Tridentate pincerlike ligand, manganese complex and preparation method and application of tridentate pincerlike ligand and manganese complex

Abstract

The invention discloses a tridentate pincerlike ligand, a manganese complex and a preparation method and application of the tridentate pincerlike ligand and the manganese complex. The tridentate pincerlike ligand has a structure shown as the following: # imgabs0 #; the tridentate pincerlike manganese complex has a structure shown as the following: # imgabs1 # R1 is selected from C1-C20 alkyl or aryl, and R2, R3 and R4 are selected from H, C1-C20 alkyl or aryl and the like. The preparation method of the tridentate pincerlike ligand and the tridentate pincerlike manganese complex comprises the following steps: synthesizing the tridentate pincerlike ligand by using 8-fluoroquinaldine as a raw material, and reacting the tridentate pincerlike ligand with a metal manganese catalyst precursor, thereby efficiently preparing the novel tridentate pincerlike manganese complex. The tridentate pincer-like ligand and the manganese complex prepared by the invention have brand new structures, the preparation method is simple in condition, the catalytic reaction activity is high, and the tridentate pincer-like ligand and the manganese complex have wide application prospects, for example, a glycol compound is prepared by efficient hydrogenation reaction of waste polyester.

Description

Technical Field

[0001] The present invention relates to a tridentate pincer ligand and a manganese complex, and particularly to a novel tridentate pincer ligand, a tridentate pincer manganese complex and a preparation method thereof, as well as an application thereof in the reaction of preparing diols by hydrogenation of polyesters, belonging to the technical field of organic chemical synthesis. Background Art

[0002] For homogeneous catalytic systems, considering that the ligand itself is the core factor for regulating the catalytic activity and reaction selectivity of the catalyst, it is therefore necessary to rationally design and synthesize ligands with different skeletons, coordinate them with suitable metals, and then regulate the electronic effect and spatial three-dimensional structure of the ligand skeleton to achieve the effect of endowing the metal complex catalyst with high activity. In terms of specific ligand types, pincer ligands with multidentate coordination characteristics are a new type of ligand. Compared with the complexes formed by traditional mono- and bidentate ligands, due to the stronger chelate ring effect of pincer ligands, the metal complexes composed of such ligands generally have better stability. Due to the characteristics of some pincer ligand skeletons themselves, pincer ligands generate a second site participating in the catalytic reaction process outside the metal atom by means of donating / accepting hydrogen atoms and hydrogen bond interactions to activate the substrate, thereby changing the reaction path, reducing the reaction energy barrier and enhancing the reaction selectivity. These characteristics make the metal complexes composed of pincer ligands exhibit excellent reaction activity and selectivity in various metal-catalyzed reactions (especially hydrogenation / dehydrogenation reactions). At present, pincer ligands mainly consist of nitrogen-containing heterocycles (such as pyridine, bipyridine, acridine, N-heterocyclic carbene, etc.) or flexible chain structures containing heteroatoms. Considering that the catalytic activity of transition metal complexes composed of existing pincer ligands for polyester degradation reactions is not high, designing and developing new pincer ligand skeletons not only helps to further expand the types of pincer ligands, but also contributes to improving the catalyst performance. On the other hand, manganese, as the third most abundant transition metal element in the earth's crust, has significant advantages such as being cheap and easily available, low toxicity, and environmentally friendly compared with precious metals. Compared with the pincer catalysts of platinum group precious metals with an earlier research start, the development of pincer manganese complexes lags behind. Although significant progress has been made in catalytic hydrogenation / dehydrogenation reactions by pincer manganese catalysts since 2016, due to the relatively low activity of existing manganese complex catalysts, their efficient application in many fields (such as high-value conversion of polyesters) still needs to be explored. Therefore, it is urgent to design and synthesize pincer manganese catalysts with new ligand skeletons, which has important research value for expanding the types and applications of pincer manganese catalysts. Summary of the Invention

[0003] The main object of the present invention is to provide a tridentate pincer ligand and a preparation method thereof to overcome the deficiencies of the prior art.

[0004] Another object of the present invention is to provide a tridentate pincer manganese complex and a preparation method thereof.

[0005] Another object of the present invention is to provide the application of the toothed pincer manganese complex in the preparation of diols by polyester hydrogenation reaction.

[0006] To achieve the foregoing invention objects, the technical solutions adopted by the present invention include:

[0007] An embodiment of the present invention provides a tridentate pincer ligand having a structure shown in formula (I):

[0008]

[0009] Wherein, R 1 is selected from C1-C 20 alkyl or aryl, R 2 , R 3 and R 4 are each independently selected from H or any one or more combinations of C1-C 20 alkyl or aryl.

[0010] An embodiment of the present invention also provides a preparation method of a tridentate pincer ligand, which includes:

[0011] In a protective atmosphere, 8-fluoroquinoline and selenium dioxide are reacted to obtain a substituted 8-fluoroquinoline-2-carbaldehyde;

[0012] The substituted 8-fluoroquinoline-2-carbaldehyde is mixed with a primary amine R 3 NH2, a reducing agent is added, the reaction is then quenched, and Boc2O is added for reaction to obtain a product shown in formula (III);

[0013] The phosphine lithium reagent R 1 R 1 PLi is reacted with the product shown in formula (III) to obtain a product shown in formula (IV); then acid treatment is carried out to obtain a tridentate pincer ligand shown in formula (V);

[0014] Alternatively, the substituted 8-fluoroquinoline-2-carbaldehyde is reacted with a Grignard reagent R 2 MgBr to obtain an alcohol shown in formula (VI), and then reacted with a first base to obtain a chlorine-containing compound shown in formula (VII);

[0015] The chlorine-containing compound shown in formula (VII) is reacted with an amination reagent R 3 R 4 NH, a second base, and an iodine-containing additive to obtain a product shown in formula (VIII);

[0016] The phosphine lithium reagent R 1 R1 PLi reacts with the product shown in formula (VIII) to obtain a tridentate pincer ligand shown in formula (I);

[0017] Among them, the substituted 8-fluoroquinoline-2-carbaldehyde has a structure shown in formula (II):

[0018]

[0019] Among them, R 1 is selected from alkyl or aryl groups of C1-C 20 , R 2 , R 3 and R 4 are each independently selected from any one or a combination of more than one of H or alkyl or aryl groups of C1-C 20 .

[0020] An embodiment of the present invention also provides a tridentate pincer manganese complex, which has a structure shown in formula (IX):

[0021]

[0022] Among them, R 1 is selected from alkyl or aryl groups of C1-C 20 , R 2 , R 3 and R 4 are each independently selected from any one or a combination of more than one of H, alkyl or aryl groups of C1-C 20 .

[0023] An embodiment of the present invention also provides a preparation method of a tridentate pincer manganese complex, which includes:

[0024] Preparing a tridentate pincer ligand having a structure shown in formula (I) according to the foregoing preparation method;

[0025] Reacting the tridentate pincer ligand with a metal manganese catalyst precursor to obtain a tridentate pincer manganese complex;

[0026] The metal manganese catalyst precursor includes Mn(CO)5Br.

[0027] An embodiment of the present invention also provides the application of the tridentate pincer manganese complex as a metal catalyst in the preparation of diols by hydrogenation of polyesters.

[0028] Correspondingly, an embodiment of the present invention also provides a pincer manganese catalyst, which includes the foregoing tridentate pincer manganese complex.

[0029] Furthermore, an embodiment of the present invention also provides a method for preparing diols by hydrogenation reaction of polyester, which comprises: heating polyester, catalyst and alkaline substance in a seventh solvent to react to obtain diol compounds; wherein the catalyst is the aforementioned pincer manganese catalyst.

[0030] Furthermore, the structural formula of the polyester is The structural formula of the diol compound is The R 5 and R 6 Including C1-C 20 Any one of an alkyl group or an aryl group.

[0031] Compared with the prior art, the present invention has at least the following advantages:

[0032] 1) The preparation method of the novel tridentate pincer ligand and tridentate pincer manganese complex provided by the present invention has cheap and readily available starting materials, a simple reaction route, mild conditions and high yield;

[0033] 2) The tridentate pincer ligand and its manganese complex synthesized in the present invention have novel structures and a brand-new skeleton structure. They are the first to create a PNN-type tridentate pincer skeleton and a corresponding manganese catalyst based on a quinoline skeleton. 3 Site, N atom connected to Csp 2 sites, forming a unique spatial and electronic effect distribution, significantly improving the selectivity of metal catalysts, with high reaction activity, and can achieve efficient hydrogenation of polyesters, with good application prospects;

[0034] 3) The pincer manganese catalyst provided by the present invention has a high reactivity (TON can reach up to 5300) in the polyester hydrogenation reaction to prepare alcohol. DETAILED DESCRIPTION

[0035] In view of the defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution mainly uses 8-fluoroquinaldine as a raw material to first synthesize a series of tridentate pincer ligands with a new skeleton, and then reacts them with a metal manganese precursor to prepare a series of new tridentate pincer manganese complexes. The technical solution, its implementation process and principle will be further explained as follows.

