Method for preparing indene and benzofuran through copper-catalyzed propargyl ether rearrangement reaction

Abstract

The invention discloses a method for preparing indene by copper-catalyzed propargyl ether rearrangement reaction, which is characterized by comprising the following step: in the presence of a copper catalyst, a ligand and di-tert-butyl peroxide, in an organic solvent, heating a compound in a formula (1) and a compound in a formula (2) to react to generate an indene compound in a formula (3) or a formula (4). The invention discloses a method for preparing benzofuran by copper-catalyzed propargyl ether rearrangement reaction, which is characterized by comprising the following steps: in the presence of a copper catalyst and alkali, in an organic solvent, heating a compound in a formula (5) to react to generate a benzofuran compound in a formula (6). The preparation method provided by the invention has the advantages of cheap and easily available reaction raw materials, simple reaction operation, wide application range of reaction substrates, easy amplification of reaction, mild reaction conditions and the like, and can realize industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for preparing indene and benzofuran by copper-catalyzed propargyl ether rearrangement reaction. Background Technology

[0002] In organic synthesis, indene and benzofurans are crucial synthetic compounds, yielding a wide variety of compounds with diverse structures through various chemical reactions. They are also widely found as skeletal structures in drug molecules and natural products. For example, the antibiotic pauciflorol F, the antipruritic drug dimetindene, the anti-inflammatory drug sulindac, and the natural product indenestrol A all contain indene structures. Similarly, the antiarrhythmic drug amiodarone, the anti-inflammatory drug pterolinus B, and the anticancer drug fruquintinib all contain benzofuran structures.

[0003] The 1,4-aryl migration rearrangement of propargyl ethers is a highly efficient and simple method for obtaining indene compounds. In 2019, Xia's research group reported a synthetic method for indene compounds based on the 1,4-aryl migration strategy and Friedel-Crafts cyclization reaction (W. He, J. Yu, D. Wang, G. Ran, X.-F. Xia, Org. Chem. Front. 2019, 6, 3575). This method discloses a process using polyfluoroiodides as radical precursors, FeBr2 and Cu(OTf)2 as catalysts, and zinc powder as a reducing agent. The 1,4-aryl migration rearrangement of propargyl ethers yields allyl alcohol, which then undergoes a Friedel-Crafts cyclization reaction in the presence of the strong acid trifluoromethanesulfonic acid to obtain indene compounds. The reaction process is shown in the following equation:

[0004]

[0005] However, this technology has obvious drawbacks: First, the reaction can only use polyfluoroiodides as free radical precursors, thus only indene compounds containing polyfluoroiodides can be obtained; second, the reaction needs to be carried out in two steps, which is not economical; third, the Friedel-Crafts cyclization reaction in the second step uses trifluoromethanesulfonic acid, which is a strong acid, resulting in poor functional group tolerance; and fourth, the reaction cannot yield benzofuran products. Summary of the Invention

[0006] This invention provides a method for preparing indene and benzofuran compounds. This invention is the first to use readily available propargyl ether and boric acid as reaction substrates, and copper catalysis to achieve the synthesis of various indene and benzofuran compounds.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing indene via a copper-catalyzed propargyl ether rearrangement reaction, characterized in that it comprises: in the presence of a copper catalyst, a ligand, and di-tert-butyl peroxide, in an organic solvent, heating a compound of formula (1) and a compound of formula (2) to generate an indene compound of formula (3) or formula (4):

[0009]

[0010] Preferably, the compound of formula (1) is selected from:

[0011]

[0012]

[0013] Preferably, the compound of formula (2) is selected from:

[0014]

[0015] Preferably, the copper catalyst is selected from:

[0016] Copper hexafluorophosphate, copper trifluoromethanesulfonate, copper tetrafluoroborate.

[0017] Preferably, the ligand is selected from:

[0018]

[0019] Preferably, the reaction is carried out in an organic solvent, wherein the organic solvent is at least one selected from 1,2-dichloroethane, dichloromethane, acetonitrile, and tetrahydrofuran.

[0020] Preferably, the molar ratio of the compound of formula (1), the compound of formula (2), and the copper catalyst is 1:1.5-2.5:0.05-0.15.

[0021] The reaction is carried out under heating conditions; the preferred reaction temperature is 40–60°C.

[0022] A method for preparing benzofuran via a copper-catalyzed rearrangement reaction of propargyl ether, characterized in that it comprises: under the conditions of a copper catalyst and a base, in an organic solvent, heating a compound of formula (5) to generate a benzofuran compound of formula (6):

[0023]

[0024] Preferably, the compound of formula (5) is selected from:

[0025]

[0026]

[0027] Preferably, the copper catalyst is selected from:

[0028] Copper hexafluorophosphate, copper trifluoromethanesulfonate, copper tetrafluoroborate.

[0029] Preferably, the alkali is selected from:

[0030] Sodium tert-butoxide, potassium tert-butoxide, sodium carbonate, potassium carbonate, cesium carbonate.

[0031] Preferably, the reaction is carried out in an organic solvent, wherein the organic solvent is at least one selected from 2-methyltetrahydrofuran, tetrahydrofuran, 1,2-dichloroethane, and ethyl acetate.

[0032] Preferably, the molar ratio of the compound of formula (5), the base, and the copper catalyst is 1:1.5-2.5:0.05-0.15.

[0033] The reaction is carried out under heating conditions; the preferred reaction temperature is 70–80°C.

[0034] The indene and benzofuran compounds prepared by this invention are a very important class of organic synthesis intermediates, which can be converted into a variety of organic compounds through various chemical reactions.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) This invention is the first to use readily available propargyl ether and boric acid as reaction substrates and copper catalysis to achieve the synthesis of various indene and benzofuran compounds.

