Tridentate pincer manganese complex, preparation method thereof and application in alcohol dehydrogenation olefination reaction

Abstract

The present invention discloses a tridentate pincer manganese complex, a preparation method thereof and an application thereof in alcohol dehydrogenation olefination reaction. The tridentate pincer manganese complex has the following structure: #imgabs0# wherein R is selected from a group containing C1-C 20 The method for preparing the tridentate manganese pincer complex comprises: using 8-aminoquinaldine as a raw material to synthesize a tridentate pincer ligand through multiple steps, and coordinating the tridentate pincer ligand with pentacarbonyl manganese bromide to prepare a novel tridentate manganese pincer complex. The tridentate manganese pincer complex prepared by the present invention has a novel skeleton structure, a simple and efficient preparation method, and high practicality. The obtained manganese complex has high activity as a catalyst in the dehydrogenation olefination reaction of alcohols and has very important application prospects.

Description

Technical Field

[0001] The invention relates to a tridentate pincer manganese complex and a preparation method thereof, as well as application thereof in alcohol dehydrogenation olefination reaction, and belongs to the technical field of organic chemical synthesis. Background Art

[0002] Efficient and highly selective covalent bond formation is a hot topic and a frontier in organic synthetic chemistry research. Homogeneous transition metal-catalyzed activation of inert chemical bonds has garnered widespread attention in recent years due to its relatively mild reaction conditions and excellent selectivity. Homogeneous transition metal catalysts generally refer to transition metal complexes, which consist of a metal center and a ligand. Currently, transition metal complexes used in catalytic reactions are primarily based on precious metals such as ruthenium, iridium, palladium, platinum, and rhodium. While these complexes exhibit high catalytic activity and excellent selectivity, they also have limitations, such as limited reserves, limited variety, and high cost. Abundant manganese metal, due to its low toxicity, abundance, and low cost, has attracted researchers' attention, leading to increasing research on the synthesis and application of manganese metal complexes. The catalytic activity and reaction selectivity of metal complexes are closely related to the electronic and steric effects of the ligands, necessitating the design and synthesis of ligand backbones with diverse types and coordination environments. Currently, the most widely used ligands are pincer ligands based on pyridine, bipyridine, or heteroatom-containing alkyl chains. As shown in the following structural formula, PNP-type manganese complex 1 (Manganese-Catalyzed Environmentally Benign Dehydrogenative Coupling of Alcohols and Amines to Form Aldimines and H2: A Catalytic and Mechanistic Study. J. Am. Chem. Soc. 2016, 138, 4298) and NNP-type manganese complex 2 (Direct Synthesis of Amides by Dehydrogenative Coupling of Amines with either Alcohols or Esters: Manganese Pincer Complex as Catalyst. Angew. Chem., Int. Ed. 2017, 56, 14992) and PN5P-type pincer manganese complex 3 (Manganese-Catalyzed Multicomponent Synthesis of Pyrimidines from Alcohols) synthesized from tridentate pyridine ligands and metallic manganese. andAmidines.Angew.Chem.,Int.Ed.2017,56,1663) showed certain catalytic activity in dehydrogenation reaction.The bipyridine-type manganese complex 4 (Highly Selective Hydroboration of Alkenes, Ketones and Aldehydes Catalyzed by a Well-Defined Manganese Complex. Angew. Chem., Int. Ed. 2016, 55, 14369) in which all the coordinating atoms are nitrogen atoms and the manganese complex 5 (Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes. J. Am. Chem. Soc. 2016, 138, 8809) with alkyl chain structure pincer ligands also showed activity in hydrogenation reactions.

[0003]

[0004] Currently, there are no reports of pincer manganese complexes formed by quinoline-based ligands and abundant manganese metal. Therefore, the development of a new tridentate pincer manganese complex is of great research significance for expanding the types and applications of manganese metal catalysts and exploring the efficient construction of chemical bonds, which will help develop new green and efficient synthetic reactions and methods. Summary of the Invention

[0005] The main purpose of the present invention is to provide a novel tridentate pincer manganese complex and a preparation method thereof, so as to overcome the deficiencies of the prior art.

[0006] Another object of the present invention is to provide the use of the tridentate pincer manganese complex in alcohol dehydrogenation olefination reaction.

[0007] To achieve the above-mentioned purpose, the technical solutions adopted by the present invention include:

[0008] In some embodiments of the present invention, a tridentate pincer manganese complex is provided, which has a structure as shown in formula (I):

[0009]

[0010] Wherein, R is selected from the group consisting of C1-C 20 alkyl or aryl.

[0011] Some embodiments of the present invention also provide a method for preparing a tridentate pincer manganese complex, which comprises:

[0012] preparing a tridentate pincer ligand having a structure as shown in formula (II);

[0013]

[0014] reacting the tridentate pincer ligand with a metal manganese catalyst precursor to obtain a tridentate pincer manganese complex;

[0015] Wherein, R is selected from the group consisting of C1-C 20 The metal manganese catalyst precursor includes Mn(CO)5Br.

[0016] Some embodiments of the present invention also provide a tridentate pincer manganese complex prepared by the aforementioned preparation method.

[0017] Some embodiments of the present invention also provide the use of the aforementioned tridentate pincer manganese complex as a metal catalyst in the dehydrogenation of alcohols.

[0018] Accordingly, some embodiments of the present invention further provide a catalyst for alcohol dehydrogenation olefination reaction, which comprises the aforementioned tridentate pincer manganese complex.

