO2, 200-300 mesh, eluent: dichloromethane) to give brown solid 3 (192 mg, 40%).

[0053] The specific NMR characterization data of compound 3 are as follows: 1 ¹H NMR (600 MHz, CDCl₃, ppm) δ 8.47 (s, 1H, C5) H ), 7.80 (s, 1H, C3 H ), 7.46 (s, 1H, C6) H ), 6.35 (s, 1H, C10 H ), 6.20 (s, 1H, C14 H ), 3.49 (d, J(HH) = 17.6 Hz, 1H, C8 H ), 3.18 (s, 1H, C9 H ), 2.62 (d, J (HH) = 17.6 Hz, 1H, C8 H ), 0.84 - 0.71 (m, 21H, C H and C H 3 of TIPS), 7.65 – 5.97 (60H, other aromatic protons). 31 P{ 1 H} NMR (243 MHz, CDCl3, ppm) δ : 8.25 (s, C P Ph3) and 3.14 (s, Os P Ph3). 13 C{ 1 H} NMR (151 MHz, CDCl3, ppm) δ : 252.79 (s, C 7), 208.83 - 206.57 (m, C 4), 178.67 (s, C 1), 160.26 (s, C 5), 157.34 (s, C 6), 152.20 (d, J (PC) = 22.9 Hz, C 3), 133.16 (s, C of alkyne), 132.80 (s, C of alkyne), 123.22 (s, C of alkyne),122.21 (d, J (PC) = 9.6 Hz, C 2), 106.77 (s, C 14), 118.69 (s, C of alkyne), 91.54(d, J (PC) = 12.8 Hz, C 15), 83.96 (s, C 9), 76.53 (s, C 11), 65.18 (s, C8), 61.23 (s, C 10), 18.54 (d, J (PC) = 42.4 Hz C H3of TIPS), 11.56 (s, C H of TIPS) and 164.88 -121.61 (other aromatic carbon atoms). (by 13 C-DEPT 135, 1 H- 13 C HSQC and 1 H- 13 (CHMBC detection). The high-resolution mass spectrometry data of compound 3 are as follows: HRMS (ESI): ( m / z ) calcd for3[C 74 H 69 OsP2Si] + 1239.4253, found 1239.4241. The X-ray single-crystal diffraction structure of compound 3 is as follows: Figure 1 As shown, some of the bond lengths and bond angles are shown in Table 1.

[0054] Table 1. Partial bond lengths and bond angles of single crystals of complex 3

[0055] As shown in Table 1, the bond lengths of the seven Os-C bonds connected to the center of metallic osmium—Os1-C1, Os1-C4, Os1-C7, Os1-C10, Os1-C11, Os1-C14, and Os1-C15—are 2.108(4), 2.045(4), 2.043(4), 2.254(4), 2.264(4), 2.252(4), and 2.340(4) Å, respectively, with Os1-C7 being the shortest. The C-C bond lengths on the double pentagonal ring composed of eight atoms (C1 to C7 and Os1) range from 1.378(7) to 1.415(6) Å, which are shorter than the localized single bond lengths but longer than the localized double bond lengths, indicating that this double pentagonal ring structure has a certain degree of delocalization.

[0056] Example 3: Photocatalytic oxidative coupling of complex 3 with benzylamine to prepare imine 4:

[0057] In a 10 mL Schlenk tube, complex 3 (15.58 mg, 0.01 mmol), 5 mL of CH3CN, and benzylamine Ia (107.2 mg, 1 mmol) were added sequentially. The Schlenk tube was then placed in an atmosphere of air, oxygen, or nitrogen, with a 48 W blue LED lamp positioned approximately 5 cm away. The reaction temperature was maintained at room temperature using a water bath. 1 The reaction was monitored by ¹H NMR. After the reaction was complete, the solvent was dried, and then 0.5 mmol of 1,3,5-trimethoxybenzene was added to the reaction tube as an internal standard, which was then dissolved in CDCl₃ and passed through the solvent. 1 The conversion rate of the reaction and the yield of product IIa were calculated by ¹H NMR. The results were obtained by integrating the characteristic peaks of the product and reactants, as shown in Table 2.

