A β-ketoamine non-noble metal complex and its preparation method and application

Abstract

The present application relates to the field of materials and provides a β-ketoamine non-precious metal complex and its preparation method and application. The general structural formula of the β-ketoamine non-precious metal complex is shown in Formula I or Formula II: In Formula I, Q1 represents isopropyl; W1 represents phenyl; R 1 represents ethyl or isobutyl; in formula II, Q2 represents isopropyl; W2 represents phenyl; R 2 represents ethyl or n-butyl; M represents Zn or Mg. The β-ketoamine non-precious metal complex of the present application can be used as a catalyst for the preparation of isocyanate derivatives (such as carbamate, formamide, and N-methylamine), with high catalytic efficiency, good effect, low cost, and environmental friendliness.

Description

Technical Field

[0001] The present application relates to the field of materials, and in particular to a β-ketoamine non-noble metal complex and a preparation method and application thereof. Background Art

[0002] Isocyanates are a class of highly reactive compounds widely used in organic synthesis to produce a variety of valuable chemicals. Their ability to react with nucleophiles such as alcohols, amines, and hydrides makes them indispensable in both industrial applications and academic research. Among isocyanate derivatives, carbamates, formamides, and N-methylamines are particularly important due to their widespread applications in the pharmaceutical, agrochemical, and polymer industries.

[0003] In recent years, the use of metal catalysts to catalyze the reaction of isocyanates with alcohol compounds to prepare carbamates, and the use of metal catalysts to catalyze the gradual reduction of isocyanates to prepare formamide and N-methylamine have gradually become hot research directions for the preparation of isocyanate derivatives.

[0004] Therefore, research and development of metal catalysts with novel structure, high catalytic efficiency, good effect, low cost and green environmental protection are of great significance for the preparation of isocyanate derivatives (such as carbamate, formamide and N-methylamine). Summary of the Invention

[0005] In order to find new metal catalysts, this application has designed and synthesized a series of metal catalysts with novel structures, high catalytic efficiency, good effect, low cost and green environmental protection after extensive and in-depth research. The application of these metal catalysts in catalyzing isocyanate hydrogen alkoxylation reaction, catalyzing isocyanate monoboration reaction, and catalyzing isocyanate deoxyboration reaction is studied, which is of great significance for the preparation of isocyanate derivatives (such as carbamate, formamide and N-methylamine).

[0006] To achieve the above-mentioned invention objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a β-ketoamine non-noble metal complex, the general structural formula of which is shown in Formula I or Formula II:

[0008]

[0009] In formula I, Q1 represents isopropyl; W1 represents phenyl; R 1 represents ethyl or isobutyl;

[0010]

[0011] In formula II, Q2 represents isopropyl; W2 represents phenyl; R 2represents ethyl or n-butyl; M represents Zn or Mg.

[0012] Furthermore, the β-ketoamine non-noble metal complex described in the present application is selected from compounds having the following structure:

[0013]

[0014] In a second aspect, the present application provides a method for preparing the β-ketoamine non-noble metal complex of the first aspect. When the β-ketoamine non-noble metal complex is a compound having a structure of Formula I, the preparation method comprises the following steps:

[0015]

[0016] S1, at a first temperature, a compound having a structure of formula L and triethylaluminum (AlEt3) or diisobutylaluminum hydride ( i Bu2AlH) is reacted in a first reaction solvent to obtain a first reactant;

[0017] S2. Concentrate the first reactant and recrystallize it at a second temperature to obtain a compound of formula I.

[0018] In a third aspect, the present application provides a method for preparing the β-ketoamine non-noble metal complex of the first aspect. When the β-ketoamine non-noble metal complex is a compound having a structure of Formula II, the preparation method comprises the following steps:

[0019]

[0020] S01, at a third temperature, a compound having a structure of formula L and diethylzinc (ZnEt2) or di-n-butylmagnesium (Mg n Bu2) reacting in a second reaction solvent to obtain a second reactant;

[0021] S02. Under a nitrogen atmosphere, the second reactant is separated and dried to obtain a compound having a structure of Formula II.

[0022] In a fourth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect, or the β-ketoamine non-noble metal complex prepared by the preparation method of the second aspect or the third aspect, in catalyzing the hydrogen alkoxylation reaction of isocyanate.

[0023] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula I or Formula II is used to catalyze the reaction of isocyanate with alcohol or phenol; wherein the molar ratio of the isocyanate, alcohol or phenol, and the β-ketoamine non-precious metal complex having a structure of Formula I is 100:105:2-5, and the reaction solvent is n-hexane.

[0024] In a fifth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect or the β-ketoamine non-noble metal complex prepared by the preparation method of the third aspect in catalyzing the monohydroboration reaction of isocyanate.

[0025] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula II is used to catalyze the monohydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-precious metal complex having a structure of Formula II is 100:110:0.25~5.

[0026] In a sixth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect or the β-ketoamine non-noble metal complex prepared by the preparation method of the third aspect in catalyzing the deoxygenation hydroboration reaction of isocyanate.

[0027] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula II is used to catalyze the deoxygenated hydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-precious metal complex having a structure of Formula II is 100:310:5-10.

