Nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complex and its synthesis method and application

Abstract

The present invention belongs to the technical field of synthesis of metal organic complexes, and specifically relates to a nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclic palladium complexes and their synthesis methods and applications. This type of complex is formed by in situ oxidation and chelation of benzylamine or substituted benzylamine in the presence of palladium acetate in air, and then coordinated by nitrogen heterocyclic carbene. This type of Schiff base type C sp2 ^N sp2 The bidentate ligand has a strong electron-donating ability, which increases the electron cloud density of the metal center and more effectively catalyzes the Suzuki-Miruaya coupling reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthesis of metal organic complexes, and particularly relates to a nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complex, synthesis method and application thereof. Background Art

[0002] In the fields of organometallic chemistry and coordination chemistry, arylamino groups are common C sp2 ^N sp3 Chelating ligands are widely used for their excellent catalytic effect in cross-coupling reactions [Chemical Science.2013,4,916; Journal of the American Chemical Society.2014,136,4149]. Harting and colleagues found that under catalytic conditions, these ligands can be rapidly reduced and eliminated, promoting the generation of active Pd(0) species to activate the inert CX bond [Journal of the American Chemical Society.2013,135,3740]. In addition, the chelate coordination of arylamino groups with palladium metal effectively activates the aromatic carbon atoms, making it possible to carry out cyclic amidation, halogenation and alkenylation reactions in the presence of stoichiometric or even catalytic amounts of Pd.

[0003] The arylamino group and palladium metal are C sp2 ^N sp3 Chelate coordination complexes are widely available, but the corresponding Schiff base type C sp2 ^N sp2 The number of cyclopalladium complexes is relatively limited. This may be because most Schiff base ligands need to be generated by condensation reaction of aldehydes, ketones and amines, and then coordinate with the metal center and cyclize to prepare C sp2 ^N sp2 The preparation method of palladium ring complexes is relatively complicated [WO 2015 / 024403 Al]. Summary of the Invention

[0004] In order to conveniently synthesize nitrogen heterocyclic carbene C sp2 ^N sp2 The present invention provides a kind of palladalide complex, which is prepared by in-situ oxidation and chelation of benzylamine or substituted benzylamine in the presence of palladium acetate in air, and then coordinated by nitrogen heterocyclic carbene to form a nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complex. In this complex, the palladium metal center is composed of carbene, bromine and Schiff base type C sp2 ^N sp2Ligand coordination, the structural formula is as follows:

[0005]

[0006] In the formula, R is any one of hydrogen, fluorine, methyl, tert-butyl, and trifluoromethyl, R1 is hydrogen or methyl, and R2 is hydrogen or methyl.

[0007] The present invention also provides the above-mentioned nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 The synthesis method of the bidentate cyclopalladium complex is as follows:

[0008]

[0009] (1) In a solvent, benzylamine or substituted benzylamine and palladium acetate are stirred at the reaction temperature. After the reaction is completed, C sp2 ^N sp2 Solutions of chelated palladium cyclodimers.

[0010] The molar ratio of benzylamine or substituted benzylamine to palladium acetate is 1:1, the solvent is a mixture of any one or more of dimethyl sulfoxide, acetonitrile, and tetrahydrofuran, the reaction temperature is room temperature to 90° C., and the reaction time is 24 h.

[0011] (2) No need to separate, sp2 ^N sp2 1,3-diisopropylbenzimidazole bromide is added to the solution of chelated cyclic palladium dimer, reacted at the reaction temperature, and separated by column chromatography to obtain nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complexes.

[0012] Among them, C sp2 ^N sp2 The molar ratio of the chelated palladium cyclodimer to 1,3-diisopropylbenzimidazolium bromide is 1:1. The reaction temperature is room temperature to 90°C, and the reaction time is 12 to 24 hours.

[0013] After the successful acquisition and complete characterization of the above complexes, the probes in these complexes i Pr2-bimy carbene carbon 13 C displacement can be used to analyze the right side C sp2 ^N sp2 The electron donating ability of bidentate ligands (HEP method) showed that this type of C sp2 ^N sp2 The electron-donating ability of bidentate ligands is better than that of common neutral N^N, anionic N^N and C carbene ^C carbene , but weaker than C sp3 ^Ccarbene Ligands and a class of 1,2,3-triazole-derived unusual carbene C^C bidentate ligands.

[0014] The present invention also provides the above-mentioned nitrogen heterocyclic carbene C sp2 ^N sp2 Application of cyclopalladium complexes in catalyzing Suzuki-Miyaura coupling reactions.

