A method for the synthesis of 1,6-dioxyalkene compounds by means of electrocatalysis
The method for synthesizing long-chain olefins by electrocatalysis solves the problems of unstable starting materials and harsh reaction conditions, and realizes a simple and efficient synthesis of olefins without metal catalysts, which is applicable to a wide range of applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2025-03-26
- Publication Date
- 2026-07-21
AI Technical Summary
Existing methods for synthesizing long-chain olefins often involve unstable starting materials, demanding reaction conditions, and poor selectivity.
An olefin compound was synthesized by electrocatalysis using carbon cloth as the anode and platinum sheet as the cathode, with arylbicyclopropane, tetrabutylammonium tetrafluoroborate and tris(4-bromophenyl)amine added in a nitrogen atmosphere and reacted under a constant current.
The reaction system is simple, requires no metal catalyst, has stable substrates, and is widely applicable. It can prepare a series of olefin compounds. Tris(4-bromophenyl)amine acts as an indirect oxidant to promote the ring-opening of cyclopropane, and the electrocatalytic method is unique.
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Figure CN120193287B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic chemistry, and specifically relates to a method for synthesizing 1,6-dioxanene compounds. Background Technology
[0002] Long-chain olefins are widely found in natural products, advanced materials, and precursor compounds for drug and agrochemical research. Because they serve as important building blocks or intermediates in small molecule synthesis, they are of significant value in organic synthetic chemistry research, antiviral drug development, and advanced material preparation. Therefore, the preparation and application of long-chain olefins continue to be explored in depth.
[0003] Currently, the preparation of long-chain olefin compounds mainly relies on the reaction of propyltriphenylphosphine bromide with acetone, or the conversion from other alkenes or alkynes. For example, in the method disclosed in Reference 1 (Ainai.T., Matsumi.M., Kobayashi.Y. J.O.R. G. Chem. 2003, 68, 7825-7832.), the reaction of propyltriphenylphosphine bromide with acetone can generate long-chain olefin compounds. The specific reaction process is shown below:
[0004]
[0005] The method disclosed in Reference 2 (Maestri. G, Maestri. M. ChemCatChem. 2015, 7, 3266-3269.) is a simple catalytic method that uses all metal aromatic skeletons as pre-catalysts, ensuring an efficient route to alkenes. Aromatic triangular palladium clusters are used to reduce internal alkynes, yielding alkenes without the formation of any alkane byproducts. The specific reaction process is as follows:
[0006]
[0007] The method disclosed in Reference 3 (Pan.CK., Xu.Y., Zhang.C. Cell Reports Physical Science. 2023, 4, 101233.) utilizes vinylcyclopropane to obtain aryl olefin compounds through a photoredox catalytic reaction with copper(II)-mediated free radicals. The specific reaction process is as follows:
[0008] Summary of the Invention
[0009] The purpose of this invention is to provide a green and efficient method for synthesizing olefin compounds, which solves the problems of high and unstable starting materials, harsh reaction conditions, and poor selectivity in existing synthesis methods through electrocatalysis.
[0010] To solve the technical problem of this invention, the proposed technical solution is: a method for synthesizing olefin compounds by electrocatalysis, comprising the following steps:
[0011] Step 1: Using carbon cloth as the anode and platinum sheet as the cathode and fix it, add arylbicyclopropane A, tetrabutylammonium tetrafluoroborate, ultra-dry acetonitrile and alcohol B, tris(4-bromophenyl)amine to a sealed 25mL reaction flask and place it in a nitrogen atmosphere;
[0012] Step 2: Under a constant current of 10mA, react in an oil bath at 45℃ until the arylbicyclopropane feedstock is completely consumed, then stop the reaction and cool to room temperature;
[0013] Step 3: The filtrate was evaporated to dryness under low pressure using a rotary evaporator, and the crude product was separated by column chromatography to obtain 1,6-dioxanone compound C.