[0037] (2) The preparation method provided by the present invention can be applied to propargyl ethers and boric acids with a variety of different functional groups, and has the advantages of simple and readily available substrates and wide applicability.

[0038] (3) The preparation method of the present invention has the advantages of cheap and readily available reaction raw materials, simple reaction operation, wide range of applicable reaction substrates, easy scale-up of reaction, and mild reaction conditions, and can realize industrial production and application. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0040] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise specified, the mol% of copper catalyst used in each example is based on propargyl ether.

[0041] In the following embodiments, the ligand is:

[0042]

[0043] Example 1: Optimization of conditions for the preparation of indene from the copper-catalyzed propargyl ether rearrangement reaction

[0044]

[0045] In a glove box, Cu(CH3CN)4PF6 (10 mol%), L1 (10 mol%), propargyl ether 1 (0.1 mmol), and phenylboronic acid 2 (0.2 mmol) were weighed into a 4 mL sample vial. DCE (1.0 mL) and DTBP (0.2 mmol) were added sequentially, and the PTFE cap was tightened. The sample vial was removed from the glove box and reacted at 40 °C for 12 hours. After the reaction, the solvent was removed by rotary evaporation to obtain the crude product. The conversion and yield of the reaction were analyzed by thin-layer chromatography or nuclear magnetic resonance (NMR). The experimental results showed that the NMR yield was 97%. Replacing Cu(CH3CN)4OTf and Cu(CH3CN)4BF4 with Cu(CH3CN)4PF6, while keeping other conditions unchanged, yielded NMR yields of 67% and 43%, respectively. Replacing L1 with L2, L3, L4, L5, and L6, while keeping other conditions unchanged, yielded NMR yields of 28%, 31%, 25%, 53%, and 20%, respectively. Replacing DCE with MeCN, DCM, and THF respectively, while keeping other conditions unchanged, yielded NMR yields of 45%, 92%, and 35%, respectively. Changing the reaction temperature to 60 degrees Celsius, while keeping other conditions constant, yielded an NMR yield of 89%.

[0046] Example 2: Investigation of the reaction substrate of propargyl ether and boric acid

[0047]

[0048] In a glove box, Cu(CH3CN)4PF6 (10 mol%), L1 (10 mol%), propargyl ether (0.2 mmol), and boric acid (0.4 mmol) were weighed into a 4 mL sample vial. DCE (2.0 mL) and DTBP (0.4 mmol) solvents were added sequentially, and the PTFE cap was tightened. The sample vial was removed from the glove box and reacted at 40 °C for 12 hours. After the reaction was complete, the solvent was removed by rotary evaporation to obtain the crude product. The conversion and yield of the reaction were analyzed by thin-layer chromatography or nuclear magnetic resonance. The experimental results are shown in Table 1.

[0049] Table 1. Investigation of reaction substrates for propargyl ether and boric acid

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] The analytical data for compounds 3a-3t and 4a-4i are as follows:

[0056] Analysis data of indene 3a

[0057] 1 H NMR (600MHz, CDCl3, sample at 25°C) 7.53 (d, J=7.1Hz, 1H), 7.44-7.39 (m, 2H), 7.36 (dd, J=7.3, 2.7Hz, 3H), 7.30-7.14 (m, 8H), 3.92 (s, 2H)

[0058] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ147.0, 142.4, 141.1, 140.0, 136.6, 136.1, 129.4, 128.8, 128.3, 128.2, 127.4, 126.9, 126.5, 125.1, 123.6, 120.4, 41.2.

[0059] Analysis data of indene 3b

[0060] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.02 (d, J=8.3Hz, 2H), 7.56 (d, J=7.0Hz, 1H), 7.48 (t, J=9.0Hz, 2H), 7.31-7.18 (m, 8H), 3.95 (s, 2H), 2.65 (s, 3H)

[0061] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ197.8, 146.2, 142.6, 142.4141.4, 138.8, 136.2, 136.1, 129.7, 1 28.9, 128.37, 128.35, 127.3, 126.7, 125.3, 123.8, 120.2, 41.5, 26.6.

[0062] Analysis data of Indene 3C

[0063] 1H NMR (600MHz, CDCl3, sample at 25°C) δ8.12-8.07 (m, 2H), 7.55 (d, J=6.9Hz, 1H), 7.46-7.43 (m, 2H), 7.31-7.16 (m, 8H), 3.95 (s, 3H), 3.94 (s, 2H).

[0064] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ167.1, 146.2, 142.4, 142.4, 141.2, 138.9, 136.1, 130.1, 129.5, 129.1, 128.4, 128.3, 127.3 126.6, 125.3, 123.8, 120.2, 52.2, 41.4.

[0065] Analysis data of Indene 3D

[0066] 1 H NMR (600MHz, DMSO-d6, sample at 25°C) δ7.46 (t, J=7.5Hz, 2H), 7.40 (t, J=7.2Hz, 1H), 7.28 (d, J=7.5Hz, 2H), 7.21 (m, 4H), 7.15 (m, 2H), 6.53 (s, 1H), 6.00 (s, 2H), 3.89 (s, 2H).

[0067] 13 C NMR (151MHz, DMSO-d6, sample at 25℃) δ146.9, 146.3, 140.6, 139.3, 136.7, 136.6, 136.0, 129.5, 129.4, 128.7, 128.2, 128.1, 127.2, 105.7, 101.4, 101.0.41.0, 40.6.

[0068] Analysis data of indene 3e

[0069] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.70 (d, J=8.1Hz, 2H), 7.58 (d, J=7.0Hz, 1H), 7.51 (d, J=8.0Hz, 2H), 7.33-7.20 (m, 8H), 3.97 (s, 2H). 13C NMR (151MHz, CDCl3, sample at 25℃) δ145.1, 141.6, 141.3, 139.0, 137.4, 135.0, 128.8, 128.5 (q, J=33.2Hz), 127.4, 127 .3, 126.3, 125.6, 124.7 (q, J=3.3Hz), 124.3, 123.3 (q, J=272.2Hz), 122.7, 119.1, 40.5.

