Preparation method of hydrogen-containing silane mediated benzoxazole derivative

Abstract

The invention relates to the technical field of organic synthesis, in particular to a preparation method of hydrogen-containing silane mediated benzoxazole derivatives, which comprises the following steps: (2-nitrophenyl) benzoate and analogues thereof as nitro substrates are dissolved in acid liquor with a palladium catalyst, hydrogen-containing silane is slowly injected, reaction is carried out under normal pressure, after the reaction is finished, a reaction product is subjected to post-treatment, and the hydrogen-containing silane mediated benzoxazole derivatives are obtained. Separating and purifying to obtain a target product benzoxazole derivative. The novel synthesis method of benzoxazole and derivatives thereof is adopted, high-pressure hydrogen and inert gas protection required by a traditional hydrogenation method is abandoned, nitro reduction and cyclization are completed in one step, and a safe, economical and environment-compatible synthesis scheme is provided for large-scale production of benzo-azacyclo drug intermediates.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes. Background Technology

[0002] Benzo[a]azine heterocyclic derivatives (such as benzoxazole) are crucial core frameworks in drug synthesis, widely used in the preparation of intermediates for antibacterial, anti-inflammatory, and antitumor drugs. The key to their synthesis lies in the efficient reduction of the nitro group and the synergistic construction of the cyclization reaction; however, current mainstream methods suffer from significant technical bottlenecks. Current synthesis of benzo[a]azine compounds often employs a stepwise reduction-cyclization strategy, requiring high-pressure hydrogen, expensive transition metal catalysts, or highly corrosive reagents (such as H2 / Pd-C, NaBH4 / FeCl3), resulting in high operational risks, cumbersome reaction steps, and poor functional group compatibility. Furthermore, traditional methods are sensitive to reaction conditions, making it difficult to achieve synergistic cyclization of the nitro group with neighboring functional groups.

[0003] In recent years, although studies have attempted to improve the synthetic processes of benzo[a]azine heterocyclic compounds, such as using transition metal-catalyzed CH-activated cyclization (e.g., copper / oxime acid systems) or photocatalytic nitro reduction strategies (e.g., Ru(bpy)3²), + While these methods (such as those using visible light) still have significant limitations, the CH activation method, for example, is highly dependent on the pre-installation of directing groups, which limits the flexibility of substrate design and often requires the use of stoichiometric oxidants (such as potassium persulfate), generating a large amount of inorganic salt byproducts. Although photocatalytic systems offer milder conditions, they face challenges such as high cost of light source equipment and difficulties in reaction scale-up. Therefore, developing a universal method for nitro reduction cyclization that combines atom economy, ease of operation, and environmental friendliness remains a critical technological bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes. This invention achieves controllable reductive cyclization under gradient temperature control in an acetic acid medium through the synergistic effect of hydrogen-containing silanes and palladium-on-carbon catalysts, solving problems such as hazardous operation, cumbersome steps, and poor functional group compatibility in existing technologies, and providing an innovative pathway for the green synthesis of pharmaceutical intermediates.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes is provided, comprising the following steps: (2-Nitrophenyl)benzoate and its analogues were used as nitro bases, dissolved in acid with a palladium catalyst, and the reaction was carried out under normal pressure by slow injection of hydrogen-containing silane. After the reaction was completed, the target product, a benzoxazole derivative, was obtained by separation and purification.

[0006] Furthermore, nitrocellulose compounds include, but are not limited to, (2-nitrophenyl)benzoate, (2-nitrophenyl)-4-methylbenzoate, (2-nitrophenyl)-3-methylbenzoate, (2-nitrophenyl)-4-chlorobenzoate, (5-fluoro-2-nitrophenyl)benzoate, (2-nitrophenyl)-2-methylbenzoate, (4-methyl-2-nitrophenyl)benzoate, (4-methyl-2-nitrophenyl)-2-methylbenzoate, (4-fluoro-2-nitrophenyl)benzoate, (2-nitrophenyl)benzoate, etc. (2-Nitrophenyl)acetate, (3,4-dimethyl-2-nitrophenyl)benzoate, (2-nitrophenyl)acetate, (2-nitrophenyl)propionate, (4-bromo-2-nitrophenyl)benzoate, (4-methoxy-2-nitrophenyl)benzoate, (4-amino-2-nitrophenyl)benzoate, (4-cyano-2-nitrophenyl)benzoate, [4-(methoxycarbonyl)-2-nitrophenyl]benzoate, (2-nitrophenyl)-3-methylbutyrate, tert-butyl(2-nitrophenyl)carbonate.