[0014] The specific reaction equation is as follows:
[0015]
[0016] Where R 1 The following groups are included: hydrogen, 4-methyl, 4-methoxy, 4-fluoro, 4-chloro, 4-bromo, 3-trifluoromethyl, 3-fluoro-4-methoxy, 3-chloro-4-methoxy, 3-bromo-4-methoxy, 2-bromo-4-methoxy, 3,4-dimethoxy, 4-benzyloxy, 4-phenoxy, 2-methoxy, etc.; R 2 It can be a methyl, ethyl, propyl, butyl, hexyl, hydroxyethyl, or other similar group; R 3 For methyl, phenyl; R 4 It consists of methyl and hydrogen.
[0017] Preferably, the arylcyclopropane is selected from (2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl) aryl ring or 2,2′-diaryl-1,1′-bis(cyclopropane).
[0018] Preferably, the alcohol is selected from methanol, ethanol, propanol, butanol, hexanol, and ethylene glycol.
[0019] Preferably, the electrolyte is tetrabutylammonium tetrafluoroborate, the solvent is ultra-dry acetonitrile, B is an alcohol, and the oxidant is tris(4-bromophenyl)amine.
[0020] Preferably, the reaction temperature is 45°C and the reaction time is 50 min to 10 h.
[0021] Preferably, the solvent is ultra-dry acetonitrile and alcohol in a ratio of 1:4.
[0022] Preferably, the molar ratio of the reaction is raw material A: tetrabutylammonium tetrafluoroborate: tris(4-bromophenyl)amine: = 1.0: 1.0: 0.3.
[0023] The specific implementation scheme of the present invention is as follows:
[0024] Step 1: Using carbon cloth as the anode and platinum sheet as the cathode and fix it, add arylbicyclopropane A (1 equiv., 0.2 mmol), tetrabutylammonium tetrafluoroborate (1 equiv., 0.2 mmol), and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) to a 25 mL reaction flask and place it in a nitrogen atmosphere;
[0025]
[0026] Step 2: Add ultra-dry acetonitrile (1 ml) and alcohol B (4 ml), insert a nitrogen balloon, and react in an oil bath at 45°C under a constant current of 10 mA. Stop the reaction when the arylbicyclopropane raw material is consumed and cool to room temperature.
[0027] Step 3: The filtrate was evaporated to dryness under low pressure using a rotary evaporator, and the crude product was separated by column chromatography to obtain 1,6-dioxanone compound C.
[0028]
[0029] R in A and C 1 It consists of groups such as hydrogen, 4-methyl, 4-methoxy, 4-fluoro, 4-chloro, 4-bromo, 3-trifluoromethyl, 3-fluoro-4-methoxy, 3-chloro-4-methoxy, 3-bromo-4-methoxy, 2-bromo-4-methoxy, 3,4-dimethoxy, 4-benzyloxy, 4-phenoxy, and 2-methoxy.
[0030] R in C 2 These include groups such as methyl, ethyl, propyl, butyl, hexyl, and hydroxyethyl.
[0031] R in A and C 3 R 4 It can be: methyl, phenyl, or hydrogen.
[0032] In step two, the reaction is monitored by a TLC plate, and the reaction time is 50 min to 10 h.
[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0034] 1. The reaction system of the present invention is simple, no metal catalyst is required in the reaction, and the selected substrate is stable;
[0035] 2. The method used in this invention has wide applicability; most common chain alcohols are applicable to this method, and the substrates are widely applicable. A series of olefin compounds can be prepared according to this method.
