A method for electrocatalytic ring opening of furans to produce cis olefins

Abstract

The application discloses a method for preparing a cis olefin through electrocatalysis of furan ring opening, and (Z)-1-phenyl-2-ene-1,4-diketone compound L is obtained through electrocatalysis of furan ring opening for the first time. The ring opening step of the compound is simple, the raw material and technology are clean, only potassium carbonate is used as an electrolyte, anhydrous methanol is used as a raw material, the reaction yield is high, and the process system is highly green. In addition, the (Z)-1-phenyl-2-ene-1,4-diketone compound obtained through electrocatalysis has high application value in the fields of medicine, agriculture and material chemistry.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis, and more particularly to a clean technique for the electrocatalytic ring-opening of furan to prepare (Z)-1-phenyl-2-ene-1,4-dione compounds. Background Technology

[0002] 2-En-1,4-Dietone structures serve as multifunctional precursors for constructing various heterocycles such as thiophenes, pyrroles, pyrazines, and indoleazines. Furthermore, due to their unique electrophilicity, they have been used as highly reactive electrophiles and dienophiles to construct complex molecules. These unit structures are known to be required in the synthesis of many natural products, drugs, and synthetic intermediates, thus finding wide application in medicinal chemistry, agricultural science, and materials chemistry. However, their large-scale preparation has not been achieved due to the difficulty of their synthesis. Furans, as dienes, have been widely reported in Diels-Alder reactions and applied in various reaction systems; however, their stability is relatively poor in five-membered heterocyclic compounds.

[0003] There are relatively few literature reports on the ring-opening of furans. In the 1980s, it was reported that 2,3,5-trisubstituted furans were successfully ring-opened to cis-enide structures by m-chloroperoxybenzoic acid (m-CPBA) (yield 60-70%). However, excess m-CPBA will lead to Baeyer-Villiger oxidation, which will convert it to enol acetate (PDWilliams, E. LeGoff, Oxidation of Furans II. Use of furans as masked dienophiles in the intramolecular Diels-Alder reaction, Tetrahedron Letters, 26(11), 1367-1370, 1985). In the 1990s, B. Adger et al. discovered that dimethyl dioxyethylene (DMD) could achieve cis-ring opening of furan in acetone solution with a yield >95%. However, the large-scale use of DMD as a strong oxidant is extremely prone to causing flammable and explosive accidents (BMAdger, C. Barrett, J. Brennan, M. Anthony McKervey, RW Murray. Oxidation offurans with dimethyldioxirane. J. Chem. Soc., Chem. Commun., 1991, 1553-1554). Since then, the continuously developing electrochemical technology has gradually demonstrated its advantages in oxidation reactions, and its advancements have also provided new solutions to overcome the shortcomings of traditional preparation methods. Currently, electrochemistry is widely used in the oxidative conversion of ethanol, glycerol, benzyl alcohol, furfural, and HMF, forming a high-value-added clean conversion process. This patent will provide a safe, efficient, clean, energy-saving, and sustainable synthesis technology for (Z)-1-phenyl-2-en-1,4-dione compounds. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a clean process method for the electrocatalytic ring-opening conversion of furan in order to overcome the shortcomings of the prior art. The aim is to form a clean and safe preparation process for (Z)-1-phenyl-2-en-1,4-dione compounds, so as to innovate the green conversion of furan structures and overcome the problems of low safety in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0006] A method for the electrocatalytic ring-opening of furan to prepare cis-olefins, namely a clean technology for the electrocatalytic ring-opening of furan to prepare (Z)-1-phenyl-2-ene-1,4-dione compounds, includes the following steps:

[0007] (1) Compounds a1 and a2 were used to synthesize the electrocatalytic ring-opening starting material compound A;

[0008] (2) The ring-opening reaction of compound A was carried out by electrocatalysis to obtain compound L;

[0009]

[0010] in,

[0011] R1 is selected from alkyl groups, preferably C1-C10 alkyl groups, and more preferably methyl, ethyl, n-butyl, n-pentyl or n-heptyl, etc.

[0012] R2 is selected from hydrogen, alkyl, aldehyde, cyano, ketone, amino or carboxyl, preferably hydrogen, C1-C6 alkyl, aldehyde, cyano, ketone, amino or carboxyl, and more preferably hydrogen, methyl, ethyl, n-butyl, aldehyde, cyano, ketone, amino or carboxyl.

[0013] In step (1),

[0014] The molar ratio of compound a1 to compound a2 is 1.5-2.5:1, preferably 2:1.

[0015] In the reaction system, the concentration of compound a1 is 1-2 M, preferably 1.6 M.

[0016] The reaction system also includes tricyclohexylphosphine, tetrabutylammonium bromide, potassium acetate, and palladium chloride.

[0017] The reaction system also includes a solvent; the solvent is an organic solvent, preferably DMA.

[0018] The molar ratio of compound a1, tricyclohexylphosphine, tetrabutylammonium bromide, potassium acetate and palladium chloride is 1.5-2.5:0.05-0.15:1:1:0.05-0.15, preferably 2:0.1:1:1:0.05.

[0019] The reaction temperature is 100-120℃.

[0020] In step (2),

[0021] In the reaction system, the concentration of compound A is 0.01-0.1M, preferably 0.02M.

[0022] The ring-opening reaction includes an electrolyte; preferably, the electrolyte is any one or a combination of tetrabutylammonium bromide, tetramethylammonium bromide, potassium tert-butoxide, ammonium formate, potassium hydroxide, and potassium carbonate, preferably potassium carbonate; preferably, the concentration of the electrolyte in the reaction system is 0.01-0.3M, preferably 0.1M.

[0023] The ring-opening reaction includes a solvent; preferably, the solvent is any one or a combination of several of acetic acid, dimethyl sulfoxide, ethanol, methanol and water, preferably methanol.