[0070] 19 F NMR(565MHz, CDCl3, sample at 25℃)δ-62.41

[0071] Analysis data of indene 3f

[0072] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.38-7.33(m, 2H), 7.31-7.28(m, 2H), 7.21-7.16(m, 2H), 7.13(t, J=7.5Hz , 2H), 7.10-7.04 (m, 3H), 6.76 (dd, J=8.3, 1.9Hz, 1H), 3.82 (s, 2H), 3.79 (s, 3H).

[0073] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ158.3, 144.2, 140.2, 139.6, 138.8, 136.8, 136.3, 129.3, 128.8, 128.1, 128.1, 127.3, 126.6, 120.8, 112.1, 110.1, 55.7, 41.1.

[0074] Analysis data of indene 3g

[0075] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.53 (d, J=7.9Hz, 1H), 7.34 (t, J=7.7Hz, 1H), 7.30 (t, J=7.4Hz, 1H), 7.25-7.18 (m, 5H), 7.17-7.13 (m, 2H), 6.86 (d, J=8.3Hz, 1H), 6.81 (dd, J=8.3, 1.9Hz, 1H), 3.99 (d, J=22.2Hz, 1H), 3.91 (d, J=22.2Hz, 1H), 3.85 (s, 3H).

[0076] 13C NMR (151MHz, CDCl3, sample at 25℃) δ158.4, 143.7, 140.1, 139.7, 137.2, 136.4, 135.8, 133.9, 131.4, 130.0, 129.0, 128.3, 127.3, 120.9, 112.2, 110.1, 55.6, 40.7.

[0077] Analysis data of indene 3h

[0078] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.37 (s, 1H), 7.34-7.31 (m, 2H), 7.22 (dd, J=16.7, 8.2Hz, 5H), 7.19-7.14 (m, 1H) , 7.12 (s, 1H), 7.08 (d, J = 8.3Hz, 1H), 6.83 (d, J = 8.1Hz, 1H), 3.87 (s, 2H), 3.85 (s, 3H).

[0079] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ158.4, 144.1, 139.8, 139.7, 138.3, 138.1, 136.3, 134.6, 130.1, 129.3 , 128.3, 128.2, 128.1, 127.7, 127.6, 126.9, 120.6, 112.3, 110.3, 55.7, 41.2.

[0080] Analysis data of Indene 3i

[0081] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.39 (d, J=8.2Hz, 2H), 7.30 (d, J=8.2Hz, 2H), 7.27-7.20 (m, 4H), 7.20-7.16 (m, 1H), 7 .14 ​​(s, 1H), 7.09 (d, J=8.3Hz, 1H), 6.84 (dd, J=8.3, 1.8Hz, 1H), 3.88 (s, 2H), 3.86 (s, 3H)..

[0082] 13C NMR (151MHz, CDCl3, sample at 25℃) δ158.4, 144.2, 139.7, 139.6, 138.2, 136.5, 134.7, 133.2, 130.8, 129.1, 128.3, 128.1, 126.8, 120.6, 112.2, 110.3, 55.7, 41.2.

[0083] Analysis data of Indene 3j

[0084] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.09 (d, J=8.1Hz, 2H), 7.44 (d, J=8.1Hz, 2H), 7.24-7.16 (m, 5H), 7.14 (s, 1H), 7.0 9 (d, J=8.4Hz, 1H), 6.84 (dd, J=8.3, 2.0Hz, 1H), 3.95 (s, 3H), 3.90 (s, 2H), 3.86 (s, 3H).

[0085] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ167.1, 158.4, 144.2, 141.4, 140.1, 138.5, 136.1, 130.1, 129.5, 129.1, 128.3, 128.1, 126.7, 120.6, 112.2, 110.3, 55.7, 52.1, 41.3.

[0086] Analysis data of Indene 3k

[0087] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.44-7.38(m, 2H), 7.38-7.34(m, 3H), 7.24(m, 2H), 7.19(m, 2H), 7.14(m, 1H), 7.12(m, 1H), 7.11( d, J=8.4Hz, 1H), 6.82 (dd, J=8.3, 2.3Hz, 1H), 4.08 (q, J=7.0Hz, 2H), 3.88 (s, 2H), 1.44 (t, J=7.0Hz, 3H).

[0088] 13C NMR (151MHz, CDCl3, sample at 25℃) δ157.6, 144.2, 140.1, 139.6, 138.8, 136.8, 136.3, 129.3, 128.8, 128.2, 128.1, 127.3, 126.6, 120.8, 112.8, 110.7, 63.85, 41.1, 15.0.

[0089] Analysis data of Indene 3l

[0090] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.32 (m, 2H), 7.21 (dt, J=15.1, 7.4Hz, 4H), 7.15 (m, J=6.9Hz, 1H), 7.13-7.05 (m, 4H ), 6.83 (dd, J=8.3, 2.2Hz, 1H), 4.08 (q, J=7.0Hz, 2H), 3.87 (s, 2H), 1.44 (t, J=7.0Hz, 3H).

[0091] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ162.2 (d, J=246.3Hz), 157.7, 144.1, 139.9, 139.2, 138.5, 136.6, 132.1 (d, J=3.0Hz), 131. 0 (d, J=7.7Hz), 128.2, 128.1, 126.7, 120.6, 115.8 (d, J=21.7Hz), 112.9, 110.9, 63.9, 41.1, 14.9.

[0092] 19 F NMR (565MHz, CDCl3, sample at 25℃) δ-114.73.

