A bisphosphine compound containing imidazole skeleton and its preparation method and application

Abstract

The application belongs to the technical field of organic synthesis and metal catalytic ligand, and particularly relates to a kind of double phosphine compound containing imidazole skeleton and its preparation method and application, under the action of palladium catalyst, 1H-imidazole-5-boronic acid pinacol ester and 2-bromine iodine benzene are obtained 1,4-bis (2-bromine phenyl) -1H-imidazole intermediate by C-C coupling and C-N coupling series reaction;Again under the protection of inert gas, 1,4-bis (2-bromine phenyl) -1H-imidazole intermediate is dissolved in anhydrous solvent and reacts with organic lithium reagent, and then reacts with phosphonium chloride, and the target product is obtained after treatment, the double phosphine compound and palladium catalysis can exhibit excellent catalytic activity and selectivity in carbon-carbon coupling reaction.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and metal catalytic ligand technology, and particularly relates to a bisphosphonate compound containing an imidazole skeleton, its preparation method and application. Background Technology

[0002] Organophosphine ligands are a core component of transition metal catalysis. By adjusting the electronic effects and steric hindrance of phosphine ligands, the activity and selectivity of chemical reactions can be significantly altered. Bisphosphine ligands, such as 1,1'-bis(diphenylphosphine)ferrocene (DPPF) and 2,2'-bis(diphenylphosphine)-1,1'-binaphthyl (BINAP), have been widely used in industrial catalytic processes such as Suzuki coupling, Heck reaction, hydroformylation, and asymmetric hydrogenation.

[0003] The imidazole ring, a five-membered aromatic heterocycle containing two nitrogen atoms, possesses excellent coordination ability, thermal stability, and structural modifiability. Introducing the imidazole skeleton into bisphosphine ligand structures holds promise for obtaining ligand systems with novel electronic properties and spatial configurations. Currently, there are few reports on ligands based on the imidazole-bisphosphine structure, mainly because reaction competition exists at the N-1 / C-2 sites of the imidazole ring, making selectivity difficult to control and resulting in low yields of the target product. Therefore, the development of such ligands has significant academic and applied value. Summary of the Invention

[0004] The purpose of this invention is to provide a bisphosphonate compound containing an imidazole skeleton, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A bisphosphonate compound containing an imidazole skeleton has the following general structural formula: Wherein, R is phenyl, cyclohexyl, isopropyl, tert-butyl, or adamantyl.

[0006] Furthermore, its synthetic route is as follows: .

[0007] Secondly, the present invention provides a method for preparing the bisphosphine compound containing an imidazole skeleton, comprising the following steps: Step (1): Under the action of palladium catalyst, 1H-imidazol-5-boronic acid pinacol ester first undergoes C–C coupling reaction with 2-bromoiodobenzene, and then the generated imidazolium intermediate further undergoes C–N coupling reaction with the remaining 2-bromoiodobenzene to obtain 1,4-bis(2-bromophenyl)-1H-imidazolium intermediate.

[0008] Step (2): Under inert gas protection, the 1,4-bis(2-bromophenyl)-1H-imidazolium intermediate obtained in step (1) is dissolved in an anhydrous solvent, reacted with an organolithium reagent to perform lithium-bromine exchange, and then reacted with phosphine chloride. After post-treatment, the target product is obtained.

[0009] In step (1), the palladium catalyst is selected from any one of Pd(dppf)Cl2, Pd(PPh3)4, Pd2(dba)3, Pd(OAc)2, Pd(PPh3)2Cl2, and Pd(dba)2; the amount of the catalyst is 0.5-15 mol% of 1H-imidazol-5-boronic acid pinacol ester, preferably 1-10 mol%, more preferably 5-10 mol%.

[0010] In step (1), the alkali is selected from one of the following: potassium phosphate, potassium carbonate, cesium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, sodium tert-butoxide, potassium tert-butoxide, sodium phosphate, sodium acetate, triethylamine; the amount of alkali used is 1-5 equivalents of 1H-imidazol-5-boronic acid pinacol ester, preferably 1.5-3 equivalents.