[0036] Specifically, as one aspect of the technical solution of the present invention, a novel tridentate pincer ligand involved therein has a structure as shown in formula (I):

[0037]

[0038] Among them, R 1 Selected from C1~C 20 An alkyl or aryl group, R2 , R 3 and R 4 is selected from any one or a combination of more than one of H or an alkyl or aryl group having 1 to C 20 .

[0039] As another aspect of the technical solution of the present invention, a preparation method of a novel tridentate pincer ligand mainly includes: in a protective atmosphere, using 8-fluoroquinaldine as a starting material, a series of tridentate pincer ligands with a new PNN-type quinaldine skeleton are efficiently synthesized through 4 to 6 steps.

[0040] The ligand structure provided by the present invention is a novel PNN-type tridentate pincer skeleton based on a quinoline skeleton and a corresponding manganese catalyst. The P atom in the quinoline skeleton is connected to the Csp 3 site, and the N atom is connected to the Csp 2 site, forming a unique spatial and electronic effect distribution, significantly improving the selectivity of the metal catalyst.

[0041] In some embodiments, a preparation method of a novel tridentate pincer ligand includes:

[0042] In a protective atmosphere, 8-fluoroquinaldine and selenium dioxide are reacted to obtain substituted 8-fluoroquinoline-2-carbaldehyde;

[0043] The substituted 8-fluoroquinoline-2-carbaldehyde is mixed with a primary amine R 3 NH2, a reducing agent is added, the reaction is then quenched, and Boc2O is added for reaction to obtain a product as shown in formula (III);

[0044] A phosphine lithium reagent R 1 R 1 PLi is reacted with the product shown in formula (III) to obtain a product as shown in formula (IV); then acid treatment is carried out to obtain a tridentate pincer ligand as shown in formula (V).

[0045] Among them, the substituted 8-fluoroquinoline-2-carbaldehyde has a structure as shown in formula (Ⅱ):

[0046]

[0047] R 1 is selected from an alkyl or aryl group having 1 to C 20 , and R 3 is selected from any one or a combination of more than one of H or an alkyl or aryl group having 1 to C 20 .

[0048] As another aspect of the technical solution of the present invention, a preparation method of a tridentate pincer ligand includes:

[0049] In a protective atmosphere, 8-fluoroquinaldine and selenium dioxide are reacted to obtain a substituted 8-fluoroquinoline-2-carbaldehyde;

[0050] The substituted 8-fluoroquinoline-2-carbaldehyde is reacted with a Grignard reagent R 2 MgBr to obtain an alcohol as shown in formula (VI), and then reacted with a first base to obtain a chlorine-containing compound as shown in formula (VII);

[0051] The chlorine-containing compound as shown in formula (VII) is reacted with an amination reagent R 3 R 4 NH, a second base, and an iodine-containing additive to obtain a product as shown in formula (VIII);

[0052] A phosphine lithium reagent R 1 R 1 PLi is reacted with the product as shown in formula (VIII) to prepare a tridentate pincer ligand as shown in formula (I);

[0053] Wherein, the substituted 8-fluoroquinoline-2-carbaldehyde has a structure as shown in formula (II):

[0054]

[0055] Wherein, R 1 is selected from alkyl or aryl groups having 1 to C 20 , and R 2 , R 3 and R 4 are each independently selected from H or alkyl or aryl groups having 1 to C 20 or any combination of one or more of the above.

[0056] In some preferred embodiments, in the above preparation method, the preparation method of the substituted 8-fluoroquinoline-2-carbaldehyde specifically includes: in a protective atmosphere, heating a mixed reaction system containing 8-fluoroquinaldine, selenium dioxide and a first solvent to 50-150 °C and reacting for 1-24 h to obtain the substituted 8-fluoroquinoline-2-carbaldehyde.

[0057] In some preferred embodiments, the molar ratio of 8-fluoroquinaldine to selenium dioxide is 1:0.5 to 1:10.

[0058] Furthermore, the first solvent may include any one or a combination of two or more of N,N-dimethylformamide, dichloromethane, methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, acetone, tetrahydrofuran, and toluene, but is not limited thereto.

[0059] In some preferred embodiments, the preparation method specifically includes: mixing the substituted 8-fluoroquinoline-2-carbaldehyde with a second solvent, adding a primary amine R3 NH2 and stirred at room temperature for 12 - 24 h. After concentrating the solvent, a third solvent and a reducing agent were added, and the reaction was continued with stirring and then quenched. Then Boc2O was added and reacted at 0 - 150 °C for 1 - 24 h to obtain the product shown in formula (III).

[0060] In some preferred embodiments, the molar ratio of the substituted 8 - fluoroquinoline - 2 - carbaldehyde, primary amine, and reducing agent is 1:1:1 - 1:5:10.

[0061] Furthermore, the reducing agent may include any one or a combination of two or more of sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, lithium borohydride, lithium aluminum hydride, sodium thiosulfate, and Red - Al, etc., but is not limited thereto.

[0062] Furthermore, the second solvent may include any one or a combination of two or more of diethyl ether, dichloromethane, N,N - dimethylformamide, methanol, ethanol, isopropanol, acetonitrile, 1,4 - dioxane, tetrahydrofuran, and toluene, etc., but is not limited thereto.

[0063] Furthermore, the third solvent may include any one or a combination of two or more of methanol, ethanol, isopropanol, 1,4 - dioxane, and tetrahydrofuran, etc., but is not limited thereto.

[0064] In some preferred embodiments, the preparation method specifically includes: reacting the lithium phosphine reagent R 1 R 1 PLi with the product shown in formula (III) in a fourth solvent at - 78 - 150 °C for 6 - 48 h to obtain the product shown in formula IV.

[0065] In some preferred embodiments, the molar ratio of the product shown in formula (III) to the lithium phosphine reagent R 1 R 1 PLi is 1:0.5 - 1:10.

[0066] Furthermore, the fourth solvent may include any one or a combination of two or more of diethyl ether, 1,4 - dioxane, tetrahydrofuran, etc., but is not limited thereto.

[0067] In some preferred embodiments, the preparation method specifically includes: subjecting the product shown in formula (IV) to acid treatment with an N - deprotection reagent to prepare the tridentate pincer ligand shown in formula (V).

[0068] In some preferred embodiments, the molar ratio of the product shown in formula (IV), the tridentate pincer ligand shown in formula (V), and the N - deprotection reagent is 1:1:1 - 1:5:10.

[0069] In some preferred embodiments, the preparation method specifically includes: mixing the substituted 8-fluoroquinoline-2-carbaldehyde with a fifth solvent and adding a Grignard reagent R at -78°C to 50°C 2 to react with MgBr to obtain an alcohol as shown in formula (VI).

[0070] In some preferred embodiments, the molar ratio of the substituted 8-fluoroquinoline-2-carbaldehyde to the Grignard reagent is 1:0.5 to 1:10.

[0071] Furthermore, the fifth solvent may include any one or a combination of two or more of diethyl ether, 1,4-dioxane, tetrahydrofuran, etc., but is not limited thereto.

[0072] In some preferred embodiments, the preparation method specifically includes: reacting the alcohol as shown in formula (VI), thionyl chloride and a first base to obtain a chlorine-containing compound as shown in formula (VII), wherein the reaction temperature is 25 to 150°C and the reaction time is 1 to 24 h.

[0073] In some preferred embodiments, the molar ratio of the alcohol as shown in formula (VI), thionyl chloride to the first base is 1:1:0.01 to 1:10:5.

[0074] Furthermore, the first base may include any one or a combination of two or more of triethylamine, triethylenediamine (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 4-dimethylaminopyridine (DMAP), pyridine, potassium tert-butoxide, potassium methoxide, sodium methoxide, potassium ethoxide, sodium ethoxide, etc., but is not limited thereto.

[0075] In some preferred embodiments, the preparation method specifically includes: reacting the chlorine-containing compound as shown in formula (VII), an amination reagent R 3 R 4 NH, a second base, and an iodine-containing additive at 0 to 150°C for 12 to 24 h to obtain a product as shown in formula (VIII).

[0076] In some preferred embodiments, the molar ratio of the chlorine-containing compound as shown in formula (VII), the amination reagent R 3 R 4 NH, the second base to the iodine-containing additive is 1:1:1:0.01: to 1:5:10:5.

[0077] Furthermore, the second base may include 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, etc., but is not limited thereto.