[0007] Furthermore, the hydrogen-containing silanes include, but are not limited to, trimethylsilane, dimethyl(ethyl)silane, n-butylsilane, triisopropylsilane, tributylsilane, tri(fluoroisopropyl)silane, tri(chloromethyl)silane, tri(trifluoromethyl)silane, tri(trimethylsiloxy)silane, di(trimethylsiloxy)ethylsilane, diphenylsilane, methylphenylsilane, and cyclohexylsilane.

[0008] Furthermore, the catalyst includes, but is not limited to, Pd / C, PdCl2, Pd(OAc)2 metal catalysts or non-metal catalysts, wherein the non-metal catalysts include boron catalysts, carbon-based catalysts or transition metal oxide catalysts.

[0009] Furthermore, benzoxazole derivatives include, but are not limited to, 2-phenylbenzoxazole, 2-(p-methylphenyl)benzoxazole, 2-(3-methylphenyl)benzoxazole, 2-(4-chlorophenyl)benzoxazole, 6-fluoro-2-phenylbenzoxazole, 2-(2-methylphenyl)benzoxazole, 5-methyl-2-phenylbenzoxazole, 5-methyl-2-(2-methylphenyl)benzoxazole, and 5-fluoro-2-phenylbenzoxazole. 2-(chloromethyl)benzoxazole, 5,6-dimethyl-2-phenylbenzoxazole, 2-methylbenzoxazole, 2-ethylbenzoxazole, 5-bromo-2-phenylbenzoxazole, 5-methoxy-2-phenylbenzoxazole, 5-amino-2-phenylbenzoxazole, 5-cyano-2-phenylbenzoxazole, 5-(methoxycarbonyl)-2-phenylbenzoxazole, 2-(2-methylpropyl)benzoxazole, 2-hydroxybenzoxazole.

[0010] Furthermore, the acid liquid includes, but is not limited to, acetic acid, propionic acid, trifluoroacetic acid, benzoic acid, o-nitrobenzoic acid, p-toluenesulfonic acid, methanesulfonic acid, acidic ionic liquids, sulfuric acid, hydrochloric acid, phosphoric acid, citric acid, and sulfonic acid ionic liquids.

[0011] Furthermore, the reaction temperature is 60-140℃, preferably 80-120℃; the reaction time is 1-24h, preferably 4-12h.

[0012] Furthermore, the reaction temperature is gradually increased from 60℃ to 140℃, preferably 80-120℃; the reaction time is 1-24h, preferably 4-12h.

[0013] Furthermore, the molar ratio of the nitro base to the hydrogen-containing silane is 1:2 to 1:6, preferably 1:3 to 1:5.

[0014] Furthermore, the amount of palladium catalyst used is 1wt%-10wt% of the nitro base, preferably 3wt%-7wt%.

[0015] Furthermore, the hydrogen-containing silane is added by slow injection, with an injection time of more than 10 minutes, preferably 30 minutes to 2 hours, and the injection rate is controlled at 0.1-5 mL / min.

[0016] Furthermore, the reaction does not require inert gas protection and is carried out at atmospheric pressure.

[0017] Furthermore, the palladium catalyst is Pd / C and can be recycled and reused, retaining more than 80% of its original catalytic activity after recycling.

[0018] Furthermore, the nitro reduction and cyclization reaction are completed in one step without the need to separate intermediates, with an atom economy of over 90% and a product purity of ≥95%.