[0024] The current for the open-loop reaction is 4-40 mA, preferably 4-20 mA, more preferably 4-12 mA, and more preferably 6 mA.

[0025] The working electrode of the electrocatalysis is any one of Zn electrode, Cu electrode, Ni electrode, Fe electrode, Au electrode and Pt electrode, preferably Pt electrode; the counter electrode of the electrocatalysis is any one of Cu electrode, Ag electrode, Pt electrode, Au electrode and graphite electrode, preferably graphite electrode.

[0026] The ring-opening reaction is carried out at a temperature of 20-30°C, preferably at room temperature.

[0027] The clean technology described in this invention specifically refers to electrochemical catalysis, which does not require transition metals or flammable and explosive oxidants, and the reaction conditions are mild, without the need for harsh conditions such as high temperature.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0029] (1) The electrocatalytic preparation method of (Z)-1-phenyl-2-ene-1,4-dione compounds provided in this invention uses substituted furan as raw material, methanol as solvent, potassium carbonate as electrolyte, and constant current of 4-40mA to carry out ring opening at room temperature. The reaction conditions are mild, the raw materials are cheap and readily available, and the product yield is high.

[0030] (2) The conversion method provided in this invention is simple to operate, applicable to a wide range of substrates, produces high added value products, is clean, and conforms to the concept of green and low-carbon.

[0031] (3) The product structure provided in this invention is specific and highly selective, effectively solving the problems of low selectivity in existing preparation methods.

[0032] (4) The (Z)-1-phenyl-2-ene-1,4-dione compounds obtained in this invention can meet the requirements of specific substrate structure configurations and effectively improve the efficiency of olefins participating in conversion.

[0033] (5) The preparation method provided in this invention is in-situ oxidation, the system is highly green, and the whole process is highly safe, which is in line with the concept of green and low carbon and has good application and promotion value. Detailed Implementation

[0034] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0035] Example 1 Compound L 11 Preparation

[0036] S1: Open-ring feedstock A 11 Preparation

[0037] Tricyclohexylphosphine (0.11 g, 0.4 mmol, 10 mol%), 2-ethylfuran (0.77 g, 8 mmol), bromobenzene (0.64 g, 4 mmol), tetrabutylammonium bromide (1.29 g, 4 mmol), potassium acetate (0.39 g, 4 mmol), and DMA (5 mL) were added sequentially to a reaction flask, followed by the addition of palladium chloride (0.035 g, 0.2 mmol, 5 mol%) under a nitrogen atmosphere. The reaction was stirred at 110 °C for 10 h, quenched with water, and the organic phase was extracted with ethyl acetate (15 mL × 3). After drying with anhydrous sodium sulfate, the residue was purified by rotary evaporation and silica gel column chromatography to obtain A. 11 (Colorless oily liquid, 0.54 g, yield, 78.38%).

[0038]

[0039] 1 H NMR (400MHz, CDCl3) δ7.62(d,J=7.3Hz,2H),7.33(t,J=7.8Hz,2H),7.19(t,J=7.4Hz,1H), 6.53(d,J=3.2Hz,1H), 6.04(d,J=3.2Hz,1H), 2.70(q,J=7.5Hz,2H), 1.26(t,J=7.6Hz,3H).

[0040] 13 C NMR (101MHz, CDCl3) δ157.67,152.14,131.26,128.59,126.73,123.34,106.08,105.64,21.54,12.23.

[0041] S2: Compound A 11 Electrocatalytic ring-opening preparation of compound L 11

[0042] Sequentially A 11 (0.3 mmol, 51.6 mg), methanol (15 mL), and anhydrous potassium carbonate (200 mg, 1.4 mmol) were added to an electrolytic cell with a Pt electrode at the anode and a graphite electrode at the cathode. The reaction was stirred for 9 h at a current of 6 mA, quenched with water, and the organic phase was extracted with dichloromethane (10 mL × 3). After drying with anhydrous sodium sulfate, L was obtained by thin-layer chromatography. 11(Yellow liquid, 39.7 mg, yield: 70.3%).

[0043]

[0044] 1 H NMR (400MHz, CDCl3) δ7.92-7.76(m,2H),7.56-7.43(m,1H),7.38(t,J=7.6Hz,2H),6.75 (d,J=12.0Hz,1H),6.50(d,J=12.0Hz,1H),2.49(q,J=7.2Hz,2H),0.99(t,J=7.2Hz,3H).

[0045] 13 C NMR (101MHz, CDCl3) δ202.21,193.65,135.95,135.91,135.47,133.62,128.76,128.58,35.93,7.48.

[0046] Example 2 Compound L 12 Preparation

[0047] S1: The experiment was conducted according to the method in S1 of Example 1, using an equimolar amount of 2-n-butylfuran to obtain A. 12 (Colorless oily liquid, 0.49 g, yield: 61.66%).

[0048]

[0049] 1 H NMR (400MHz, CDCl3) δ7.62(dd,J=8.3,1.1Hz,2H),7.34(t,J=7.8Hz,2H),7.20(ddd,J=8.6,2.1,0.8Hz,1H),6.53(d,J=3.2Hz,1H),6 .04(d,J=3.2Hz,1H),2.68(t,J=7.6Hz,2H),1.67(ddd,J=15.2,8.5,6.6Hz,2H),1.41(dq,J=14.6,7.4Hz,2H),0.94(t,J=7.4Hz,3H).

[0050] 13 C NMR (101MHz, CDCl3) δ156.50,152.14,131.33,128.63,126.74,123.36,106.87,105.68,30.28,27.92,22.34,13.89.

[0051] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 12 , obtain L 12 (Pale purple liquid, 44.9 mg, yield: 69.20%).