[0011] In step (1), the solvent is a mixture of organic solvent and water, with a volume ratio of organic solvent to water of 10:1 to 2:1, preferably 6:1 to 3:1, and more preferably 4:1; the organic solvent is one of 1,4-dioxane, toluene, xylene, ethylene glycol dimethyl ether, N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran; the reaction temperature is 60-120℃, preferably 80-100℃, and more preferably 90℃; the reaction time is 6-24 hours, preferably 12 hours; and the molar ratio of 1H-imidazolium-5-boronic acid pinacol ester to 2-bromoiodobenzene is 1:2.0-3.5, preferably 1:2.5.

[0012] In step (2), the organolithium reagent is n-butyllithium; the anhydrous solvent is selected from tetrahydrofuran, diethyl ether, methyl tert-butyl ether, and 1,4-dioxane; the reaction temperature is -78℃ to 0℃; the molar ratio of 1,4-bis(2-bromophenyl)-1H-imidazole, organolithium reagent and phosphine chloride is 1:(2.2-2.8):(2.2-2.8), preferably 1:2.4:2.4.

[0013] Thirdly, the present invention provides the application of the bisphosphonate compound containing the imidazole skeleton in transition metal catalytic reactions. The compound can be used as a metal ligand to construct metal catalytic systems, and is particularly suitable for palladium-catalyzed carbon-carbon coupling reactions, including the Suzuki coupling reaction, the Heck reaction, and the Buchwald–Hartwig coupling reaction.

[0014] The advantages of this invention are: 1. This invention provides a novel class of bisphosphonic compounds containing an imidazole skeleton, enriching the variety of organophosphonic ligands; 2. The synthetic route of the bisphosphonate compound containing the imidazole skeleton provided by this invention is short, the raw materials are readily available, the operation is simple, it adopts the Suzuki / Buchwald tandem reaction, and it has a wide range of adaptability to palladium catalysts, bases and solvents, making it suitable for large-scale preparation. 3. Bisphosphonates containing an imidazole skeleton can have their electronic effects and steric hindrance of phosphine ligands easily tuned by changing the R group (Ph, Cy, iPr, tBu, Ad), providing a flexible choice for optimizing catalytic reaction conditions; 4. This bisphosphine compound exhibits excellent catalytic activity and selectivity in carbon-carbon coupling reactions with palladium catalysis. Detailed Implementation

