A method for synthesizing fluorene compounds

Abstract

The application discloses a synthesis method of a fluorene compound, and steps are as follows: 2-iodostyrene compound and 2-bromophenylboronic acid pinacol ester are used as raw materials, a coupling reaction is carried out in a reaction container in the presence of a palladium catalyst, a ligand, a base and an organic solvent, after the reaction is finished, post-treatment is carried out, and the fluorene compound is obtained. The fluorene ring and three carbon-carbon bonds are constructed by one-pot method, and the fluorene skeleton is quickly constructed. The reaction has the advantages of simple operation, easily obtained raw materials, wide substrate applicability and easily separated target product. Since the fluorene compound is an important functional molecular skeleton structure, the fluorene compound has very wide application in the fields of fine chemical industry and pharmacy.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for synthesizing fluorene compounds. Background Technology

[0002] Fluorenes are not only important intermediates in organic synthesis but also a class of important functional organic molecules, widely used in organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and drug synthesis. Therefore, developing efficient and convenient methods for constructing these compounds is of great interest in synthetic chemistry. Currently, the synthesis methods for fluorenes are mainly limited by the use of strong acids, strong bases, and strong oxidizing agents, resulting in a limited substrate range, difficulty in preparation, relatively simple synthetic methods, and poor product diversity. Therefore, developing a simple, mild, and widely applicable synthetic method for fluorenes has significant application value. Summary of the Invention

[0003] To address the problems of harsh reaction conditions, limited substrate range and difficulty in preparation, relatively simple synthesis methods and poor product diversity in existing technologies, the present invention aims to provide a synthesis method for fluorene compounds, which constructs the fluorene ring and three carbon-carbon bonds in a one-pot process, thereby achieving rapid construction of the fluorene skeleton.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for synthesizing fluorene compounds includes the following steps: using 2-iodostyrene compound and pinacol ester of 2-bromophenylboronic acid as raw materials, a coupling reaction is carried out in a reaction vessel in the presence of a palladium catalyst, ligand, base and organic solvent. After the reaction is completed, the fluorene compounds are obtained through post-treatment.

[0006] The reaction formula for the synthesis method is as follows:

[0007]

[0008] In the formula, R 1 Selected from one of the functional groups: hydrogen atom, methyl, chlorine, methoxy, fluorine, or trifluoromethyl; R 2 Selected from one of the functional groups: methyl, ethyl, n-butyl, or trifluoromethyl; R 3 It is selected from one of hydrogen atom, methyl, methoxy, trifluoromethyl, fluorine or chlorine.

[0009] Preferably, the palladium catalyst is one of palladium acetate, palladium chloride, palladium trifluoroacetate, bis(tricyclohexylphosphine)dichloride, or bis(triphenylphosphine)dichloride.

[0010] Preferably, the ligand is one of triphenylphosphine, tris(p-methylphenyl)phosphine, tris(p-methoxyphenyl)phosphine, tris(p-fluorophenyl)phosphine, tricyclohexylphosphine tetrafluoroborate, tri-tert-butylphosphine tetrafluoroborate, 1,2-bis(diphenylphosphine)ethane, bis(diphenylphosphine)methane, 1,4-bis(diphenylphosphine)butane, 1,3-bis(diphenylphosphine)propane, and 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene.

[0011] Preferably, the alkali is one of cesium carbonate, cesium acetate, potassium carbonate, sodium acetate, and potassium phosphate.

[0012] Preferably, the organic solvent is one of acetonitrile, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, and toluene. More preferably, the organic solvent is dioxane.

[0013] Preferably, the coupling reaction is carried out at a temperature of 80-110°C for 12-20 hours. More preferably, the reaction temperature is 90°C for 16 hours.

[0014] Preferably, the molar ratio of the 2-iodostyrene compound, 2-bromophenylboronic acid pinacol ester, palladium catalyst, ligand and base is 0.1:0.3:0.01:0.02:0.3.

[0015] Preferably, the concentration of the 2-iodostyrene compound in the reaction solution is 0.1 mol / L.

[0016] Preferably, the coupling reaction is carried out under the protection of an inert gas.

[0017] Preferably, the post-treatment is as follows: removing the organic solvent by rotary evaporation under reduced pressure, concentrating, mixing the residue with silica gel, and eluting by column chromatography using a mixture of petroleum ether and ethyl acetate in a volume ratio of 100:1 to 20:1 as the eluent.