[0019] The beneficial effects of this invention are as follows: 1. Mild conditions and high safety. The reaction occurs at atmospheric pressure, eliminating the need for high-pressure hydrogen or inert gas protection, making operation simple. Gradient temperature control manages the reaction progress and reduces byproduct formation.

[0020] 2. Green and environmentally friendly with high atom economy. Using acetic acid as a solvent and hydrogen-containing silanes as reducing agents, nitro reduction and cyclization are completed simultaneously without the need to separate intermediate products.

[0021] 3. High substrate versatility. Compatible with various functional groups such as halogens (Cl, Br, F), methoxy, and amino groups, it can synthesize complex derivatives such as 2-phenylbenzoxazole, 5-methyl-2-phenylbenzoxazole, 5-bromo-2-phenylbenzoxazole, 2-(4-aminophenyl)benzoxazole, 2-(3,5-dichlorophenyl)benzoxazole, and 5-fluoro-2-phenylbenzoxazole.

[0022] 4. Economic viability and scalability potential. Palladium-on-carbon catalyst requires low dosage, can be reused, and has a simple reaction system.

[0023] 5. High selectivity: By controlling the silane injection rate through slow, batch-by-batch injection, excessive reduction of nitro groups and destruction of adjacent functional groups (such as halogens and cyano groups) are avoided, resulting in a product purity of ≥95%. Attached Figure Description

[0024] Figure 1a The 1H NMR spectrum of 2-phenylbenzoxazole prepared in Example 1 of this invention; Figure 1b The carbon NMR spectrum of 2-phenylbenzoxazole prepared in Example 1 of this invention; Figure 2a The 1H NMR spectrum of 2-(p-methylphenyl)benzoxazole prepared in Example 2 of this invention; Figure 2b The carbon NMR spectrum of 2-(p-methylphenyl)benzoxazole prepared in Example 2 of this invention; Figure 3a The 1H NMR spectrum of 2-(3-methylphenyl)benzoxazole prepared in Example 3 of this invention; Figure 3b The carbon NMR spectrum of 2-(3-methylphenyl)benzoxazole prepared in Example 3 of this invention; Figure 4a The 1H NMR spectrum of 2-(4-chlorophenyl)benzoxazole prepared in Example 4 of this invention; Figure 4b The carbon NMR spectrum of 2-(4-chlorophenyl)benzoxazole prepared in Example 4 of this invention; Figure 5a The 1H NMR spectrum of 6-fluoro-2-phenylbenzoxazole prepared in Example 5 of this invention; Figure 5b The carbon NMR spectrum of 6-fluoro-2-phenylbenzoxazole prepared in Example 5 of this invention; Detailed Implementation The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0025] Example 1: Synthesis of 2-phenylbenzoxazole 0.486 g (2 mmol) of (2-nitrophenyl)benzoate was weighed and added to a 250 mL three-necked round-bottom flask. Then, 24 mg (5 wt%) of Pd / C, 10 mL of acetic acid, and 0.456 g (4 mmol) of trifluoroacetic acid were added. The flask was sealed with a reflux reflux device and placed in an 80 °C oil bath with stirring. 0.928 g (8 mmol) of triethylsilane was weighed and slowly injected into the flask in batches. The temperature was gradually increased from 80 °C to 120 °C, and the reaction was carried out for 6 h. After the reaction was complete, the product was purified by chromatography to obtain 0.343 g, with a calculated yield of 88%.

[0026] The products prepared in this embodiment were subjected to proton and carbon spectroscopy analyses, and the product structures are as follows: according to Figure 1a Hydrogen spectroscopy analysis can determine: 1 H NMR (400 MHz, DMSO) δ 8.22 (dt, J = 6.7, 1.9 Hz, 2H), 7.85 – 7.79 (m, 2H), 7.71 – 7.58 (m, 4H), 7.47 – 7.41 (m, 2H). Therefore, the hydrogen atom assignment in the product obtained in this example is the same as that in 2-phenylbenzoxazole.