[0015] Example 1 Preparation method of 1,4-bis(2-bromophenyl)-1H-imidazole: Under nitrogen protection, 1H-imidazol-5-borate pinacol ester (10 mmol, 1.94 g), 2-bromoiodobenzene (25 mmol, 7.07 g), Pd(dppf)Cl2 (1 mmol, 0.73 g), and potassium phosphate (20 mmol, 4.25 g) were added to a 250 mL reaction flask, along with a 1,4-dioxane / water mixture (80 mL / 20 mL). The mixture was heated to 90 °C with stirring and reacted for 12 h. After the reaction was complete, the mixture was cooled to room temperature, diluted with 50 mL of water, and extracted with ethyl acetate (3 × 50 mL). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 10:1 to 4:1) to give a white solid product, 1,4-bis(2-bromophenyl)-1H-imidazolium (2.95 g, yield 78%). 1 H NMR (400 MHz, CDCl3)δ7.87(s, 1H), 7.99 (d, J = 1.6 Hz, 1H), 7.68 (dd, J = 8.3, 1.3 Hz, 1H), 7.60 (dd,J = 7.8,1.4 Hz, 1H), 7.53 (s, 1H), 7.50–7.36 (m, 3H), 7.34–7.28 (m, 1H), 7.23 (ddd, J = 7.9, 7.0,1.8 Hz, 1H). 13C NMR (101MHz, CDCl3)δ144.9, 141.8, 138.0,134.0, 132.8, 131.7, 131.4, 129.0, 129.0, 128.3, 127.1, 121.9, 121.9, 118.0,111.3. HRMS (ESI) m / z: [M+H] + Calculated for [C 15 H 11 Br2N2] + 376.9283; Found 376.9285. Example 2 Preparation method of 1,4-bis(2-(diphenylphosphino)phenyl)-1H-imidazole: Under nitrogen protection, 1,4-bis(2-bromophenyl)-1H-imidazole (5 mmol, 1.89 g) prepared in Example 1 was dissolved in anhydrous tetrahydrofuran (50 mL) and cooled to -78°C. Butyllithium (2.5 M, 12 mmol) was slowly added dropwise, maintaining the internal temperature below -78°C during the addition. After the addition was complete, the reaction was stirred at -78°C for 1 h. Subsequently, diphenylphosphine chloride (12 mmol, 2.65 g) was slowly added dropwise, and the temperature was naturally raised to 0°C after the addition was complete, with continued stirring for 12 h. After the reaction was complete, a saturated ammonium chloride solution (30 mL) was added to quench the reaction, and the mixture was extracted with ethyl acetate (3 × 40 mL). The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 8:1 to 2:1) to give a white solid product 1,4-bis(2-(diphenylphosphino)phenyl)-1H-imidazolium (2.56 g, yield 87%). 1 H NMR (400 MHz, CDCl3)δ7.85 (s,1H), 7.81 (d, J = 1.6 Hz, 1H), 7.66–7.59 (m, 2H), 7.51 (s, 1H), 7.50–7.41 (m,2H), 7.42–7.21(m, 15H), 7.10 (m, 8H). 13 C NMR (101 MHz, CDCl3)δ146.1, 143.8,141.6, 139.5, 137.6, 136.4, 135.8, 134.8, 134.1, 133.7, 131.2, 129.4, 129.3,128.9, 128.7, 128.7, 128.2, 126.4, 126.3,120.7, 117.1. HRMS (ESI) m / z: [M+H]+ Calculated for [C 39 H 31 N2P2] + 589.1957; Found 589.1955. Example 3 Preparation of 1,4-bis(2-(dicyclohexylphosphino)phenyl)-1H-imidazole: Following the procedure of Example 2, diphenylphosphine chloride was replaced with an equimolar amount of dicyclohexylphosphine chloride (12 mmol, 2.79 g). Other conditions were the same as in Example 2. A white solid 1,4-bis(2-(dicyclohexylphosphino)phenyl)-1H-imidazole (2.45 g, yield 80%) was obtained. 1 H NMR(400 MHz, CDCl3)δ7.88 (s, 1H), 7.81 (d, J = 1.8 Hz, 1H), 7.62–7.53 (m, 1H),7.50 (s, 1H), 7.44–7.31 (m, 5H), 7.22 (ddd, J = 7.9, 6.0, 2.0 Hz, 1H), 2.45–2.30 (m,4H), 2.05–1.69 (m, 8H), 1.62–1.28 (m, 32H). 