[0078] In some preferred embodiments, the preparation method specifically includes: reacting a lithium phosphine reagent R 1 R 1 PLi with the product shown in formula (VIII) in a fourth solvent at -78 to 150 °C for 6 to 48 h to obtain a tridentate pincer ligand shown in formula (I).

[0079] In some preferred embodiments, the molar ratio of the product shown in formula (VIII) to the lithium phosphine reagent is 1:0.5 to 1:10.

[0080] In some more specific embodiments, the preparation method of the tridentate pincer ligand having the structure shown in formula (V) includes:

[0081] In a protective atmosphere, heating a mixed reaction system containing 8-fluoroquinaldine, selenium dioxide and a first solvent to 50 to 150 °C and reacting for 1 to 24 h to obtain a substituted 8-fluoroquinoline-2-carbaldehyde;

[0082] Mixing the substituted 8-fluoroquinoline-2-carbaldehyde with a second solvent, adding a primary amine R 3 NH2 and stirring at room temperature for 12 to 24 h. After concentrating the solvent, adding a third solvent and a reducing agent, continuing to stir and then quenching the reaction. After post-treatment, a crude secondary amine product is obtained. Adding Boc2O and reacting at 0 to 150 °C for 1 to 24 h, a product shown in formula (III) is obtained. Using an in-situ prepared lithium phosphine reagent R 1 R 1 PLi reacts with the product shown in formula (III) in a fourth solvent at -78 to 150 °C for 6 to 48 h to obtain a product shown in formula (IV). After acid treatment, deprotection gives the novel tridentate pincer ligand shown in formula (V).

[0083]

[0084] Among them, R 1 is selected from an alkyl or aryl group of C1-C 20 , and R 3 is selected from any one or a combination of more than one of H or an alkyl or aryl group of C1-C 20 .

[0085] In some more specific embodiments, the preparation method of the tridentate pincer ligand having the structure shown in formula (I) includes:

[0086] In a protective atmosphere, heating a mixed reaction system containing 8-fluoroquinaldine, selenium dioxide and a first solvent to 50 to 150 °C and reacting for 1 to 24 h to obtain a substituted 8-fluoroquinoline-2-carbaldehyde;

[0087] Mix the 8 - fluoroquinoline - 2 - carbaldehyde with a fifth solvent and add a Grignard reagent R at - 78 °C to 50 °C. 2 MgBr to obtain the corresponding alcohol shown in formula (VI); subsequently, react the alcohol with thionyl chloride and a first base to obtain a chlorine - containing compound shown in formula (VII). React the chlorine - containing compound with an amination reagent R 3 R 4 NH, a second base, and an iodine - containing additive at 0 to 150 °C for 12 to 24 h to obtain a product shown in formula (VIII). React the in - situ prepared lithium phosphine reagent R 1 R 1 PLi with the product shown in formula (VIII) in a fourth solvent at - 78 to 150 °C for 6 to 48 h to obtain a novel tridentate pincer ligand shown in formula (I).

[0088]

[0089] Among them, R 1 is selected from an alkyl or aryl group of C1 - C 20 , and R 2 , R 3 and R 4 are each independently selected from H or any one or more combinations of an alkyl or aryl group of C1 - C 20 .

[0090] Specifically, the synthesis method of the tridentate pincer ligand with the structure shown in formula I or V includes the following steps:

[0091]

[0092] Furthermore, when R 1 is selected from phenyl, R 2 and R 4 are hydrogen, and R 3 is benzyl, the structural formula of the ligand is:

[0093]

[0094] And its NMR and high - resolution characterization data are: 1 HNMR(400MHz,CDCl3)δ8.08(d,J=8.4Hz,1H),7.78(d,J=8.4Hz,1H),7.40–7.19(m,17H),7.10–7.07(m,1H),3.92(s,2H),3.56(s,2H),2.45(br,1H); 1313C NMR (151 MHz, CDCl3) δ 159.1, 148.7 (d, J = 15.9 Hz), 140.3, 138.6 (d, J = 12.1 Hz), 137.7 (d, J = 10.0 Hz), 136.6, 134.4 (d, J = 20.7 Hz), 133.9, 128.7, 128.6 (d, J = 7.2 Hz), 128.4 (d, J = 5.1 Hz), 126.9 (d, J = 2.4 Hz), 126.2, 121.1, 54.1, 53.0; 31 31P NMR (243 MHz, CDCl3) δ -13.2; HRMS (ESI) calcd. for C 29 H 26 N2P [M+H]: 433.1834, found: 433.1819.

[0095] Further, R 1 is selected from phenyl, R 2 and R 4 is hydrogen, R 3 is cyclohexyl, the structural formula of the ligand is:

[0096]

[0097] And its nuclear magnetic and high-resolution characterization data are: 1 1H NMR (400 MHz, CDCl3) δ 8.12 (d, J = 8.0 Hz, 1H), 7.80 (d, J = 8.0 Hz, 1H), 7.41–7.29 (m, 12H), 7.09–7.06 (m, 1H), 4.08 (s, 2H), 2.44–2.39 (m, 1H), 1.76–1.53 (m, 5H), 1.15–0.96 (m, 5H); 13 13C NMR (151 MHz, CDCl3) δ 148.5 (d, J = 15.9 Hz), 138.2 (d, J = 12.4 Hz), 137.5 (d, J = 10.6 Hz), 137.1, 134.4 (d, J = 20.4 Hz), 128.8, 128.6 (d, J = 7.4 Hz), 128.5, 127.0, 126.5, 120.8, 57.0, 51.4, 32.6, 25.9, 25.0; 31 31P NMR (162 MHz, CDCl3) δ -13.7; HRMS (ESI) calcd. for C 28 H 30 N2P [M+H]: 425.2147, found: 425.2139.

[0098] Further, R1 Selected from phenyl, R 2 is methyl, R 3 is cyclohexyl, R 4 When it is hydrogen, the structural formula of the ligand is:

[0099]

[0100] And its NMR characterization data are as follows: 1 H NMR(400MHz,CDCl3)δ8.09(d,J=8.4Hz,1H),7.78(d,J=8.0Hz,1H),7.38–7.30(m,12H),7.08–7.05(m,1H),4.02(q,J=6.8Hz,1H),2.11–2.05(m,1H),1.80–1.76(m,1H),1.62–1.42(m,4H),1.16(d,J=6.4Hz,3H),1.04–0.86(m,5H); 13 C NMR(151MHz,CDCl3)δ148.6,148.4,138.6,138.5,138.0,137.8,137.7,136.4,134.4,134.3,134.2,134.1,133.7,128.4,128.4,128.3,128.2,126.7,125.9,120.1,55.7,54.4,33.9,33.0,26.1,25.2,25.0,23.4; 31 P NMR(162MHz,CDCl3)δ-13.2;HRMS(ESI)calcd.forC 28 H 30 N2P[M+H]:439.2303,found:439.2284.

[0101] In some more preferred specific embodiments, the specific reaction steps of the tridentate pincer ligand having the structure shown in formula (V) are as follows:

[0102] Under nitrogen protection, 8-fluoroquinaldine, selenium dioxide and a first solvent are added into a reaction flask, heated to 50-150 °C and reacted for 1-24 hours, cooled and filtered, and the substituted 8-fluoroquinoline-2-carbaldehyde shown in formula (II) is obtained by column chromatography separation. Subsequently, the substituted 8-fluoroquinoline-2-carbaldehyde, primary amine R 3NH2 and the second solvent are added into a reaction flask, and stirred at room temperature for 12 to 24 hours. After concentrating the solvent, the third solvent and a reducing agent are added, and the reaction is continued to be stirred and then quenched. After post-treatment, a crude product of secondary amine is obtained. Boc2O is added and reacted at 0 to 150 °C for 1 to 24 h, and the product shown in Formula III is obtained. Using the in-situ prepared lithium phosphine reagent R 1 R 1 PLi and the product shown in Formula (III) are reacted in the fourth solvent at -78 to 150 °C for 6 to 48 h to obtain the product shown in Formula (IV). After being treated with trifluoromethanesulfonic acid, deprotection is carried out to obtain the novel tridentate pincer ligand shown in Formula (V).

[0103] In some more preferred specific embodiments, the specific reaction steps of the tridentate pincer ligand having the structure shown in Formula (I) are as follows:

[0104] Under nitrogen protection, 8-fluoroquinaldine, selenium dioxide and the first solvent are added into a reaction flask, heated to 50 to 150 °C and reacted for 1 to 24 hours. After cooling, filtration is carried out, and column chromatography separation is carried out to obtain the substituted 8-fluoroquinoline-2-carbaldehyde shown in Formula (II). Under nitrogen protection, the substituted 8-fluoroquinoline-2-carbaldehyde is mixed with the fifth solvent and the Grignard reagent R 2 MgBr is added at -78 °C to 50 °C to obtain the corresponding alcohol shown in Formula (VI); subsequently, the alcohol is reacted with thionyl chloride and the first base to obtain the chlorine-containing compound shown in Formula (VII). The chlorine-containing compound is reacted with an amination reagent R 3 R 4 NH, the second base, and an iodine-containing additive at 0 to 150 °C for 12 to 24 h to obtain the product shown in Formula (VIII). Using the in-situ prepared lithium phosphine reagent R 1 R 1 PLi and the product shown in Formula (VIII) are reacted in the fourth solvent at -78 to 150 °C for 6 to 48 h to obtain the novel tridentate pincer ligand shown in Formula (I).