[0027] according to Figure 1b Carbon spectroscopy analysis can determine: 13 C NMR (101 MHz, DMSO) δ 162.71, 150.69, 147.08, 143.33, 141.96, 132.41, 129.77, 127.72, 125.98, 125.33, 120.30, 119.32, 111.39. Therefore, the carbon atom assignments in the product obtained in this experiment are the same as those in 2-phenylbenzoxazole.

[0028] Example 2: Synthesis of 2-(p-methylphenyl)benzoxazole 0.514 g (2 mmol) of (2-nitrophenyl)-4-methylbenzoate was weighed and added to a 250 mL three-necked round-bottom flask. Then, 26 mg (5 wt%) of Pd / C, 10 mL of acetic acid, and 0.456 g (4 mmol) of trifluoroacetic acid were added. The flask was sealed with a reflux reflux device and placed in an 80 °C oil bath with stirring. 0.928 g (8 mmol) of triethylsilane was weighed and slowly injected into the flask in batches. The temperature was gradually increased from 80 °C to 120 °C, and the reaction was carried out for 6 h. After the reaction was complete, the product was purified by chromatography to obtain 0.355 g, with a calculated yield of 85%.

[0029] The products prepared in this embodiment were subjected to proton and carbon spectroscopy analyses, and the product structures are as follows: according to Figure 2a Hydrogen spectroscopy analysis can determine: 1 ¹H NMR (400 MHz, DMSO) δ 8.14 – 8.06 (m, 2H), 7.83 – 7.75 (m, 2H), 7.48 – 7.38 (m, 4H), 2.42 (s, 3H). Therefore, the hydrogen atom assignment in the product obtained in this example is the same as that in 2-(p-methylphenyl)benzoxazole.

[0030] according to Figure 2b Carbon spectroscopy analysis can determine: 13 C NMR (101 MHz, DMSO) δ 162.92, 150.62, 142.63, 142.04, 130.37, 127.73, 125.78, 125.27, 124.19, 120.14, 111.30. Therefore, the carbon atom assignments in the product obtained in this example are the same as those in 2-(p-methylphenyl)benzoxazole.

[0031] Example 3: Synthesis of 2-(3-methylphenyl)benzoxazole 0.514 g (2 mmol) of (2-nitrophenyl)-3-methylbenzoate was weighed and added to a 250 mL three-necked round-bottom flask. Then, 26 mg (5 wt%) of Pd / C, 10 mL of acetic acid, and 0.456 g (4 mmol) of trifluoroacetic acid were added. The flask was sealed with a reflux reflux device and placed in an 80 °C oil bath with stirring. 0.928 g (8 mmol) of triethylsilane was weighed and slowly injected into the flask in batches. The temperature was gradually increased from 80 °C to 120 °C, and the reaction was carried out for 6 h. After the reaction was complete, the product was purified by chromatography to obtain 0.368 g, with a calculated yield of 88%.

[0032] The products prepared in this embodiment were subjected to proton and carbon spectroscopy analyses, and the product structures are as follows: according to Figure 3a Hydrogen spectroscopy analysis can determine: 1 ¹H NMR (400 MHz, DMSO) δ 8.06 – 7.97 (m, 2H), 7.84 – 7.75 (m, 2H), 7.54 – 7.40 (m, 4H), 2.44 (s, 3H). Therefore, the hydrogen atom assignment in the product obtained in this example is the same as that in 2-(3-methylphenyl)benzoxazole.

[0033] according to Figure 3b Carbon spectroscopy analysis can determine: 13 C NMR (101 MHz, DMSO) δ 162.82, 150.65, 141.98, 139.29, 133.05, 129.64, 128.23, 126.82, 125.90, 125.28, 124.90, 120.23, 111.33. Therefore, the carbon atom assignments in the product obtained in this example are the same as those in 2-(3-methylphenyl)benzoxazole.