[0052]

[0053] 1 H NMR(400MHz, CDCl3) δ7.85(dd,J=5.2,3.3Hz,2H),7.54-7.47(m,1H),7.39(dd,J=10.5,4.7Hz,2H),6.75(d,J=12.0 Hz,1H),6.51(d,J=12.0Hz,1H),2.47(t,J=7.4Hz,2H),1.55-1.45(m,2H),1.29-1.16(m,2H),0.81(t,J=7.3Hz,3H).

[0054] 13 C NMR (101MHz, CDCl3) δ201.69,193.71,135.95,135.86,135.68,133.58,128.73,128.59,42.42,25.56,22.20,13.83.

[0055] HRMS-ESI + (m / z):C 14 H 17 O2[M+H] + calcd for 217.1223, found 217.1237.

[0056] Example 3 Compound L 13 Preparation

[0057] S1: The experiment was conducted according to the method in S1 of Example 1, using an equimolar amount of 2-n-n-pentylfuran to obtain A. 13 (0.52 g of colorless oily liquid, yield: 60.66%).

[0058]

[0059] 1H NMR (400MHz, CDCl3) δ7.62 (dd, J=8.2, 1.0Hz, 2H), 7.34 (t, J=7.8Hz, 2H), 7.19 (dd, J=10.5, 4.2Hz, 1H), 6.53 (d, J=3. 2Hz, 1H), 6.04 (d, J = 3.2Hz, 1H), 2.66 (t, J = 7.6Hz, 2H), 1.73-1.64 (m, 2H), 1.38-1.33 (m, 4H), 0.91 (t, J = 7.0Hz, 3H).

[0060] 13 C NMR (101MHz, CDCl3) δ156.53,152.12,131.31,128.61,126.73,123.35,106.85,105.67,31.44,28.19,27.83,22.47,14.05.

[0061] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 13 , obtain L 13 (Yellow liquid, 43.7 mg, yield: 63.25%).

[0062]

[0063] 1 H NMR (400MHz, CDCl3) δ7.88-7.83(m,2H),7.50(ddd,J=6.8,4.0,1.3Hz,1H),7.42-7.36(m,2H),6.74(d,J=12.0Hz ,1H),6.50(d,J=12.0Hz,1H),2.47(t,J=7.4Hz,2H),1.56-1.48(m,2H),1.25-1.15(m,4H),0.79(t,J=6.9Hz,3H).

[0064] 13 C NMR (101MHz, CDCl3) δ201.66,193.72,135.94,135.80,135.70,133.56,128.72,128.57,42.69,31.22,23.18,22.42,13.88.

[0065] HRMS-ESI + (m / z):C 15 H 18 KO2 [M+K] + calcd for 269.0938, found 269.0938.

[0066] Example 4 Compound L 21 Preparation

[0067] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-methylfuran and equimolar amounts of p-bromotoluene to obtain A. 21 (Colorless oily liquid, 0.37 g, yield: 53.71%).

[0068]

[0069] 1 H NMR (400MHz, CDCl3) δ7.51(d,J=8.2Hz,2H),7.15(d,J=8.0Hz,2H),6.46(d,J=3.2Hz,1H),6.02(d,J=2.3Hz,1H),2.35(s,3H),2.34(s,3H).

[0070] 13 C NMR (101MHz, CDCl3) δ152.55,151.54,136.53,129.32,128.58,123.32,107.60,105.11,21.27,13.75.

[0071] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 21 , obtain L 21 (Pale purple liquid, 42.3 mg, yield: 74.91%).

[0072]

[0073] 1 H NMR (400MHz, CDCl3) δ7.76(d,J=8.2Hz,2H),7.20(d,J=7.3Hz,2H),6.79(d,J=12.1Hz,1H),6.46(d,J=12.1Hz,1H),2.34(s,3H),2.20(s,3H).

[0074] 13 C NMR (101MHz, CDCl3) δ199.60,192.87,144.74,136.36,135.33,133.50,129.52,128.77,29.87,21.78.

[0075] HRMS-ESI + (m / z):C 12 H 12NaO2[M+Na] + calcd for 211.0730, found 211.0729.

[0076] Example 5 Compound L 22 Preparation

[0077] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-ethylfuran and equimolar amounts of p-bromotoluene to obtain A. 22 (Colorless oily liquid, 0.50 g, yield: 67.11%).

[0078]

[0079] 1 H NMR (400MHz, CDCl3) δ7.43(d,J=8.2Hz,2H),7.06(d,J=8.0Hz,2H),6.38(d,J=3.2Hz ,1H),5.94(d,J=3.2Hz,1H),2.65-2.56(m,2H),2.24(s,3H),1.18(t,J=7.6Hz,3H).

[0080] 13 C NMR (101MHz, CDCl3) δ157.25,152.42,136.50,129.31,128.68,126.86123.38,106.00,104.92,21.58,21.27,12.30.

[0081] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 22 , obtain L 22 (Pale purple liquid, 47.2 mg, yield: 77.79%).

[0082]

[0083] 1 H NMR (400MHz, CDCl3) δ7.76(d,J=8.2Hz,2H),7.19(d,J=8.0Hz,2H),6.76(d,J=12.0Hz, 1H), 6.48 (d, J = 12.0Hz, 1H), 2.50 (q, J = 7.2Hz, 2H), 2.34 (s, 3H), 1.01 (t, J = 7.2Hz, 3H).

[0084] 13C NMR (101MHz, CDCl3) δ202.39,193.06,144.60,135.92,135.30,133.53,129.48,128.75,35.92,21.76,7.51.

[0085] HRMS-ESI + (m / z):C 13 H 14 KO2 [M+K] + calcd for 241.0625, found 241.0643.