[0019] Furthermore, some embodiments of the present invention also provide a method for preparing olefins by dehydrogenating an alcohol compound, which comprises:

[0020] heating an alcohol compound, a sulfone compound, a catalyst, and an alkaline substance under reflux in a fifth solvent to prepare an olefin compound; wherein the catalyst comprises the aforementioned catalyst for alcohol dehydrogenation olefination reaction or the aforementioned tridentate pincer manganese complex;

[0021] The structural formula of the alcohol compound is The structural formula of sulfone compounds is The structural formula of olefin compounds is

[0022] Among them, R 3 is an aryl group, R 1 Selected from C1-C 20 Any one of alkyl, aryl and hydrogen, R 2 Any one selected from alkyl and aryl groups.

[0023] Compared with the prior art, the present invention has at least the following advantages:

[0024] 1) The preparation method of the novel tridentate pincer manganese complex provided by the present invention has a simple route, mild reaction conditions and high yield;

[0025] 2) The tridentate pincer manganese complex synthesized in the present invention has a new quinoline skeleton structure, adjustable substituents, high catalytic activity, can achieve efficient dehydrogenation of alcohols, and has high future application value;

[0026] 3) The manganese catalyst provided by the present invention has high reaction activity in the alcohol dehydrogenation reaction to prepare olefins, and the catalyst dosage is low. DETAILED DESCRIPTION

[0027] To overcome the shortcomings of the prior art, the inventors of this case, through designing experiments, proposed the technical solution of the present invention. This solution primarily uses 8-aminoquinaldine as a raw material to synthesize a tridentate pincer ligand with a novel framework. This ligand is then reacted with a metallic manganese precursor to prepare a novel tridentate pincer manganese complex. This technical solution, its implementation process, and its principles are further explained below.

[0028] One aspect of the present invention provides a novel tridentate pincer manganese complex having a structure as shown in formula (I):

[0029]

[0030] Wherein, R is selected from the group consisting of C1-C 20 Alkyl, aryl, etc.

[0031] Another aspect of the present invention provides a method for preparing a novel tridentate pincer manganese complex, which mainly comprises: in a protective atmosphere, using 8-aminoquinaldine as a starting material, and synthesizing a series of tridentate chelating manganese complexes with N- H A tridentate pincer manganese complex with a new NP-type quinaldine skeleton.

[0032] In some specific embodiments, the method for preparing the tridentate pincer manganese complex comprises:

[0033] preparing a tridentate pincer ligand having a structure as shown in formula (II);

[0034]

[0035] reacting the tridentate pincer ligand with a metal manganese catalyst precursor to obtain a tridentate pincer manganese complex;

[0036] Wherein, R is selected from the group consisting of C1-C 20 The metal manganese catalyst precursor includes Mn(CO)5Br.

[0037] In some preferred embodiments, the method for preparing the tridentate pincer ligand comprises:

[0038] In a protective atmosphere, heating a mixed reaction system comprising 8-aminoquinaldine, a benzyl compound, a first base, and a first solvent to 45-100° C. and reacting for 12-72 hours to obtain a substituted 8-aminoquinaldine;

[0039] The substituted 8-aminoquinaldine is mixed with a second solvent, and the temperature is lowered to -78 to -45°C. A second base is added, and the mixture is stirred for 1 to 2 hours. A phosphine chloride reagent is then added, and the mixture is heated to 25 to 80°C and reacted for 12 to 48 hours. After the reaction is completed, a BH3·THF solution is added, and the mixture is stirred for 2 to 12 hours. After post-treatment, a compound having a structure shown in formula (III) is obtained.

[0040] Under nitrogen protection, a compound having a structure as shown in formula (III), an amine and a third solvent are mixed and heated to 30-150° C. for reaction for 12-24 hours to obtain a tridentate pincer ligand having a structure as shown in formula (II).

[0041] The benzyl compound includes any one or a combination of two of benzyl chloride, benzyl bromide, etc., but is not limited thereto.

[0042] Furthermore, the structure of the substituted 8-aminoquinaldine is shown in formula (IV):

[0043]

[0044]

[0045] Furthermore, the structural formula of the phosphine-chloride reagent is RRPCl, wherein R is selected from the group consisting of C1-C 20 Alkyl, aryl, etc.

[0046] Specifically, the synthesis method of the compound represented by formula (III) comprises the following steps:

[0047]

[0048] Furthermore, the preparation process of the tridentate pincer ligand having the structure shown in formula (II) of the present invention further includes:

[0049]

[0050] Furthermore, when R is isopropyl, the structural formula of the substituted 8-aminoquinaldine is:

[0051]

[0052] And its NMR characterization data is: 31 P NMR (162 MHz, CDCl3) δ 35.17. 1H NMR (400MHz, CDCl3) δ8.01(d,J=8.4Hz,1H),7.49–7.21(m,7H),7.05(d,J=7.8Hz,1H),6.68(d,J=7.5Hz,1H),6.35 (s,1H),4.52(s,2H),3.38(d,J=10.9Hz,2H),2.20–2.02(m,2H),1.12(td,J=14.0,7.1Hz,12H),0.89–0.10(m,3H). 13 C NMR (151MHz, CDCl3) δ151.85 (d, J = 6.5Hz), 144.02, 139.12, 137.40, 136.45, 128.62, 127.49, 127.27, 127.01, 123 .04(d,J=2.0Hz),114.04,105.27,47.74,30.94(d,J=26.0Hz),31.02,30.85,21.85,21.65,16.94(d,J=10.3Hz).

