Sulfinate-modified n-heterocyclic carbene chelated palladium complexes, methods of synthesis and use thereof

Abstract

This invention belongs to the field of organometallic complex synthesis technology, specifically relating to a sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex, its synthesis method, and its applications. This type of complex uses a dimer of a fused imidazole / thiazolium oxide quaternary ammonium salt or a fused imidazole / thiazide oxide quaternary ammonium salt and a nitrogen heterocyclic carbene palladium complex as a starting material. Under the action of an alkaline substance, the C-S bond undergoes oxidative cleavage, and the carbene is positioned at the metal center, oxidized to give a +2 valence S sulfinate, which is then further chelated and coordinated. In the Suzuki-Miruaya coupling catalytic reaction, the weakly coordinated sulfinate ion can react with the borate substrate, activating it and replacing the sulfinate ion at the palladium metal center. After the product is reduced and eliminated, the sulfinate ion can re-coordinate with the palladium metal center, stabilizing it, thus exhibiting excellent catalytic activity.

Description

Technical Field

[0001] This invention belongs to the field of metal-organic complex synthesis technology, specifically relating to a sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex, its synthesis method, and its application. Background Technology

[0002] Nitrogen heterocyclic carbene metal complexes play a crucial role in organometallic catalysis, particularly in metal catalysis. On one hand, nitrogen heterocyclic carbene ligands can form strong MC-coordinate bonds with the metal center, stabilizing it. On the other hand, the nitrogen substituents in nitrogen heterocyclic carbene ligands are easily modified, allowing for the modulation of the metal center environment through alterations in the carbene ligand's electron configuration and steric hindrance, thereby optimizing catalytic activity. Introducing coordinable heteroatoms into the nitrogen substituents further enables the preparation and catalytic applications of chelate, pincer-type, and polynuclear metal complexes.

[0003] Among heteroatom-modified nitrogen heterocyclic carbene complexes, those modified by N, O, and P atoms and their complexes are relatively well-developed, while analogs modified by S atoms are relatively rare [Coord. Chem. Rev. 2011, 255, 574]. S atoms can exist in various oxidation states between -2 and +6. Complexes involving coordination with nitrogen heterocyclic carbenes modified by -2-valent thioethers, thiophenes, and mercapto groups, 0-valent sulfoxides, and +4-valent sulfonic acids have been reported. However, the catalytic applications of nitrogen heterocyclic carbene ligands modified by sulfur atoms in other valence states and their metal complexes remain to be explored. Summary of the Invention

[0004] To expand the applications of S-atom-modified nitrogen heterocyclic carbene complexes, this invention provides a class of nitrogen heterocyclic carbene palladium complexes modified with +2 valence S, i.e., sulfinate anions. In this complex, the sulfinate-modified nitrogen heterocyclic carbene is chelated and coordinated with the palladium metal center via the carbene carbon and the sulfur atom of the sulfinate anion, and its structural formula is as follows:

[0005]

[0006] In the formula, R1 is any one of methyl, ethyl, isopropyl, and benzyl; R2 is any one of H, methyl, phenyl, and benzo[a] fused ring; NHC is any one of 1,3-diisopropylbenzimidazole-2-carbene, 1,3-dimethylimidazole-2-carbene, and 1,3-bis(2,5,6-trimethylphenyl)imidazole-2-carbene; X is any one of Cl, Br, and I; and n is 1 or 2.

[0007] This invention also provides a method for synthesizing the above-mentioned sulfinate-modified nitrogen heterocyclic carbene chelate cyclic palladium complex, the reaction route of which is as follows:

[0008]

[0009] In the formula, Base refers to an alkaline substance.

[0010] R1 is any one of methyl, ethyl, isopropyl, and benzyl; R2 is any one of H, methyl, phenyl, and benzo[a]-fused ring; NHC is any one of 1,3-diisopropylbenzimidazole-2-carbene, 1,3-dimethylimidazol-2-carbene, and 1,3-bis(2,5,6-trimethylphenyl)imidazol-2-carbene; X is any one of Cl, Br, and I; and n is 1 or 2.