[0086] Example 6 Compound L 23 Preparation

[0087] S1: The experiment was conducted according to the method in S1 of Example 1, except that 2-methylfuran was replaced with an equimolar amount of 2-n-butylfuran and an equimolar amount of p-bromotoluene, to obtain A. 23 (Colorless oily liquid, 0.50 g, yield: 58.33%).

[0088]

[0089] 1 H NMR (400MHz, CDCl3) δ7.52(d,J=8.2Hz,2H),7.15(d,J=8.0Hz,2H),6.47(d,J=3.2Hz,1H),6.03(d,J=3.2Hz,1H ),2.67(t,J=7.6Hz,2H),2.34(s,3H),1.67(dt,J=15.2,7.5Hz,2H),1.47-1.35(m,2H),0.94(t,J=7.4Hz,3H).

[0090] 13 C NMR (101MHz, CDCl3) δ156.03,152.32,136.45,129.27,128.64,123.32,106.70,104.87,30.29,27.91,22.34,21.26,13.89

[0091] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 23 , obtain L 23 (Yellow liquid, 53.0 mg, yield: 76.71%).

[0092]

[0093] 1H NMR (400MHz, CDCl3) δ7.82(d,J=8.2Hz,2H),7.25(d,J=8.0Hz,2H),6.81(d,J=12.0Hz,1H),6.54(d,J=12.0Hz,1H),2 .54(t,J=7.4Hz,2H),2.40(s,3H),1.56(dd,J=15.1,7.6Hz,2H),1.30(dd,J=15.0,7.5Hz,2H),0.87(t,J=7.3Hz,3H).

[0094] 13 C NMR (101MHz, CDCl3) δ201.91,193.16,144.53,135.87,135.47,133.55,129.45,128.73,42.39,25.59,22.20,21.73,13.83.

[0095] HRMS-ESI + (m / z):C 15 H 18 NaO2[M+Na] + calcd for 253.1199, found 253.1189.

[0096] Example 7 Compound L 24 Preparation

[0097] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-pentylfuran and equimolar amounts of p-bromotoluene to obtain A. 24 (Colorless oily liquid, 0.37 g, yield: 40.51%).

[0098]

[0099] 1 H NMR (400MHz, CDCl3) δ7.52(d,J=8.2Hz,2H),7.15(d,J=8.0Hz,2H),6.47(d,J=3.2Hz,1H),6.03(d,J=3.2Hz, 1H),2.66(t,J=7.6Hz,2H),2.34(s,3H),1.69(dq,J=14.9,7.4Hz,2H),1.41-1.30(m,4H),0.96-0.83(m,3H).

[0100] 13C NMR (101MHz, CDCl3) δ156.08,152.33,136.46,129.28,128.66,123.33,106.70,104.88,31.44,28.18,27.85,22.47,21.25,14.05.

[0101] HRMS-ESI + (m / z):C 16 H 20 O[M] + calcd for 228.1514, found 228.1519.

[0102] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 24 , obtain L 24 (Yellow liquid, 60 mg, yield: 81.86%).

[0103]

[0104] 1 H NMR (400MHz, Chloroform-d) δ7.86-7.79(m,2H),7.26(d,J=6.6Hz,2H),6.81(d,J=12.0Hz,1H),6.54(d,J=12. 0Hz,1H),2.53(t,J=7.4Hz,2H),2.41(s,3H),1.59(p,J=7.4Hz,2H),1.31-1.20(m,4H),0.86(t,J=6.9Hz,3H).

[0105] 13 C NMR (101MHz, CDCl3) δ201.89,193.20,144.54,135.79,135.55,133.55,129.45,128.74,42.68,31.24,23.20,22.43,21.75,13.89.

[0106] HRMS-ESI + (m / z):C 16 H 21 O2[M+H] + calcd for 245.1536,found:245.1539.

[0107] Example 8 Compound L 25 Preparation

[0108] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-heptylfuran and equimolar amounts of p-bromotoluene to obtain A. 25 (Colorless oily liquid, 0.51 g, yield: 49.73%).

[0109]

[0110] 1 H NMR (400MHz, CDCl3) δ7.48-7.40(m,2H),7.08(d,J=7.9Hz,2H),6.39(d,J=3.2Hz,1H),5.94(t,J=5.1Hz ,1H),2.58(t,J=7.6Hz,2H),2.26(s,3H),1.66-1.55(m,2H),1.31-1.17(m,8H),0.81(t,J=6.9Hz,3H).

[0111] 13 C NMR (101MHz, CDCl3) δ156.09,152.33,136.45,129.28,128.67,123.33,106.69,104.88,31.83,29.23,29.10,28.22,28.17,22.70,21.25,14.13.

[0112] HRMS-ESI + (m / z):C 18 H 24 O[M] + calcd for 256.1827, found 256.1954.

[0113] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 25 , obtain L 25 (Yellow liquid, 66.8 mg, yield: 81.75%).

[0114]

[0115] 1 H NMR (400MHz, CDCl3) δ7.82(d,J=7.9Hz,2H),7.26(d,J=8.0Hz,2H),6.81(d,J=12.0Hz,1H),6.55(d,J=1 2.0Hz,1H),2.53(t,J=7.4Hz,2H),2.40(s,3H),1.64-1.53(m,2H),1.25(s,8H),0.86(t,J=6.6Hz,3H).

[0116] 13 C NMR (101MHz, CDCl3) δ201.92,193.24,144.55,135.80,135.58,133.54,129.47,128.75,42.73,31.66,29.05,23.52,22.61,21.76,14.08.

[0117] HRMS-ESI + (m / z):C 18 H 24 NaO2[M+Na] + calcd for 295.1669, found 295.1646.