[0053] Furthermore, when R is tert-butyl, the structural formula of the substituted 8-aminoquinaldine is:

[0054]

[0055] And its NMR characterization data is: 31 P NMR (162 MHz, CDCl3) δ 46.89. 1 H NMR (400MHz, CDCl3) δ7.98(d,J=8.5Hz,1H),7.63(d,J=8.5Hz,1H),7.44–7.23(m,6H),7.03(d,J=8.1Hz,1H),6.63(d, J=7.6Hz,1H),6.51(s,1H),4.55(d,J=5.1Hz,2H),3.49(d,J=12.2Hz,2H),1.28(d,J=12.6Hz,18H),1.08–0.07(m,3H). 13 C NMR (151MHz, CDCl3) δ152.82 (d, J = 3.0Hz), 144.05, 139.36, 137.12, 135.83, 128.57, 127 .25,127.15,127.08,124.06,114.10,105.21,47.56,32.98,32.81,30.05,29.90,28.20.

[0056] Furthermore, when R is a cyclohexyl group, the structural formula of the substituted 8-aminoquinaldine is:

[0057]

[0058] And its NMR characterization data is: 31 P NMR (162 MHz, CDCl3) δ 27.61. 1 H NMR(400MHz, CDCl3)δ8.00(d,J=8.4Hz,1H),7.52–7.20(m,7H),7.05(d,J=7.9Hz,1H),6.66(d,J=7.5Hz,1H), 6.41(s,1H),4.54(s,2H),3.37(d,J=11.1Hz,2H),1.96–1.50(m,12H),1.45–1.03(m,10H),0.95–0.04(m,3H). 13 C NMR(151MHz, CDCl3)δ152.14(d,J=6.2Hz),144.07,139.13,137.42,136.36,128.6,127.43(d,J=9.1Hz),127.24,127.07,1 23.32(d,J=2.2Hz),114.13,105.31,47.72,31.62,31.42,30.91,30.73,26.83,26.79,26.76,26.74,26.72,26.65,25.92.

[0059] Furthermore, when R is phenyl, the structural formula of the substituted 8-aminoquinaldine is:

[0060]

[0061] And its NMR characterization data is: 31 P NMR (162 MHz, CDCl3) δ 17.78. 1 H NMR(400MHz, CDCl3) δ7.90(d,J=8.4Hz,1H),7.78–7.65(m,4H),7.44–7.19(m,13H),6.96(d,J=8.1Hz,1H ),6.49(d,J=7.6Hz,1H),5.90(s,1H),4.39(d,J=4.3Hz,2H),3.96(d,J=11.8Hz,2H),1.59–0.53(m,3H). 13C NMR (101MHz, CDCl3) δ150.21 (d, J = 5.2Hz), 144.09, 139.24, 136.19, 132.65 (d, J = 9.2Hz), 131.12 (d, J = 2.3Hz), 129.2 0,128.54(dd,J=11.2,10.1Hz),127.44,127.29,127.06,123.25(d,J=3.5Hz),113.77,105.10,47.33,36.67,36.35.

[0062] In some preferred embodiments, the molar ratio of the 8-aminoquinaldine, the benzyl compound and the first base is 1:1:1 to 1:5:10.

[0063] Furthermore, the molar ratio of the substituted 8-aminoquinaldine to the second base is 1:0.5 to 1:10.

[0064] Furthermore, the molar ratio of the substituted 8-aminoquinaldine to the phosphine chloride reagent is 1:0.5 to 1:10.

[0065] Furthermore, the first base includes any one or a combination of two or more of sodium hydroxide, sodium tert-butoxide, potassium tert-butoxide, potassium methoxide, sodium methoxide, potassium ethoxide, sodium ethoxide, sodium carbonate, potassium hydroxide, potassium carbonate, sodium hydride, potassium hydride and potassium phosphate, but is not limited thereto.

[0066] Furthermore, the first solvent includes any one or a combination of two or more of N,N-dimethylformamide, ether, dichloromethane, methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, acetone, tetrahydrofuran and toluene, but is not limited thereto.

[0067] Furthermore, the second base includes any one or a combination of two or more of n-butyllithium, tert-butyllithium, sec-butyllithium, lithium diisopropylamide, sodium bis(trimethylsilyl)amide, lithium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, potassium tert-butoxide, sodium tert-butoxide, sodium hydride, potassium hydride, etc., but is not limited thereto.

[0068] Furthermore, the second solvent includes any one or a combination of two or more of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, toluene, n-hexane and 1,4-dioxane, but is not limited thereto.

[0069] Furthermore, the molar ratio of the compound having the structure shown in formula (III) to the amine is 1:1 to 1:20.

[0070] Furthermore, the amine includes any one or a combination of two or more of diethylamine, triethylamine, DABCO (1,4-Diazabicyclo[2.2.2]octane), aniline, benzylamine, etc., but is not limited thereto.

[0071] Furthermore, the third solvent includes any one or a combination of two or more of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, toluene, xylene, n-hexane and 1,4-dioxane, but is not limited thereto.

[0072] In some preferred embodiments, the preparation method comprises: mixing the tridentate pincer ligand and a metal manganese catalyst precursor in a fourth solvent, and heating the mixture for reaction to obtain a tridentate pincer manganese complex.

[0073] Furthermore, the molar ratio of the tridentate pincer ligand to the metal manganese catalyst precursor is 1:2 to 10:1, preferably 1:1 to 3:1.

[0074] Furthermore, the fourth solvent includes any one or a combination of two or more of methanol, ethanol, tetrahydrofuran, toluene, benzene, dichloromethane, ether, n-hexane and 1,4-dioxane, but is not limited thereto.