[0011] Using fused imidazole / thiazolium oxide quaternary ammonium salt or fused imidazole / thiazide oxide quaternary ammonium salt and nitrogen heterocyclic carbene palladium complex dimers as raw materials, and any one or more mixtures of dichloromethane, acetonitrile, and tetrahydrofuran as solvents, under the action of alkaline substances, the CS bonds in the raw materials are oxidized and broken, and the oxidized sulfinate anions chelate and coordinate to generate sulfinic acid modified nitrogen heterocyclic carbene chelated cyclic palladium metal complexes.

[0012] The alkaline substance is any one of silver oxide, potassium carbonate, or potassium tert-butoxide.

[0013] The structural formulas of the above-mentioned fused imidazole / oxythiazolium quaternary ammonium salts or fused imidazole / oxythiazolium quaternary ammonium salts are shown in the following formulas:

[0014]

[0015] The present invention also provides a method for synthesizing the above-mentioned fused imidazole / thiazolium quaternary ammonium salt or fused imidazole / thiazolium quaternary ammonium salt: fused (benzo)imidazole / thiazolium quaternary ammonium salt or fused (benzo)imidazole / thiazolium quaternary ammonium salt is dissolved in a solvent with a haloalkane and reacted at a reaction temperature (preferably at 90°C for 12 hours).

[0016] Furthermore, the solvent is any one or a mixture of toluene, tetrahydrofuran, acetonitrile, dimethylformamide, and dimethyl sulfoxide.

[0017] After successfully obtaining and fully characterizing the above-mentioned complexes, the probes in these complexes i Pr2-bimy carbene carbon 13 The C-shift was used to analyze the electron-donating ability of the left-side sulfinic acid-modified N-heterocyclic carbene bidentate ligand (HEP method). The results showed that the electron-donating ability of this type of sulfinic acid-modified N-heterocyclic carbene bidentate ligand was only better than that of N^N ligands, and weaker than that of C^N and C^N ligands. carbene ^C carbene and (sp 3 )C^C carbene The ligand indicates S(O2)^C carbene Its electron-donating ability is relatively weak.

[0018] This invention also provides the application of the above-mentioned sulfinic acid-modified nitrogen heterocyclic carbene chelate cyclic palladium complex in the catalytic Suzuki-Miyaura coupling reaction.

[0019]

[0020]

[0021] The sulfite-modified nitrogen-containing heterocyclic carbene chelate palladium complexes of this invention generally exhibit higher catalytic activity in the Suzuki-Miyaura reaction. The inventors hypothesize that during the catalytic reaction, the weakly coordinated sulfite ion can react with the borate substrate, activating the aryl and alkenyl groups and replacing the sulfite ion at the palladium metal center. After the product is reduced and eliminated, the sulfite ion can then re-coordinate with the palladium metal center, stabilizing it.

[0022] Advantages and technical effects of this invention: This invention successfully prepares, for the first time, a nitrogen-containing heterocyclic carbene chelate palladium complex modified with +2 valence S through a rare oxidative insertion reaction involving fused imidazole / thiazolium oxide quaternary ammonium salt or fused imidazole / thiazide oxide quaternary ammonium salt. Under Suzuki-Miruaya coupled catalytic conditions, the weakly coordinated sulfinate anion can react with the borate substrate, activating it and replacing the sulfinate anion at the palladium metal center. After reductive elimination of the product, the sulfinate anion can re-coordinate with the palladium metal center, stabilizing it, thus exhibiting excellent catalytic activity. Attached image description:

[0023] Figure 1 This is a single-crystal structure diagram of compound 2.

[0024] Figure 2 This is a single-crystal structure diagram of compound 3.

[0025] Figure 3 The present invention is S(O2)^C carbene Schematic diagram of electron-donating ability of bidentate ligands and other representative bidentate ligands (based on...) i Pr2-bimy probe ligand 13 C NMR displacement). Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments.

[0027] The synthetic routes for complexes 2-4 in the following examples are as follows:

[0028]

[0029] In the formula, R1 is any one of methyl, ethyl, isopropyl, and benzyl; R2 is any one of H, methyl, phenyl, and benzo[a] fused ring; NHC is any one of 1,3-diisopropylbenzimidazole-2-carbene, 1,3-dimethylimidazole-2-carbene, and 1,3-bis(2,5,6-trimethylphenyl)imidazole-2-carbene; X is any one of Cl, Br, and I; and n is 1 or 2.