[0118] Example 9 Compound L 31 Preparation

[0119] S1: The experiment was conducted according to the method in S1 of Example 1, using a molar amount of 4-ethylbromobenzene and an equimolar amount of 2-methylfuran to obtain A. 31 (Colorless oily liquid, 0.41 g, yield: 55.03%).

[0120]

[0121] 1 H NMR (400MHz, CDCl3) δ7.52(d,J=8.2Hz,2H),7.14(d,J=8.2Hz,2H),6.44(d,J=3.2Hz,1H) ,5.99(dd,J=3.0,0.7Hz,1H),2.60(q,J=7.6Hz,2H),2.31(s,3H),1.20(t,J=7.6Hz,3H).

[0122] 13 C NMR (101MHz, CDCl3) δ152.71,151.62,143.02,128.86,128.24,123.53,107.75,105.29,28.78,15.68,13.80.

[0123] HRMS-ESI + (m / z):C 13 H 14 O[M] + calcd for 186.1045,found 186.1039.

[0124] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 31 , obtain L 31 (Yellow liquid, 50.4 mg, yield: 83.07%).

[0125]

[0126] 1 H NMR (400MHz, CDCl3) δ7.86(d,J=8.2Hz,2H),7.29(d,J=8.2Hz,2H),6.86(d,J=12.1Hz, 1H), 6.53 (d, J = 12.1Hz, 1H), 2.70 (q, J = 7.6Hz, 2H), 2.27 (s, 3H), 1.25 (t, J = 7.6Hz, 3H).

[0127] 13 C NMR (101MHz, CDCl3) δ199.68,192.92,150.86,136.40,135.35,133.69,128.89,128.35,29.87,29.04,15.12.

[0128] HRMS-ESI + (m / z):C 13 H 15 O2[M+H] + calcd for 203.1067, found 203.1071.

[0129] Example 10 Compound L 32 Preparation

[0130] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-pentylfuran and equimolar amounts of 4-ethylbromobenzene to obtain A. 32 (Colorless oily liquid, 0.45 g, yield: 46.42%).

[0131]

[0132] 1H NMR (400MHz, CDCl3) δ7.54(d,J=8.2Hz,2H),7.18(d,J=8.3Hz,2H),6.48(d,J=3.2Hz,1H),6.02(t,J=5.1Hz,1H),2.6 4(dt,J=14.9,7.5Hz,4H),1.68(dq,J=14.9,7.4Hz,2H),1.40-1.32(m,4H),1.23(t,J=7.6Hz,3H),0.95-0.86(m,3H).

[0133] 13 C NMR (101MHz, CDCl3) δ156.08,152.32,142.88,128.88,128.07,123.39,106.68,104.90,31.42,28.65,28.17,27.83,22.45,15.57,14.04.

[0134] HRMS-ESI + (m / z):C 17 H 23 O[M+H] + calcd for 243.1744, found 243.1762.

[0135] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 32 , obtain L 32 (Yellow liquid, 64.5 mg, yield: 83.22%).

[0136]

[0137] 1 H NMR (400MHz, CDCl3) δ7.77(d,J=8.3Hz,2H),7.20(d,J=8.3Hz,2H),6.74(d,J=12.0Hz,1H),6.47(d,J=12.0Hz, 1H), 2.62 (q, J = 7.6Hz, 2H), 2.45 (t, J = 7.4Hz, 2H), 1.58-1.46 (m, 2H), 1.23-1.13 (m, 7H), 0.78 (t, J = 6.9Hz, 3H).

[0138] 13C NMR (101MHz, CDCl3) δ201.93,193.24,150.68,135.77,135.61,133.71,128.85,128.28,42.68,31.23,29.04,23.20,22.43,15.13,13.89.

[0139] HRMS-ESI + (m / z):C 17 H 22 KO2 [M+K] + calcd for 297.1251, found 297.1254

[0140] Example 11 Compound L 33 Preparation

[0141] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-heptylfuran and equimolar amounts of 4-ethylbromobenzene to obtain A. 33 (Colorless oily liquid, 0.48 g, yield: 44.38%).

[0142]

[0143] 1 H NMR (400MHz, CDCl3) δ7.54(d,J=8.2Hz,2H),7.17(d,J=8.2Hz,2H),6.47(d,J=3.2Hz,1H),6.02(d,J=3.2Hz,1H), 2.64(dt,J=15.0,7.5Hz,4H),1.73-1.62(m,2H),1.41-1.27(m,8H),1.23(t,J=7.6Hz,3H),0.88(t,J=6.9Hz,3H).

[0144] 13 C NMR (101MHz, CDCl3) δ156.10,152.34,142.92,128.93,128.08,123.41,106. 69,104.91,31.82,29.21,29.09,28.65,28.20,28.15,22.68,15.57,14.11.

[0145] HRMS-ESI + (m / z):C 19 H 27 O[M+H] + calcd for 271.2056,found 271.2091.

[0146] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 33 , obtain L 33 (Yellow liquid, 69.8 mg, yield: 82.23%).

[0147]

[0148] 1 H NMR (400MHz, CDCl3) δ7.78(d,J=8.3Hz,2H),7.22(d,J=8.5Hz,2H),6.75(d,J=12.0Hz,1H),6.47(d,J=12.0Hz,1H) ,2.64(q,J=7.6Hz,2H),2.52-2.42(m,2H),1.56-1.47(m,4H),1.18(dd,J=9.5,5.8Hz,9H),0.79(t,J=6.9Hz,3H).

[0149] 13 C NMR (101MHz, CDCl3) δ156.10,152.38,142.92,128.90,128.08,123.41,106. 69,104.91,31.82,29.21,29.09,28.65,28.20,28.15,22.68,15.57,14.11.

[0150] HRMS-ESI + (m / z):C 19 H 26 KO2 [M+K] + calcd for 325.1564, found 325.1561.