[0075] Furthermore, the heating temperature is 30 to 130° C., preferably 50 to 90° C., and the reaction time is 12 to 72 hours.

[0076] As a preferred technical solution, the preparation method comprises: dissolving the concentrated tridentate pincer ligand solution prepared in the previous step in a fourth solvent and transferring the solution into a reaction flask, adding a metal manganese catalyst precursor, Mn(CO)5Br, and heating the solution to 30-130°C for a reaction of 12-72 hours. After the reaction is completed, the solution is cooled to room temperature, the solvent is drained, and the reaction flask is transferred to a glove box and washed with solvent. The solution is then centrifuged and concentrated to obtain an orange solid, namely, the tridentate pincer manganese complex having the structure shown in Formula I. The preparation reaction process is as follows:

[0077]

[0078] Another aspect of the embodiments of the present invention further provides a tridentate pincer manganese complex prepared by the preparation method.

[0079] In summary, the tridentate pincer manganese complex prepared by the present invention has a novel skeleton structure and exhibits excellent catalytic activity in the dehydrogenation reaction of alcohols. The preparation method is mild, simple to operate, and easy to industrialize, thus having high practical significance.

[0080] Another aspect of the embodiments of the present invention further provides the use of the aforementioned tridentate pincer manganese complex as a metal catalyst in the dehydrogenation of alcohols.

[0081] Correspondingly, another aspect of an embodiment of the present invention further provides a catalyst for alcohol dehydrogenation olefination reaction, comprising the aforementioned tridentate pincer manganese complex.

[0082] Furthermore, another aspect of an embodiment of the present invention provides a method for preparing olefins by dehydrogenating an alcohol compound, which comprises: heating an alcohol compound, a sulfone compound, a catalyst and an alkaline substance to reflux in a fifth solvent to prepare an olefin compound; wherein the catalyst comprises the aforementioned catalyst for alcohol dehydrogenation olefination reaction or the aforementioned tridentate pincer manganese complex.

[0083] Wherein, the structural formula of the alcohol compound is The structural formula of sulfone compounds is The structural formula of olefin compounds is

[0084] R 3 is an aryl group, R 1 Selected from C1-C 20 Any one of alkyl, aryl and hydrogen, R 2 Any one selected from alkyl, aryl, etc.

[0085] Furthermore, the tridentate pincer manganese complex can efficiently catalyze the alcohol dehydrogenation reaction shown in the following formula:

[0086]

[0087] Furthermore, the molar ratio of the alcohol compound, the sulfone compound, the catalyst and the alkaline substance is 1:1:0.3:0.5 to 1:2:0.002:2.

[0088] Furthermore, the fifth solvent includes any one or a combination of two or more of benzene, toluene, xylene, tetrahydrofuran, methyl tert-butyl ether, 1,4-dioxane, ethylene glycol dimethyl ether, n-hexane, etc., but is not limited thereto.

[0089] Furthermore, the alkaline substance includes any one or a combination of two or more of lithium tert-butoxide, potassium tert-butoxide, potassium methoxide, potassium hydroxide, sodium hydroxide, sodium tert-butoxide, sodium carbonate, sodium ethoxide, sodium methoxide, potassium phosphate, potassium hydride, etc., but is not limited thereto.

[0090] Furthermore, the heating temperature is 80 to 150° C., and the reaction time is 12 to 40 hours.

[0091] In some more preferred embodiments, the method for preparing olefins by dehydrogenating an alcohol compound comprises the following steps: under inert gas protection, adding a tridentate manganese complex as a catalyst, a basic substance, and a fifth solvent to a Schlenk flask for reaction; then adding an alcohol compound and a sulfone compound; and heating the mixture to 80-150° C. in an open system for reaction for 12-40 hours. After the reaction, the mixture is concentrated and purified by column chromatography to obtain the target product.

[0092] It has been verified that the catalyst formed by the tridentate pincer manganese complex of the present invention has high reaction activity in the dehydrogenation olefination reaction of alcohol compounds.

[0093] The technical solution of the present invention is further explained below in conjunction with several preferred embodiments. It is easy for those skilled in the art to understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0094] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0095] Example 1

[0096] Synthesis of tridentate pincer manganese complexes

[0097]

[0098] The specific steps are as follows:

[0099] Under nitrogen, 8-aminoquinaldine (1.58 g, 10 mmol), benzyl chloride (1.26 mL, 11 mmol), potassium carbonate (2.07 g, 15 mmol), and 20 mL of isopropanol were added to a reaction flask, heated to 60°C in an oil bath, and allowed to react for 72 h. After the reaction, the mixture was cooled to room temperature, filtered, and concentrated in vacuo. The crude product was thoroughly washed with n-hexane and recrystallized. Drying under vacuum afforded pale yellow crystals S-1 (1.17 g, 47% yield). S-1 was prepared multiple times for subsequent use.

[0100] Under nitrogen, S-1 (1.49 g, 6 mmol) was dissolved in degassed THF (10 mL) and slowly added to the reaction flask. The mixture was cooled to -78°C, and n-butyllithium (5.5 mL, 13.2 mmol) was slowly added. The mixture was then heated to room temperature and stirred for 1 hour. The temperature was then lowered to -78°C, and a solution of diisopropylphosphine chloride (1.1 g, 7.2 mmol) in THF (10 mL) was added. The mixture was then warmed to room temperature and allowed to react for 36 hours. The reaction system was then cooled to 0°C, and a solution of BH3·THF (1 M, 9 mmol) was slowly added dropwise. The reaction was then allowed to react at room temperature for 12 hours. After the reaction, the excess borane was quenched with 1.5 mL of H2O, concentrated, and the crude product was purified by silica gel column chromatography to yield S-2 (1.38 g, 61% yield) as a yellow solid.