13 C NMR (101 MHz, CDCl3)δ144.7, 142.9, 141.8, 141.6, 138.2, 136.5, 131.0, 129.2, 128.9, 128.2, 124.9,124.9, 119.6, 117.2, 34.9, 34.8, 31.5, 31.4, 27.2, 26.6.HRMS (ESI) m / z: [M+H] + Calculated for [C 39 H 55 N2P2] + 613.3835; Found 613.3838. Example 4 Preparation of 1,4-bis(2-(diisopropylphosphino)phenyl)-1H-imidazole: Following the procedure of Example 2, diphenylphosphine chloride was replaced with an equimolar amount of diisopropylphosphine chloride (12 mmol, 1.83 g). Other conditions were the same as in Example 2. A white solid 1,4-bis(2-(diisopropylphosphino)phenyl)-1H-imidazole (1.65 g, yield 73%) was obtained. 1H NMR(400 MHz, CDCl3)δ7.88 (s, 1H), 7.81 (d, J = 1.7 Hz, 1H), 7.51 (s, 1H), 7.50–7.31(m, 6H), 7.22 (ddd, J = 7.9, 6.1, 2.1 Hz, 1H), 1.90 (dh, J = 8.1, 7.4 Hz, 4H), 0.98–0.92 (m, 24H). 13 C NMR (101 MHz, CDCl3)δ144.9, 141.8, 140.6, 136.6,135.4, 134.9, 134.5, 131.3, 129.2, 128.2, 128.2, 124.9, 124.9,119.5, 117.2,34.0, 33.8, 19.2, 19.2. HRMS (ESI) m / z: [M+H] + Calculated for [C 27 H 39 N2P2] + 453.2583; Found 453.2580. Example 5 Preparation of 1,4-bis(2-(di-tert-butylphosphino)phenyl)-1H-imidazole: Following the procedure of Example 2, diphenylphosphine chloride was replaced with an equimolar amount of di-tert-butylphosphine chloride (12 mmol, 2.17 g). Other conditions were the same as in Example 2. A white solid 1,4-bis(2-(di-tert-butylphosphino)phenyl)-1H-imidazole (1.93 g, yield 76%) was obtained. 1 H NMR(400 MHz, CDCl3)δ7.88 (s, 1H), 7.81 (d, J = 1.8 Hz, 1H), 7.51 (s, 1H), 7.47–7.30(m, 5H), 7.28–7.19 (m, 2H), 1.13 (s, 36H). 13 C NMR (101 MHz, CDCl3)δ145.6,141.8, 138.9, 138.8, 136.9, 133.9, 133.9, 130.6, 129.6, 129.3, 128.2, 127.6,127.5, 121.7,117.2, 31.5, 30.2, 29.4, 29.4. HRMS (ESI) m / z: [M+H] + Calcd for [C 31 H 47N2P2] + 509.3209; Found 509.3211. Example 6 Preparation of 1,4-bis(2-(di-tert-butylphosphino)phenyl)-1H-imidazole: Following the procedure of Example 2, diphenylphosphine chloride was replaced with an equimolar amount of diadamantylphosphine chloride (12 mmol, 4.04 g). The reaction time was extended to 24 hours. Other conditions were the same as in Example 2. A white solid 1,4-bis(2-(di-tert-butylphosphino)phenyl)-1H-imidazole (2.87 g, yield 70%) was obtained. 1 H NMR (400 MHz, CDCl3)δ7.88 (s, 1H), 7.81 (d, J = 1.8 Hz,1H), 7.52 (s, 1H), 7.45–7.32 (m, 6H), 7.23 (ddd, J = 6.9, 5.0,1.4 Hz, 1H), 2.00–1.89 (m, 12H), 1.73–1.59 (m, 48H). 13 C NMR (101 MHz, CDCl3)δ145.9, 142.7,141.8, 141.4, 138.9, 136.2, 130.5, 129.6, 129.4, 128.2, 127.7, 127.6, 127.5,121.8, 117.2, 50.4, 49.1, 44.0, 43.7, 43.3, 43.0, 38.7, 37.1, 29.8, 29.8.HRMS (ESI) m / z: [M+H] + Calculated for [C 55 H 71 N2P2] + 821.5087; Found 821.5084. Example 7 Preparation of 1,4-bis(2-bromophenyl)-1H-imidazole: Following the procedure in Example 1, Pd(dppf)Cl2 was replaced with Pd(PPh3)4 (1.16 g, 1.0 mmol, 10 mol%), the base was replaced with potassium carbonate (2.76 g, 20 mmol, 2.0 equivalents), and the solvent was replaced with toluene / water (80 mL / 20 mL). The reaction temperature was raised to 100 °C, and the reaction was stirred for 20 hours. Post-treatment and purification were the same as in Example 1, yielding a white solid product, 1,4-bis(2-bromophenyl)-1H-imidazole (3.10 g, yield 82%). The NMR and HRMS data of the product were consistent with those of Example 1.