[0151] Example 12 Compound L 41 Preparation

[0152] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-butylbromobenzene and equimolar amounts of 2-methylfuran to obtain A. 41 (Colorless oily liquid, 0.56 g, yield: 65.33%).

[0153]

[0154] 1H NMR (400MHz, CDCl3) δ7.52(d,J=7.8Hz,2H),7.14(d,J=7.9Hz,2H),6.45(d,J=2.9Hz,1H),6.00(d,J=2.1Hz,1H),2. 58(t,J=7.8Hz,2H),2.33(s,3H),1.58(dt,J=15.3,7.5Hz,2H),1.34(dd,J=14.8,7.4Hz,2H),0.92(t,J=7.3Hz,3H).

[0155] 13 C NMR (101MHz, CDCl3) δ152.62,151.53,141.62,128.81,128.69,126.84,123.34,107.61,105.14,35.46,33.64,22.40,14.02,13.74.

[0156] HRMS-ESI + (m / z):C 15 H 18 KO[M+K] + calcd for 253.0989, found 253.0978.

[0157] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 41 , obtain L 41 (Yellow liquid, 46.0 mg, yield: 66.58%).

[0158]

[0159] 1 H NMR (400MHz, CDCl3) δ7.85(d,J=8.3Hz,2H),7.27(d,J=8.3Hz,2H),6.86(d,J=12.1Hz,1H),6.53(d,J=12.1Hz,1H), 2.73-2.59(m,2H),2.27(s,3H),1.61(dq,J=12.9,7.5Hz,2H),1.35(dq,J=14.6,7.3Hz,2H),0.93(t,J=7.3Hz,3H).

[0160] 13C NMR (101MHz, CDCl3) δ199.69,192.82,149.61,136.48,135.22,133.67,128.86,128.80,35.78,33.16,29.83,22.32,13.89.

[0161] HRMS-ESI + (m / z):C 15 H 18 NaO2[M+Na] + calcd for 253.1199, found 253.1180.

[0162] Example 13 Compound L 42 Preparation

[0163] S1: The experiment was conducted according to the method in S1 of Example 1, using an equimolar amount of 4-n-butylbromobenzene to obtain A. 42 (Colorless oily liquid, 0.61 g, yield: 66.79%).

[0164]

[0165] 1 H NMR (400MHz, CDCl3) δ7.44(d,J=7.9Hz,2H),7.06(d,J=7.9Hz,2H),6.38(d,J=3.0Hz,1H),5.93(d,J=2.2Hz,1H),2.61(q,J=7.5Hz,2 H), 2.50 (t, J = 7.7Hz, 2H), 1.50 (dt, J = 15.4, 7.6Hz, 2H), 1.26 (dd, J = 14.8, 7.4Hz, 2H), 1.17 (t, J = 7.5Hz, 3H), 0.83 (t, J = 7.3Hz, 3H).

[0166] 13 C NMR (101MHz, CDCl3) δ157.25,152.41,141.59,128.83,128.77,128.65,12 6.81,123.34,105.95,104.89,35.42,33.60,22.35,21.53,13.98,12.26.

[0167] HRMS-ESI + (m / z):C 16 H 21 O[M+H] + calcd for 229.1587, found 229.1583.

[0168] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 42 , obtain L 42 (Yellow liquid, 57.9 mg, yield: 78.99%).

[0169]

[0170] 1 H NMR (400MHz, CDCl3) δ7.85(d,J=8.3Hz,2H),7.27(d,J=8.2Hz,2H),6.84(d,J=12.0Hz,1H),6.55(d,J=12.0Hz,1H),2.70-2.63(m,2 H), 2.57 (q, J = 7.2Hz, 2H), 1.61 (dq, J = 12.8, 7.5Hz, 2H), 1.35 (dq, J = 14.6, 7.3Hz, 2H), 1.08 (t, J = 7.2Hz, 3H), 0.92 (t, J = 7.3Hz, 3H).

[0171] 13 C NMR (101MHz, CDCl3) δ202.48,193.00,149.47,136.05,135.21,133.71,128.83,128.77,35.89,35.78,33.17,22.32,13.88,7.50.

[0172] HRMS-ESI + (m / z):C 16 H 21 O2[M+H] + calcd for 245.1536, found 245.1521..

[0173] Example 14 Compound L 43 Preparation

[0174] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-butylfuran and equimolar amounts of 4-n-butylbromobenzene to obtain A. 43 (Colorless oily liquid, 0.61 g, yield: 59.48%).

[0175]

[0176] 1H NMR (400MHz, CDCl3) δ7.52(t,J=8.7Hz,2H),7.16(d,J=8.2Hz,2H),6.47(d,J=3.2Hz,1H),6.03(d,J=3.2Hz, 1H),2.67(t,J=7.6Hz,2H),2.63-2.56(m,2H),1.71-1.55(m,4H),1.46-1.30(m,4H),0.93(q,J=7.4Hz,6H).

[0177] 13 C NMR (101MHz, CDCl3) δ156.03,152.36,141.54,128.85,128.64,123.31,106.70,104.88,35.42,33.61,30.28,27.90,22.35,22.31,13.98,13.87.

[0178] HRMS-ESI + (m / z):C 18 H 25 O[M+H] + calcd for 257.1900,found 257.1904.

[0179] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 43 , obtain L 43 (Yellow liquid, 71.5 mg, yield: 87.5%).

[0180]

[0181] 1 H NMR (400MHz, CDCl3) δ7.76(d,J=8.3Hz,2H),7.18(d,J=8.1Hz,2H),6.74(d,J=12.0Hz,1H),6.46(d,J=12.0Hz,1H),2.65- 2.52(m,2H),2.46(t,J=7.4Hz,2H),1.51(ddq,J=15.1,13.0,7.5Hz,4H),1.34-1.12(m,4H),0.82(dt,J=20.1,7.3Hz,6H).

