A method for preparing an organic boron compound
Through the metal salt catalytic system without ligands, the problem of scarce reserves and complex treatment of precious metal catalysts is solved in the anti-maflora borogen reaction between olefins and boron compounds, and the green and simple preparation of organic boron compounds is achieved, and it has great application value.
Patent Information
- Application Number
- CN202210979173.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-16
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2042-08-16
AI Technical Summary
In the existing preparation methods for organic boron compounds, precious metal catalysts have few reserves, are expensive, have high toxicity and are complicated to process, which limits their wide application.
Organoboron compounds are prepared by anti-mafranilon hydrotization reaction of olefins and boron compounds under the action of metal salts using metal salts without ligands.
It has achieved green and easy-to-access reaction raw materials, gentle reaction conditions, simple experimental operations, and good substrate compatibility preparation of organic boron compounds, which has great application value and socio-economic benefits.
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Figure CN115197256B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to material technology, and in particular to a method for preparing an organic boron compound. Background Art
[0002] Organoboron compounds are among the most versatile intermediates in organic synthesis, being stable and easy to handle. They are not only widely used in Suzuki-Miyaura cross-coupling reactions with aryl and alkyl halides, but can also be readily converted into a variety of chemical bonds, including carbon-carbon, carbon-hydrogen, and carbon-hetero bonds. Their synthesis and application occupy a crucial position in organic chemistry. Transition-metal-catalyzed hydroboration of olefins, characterized by its simplicity, high efficiency, atom economy, and excellent selectivity, is one of the most effective methods for constructing alkylboronic acid esters. For the past few decades, noble metal catalysts such as rhodium, ruthenium, palladium, and iridium have dominated the hydroboration of olefins. Rhodium, in particular, has been widely used in organic synthesis due to its exceptionally high catalytic efficiency and regioselectivity. However, the scarcity of these noble metals in the Earth's crust, their high cost, high toxicity, and cumbersome post-processing have limited their widespread application. With the pursuit of green chemistry and sustainable development, efforts are underway to identify alternative catalysts to these noble metals. Cheap transition metals, which are abundant in the earth's crust, are considered to be ideal substitutes for precious metals. Therefore, it is of great research significance to develop a simple metal salt catalytic system without external ligands to prepare organoboron compounds using olefins. Summary of the Invention
[0003] The purpose of the present invention is to address the problems existing in the above-mentioned current preparation methods of organic boron compounds and propose a preparation method of organic boron compounds. The method has the advantages of green and readily available reaction raw materials, mild reaction conditions, simple experimental operation, good substrate compatibility, and easy industrialization, and thus has great application value and socio-economic benefits.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing an organic boron compound, using styrene and a boron compound as raw materials, in a system without added ligands, styrene and the boron compound undergo an anti-Markovnikov hydroboration reaction under the action of a metal salt to synthesize the organic boron compound.
[0005] The reaction equation is as follows:
[0006]
[0007] Furthermore, the preparation method of the organic boron compound specifically includes the following steps: adding the catalyst and additives in sequence to a Schlenk reaction tube with a magnet, replacing the reactor with nitrogen three times, adding styrene (derivative), solvent and boron compound in sequence to the Schlenk reaction tube under nitrogen flow, and placing it on a magnetic stirrer for reaction to prepare the organic boron compound.
[0008] Furthermore, R on the styrene (derivative) 1 is selected from fluorine, chlorine, bromine, nitro, ester, methyl, hydroxy, amino, trifluoromethoxy, methoxy or ethoxy; R 1 In the ortho, meta or para position of the aromatic ring.
[0009] Furthermore, the catalyst is selected from one or more of manganese chloride, manganese acetate, manganese carbonate, manganese bromide, copper chloride, copper bromide, copper carbonate and copper acetate.
[0010] Furthermore, the additive is selected from one or more of potassium tert-butoxide, ammonium chloride, sodium chloride, potassium chloride, ammonium fluoride, ammonium bromide, sodium bromide, potassium bromide, sodium carbonate and potassium carbonate.
[0011] Furthermore, the solvent is selected from one or more of toluene, n-hexane, tetrahydrofuran, 1,4-dioxane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dichloromethane, chloroform, acetone and acetonitrile.
[0012] Furthermore, the boron compound is selected from pinacol diborate and / or pinacol borane.
[0013] Furthermore, the molar ratio of the styrene (derivative) to the catalyst is 1:0.01 to 1:0.5, preferably 1:0.1 to 1:0.4.
[0014] Furthermore, the molar ratio of the styrene (derivative) to the additive is 1:0.2 to 1:10, preferably 1:2 to 1:8.