[0036] 3. The main role of the additive tris(4-bromophenyl)amine in this reaction is as an indirect oxidizing agent, promoting the ring-opening of cyclopropane;
[0037] 4. The electrocatalytic method used in this invention has been screened and proven to be unique in this reaction. Attached Figure Description
[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0039] Figure 1 The nuclear magnetic resonance (NMR) of 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene provided in Example 1 of this invention. 1 H spectrum;
[0040] Figure 2 The nuclear magnetic resonance (NMR) of 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene provided in Example 1 of this invention. 13 C spectrum;
[0041] Figure 3 The nuclear magnetic resonance of 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene provided in Example 2 of this invention. 1 H spectrum;
[0042] Figure 4 The nuclear magnetic resonance of 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene provided in Example 2 of this invention. 13 C spectrum;
[0043] Figure 5 The nuclear magnetic resonance (NMR) of (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene provided in Example 3 of this invention. 1 H spectrum;
[0044] Figure 6 The nuclear magnetic resonance (NMR) of (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene provided in Example 3 of this invention. 13 C-spectrum. Detailed Implementation
[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0046] The method of this invention can synthesize 1,6-dioxanene compounds with different structures through the same mechanism, depending on the structure of the reaction substrate.
[0047] (1) Using 1-(2′,2′-dimethyl-[1,1′-bicyclopropane]-2-yl)-4-methoxybenzene as the template substrate, the practicality of the method is discussed using different types of alcohols. The specific reaction equations are as follows:
[0048]
[0049] Among them, R 2 It consists of groups such as methyl, ethyl, and hydroxyethyl. Its structural formula is as follows:
[0050]
[0051] (2) Using 2,2′-bis(4-methoxyphenyl)-1,1′-bis(cyclopropane) as the template substrate, the practicality of the method was discussed using alcohols with different structures. The specific reaction equations are as follows:
[0052]
[0053] Among them, R 2 These groups include methyl, ethyl, propyl, butyl, and hexyl groups. Their structural formulas are as follows:
[0054]
[0055] (3) Using methanol as a template substrate, the practicality of the method was discussed using arylcyclopropanes with different substituents. The specific reaction equations are as follows:
[0056]
[0057] Among them, R 1 The groups include: hydrogen, 4-methyl, 4-methoxy, 4-fluoro, 4-chloro, 4-bromo, 3-trifluoromethyl, 3-fluoro-4-methoxy, 3-chloro-4-methoxy, 3-bromo-4-methoxy, 2-bromo-4-methoxy, 3,4-dimethoxy, 4-benzyloxy, 4-phenoxy, and 2-methoxy groups. Its structural formula is as follows:
[0058]
[0059] Example 1
[0060] This embodiment describes the preparation of 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene, and the specific operations are as follows:
[0061]
[0062] Using carbon cloth as the anode and a platinum sheet as the cathode and fixed in place, 1-(2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl)-4-methoxybenzene (1 equiv., 0.2 mmol), tetrabutylammonium tetrafluoroborate (1 equiv., 0.2 mmol), and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) were added to a 25 mL reaction flask and placed under a nitrogen atmosphere. Ultra-dry acetonitrile (1 mL) and methanol (4 mL) were then added, and a nitrogen balloon was inserted. The reaction was carried out in an oil bath at 45 °C under a constant current of 10 mA. The reaction was stopped when the arylbiscyclopropane starting material was completely consumed, and the mixture was cooled to room temperature. The filtrate was evaporated to dryness under low pressure using a rotary evaporator. The crude product was separated by column chromatography (EA / PE = 1:50) to obtain 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene compound. The product was a colorless oily liquid with a yield of 73%.
[0063] The 1H NMR data for 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene are as follows: 1 HNMR (400MHz, Chloroform-d) δ7.19 (d, J=8.6Hz, 2H), 6.87 (d, J=8.6Hz, 2H), 5.48-5.31 (m, 2H), 4.06 (t, J=6.8Hz, 1H), 3. 80 (s, 3H), 3.18 (s, 3H), 3.17 (s, 3H), 2.57-2.50 (m, 1H), 2.42-2.29 (m, 1H), 2.13 (d, J=6.0Hz, 2H), 1.06 (d, J=1.6Hz, 6H).
[0064] The carbon NMR data for 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene are as follows: 13 CNMR (101MHz, Chloroform-d) δ159.0, 133.7, 129.0, 128.4, 128.0, 113.6, 83.6, 74.7, 56.3, 55.2, 49.1, 42.9, 41.2, 24.7.