[0182] 13C NMR (101MHz, CDCl3) δ201.97,193.15,149.46,135.91,135.48,133.71,128.82,128.77,42.41,35.79,33.19,25.59,22.33,22.20,13.89,13.83.

[0183] HRMS-ESI + (m / z):C 18 H 25 O2[M+H] + calcd for 273.1849, found 273.1850.

[0184] Example 15 Compound L 44 Preparation

[0185] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-pentylfuran and 4-n-butylbromobenzene to obtain A. 44 (Colorless oily liquid, 0.72 g, yield: 66.56%).

[0186]

[0187] 1 H NMR (400MHz, CDCl3) δ7.53(d,J=8.2Hz,2H),7.15(d,J=8.2Hz,2H),6.47(d,J=3.2Hz,1H),6.02(d,J=3.2Hz,1H), 2.66(t,J=7.6Hz,2H),2.62-2.56(m,2H),1.77-1.54(m,4H),1.36(dq,J=10.6,7.4Hz,6H),0.91(q,J=7.1Hz,6H).

[0188] 13 C NMR (101MHz, CDCl3) δ156.07,152.39,141.55,128.89,128.80,128.66,126.84,123. 34,106.73,104.91,35.45,33.64,31.46,28.20,27.87,22.50,22.38,14.07,14.01.

[0189] HRMS-ESI + (m / z):C 19 H 27 O[M+H] +calcd for 271.2056, found 271.2094

[0190] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 44 , obtain L 44 (Yellow liquid, 62.1 mg, yield: 72.27%).

[0191]

[0192] 1 H NMR (400MHz, CDCl3) δ7.76(d,J=8.3Hz,2H),7.18(d,J=8.1Hz,2H),6.73(d,J=12.0Hz,1H),6.46(d,J=12.0Hz,1H),2.63-2.54(m,2H) ,2.45(dd,J=9.4,5.4Hz,2H),1.58-1.46(m,4H),1.32-1.23(m,3H),1.23-1.15(m,3H),0.84(t,J=7.3Hz,3H),0.78(t,J=6.9Hz,3H).

[0193] 13 C NMR (101MHz, CDCl3) δ201.96,193.17,149.43,135.89,135.51,133.71,128.81,128.77,42.66,35.79,33.19,31.23,23.20,22.44,22.33,13.90.

[0194] HRMS-ESI + (m / z):C 19 H 26 NaO2[M+Na] + calcd for 309.1825, found 309.1807.

[0195] Example 16 Compound L 45 Preparation

[0196] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-n-heptylfuran and 4-n-butylbromobenzene to obtain A. 45 (Colorless oily liquid, 0.65 g, yield: 54.44%).

[0197]

[0198] 1H NMR (400MHz, CDCl3) δ7.49-7.43(m,2H),7.08(d,J=8.4Hz,2H),6.40(d,J=3.2Hz,1H),5.95(d,J=3.2Hz, 1H),2.58(t,J=7.6Hz,2H),2.55-2.48(m,2H),1.64-1.47(m,4H),1.34-1.15(m,10H),0.90-0.77(m,6H).

[0199] 13 C NMR (101MHz, CDCl3) δ156.08,152.37,141.55,128.86,128.65,123.33,106.70,104 .90,35.43,33.62,31.83,29.22,29.10,28.22,28.17,22.70,22.36,14.13,13.99.

[0200] HRMS-ESI + (m / z):C 21 H 31 O[M+H] + calcd for 299.2369, found 299.2390.

[0201] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 45 , obtain L 45 (Yellow liquid, 78.5 mg, yield: 83.21%).

[0202]

[0203] 1 H NMR (400MHz, CDCl3) δ7.76(d,J=8.3Hz,2H),7.19(d,J=8.3Hz,2H),6.74(d,J=12.0Hz,1H),6.47(d,J=12.0Hz,1H),2.64- 2.54(m,2H),2.46(t,J=7.4Hz,2H),1.59-1.45(m,4H),1.34-1.14(m,10H),0.85(t,J=7.3Hz,3H),0.78(t,J=6.9Hz,3H).

[0204] 13C NMR (101MHz, CDCl3) δ201.97,193.18,149.44,135.86,135.53,133.70,128.80, 128.76,42.71,35.79,33.19,31.65,29.05,23.52,22.61,22.34,14.08,13.90.

[0205] HRMS-ESI + (m / z):C 21 H 30 NaO2[M+Na] + calcd for 337.2138, found 337.2159.

[0206] Example 17 Compound L 51 Preparation

[0207] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of o-bromotoluene and equimolar amounts of 2-ethylbromobenzene to obtain A. 51 (Colorless oily liquid, 0.42 g, yield: 60.96%).

[0208]

[0209] 1 H NMR (400MHz, CDCl3) δ7.61(d,J=7.6Hz,1H),7.20-6.99(m,3H),6.34(d,J=2.8Hz,1H),6.00(d,J=0.9Hz,1H),2.39(s,3H),2.29(s,3H).

[0210] 13 C NMR (101MHz, CDCl3) δ151.76,151.46,134.07,131.10,130.47,126.90,126.53,125.95,109.59,107.46,22.02,13.71.

[0211] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 51 , obtain L 51 (Yellow liquid, 27.0 mg, yield: 47.81%).

[0212]

[0213] 1H NMR (400MHz, Chloroform-d) δ7.64 (d, J=7.8, 1.4Hz, 1H), 7.41 (t, J=7.5, 1.4Hz, 1H), 7.3 2-7.18(m,2H),6.81(d,J=12.0Hz,1H),6.49(d,J=11.9Hz,1H),2.63(s,3H),2.26(s,3H).