[0015]

[0016] The catalytic results showed that the complex had high catalytic activity for p-bromoacetophenone, with catalytic yields above 85%. The catalytic activity of different catalysts for both p-bromoacetophenone and p-chloroacetophenone increased with the increase of C sp2 ^N sp2 The electron-donating capacity of the ligand gradually increases, indicating that this type of nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Catalytic activity of bidentate palladium ring complexes and their C sp2 ^N sp2 The HEP2 values ​​of bidentate ligands were positively correlated.

[0017] Advantages and technical effects of the present invention: The present invention provides a method for preparing a nitrogen heterocyclic carbene-Schiff base type C based on the in-situ oxidation and chelation coordination of benzylamine or substituted benzylamine in the air under palladium acetate conditions, and then coordinated with nitrogen heterocyclic carbene. sp2 ^N sp2 A convenient method for the preparation of bidentate cyclopalladium complexes. i Pr2-bimy carbene carbon 13 C displacement can also be used to analyze the right side C sp2 ^N sp2 The electron-donating ability of bidentate ligands is tested and the results show that this type of Schiff base C sp2 ^N sp2 The bidentate ligand has a strong electron-donating ability, which increases the electron cloud density of the metal center, thereby catalyzing the Suzuki-Miyaura coupling reaction, and its catalytic activity increases with the C sp2 ^N sp2 The electron donating capacity of the ligand increases gradually. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the single crystal structure diagram of compound 7.

[0019] Figure 2 C of the present invention sp2 ^N sp2 Schematic diagram of the electron-donating ability of bidentate ligands and other representative bidentate ligands (based on i Pr2-bimy probe ligand13 C NMR shift). DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the embodiments.

[0021] The synthetic routes of the complexes in the following examples are as follows:

[0022]

[0023] Example 1

[0024] 1,3-Diisopropylbenzimidazole bromide was prepared by adding benzimidazole (591 mg, 5 mmol), potassium carbonate (760 mg, 5.5 mmol), and acetonitrile (30 mL) to a 50 mL round-bottom flask. The mixture was stirred at room temperature for 1 hour, followed by the addition of 2-bromopropane (1.40 mL, 15 mmol). The reaction mixture was stirred at reflux for 24 hours, followed by the addition of 2-bromopropane (1.40 mL, 15 mmol), and the mixture was stirred at reflux for 72 hours. The solvent was removed by distillation under reduced pressure, and dichloromethane was added to the residue. The filtrate was collected by filtration, and the solvent was removed in vacuo to yield a yellow oil, which was washed with ethyl acetate to yield a white powder (765 mg, 2.7 mmol, 54%).

[0025]

[0026] To a 25 mL round-bottom flask, benzylamine (44 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and dimethyl sulfoxide (20 mL) were added and stirred at room temperature for 24 hours. 1,3-Diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0027] 1: light yellow powder, yield 40%. 1 H NMR (400 MHz, CDCl3): δ 9.25 (d, 3 J=10Hz,1H,NH),8.38(d, 3 J=11Hz,1H,NCH),7.65-7.63(m,2H,Ar-H),7.41(d, 3 J=7Hz,1H,Ar-H),7.28-7.26(m,2H,Ar-H),7.03(t, 3 J=7Hz,1H,Ar-H),6.93(t, 3J=7Hz,1H,Ar-H),6.27(d, 3 J=7Hz,1H,Ar-H),6.01(d, 3 J=7Hz,2H,NCH),1.73(d, 3 J=7Hz,6H,CH3),1.60(d, 3 J = 7 Hz, 6H, CH3). 13 C{ 1 H}NMR (100 MHz, CDCl3): 184.12 (C carbene ),180.2(NCH),148.8,137.39,137.04,134.2,132.2,129.5,124.7,122.9,113.4(Ar-C),55.2,21.5,21.4(CH and CH3).MS(ESI):m / z412[M-Br] + .

[0028] Example 2

[0029]