[0101] Under nitrogen, S-2 (189.2 mg, 0.5 mmol), DABCO (112.2 mg, 1 mmol), and toluene (4 mL) were added to a reaction flask and heated to 70°C for 12 hours. The mixture was then concentrated, added with n-hexane, filtered through celite, concentrated, and used directly in the next step. The concentrate from the previous step was dissolved in THF (4 mL) and transferred to a reaction flask. The manganese metal catalyst precursor, Mn(CO)5Br (90.7 mg, 0.33 mmol), was added, and heated to 70°C for 48 hours. After the reaction, the temperature was cooled to room temperature, the solvent was drained, and the reaction flask was transferred to a glove box and washed with n-hexane. The mixture was centrifuged and concentrated to yield an orange solid, I-1 (140.4 mg, 77% yield), a novel tridentate pincer manganese complex.

[0102] The inventors of this case also conducted NMR characterization on the orange solid powder, and the data were: 31 P NMR (162 MHz, CDCl3) δ 110.75. 1 H NMR(600MHz, CDCl3)δ8.09(s,1H),7.51(dd,J=116.2,56.0Hz,9H),5.72(s,1H),5.06(s,1H),4 .73(s,1H),3.74(d,J=44.3Hz,2H),2.89(s,1H),2.38(s,1H),1.26(dd,J=149.3,85.5Hz,12H). 13C NMR (151MHz, CDCl3) δ146.35,138.10,136.04,129.06,127.83,127.37,127.12,126.27,125.55,124.5 4,120.71,60.17,41.48(d,J=15.3Hz),29.56(d,J=18.8Hz),25.43,25.28,19.81,19.16,18.50,18.36.

[0103] HR-MS(ESI-TOF):calcd for C 25 H 29 MnN2O2P,[M-Br] + 475.1347, found 475.1320.

[0104] IR(KBr,plates,cm -1 ):1836cm -1 (νCO),1918cm -1 (νCO)in 1:1ratio.

[0105] Example 2

[0106]

[0107]

[0108] Under nitrogen, 8-aminoquinaldine (100 mmol), benzyl bromide (500 mmol), potassium carbonate (1000 mmol), and 500 mL of acetone were added to a reaction flask. The temperature was raised to 45°C in an oil bath and the reaction was continued for 12 hours. After the reaction, the mixture was cooled to room temperature, filtered, and concentrated in vacuo. The crude product was thoroughly washed with n-hexane and recrystallized. Drying under vacuum afforded pale yellow crystals of S-1.

[0109] Under nitrogen protection, S-1 (4 mmol) was dissolved in degassed THF (5 mL) and slowly added to the reaction flask. The temperature was cooled to -78 ° C, and n-butyl lithium (2 mmol) was slowly added. After stirring at room temperature for 1 hour, the temperature was again lowered to -78 ° C, and a solution of diisopropylphosphine chloride (2 mmol) in THF (5 mL) was added. The temperature was then raised to 25 ° C and the reaction was allowed to proceed for 48 hours. The reaction system was then cooled to 0 ° C, and BH3·THF (1 M, 4 mmol) solution was slowly added dropwise. The temperature was raised to room temperature and the reaction was allowed to proceed for 2 hours. After the reaction, the excess borane was quenched with 1.0 ml of H2O, concentrated, and the crude product was purified by silica gel column chromatography to obtain S-2 as a yellow solid.

[0110] Under nitrogen protection, S-2 (0.3 mmol), diethylamine (6 mmol) and toluene (4 mL) were added to a reaction flask and heated to 30 ° C for 24 hours. After concentration, n-hexane was added, filtered through diatomaceous earth and concentrated before being used directly in the next reaction. The concentrate from the previous step was dissolved in toluene (4 mL) and transferred to a reaction flask, and the metal manganese catalyst precursor Mn (CO) 5 Br (0.6 mmol) was added and heated to 130 ° C for 12 hours. After the reaction was completed, the temperature was cooled to room temperature, the solvent was drained, the reaction flask was transferred to a glove box and washed with n-hexane, centrifuged and concentrated to obtain an orange solid I-1.

[0111] Example 3

[0112] Under nitrogen, 8-aminoquinaldine (100 mmol), benzyl bromide (100 mmol), sodium carbonate (100 mmol), and 200 mL of ethanol were added to a reaction flask. The temperature was raised to 100°C in an oil bath and the reaction was continued for 48 hours. After the reaction, the mixture was cooled to room temperature, filtered, and concentrated in vacuo. The crude product was thoroughly washed with n-hexane and recrystallized. Drying under vacuum afforded pale yellow crystals of S-1.

[0113] Under nitrogen protection, S-1 (1 mmol) was dissolved in degassed THF (6 mL) and slowly added to the reaction flask. The temperature was cooled to -45 ° C, and lithium diisopropylamide (10 mmol) was slowly added. After stirring at room temperature for 2 hours, the temperature was again lowered to -45 ° C, and a solution of diisopropylphosphine chloride (10 mmol) in THF (6 mL) was added. The temperature was then raised to 80 ° C and reacted for 12 hours. The reaction system was then cooled to 0 ° C, and BH3·THF (1 M, 10 mmol) solution was slowly added dropwise. The temperature was raised to room temperature and reacted for 12 hours. After the reaction, the excess borane was quenched with 1.5 ml of H2O, concentrated, and the crude product was purified by silica gel column chromatography to obtain a yellow solid S-2.

