Method for synthesizing alkane by deoxidizing and reducing ether

Abstract

The invention discloses a method for synthesizing alkane by deoxidizing and reducing ether, which comprises the following steps: under the action of a catalyst, reacting an ether compound serving as a raw material with pinacolborane serving as a reducing agent in a solvent to obtain an alkane compound; the structural formula of the ether compound is # imgabs0 #; the alkane compound is as follows: # imgabs 1 #; wherein R1 is biphenyl, or 1-naphthyl, or 2-naphthyl, or 9-anthryl, or 4-methoxyphenyl, or tetrahydronaphthyl. The invention aims to provide the method which is wide in raw material source, easy to prepare, simple and convenient to operate and capable of synthesizing the alkane compound with high selectivity by taking various ether compounds as raw materials, and the reaction condition is mild.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and more particularly to a method for synthesizing alkanes by deoxygenation reduction of ethers. Background Art

[0002] Oxygen is the most widely distributed and abundant element in the earth's crust, and compounds containing CO bonds account for a very large proportion of organic compounds. Alcohols, ketones, and ether compounds are common organic compounds containing CO bonds. The transformation of CO bonds is also a very important reaction in organic synthesis, among which deoxygenation reduction is a very important transformation process, which is widely used in organic synthesis, pharmaceuticals, and biomass conversion. Direct deoxygenation reduction of ether compounds usually uses transition metals as catalysts, such as cobalt (ACS Catal. 2024, 14, 4249−4264.), palladium (ACS Catal. 2016, 6,7834−7838.), ruthenium (Org. Chem. Front. 2022, 9, 1943–1954.), nickel (J. Am. Chem. Soc. 2017, 139, 6546−6549.), etc. However, these methods usually have problems such as complex catalyst structure, expensive catalysts, harsh reaction conditions, high reaction temperature and long reaction time. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for synthesizing alkane compounds from various ether compounds with high selectivity, which has a wide range of raw material sources, is easy to prepare, and is simple to operate, and has mild reaction conditions.

[0004] To achieve the above object, the present invention provides the following technical solutions: A method for synthesizing alkanes by deoxygenation reduction of ethers, The steps include: Under the action of a catalyst, an ether compound is used as a raw material and pinacol borane is used as a reducing agent to react in a solvent to obtain an alkane compound; The structural formula of the ether compound is: ; The alkane compound: ; Wherein R1 is biphenyl or 1-naphthyl or 2-naphthyl or 9-anthracenyl or 4-methoxyphenyl or tetrahydronaphthyl.

[0005] As a further improvement of the present invention, The catalyst is lutetium chloride and tris(pentafluorophenyl)borane.

[0006] As a further improvement of the present invention, The molar ratio of the ether compound, lutetium chloride, tri(pentafluorophenyl)borane and pinacol borane is 0.5-1.5:0.1-0.2:0.05-0.1:3-10.

[0007] As a further improvement of the present invention, The molar ratio of the ether compound, lutetium chloride, tri(pentafluorophenyl)borane and pinacol borane is 1.0:0.1:0.05:5.0.

[0008] As a further improvement of the present invention, The solvent is 1,4-dioxane.

[0009] As a further improvement of the present invention, The above reaction is carried out under a protective gas atmosphere.

[0010] As a further improvement of the present invention, The protective gas is nitrogen.

[0011] As a further improvement of the present invention, The reaction temperature is room temperature.

[0012] As a further improvement of the present invention, The reaction time is 10~20h.

[0013] As a further improvement of the present invention, The method also includes obtaining alkane compounds by column chromatography after the reaction is completed.

[0014] The reaction equation is as follows:

[0015] The inventors have found a method for synthesizing alkanes by a method for efficiently realizing the deoxygenation reduction of ethers through in-depth and meticulous research. Under the co-catalytic system of lutetium chloride and tri(pentafluorophenyl)borane, ether compounds and pinacol borane undergo a deoxygenation reduction reaction, thereby realizing the synthesis of structurally diverse alkane compounds. This method has a wide range of raw material sources, is easy to operate, has wide universality, and has high selectivity. Compared with previous methods, chemical selectivity and environmental protection are significantly improved, which is difficult to achieve with other methods. The present invention has the following advantages and innovations: (1) The reaction has good universality and the yield of the product is high.

[0016] (2) This is an important supplement to the direct deoxygenation of ether compounds to prepare alkane compounds, and provides important ideas for organic synthesis, pharmaceutical engineering and biomass conversion synthesis.

[0017] (3) The catalytic conditions used in the method of the present invention are the simplest method for direct deoxygenation reduction of ether compounds to alkane compounds, which has obvious advantages over other complex catalytic systems.

[0018] (4) For the first time, pinacol borane was used as a reducing agent to achieve the deoxygenation reduction reaction of ether.