[0030] To a 25 mL round-bottom flask, p-fluorobenzylamine (46 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and acetonitrile (20 mL) were added and stirred at 60°C for 24 hours. 1,3-Diisopropylbenzimidazole bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0031] 2: light yellow powder, yield 41%. 1 H NMR (300 MHz, CDCl3): δ 9.20 (d, 3 J=9Hz,1H,NH),8.36(d, 3 J=9Hz,1H,NCH),7.66-7.62(m,2H,Ar-H),7.44-7.40(m,1H,Ar-H),7.30-7.26(m,2H,Ar-H),6.71(t, 3 J=7Hz,1H,Ar-H),5.96(m, 3 J=7Hz,3H,Ar-H&NCH),1.73(d, 3 J=7Hz,6H,CH3),1.62(d, 3 J = 7 Hz, 6H, CH3). 13 C{1 H}NMR (75MHz,CDCl3):182.81(C carbene ),178.9(NCH),164.4(d, 1 J=246Hz),163.9(d, 4 J=3Hz),145.2,134.2,131.1(d, 3 J=9Hz),123.5(d, 2 J=18Hz),123.1,113.4,111.4(d, 2 J=21Hz), (Ar-C), 55.2, 21.5 (CH, and CH3). 19 F NMR(282MHz, CDCl3): δ-105.7(s,1F).MS(ESI): m / z 430[M-Br] + .

[0032] Example 3

[0033]

[0034] To a 25 mL round-bottom flask, 4-(trifluoromethyl)benzylamine (57 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and tetrahydrofuran (20 mL) were added and stirred at 70°C for 24 hours. 1,3-Diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0035] 3: light yellow powder, yield 40%. 1 H NMR (300 MHz, CDCl3): δ 9.66 (d, 3 J=10Hz,1H,NH),8.48(d, 3 J=11Hz,1H,NCH),7.66-7.64(m,2H,Ar-H),7.51(d, 3 J=8Hz,1H,Ar-H),7.32-7.28(m,2H,Ar-H),6.52(d, 3 J=9Hz,1H,Ar-H),5.93(d, 3 J=7Hz,2H,NCH),1.73(d, 3 J=7Hz,6H,CH3),1.59(d, 3 J = 7 Hz, 6H, CH3). 13 C{1 H}NMR (75MHz,CDCl3):181.96(C carbene ),179.5(NCH),160.8,151.9,134.1(d, 4 J=3Hz),131.4(d, 2 J=37Hz),129.0,125.5(d, 1 J=271Hz),123.2,121.6(d, 3 J=3Hz),113.3(Ar-C),55.2,54.1,21.7,21.5,21.4,21.3(CH and CH3). 19 F NMR(282MHz, CDCl3): δ-63.2(s,1F).MS(ESI): m / z 480[M-Br] + .

[0036] Example 4

[0037]

[0038] To a 25 mL round-bottom flask, p-methylbenzylamine (51 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and dimethyl sulfoxide (20 mL) were added and stirred at 90°C for 24 hours. 1,3-Diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0039] 4: light yellow powder, yield 47%. 1 H NMR (400 MHz, CDCl3): δ 9.09 (d, 3 J=9Hz,1H,NH),8.33(d, 3 J=11Hz,1H,NCH),7.65(br-s,2H,Ar-H),7.31-7.26(m,3H,Ar-H),6.85(d, 3 J=7Hz,1H,Ar-H),6.13(s,1H,Ar-H),6.01(d, 3 J=7Hz,2H,NCH),2.09(s,3H,CH3),1.74(d, 3 J=7Hz,6H,CH3),1.61(d, 3 J = 7 Hz, 6H, CH3). 13 C{ 1H}NMR (100 MHz, CDCl3): 184.43 (C carbene ),179.7(NCH),160.5,146.2,142.8,137.9,134.2,129.3,125.3,122.8,113.4(Ar-C),55.1,22.7,21.4(CHand CH3).MS(ESI):m / z 426[M-Br] + .

[0040] Example 5

[0041]

[0042] To a 25 mL round-bottom flask, 4-tert-butylbenzylamine (71 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and dimethyl sulfoxide (20 mL) were added and stirred at 90°C for 24 hours. 1,3-Diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0043] 5: light yellow powder, yield 40%. 1 H NMR (300 MHz, CDCl3): δ 9.14 (d, 3 J=11Hz,1H,NH),8.34(d, 3 J=11Hz,1H,NCH),7.65-7.62(m,2H,Ar-H),7.35-7.26(m,3H,Ar-H),7.04(d, 3 J=8Hz,1H,Ar-H),6.23(d, 3 J=11Hz,1H,Ar-H),6.04(d, 3 J=7Hz,2H,NCH),1.73(d, 3 J=7Hz,6H,CH3),1.60(d, 3 J=7Hz,6H,CH3),1.00(s,9H,CH3). 13 C{ 1 H}NMR (75MHz,CDCl3):184.52(C carbene),179.5(NCH),160.3,155.4,146.2,134.3,134.1,129.1,122.9,121.4,113.3(Ar-C),55.1,35.5,31.6,21.5,21.3(CH and CH3).MS(ESI):m / z 468[M-Br] + .