[0105] As another aspect of the technical solution of the present invention, it also relates to a tridentate pincer manganese complex having the structure shown in Formula (IX):

[0106]

[0107] Wherein, R 1 is selected from alkyl or aryl groups of C1 to C 20 , and R 2 , R 3 and R 4 are selected from any one or a combination of more than one of H, alkyl or aryl groups of C1 to C 20 .

[0108] As another aspect of the technical solution of the present invention, the preparation method of the tridentate pincer-shaped manganese complex involved therein includes:

[0109] Prepare a tridentate pincer-shaped ligand having the structure shown in formula (I) according to the foregoing preparation method;

[0110]

[0111] React the tridentate pincer-shaped ligand with a metal manganese catalyst precursor to obtain a tridentate pincer-shaped manganese complex shown in formula (IX).

[0112]

[0113] Among them, R 1 is selected from C1-C 20 alkyl or aryl, and R 2 , R 3 and R 4 are selected from any one or a combination of more than one of H or C1-C 20 alkyl or aryl, etc.

[0114] In some preferred embodiments, the metal manganese catalyst precursor includes Mn(CO)5Br.

[0115] In some preferred embodiments, the preparation method specifically includes: mixing the tridentate pincer-shaped ligand and the metal manganese catalyst precursor in a sixth solvent, and heating for reaction to obtain a novel tridentate pincer-shaped manganese complex. Specifically, the reaction process is as follows:

[0116]

[0117] In some preferred embodiments, the molar ratio of the tridentate pincer-shaped ligand to the metal manganese catalyst precursor is 1:2 to 10:1, preferably 1:1 to 3:1.

[0118] Furthermore, the sixth solvent may include any one or a combination of two or more of tetrahydrofuran, toluene, benzene, dichloromethane, methanol, ethanol, isopropanol, ether, n-hexane, and 1,4-dioxane, etc., but is not limited thereto.

[0119] In some preferred embodiments, the reaction temperature is 25 to 150 °C, preferably 50 to 110 °C, and the reaction time is 6 to 36 h.

[0120] In some more preferred specific embodiments, the preparation method comprises the following specific reaction steps: under a nitrogen atmosphere, a tridentate pincer ligand as shown in the structural formula (I), a metal manganese catalyst precursor and a sixth solvent are added to a reaction bottle, and the reaction is heated for 6 to 36 hours. After returning to room temperature, concentration, washing, centrifugation, concentration and other steps are performed to obtain the target tridentate pincer manganese complex as shown in the structural formula (IX).

[0121] As a preferred technical solution, the preparation method comprises: adding a tridentate pincer ligand, a metal manganese catalyst precursor Mn(CO)5Br and a sixth solvent into a reaction bottle, and heating to 25-150°C for reaction for 6-36 hours. After the reaction is completed, the temperature is lowered to room temperature, the solvent is drained, the reaction bottle is transferred into a glove box, and the solvent is added for washing, centrifugation, and concentration to obtain an orange-red solid, i.e., a tridentate pincer manganese complex with a structure as shown in (IX).

[0122] In summary, the tridentate pincer manganese complex prepared by the present invention has a new skeleton structure, and has shown excellent catalytic activity in the reaction of preparing glycol compounds by hydrogenation of polyester through preliminary testing. The preparation method has mild conditions, simple operation, and is easy to industrialize. The obtained pincer manganese catalyst will have broad application prospects in the future.

[0123] Another aspect of the embodiments of the present invention further provides a tridentate pincer manganese complex prepared by the aforementioned preparation method.

[0124] 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 reaction of preparing diols by hydrogenation of polyester.

[0125] Correspondingly, another aspect of an embodiment of the present invention further provides a pincer manganese catalyst, which includes the tridentate pincer manganese complex.

[0126] The catalyst provided by the present invention has strong stability. By introducing fully aromatic hydrocarbon substituents to modify the P atom and utilizing the steric hindrance effect and conjugated stabilization of the aromatic ring, the catalyst can still maintain high structural integrity in the presence of air / water, thus solving the technical bottleneck of easy deactivation of high-yield metal catalysts.

[0127] Furthermore, compared with the NNP type manganese catalyst, the PNN type manganese complex of the present invention has the advantages of higher hydrogenation activity, milder reaction conditions, and wider substrate universality.

[0128] As another aspect of the technical solution of the present invention, a method for preparing diols by hydrogenation reaction of polyester involves:

[0129] The polyester, the catalyst and the alkaline substance are heated and reacted in a seventh solvent to obtain a diol compound; wherein the catalyst includes the aforementioned pincer manganese catalyst.

[0130] Furthermore, the structural formula of the waste polyester compound is The structural formula of the diol compound is Said R 5 and R 6 include any one of alkyl or aryl containing C1-C 20 of.

[0131] Furthermore, the pincer manganese catalyst can efficiently catalyze the polyester hydrogenation reaction shown by the following formula:

[0132]

[0133] Furthermore, the molar ratio of the polyester, the catalyst and the basic substance is 1:0.0001:0.0001 to 1:0.05:0.05.

[0134] Furthermore, the seventh solvent may include any one or a combination of two or more of methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, tetrahydrofuran, diethyl ether, n-hexane, ethylene glycol dimethyl ether, cyclohexane, benzene, toluene, xylene, etc., but is not limited thereto.

[0135] Furthermore, the basic substance may include any one or a combination of two or more of potassium tert-butoxide, sodium tert-butoxide, sodium ethoxide, sodium methoxide, sodium hydride, potassium hydride, potassium ethoxide, potassium methoxide, potassium phosphate, bis(trimethylsilyl)amino potassium \ bis(trimethylsilyl)amino sodium, bis(trimethylsilyl)amino lithium, etc., but is not limited thereto.

[0136] Furthermore, the temperature of the reaction is 30-180 °C, preferably 30-120 °C, and the reaction time is 12-60 h.

[0137] In some more preferred specific embodiments, the reaction steps of the method for preparing diol by hydrogenating polyester are specifically as follows: under argon protection, the pincer manganese catalyst, the basic substance and the seventh solvent are added to the reaction flask, and after reaction, the polyester is added, and the mixture is heated to 30-120 °C and reacted for 12-60 hours. After the reaction is completed, it is concentrated, and the target product is obtained after column chromatography.

[0138] It has been verified that the pincer manganese catalyst of the present invention has high reaction activity (TON can reach up to 5300 at most) in the reaction of preparing alcohol compounds by hydrogenating polyester. This is because the unique side-arm N-H group of this type of catalyst and the extended π-conjugated system act synergistically, and the dual metal-ligand cooperation (MLC) more effectively promotes key steps such as H2 activation and hydrogen-bond-assisted hydride transfer, thereby significantly improving the hydrogenation efficiency of the catalyst.

[0139] The technical solution of the present invention will be further explained and illustrated 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 on the present invention. However, those skilled in the art can easily understand that the specific material ratios, process conditions and their results described in the embodiments are only used to illustrate the present invention and should not and will not limit the present invention described in detail in the claims.

[0140] In the following embodiments, the experimental materials used can be obtained from conventional biochemical reagent companies without special instructions.

[0141] Example 1

[0142] Synthesis of tridentate pincer manganese complex [Mn]-1

[0143]

[0144] The specific steps are as follows:

[0145] Under nitrogen protection, 8-fluoroquinoline (5.3 g, 33.0 mmol), selenium dioxide (7.3 g, 66.0 mmol) and 1,4-dioxane (60 mL) were added to the reaction flask, and the temperature was raised to 80 °C for 4 hours. After cooling, filtration was carried out by suction and the solution was concentrated, and column chromatography was carried out to obtain S-2 (4.7 g, yield 81%).