[0016] Example 8 Following the procedure of Example 1, Pd(dppf)Cl2 was replaced with Pd2(dba)3 (0.46 g, 0.5 mmol, 5 mol% as Pd), the base was replaced with cesium carbonate (8.15 g, 25 mmol, 2.5 equivalents), and the solvent was replaced with xylene / water (60 mL / 20 mL). The reaction temperature was raised to 110 °C, and the reaction was stirred for 16 hours. The post-treatment and purification methods were the same as in Example 1, yielding a white solid product (3.02 g, 80% yield). The NMR and HRMS data of the product were consistent with those of Example 1.

[0017] Example 9 Following the procedure of Example 1, Pd(dppf)Cl2 was replaced with Pd(OAc)2 (0.11 g, 0.5 mmol, 5 mol%), the base was replaced with sodium tert-butoxide (2.88 g, 30 mmol, 3.0 equivalents), and the solvent was replaced with 1,4-dioxane / water (80 mL / 20 mL). The reaction temperature was lowered to 80 °C, and the reaction was stirred for 24 hours. Post-treatment and purification were performed as in Example 1, yielding a white solid product (2.84 g, yield 75%). The NMR and HRMS data of the product were consistent with those of Example 1.

[0018] Example 10 Following the procedure of Example 1, Pd(dppf)Cl2 was replaced with Pd(PPh3)2Cl2 (0.70 g, 1.0 mmol, 10 mol%), the base was replaced with sodium carbonate (2.65 g, 25 mmol, 2.5 equivalents), and the solvent was replaced with ethylene glycol dimethyl ether / water (60 mL / 20 mL). The reaction temperature was maintained at 90 °C, and the reaction was stirred for 18 hours. The post-treatment and purification methods were the same as in Example 1, yielding a white solid product (3.21 g, yield 85%). The NMR and HRMS data of the product were consistent with those of Example 1.

[0019] Example 11 Following the procedure of Example 1, Pd(dppf)Cl2 was replaced with Pd(dba)2 (0.57 g, 1.0 mmol, 10 mol%), the base was replaced with potassium hydroxide (1.68 g, 30 mmol, 3.0 equivalents), and the solvent was replaced with tetrahydrofuran / water (80 mL / 20 mL). The reaction temperature was lowered to 70 °C, and the reaction was stirred for 24 hours. Post-treatment and purification were performed as in Example 1, yielding a white solid product (2.80 g, yield 74%). The NMR and HRMS data of the product were consistent with those of Example 1.

[0020] Example 12 Following the procedure of Example 1, the base was replaced with sodium phosphate (4.10 g, 25 mmol, 2.5 equivalents), and the solvent was replaced with toluene / water (80 mL / 20 mL). The reaction temperature was raised to 100°C, and the reaction was stirred for 12 hours. Post-treatment and purification were performed as in Example 1, yielding a white solid product (3.06 g, yield 81%). The NMR and HRMS data of the product were consistent with those of Example 1.

[0021] Application examples Under a nitrogen atmosphere, 2-bromoanisole (0.5 mmol), phenylboronic acid (0.75 mmol), Pd₂(dba)₃ (0.005 mmol, 1 mol%), the ligand prepared in Example 2 (0.01 mmol, 2 mol%), potassium carbonate (1.0 mmol), and a toluene / water mixture (3 mL / 0.3 mL) were added to a reaction flask. The reaction was stirred at 80 °C for 6 hours. After the reaction was completed, the mixture was cooled, extracted, the organic phase was concentrated, and purified by column chromatography to obtain 2-methoxybiphenyl with a yield of 97%. 1 H NMR (400 MHz, CDCl3)δ7.74–7.65 (m, 2H), 7.55 (tt, J = 6.6, 1.0 Hz, 2H), 7.51–7.41(m, 3H), 7.22–7.07 (m, 2H), 3.91 (s, 3H). 13 C NMR (101 MHz, CDCl3)δ156.4, 138.5, 130.8,130.6, 129.5, 128.5, 127.9, 126.8, 120.7, 111.2, 55.4. Comparative Example 1 Under a nitrogen atmosphere, 2-bromoanisole (0.5 mmol), phenylboronic acid (0.75 mmol), Pd₂(dba)₂ (0.005 mmol, 1 mol%), potassium carbonate (1.0 mmol), and a toluene / water mixture (3 mL / 0.3 mL) were added to a reaction flask. No ligands were added. The reaction was stirred at 80 °C for 6 hours. Post-treatment was the same as in the application example. Purification by column chromatography yielded 2-methoxybiphenyl, with a separation yield of only 11%.

[0022] Comparative Example 2 Under a nitrogen atmosphere, 2-bromoanisole (0.5 mmol), phenylboronic acid (0.75 mmol), Pd₂(dba)₃ (0.005 mmol, 1 mol%), 1,1'-bis(diphenylphosphine)ferrocene (DPPF, 0.01 mmol, 2 mol%), potassium carbonate (1.0 mmol), and a toluene / water mixture (3 mL / 0.3 mL) were added to a reaction flask. The reaction mixture was stirred at 80 °C for 6 hours. Post-treatment was the same as in the application example. Purification by column chromatography yielded 2-methoxybiphenyl in 65% separation.