[0030] Example 1

[0031]

[0032] (1) Synthesis of condensed imidazole / thiazole quaternary ammonium salt 1a

[0033] Imidazole (5.21 g, 76.66 mmol) and methyl acrylate (25.60 mL, 283.64 mmol) were placed in a 50 mL pressure-resistant tube and stirred at 80 °C for 1 day. Methyl acrylate was removed by vacuum distillation to obtain a transparent oil. The transparent oil (2.11 g, 13.94 mmol) and 1,2-dibromoethane (28.70 mL, 333.17 mmol) were placed in a 50 mL round-bottom flask and reacted at 90 °C for 12 h. 1,2-dibromoethane was removed by vacuum distillation using an oil pump. The residual 1,2-dibromoethane was removed by washing with diethyl ether. Silica gel column chromatography (eluent: dichloromethane / methanol = 50 / 1, V / V) was performed to obtain a yellow oil.

[0034] The above-mentioned yellow oily substance (4.35 g, 12.73 mmol) and potassium thiocyanate (12.37 g, 97.18 mmol) were dissolved in acetonitrile and stirred at room temperature for 2 days. Then, sodium hydroxide (3.30 mL, 20.37 mmol) was added and reacted at room temperature for 1 day. The mixture was then heated to 80 °C and reacted for another day. After filtration, acetonitrile was removed by vacuum distillation. Dichloromethane was added to dissolve the product and then filtered. Dichloromethane was removed by vacuum distillation and the mixture was then subjected to silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1 / 1, V / V) to obtain a yellow oily product, which was then mixed with imidazole / thiazole (1.14 g, 71%).

[0035] The condensed imidazole / thiazole (126.18 mg, 1.00 mmol) and hydrogen peroxide (187 μL, 6.10 mmol) were dissolved in water (2 mL) and reacted in a 10 mL Schlenk tube at 60 °C for 1 day. After extraction with dichloromethane, the dichloromethane was removed by vacuum distillation and treated with silica gel column chromatography (eluent: dichloromethane / methanol = 25 / 1, V / V) to obtain the condensed imidazole / thiazole oxide (58.1 mg, 41%).

[0036] The thiocyanate and imidazole / thiazolium oxychloride (98 mg, 0.68 mmol) and benzyl bromide (291 μL, 2.45 mmol) were dissolved in a mixture of acetonitrile (2 mL) and toluene (5 mL), placed in a round-bottom flask, and stirred at 90 °C for 1 day. After removing the solvent by vacuum distillation, the residue was washed with diethyl ether (4 × 3 mL) to obtain the product.

[0037] 1a: White solid, yield 79%. 1 H NMR (400MHz, D2O): δ 7.93 (d, 3 J=9Hz,2H,Imi-H),7.55(S,5H,Ar-H),5.64(m, 3 J = 18 Hz, 2H, NCH2), 5.02 (m, 3 J = 13 Hz, 1H, NCH2), 4.87 (m, 3 J = 7Hz, 1H, NCH2), 4.22(m, 3 J = 12 Hz, 1H, SOCH2), 3.99 (m, 3 J = 10Hz, 1H, SOCH2); 13 C{ 1 H}NMR(100MHz,D2O): δ148.4(NCN),131.5,130.2,129.8,129.6(Ar-C),121.2(Imi-C),56.7,54.3,46.8(CH2).Anal.Calcd.for C 12 H 13 BrN2OS:C 46.02,H 4.18,N 8.94; found:C 45.88,H 4.34,N8.91.MS(ESI):m / z 233[M-Br] + .

[0038] (2) Synthesis of carbene complex 2

[0039] Add 1a (63 mg, 0.20 mmol) and [PdBr2( i Pr2-bimy)]2 (94 mg, 0.10 mmol), silver oxide (46 mg, 0.20 mmol), and dichloromethane (20 mL) were reacted at room temperature in the dark for 1 day. After filtration through diatomaceous earth and removal of solvent under vacuum, the mixture was subjected to silica gel column chromatography (eluent: dichloromethane / methanol = 100 / 1, V / V).