[0146] Under nitrogen protection, S-2 (4.9 g, 28.0 mmol), cyclohexylamine (3.1 g, 30.8 mmol) and toluene (25 mL) were added to the reaction flask, and stirred at room temperature for 12 hours. The crude product obtained after concentrating the solvent was dissolved in methanol (60 mL). NaBH4 (1.3 g, 33.6 mmol) was added in batches and stirred for 4 hours. Subsequently, the reaction was quenched with saturated ammonium chloride solution. After concentrating to remove the solvent, extraction was carried out with ethyl acetate, the organic phases were combined, dried over anhydrous sodium sulfate and concentrated to obtain a crude product. Subsequently, it was dissolved in dichloromethane (30 mL), DMAP (341.6 mg, 2.8 mmol) and Boc2O (9.2 g, 42.0 mmol) were added and reacted at room temperature for 12 hours. Subsequently, the reaction was quenched with saturated ammonium chloride, concentrated and column chromatography was carried out to obtain S-3 (8.6 g, yield 86%).

[0147] Under nitrogen protection, Ph2PH (4.0 g, 21.5 mmol) and tetrahydrofuran (40 mL) were added to a reaction flask. The temperature was lowered to -78 °C, and n-butyllithium (8.6 mL, 21.5 mmol) was added. Subsequently, the mixture was stirred at room temperature for 1 hour, then cooled to -78 °C again, and a THF (10 mL) solution of the above S-3 was added. Then, the temperature was raised to 60 °C and the reaction was carried out for 12 hours. After the reaction was completed, the solvent was concentrated, and column chromatography was performed to obtain a white solid S-4 (8.0 g, yield 71%).

[0148] Under nitrogen protection, S-4 (315 mg, 0.6 mmol) and dichloromethane (5 mL) were added to a reaction flask. Subsequently, trifluoroacetic acid (1 mL) was added, and the reaction was carried out at room temperature for 4 hours. After concentration, the solvent and excess acid were removed, and it was alkalized with NaOH (aq. 2M solution). Then, it was extracted with dichloromethane, the organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was concentrated to remove to obtain the crude product directly used for the next step of the reaction.

[0149] Under nitrogen protection, the crude product from the previous step was dissolved in THF (5 mL) and transferred to a reaction flask. The metal manganese catalyst precursor Mn(CO)5Br (138 g, 0.5 mmol) was added, and the reaction was carried out by heating to 70 °C for 12 hours. After the reaction was completed, the temperature was lowered to room temperature, the solvent was dried under reduced pressure, the reaction flask was transferred into a glove box and washed with ether, centrifuged, and concentrated to obtain an orange-red solid [Mn]-1 (295.3 mg, yield 96%), namely the novel tridentate pincer manganese complex.

[0150] The inventor of this case also characterized the orange-red solid [Mn]-1 by NMR, high-resolution, etc. The data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.26 (s, 1H), 8.13–8.05 (m, 4H), 7.76 (s, 1H), 7.49 (br, 1H), 7.40 (s, 3H), 7.27 (br, 3H), 7.20–7.16 (m, 2H), 4.39 (s, 2H), 4.21 (br, 1H), 2.91–2.86 (m, 1H), 2.26–2.23 (m, 1H), 2.19–2.16 (m, 1H), 1.92–1.80 (m, 4H), 1.72–1.68 (m, 1H), 1.39–1.27 (m, 3H); 1313C NMR(151MHz,CDCl3 / CD3OD)δ231.7,230.4,165.9,161.8,152.4(d,J=22.2Hz),137.6(d,J=27.3Hz),136.9,134.8(d,J=23.6Hz),134.8(d,J=9.8Hz),133.2,132.9,132.5,131.2(d,J=10.3Hz),130.9,130.0(d,J=2.4Hz),129.1,128.6,128.1(d,J=9.1Hz),127.9(d,J=9.7Hz),127.5(d,J=4.8Hz),120.2,119.0,62.8(m),59.4,57.8,32.2(d,J=45.9Hz),25.5(m); 31 31P NMR(162MHz,CDCl3)δ85.5.HRMS(ESI)calcd.forMnC 30 H 29 N2O2P[M-Br]:535.1347,found:535.1337.IR(νCO)=1906.6,1824.4cm -1 。

[0151] Example 2

[0152] The difference between this example and Example 1 is that 8-fluoroquinaldine(33.0 mmol),selenium dioxide(330.0 mmol) and tetrahydrofuran(60 mL) were added to a reaction flask,and the temperature was raised to 50 °C and reacted for 24 hours.After cooling,the mixture was filtered by suction and concentrated,and column chromatography was carried out to obtain S-2(yield 70%).

[0153] Example 3

[0154] The difference between this example and Example 1 is that 8-fluoroquinaldine(33.0 mmol),selenium dioxide(16.5 mmol) and 1,4-dioxane(60 mL) were added to a reaction flask,and the temperature was raised to 150 °C and reacted for 1 hour.After cooling,the mixture was filtered by suction and concentrated,and column chromatography was carried out to obtain S-2(yield 80%).

[0155] Example 4

[0156] This example is different from Example 1 in that: S-2 (28.0 mmol), cyclohexylamine (28 mmol), and toluene (25 mL) were added to a reaction flask and stirred at room temperature for 24 hours. The crude product obtained after concentrating the solvent was dissolved in methanol (60 mL). NaBH4 (28 mmol) was added in batches and stirred for 4 hours. Subsequently, the reaction was quenched with saturated ammonium chloride solution. After concentrating to remove the solvent, it was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. Subsequently, it was dissolved in dichloromethane (30 mL), DMAP (341.6 mg, 2.8 mmol), and Boc2O (9.2 g, 42.0 mmol) were added, and the reaction was carried out at 150 °C for 1 hour. Subsequently, the reaction was quenched with saturated ammonium chloride, concentrated, and purified by column chromatography to obtain S-3 (yield 81%).

[0157] Example 5

[0158] This example is different from Example 1 in that: S-2 (28.0 mmol), benzylamine (140 mmol), and toluene (50 mL) were added to a reaction flask and stirred at room temperature for 18 hours. The crude product obtained after concentrating the solvent was dissolved in tetrahydrofuran (60 mL). Sodium acetylborohydride (280 mmol) was added in batches and stirred for 8 hours. Subsequently, the reaction was quenched with saturated ammonium chloride solution. After concentrating to remove the solvent, it was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. Subsequently, it was dissolved in dichloromethane (30 mL), DMAP (341.6 mg, 2.8 mmol), and Boc2O (9.2 g, 42.0 mmol) were added, and the reaction was carried out at 0 °C for 24 hours. Subsequently, the reaction was quenched with saturated ammonium chloride, concentrated, and purified by column chromatography to obtain S-3 (yield 85%).

[0159] Example 6

[0160] This example is different from Example 1 in that: Ph2PH (215 mmol) and tetrahydrofuran (100 mL) were added to a reaction flask, cooled to -78 °C, n-butyllithium (8.6 mL, 21.5 mmol) was added, then it was warmed to room temperature and stirred for 1 hour, then cooled to -78 °C again, and a THF (10 mL) solution of the above S-3 was added, and then the temperature was raised to -78 °C and the reaction was carried out for 48 hours. After the reaction was completed, the solvent was concentrated and purified by column chromatography to obtain a white solid S-4 (yield 75%).

[0161] Example 7

[0162] This example is different from Example 1 in that Ph2PH (21.5 mmol) and tetrahydrofuran (100 mL) were added to a reaction flask, cooled to -78 °C, n-butyllithium (8.6 mL, 21.5 mmol) was added, and then the mixture was stirred at room temperature for 1 hour. After that, it was cooled to -78 °C again, and a THF (10 mL) solution of the above S-3 was added. Subsequently, the temperature was raised to 150 °C and the reaction was carried out for 6 hours. After the reaction was completed, the solvent was concentrated, and column chromatography was performed to obtain a white solid S-4 (yield 73%).

[0163] Example 8

[0164] This example is different from Example 1 in that the crude product from the previous step was dissolved in THF (5 mL) and transferred to a reaction flask. The metal manganese catalyst precursor Mn(CO)5Br (1.0 mmol) was added, and the mixture was heated to 150 °C and reacted for 6 hours. After the reaction was completed, the temperature was cooled to room temperature, the solvent was dried, the reaction flask was transferred into a glove box, washed with ether, centrifuged, and concentrated to obtain an orange-red solid [Mn]-1 (yield 90%), which is a novel tridentate pincer-shaped manganese complex.

[0165] Example 9

[0166] This example is different from Example 1 in that the crude product from the previous step was dissolved in 1,4-dioxane (5 mL) and transferred to a reaction flask. The metal manganese catalyst precursor Mn(CO)5Br (0.1 mmol) was added, and the mixture was heated to 50 °C and reacted for 36 hours. After the reaction was completed, the temperature was cooled to room temperature, the solvent was dried, the reaction flask was transferred into a glove box, washed with ether, centrifuged, and concentrated to obtain an orange-red solid [Mn]-1 (yield 85%), which is a novel tridentate pincer-shaped manganese complex.