[0065] Example 2
[0066] This example demonstrates the preparation of 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene, with the specific procedures as follows:
[0067]
[0068] Using carbon cloth as the anode and a platinum sheet as the cathode, 2,2'-bis(4-methoxyphenyl)-1,1'-bis(cyclopropane) (1 equiv., 0.2 mmol), tetrabutylammonium tetrafluoroborate (1 equiv., 0.2 mmol), and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) were added to a 25 mL reaction flask under a nitrogen atmosphere. Ultra-dry acetonitrile (1 mL) and methanol (4 mL) were added, and a nitrogen balloon was inserted. The reaction was carried out in an oil bath at 45 °C under a constant current of 10 mA. The reaction was stopped when the arylbiscyclopropane starting material was completely consumed, and the mixture was cooled to room temperature. The filtrate was evaporated to dryness under low pressure using a rotary evaporator. The crude product was separated by column chromatography (EA / PE = 3:100) to obtain 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene, a colorless oily liquid with a yield of 71%.
[0069] The 1H NMR data for 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene are as follows: 1 HNMR (400MHz, Chloroform-d) δ7.17-7.11(m, 4H), 6.89-6.84(m, 4H), 5.37-5.31(m, 2H), 4.00(q, J=6.7Hz, 2H), 3.81 (d, J=2.0Hz, 6H), 3.16 (d, J=2.4Hz, 6H), 2.52-2.43 (m, 2H), 2.33-2.24 (m, 2H).
[0070] The carbon NMR data for 1,6-dimethoxy-1,6-bis(4-methoxyphenyl)hex-3-ene are as follows: 13 CNMR (101MHz, Chloroform-d) δ159.0, 133.7, 133.7, 128.6, 128.0, 127.9, 113.6, 83.5, 56.3, 55.2, 41.2, 41.2.
[0071] Example 3
[0072] This embodiment demonstrates the preparation of (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene, and the specific operations are as follows:
[0073]
[0074] Using carbon cloth as the anode and a platinum sheet as the cathode and fixed, (2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl)benzene (1 equiv., 0.2 mmol), tetrabutylammonium tetrafluoroborate (1 equiv., 0.2 mmol), and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) were added to a 25 mL reaction flask and placed under a nitrogen atmosphere. Ultra-dry acetonitrile (1 mL) and methanol (4 mL) were added, and a nitrogen balloon was inserted. The reaction was carried out in an oil bath at 45 °C under a constant current of 10 mA. The reaction was stopped when the arylbicyclopropane starting material was completely consumed, and the mixture was cooled to room temperature. The filtrate was evaporated to dryness under low pressure using a rotary evaporator. The crude product was separated by column chromatography (2% EA / PE) to obtain (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene, a colorless oily liquid with a yield of 60%.
[0075] The 1H NMR spectral data of (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene are as follows: 1 H NMR (400MHz, Chloroform-d) δ7.35-7.30 (m, 2H), 7.28-7.23 (m, 3H), 5.54-5.25 (m, 2H), 4.11 (t, J=6.7Hz, 1H), 3.20 (s, 3H), 3.16 (s, 3H), 2.57-2.50 (m, 1H), 2.40-2.34 (m, 1H), 2.12 (d, J = 6.1Hz, 2H), 1.05 (d, J = 1.8Hz, 6H).
[0076] The carbon NMR spectral data of (1,6-dimethoxy-6-methylhept-3-en-1-yl)benzene are as follows: 13 C NMR (101MHz, Chloroform-d) δ141.7, 128.9, 128.6, 128.3, 128.3, 127.5, 126.8, 84.1, 77.3, 77.0, 76.7, 74.7, 56.6, 49.2, 43.0, 41.3, 24.7.