[0040] 2: Pale yellow solid, yield 25%. 1H NMR (400MHz, CDCl3): δ7.62-7.58(m,2H,Ar-H),7.42-7.35(m,5H,Ar-H),7.22-7.19(m,2H,Ar-H),6.91(d, 3 J = 1Hz, 1H, Imi-H), 6.78 (d, 3 J=2Hz,1H,Imi-H),5.92(s,2H,NCH2),5.83(m, 3 J = 14 Hz, 2H, NCH), 4.56 (m, 3 J = 5Hz, 2H, NCH2), 2.90 (m, 3 J = 5 Hz, 2H, SO2CH2), 1.84 (m, 3 J = 7Hz, 6H, CH3), 1.66 (d, 3 J = 4Hz, 6H, CH3); 13 C{ 1 ¹H NMR (100MHz, CDCl₃): δ 177.5 (C carbene-benz ),169.9(C carbene-imi ),137.3,137.1,134.2,134.1,129.6,128.8,128.6,128.5,122.9,122.8,122.6,122. 4,122.1(Ar-C),113.8(Imi-C),64.2,55.9,55.1,47.1,47.0,21.8,21.5,21.4(CH,CH2 and CH3).Anal.Calcd.forC 25 H 31 BrN4O2PdS:C 47.07,H 4.90,N 8.78; found:C 46.88,H 4.65,N 8.53.MS(ESI):m / z557[M-Br] + .

[0041] Example 2

[0042]

[0043] (1) Synthesis of condensed imidazole / oxythiazide quaternary ammonium salt 1b

[0044] Imidazole (3 g, 44.70 mmol) and methyl acrylate (15.60 mL, 173.70 mmol) were placed in a 25 mL pressure-resistant tube and stirred at 80 °C for 3 hours. Methyl acrylate was removed by vacuum distillation to obtain the product. Then, 1,3-dibromopropane (13.50 mL, 133 mmol) was added, and the mixture was reacted at 90 °C for 12 hours. 1,3-dibromopropane was removed by vacuum distillation using an oil pump. The residue of 1,3-dibromopropane was removed by washing with diethyl ether. The product was then subjected to silica gel column chromatography (eluent: dichloromethane / methanol = 50 / 1, V / V) to obtain a yellow oily substance.

[0045] The above reaction product (4.18 g, 11.70 mmol) and potassium thiocyanate (11.40 g, 117.40 mmol) were dissolved in acetonitrile and stirred at 60 °C for 2 days. After cooling to room temperature, sodium hydroxide (3.00 mL, 18.70 mmol) was added and the mixture was reacted at room temperature for 1 day. The mixture was then heated to 80 °C and reacted for another day. After filtration, acetonitrile was removed by vacuum distillation. Dichloromethane was added to dissolve the mixture and filtered. Dichloromethane was removed by vacuum distillation and silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1 / 1, V / V) was performed to obtain a reddish-black liquid, viscous and imidazole / thiazide (509.30 mg, 31%).

[0046] The condensed imidazole / thiazide (318.90 mg, 2.27 mmol) and hydrogen peroxide (473 μL, 15.44 mmol) were dissolved in water (3 mL) and reacted at 60 °C for 1 day. After extraction with dichloromethane, the mixture was subjected to silica gel column chromatography (eluent: dichloromethane / methanol = 70 / 1, V / V) to obtain the condensed imidazole / thiazide oxide (142.00 mg, 40%).

[0047] The condensate, imidazole / thiazide oxide (115 mg, 1.36 mmol) and benzyl bromide (580 μL, 4.89 mmol) were dissolved in toluene (10 mL), placed in a sealed tube, and stirred at 90 °C for 12 hours. After removing the toluene by vacuum distillation, the residue was washed with diethyl ether (2 × 5 mL) to obtain the product.

[0048] 1b: White solid, yield 99%. 1 H NMR (300MHz, MeOD): δ8.09-8.06(m,2H,Imi-H),7.51-7.39(m,5H,Ar-H),5.66(m, 3 J = 21 Hz, 2H, NCH2), 4.58 (m, 3 J = 7 Hz, 1H, NCH2), 4.18 (m, 3 J = 15 Hz, 1H, NCH2), 3.63 (m, 3 J = 8 Hz, 2H, SOCH2), 2.53 (m, 3J = 25 Hz, 2H, CH2); 13 C{ 1 H}NMR(75MHz,MeOD): δ141.7(NCN),133.8,128.9,128.6,124.7(Ar-C),123.8(Imi-C),50.9,47.4,44.7,13.5(CH2).Anal.Calcd.for C 13 H 15 BrN2OS:C 47.72,H 4.62,N 8.56; found:C 47.89,H4.55N 8.20.MS(ESI):m / z 247[M-Br] + .