[0167] Example 10

[0168] This example is different from Example 1 in that cyclohexylamine was replaced with benzylamine. The structure of the obtained product [Mn]-2 is as follows:

[0169]

[0170] The inventors of this case also characterized the product by NMR, high-resolution, etc. The data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.20 (d, J = 2.8 Hz, 1H), 8.10–8.01 (m, 4H), 7.74 (s, 1H), 7.44–7.35 (m, 8H), 7.31–7.29 (m, 4H), 7.25–7.20 (m, 2H), 4.90 (d, J = 13.6 Hz, 1H), 4.44 (s, 1H), 4.23–4.19 (m, 1H), 4.11–3.98 (m, 2H);13 13C NMR (101 MHz, CD2Cl2) δ 231.2, 229.5 (d, J = 17.8 Hz), 161.7 (d, J = 3.6 Hz), 152.5 (d, J = 22.2 Hz), 138.3, 138.0, 137.3, 137.1 (d, J = 3.9 Hz), 136.8, 134.9 (d, J = 10.1 Hz), 133.4, 133.2, 131.5 (d, J = 10.7 Hz), 130.9, 130.2 (d, J = 2.3 Hz), 129.3, 129.2, 128.9, 128.5, 128.3 (d, J = 9.7 Hz), 128.1 (d, J = 9.8 Hz), 127.7 (d, J = 4.5 Hz), 118.8, 61.4, 59.2; 31 31P NMR (162 MHz, CDCl3) δ 83.7. HRMS (ESI) calcd. for MnC 31 H 25 N2O2P[M-Br]: 543.1034, found: 543.1018. IR (νCO) = 1923, 1843 cm -1 .

[0171] Example 11

[0172] This example is different from Example 2 in that: cyclohexylamine is replaced by isopropylamine, and the structural formula of the finally obtained tridentate pincer manganese complex [Mn]-3 is:

[0173]

[0174] Example 12

[0175] Synthesis of tridentate pincer manganese complex [Mn]-4

[0176]

[0177] Under nitrogen protection, S-2 (1.75 g, 10 mmol) prepared in the example and THF (20 mL) were added to a reaction flask, cooled to -78 °C, CH3MgBr (12 mmol) was added, and then the mixture was stirred at room temperature for 3 hours. The reaction was quenched with water, the solvent was removed by concentration, and the residue was extracted with ethyl acetate. The combined organic phases were dried, concentrated, and purified by column chromatography to obtain S-6 (1.7 g, yield 89%).

[0178] Under nitrogen protection, S-6 (1.6 g, 8.5 mmol), pyridine (0.53 mmol, 6 mol%), and dichloromethane (30 mL) were added to a reaction flask. After cooling to 0 °C, thionyl chloride (0.8 mL, 10.6 mmol) was added, and then the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction was quenched with water and basified with saturated potassium carbonate solution. Subsequently, it was extracted with ethyl acetate. The organic phases were combined, dried, and the solvent was removed by concentration to obtain the crude product S-7, which was directly used for the next reaction.

[0179] Under nitrogen protection, a mixture of NaI (36.0 mg, 0.24 mmol), K2CO3 (662.4 mg, 4.8 mmol), cyclohexylamine (712.8 mg, 7.2 mmol), and CH3CN (10 mL) was added to a Schlenk flask, and then a CH3CN solution (10 mL) of S-7 (501.6 mg, 2.4 mmol) was added. The mixture was heated to 80 °C and stirred for 12 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the resulting residue was purified by column chromatography to obtain a yellow oil S-8 (498.8 mg, yield 76%).

[0180] Under nitrogen protection, S-8 (272 mg, 1.0 mmol) was dissolved in dichloromethane (5 mL). DMAP (12.2 mg, 0.1 mmol) and Boc2O (324 mg, 1.5 mmol) were added to the reaction mixture, and it was stirred at room temperature for 12 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the resulting residue was purified by silica gel column chromatography to obtain a yellow oil S-9 (206.9 mg, yield 56%).

[0181] Under nitrogen protection, a mixture of diphenylphosphine (133.9 mg, 0.72 mmol) and THF (3 mL) was added to a Schlenk flask. Then, at -78 °C, n-butyllithium (0.3 mL, 0.72 mmol) was added to the mixture, and it was slowly warmed to room temperature. The reaction mixture was stirred at room temperature for another 1 hour. Then, at -78 °C, a THF solution (2 mL) of S-9 was added, and the reaction mixture was stirred at 60 °C for 12 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the resulting residue was purified by silica gel column chromatography to obtain a yellow oil S-10 (167.7 mg, yield 64%).

[0182] Under nitrogen protection, Mn(CO)5Br (69 mg, 0.25 mmol), S-10 (131.4 mg, 0.3 mmol) and THF (5 mL) were added to a 25 mL Schlenk flask. The reaction mixture was stirred at 70 °C for 12 hours. The solvent was removed under vacuum, and the resulting residue was washed several times with n-hexane and diethyl ether. After simple centrifugation and concentration, an orange-red solid [Mn]-4 (129.8 mg, yield 83%) was obtained.

[0183] The inventors of this case also characterized the orange-red solid [Mn]-4 by NMR, high-resolution, etc. The data are as follows: 1 H NMR (600 MHz, CD2Cl2) δ 8.38–8.34 (m, 1H), 8.18–8.10 (m, 2H), 8.04–8.01 (m, 0.74H), 7.97–7.94 (m, 1.2H), 7.84–7.79 (m, 1H), 7.55 (d, J = 8.4 Hz, 0.66H), 7.49 (d, J = 8.4 Hz, 0.43H), 7.43–7.38 (m, 3H), 7.31–7.23 (m, 5H), 4.84–4.81 (m, 0.49H), 4.57–4.49 (m, 1H), 4.08 (d, J = 10.2 Hz, 0.69H), 3.69–3.67 (m, 1H), 3.00–2.96 (m, 0.73H), 2.80–2.76 (m, 0.5H), 2.47 (d, J = 12.6 Hz, 0.47H), 2.31–2.24 (m, 0.77H), 2.04–2.00 (m, 1H), 1.96–1.86 (m, 2H), 1.79–1.78 (m, 2H), 1.63–1.62 (m, 1H), 1.54 (br, 1H), 1.41–1.35 (m, 2H), 1.32–1.27 (m, 2H); 13CNMR(151MHz,CD2Cl2)δ232.1,231.9,167.4(d,J=3.0Hz),167.0(d,J=3.3Hz),152.7(d,J=22.3Hz),152.6(d,J=22.7Hz),138.4,138.1,138.0,137.8,137.5(d,J=4.2Hz),137.3(d,J=4.3Hz),136.7(d,J=27.5Hz),136.6(d,J=27.3Hz),135.3(d,J=9.7Hz),135.0(d,J=9.2Hz),134.7,134.5,134.1,133.8,131.9(d,J=10.3Hz),131.7(d,J=10.1Hz),131.4,130.4,130.2,129.5,128.6(m),128.1(m),127.9(d,J=4.7Hz),127.8(d,J=4.7Hz),120.0,119.3,68.2,65.8,63.3,60.4(d,J=8.8Hz),36.0,34.0,33.7,32.2,32.0,26.3,26.0,23.1,19.7,19.5,14.3; 31 P NMR(162MHz,DMSO-d6)δ84.4,84.0.HRMS(ESI)calcd.for MnC 31 H 31 N2O2P[M-Br]:549.1504,found:549.1479.IR(νCO)=1919.9,1842.6cm -1 .

[0184] Example 13

[0185] This example is different from Example 4 in that the methyl Grignard reagent is replaced by a phenyl Grignard reagent, and the structural formula of the finally obtained product, the tridentate pincer manganese complex [Mn]-5, is:

[0186]

[0187] Example 14

[0188] Synthesis of the tridentate pincer manganese complex [Mn]-6

[0189]

[0190] Under nitrogen protection, S-2 (1.8 g, 10.0 mmol) prepared in Example 1, cyclohexylamine (1.1 g, 11.0 mmol) and toluene (15 mL) were added to a reaction flask and stirred at room temperature for 12 hours. The crude product obtained after concentrating the solvent was dissolved in methanol (15 mL). NaBH4 (456 mg, 12.0 mmol) was added in batches and then stirred for 4 hours. Subsequently, the reaction was quenched with saturated ammonium chloride solution. After concentrating to remove the solvent, it was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate and then concentrated. The resulting residue was purified by silica gel column chromatography to obtain a yellow oil S-11 (1.9 g, yield 75%).

[0191] Under nitrogen protection, S-11 (1.7 g, 6.5 mmol) was dissolved in THF (15 mL). Then, at room temperature, NaH (312 mg, 13.0 mmol) was added to the reaction mixture and stirred for 1 hour, followed by the addition of CH3I (1.0 g, 7.2 mmol) and continued stirring for 12 hours. After the reaction was completed, it was quenched with water, the solvent was removed, and the residue was extracted with ethyl acetate. The organic phases were combined and dried, and the solvent was removed under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain a yellow oil S-12 (1.1 g, yield 65%).