[0093] Analysis data of Indene 3m

[0094] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.39 (d, J=8.3Hz, 2H), 7.31 (d, J=8.3Hz, 2H), 7.27-7.20 (m, 4H), 7.17 (dd, J=9.2, 4.2Hz, 1H), 7.13 (s, 1H) , 7.09 (d, J=8.3Hz, 1H), 6.84 (dd, J=8.3, 2.0Hz, 1H), 4.09 (q, J=7.0Hz, 2H), 3.87 (s, 2H), 1.45 (t, J=7.0Hz, 3H).

[0095] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ157.7, 144.1, 139.6, 139.5, 138.3, 136.5, 134.9, 133.2, 130.8, 129.1, 128.3, 128.1, 126.8, 120.6, 112.9, 110.9, 63.9, 41.2, 15.0.

[0096] Analysis data of indene 3n

[0097] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.53 (d, J=8.3Hz, 2H), 7.25-7.19 (m, 6H), 7.18-7.14 (m, 1H), 7.10 (t, J=5.5Hz, 1H), 7.06 (d, J=8.4Hz, 1H), 4.07 (q, J=7.0Hz, 2H), 3.85 (s, 2H), 1.43 (t, J=7.0Hz, 3H).

[0098] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ157.7, 144.1, 139.5, 139.5, 138.3, 136.5, 135.3, 132.0, 131.1, 128.3, 128.1, 126.8, 121.3, 120.6, 112.9, 110.9, 63.9, 41.3, 15.0.

[0099] Analysis data of indene 3o

[0100] 1 H NMR (600MHz, CDCl3, I sample at 25℃) δ7.72 (d, J=8.2Hz, 2H), 7.25-7.19 (m, 4H), 7.16 (dd, J=8.9, 4.4Hz, 1H), 7.09 (d, J=8.1Hz, 3H), 7.06 (d, J=8.4Hz, 1H), 6.81 (dd, J=8.4, 2.1Hz, 1H), 4.06 (q, J=7.0Hz, 2H), 3.84 (s, 2H), 1.43 (t, J=7.0Hz, 3H).

[0101] 13C NMR (151MHz, CDCl3, sample at 25℃) δ157.7, 144.2, 139.5, 138.3, 138.0, 136.5, 135.9, 131.3, 128.3, 128.1, 126.8, 120.6, 112.9, 110.9, 92.9, 63.9, 41.3, 15.0.

[0102] Analysis data of indene 3p

[0103] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.68 (d, J=8.0Hz, 2H), 7.49 (d, J=8.0Hz, 2H), 7.25-7.17 (m, 5H), 7.14 (d, J=1.3Hz, 1H), 7.08 (d, J=8.4Hz, 1H), 6.85 (dd, J=8.4, 2.2Hz, 1H), 4.10 (q, J=7.0Hz, 2H), 3.91 (s, 2H), 1.46 (t, J=7.0Hz, 3H).J

[0104] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ157.8, 144.2, 140.2, 139.3, 138.1, 136.3, 129.8, 129.4 (q, J=32.3Hz), 128.3, 128.1 , 127.0, 125.7 (q, J=3.1Hz,), 124.3 (q, J=272.2Hz), 120.5, 113.0, 110.9, 63.9, 41.4, 14.9

[0105] 19 F NMR (565MHz, CDCl3, sample at 25℃) δ-62.38.

[0106] Analysis data of indene 3q

[0107] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.01 (t, J=6.9Hz, 2H), 7.47 (d, J=8.2Hz, 2H), 7.23-7.20 (m, 5H), 7.13 (d, J=1.5Hz, 1H), 7.09 (d, J=8.4 Hz, 1H), 6.83 (dd, J=8.4, 2.2Hz, 1H), 4.09 (q, J=7.0Hz, 2H), 3.90 (s, 2H), 2.65 (s, 2H), 1.44 (t, J=7.0Hz, 3H).

[0108] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ197.8, 157.8, 144.2, 141.6, 140.2, 139.3, 138.5, 136.4, 136.1, 129. 7, 128.9, 128.3, 128.2, 126.9, 120.6, 113.0, 111.0, 63.9, 41.4, 26.6, 14.9.

[0109] Analysis data of Indene 3r

[0110] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.09 (t, J=9.5Hz, 2H), 7.44 (d, J=8.2Hz, 2H), 7.23-7.14 (m, 5H), 7.13 (d, J=1.6Hz, 1H), 7.08 (d, J=8.4 Hz, 1H), 6.83 (dd, J=8.4, 2.2Hz, 1H), 4.09 (q, J=7.0Hz, 2H), 3.95 (s, 3H), 3.89 (s, 2H), 1.44 (t, J=7.0Hz, 3H).

[0111] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ167.1, 157.8, 144.2, 141.4, 140.1, 139.4, 138.6, 136.4, 130.1, 129. 5, 129.1, 128.3, 128.1, 126.9, 120.6, 112.9, 110.9, 63.9, 52.1, 41.3, 14.9.

[0112] Analysis data of indene 3s

[0113] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.27 (d, J=8.7Hz, 2H), 7.53 (d, J=8.7Hz, 2H), 7.25-7.16 (m, 5H), 7.15 (s, 1H), 7.08 (d, J=8 .4Hz, 1H), 6.85 (dd, J=8.4, 2.1Hz, 1H), 4.10 (q, J=7.0Hz, 2H), 3.91 (s, 2H), 1.45 (t, J=7.0Hz, 3H)

[0114] 13C NMR (151MHz, CDCl3, sample at 25℃) δ158.0, 147.1, 144.2, 143.6, 141.5, 138.7, 137.4, 136.0, 130.4, 128.5, 128.2, 127.3, 124.1, 120.4, 113.1, 111.1, 63.9, 41.6, 14.9.