[0214] 13 C NMR (101MHz, CDCl3) δ199.34,195.88,139.81,137.93,135.19,132.27,132.17,130.14,125.54,29.84,21.37.

[0215] HRMS-ESI+(m / z):C 12 H 12 O2NH4[M+NH4]+calcd for 206.1176,found 206.1156.

[0216] Example 18 Compound L 52 Preparation

[0217] S1: The experiment was conducted according to the method in S1 of Example 1, using an equimolar amount of o-bromotoluene to obtain A. 52 (Colorless oily liquid, 0.22 g, yield: 29.53%).

[0218]

[0219] 1 H NMR (400MHz, CDCl3) δ7.73-7.64(m,1H),7.27-7.12(m,3H),6.42(d,J=3.2Hz,1H ),6.11-6.04(m,1H),2.71(q,J=7.5Hz,2H),2.47(s,3H),1.28(t,J=7.6Hz,3H).

[0220] 13 C NMR (101MHz, CDCl3) δ157.12,151.67,134.12,131.08,130.52,126.87,126.57,125.90,109.26,105.80,21.97,21.49,12.24.

[0221] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 52 , obtain L 52(Yellow liquid, 47.4 mg, yield: 78.12%).

[0222]

[0223] 1 H NMR (400MHz, CDCl3) δ7.56(d,J=7.6Hz,1H),7.31(t,J=7.5Hz,1H),7.22-7.12(m,2H),6.69(d,J =12.0Hz,1H),6.43(d,J=12.0Hz,1H),2.55(s,3H),2.46(q,J=7.3Hz,2H),0.98(t,J=7.3Hz,3H).

[0224] 13 C NMR (101MHz, CDCl3) δ202.20,196.04,139.71,137.72,135.72,134.95,132.15,132.11,130.19,125.52,35.93,21.40,7.55.

[0225] HRMS-ESI + (m / z):C 13 H 14 O2[M+Na] + calcd for 225.0886, found 225.0884.

[0226] Example 19 Compound L 53 Preparation

[0227] S1: The experiment was conducted according to the method in S1 of Example 1, using equimolar amounts of 2-,5-dimethylbromobenzene and equimolar amounts of 2-methylfuran to obtain A. 53 (Colorless oily liquid, 0.20 g, yield: 26.85%).

[0228]

[0229] 1 H NMR (400MHz, CDCl3) δ7.51 (s, 1H), 7.10 (d, J = 7.7Hz, 1H), 6.97 (dd, J = 7.7, 1.0Hz, 1H ),6.40(d,J=3.2Hz,1H),6.10-6.04(m,1H),2.43(s,3H),2.37(s,3H),2.35(s,3H).

[0230] 13C NMR (101MHz, CDCl3) δ151.90,151.34,135.36,131.08,131.03,130.23,127.71,127.07,109.47,107.44,21.55,21.06,13.71.

[0231] S2: The experiment was conducted according to the method in S2 of Example 1, using an equimolar amount of A. 53 , obtain L 53 (Yellow liquid, 35.3 mg, yield: 58.18%).

[0232]

[0233] 1 H NMR (400MHz, Chloroform-d) δ7.44 (s, J=1.8Hz, 1H), 7.21 (dd, J=7.8, 1.9Hz, 1H), 7.15 (d, J=7.8 Hz,1H),6.81(d,J=12.0Hz,1H),6.47(d,J=12.0Hz,1H),2.57(s,3H),2.33(s,3H),2.25(s,3H).

[0234] 13 C NMR (101MHz, CDCl3) δ199.66,196.02,138.04,136.76,135.66,135.39,135.20,133.19,132.20,130.85,29.97,29.83,21.02.

[0235] HRMS-ESI+(m / z):C 13 H 14 O2[M] + calcd for 202.0994, found 202.1010.

[0236] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for the electrocatalytic ring-opening of furan to prepare cis-olefins, characterized in that, The ring-opening reaction of compound A was carried out by electrocatalysis to give compound L; in, R1 is selected from alkyl groups; R2 is selected from hydrogen or alkyl; The ring-opening reaction includes an electrolyte, wherein the electrolyte is either potassium hydroxide or potassium carbonate. The ring-opening reaction includes a solvent, wherein the solvent is any one or a combination of ethanol and methanol; The current for the open-loop reaction is 4-40 mA.

2. The method according to claim 1, characterized in that, R1 is selected from C1-C10 alkyl groups.

3. The method according to claim 2, characterized in that, R1 is selected from methyl, ethyl, n-butyl, n-pentyl, or n-heptyl.

4. The method according to claim 1, characterized in that, R2 is selected from hydrogen or C1-C6 alkyl.

5. The method according to claim 4, characterized in that, R2 is selected from hydrogen, methyl, ethyl, or n-butyl.

6. The method according to claim 1, characterized in that, In the reaction system, the concentration of compound A is 0.01-0.1 M.

7. The method according to claim 6, characterized in that, In the reaction system, the concentration of compound A is 0.02 M.

8. The method according to claim 1, characterized in that, In the reaction system, the concentration of the electrolyte is 0.01-0.3 M.

9. The method according to claim 8, characterized in that, In the reaction system, the concentration of the electrolyte is 0.1 M.

10. The method according to claim 1, characterized in that, The current for the open-loop reaction is 6 mA.

11. The method according to claim 1, characterized in that, The working electrode of the electrocatalysis is a Pt electrode; the counter electrode of the electrocatalysis is any one of a Cu electrode, an Ag electrode, a Pt electrode, an Au electrode, and a graphite electrode.

12. The method according to claim 1, characterized in that, The ring-opening reaction is carried out at a temperature of 20-30℃.

13. The method according to claim 12, characterized in that, The ring-opening reaction was performed at room temperature.

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