[0034] Example 4: Synthesis of 2-(4-chlorophenyl)benzoxazole Weigh 0.555 g (2 mmol) of (2-nitrophenyl)-4-chlorobenzoate and add it to a 250 mL three-necked round-bottom flask. Then add 27 mg (5 wt%) of Pd / C, 10 mL of acetic acid, and 0.456 g (4 mmol) of trifluoroacetic acid. Seal the flask with a reflux reflux device and place it in an 80 °C oil bath with stirring. Weigh 0.928 g (8 mmol) of triethylsilane and slowly inject it into the flask in batches. Gradually increase the temperature from 80 °C to 120 °C and react for 6 h. After the reaction is complete, chromatographic separation and purification of the product yields 0.367 g, with a calculated yield of 80%.

[0035] The products prepared in this embodiment were subjected to proton and carbon spectroscopy analyses, and the product structures are as follows: according to Figure 4a Hydrogen spectroscopy analysis can determine: 1 ¹H NMR (400 MHz, DMSO) δ 8.24 – 8.17 (m, 2H), 7.86 – 7.78 (m, 2H), 7.74 – 7.66 (m, 2H), 7.50 – 7.39 (m, 2H). Therefore, the hydrogen atom assignment in the product obtained in this example is the same as that in 2-(4-chlorophenyl)benzoxazole.

[0036] according to Figure 4b Carbon spectroscopy analysis can determine: 13 C NMR (101 MHz, DMSO) δ 161.82, 150.74, 141.88, 137.21, 129.98, 129.49, 127.74, 126.25, 125.78, 125.50, 120.41, 111.49. Therefore, the carbon atom assignments in the product obtained in this example are the same as those in 2-(4-chlorophenyl)benzoxazole.

[0037] Example 5: Synthesis of 6-fluoro-2-phenylbenzoxazole 0.522 g (2 mmol) of (2-nitrophenyl)-5-fluorobenzoate was weighed and added to a 250 mL three-necked round-bottom flask. Then, 26 mg (5 wt%) of Pd / C, 10 mL of acetic acid, and 0.456 g (4 mmol) of trifluoroacetic acid were added. The flask was sealed with a reflux reflux device and placed in an 80 °C oil bath with stirring. 0.928 g (8 mmol) of triethylsilane was weighed and slowly injected into the flask in batches. The temperature was gradually increased from 80 °C to 120 °C, and the reaction was carried out for 6 h. After the reaction was complete, the product was purified by chromatography to obtain 0.349 g, with a calculated yield of 82%.

[0038] The products prepared in this embodiment were subjected to proton and carbon spectroscopy analyses, and the product structures are as follows: according to Figure 5a Hydrogen spectroscopy analysis can determine: 1 H NMR (400 MHz, DMSO) δ 8.20 (dt, J = 8.2, 1.6 Hz, 2H), 7.82 (ddd, J = 8.9, 4.4, 1.4 Hz, 1H), 7.74 – 7.58 (m, 4H), 7.30(tdd, J = 8.8, 4.0, 2.0 Hz, 1H). Therefore, the hydrogen atom assignment in the product obtained in this embodiment is the same as that in 6-fluoro-2-phenylbenzoxazole.

[0039] according to Figure 5b Carbon spectroscopy analysis can determine: 13 C NMR (101 MHz, DMSO) δ 164.55, 161.23, 158.86, 147.22, 142.78, 132.66, 129.77, 127.79, 126.59, 113.25, 112.21, 106.51. Therefore, the carbon atom assignments in the product obtained in this example are the same as those in 6-fluoro-2-phenylbenzoxazole.

[0040] In summary, this invention employs a novel synthetic method for benzoxazole and its derivatives, eliminating the need for high-pressure hydrogen and inert gas protection required by traditional hydrogenation methods. It achieves nitro reduction and cyclization in one step, providing a safe, economical, and environmentally compatible synthetic scheme for the large-scale production of benzoxazole heterocyclic drug intermediates.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0042] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a benzoxazole derivative mediated by a hydrogen-containing silane, characterized in that, Includes the following steps: (2-Nitrophenyl)benzoate and its analogues were used as nitro bases, dissolved in acid with a palladium catalyst, and then injected with hydrogen-containing silane. The reaction was carried out under normal pressure. After the reaction was completed, the target product, a benzoxazole derivative, was obtained by separation and purification.

2. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The nitro compounds include (2-nitrophenyl)benzoate, (2-nitrophenyl)-4-methylbenzoate, (2-nitrophenyl)-3-methylbenzoate, (2-nitrophenyl)-4-chlorobenzoate, (5-fluoro-2-nitrophenyl)-benzoate, (2-nitrophenyl)-2-methylbenzoate, (4-methyl-2-nitrophenyl)benzoate, (4-methyl-2-nitrophenyl)-2-methylbenzoate, (4-fluoro-2-nitrophenyl)-benzoate, and (2-nitrophenyl)- 2-Chloroacetic acid ester, (3,4-dimethyl-2-nitrophenyl)benzoate, (2-nitrophenyl)acetic acid ester, (2-nitrophenyl)propionate, (4-bromo-2-nitrophenyl)benzoate, (4-methoxy-2-nitrophenyl)benzoate, (4-amino-2-nitrophenyl)benzoate, (4-cyano-2-nitrophenyl)benzoate, [4-(methoxycarbonyl)-2-nitrophenyl]benzoate, (2-nitrophenyl)-3-methylbutyrate, tert-butyl(2-nitrophenyl)carbonate.

3. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The hydrogen-containing silanes include trimethylsilane, dimethyl(ethyl)silane, n-butylsilane, triisopropylsilane, tributylsilane, tri(fluoroisopropyl)silane, tri(chloromethyl)silane, tri(trifluoromethyl)silane, tri(trimethylsiloxy)silane, di(trimethylsiloxy)ethylsilane, diphenylsilane, methylphenylsilane, and cyclohexylsilane.

4. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The catalysts include Pd / C, PdCl2, Pd(OAc)2 metal catalysts and non-metal catalysts, and the non-metal catalysts include boron catalysts, carbon-based catalysts and transition metal oxide catalysts.

5. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The benzoxazole derivatives include 2-phenylbenzoxazole, 2-(4-methylphenyl)benzoxazole, 2-(3-methylphenyl)benzoxazole, 2-(4-chlorophenyl)benzoxazole, 6-fluoro-2-phenylbenzoxazole, 2-(2-methylphenyl)benzoxazole, 5-methyl-2-phenylbenzoxazole, 5-methyl-2-(2-methylphenyl)benzoxazole, 5-fluoro-2-phenylbenzoxazole, 2- (chloromethyl)benzoxazole, 5,6-dimethyl-2-phenylbenzoxazole, 2-methylbenzoxazole, 2-ethylbenzoxazole, 5-bromo-2-phenylbenzoxazole, 5-methoxy-2-phenylbenzoxazole, 5-amino-2-phenylbenzoxazole, 5-cyano-2-phenylbenzoxazole, 5-(methoxycarbonyl)-2-phenylbenzoxazole, 2-(2-methylpropyl)benzoxazole, 2-hydroxybenzoxazole.

6. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The acid solution includes acetic acid, propionic acid, trifluoroacetic acid, benzoic acid, o-nitrobenzoic acid, p-toluenesulfonic acid, methanesulfonic acid, acidic ionic liquid, sulfuric acid, hydrochloric acid, phosphoric acid, citric acid, and sulfonic acid ionic liquid.

7. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The reaction temperature is 60-140℃; the reaction time is 1-24h.

8. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The molar ratio of the nitro base to the hydrogen-containing silane is 1:2 to 1:

6.

9. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The amount of palladium catalyst used is 1wt%-10wt% of the nitro base.

10. The method for preparing benzoxazole derivatives mediated by hydrogen-containing silanes according to claim 1, characterized in that, The hydrogen-containing silane is added by slow injection, with the injection time exceeding 10 minutes and the injection rate controlled at 0.1-5 mL / min.

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