[0058] Table 2 Catalyst (η) 4 Results of the catalytic reaction of (-cyclopentadienyl)osmium-heptapentane

[0059] The results in Table 2 show that the catalyst and light irradiation are crucial for the photocatalytic oxidative coupling of benzylamine to imine. Under blue light irradiation, (η 4 (-cyclopentadienyl)osmium-heptapentene 3 catalyzes the oxidative coupling reaction of benzylamine to prepare imine compound IIa in CH3CN solvent at room temperature. In entry 1, under 48 W blue LED illumination, with a reaction time limited to 7 hours, a reaction temperature limited to room temperature, and a catalyst equivalent of 1 mol%, the conversion of the starting material benzylamine reached 100% in an O2 atmosphere, and the NMR yield of the target product IIa reached 76%. If the O2 atmosphere was replaced with air, the conversion and NMR yield of entry 2 decreased to 65% and 17%, respectively, indicating that oxygen has a significant effect on improving reaction efficiency. If the N2 atmosphere was used, the yield of entry 3 was very low, only about 2.6%. If the reaction was carried out in darkness instead of under light, no target product was observed in entry 4, indicating that light is indispensable for the reaction. Without a catalyst, under the same conditions as entry 1, almost no target product was observed in entry 5 (yield 1.1%), indicating that (η) 4 3-Cyclopentadienyl)osmium-heptapentene 3 does indeed play a key role as a catalyst.

[0060] The method of this invention has been described through preferred embodiments. Those skilled in the art will readily be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and context of this invention to implement and apply the technology of this invention. Those skilled in the art can refer to the content herein to appropriately improve process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this invention.

Claims

1. A catalyst, characterized in that, It is (η) 4 -cyclopentadienyl)osmium heteropentadiene, with the structural formula shown in Formula 3 below: 。 2. A method for synthesizing the catalyst according to claim 1, characterized in that, The method includes preparing the catalyst shown in Formula 3 by stirring and reacting osmium-pentadienylene-2 ​​and lithium phenylacetylene in a first solvent; 。 3. The synthesis method according to claim 2, characterized in that, The reaction was carried out at 0-45°C for 1-5 hours; Preferably, the reaction is carried out under an inert atmosphere; Preferably, the inert atmosphere is selected from at least one of nitrogen and argon; Preferably, the molar ratio of osmium pentadienylbenzyne 2 to lithium phenylacetylene is 1:(15~30). Preferably, the first solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, and xylene.

4. A method for synthesizing osmium-pentadienylbenzyne 2 as described in claim 2, characterized in that, The method includes preparing osmium-pentadienylbenzene 1 by stirring and reacting it with triisopropylsilylacetylenite in a second solvent to obtain osmium-pentadienylbenzene 2; 。 5. The synthesis method according to claim 4, characterized in that, The reaction was carried out at 0-45°C for 5-15 minutes; Preferably, the reaction is carried out under an inert atmosphere; Preferably, the inert atmosphere is selected from at least one of nitrogen and argon.

6. The synthesis method according to claim 4, characterized in that, The molar ratio of osmium pentadienylbenzene 1 to triisopropylsilylacetylenite lithium is 1:(1~10). Preferably, the second solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, and xylene.

7. The application of the catalyst according to claim 1 in the catalytic oxidative coupling of benzylamine to prepare imine, characterized in that, include: The compound shown in formula (I) under light irradiation undergoes (η) 4 The 3-cyclopentadienyl)osmium-pentadiene catalyzes the reaction to yield the imine shown in formula (II). ， Each R is independently H, F, Cl, Br, I, -OH, -NH2, -NO2, -CN, C 1-6 Alkyl, C 3-8 Cycloalkyl groups, heterocyclic groups consisting of 3-8 atoms, C 6-10 Aryl or heteroaryl groups composed of 5-12 atoms; Each n is independently 0, 1, 2, 3, 4 or 5.

8. The application according to claim 7, characterized in that, The reaction is carried out at 0-45°C for 3-24 hours; the reaction needs to be carried out under oxygen-containing conditions.

9. The application according to claim 7, characterized in that, The illumination uses a blue LED light source; Preferably, the power of the illumination is 24~60W; Preferably, the reaction needs to be carried out in the presence of a third solvent; Preferably, the third solvent is selected from at least one of acetone, acetonitrile, diethyl ether, ethyl acetate, n-hexane, n-heptane, dioxane, dichloromethane, THF, toluene, xylene, etc.

10. The application according to claim 7, characterized in that, The compound shown in formula (I) and (η) 4 The molar ratio of 3-cyclopentadienyl)osmium pentadiene 3 is (50~200):1.

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