[0019] The beneficial effects of the present invention compared with the prior art are as follows: The alkane compounds prepared by the method of the present invention have high yield and good substrate universality. The reducing agent used is pinacol borane, which has obvious price advantages compared with commonly used reducing agents such as silane reducing agents. DETAILED DESCRIPTION

[0020] The present invention will be further described below by way of examples, but the examples do not limit the protection scope of the present invention. Example 1

[0021] Preparation of 4-methyl-1,1'-biphenyl, the structural formula is as follows:

[0022] Under nitrogen atmosphere, 0.4 mmol of raw material bis(biphenyl)methyl ether, catalysts lutetium chloride (0.04 mmol) and tri(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 91%.

[0023] 1 H NMR (400 MHz, CDCl3) δ 7.75 (dd, J = 8.1, 0.9 Hz, 2H), 7.67 (d, J = 8.1Hz, 2H), 7.58 (t, J = 7.6 Hz, 2H), 7.48 (t, J = 7.4 Hz, 1H), 7.41 (d, J = 7.9 Hz,2H), 2.56 (s, 3H). 13 C NMR (126 MHz, CDCl3) δ 141.3, 138.5, 137.1, 129.6, 128.8,127.1 (d, J = 3.0 Hz), 21.2. Example 2

[0024] The preparation of 1-methylnaphthalene has the following structural formula:

[0025] Under nitrogen atmosphere, 0.4 mmol of raw material bis-1-naphthylmethyl ether, catalysts lutetium chloride (0.04 mmol) and tri(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 83%.

[0026] 1 H NMR (400 MHz, CDCl3) δ 8.08 (d, J = 8.3 Hz, 1H), 7.96–7.89 (m, 1H),7.79 (d, J = 8.1 Hz, 1H), 7.63–7.53 (m, 2H), 7.49–7.38 (m, 2H), 2.78 (s, 3H). 13 CNMR(126 MHz, CDCl3) δ 134.4, 133.7, 132.7, 128.6, 126.7, 126.5, 125.8, 125.7,124.2, 19.5. Example 3

[0027] The preparation of 2-methylnaphthalene has the following structural formula:

[0028] Under nitrogen atmosphere, 0.4 mmol of raw material bis(2-naphthylmethyl ether), catalysts lutetium chloride (0.04 mmol) and tri(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 74%.

[0029] 1 H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 7.7 Hz, 1H), 7.80 (dd, J = 7.9, 3.8Hz, 2H), 7.66 (s, 1H), 7.52–7.42 (m, 2H), 7.36 (dd, J = 8.4, 1.4 Hz, 1H), 2.56(s, 3H). 13C NMR (126 MHz, CDCl3) δ 135.6, 133.8, 131.8, 128.2, 127.8, 127.7,127.4, 127.0, 126.0, 125.1, 21.8. Example 4

[0030] The preparation of 9-methylanthracene has the following structural formula:

[0031] Under nitrogen atmosphere, 0.4 mmol of raw material bis-9-methylanthryl ether, catalysts lutetium chloride (0.04 mmol) and tris(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 94%.

[0032] 1 H NMR (400 MHz, CDCl3) δ 8.37 (s, 1H), 8.32 (d, J = 9.2 Hz, 2H), 8.04(d, J = 7.4 Hz, 2H), 7.57-7.48 (m, 5H), 3.14 (s, 3H). 13 C NMR (126 MHz, CDCl3) δ131.5, 130.2, 129.1, 125.3, 125.3, 124.8, 124.7, 13.9. Example 5

[0033] Preparation of 1-methoxy-4-methylbenzene, the structural formula is as follows:

[0034] Under nitrogen atmosphere, 0.4 mmol of raw material 4,4'-(oxybis(methylene))bis(methoxybenzene), catalysts lutetium chloride (0.04 mmol) and tri(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 63%.

[0035] 1 H NMR (400 MHz, CDCl3) δ 7.13 (d, J = 8.1 Hz, 2H), 6.85 (d, J= 8.3 Hz,2H), 3.82 (s, 3H), 2.33 (s, 3H). 13 C NMR(126 MHz, CDCl3) δ 157.6, 130.0, 129.9,113.8, 55.4, 20.6. Example 6

[0036] The preparation of 1,2,3,4-tetrahydronaphthalene has the following structural formula:

[0037] Under nitrogen atmosphere, 0.4 mmol of raw material 1,1'-oxybis(1,2,3,4-tetrahydronaphthalene), catalysts lutetium chloride (0.04 mmol) and tri(pentafluorophenyl)borane (0.02 mmol), pinacol borane (2.0 mmol), and 1,4-dioxane (1 mL) were added and reacted at room temperature for 12 hours. The product was separated by column chromatography with a yield of 76%.