[0192] Under nitrogen protection, Ph2PH (186.2 mg, 1.0 mmol) and tetrahydrofuran (5 mL) were added to a reaction flask. The temperature was cooled to -78 °C, n-butyllithium (0.4 mL, 1.0 mmol) was added, and then it was warmed to room temperature and stirred for 1 hour. Then it was cooled to -78 °C again, and a THF (10 mL) solution of the above S-12 was added. Subsequently, the temperature was raised to 60 °C and reacted for 12 hours. After the reaction was completed, the solvent was concentrated and column chromatographed to obtain S-13 (409.2 mg, yield 93%).

[0193] Under nitrogen protection, S-13 (219 mg, 0.5 mmol) was dissolved in THF (5 mL), the metal manganese catalyst precursor Mn(CO)5Br (123 mg, 0.45 mmol) was added, and it was heated to 70 °C and reacted for 12 hours. After the reaction was completed, the temperature was cooled to room temperature, the solvent was dried under reduced pressure, the reaction flask was transferred into a glove box and washed with ether, centrifuged, and concentrated to obtain an orange-red solid [Mn]-6 (260.0 mg, yield 90%).

[0194] The inventors of this case also characterized the orange-red solid [Mn]-6 by NMR, high-resolution, etc. The data are as follows: 11H NMR (400 MHz, CDCl3) δ 8.28 (d, J = 6.8 Hz, 1H), 8.11 (s, 1H), 7.78–7.75 (m, 3H), 7.52–7.43 (m, 3H), 7.33 (s, 7H), 5.00 (s, 0.83H), 4.59 (s, 0.25H), 3.86 (s, 1H), 3.66 (s, 1H), 2.99–2.96 (m, 1H), 2.87 (s, 0.48H), 2.56 (s, 2.61H), 1.96–1.80 (m, 3H), 1.72–1.56 (m, 2H), 1.50–1.22 (m, 4H); 13 13C NMR (101 MHz, CDCl3) δ 231.9 (d, J = 21.8 Hz), 229.7 (d, J = 26.3 Hz), 164.7 (d, J = 3.5 Hz), 153.1 (d, J = 22.1 Hz), 153.0 (d, J = 20.9 Hz), 137.3, 136.8 (d, J = 4.3 Hz), 136.2, 135.7 (d, J = 3.4 Hz), 135.3, 135.0, 134.7, 134.1 (d, J = 9.2 Hz), 133.8 (d, J = 9.4 Hz), 131.9 (d, J = 9.8 Hz), 131.0, 129.5 (d, J = 2.4 Hz), 129.4 (d, J = 2.2 Hz), 128.1 (m), 127.2 (d, J = 4.4 Hz), 120.3, 119.1, 71.1, 66.4, 65.3, 63.9, 44.9, 33.4, 31.6 (d, J = 5.2 Hz), 27.7, 26.4, 26.2, 26.0 (m), 25.5, 25.0, 22.7, 14.1; 31 31P NMR (162 MHz, CDCl3) δ 92.5, 90.0. HRMS (ESI) calcd. for MnC 31 H 31 N2O2P[M - Br]: 549.1504, found: 549.1505. IR (νCO) = 1919.7, 1843.3 cm -1 .

[0195] Example 15

[0196] This example is different from Example 12 in that the molar ratio of S - 2 to the Grignard reagent CH3MgBr is 1:0.5 and the reaction temperature is 50 °C;

[0197] The molar ratio of S - 6, dichloromethane to pyridine is 1:1:0.01, the reaction temperature is 50 °C, and the reaction time is 24 h;

[0198] The molar ratio of S-7, cyclohexylamine, K2CO3 and NaI is 1:1:1:0.01; the reaction temperature is 0 °C and the time is 24 h;

[0199] The molar ratio of S-10 to the metal manganese catalyst precursor Mn(CO)5Br is 1:2; the reaction temperature is 110 °C and the reaction time is 12 h.

[0200] Example 16

[0201] Compared with Example 12, the difference in this example is that: the molar ratio of S-2 to the Grignard reagent CH3MgBr is 1:10 and the reaction temperature is 20 °C;

[0202] The molar ratio of S-6, dichloromethane and pyridine is 1:10:5, the reaction temperature is 150 °C and the reaction time is 1 h;

[0203] The molar ratio of S-7, cyclohexylamine, K2CO3 and NaI is 1:5:10:5; the reaction temperature is 150 °C and the time is 12 h;

[0204] The molar ratio of S-10 to the metal manganese catalyst precursor Mn(CO)5Br is 10:1; the reaction temperature is 25 °C and the reaction time is 36 h.

[0205] Application Example 1

[0206] Use the prepared manganese catalyst as a catalyst for the hydrogenation degradation of polyester:

[0207]

[0208] In a glove box, add the manganese catalyst (3.0 mol%), potassium tert-butoxide (9.0 mol%), methanol (0.7 mL) and toluene (0.3 mL) to a reaction flask. After stirring for 10 minutes, add PET (0.5 mmol). Place the reaction flask in an autoclave and remove the autoclave from the glove box. Add 5 bar of hydrogen to the autoclave and react at 100 °C for 48 hours. After the reaction is completed, add the internal standard n-dodecane and monitor by GC. The yield of the product p-xylene glycol 1 is 96%.

[0209] Application Example 2

[0210]

[0211] In a glove box, a manganese catalyst (3.0 mol%), potassium tert-butoxide (9.0 mol%), methanol (0.7 mL), and toluene (0.3 mL) were added to a reaction flask. After stirring for 10 minutes, PBT (0.5 mmol) was added. The reaction flask was placed in an autoclave, and the autoclave was removed from the glove box. 5 bar of hydrogen was added to the autoclave, and the reaction was carried out at 100 °C for 48 hours. After the reaction was completed, internal standard n-dodecane was added, and the yield of the product p-xylene glycol 1 was 98% as monitored by GC.

[0212] Application Example 3

[0213] In a glove box, a manganese catalyst (1.0 mol%), potassium tert-butoxide (6.0 mol%), and methanol (1.5 mL) were added to a reaction flask. After stirring for 10 minutes, PET (0.5 mmol) was added. The reaction flask was placed in an autoclave, and the autoclave was removed from the glove box. 50 bar of hydrogen was added to the autoclave, and the reaction was carried out at 80 °C for 48 hours. After the reaction was completed, internal standard n-dodecane was added, and the yield of the product p-xylene glycol 1 was 86% as monitored by GC.

[0214] Application Example 4

[0215] In a glove box, a manganese catalyst (0.01 mol%), potassium tert-butoxide (0.01 mol%), and tetrahydrofuran (1.5 mL) were added to a reaction flask. After stirring for 10 minutes, PET (0.5 mmol) was added. The reaction flask was placed in an autoclave, and the autoclave was removed from the glove box. 50 bar of hydrogen was added to the autoclave, and the reaction was carried out at 180 °C for 12 hours. After the reaction was completed, internal standard n-dodecane was added, and the yield of the product p-xylene glycol 1 was 88% as monitored by GC.

[0216] Application Example 5

[0217] In a glove box, a manganese catalyst (5 mol%), sodium ethoxide (5 mol%), and tetrahydrofuran (1.5 mL) were added to a reaction flask. After stirring for 10 minutes, PET (0.5 mmol) was added. The reaction flask was placed in an autoclave, and the autoclave was removed from the glove box. 50 bar of hydrogen was added to the autoclave, and the reaction was carried out at 30 °C for 60 hours. After the reaction was completed, internal standard n-dodecane was added, and the yield of the product p-xylene glycol 1 was 70% as monitored by GC.

[0218] In addition, the inventors of this case also investigated the activities of other manganese catalysts, etc., and the results were similar to those of Application Examples 1-5.

[0219] It can be found from the examples that the tridentate pincer manganese complex obtained by the above technical solution of the present invention has a novel structure, a brand-new framework structure, efficient reactions, can achieve efficient hydrogenation of polyesters, and has good application prospects.

[0220] In addition, the inventor of this case also conducted tests under other conditions listed in this specification by referring to the manner of the embodiments, and achieved the same technical effects as well.

[0221] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A tridentate pincer ligand, characterized in that: The tridentate pincer ligand has a structure as shown in formula (I): Among them, R 1 Selected from C1~C 20 An alkyl or aryl group, R 2 , R 3 and R 4 Selected from H or C1~C 20 Any one or more combinations of alkyl or aryl groups.