[0077] Comparative Example 1
[0078]
[0079] This comparative example is compared with Example 1: the preparation of 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene. The specific operation steps are as follows:
[0080] Using carbon cloth as the anode and a platinum sheet as the cathode and fixed in place, 1-(2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl)-4-methoxybenzene (1 equiv., 0.2 mmol), tetrabutylammonium tetrafluoroborate (1 equiv., 0.2 mmol), and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) were added to a 25 mL reaction flask and placed under a nitrogen atmosphere. Then, ultra-dry acetonitrile (1 mL) and methanol (4 mL) were added, a nitrogen balloon was inserted, and the reaction was carried out in an oil bath at 45 °C for 50 min without electricity. No product was observed to form.
[0081] Comparative Example 2
[0082] This comparative example is compared with Example 1: the preparation of 1-(1,6-dimethoxy-6-methylhept-3-en-1-yl)-4-methoxybenzene. The specific operation steps are as follows:
[0083]
[0084] Using carbon cloth as the anode and a platinum sheet as the cathode, 1-(2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl)-4-methoxybenzene (1 equiv., 0.2 mmol) and tris(4-bromophenyl)amine (0.3 equiv., 0.06 mmol) were added to a 25 mL reaction flask and placed under a nitrogen atmosphere. Then, ultra-dry acetonitrile (1 mL) and methanol (4 mL) were added, and a nitrogen balloon was inserted. After reacting for 50 min in an oil bath at 45 °C under a constant current of 10 mA, no product was observed to form.
[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for synthesizing 1,6-dioxanene compounds by electrocatalysis, characterized in that: Includes the following steps: Step 1: Using carbon cloth as the anode and platinum sheet as the cathode and fix it, add arylbicyclopropane A, tetrabutylammonium tetrafluoroborate, ultra-dry acetonitrile and alcohol B, tris(4-bromophenyl)amine to a sealed 25mL reaction flask and place it in a nitrogen atmosphere; Step 2: Under a constant current of 10mA, react in an oil bath at 45℃ until the arylbicyclopropane feedstock is completely consumed, then stop the reaction and cool to room temperature; Step 3: The filtrate was evaporated to dryness under low pressure using a rotary evaporator, and the crude product was separated by column chromatography to obtain 1,6-dioxanene compound C; The specific reaction equation is as follows: Where R 1 The following are: hydrogen, 4-methyl, 4-methoxy, 4-fluoro, 4-chloro, 4-bromo, 3-trifluoromethyl, 3-fluoro-4-methoxy, 3-chloro-4-methoxy, 3-bromo-4-methoxy, 2-bromo-4-methoxy, 3,4-dimethoxy, 4-benzyloxy, 4-phenoxy, 2-methoxy; R 2 The compounds are methyl, ethyl, propyl, butyl, hexyl, and hydroxyethyl. R 3 Methyl or phenyl; R 4 It consists of methyl and hydrogen.
2. The method for synthesizing 1,6-dioxanone compounds by electrocatalysis according to claim 1, characterized in that: The arylbicyclopropane A is selected from (2′,2′-dimethyl-[1,1′-bis(cyclopropane)]-2-yl) aryl ring or 2,2′-diaryl-1,1′-bis(cyclopropane).
3. The method for synthesizing 1,6-dioxanone compounds by electrocatalysis according to claim 1, characterized in that: The alcohol B is selected from methanol, ethanol, propanol, butanol, hexanol, and ethylene glycol.
4. The method for synthesizing 1,6-dioxanone compounds by electrocatalysis according to claim 1, characterized in that: The reaction temperature is 45°C, and the reaction time is 50 min to 10 h.
5. The method for synthesizing 1,6-dioxanene compounds by electrocatalysis according to claim 1, characterized in that: The reaction molar ratio of arylbicyclopropane A: tetrabutylammonium tetrafluoroborate: tris(4-bromophenyl)amine is 1.0:1.0:0.
3.
6. The method for synthesizing 1,6-dioxanene compounds by electrocatalysis according to claim 1, characterized in that: The ratio of ultra-dry acetonitrile to alcohol B is 1:4.