[0038] 1 H NMR (400 MHz, CDCl3) δ 7.13-7.07 (m, 4H), 2.79 (t, J = 6.7 Hz, 4H),1.83 (q, J = 3.4 Hz, 4H). 13 C NMR(126 MHz, CDCl3) δ 137.6, 129.6, 125.8, 29.8,23.7. Raw materials list raw material factory Lutetium chloride Shanghai Jinjinle Industrial Co., Ltd. Tris(pentafluorophenyl)borane Hubei Jusheng Technology Co., Ltd. Pinacol borane Shanghai Jinjinle Industrial Co., Ltd. 1,4-Dioxane Shanghai Jinjinle Industrial Co., Ltd. Bis(biphenyl)methyl ether Laboratory synthesis, reference 2014,, 3765-3767 Bis-1-naphthylmethyl ether Hubei Yongkuo Technology Co., Ltd. Bis-2-naphthylmethyl ether Shanghai Darui Fine Chemicals Co., Ltd. Bis-9-methylanthryl ether Laboratory synthesis, reference 2014,, 3765-3767 4,4'-(oxybis(methylene))bis(methoxybenzene) Laboratory synthesis, reference 2014,, 3765-3767 1,1'-Oxybis(1,2,3,4-tetrahydronaphthalene) Laboratory synthesis, reference 2014,, 3765-3767 The inventors have found a method for synthesizing alkanes by a method for efficiently realizing the deoxygenation reduction of ethers through in-depth and meticulous research. Under the co-catalytic system of lutetium chloride and tri(pentafluorophenyl)borane, ether compounds and pinacol borane undergo a deoxygenation reduction reaction, thereby realizing the synthesis of structurally diverse alkane compounds. This method has a wide range of raw material sources, is easy to operate, has wide universality, and has high selectivity. Compared with previous methods, chemical selectivity and environmental protection are significantly improved, which is difficult to achieve with other methods. The present invention has the following advantages and innovations: (1) The reaction has good universality and the yield of the product is high.

[0039] (2) This is an important supplement to the direct deoxygenation of ether compounds to prepare alkane compounds, and provides important ideas for organic synthesis, pharmaceutical engineering and biomass conversion synthesis.

[0040] (3) The catalytic conditions used in the method of the present invention are the simplest method for direct deoxygenation reduction of ether compounds to alkane compounds, which has obvious advantages over other complex catalytic systems.

[0041] (4) For the first time, pinacol borane was used as a reducing agent to achieve the deoxygenation reduction reaction of ether.

[0042] The beneficial effects of the present invention compared with the prior art are as follows: The alkane compounds prepared by the method of the present invention have high yield and good substrate universality. The reducing agent used is pinacol borane, which has obvious price advantages compared with commonly used reducing agents such as silane reducing agents.

[0043] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing alkanes by deoxidation reduction of ethers, characterized in that: The steps include: Under the action of a catalyst, an ether compound is used as a raw material and pinacol borane is used as a reducing agent to react in a solvent to obtain an alkane compound; The structural formula of the ether compound is: ； The alkane compound: ； Wherein R1 is biphenyl or 1-naphthyl or 2-naphthyl or 9-anthracenyl or 4-methoxyphenyl or tetrahydronaphthyl.

2. The method for synthesizing alkanes by deoxygenation reduction of ethers according to claim 1, characterized in that: The catalyst is lutetium chloride and tris(pentafluorophenyl)borane.

3. The method for synthesizing alkanes by deoxidation reduction of ethers according to claim 2, characterized in that: The molar ratio of the ether compound, lutetium chloride, tri(pentafluorophenyl)borane and pinacol borane is 0.5-1.5:0.1-0.2:0.05-0.1:3-10.

4. The method for synthesizing alkanes by deoxidation reduction of ethers according to claim 2, characterized in that: The molar ratio of the ether compound, lutetium chloride, tri(pentafluorophenyl)borane and pinacol borane is 1.0:0.1:0.05:5.

0.

5. The method for synthesizing alkanes by deoxidation reduction of ether according to claim 1, characterized in that: The solvent is 1,4-dioxane.

6. The method for synthesizing alkanes by deoxygenation reduction of ether according to claim 1, characterized in that: The above reaction is carried out under a protective gas atmosphere.

7. The method for synthesizing alkanes by deoxygenation reduction of ethers according to claim 6, characterized in that: The protective gas is nitrogen.

8. The method for synthesizing alkanes by deoxygenation reduction of ethers according to claim 1, characterized in that: The reaction temperature is room temperature.

9. The method for synthesizing alkanes by deoxygenation reduction of ethers according to claim 1, characterized in that: The reaction time is 10~20h.

10. The method for synthesizing alkanes by deoxygenation reduction of ether according to claim 1, characterized in that: The method also includes obtaining alkane compounds by column chromatography after the reaction is completed.

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