[0115] Analysis data of indene 3t

[0116] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.97 (d, J=8.2Hz, 2H), 7.56 (d, J=8.2Hz, 2H), 7.24-7.15 (m, 5H), 7.13 (d, J=1.3Hz, 1H), 7.06 (d, J=8.4 Hz, 1H), 6.83 (dd, J=8.4, 2.1Hz, 1H), 4.08 (q, J=7.0Hz, 2H), 3.90 (s, 2H), 3.12 (s, 3H), 1.44 (t, J=7.0Hz, 3H).

[0117] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ157.9, 144.2, 142.5, 141.1, 139.3, 138.9, 137.5, 136.0, 130.4, 1 28.5, 128.2, 127.9, 127.2, 120.4, 113.1, 111.0, 63.9, 44.5, 41.6, 14.9.

[0118] Analysis data of indene 4a

[0119] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.50 (t, J=9.4Hz, 1H), 7.41 (t, J=7.4Hz, 2H), 7.35 (d, J=7.5Hz, 3H), 7.27-7.23 (m, 1H), 7.21 ( t, J=8.1Hz, 2H), 7.17 (d, J=7.8Hz, 1H), 7.01 (d, J=7.7Hz, 2H), 3.89 (s, 2H), 2.30 (d, J=15.5Hz, 3H).

[0120] 13C NMR (151MHz, CDCl3, sample at 25℃) δ147.1, 142.4, 141.2, 139.3, 136.8, 136.3, 133.7, 129.5, 129.0, 128.8, 128.2, 127.4, 126.5, 124.9, 123.6, 120.3, 41.2, 21.2.

[0121] Analysis data of indene 4b

[0122] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.53 (d, J=7.2Hz, 1H), 7.43 (t, J=7.3Hz, 2H), 7.40-7.33 (m, 3H), 7.30-7.20 (m, 5H), 6.92-6.87 (m, 2H), 3.89 (s, 2H).

[0123] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ161.8 (d, J=247.3Hz), 146.8, 142.2, 139.9 (d, J=15.4Hz), 135.9, 132.7 (d, J=3.1Hz), 129.9, 129.8, 129.3, 128.9, 127.5, 126.6, 125.1, 123.6, 120.4, 115.1 (d, J=21.1Hz), 41.3.

[0124] 19 F NMR (565MHz, CDCl3, sample at 25℃): δ-114.91.

[0125] Analysis data of indene 4c

[0126] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.53 (d, J=7.1Hz, 1H), 7.43 (t, J=7.3Hz, 2H), 7.40-7.36 (m, 1H), 7.35-7.32 (m, 2H), 7.30-7.14 (m, 8H), 3.88 (s, 1H).

[0127] 13C NMR (151MHz, CDCl3, sample at 25℃) δ146.7, 142.3, 140.6, 139.7, 135.7, 135.1, 132.7, 129.5, 129.3, 128.9, 128.4, 127.6, 126.6, 125.3, 123.6, 120.5, 41.1

[0128] Analysis data of Indene 4D

[0129] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.55 (d, J=7.1Hz, 1H), 7.45 (t, J=7.3Hz, 2H), 7.40 (dd, J=12.8, 5.4Hz, 1 H), 7.36 (d, J=7.0Hz, 2H), 7.32-7.23 (m, 4H), 7.18-7.08 (m, 3H), 3.91 (s, 2H).

[0130] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ146.6, 142.3, 141.3, 139.4, 138.5, 135.6, 134.1, 129.3, 129.2, 129.0, 128.2, 127.7, 126.9, 126.7, 126.4, 125.5, 123.7, 120.7, 41.1.

[0131] Analysis data of indene 4e

[0132] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.53 (d, J=6.9Hz, 1H), 7.43 (t, J=7.3Hz, 2H), 7.37 (t, J=7.4Hz, 1H), 7.33 ( dd, J=10.8, 7.9Hz, 4H), 7.29-7.20 (m, 3H), 7.13 (d, J=8.5Hz, 2kkH), 3.88 (s, 2H).

[0133] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ146.7, 142.2, 140.7, 139.7, 135.7, 135.5, 131.3, 129.8, 129.3, 129.0, 127.6, 126.6, 125.3, 123.6, 121.0, 120.6, 41.0.

[0134] Analysis data of indene 4f

[0135] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.50 (d, J=7.2Hz, 1H), 7.42 (t, J=7.5Hz, 2H), 7.35 (dd, J=10.2, 4.3H z, 3H), 7.28-7.13 (m, 5H), 6.74 (d, J=8.8Hz, 2H), 3.88 (s, 2H), 3.76 (s, 3H).

[0136] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ158.6, 147.2, 142.2, 140.8, 138.5, 136.4, 129.5, 129.4, 129.2, 128.8, 127.3, 126.5, 124.7, 123.5, 120.1, 113.7, 55.2, 41.2.

[0137] Analysis data of indene 4g

[0138] I1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.55 (d, J=6.8Hz, 1H), 7.44 (t, J=6.4Hz, 4H), 7.40 (d, J=6.9Hz, 1H), 7.3 7-7.32 (m, 4H), 7.29 (dd, J=13.6, 6.7Hz, 2H), 7.25-7.23 (m, 1H), 3.93 (s, 2H).

[0139] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ146.5, 142.4, 142.1, 140.1, 139.3, 135.5, 129.2, 129.0, 128.6. (q, J=32.5Hz), 12 8.4, 127.8, 126.7, 125.7, 125.1 (q, J=3.5Hz), 124.2 (q, J=271.9Hz), 123.7, 120.9, 41.1.

[0140] 19 F NMR (565MHz, CDCl3, sample at 25℃): δ-62.55.

[0141] Analysis data of indene 4h

[0142] 1H NMR (600MHz, CDCl3, sample at 25°C) δ7.84 (s, 1H), 7.78-7.70 (m, 2H), 7.60 (dd, J=16.5, 7.8Hz, 2H), 7.48-7.37 (m, 7H), 7.35-7.26 (m, 4H), 4.07 (s, 2H).