[0018] Beneficial effects:

[0019] By employing the above-described technology, the beneficial effects of the present invention compared to the prior art are as follows:

[0020] This invention features low reaction cost, safe and readily available raw materials, and advantages such as good functional group tolerance, broad substrate universality, and good reaction selectivity. Specifically:

[0021] 1. The preparation steps of 2-iodostyrene compounds are simple, easy to store, and the reaction steps are concise, enabling the one-step construction of fluorenes.

[0022] 2. The reaction conditions are mild, requiring no strong acids, bases, or oxidants. The catalyst dosage is low, and costs are controllable.

[0023] 3. The reaction exhibits high selectivity, demonstrating excellent chemoselectivity. Since fluorene compounds are an important functional molecular framework, they have wide applications in the fields of medicine, pesticides, and materials. Therefore, this invention has significant application value and socio-economic benefits. Attached Figure Description

[0024] Figure 1 The 1H NMR spectrum of the product structure in Example 1;

[0025] Figure 2 The 1H NMR spectrum of the product structure in Example 2;

[0026] Figure 3 The 1H NMR spectrum of the product structure in Example 3;

[0027] Figure 4 The 1H NMR spectrum of the product structure in Example 4;

[0028] Figure 5 The 1H NMR spectrum of the product structure in Example 5;

[0029] Figure 6 The 1H NMR spectrum of the product structure in Example 6;

[0030] Figure 7 The 1H NMR spectrum of the product structure in Example 7;

[0031] Figure 8 The 1H NMR spectrum of the product structure in Example 8;

[0032] Figure 9 The 1H NMR spectrum of the product structure in Example 9;

[0033] Figure 10 The 1H NMR spectrum of the product structure in Example 10;

[0034] Figure 11 The 1H NMR spectrum of the product structure in Example 11;

[0035] Figure 12 The 1H NMR spectrum of the product structure in Example 12;

[0036] Figure 13 The 1H NMR spectrum of the product structure in Example 13;

[0037] Figure 14 The 1H NMR spectrum of the product structure in Example 14;

[0038] Figure 15 The 1H NMR spectrum of the product structure in Example 15 is shown. Detailed Implementation

[0039] The present invention provides a method for synthesizing fluorene compounds, the specific steps of which are as follows: 2-iodostyrene compound, pinacol ester of 2-bromophenylboronic acid, palladium catalyst, ligand, base, and organic solvent are added sequentially to a reaction vessel. The mixture is heated to 80-110℃ and reacted for 12-20 hours. After the reaction is complete, the mixture is cooled, the solvent is removed, and the fluorene compounds are efficiently obtained by simple separation by column chromatography. The reaction formula is as follows:

[0040]

[0041] In the formula, R 1 Selected from one of the functional groups: hydrogen atom, methyl, chlorine, methoxy, fluorine, or trifluoromethyl; R 2 Selected from one of the functional groups: methyl, ethyl, n-butyl, or trifluoromethyl; R 3 It is selected from one of hydrogen atom, methyl, methoxy, trifluoromethyl, fluorine or chlorine.

[0042] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0043] Example 1:

[0044] The target product structure of this embodiment is as follows:

[0045]

[0046] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (77%).

[0047] 1 H NMR (400 MHz, CDCl3) δ 7.66 (d, J = 7.4 Hz, 2H), 7.44 – 7.22 (m,7H), 6.96 (ddd, J = 10.0, 7.3, 1.9 Hz, 2H), 6.74 (dd, J = 7.4, 2.1 Hz, 1H), 3.32 (s, 2H), 1.59 (s, 3H).

[0048] Example 2:

[0049] The target product structure of this embodiment is as follows:

[0050]

[0051] To a 25 mL reaction flask, 1-iodo-4-methyl-2-(1-propen-2-yl)benzene (51.6 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (72%).

[0052] 1 H NMR (400 MHz, CDCl3) δ 7.62 (d, J = 7.5 Hz, 1H), 7.55 (d, J = 7.6Hz, 1H), 7.41 (dd, J = 7.6, 1.7 Hz, 1H), 7.30 (td, J = 7.1, 1.9 Hz, 1H), 7.27– 7.19 (m, 2H), 7.16 – 7.08 (m, 2H), 6.97 (ddd, J = 9.3, 7.3, 1.9 Hz, 2H), 6.73 (dd, J = 7.3, 2.1 Hz, 1H), 3.31 (d, J = 3.0 Hz, 2H), 2.39 (s, 3H), 1.58(s, 3H).