[0049] (2) Synthesis of carbene complex 3

[0050] Add 1b (82.80 mg, 0.25 mmol) and [PdBr2( i Pr2-bimy)]2 (107 mg, 0.11 mmol), silver oxide (59 mg, 0.25 mmol), and dichloromethane (20 mL) were reacted at room temperature in the dark for 1 day. After filtration through diatomaceous earth and removal of solvent under vacuum, the mixture was subjected to silica gel column chromatography (eluent: dichloromethane / methanol = 100 / 1, V / V).

[0051] 3: Pale yellow solid, yield 15%. 1 H NMR (300MHz, CDCl3): δ7.64-7.36(m,7H,Ar-H),7.22-7.19(m,2H,Ar-H),6.93(m, 3 J = 5Hz, 2H, Imi-H), 6.24 (m, 3 J = 9Hz, 1H, NCH2), 5.93 (m, 3 J = 14 Hz, 2H, NCH), 5.54 (m, 3 J = 16 Hz, 1H, NCH2), 5.33 (m, 3 J = 9 Hz, 1H, NCH2), 4.18 (m, 3 J = 10 Hz, 1H, NCH2), 2.59 (m, 3 J = 14 Hz, 2H, SO2CH2), 2.28 (m, 3 J = 14 Hz, 1H, CH2), 1.92 (d, 3 J = 3Hz, 3H, CH3), 1.80 (d, 3 J = 3Hz, 3H, CH3), 1.75 (d, 3J = 4Hz, 3H, CH3), 1.64 (d, 3 J = 3Hz, 3H, CH3); 13 C{ 1 ¹H NMR (75MHz, CDCl₃): δ 178.6 (C carbene-benz ),171.4(C carbene-imi ), 137.1, 134.2 (Ar-C, two peaks overlap), 129.8, 129.1, 128.7, 128.6, 123.8, 122.8, 121.3 (Ar-C), 113.9, 113.8 (Imi-C), 62.2, 55.7, 55.2, 54.9, 48.2, 27.2, 21.7 (CH, CH2 & CH3), 21.5 (CH3, two peaks overlap), 21.4 (CH2). Anal.Calcd.for C 26 H 33 BrN4O2PdS:C 47.90,H 5.10,N 8.59; found:C 47.82,H 4.83,N8.65.MS(ESI):m / z 571[M-Br] + .

[0052] Example 3

[0053]

[0054] (1) Synthesis of fused 4-methylimidazolium / thiazide quaternary ammonium salt 1c

[0055] 4-Methylimidazole (2.50 g, 30.45 mmol) and methyl acrylate (10.20 mL, 112.67 mmol) were placed in a 25 mL pressure-resistant tube and stirred at 80 °C for 30 minutes. Methyl acrylate was removed by vacuum distillation to obtain the product. The product (1.16 g, 6.88 mmol) was added to 1,3-dibromopropane (4.68 mL, 43.99 mmol), and reacted at 90 °C for 5 h. 1,3-dibromopropane was removed by vacuum distillation using an oil pump. The product was then subjected to silica gel column chromatography (eluent: dichloromethane / methanol = 50 / 1, V / V) to obtain a yellow oily substance.

[0056] The above reaction product (1.07 g, 3.00 mmol) and potassium thiocyanate (2.90 g, 30.00 mmol) were dissolved in acetonitrile and stirred at 60 °C for 2 days. After cooling to room temperature, sodium hydroxide (0.77 mL, 4.80 mmol) was added and the mixture was reacted at room temperature for 1 day. The mixture was then heated to 80 °C and reacted for another day. After filtration, acetonitrile was removed by vacuum distillation. The mixture was dissolved in dichloromethane and filtered. The solution was then subjected to silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 1 / 1, V / V) to obtain a reddish-black liquid, which was viscous and contained imidazole / thiazide (300.50 mg, 65%).

[0057] The condensed 4-methylimidazole / thiazide (123.90 mg, 0.80 mmol) and hydrogen peroxide (162 μL, 4.80 mmol) were dissolved in a mixture of acetonitrile (2 mL) and water (2 mL), reacted at 60 °C for 1 day, acetonitrile was removed by vacuum distillation, and after extraction with dichloromethane, silica gel column chromatography (eluent: dichloromethane / methanol = 70 / 1, V / V) was performed to obtain condensed 4-methylimidazole / thiazide oxidase (61.00 mg, 41%).