[0143] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ147.0, 142.5, 141.1, 140.5, 136.1, 134.2, 133.5, 132.4, 129.5, 128.9, 128.1, 127.6, 127.5, 127.4, 127.1, 126.6, 126.6, 126.1, 125.9, 125.2, 123.6, 120.5, 41.4.

[0144] Analysis data of indene 4i

[0145] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.43-7.37 (m, 3H), 7.35-7.30 (m, 3H), 7.21-7.12 (m, 2H), 7.01 (d, J=7.3Hz, 1H), 5.93 (dd , J=4.4, 3.5Hz, 1H), 3.66 (s, 2H), 2.10 (dd, J=6.0, 3.2Hz, 2H), 1.90 (s, 2H), 1.56-1.47 (m, 4H).

[0146] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ147.7, 144.0, 141.7, 137.8, 137.4, 134.5, 129.4, 128.2, 127.6, 127.0, 126.3, 124.5, 123.3, 119.9, 40.6, 28.6, 26.1, 23.1, 22.1.

[0147] Example 3: Optimization of conditions for the preparation of benzofuran from copper-catalyzed propargyl ether rearrangement reaction

[0148]

[0149]

[0150] In a glove box, Cu(CH3CN)4PF6 (10 mol%), propargyl ether 1 (0.2 mmol), and sodium tert-butoxide (0.4 mmol) were weighed into a 4 mL sample vial, and 2-MeTHF solvent (2.0 mL) was added. The PTFE cap was then tightened. The sample vial was removed from the glove box and reacted at 70 °C for 12 hours. After the reaction, the solvent was removed by rotary evaporation to obtain the crude product. The conversion and yield of the reaction were analyzed by thin-layer chromatography or nuclear magnetic resonance (NMR). The experimental results showed that the NMR yield was 43%. When Cu(CH3CN)4OTf and Cu(CH3CN)4BF4 were used instead of Cu(CH3CN)4PF6, with other conditions remaining unchanged, the NMR yields were 27% and 41%, respectively. When potassium tert-butoxide, sodium carbonate, potassium carbonate, and cesium carbonate were used instead of sodium tert-butoxide, with other conditions remaining unchanged, the NMR yields were 28%, 31%, 25%, and 33%, respectively. Replacing 2-MeTHF with EA, DCE, and THF respectively, while keeping other conditions unchanged, yielded NMR yields of 30%, 25%, and 40%, respectively. Changing the reaction temperature to 80 degrees Celsius, while keeping other conditions constant, yielded an NMR yield of 38%.

[0151] Example 4: Investigation of substrates for the reaction of propargyl ether

[0152]

[0153] In a glove box, Cu(CH3CN)4PF6 (10 mol%), propargyl ether (0.2 mmol), and sodium tert-butoxide (0.4 mmol) were weighed into a 4 mL sample vial, and 2-MeTHF solvent (2.0 mL) was added. The PTFE cap was then tightened. The sample vial was removed from the glove box and reacted at 70 °C for 12 hours. After the reaction was complete, the solvent was removed by rotary evaporation to obtain the crude product. The conversion and yield of the reaction were analyzed by thin-layer chromatography or nuclear magnetic resonance. The experimental results are shown in Table 2.

[0154] Table 2. Investigation of reaction substrates for propargyl ether.

[0155]

[0156]

[0157]

[0158]

[0159] The analytical data for compounds 5a-5t are as follows:

[0160] Analytical data of benzofuran 5a

[0161] 1H NMR (600MHz, CDCl3, sample at 25°C) δ7.58 (d, J=7.3Hz, 1H), 7.52-7.45 (m, 5H), 7.37 (t, J=7.1Hz, 1H), 7.27-7.21 (m, 4H), 2.55 (s, 3H).

[0162] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ154.1, 151.29, 132.9, 129.0, 128.8, 128.7, 127.0, 123.5, 122.6, 119.3, 116.9, 110.8, 12.8.

[0163] Analytical data of benzofuran 5b

[0164] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.53-7.44 (m, 5H), 7.39 (m, 1H), 7.27 (s, 1H), 7.16 (t, J=7.8Hz, 1H), 2.59 (s, 3H).

[0165] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ152.4, 149.8, 132.3, 130.5, 128.9, 128.8, 127.3, 123.8, 123.5, 117.9, 117.7, 116.3, 12.8.

[0166] Analytical data of benzofuran 5c

[0167] 1 H NMR (600MHz, CDCl3) δ7.53 (d, J=1.9Hz, 1H), 7.52-7.45 (m, 4H), 7.40-7.36 (m, 2H), 7.22 (dd, J=8.6, 1.9Hz, 1H), 2.54 (s, 3H).

[0168] 13 C NMR (151MHz, CDCl3) δ152.9, 152.4, 132.1, 130.3, 128.9, 128.9, 128.4, 127.3, 123.7, 119.1, 116.8, 111.7, 12.9.

[0169] Analytical data of benzofuran 5d

[0170] 1H NMR (600MHz, CDCl3, sample at 25°C) δ7.69 (d, J=1.6Hz, 1H), 7.53-7.45 (m, 4H), 7.41-7.30 (m, 3H), 2.54 (s, 3H).

[0171] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ152.8, 152.7, 132.1, 130.9, 128.9, 128.9, 127.3, 126.4, 122.1, 116.7, 115.8, 112.2, 12.8.

[0172] Analytical data of benzofuran 5e

[0173] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.79 (s, 1H), 7.63 (d, J=7.6Hz, 2H), 7.59-7.50 (m, 6H), 7.45 (t, J=7.6Hz, 2H), 7.41 (t, J=7.3Hz, 1H), 7.35 (t, J=7.3Hz, 1H), 2.59 (s, 3H).