[0053] Example 3:

[0054] The target product structure of this embodiment is as follows:

[0055]

[0056] To a 25 mL reaction flask, 1-iodo-4-fluoro-2-(1-propen-2-yl)benzene (52.4 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (65%).

[0057] 1 H NMR (400 MHz, CDCl3)δ 7.67 – 7.54 (m, 2H), 7.42 (dd, J = 7.7, 1.7Hz, 1H), 7.38 – 7.19 (m, 3H), 7.07 – 6.91 (m, 4H), 6.76 (dd, J = 7.3, 2.1 Hz,1H), 3.41 – 3.22 (m, 2H), 1.58 (s, 3H).

[0058] Example 4:

[0059] The target product structure of this embodiment is as follows:

[0060]

[0061] To a 25 mL reaction flask, 1-iodo-5-chloro-2-(1-propen-2-yl)benzene (55.6 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (69%).

[0062] 1H NMR (400 MHz, CDCl3)δ 7.69 – 7.58 (m, 2H), 7.41 (dd, J = 7.6, 1.8Hz, 1H), 7.32 (ddtt, J = 7.6, 6.4, 3.9, 1.8 Hz, 3H), 7.23 – 7.12 (m, 2H), 6.99 (ddd, J = 9.2, 7.3, 1.9 Hz, 2H), 6.73 (dd, J = 7.3, 2.1 Hz, 1H), 3.44 –3.25 (m, 2H), 1.58 (s, 3H).

[0063] Example 5:

[0064] The target product structure of this embodiment is as follows:

[0065]

[0066] To a 25 mL reaction flask, 1-iodo-5-methyl-2-(1-propen-2-yl)benzene (51.6 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (74%).

[0067] 1 H NMR (400 MHz, CDCl3) δ 7.64 (d, J = 7.4 Hz, 1H), 7.48 (s, 1H), 7.41 (dd, J = 7.7, 1.7 Hz, 1H), 7.34 – 7.21 (m, 3H), 7.17 (d, J = 7.7 Hz, 1H), 7.07 (dd, J = 7.7, 1.6 Hz, 1H), 7.02 – 6.90 (m, 2H), 6.76 (dd, J = 7.4, 2.0Hz, 1H), 3.31 (s, 2H), 2.41 (s, 3H), 1.56 (s, 3H).

[0068] Example 6:

[0069] The target product structure of this embodiment is as follows:

[0070]

[0071] 1-(but-1-en-2-yl)-2-iodo-4-methoxybenzene (57.6 mg, 0.2 mmol), pinacol ester of 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially to a 25 mL reaction flask. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–20:1, v / v) to obtain the target product (79%).

[0072] 1 H NMR (400 MHz, CDCl3) δ 7.60 (dt, J = 7.2, 1.1 Hz, 1H), 7.44 – 7.23(m, 4H), 7.19 – 7.09 (m, 2H), 6.91 (ddd, J = 6.7, 3.9, 2.1 Hz, 2H), 6.81 (dd,J = 8.3, 2.4 Hz, 1H), 6.65 (dd,J = 7.1, 2.4 Hz, 1H), 3.86 (s, 3H), 3.36 (d,J = 4.1 Hz, 2H), 2.20 (qd,J = 7.0, 2.9 Hz, 2H), 0.27 (t, J = 7.3 Hz, 3H).

[0073] Example 7:

[0074] The target product structure of this embodiment is as follows:

[0075]

[0076] To a 25 mL reaction flask, 1-iodo-2-(3,3,3-trifluoroprop-1-en-2-yl)benzene (59.6 mg, 0.2 mmol), pinacol 2-bromophenylboronic acid (169.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (63%).

[0077] 1 H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 7.6 Hz, 2H), 7.59 (d, J = 7.5Hz, 2H), 7.38 (td, J = 7.5, 1.2 Hz, 2H), 7.34 – 7.23 (m, 3H), 6.80 (td, J =7.6, 1.8 Hz, 1H), 6.72 (td, J = 7.5, 1.4 Hz, 1H), 6.32 (dd, J = 7.7, 1.8 Hz, 1H), 3.89 (s, 2H).