[0114] Under nitrogen protection, S-2 (1.0 mmol), DABCO (1.0 mmol) and toluene (5 mL) were added to a reaction flask and heated to 150 ° C for 12 hours. After concentration, n-hexane was added, filtered through diatomaceous earth and concentrated before being used directly in the next reaction. The concentrate from the previous step was dissolved in THF (4 mL) and transferred to a reaction flask, and the metal manganese catalyst precursor Mn (CO) 5 Br (0.1 mmol) was added and heated to 30 ° C for 72 hours. After the reaction was completed, the temperature was cooled to room temperature, the solvent was drained, the reaction flask was transferred to a glove box and washed with n-hexane, centrifuged, and concentrated to obtain an orange solid I-1.

[0115] Example 4

[0116] The difference between this embodiment and embodiment 1 is that diphenylphosphine chloride is replaced by di-tert-butylphosphine chloride. The structure of the final product, a tridentate pincer manganese complex, is:

[0117]

[0118] Example 5

[0119] The difference between this embodiment and embodiment 1 is that diphenylphosphine chloride is replaced by dicyclohexylphosphine chloride. The structure of the final product, a tridentate pincer manganese complex, is:

[0120]

[0121] Example 6

[0122] The difference between this embodiment and embodiment 1 is that diphenylphosphine chloride is replaced by diphenylphosphine chloride. The structure of the final product, a tridentate pincer manganese complex, is:

[0123]

[0124] Application Example 1

[0125] The manganese complex obtained in Example 1 was used as a catalyst to carry out a dehydrogenation alkenylation reaction on alcohol compounds:

[0126] Under argon, the manganese complex I-1 obtained in Example 1 was added to a reaction flask as a catalyst (0.005 mmol), a base (0.23 mmol), and toluene (1 mL). Benzyl alcohol (0.2 mmol) and dibenzyl sulfone (0.21 mmol) were then added and heated to 120°C for 19 hours. After the reaction, the temperature was lowered and GC analysis using dodecane as the internal standard was performed. The results are shown in Table 1.

[0127] Table 1 Results of alcohol dehydrogenation to olefins at different alkali amounts a

[0128]

[0129]

[0130] [a] Reaction conditions: benzyl alcohol (0.2 mmol), dibenzyl sulfone (0.21 mmol), base (0.23 mmol), manganese complex I-1 (0.005 mmol), 120°C, 19 h; [b] Conversion and yield were measured by GC using dodecane as the internal standard.

[0131] Application Example 2

[0132] Under argon, the manganese complex I-1 obtained in Example 1 was added to a reaction flask as a catalyst (0.005 mmol), potassium tert-butoxide (0.23 mmol), and a solvent (1 mL). Benzyl alcohol (0.2 mmol) and dibenzyl sulfone (0.21 mmol) were then added and heated to 120°C for 19 hours. After the reaction, the temperature was lowered and GC analysis using dodecane as the internal standard was performed. The results are shown in Table 2.

[0133] Table 2 Results of alcohol dehydrogenation to olefins under different solvents a

[0134]

[0135]

[0136]

[0137] [a] Reaction conditions: benzyl alcohol (0.2 mmol), dibenzyl sulfone (0.21 mmol), potassium tert-butoxide (0.23 mmol), manganese complex I-1 (0.005 mmol), 120°C, 19 h; [b] Conversion and yield were measured by GC using dodecane as the internal standard.

[0138] Application Example 3

[0139] Under argon, the manganese complex I-1 obtained in Example 1 was added as a catalyst, along with potassium tert-butoxide (0.58 mmol) and 1,4-dioxane (2 mL) to a reaction flask. Benzyl alcohol (0.5 mmol) and dibenzyl sulfone (0.53 mmol) were then added and heated to 120°C for 19 hours. After the reaction, the temperature was lowered and GC analysis using dodecane as the internal standard was performed. The results are shown in Table 3.

[0140] Table 3 Results of alcohol dehydrogenation to olefins at different manganese loadings a

[0141]

[0142]

[0143] [a] Reaction conditions: benzyl alcohol (0.5 mmol), dibenzyl sulfone (0.53 mmol), potassium tert-butoxide (0.58 mmol), manganese complex I-1 (x mol%), 120°C, 19 h; [b] Conversion and yield were measured by GC using dodecane as the internal standard; [c] Benzyl alcohol (0.2 mmol), dibenzyl sulfone (0.21 mmol), potassium tert-butoxide (0.23 mmol).

[0144] Application Example 4

[0145]

[0146] Under argon, the manganese complex I-1 obtained in Example 1 was added as a catalyst (0.01 mmol), potassium tert-butoxide (1.15 mmol), and 1,4-dioxane (1 mL) to a reaction flask. Benzyl alcohol (1.0 mmol) and dibenzyl sulfone (1.05 mmol) were then added and heated to 120°C for 40 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to yield the desired product 3a in 68% yield.

[0147] Application Example 5

[0148] Under argon, the manganese complex obtained in Example 2 (catalyst) (0.002 mmol), potassium tert-butoxide (2 mmol), and toluene (1 mL) were added to a reaction flask. After reaction, benzyl alcohol (1.0 mmol) and dibenzyl sulfone (2.0 mmol) were added, and the mixture was heated to 150°C for 12 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to obtain the desired product 3a.