[0058] The condensate and 4-methylimidazole / thiazide oxide (45.60 mg, 0.27 mmol) and benzyl bromide (63.60 μL, 0.54 mmol) were dissolved in a 10 mL round-bottom flask of toluene and stirred at 90 °C for 2 days. After removing the toluene by vacuum distillation, the residue was washed with toluene (3 × 10 mL) to obtain the product.

[0059] 1c: Yellow solid, yield 94%. 1 H NMR (400MHz, D2O): δ7.62(s,1H,Imi-H),7.50-7.46(m,5H,Ar-H),5.65(m, 3 J = 22 Hz, 2H, NCH2), 4.53 (m, 3 J = 9Hz, 1H, NCH2), 4.13(m, 3 J = 15 Hz, 1H, SOCH2), 3.74 (m, 3 J = 10 Hz, 1H, NCH2), 3.44 (m, 3 J = 14 Hz, 1H, SOCH2), 2.77 (m, 3 J = 15 Hz, 1H, CH2), 2.65 (m, 3 J=8Hz,1H,CH2),2.38(s,3H,CH3); 13 C{ 1H}NMR(100MHz,D2O): δ137.9(NCN),134.8(Imi-C),132.6,129.4,129.3,128.4,127 .0(Ar-C),121.9(Imi-C),51.9,44.6,43.9,13.1(CH2),8.3(CH3).Anal.Calcd.for C 14 H 17 BrN2OS:C 49.27,H 5.02,N 8.21; found:C48.99,H 5.26,N 8.32.MS(ESI):m / z 261[M-Br] + .

[0060] (2) Synthesis of carbene complex 4

[0061] Add 1c (68.30 mg, 0.20 mmol) and [PdBr2( i Pr2-bimy)]2 (94 mg, 0.10 mmol), silver oxide (46 mg, 0.20 mmol), and dichloromethane (20 mL) were reacted at room temperature in the dark for 1 day. The mixture was then filtered through diatomaceous earth and concentrated. The solvent was removed by vacuum filtration through diatomaceous earth filtration, followed by silica gel column chromatography (eluent: dichloromethane / methanol = 100 / 1, V / V) to obtain the product.

[0062] 4: Yellow solid, yield 18%. 1 H NMR (400MHz, CDCl3): δ7.63-7.36(m,7H,Ar-H),7.21-7.19(m,2H,Ar-H),6.67(s,1H,Imi-H),6.16(m, 3 J = 10 Hz, 1H, NCH2), 5.95 (m, 3 J = 9 Hz, 2H, NCH), 5.47 (m, 3 J = 16 Hz, 1H, NCH2), 5.25 (m, 3 J = 10 Hz, 1H, NCH2), 4.14 (m, 3 J = 12 Hz, 1H, NCH2), 2.57 (m, 3 J = 6 Hz, 2H, CH2), 2.30 (m, 3 J=9Hz,1H,SO2CH2),2.15(s,3H,CH3),1.93(m, 3 J = 2Hz, 3H, CH3), 1.91 (m, 3 J=2Hz,4H,CH3,SO2CH2),1.77(m, 3J = 15 Hz, 3H, CH3), 1.63 (m, 3 J = 4Hz, 3H, CH3); 13 C{ 1 ¹H NMR (100MHz, CDCl₃): δ 178.9 (C carbene-benz ),171.0(C carbene-imi ),137.4,137.2,134.2,134.1,129.8,129.5,129.4,129.0,128.9,128.7,122.8,122.7,120.7,120.6,113.9(Ar-C,Imi- C),113.8(Imi-C),62.0,55.5,55.2,55.1,54.9,44.8,26.3,21.7,21.5,21.4(CH,CH2&CH3),9.60(CH3).Anal.Calcd.for C 27 H 35 BrN4O2PdS:C 48.69,H 5.30,N8.41; found:C 49.01,H 5.21,N 8.33.MS(ESI):m / z 585[M-Br] + .