[0023] Comparative Example 3 Under a nitrogen atmosphere, 2-bromoanisole (0.5 mmol), phenylboronic acid (0.75 mmol), Pd₂(dba)₃ (0.005 mmol, 1 mol%), the ligand prepared in Example 4 (0.01 mmol, 2 mol%), potassium carbonate (1.0 mmol), and a toluene / water mixture (3 mL / 0.3 mL) were added to a reaction flask. The reaction was stirred at 80 °C for 6 hours. Post-treatment was the same as in the application example. Purification by column chromatography yielded 2-methoxybiphenyl in 95% separation. serial number ligands Pd / ligand molar ratio Separation yield Application examples Example 2 Ligand 1:2 97% Comparative Example 1 ligand-free — 11% Comparative Example 2 DPPF 1:2 65% Comparative Example 3 Example 4 Ligand 1:2 95%

[0024] In summary, compared to DPPF, the imidazole skeleton bisphosphine ligand of this invention effectively reduces the reaction energy barrier of aryl halide oxidative addition by virtue of the electron-withdrawing conjugation effect of the five-membered nitrogen heteroaryl ring. Moreover, the substituent on the phosphorus can be flexibly switched between aryl and alkyl groups to precisely control steric hindrance, accelerate the C–C reduction elimination elementary step, and ultimately achieve a Suzuki coupling catalytic yield higher than that of DPPF.

Claims

1. A bisphosphonate compound containing an imidazole skeleton, characterized in that: Its general structural formula is as follows: Wherein, R is phenyl, cyclohexyl, isopropyl, tert-butyl, or adamantyl.

2. The method for preparing the bisphosphonate compound containing an imidazole skeleton as described in claim 1, characterized in that: Includes the following steps: S1. Under nitrogen protection, 1H-imidazol-5-borate pinacol ester was coupled with 2-bromoiodobenzene, palladium catalyst, and base in a solvent to prepare 1,4-bis(2-bromophenyl)-1H-imidazol intermediate. S2. Under inert gas protection, the 1,4-bis(2-bromophenyl)-1H-imidazolium intermediate obtained in step S1 is dissolved in an anhydrous solvent, reacted with an organolithium reagent for lithium-bromine exchange, and then reacted with phosphine chloride. After post-treatment, the target product is obtained.

3. The preparation method according to claim 2, characterized in that: In step S1, the molar ratio of 1H-imidazol-5-boronic acid pinacol ester to 2-bromoiodobenzene is 1:2.0-3.5, the coupling reaction temperature is 60-120℃, and the reaction time is 6-24 hours.

4. The preparation method according to claim 3, characterized in that: In step S1, the palladium catalyst is any one of Pd(dppf)Cl2, Pd(PPh3)4, Pd2(dba)3, Pd(OAc)2, Pd(PPh3)2Cl2, and Pd(dba)2; the amount used is 0.5-15 mol of 1H-imidazol-5-boronic acid pinacol ester.

5. The preparation method according to claim 4, characterized in that: In step S1, the alkali is any one of potassium phosphate, potassium carbonate, cesium carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, sodium tert-butoxide, potassium tert-butoxide, sodium phosphate, sodium acetate, and triethylamine; the amount of alkali used is 1-5 equivalents of 1H-imidazol-5-boronic acid pinacol ester.

6. The preparation method according to claim 5, characterized in that: In step S1, the solvent is a mixture of organic solvent and water, with a volume ratio of organic solvent to water of 10:1 to 2:1; the organic solvent is one of 1,4-dioxane, toluene, xylene, ethylene glycol dimethyl ether, N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran.

7. The preparation method according to claim 6, characterized in that: In step S2, the organolithium reagent is n-butyllithium; the anhydrous solvent is selected from tetrahydrofuran, diethyl ether, methyl tert-butyl ether, and 1,4-dioxane; the reaction temperature is -78℃ to 0℃; and the molar ratio of 1,4-bis(2-bromophenyl)-1H-imidazolium, organolithium reagent, and phosphine chloride is 1:(2.2-2.8):(2.2-2.8).

8. The application of the bisphosphonate compound containing an imidazole skeleton as described in claim 1 in transition metal catalytic reactions, characterized in that: It is used as a metal ligand to construct metal catalytic systems.

Images