[0174] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ153.7, 152.1, 141.9, 136.5, 132.8, 129.4, 129.0, 128.9, 128.7, 127.5, 127.1, 126.8, 123.3, 118.0, 117.2, 110.9, 12.9.

[0175] Analytical data of benzofuran 5f

[0176] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.59 (s, 1H), 7.54-7.49 (m, 4H), 7.43-7.36 (m, 3H), 6.81 (dd, J=17.5 , 10.9Hz, 1H), 5.71 (d, J=17.5Hz, 1H), 5.20 (d, J=10.9Hz, 1H), 2.54 (s, 3H).

[0177] 13C NMR (151MHz, CDCl3, sample at 25℃) δ 153.9, 151.9, 137.2, 132.8, 132.7, 129.1, 129.0, 128.8, 127.1, 122.0, 117.2, 117.1, 112.4, 110.7, 12.8. Analytical data for 5g of benzofuran.

[0178] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.51 (m, 4H), 7.39 (m, 1H), 7.36 (d, J=8.9Hz, 1H), 7.06 (d, J=1.9Hz, 1H), 6.89 (dd, J=8.8, 2.3Hz, 1H), 3.84 (s, 3H), 2.53 (s, 3H).

[0179] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ156.1, 152.3, 149.0, 133.0, 129.4, 128.9, 128.8, 127.0, 117.2, 111.9, 111.2, 102.4, 56.0, 12.9.

[0180] Analytical data of benzofuran over 5 hours

[0181] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.49 (d, J=7.6Hz, 1H), 7.46-7.40 (m, 3H), 7.26-7.18 (m, 2H), 7.15 (t, J=8.6Hz, 2H), 2.49 (s, 3H). 13 C NMR (151MHz, CDCl3, sample 25℃) δ161.9 (d, J=246.3Hz), 154.0, 151.3, 130.5 (d, J=7.8Hz), 128.8 (d, J=3 .2Hz), 128.7, 123.7, 122.7, 119.1, 116.5, 115.7 (d, J=21.6Hz), 110.8, 12.7.

[0182] Analytical data of benzofuran 5i

[0183] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.53 (d, J=7.6Hz, 1H), 7.45 (m, 5H), 7.31-7.22 (m, 2H), 2.53 (s, 3H).

[0184] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ154.0, 151.5, 132.9, 131.3, 130.2, 129.0, 128.5, 123.7, 122.8, 119.1, 116.0, 110.9, 12.8.

[0185] Analytical data of benzofuran 5j

[0186] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.75 (d, J=8.1Hz, 2H), 7.69 (d, J=7.7Hz, 2H), 7.66 (d, J=7.7Hz, 1H), 7.62 (d, J= 8.2Hz, 2H), 7.53-7.48 (m, 3H), 7.40 (t, J=7.4Hz, 1H), 7.33-7.25 (m, 2H), 2.61 (s, 3H).

[0187] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ154.1, 151.4, 140.8, 139.8, 131.9, 129.3, 128.8, 128.7, 127.5, 127.3, 127.1, 123.6, 122.7, 119.4, 116.6, 110.8, 12.9.

[0188] Analytical data of benzofuran 5k

[0189] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.63 (d, J=7.6Hz, 1H), 7.53 (d, J=8.3Hz, 2H), 7.50-7.45 (m, 3H), 7.25 (dt, J=20.6, 7.0Hz, 2H), 2.57 (s, 3H), 1.41 (s, 9H).

[0190] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ154.1, 151.1, 149.8, 129.9, 128.9, 128.5, 125.6, 123.4, 122.5, 119.5, 116.7, 110.7, 34.6, 31.4, 12.9.

[0191] Analytical data of benzofuran 5l

[0192] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.55 (d, J=7.4Hz, 1H), 7.44 (d, J=8.0Hz, 1H), 7.41 (d, J=8.6Hz, 2H), 7.23 (m, 2 H), 7.01 (d, J=8.6Hz, 2H), 4.10 (q, J=7.0Hz, 2H), 2.52 (s, 3H), 1.46 (t, J=7.0Hz, 3H).

[0193] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ158.1, 154.0, 150.8, 130.0, 129.1, 125.0, 123.4, 122.5, 119.3, 116.5, 114.8, 110.763.5, 14.9, 12.8.

[0194] Analytical data of benzofuran 5m

[0195] 1 H NMR (600MHz, CDCl3, sample at 25°C) δ7.57 (d, J=7.4Hz, 1H), 7.47-7.39 (m, 5H), 7.29-7.21 (m, 2H), 2.56 (s, 3H), 2.54 (s, 3H).

[0196] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ154.1, 151.3, 137.2, 129.7, 129.3, 128.7, 127.1, 123.6, 122.7, 119.3, 116.4, 110.8, 16.0, 12.8.

[0197] Analytical data of benzofuran 5n

[0198] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.61 (d, J=7.5Hz, 1H), 7.47 (d, J=8.1Hz, 1H), 7.42 (t, J=7.9Hz, 1H), 7.31-7.22 (m, 2H) , 7.11 (d, J=7.5Hz, 1H), 7.08 (s, 1H), 6.93 (dd, J=8.3, 2.3Hz, 1H), 3.88 (s, 3H), 2.57 (s, 3H).

[0199] 13C NMR (151 MHz, CDCl3, sample at 25 ℃) δ 159.9, 154.0, 151.4, 134.2, 129.7, 128.7, 123.6, 122.6, 121.4, 119.4, 116.8, 114.7, 112.4, 110.8, 55.3, 12.9. Analytical data for benzofuran 5O.

[0200] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.57 (d, J=7.4Hz, 1H), 7.46 (d, J=8.0Hz, 1H), 7.28-7.22 (m, 2H), 7.05-7.0 (m, 3H), 3.96 (s, 3H), 3.94 (s, 3H), 2.55 (s, 3H).