[0028] The beneficial effects of the present application are at least that: after extensive and in-depth research, a series of non-precious metal catalysts (β-ketoamine non-precious metal complexes) having a structure of Formula I or Formula II with novel structure, high catalytic efficiency, good effect, low cost and environmental protection have been designed and synthesized, and the application of these non-precious metal catalysts in catalyzing the hydrogen alkoxylation of isocyanates, catalyzing the monoboration of isocyanates, and catalyzing the deoxygenation of isocyanates has been studied, which is of great significance for the preparation of isocyanate derivatives (such as carbamates, formamides and N-methylamines). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 Schematic diagram of the molecular structure of compound 1 prepared in Example 1 of the present application;

[0031] Figure 2 Schematic diagram of the molecular structure of compound 2 prepared in Example 2 of the present application;

[0032] Figure 3Schematic diagram of the molecular structure of compound 3 prepared in Example 3 of the present application;

[0033] Figure 4 Schematic diagram of the molecular structure of compound 4 prepared in Example 4 of the present application;

[0034] Figure 5 The ligand L prepared in Example 1 of the present application is 1 H NMR spectrum;

[0035] Figure 6 Compound 1 prepared in Example 1 of the present application 1 H NMR spectrum;

[0036] Figure 7 Compound 2 prepared in Example 2 of the present application 1 H NMR spectrum;

[0037] Figure 8 Compound 3 obtained in Example 3 of the present application 1 H NMR spectrum;

[0038] Figure 9 is compound 4 obtained in Example 4 of the present application 1 H NMR spectrum;

[0039] Figure 10 The compound 1 provided in the embodiment of the present application catalyzes the reaction of p-toluene isocyanate and methanol. 1 H NMR spectrum;

[0040] Figure 11 The compound 1 provided in the embodiment of the present application catalyzes the reaction of p-toluene isocyanate and methanol. 13 C NMR spectrum;

[0041] Figure 12 Schematic diagram of the reaction mechanism of the hydroalkoxylation reaction of isocyanate catalyzed by compound 1 provided in the examples of the present application;

[0042] Figure 13 Schematic diagram of the reaction mechanism of the hydroboration reaction of isocyanate catalyzed by compound 3 provided in the examples of the present application. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the following is a further detailed description of this application in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application, but the implementation methods of this application are not limited thereto.

[0044] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the amounts of the experimental reagents used, unless otherwise specified, are the amounts used in routine experimental procedures; and the experimental methods, unless otherwise specified, are conventional methods.

[0045] All chemicals used in the examples herein were commercially available and used without further purification. Solvents were dried and purified according to standard procedures before use. All experimental manipulations were performed using Schlenk technology under a pure nitrogen atmosphere or in an Etelux Lab 2000 glove box. NMR spectra were recorded at room temperature on a Bruker Ascend II 400 spectrometer.

[0046] In the first aspect, this embodiment provides a β-ketoamine non-noble metal complex, the general structural formula of which is shown in Formula I or Formula II:

[0047]

[0048] In formula I, Q1 represents isopropyl; W1 represents phenyl; R 1 represents ethyl or isobutyl;

[0049]

[0050] In formula II, Q2 represents isopropyl; W2 represents phenyl; R 2 represents ethyl or n-butyl; M represents Zn or Mg.

[0051] Furthermore, the β-ketoamine non-noble metal complex of the embodiment of the present application is selected from compounds having the following structure:

[0052]

[0053] The compounds 1 to 4 provided in the examples of the present application were tested using a single crystal X-ray diffractometer to determine the absolute structure (molecular structure) of the compounds 1 to 4 (also referred to as compounds C1 to C4). The test results are shown in Figures 1 to 4 .

[0054] See also Figure 1 and Figure 2The molecular structures of compound 1 (also referred to as compound C1) and compound 2 (also referred to as compound C2) provided in the embodiments of the present application are both monomer structures, wherein compound 1 belongs to the monoclinic system and compound 2 belongs to the orthorhombic system. The nitrogen atom and oxygen atom of the β-ketoamine ligand of compound 1 (compound with structural formula L) are connected to the metal center aluminum atom, and two ethyl groups are respectively connected to the aluminum atom to form a distorted tetrahedral structure. The nitrogen atom and oxygen atom of the β-ketoamine ligand of compound 2 (compound with structural formula L) are connected to the metal center aluminum atom, and two isobutyl groups are respectively connected to the aluminum atom to form a distorted tetrahedral structure.

[0055] See also Figure 3 and Figure 4 The molecular structures of compound 3 (also referred to as compound C3) and compound 4 (also referred to as compound C4) provided in the examples of the present application are both symmetrical binuclear metal dimer structures. Among them, compound 3 belongs to the triclinic system, and compound 4 belongs to the monoclinic system. Compound 3 and compound 4 are bridged by the metal center and oxygen atom of two monomers to form a dimer structure. The sum of the internal angles of the four-membered ring composed of the two metal centers and the two oxygen atoms is 360°, indicating that the four atoms are almost in the same plane. In compound 3, the two ethyl groups are respectively connected to the zinc atom. In compound 4, the two n-butyl groups are respectively connected to the magnesium atom.