[0015] Furthermore, the molar content of the styrene (derivative) in the solvent is 0.01 mmol / mL to 2 mmol / mL, preferably 0.5 mmol / mL to 1.0 mmol / mL.
[0016] Furthermore, the molar ratio of the styrene (derivative) to the boron compound is 1:0.1 to 1:10, preferably 1:2 to 1:6.
[0017] Furthermore, the reaction temperature is 30-150°C, preferably 30-80°C.
[0018] Furthermore, the reaction time is 1 to 48 hours, preferably 8 to 24 hours.
[0019] Another object of the present invention is to disclose an organic boron compound and a preparation method thereof, which are prepared using the above preparation method.
[0020] The present method for preparing an organoboron compound has the following advantages over existing technologies: It primarily provides a novel, simple, ligand-free metal salt catalytic system for preparing organoboron compounds by utilizing metal salts to catalyze the hydroboration of olefins. This catalytic system offers advantages such as readily available, environmentally friendly raw materials, mild reaction conditions, simple experimental procedures, and good functional group compatibility. Because organoboron compounds are among the most versatile intermediates in organic synthesis, their synthesis and application occupy a crucial position in organic chemistry. Therefore, the present invention possesses significant application value and socioeconomic benefits. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the hydrogen spectrum of 4,4,5,5-tetramethyl-2-(2-phenylethyl)-1,3,2-dioxaborane of Example 1;
[0022] Figure 2 This is the carbon spectrum of 4,4,5,5-tetramethyl-2-(2-phenylethyl)-1,3,2-dioxaborane of Example 1;
[0023] Figure 3 This is the hydrogen spectrum of 4,4,5,5-tetramethyl-2-(2-naphthylethyl)-1,3,2-dioxaborane of Example 2;
[0024] Figure 4 This is the carbon spectrum of 4,4,5,5-tetramethyl-2-(2-naphthylethyl)-1,3,2-dioxaborane of Example 2;
[0025] Figure 5 This is the hydrogen spectrum of 4,4,5,5-tetramethyl-2-(4-chlorophenethyl)-1,3,2-dioxaborane of Example 3;
[0026] Figure 6 This is the carbon spectrum of Example 3 4,4,5,5-tetramethyl-2-(4-chlorophenethyl)-1,3,2-dioxaborane. DETAILED DESCRIPTION
[0027] The present invention is further described below with reference to the embodiments:
[0028] Example 1
[0029] This embodiment discloses a synthesis of 4,4,5,5-tetramethyl-2-(2-phenylethyl)-1,3,2-dioxaborane, comprising the following steps:
[0030] Accurately weighed manganese chloride catalyst (16.19 mg, 0.1 mmol) and potassium tert-butoxide (134.7 mg, 1.2 mmol) were sequentially added to a Schlenk reaction tube equipped with a magnet. The reactor was purged with nitrogen three times. Styrene (104.2 mg, 1 mmol), bipyralidoboronic acid pinacol ester (761.82 mg, 3 mmol), and toluene (5 mL) were then added sequentially to the Schlenk reaction tube under nitrogen flow. The tube was then placed on a magnetic stirrer at 60°C for 12 hours. After the reaction, the reactor was slowly cooled to room temperature, and the solvent was removed under reduced pressure. Separation was performed on a silica gel column using petroleum ether / ethyl acetate as the eluent. The yield of 4,4,5,5-tetramethyl-2-(2-phenylethyl)-1,3,2-dioxaborane was 86%.
[0031] The hydrogen spectrum, carbon spectrum and infrared spectrum of 4,5,5-tetramethyl-2-(2-phenylethyl)-1,3,2-dioxaborane are as follows: Figure 1 and Figure 2 shown. 1 H NMR (400MHz, CDCl3): 7.19-7.05 (m, 5H), 2.71-2.63 (m, 2H), 1.15 (s, 12H), 1.11-1.04 (m, 2H); 13 C NMR (133MHz, CDCl3): 144.4, 128.2, 128.0, 125.5, 83.1, 29.9, 24.8, 12.8.