[0044] Example 6

[0045]

[0046] To a 25 mL round-bottom flask, α-methylbenzylamine (51 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and dimethyl sulfoxide (20 mL) were added and stirred at 90°C for 24 hours. 1,3-Diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) was then added and the reaction continued for 24 hours. The solvent was removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0047] 6: light yellow powder, yield 30%. 1 H NMR (300MHz, CDCl3): δ8.77(s,1H,NH),7.65-7.62(m,2H,Ar-H),7.30-7.26(m,3H,Ar-H),7.03(t, 3 J=7Hz,1H,Ar-H),6.93(t, 3 J=7Hz,1H,Ar-H),6.29(d, 3 J=7Hz,1H,Ar-H),6.01(m, 3 J=7Hz,2H,Ar-H&NCH),2.43(s,3H,CCH3),1.73(d, 3 J=7Hz,6H,NCCH3),1.60(d, 3 J = 7 Hz, 6H, CH3). 13 C{ 1 H}NMR (75MHz,CDCl3):187.10(C carbene ),185.6(NCH),160.0,148.2,137.2,134.3,132.2,128.7,124.6,122.8,113.4(Ar-C),55.1,22.9,21.56,21.46(CH and CH3).MS(ESI):m / z426[M-Br] + .

[0048] Example 7

[0049]

[0050] To a 25 mL round-bottom flask, add N-methylbenzylamine (52 μL, 0.40 mmol), palladium acetate (90 mg, 0.40 mmol), and dimethyl sulfoxide (20 mL). Stir at 90°C for 24 hours. Then, add 1,3-diisopropylbenzimidazolium bromide (114 mg, 0.40 mmol) and continue the reaction for another 24 hours. The solvent is removed by distillation under reduced pressure to obtain a crude product. After extraction three times with dichloromethane and water, the product is purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain the product.

[0051] 7: light yellow powder, yield 56%. 1 H NMR (300MHz, CDCl3): δ8.12(s,1H,NCH),7.65-7.62(m,2H,Ar-H),7.32-7.26(m,2H,Ar-H),7.01(t, 3 J=7Hz,1H,Ar-H),6.85(t, 3 J=7Hz,1H,Ar-H),6.15(d, 3 J=7Hz,1H,Ar-H),6.02(m, 3 J=7Hz,2H,NCH),3.78(s,2H,NCH3),1.73(d, 3 J=7Hz,6H,CH3),1.58(d, 3 J = 7 Hz, 6H, CH3). 13 C{ 1 H}NMR (75MHz,CDCl3):183.75(C carbene ),175.1(NCH),158.9,147.9,136.8,134.3,130.9,128.2,124.6,122.8,113.4(Ar-C),55.2,48.7,21.48,21.34(CH and CH3).MS(ESI):m / z 426[M-Br] + .

[0052] Example 8 Present invention C sp2 ^N sp2 Electron-donating ability of bidentate ligands

[0053] Complexes 1-7 all contain a benzimidazole-derived i Pr2-bimy probe ligand, which 13 Ccarbene NMR shifts can be used to determine the C sp2 ^N sp2 Electron-donating ability of bidentate ligand (HEP method). Schiff base type C synthesized from unsubstituted benzylamine sp2 ^N sp2 Taking the bidentate complex 1 as the standard, when there is a substituent on the benzene ring, the HEP2 value of the resulting complex increases in the order of 3 < 2 < 1 < 4 < 5, among which the HEP2 value of complex 5 is the largest, which is due to the electron-donating effect (+I) of the tert-butyl electron-donating group in the ligand. On the contrary, the HEP2 value of complex 3 is the smallest, which is due to the electron-withdrawing effect (-I) of the trifluoromethyl group. When an electron-donating methyl group is substituted at the α position of the imine NH, the HEP2 value is the largest, indicating that its electron-donating ability is the strongest. In terms of inductive effect, the electron-pushing effect produced by the ortho-methyl substitution is stronger than the electron-pushing effect produced by the para-tert-butyl substituent on the benzene ring. Direct N-methylation leads to C-N-methylbenzylamine-derived sp2 ^N sp2 The electron-donating ability of the ligand is weakened, which is due to the steric hindrance of the N-substituent, which weakens the coordination effect of the ligand and leads to a decrease in the HEP2 value reflected by the carbene ligand (Table 1).