[0078] Example 8:

[0079] The target product structure of this embodiment is as follows:

[0080]

[0081] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-4-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (190.2 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and stirred in an oil bath at 90 °C for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (55%).

[0082] 1 H NMR (400 MHz, CDCl3) δ 7.64 – 7.48 (m, 2H), 7.39 (d, J = 2.2 Hz, 1H), 7.37 – 7.23 (m, 5H), 6.92 (dd, J = 8.3, 2.2 Hz, 1H), 6.54 (d, J = 8.3Hz, 1H), 3.30 (d, J = 3.7 Hz, 2H), 1.57 (s, 3H).

[0083] Example 9:

[0084] The target product structure of this embodiment is as follows:

[0085]

[0086] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-5-methylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (178.2 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (71%).

[0087] 1 H NMR (400 MHz, CDCl3)δ 7.63 (d, J = 7.4 Hz, 1H), 7.47 (d, J = 1.5Hz, 1H), 7.33 – 7.22 (m, 4H), 7.15 (d, J = 7.7 Hz, 1H), 7.06 (dd, J = 7.8,1.6 Hz, 1H), 6.76 (dd, J = 8.1, 2.2 Hz, 1H), 6.57 (d, J = 2.2 Hz, 1H), 3.22(s, 2H), 2.41 (s, 3H), 2.09 (s, 3H), 1.55 (s, 3H).

[0088] Example 10:

[0089] The target product structure of this embodiment is as follows:

[0090]

[0091] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-5-methoxyphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (187.8 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (67%).

[0092] 1 H NMR (400 MHz, CDCl3) δ 7.65 – 7.55 (m, 1H), 7.40 (dd, J = 7.3, 1.4Hz, 1H), 7.34 – 7.19 (m, 4H), 7.17 (d, J = 2.4 Hz, 1H), 6.82 (dd, J = 1.58 (s, 3H).

[0093] Example 11:

[0094] The target product structure of this embodiment is as follows:

[0095]

[0096] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (180.6 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and stirred in an oil bath at 90 °C for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (61%).

[0097] 1 H NMR (400 MHz, CDCl3) δ 7.64 – 7.53 (m, 2H), 7.36 – 7.23 (m, 3H), 7.13 (dd, J = 8.4, 2.6 Hz, 1H), 7.01 (dd, J = 9.0, 6.4 Hz, 2H), 6.74 – 6.57(m, 2H), 3.38 – 3.20 (m, 2H), 1.57 (s, 3H).

[0098] Example 12:

[0099] The target product structure of this embodiment is as follows:

[0100]

[0101] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-5-trifluoromethylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (210.6 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the mixture was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (57%).

[0102] 1H NMR (400 MHz, CDCl3) δ 7.77 (d, J = 1.5 Hz, 1H), 7.59 (dt, J = 6.9,1.5 Hz, 1H), 7.45 (dd, J = 8.0, 1.7 Hz, 1H), 7.38 (d, J = 8.2 Hz, 2H), 7.34 –7.24 (m, 3H), 7.07 (dd, J = 8.4, 2.3 Hz, 1H), 6.69 (d, J = 2.2 Hz, 1H), 3.35 (d, J = 2.9 Hz, 2H), 1.57 (s, 3H).

[0103] Example 13:

[0104] The target product structure of this embodiment is as follows:

[0105]

[0106] To a 25 mL reaction flask, 1-iodo-2-(1-propen-2-yl)benzene (48.8 mg, 0.2 mmol), 2-(2-bromo-5-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (190.2 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (58%).

[0107] 1 H NMR (400 MHz, CDCl3) δ 7.60 – 7.49 (m, 2H), 7.30 – 7.20 (m, 4H), 7.17 – 7.07 (m, 2H), 6.85 (dd, J = 8.5, 2.6 Hz, 1H), 6.55 (d, J = 2.6 Hz,1H), 3.39 – 3.10 (m, 2H), 1.50 (s, 3H).

[0108] Example 14:

[0109] The target product structure of this embodiment is as follows:

[0110]

[0111] To a 25 mL reaction flask, 1-iodo-4-fluoro-2-(1-propen-2-yl)benzene (52.4 mg, 0.2 mmol), 2-(2-bromo-4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (180.6 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (57%).