[0063] Example 4: Electron-donating ability of the sulfinic acid-modified nitrogen heterocyclic carbene bidentate ligand of the present invention

[0064] Complexes 2-4 all contain a benzimidazole-derived compound. i Pr2-bimy probe ligand, its 13 C carbene Nuclear magnetic resonance shifts can be used to determine this type of S(O2)^C carbene Electron-donating ability of bidentate ligands (HEP method). Comparing complexes 3 and 4 with n=2, complex 4... 13 C carbene-benz At lower field positions (Table 1), it is indicated that methyl-containing sulfinic acid imidazole carbenes in the skeleton have a stronger electron-donating ability; complexes 2 and 3 with the same imidazole skeleton but different carbon numbers... 13 C carbene-benz Shift comparisons indicate that chelated palladium complexes with more cyclic carbons exhibit stronger electron-donating capabilities. Compared to other reported bidentate ligands ( Figure 3 ), this type of S(O2)^C carbene Didentate ligands have weaker electron-donating ability than C. carbene ^C carbene and anionic C carbeneIt is a C(sp2 / sp3) ligand, but stronger than N^N and C^N ligands [Inorg.Chem.2014,53,10964; Dalton.Trans.2018,47,7830; Dalton Trans.2019,48,7546].

[0065] Table 1

[0066]

[0067] Example 5 Catalytic application of the complex of the present invention

[0068] In an air atmosphere, aryl halide (0.20 mmol), phenylboronic acid (0.30 mmol) or pinacol ester of vinylboronate (0.30 mmol), cyclopalladium complex 2 (1 mol%), K3PO4·3H2O (0.40 mmol), and EtOH (1 mL) solvent and dodecane (0.20 mmol) internal standard were added to a reaction flask. After heating the reaction for 24 h, a drop of the reaction solution was taken and diluted to 2 mL with dichloromethane. Quantitative analysis was performed by gas chromatography.

[0069] The results showed that for the Suzuki-Miruaya coupling reaction involving four different substituted bromoaromatic substrates, the cyclic palladium complex 2 exhibited moderate to good catalytic activity in the coupling reaction with p-bromobenzonitrile, 4-bromoacetophenone and phenylboronic acid as substrates (Table 2). Compared with the C^N and N^N cyclic palladium complexes reported in the literature, the catalytic activity was higher and the reaction conditions were more advantageous.

[0070] Table 2

[0071]

Claims

1. A class of sulfinate-modified nitrogen-heterocyclic carbene chelate palladium complexes, characterized in that: The structure of the complex is shown in the following formula: 、 、 。 2. A method for synthesizing the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex as described in claim 1, characterized in that: The synthesis method is as follows: using sulfoxide-modified quaternary ammonium salt and nitrogen heterocyclic carbene palladium complex dimer as raw materials, under the action of alkaline substance silver oxide, the CS bond in the raw materials is oxidized and broken, and the oxidized sulfite anion is chelated and coordinated to generate sulfite-modified nitrogen heterocyclic carbene chelated cyclic palladium metal complex. The structural formula of the sulfoxide-modified quaternary ammonium salt is as follows: ， The dimer structure of the nitrogen-containing heterocyclic carbene palladium complex is as follows: 。 3. The method for synthesizing the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex as described in claim 2, characterized in that: In a solvent, a sulfoxide-modified quaternary ammonium salt, a nitrogen heterocyclic carbene palladium complex dimer, and a basic substance are reacted at room temperature with stirring to obtain a sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex.

4. The method for synthesizing the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex as described in claim 3, characterized in that: The solvent is any one or a mixture of dichloromethane, acetonitrile, and tetrahydrofuran.

5. The method for synthesizing the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex as described in claim 2, characterized in that: The preparation method of sulfoxide-modified quaternary ammonium salt is as follows: condensed imidazole / thiazolium oxide or condensed imidazole / thiazide oxide is dissolved with benzyl bromide in a solvent and reacted at 90°C for 12 hours. The structural formulas of the fused imidazole / oxythiazole and oxythiazide are as follows: .

6. The method for synthesizing the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex as described in claim 5, characterized in that: The solvent for synthesizing sulfoxide-modified quaternary ammonium salts is any one or a mixture of toluene, tetrahydrofuran, acetonitrile, dimethylformamide, and dimethyl sulfoxide.

7. An application of the sulfinate-modified nitrogen heterocyclic carbene chelate palladium complex according to claim 1, characterized in that: The complex is used as a catalyst for the Suzuki-Miruaya coupling reaction.

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