[0054] Table 1

[0055]

[0056] Compared with other bidentate ligands reported ( Figure 2 ), this type of C sp2 ^N sp2 The electron-donating ability of bidentate ligands is stronger than that of neutral N^N ligands, C NHC ^C NHC Ligands, anionic N^N ligands and S(O2)^C NHC ligand, but weaker than C NHC ^C sp3 Bidentate ligands and 1,2,3-triazole-derived unusual carbene C MIC ^C sp2 Ligand. [Inorganic Chemistry.2014,53,10964;Dalton Transactions.2018,47,7830;Dalton Transactions.2019,48,7546;Dalton Transactions.2023,52:2223-2226].

[0057] Example 9 Catalytic Application of the Complex of the Present Invention

[0058] Under air atmosphere, aryl halide (0.20 mmol), phenylboronic acid (0.30 mmol), [Pd] catalyst 1-7 (1 mol%), K2CO3 (0.40 mmol), EtOH (2 mL) solvent and internal standard dodecane (0.20 mmol) were added to the reaction flask. After reacting at 100°C for 20 h, the reaction solution was aspirated and diluted with ethyl acetate to 1 mL, and quantitative analysis was performed by gas chromatography.

[0059] Table 2

[0060]

[0061] The catalytic activity of complexes 1-7 towards p-bromoacetophenone is higher than that towards p-chloroacetophenone, and the catalytic yields are all above 85%. sp2 ^N sp2 The bidentate ligand has a strong electron-donating ability, which increases the electron cloud density of the metal center, thereby facilitating the oxidative addition reaction of the substrate. In addition, for both substrates, the catalytic activity of different catalysts increases with the C sp2 ^N sp2 The electron-donating capacity of the ligand gradually increases, indicating that this type of Schiff base bidentate C sp2 ^N sp2 The catalytic activities of the complexes were positively correlated with the HEP2 values ​​of their ligands (Table 2). Among them, the catalytic yield of 7f with an imine chelate derived from tert-butylbenzylamine was the highest, at 98% and 35%, respectively.

Claims

1. A type of nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 The bidentate palladium ring complex is characterized in that The structural formula of the complex is shown below: In the formula, R is any one of hydrogen, fluorine, methyl, tert-butyl, and trifluoromethyl, R1 is hydrogen or methyl, and R2 is hydrogen or methyl.

2. A nitrogen heterocyclic carbene-Schiff base type C as claimed in claim 1 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: The synthesis method steps are as follows: (1) Benzylamine or substituted benzylamine and palladium acetate are reacted under air conditions. Benzylamine or substituted benzylamine is in situ oxidized and coordinated with palladium metal to generate C sp2 ^N sp2 Chelated palladium cyclodimer; (2) The dimer of step (1) reacts with 1,3-diisopropylbenzimidazole bromide to generate nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complexes.

3. The nitrogen heterocyclic carbene-Schiff base type C according to claim 2 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: Generate C sp2 ^N sp2 The method for chelating the palladium ring dimer is as follows: in a solvent, benzylamine or substituted benzylamine and palladium acetate are stirred to react, and after the reaction is completed, C sp2 ^N sp2 Solutions of chelated palladium cyclodimers.

4. The nitrogen heterocyclic carbene-Schiff base type C according to claim 3 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: The molar ratio of benzylamine or substituted benzylamine to palladium acetate is 1:1, the reaction temperature is room temperature to 90° C., and the reaction time is 24 h.

5. The nitrogen heterocyclic carbene-Schiff base type C according to claim 3 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: The solvent is a mixture of any one or more of dimethyl sulfoxide, acetonitrile and tetrahydrofuran.

6. The nitrogen heterocyclic carbene-Schiff base type C according to claim 2 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: Generate nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 The method for preparing bidentate cyclopalladium complex is: sp2 ^N sp2 1,3-diisopropylbenzimidazole bromide was added to the solution of chelated cyclic palladium dimer to react, and separated by column chromatography to obtain nitrogen heterocyclic carbene-Schiff base type C sp2 ^N sp2 Bidentate cyclopalladium complexes.

7. The nitrogen heterocyclic carbene-Schiff base type C according to claim 6. sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: C sp2 ^N sp2 The molar ratio of the chelated palladium cyclodimer to 1,3-diisopropylbenzimidazolium bromide is 1:

1.

8. The nitrogen heterocyclic carbene-Schiff base type C according to claim 6 sp2 ^N sp2 The method for synthesizing a bidentate palladium ring complex is characterized in that: The reaction temperature is room temperature to 90°C, and the reaction time is 12 to 24 hours.

9. A nitrogen heterocyclic carbene-Schiff base type C according to claim 1 sp2 ^N sp2 The application of the bidentate palladium ring complex is characterized in that The complex is used as a catalyst for the Suzuki-Miruaya coupling reaction.

Images