[0149] Application Example 6

[0150] Under argon, the manganese complex obtained in Example 3 was added as a catalyst (0.3 mmol), potassium methoxide (0.5 mmol), and 1,4-dioxane (1 mL) to a reaction flask. Benzyl alcohol (1.0 mmol) and dibenzyl sulfone (1.0 mmol) were then added to the reaction flask. The mixture was heated to 80°C and reacted for 19 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to obtain the desired product 3a.

[0151] Application Example 7

[0152]

[0153] Under argon, the manganese complex obtained in Example 1 was added as a catalyst (0.01 mmol), potassium tert-butoxide (1.15 mmol), and 1,4-dioxane (1 mL) to a reaction flask. p-Methoxybenzyl alcohol (1.0 mmol) and dibenzyl sulfone (1.05 mmol) were then added and heated to 120°C for 40 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to obtain the desired product 3b in a 74% yield.

[0154] Application Example 8

[0155]

[0156] Under argon, the manganese complex obtained in Example 1 was added as a catalyst (0.01 mmol), potassium tert-butoxide (1.15 mmol), and 1,4-dioxane (1 mL) to a reaction flask. After reaction, 3,4,5-trimethoxybenzyl alcohol (1.0 mmol) and benzylphenyl sulfone (1.05 mmol) were added and heated to 120°C for 40 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to obtain the desired product 3c in a 75% yield.

[0157] Application Example 9

[0158]

[0159] Under argon, the manganese complex obtained in Example 1 was added as a catalyst (0.01 mmol), potassium tert-butoxide (1.15 mmol), and 1,4-dioxane (1 mL) to a reaction flask. After reaction, 3-methylbenzyl alcohol (1.0 mmol) and benzylphenyl sulfone (1.05 mmol) were added and heated to 120°C for 40 hours. After completion of the reaction, the mixture was concentrated and purified by column chromatography to obtain the desired product 3d in a 69% yield.

[0160] Application Example 10

[0161] Under argon, the manganese complex obtained in Example 1 was added as a catalyst (0.01 mmol), potassium tert-butoxide (1.15 mmol), and 1,4-dioxane (1 mL) to a reaction flask for reaction. Substituted benzyl alcohol (1.0 mmol) and benzylphenyl sulfone (1.05 mmol) were then added and heated to 120°C for 40 hours. After the reaction, the mixture was concentrated and column chromatography was performed to obtain the corresponding substituted olefin product. The isolated yields are shown in Table 4.

[0162] Table 4 Preparation of polysubstituted olefins by dehydrogenation of aromatic alcohols and sulfones under manganese catalysis a

[0163]

[0164] [a] Reaction conditions: benzyl alcohol (1.0 mmol), benzylphenyl sulfone (1.05 mmol), potassium tert-butoxide (1.15 mmol), manganese complex I-1 (0.01 mol), 1,4-dioxane (1 mL), 120°C, 40 h; isolated yield.

[0165] Through the above embodiments and application examples, it can be found that the tridentate pincer manganese complex prepared by the present invention has a novel structure and high catalytic activity, can achieve efficient dehydrogenation of alcohols to synthesize olefins, and has high application value.

[0166] In addition, the inventors of this case also conducted experiments with other conditions listed in this specification in accordance with the aforementioned embodiments and application examples, and also achieved the same technical effects.

[0167] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A tridentate pincer manganese complex characterized by: The tridentate pincer manganese complex has a structure as shown in formula (I): Wherein, R is selected from isopropyl, tert-butyl, cyclohexyl or phenyl.

2. A method for preparing a tridentate pincer manganese complex, characterized in that: include: preparing a tridentate pincer ligand having a structure as shown in formula (II); reacting the tridentate pincer ligand with a metal manganese catalyst precursor to obtain a tridentate pincer manganese complex; Wherein, R is selected from isopropyl, tert-butyl, cyclohexyl or phenyl, and the metal manganese catalyst precursor includes Mn(CO)5Br.

3. The preparation method according to claim 2, wherein: In a protective atmosphere, heating a mixed reaction system comprising 8-aminoquinaldine, a benzyl compound, a first base, and a first solvent to 45-100° C. and reacting for 12-72 hours to obtain a substituted 8-aminoquinaldine; The substituted 8-aminoquinaldine is mixed with a second solvent, and the temperature is lowered to -78 to -45°C. A second base is added, and the mixture is stirred for 1 to 2 hours. A phosphine chloride reagent is then added, and the mixture is heated to 25 to 80°C and reacted for 12 to 48 hours. After the reaction is completed, a BH3·THF solution is added, and the mixture is stirred for 2 to 12 hours. After post-treatment, a compound having a structure shown in formula (III) is obtained. Under nitrogen protection, a compound having a structure as shown in formula (III), an amine and a third solvent are mixed and heated to 30-150° C. for reaction for 12-24 hours to obtain a tridentate pincer ligand having a structure as shown in formula (II); Wherein, the benzyl compound includes any one of benzyl chloride and benzyl bromide or a combination of the two; The structure of the substituted 8-aminoquinaldine is shown in formula (IV): The structural formula of the phosphine chloride reagent is RRPCl, wherein R is selected from isopropyl, tert-butyl, cyclohexyl or phenyl.

4. The preparation method according to claim 3, wherein: The molar ratio of the 8-aminoquinaldine, the benzyl compound and the first base is 1:1:1 to 1:5:

10.

5. The preparation method according to claim 3, wherein: The molar ratio of the substituted 8-aminoquinaldine to the second base is 1:0.5 to 1:

10.