2. A method for preparing a tridentate pincer ligand, characterized in that: include: In a protective atmosphere, 8-fluoroquinaldine and selenium dioxide are reacted to obtain substituted 8-fluoroquinoline-2-carboxaldehyde; The substituted 8-fluoroquinoline-2-carboxaldehyde is reacted with a primary amine R 3 After NH2 is mixed, a reducing agent is added, and then the reaction is quenched, and then Boc2O is added to react to obtain a product as shown in formula (III); Make lithium phosphine reagent R 1 R 1 PLi reacts with the product shown in formula (III) to obtain a product shown in formula (IV); then acid treatment is performed to obtain a tridentate pincer ligand shown in formula (V); Alternatively, the substituted 8-fluoroquinoline-2-carboxaldehyde is reacted with a Grignard reagent R 2 MgBr to obtain an alcohol as shown in formula (VI), and then react with a first base to obtain a chlorine-containing compound as shown in formula (VII); The chlorine-containing compound as shown in formula (VII) is reacted with an aminating agent R 3 R 4 NH, a second base, and an iodine-containing additive react to obtain a product as shown in formula (VIII); Make lithium phosphine reagent R 1 R 1 PLi reacts with the product shown in formula (VIII) to obtain a tridentate pincer ligand shown in formula (I); Wherein, the substituted 8-fluoroquinoline-2-carboxaldehyde has a structure as shown in formula (II): Among them, R 1 Selected from C1~C 20 An alkyl or aryl group, R 2 , R 3 and R 4 Selected from H or C1~C 20 Any one or more combinations of alkyl or aryl groups.

3. The preparation method according to claim 2, characterized in that: include: In a protective atmosphere, the mixed reaction system comprising 8-fluoroquinaldine, selenium dioxide and the first solvent is heated to 50 to 150° C. and reacted for 1 to 24 hours to obtain substituted 8-fluoroquinoline-2-carboxaldehyde; And / or, the molar ratio of 8-fluoroquinaldine to selenium dioxide is 1:0.5 to 1:10; And / or, the first solvent includes any one or a combination of two or more of N,N-dimethylformamide, dichloromethane, methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, acetone, tetrahydrofuran and toluene.

4. The preparation method according to claim 2, characterized in that: include: The substituted 8-fluoroquinoline-2-carboxaldehyde is mixed with a second solvent, and a primary amine R is added. 3 NH2 and stirred at room temperature for 12 to 24 hours, after concentrating the solvent, add the third solvent and the reducing agent, continue stirring and quench the reaction, then add Boc2O and react at 0 to 150°C for 1 to 24 hours to obtain the product shown in formula (III); and / or, the molar ratio of the substituted 8-fluoroquinoline-2-carboxaldehyde, the primary amine and the reducing agent is 1:1:1 to 1:5:10; And / or, the reducing agent includes any one or a combination of two or more of sodium borohydride, sodium cyanoborohydride, sodium acetylborohydride, lithium borohydride, lithium aluminum hydride, sodium thiosulfate and red aluminum; Preferably, the second solvent includes any one or a combination of two or more of diethyl ether, dichloromethane, N,N-dimethylformamide, methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, tetrahydrofuran and toluene; Preferably, the third solvent includes any one or a combination of two or more of methanol, ethanol, isopropanol, 1,4-dioxane and tetrahydrofuran; And / or, the preparation method comprises: making a phosphine lithium reagent R 1 R 1 PLi and the product represented by formula (III) are reacted in a fourth solvent at -78 to 150° C. for 6 to 48 hours to obtain a product represented by formula IV; And / or, the molar ratio of the product represented by formula (III) to the lithium phosphine reagent is 1:0.5 to 1:10; And / or, the fourth solvent includes any one or a combination of two or more of diethyl ether, 1,4-dioxane, and tetrahydrofuran; And / or, the preparation method comprises: subjecting the product represented by formula (IV) to acid treatment with an N-deprotection agent to obtain a tridentate pincer ligand represented by formula (V); Preferably, the molar ratio of the product represented by formula (IV), the tridentate pincer ligand represented by formula (V) and the N-deprotection agent is 1:1:1 to 1:5:

10.

5. The preparation method according to claim 2, characterized in that: include: The substituted 8-fluoroquinoline-2-carboxaldehyde is mixed with the fifth solvent and then the Grignard reagent R is added at -78°C to 50°C. 2 MgBr reaction to obtain an alcohol as shown in formula (VI); and / or, the molar ratio of the substituted 8-fluoroquinoline-2-carboxaldehyde to the Grignard reagent is 1:0.5 to 1:10; Preferably, the fifth solvent includes any one of diethyl ether, 1,4-dioxane, and tetrahydrofuran, or a combination of two or more thereof; And / or, the preparation method comprises: reacting an alcohol represented by formula (VI), thionyl chloride and a first base to obtain a chlorine-containing compound represented by formula (VII); the reaction temperature is 25 to 150° C., and the reaction time is 1 to 24 hours; Preferably, the molar ratio of the alcohol represented by formula (VI), thionyl chloride and the first base is 1:1:0.01 to 1:10:5; Preferably, the first base comprises any one or a combination of two or more of triethylamine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 4-dimethylaminopyridine, pyridine, potassium tert-butoxide, potassium methoxide, sodium methoxide, potassium ethoxide, and sodium ethoxide; And / or, the preparation method comprises: making the chlorine-containing compound represented by formula (VII), an amination reagent R 3 R 4 NH, the second base and the iodine-containing additive react at 0-150° C. for 12-24 hours to obtain a product as shown in formula (VIII); Preferably, the molar ratio of the chlorine-containing compound represented by formula (VII), the amination reagent, the second base and the iodine-containing additive is 1:1:1:0.01: to 1:5:10:5; Preferably, the second base comprises 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; And / or, the preparation method comprises: making the lithium phosphine reagent R 1 R 1 PLi and the product represented by formula (VIII) are reacted in a fourth solvent at -78 to 150° C. for 6 to 48 hours to obtain a tridentate pincer ligand represented by formula (I); Preferably, the molar ratio of the product represented by formula (VIII) to the lithium phosphine reagent is 1:0.5 to 1:

10.

6. A tridentate pincer manganese complex, characterized in that: The tridentate pincer manganese complex has a structure as shown in formula (IX): Among them, R 1 Selected from C1~C 20 An alkyl or aryl group, R 2 , R 3 and R 4 Selected from H, C1~C 20 Any one or more combinations of alkyl or aryl groups.

7. The method for preparing the tridentate pincer manganese complex according to claim 6, characterized in that: include: A tridentate pincer ligand having a structure as shown in formula (I) is prepared according to the preparation method described in any one of claims 2 to 5; The tridentate pincer ligand is reacted with a metal manganese catalyst precursor to obtain a tridentate pincer manganese complex; The metal manganese catalyst precursor includes Mn(CO)5Br; Preferably, the preparation method comprises: mixing the tridentate pincer ligand and the metal manganese catalyst precursor in a sixth solvent, and heating to react to obtain a tridentate pincer manganese complex; Preferably, 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; Preferably, the sixth solvent includes any one or a combination of two or more of tetrahydrofuran, toluene, benzene, dichloromethane, methanol, ethanol, isopropanol, ether, n-hexane and 1,4-dioxane; Preferably, the reaction temperature is 25 to 150° C., preferably 50 to 110° C., and the reaction time is 6 to 36 hours.

8. Use of the tridentate pincer manganese complex according to claim 6 as a metal catalyst in the preparation of diols by hydrogenation reaction of polyester.

9. A pincer manganese catalyst, characterized in that: The invention comprises the tridentate pincer manganese complex as claimed in claim 6.

10. A method for preparing diols by hydrogenation of polyester, characterized in that: include: The polyester, the catalyst and the alkaline substance are heated and reacted in a seventh solvent to obtain a diol compound; wherein the catalyst comprises the pincer manganese catalyst according to claim 9; The structural formula of the polyester is The structural formula of the diol compound is The R 5 and R 6 Including C1-C 20 Any one of the alkyl or aryl groups; Preferably, the molar ratio of the polyester, the catalyst and the alkaline substance is 1:0.0001:0.0001 to 1:0.05:0.05; Preferably, the seventh solvent includes any one or a combination of two or more of methanol, ethanol, isopropanol, acetonitrile, 1,4-dioxane, tetrahydrofuran, diethyl ether, n-hexane, ethylene glycol dimethyl ether, cyclohexane, benzene, toluene, and xylene; Preferably, the alkaline substance includes any one or a combination of two or more of potassium tert-butoxide, sodium tert-butoxide, sodium ethoxide, sodium methoxide, sodium hydride, potassium hydride, potassium ethoxide, potassium methoxide, potassium phosphate, potassium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, and lithium bis(trimethylsilyl)amide; Preferably, the reaction temperature is 30 to 180° C., preferably 30 to 120° C., and the reaction time is 12 to 60 hours.

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