[0112] 1 H NMR (400 MHz, CDCl3) δ 7.44 (dd, J = 8.0, 5.0 Hz, 2H), 7.07 (dt, J= 8.6, 2.1 Hz, 1H), 6.94 (t, J = 9.1 Hz, 4H), 6.70 – 6.52 (m, 2H), 3.21 (s,2H), 1.53 – 1.46 (m, 3H).

[0113] Example 15:

[0114] The target product structure of this embodiment is as follows:

[0115]

[0116] To a 25 mL reaction flask, 1-iodo-5-methyl-2-(1-propen-2-yl)benzene (51.6 mg, 0.2 mmol), 2-(2-bromo-5-methylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborhecyclopentane (178.2 mg, 0.6 mmol), bis(triphenylphosphine)palladium dichloride (14 mg, 0.02 mmol), tris(p-fluorophenyl)phosphine (13 mg, 0.04 mmol), and cesium carbonate (195.6 mg, 0.6 mmol) were added sequentially. Then, 2.0 mL of acetonitrile was added, the flask was purged with nitrogen, sealed, and placed in an oil bath at 90 °C with stirring for 16 hours. After the reaction was complete, the solvent was removed by rotary evaporation, followed by column chromatography (petroleum ether / ethyl acetate = 100:1–50:1, v / v) to obtain the target product (71%).

[0117] 1H NMR (400 MHz, CDCl3) δ 7.60 – 7.49 (m, 2H), 7.30 – 7.20 (m, 4H), 7.17 – 7.07 (m, 2H), 6.85 (dd, J = 8.5, 2.6 Hz, 1H), 6.55 (d, J = 2.6 Hz,1H), 3.39 – 3.10 (m, 2H), 1.50 (s, 3H).

[0118] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing fluorene compounds, characterized in that, The steps are as follows: using 2-iodostyrene compound and 2-bromophenylboronic acid pinacol ester as raw materials, a coupling reaction is carried out in a reaction vessel in the presence of palladium catalyst, ligand, base and organic solvent. After the reaction is completed, the fluorene compound is obtained through post-treatment. The reaction formula for the synthesis method is as follows: In the formula, R 1 Selected from one of the functional groups: hydrogen atom, methyl, chlorine, methoxy, fluorine, or trifluoromethyl; R 2 Selected from one of the functional groups: methyl, ethyl, n-butyl, or trifluoromethyl; R 3 It is selected from one of hydrogen atom, methyl, methoxy, trifluoromethyl, fluorine or chlorine.

2. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The palladium catalyst is one of palladium acetate, palladium chloride, palladium trifluoroacetate, bis(tricyclohexylphosphine)dichloride, or bis(triphenylphosphine)dichloride.

3. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The ligand is one of triphenylphosphine, tris(p-methylphenyl)phosphine, tris(p-methoxyphenyl)phosphine, tris(p-fluorophenyl)phosphine, tricyclohexylphosphine tetrafluoroborate, tri-tert-butylphosphine tetrafluoroborate, 1,2-bis(diphenylphosphine)ethane, bis(diphenylphosphine)methane, 1,4-bis(diphenylphosphine)butane, 1,3-bis(diphenylphosphine)propane, and 4,5-bisdiphenylphosphine-9,9-dimethyloxanthracene.

4. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The alkali is one of cesium carbonate, cesium acetate, potassium carbonate, sodium acetate, and potassium phosphate.

5. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The organic solvent is one of acetonitrile, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, and toluene.

6. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The coupling reaction is carried out at a temperature of 80-110℃ for 12-20 hours.

7. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The molar ratio of the 2-iodostyrene compound, pinacol ester of 2-bromophenylboronic acid, palladium catalyst, ligand and base is 0.1:0.3:0.01:0.02:0.

3.

8. The method for synthesizing fluorene compounds according to claim 1 or 7, characterized in that, The concentration of the 2-iodostyrene compound in the reaction solution is 0.1 mol / L.

9. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The coupling reaction is carried out under inert gas protection.

10. The method for synthesizing fluorene compounds according to claim 1, characterized in that, The post-treatment is as follows: the organic solvent is removed by rotary evaporation under reduced pressure, the mixture is concentrated, the residue is mixed with silica gel, and column chromatography is performed using a mixture of petroleum ether and ethyl acetate in a volume ratio of 100:1 to 20:1 as the eluent.

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