[0032] Example 2
[0033] This embodiment discloses a synthesis of 4,4,5,5-tetramethyl-2-(2-naphthylethyl)-1,3,2-dioxaborane, comprising the following steps:
[0034] Accurately weighed copper chloride catalyst (40.34 mg, 0.3 mmol) and potassium bromide (59.50 mg, 5 mmol) were sequentially added to a Schlenk reaction tube equipped with a magnet. The reactor was purged with nitrogen three times. 2-naphthylethylene (154.21 mg, 1 mmol), pinacol borane (511.92 mg, 4 mmol), and tetrahydrofuran (15 mL) were then added sequentially to the Schlenk reaction tube under nitrogen flow. The tube was then placed on a magnetic stirrer at 80°C for 24 hours. After the reaction, the reactor was slowly cooled to room temperature, and the solvent was removed under reduced pressure. Separation was performed on a silica gel column using petroleum ether / ethyl acetate as the eluent. The yield of 4,4,5,5-tetramethyl-2-(2-naphthylethyl)-1,3,2-dioxaborane was 73%.
[0035] The hydrogen spectrum and carbon spectrum of 4,4,5,5-tetramethyl-2-(2-naphthylethyl)-1,3,2-dioxaborane are as follows: Figure 3 and Figure 4 shown. 1 H NMR (400MHz, CDCl3): 7.79-7.73 (m, 3H), 7.64 (s, 1H), 7.43-7.36 (m, 3H), 2.91 (t, J=5.6Hz, 2H), 1.25-1.21 (m, 14H). 13 C NMR (133MHz, CDCl3): 142.0, 133.6, 131.9, 127.7, 127.5, 127.4, 127.3, 125.69, 125.66, 124.9, 83.1, 30.1, 24.8.
[0036] Example 3
[0037] This embodiment discloses a synthesis of 4,4,5,5-tetramethyl-2-(4-chlorophenethyl)-1,3,2-dioxaborane, comprising the following steps:
[0038] Accurately weighed manganese carbonate catalyst (57.48 mg, 0.5 mmol) and sodium chloride (46.75 mg, 8 mmol) were sequentially added to a Schlenk reaction tube equipped with a magnet. The reactor was purged with nitrogen three times. 4-Chlorostyrene (138.59 mg, 1 mmol), pinacol borane (1279.8 mg, 10 mmol), and 1,4-dioxane (10 mL) were then added sequentially to the Schlenk reaction tube under nitrogen. The tube was then stirred at 120°C on a magnetic stirrer for 30 hours. After the reaction, the reactor was slowly cooled to room temperature, and the solvent was removed under reduced pressure. Separation was performed on a silica gel column using petroleum ether / ethyl acetate as the eluent. The yield of 4,4,5,5-tetramethyl-2-(4-chlorophenethyl)-1,3,2-dioxaborane was 68%.
[0039] The hydrogen spectrum and carbon spectrum of 4,4,5,5-tetramethyl-2-(4-chlorophenethyl)-1,3,2-dioxaborane are as follows: Figure 5 and Figure 6 shown. 1 H NMR (400MHz, CDCl3): 7.21 (d, J=5.6Hz, 2H), 7.14d, J=5.6Hz, 2H), 2.71 (t, J=5.2Hz, 2H), 1.21 (s, 12H), 1.11 (t, J=5.2Hz, 2H). 13 C NMR (133MHz, CDCl3): 142.8, 131.1, 129.4, 128.2, 83.2, 29.3, 24.8, 12.8.
[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing an organoboron compound, characterized in that: The steps include: adding the catalyst and the additive into the Schleck reaction tube with the magnet in sequence, replacing the reactor with nitrogen three times, and replacing R 1 Substituted styrene, solvent and boron compound were added to the Schlenk reaction tube in sequence and placed on a magnetic stirrer for reaction. In the absence of an external ligand, R 1 The organoboron compound is prepared by anti-Markovnikov hydroboration reaction of substituted styrene and boron compound; The reaction equation is as follows: The R 1 Substitution of R on styrene 1 is selected from H or chlorine; R 1 in the ortho, meta or para position of the aromatic ring; The catalyst is selected from one or more of manganese chloride, copper chloride and copper acetate; The R 1 The molar ratio of substituted styrene to catalyst is 1:0.01 to 1:0.5; The solvent is selected from one or more of toluene, tetrahydrofuran, and 1,4-dioxane; The R 1 The molar content of substituted styrene in the solvent is 0.01 mmol / mL to 2 mmol / mL; The additive is selected from one or more of potassium tert-butoxide, sodium chloride, and potassium bromide; The boron compound is selected from pinacol borate or pinacol borane; The reaction temperature is 30-150° C., and the reaction time is 1-48 hours.
2. The method for preparing an organoboron compound according to claim 1, characterized in that: The R 1 The molar ratio of the substituted styrene to the additive is 1:0.2 to 1:
10.
3. The method for preparing an organoboron compound according to claim 1, characterized in that: The R 1 The molar ratio of the substituted styrene to the boron compound is 1:0.1 to 1:10.