6. The preparation method according to claim 3, wherein: The molar ratio of the substituted 8-aminoquinaldine to the phosphine chloride reagent is 1:0.5 to 1:

10.

7. The preparation method according to claim 3, wherein: The first base includes any one or a combination of two or more of sodium hydroxide, sodium tert-butoxide, potassium tert-butoxide, potassium methoxide, sodium methoxide, potassium ethoxide, sodium ethoxide, sodium carbonate, potassium hydroxide, potassium carbonate, sodium hydride, potassium hydride and potassium phosphate.

8. The preparation method according to claim 3, wherein: The first solvent includes any one or a combination of two or more of N,N-dimethylformamide, ether, dichloromethane, methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, acetone, tetrahydrofuran and toluene.

9. The preparation method according to claim 3, wherein: The second base includes any one of n-butyllithium, tert-butyllithium, sec-butyllithium, lithium diisopropylamide, sodium bis(trimethylsilyl)amide, lithium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, potassium tert-butoxide, sodium tert-butoxide, sodium hydride, and potassium hydride, or a combination of two or more thereof.

10. The preparation method according to claim 3, characterized in that: The second solvent includes any one or a combination of two or more of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, toluene, n-hexane and 1,4-dioxane.

11. The preparation method according to claim 3, characterized in that: The molar ratio of the compound having the structure shown in formula (III) to the amine is 1:1 to 1:

20.

12. The preparation method according to claim 3, characterized in that: The amine includes any one of diethylamine, triethylamine, DABCO, aniline, and benzylamine, or a combination of two or more thereof.

13. The preparation method according to claim 3, characterized in that: The third solvent includes any one or a combination of two or more of diethyl ether, tetrahydrofuran, methyl tert-butyl ether, toluene, xylene, n-hexane and 1,4-dioxane.

14. The preparation method according to claim 2, characterized in that include: The tridentate pincer ligand and the metal manganese catalyst precursor are mixed in a fourth solvent and heated for reaction to prepare a tridentate pincer manganese complex.

15. The preparation method according to claim 14, characterized in that: The molar ratio of the tridentate pincer ligand to the metal manganese catalyst precursor is 1:2 to 10:

1.

16. The preparation method according to claim 15, characterized in that: The molar ratio of the tridentate pincer ligand to the metal manganese catalyst precursor is 1:1 to 3:

1.

17. The preparation method according to claim 14, characterized in that: The fourth solvent includes any one or a combination of two or more of methanol, ethanol, tetrahydrofuran, toluene, benzene, dichloromethane, ether, n-hexane and 1,4-dioxane.

18. The preparation method according to claim 14, characterized in that: The heating temperature is 30-130° C., and the reaction time is 12-72 hours.

19. The preparation method according to claim 18, characterized in that: The heating temperature is 50-90°C.

20. A tridentate pincer manganese complex prepared by the preparation method according to any one of claims 2 to 19.

21. Use of the tridentate pincer manganese complex according to claim 1 or 20 as a metal catalyst in an alcohol dehydrogenation olefination reaction, wherein the raw materials for the alcohol dehydrogenation olefination reaction are an alcohol compound and a sulfone compound, and the product is an olefin compound; The structural formula of the alcohol compound is The structural formula of sulfone compounds is The structural formula of olefin compounds is in, R 3 is an aryl group, R 1 Selected from C1-C 20 Any one of alkyl, aryl and hydrogen, R 2 Any one selected from alkyl and aryl groups.

22. A catalyst for alcohol dehydrogenation olefination reaction, characterized in that: The invention comprises the tridentate pincer manganese complex according to claim 1 or 20; the raw materials of the alcohol dehydrogenation olefination reaction are alcohol compounds and sulfone compounds, and the product is an olefin compound; The structural formula of the alcohol compound is The structural formula of sulfone compounds is Olefins The structural formula of the compound is Among them, R 3 is an aryl group, R 1 Selected from C1-C 20 Any one of alkyl, aryl and hydrogen, R 2 Any one selected from alkyl and aryl groups.

23. A method for preparing olefins by dehydrogenating alcohol compounds, characterized in that: include: heating an alcohol compound, a sulfone compound, a catalyst, and an alkaline substance under reflux in a fifth solvent to prepare an olefin compound; wherein the catalyst comprises the catalyst according to claim 22 or the tridentate pincer manganese complex according to claim 1 or 20; The structural formula of the alcohol compound is The structural formula of sulfone compounds is The structural formula of olefin compounds is Among them, R 3 is an aryl group, R 1 Selected from C1-C 20 Any one of alkyl, aryl and hydrogen, R 2 Any one selected from alkyl and aryl groups.

24. The method according to claim 23, wherein: The molar ratio of the alcohol compound, the sulfone compound, the catalyst and the alkaline substance is 1:1:0.3:0.5 to 1:2:0.002:

2.

25. The method according to claim 23, wherein: The fifth solvent includes any one or a combination of two or more of benzene, toluene, xylene, tetrahydrofuran, methyl tert-butyl ether, 1,4-dioxane, ethylene glycol dimethyl ether, and n-hexane.

26. The method according to claim 23, wherein: The alkaline substance includes any one or a combination of two or more of lithium tert-butoxide, potassium tert-butoxide, potassium methoxide, potassium hydroxide, sodium hydroxide, sodium tert-butoxide, sodium carbonate, sodium ethoxide, sodium methoxide, potassium phosphate, and potassium hydride.

27. The method according to claim 23, wherein: The heating temperature is 80-150° C. and the heating time is 12-40 hours.

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