[0201] 13 C NMR (151 MHz, CDCl3, sample at 25 ℃) δ 154.0, 150.9, 149.2, 148.2, 129.0, 125.5, 123.5, 122.6, 121.4, 119.2, 116.7, 112.4, 111.7, 110.7, 56.0, 12.8. Analytical data for benzofuran 5p.

[0202] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.59 (d, J=7.4Hz, 1H), 7.45 (d, J=8.0Hz, 1H), 7.29-7.20 (m, 2H), 7.04 (s, 1H), 7.00 (s, 2H), 4.32 (s, 4H), 2.54 (s, 3H).

[0203] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ153.9, 151.0, 143.7, 142.7, 128.9, 126.1, 123.4, 122.5, 122.1, 119.3, 117.7, 117.6, 116.3, 110.7, 77.2, 77.0, 76.8, 64.4, 12.8.

[0204] Analytical data of benzofuran 5q

[0205] 1H NMR (600MHz, CDCl3, sample at 25°C) δ7.53 (d, J=7.7Hz, 1H), 7.43 (d, J=7.8Hz, 1H), 7.27-7.18 (m, 2H), 6.94m, 3H), 6.01 (s, 2H), 2.50 (s, 3H).

[0206] 13 C NMR (151 MHz, CDCl3, sample at 25 ℃) δ 154.0, 151.0, 148.0, 146.7, 128.9, 126.6, 123.6, 122.6, 122.4, 119.3, 116.7, 110.8, 109.4, 108.7, 101.1, 12.8. Analytical data for benzofuran 5r.

[0207] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.75-7.72 (m, 1H), 7.46-7.41 (m, 1H), 7.30-7.23 (m, 2H), 7.01 (d, J=3.4Hz, 1H), 6.82 (d, J=3.0Hz, 1H), 2.62 (s, 3H), 2.56 (s, 3H).

[0208] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ153.9151.6, 139.1, 131.8, 128.4, 125.6, 125.3, 123.7, 122.7, 119.7, 111.2, 110.7, 15.2, 13.3.

[0209] Analytical data of benzofuran 5s

[0210] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ7.64 (d, J=8.2Hz, 1H), 7.62-7.52 (m, 3H), 7.40 (t, J=7.7Hz, 1H), 7.32 (dd, J=17.9, 7.7Hz , 2H), 7.24 (dd, J=15.4, 7.1Hz, 2H), 7.17 (t, J=7.4Hz, 1H), 7.10 (t, J=7.5Hz, 1H), 2.43 (s, 3H).

[0211] 13C NMR (151MHz, CDCl3, sample at 25℃) δ156.6, 156.4, 154.2, 152.2, 129.0, 127.3, 127.1, 127.0, 125.0, 123.8, 123.8, 123.4, 122.7, 122.7, 122.6, 120.0, 115.3, 111.37, 110.9, 110.8, 12.9.

[0212] Analytical data of 5t of benzofuran

[0213] 1 H NMR (600MHz, CDCl3, sample at 25℃) δ8.06 (s, 1H), 8.00 (d, J=7.6Hz, 1H), 7.69 (d, J=8.4Hz, 1H), 7.61 (ddd, J=10.0, 8.3, 3.3Hz, 3H), 7.50 (dd, J= 11.0, 4.3Hz, 2H), 7.38 (t, J=7.4Hz, 1H), 7.31 (dd, J=11.2, 4.1Hz, 1H), 7.27 (dd, J=9.8, 4.0Hz, 1H), 2.60 (s, 3H).

[0214] 13 C NMR (151MHz, CDCl3, sample at 25℃) δ156.7, 155.4, 154.1, 151.3, 129.2, 128.3, 127.5, 127.4, 124.8, 124.1, 123.7, 122.8, 122.7, 121.0, 120.8, 119.2, 117.0, 112.0, 111.8, 110.8, 12.8.

[0215] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing indene via a copper-catalyzed propargyl ether rearrangement reaction, characterized in that, include: In the presence of a copper catalyst, ligand, and di-tert-butyl peroxide, in an organic solvent, the compound of formula (1) reacts with the compound of formula (2) upon heating to produce an indene compound of formula (3) or (4): The compound of formula (1) is selected from: The compound in formula (2) is selected from:

2. The method according to claim 1, characterized in that, The copper catalyst is selected from: Copper hexafluorophosphate, copper trifluoromethanesulfonate, copper tetrafluoroborate.

3. The method according to claim 1, characterized in that, The ligands are selected from:

4. The method according to claim 1, characterized in that, The organic solvents mentioned are selected from: 1,2-Dichloroethane, dichloromethane, acetonitrile, tetrahydrofuran.

5. The method according to claim 1, characterized in that, The heating temperature is 40℃ or 60℃.

6. A method for preparing benzofuran via a copper-catalyzed rearrangement reaction of propargyl ether, characterized in that, include: Under the conditions of copper catalyst and base, in an organic solvent, the compound of formula (5) reacts upon heating to produce the benzofuran compound of formula (6): The compound of formula (5) is selected from:

7. The method according to claim 6, characterized in that, The copper catalyst is selected from: Copper hexafluorophosphate, copper trifluoromethanesulfonate, copper tetrafluoroborate.

8. The method according to claim 6, characterized in that, The alkali is selected from: Sodium tert-butoxide, potassium tert-butoxide, sodium carbonate, potassium carbonate, cesium carbonate.

9. The method according to claim 6, characterized in that, The organic solvents mentioned are selected from: 2-Methyltetrahydrofuran, tetrahydrofuran, 1,2-dichloroethane, ethyl acetate.

10. The method according to claim 6, characterized in that, The heating temperature is 70℃ or 80℃.

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