[0056] The crystallographic data and structure refinement parameters of compounds 1 to 4 provided in the examples of this application are shown in Tables 1 and 2.

[0057] Table 1 Crystallographic data and structure refinement parameters of compounds 1 and 2

[0058]

[0059] Table 2 Crystallographic data and structure refinement parameters of compounds 3 and 4

[0060]

[0061]

[0062] The meanings of the parameters of the crystallographic data in Tables 1 and 2 are shown in Table 3.

[0063] Table 3 Explanation of the meaning of parameters of crystallographic data

[0064]

[0065]

[0066] In a second aspect, the present invention provides a method for preparing the β-ketoamine non-noble metal complex of the first aspect. When the β-ketoamine non-noble metal complex is a compound having a structure of Formula I, the preparation method comprises the following steps:

[0067]

[0068] S1, at a first temperature, a compound having a structure of formula L and triethylaluminum (AlEt3) or diisobutylaluminum hydride ( i Bu2AlH) is reacted in a first reaction solvent to obtain a first reactant;

[0069] S2. Concentrate the first reactant and recrystallize it at a second temperature to obtain a compound of formula I.

[0070] Furthermore, in step S1, the first temperature is room temperature, generally 25°C to 30°C; the first reaction solvent is at least one of n-hexane, toluene, tetrahydrofuran, or diethyl ether. Preferably, the first reaction solvent is n-hexane.

[0071] Furthermore, in step S2, the second temperature is -25°C to -10°C.

[0072] In a third aspect, the present application provides a method for preparing the β-ketoamine non-noble metal complex of the first aspect. When the β-ketoamine non-noble metal complex is a compound having a structure of Formula II, the preparation method comprises the following steps:

[0073]

[0074] S01, at a third temperature, a compound having a structure of formula L and diethylzinc (ZnEt2) or di-n-butylmagnesium (Mg n Bu2) reacting in a second reaction solvent to obtain a second reactant;

[0075] S02. Under a nitrogen atmosphere, the second reactant is separated and dried to obtain a compound having a structure of Formula II.

[0076] Furthermore, the third temperature is room temperature, generally 25° C. to 30° C.; the second reaction solvent is at least one of toluene, n-hexane, tetrahydrofuran, or diethyl ether. Preferably, the second reaction solvent is toluene.

[0077] In a fourth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect, or the β-ketoamine non-noble metal complex prepared by the preparation method of the second aspect or the third aspect, in catalyzing the hydrogen alkoxylation reaction of isocyanate.

[0078] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula I or Formula II is used to catalyze the reaction of isocyanate with alcohol or phenol; wherein the molar ratio of the isocyanate, alcohol or phenol, and the β-ketoamine non-precious metal complex having a structure of Formula I is 100:105:2-5, and the reaction solvent is n-hexane or toluene.

[0079] In some embodiments, the general procedure for the alkoxylation of isocyanate catalyzed by Compound 1 (Compound C1) is as follows: All reactions were carried out under a nitrogen atmosphere. In a 10 mL Schlenk flask equipped with a magnetic stir bar in a glove box, isocyanate (1 mmol), alcohol or phenol (1.05 mol), Compound C1 (0.02 mmol) and 0.5 mL of n-hexane solution were mixed. 1 HNMR, 13 The reaction process was monitored by C NMR, and the disappearance of the hydroxyl proton and the appearance of a new product indicated that the reaction was complete. The crude product obtained by the reaction was washed with n-hexane solution.

[0080] In a fifth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect or the β-ketoamine non-noble metal complex prepared by the preparation method of the third aspect in catalyzing the monohydroboration reaction of isocyanate.

[0081] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula II is used to catalyze the monohydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-precious metal complex having a structure of Formula II is 100:110:0.25~5.

[0082] In some embodiments, the general procedure for the monohydroboration of isocyanates catalyzed by Compound 3 (Compound C3) is as follows: All reactions were carried out under a nitrogen atmosphere. In a 10 mL Schlenk flask equipped with a magnetic stir bar in a glove box, isocyanate (1 mmol), HBpin (1.1 mol) and Compound C3 (0.01 mmol) were mixed. 1 H NMR, 13 The reaction process was monitored by C NMR, and the disappearance of the reactants and the appearance of new products indicated that the reaction was complete. The crude product obtained by the reaction was washed with n-hexane solution.

[0083] In a sixth aspect, the present application further provides the use of the β-ketoamine non-noble metal complex of the first aspect or the β-ketoamine non-noble metal complex prepared by the preparation method of the third aspect in catalyzing the deoxygenation hydroboration reaction of isocyanate.

[0084] Furthermore, under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula II is used to catalyze the deoxygenated hydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-precious metal complex having a structure of Formula II is 100:310:5-10.

[0085] In some embodiments, the general procedure for the deoxygenated hydroboration of isocyanates catalyzed by Compound 3 (Compound C3) is as follows: All reactions were carried out under a nitrogen atmosphere. In a 10 mL Schlenk flask equipped with a magnetic stir bar in a glove box, isocyanate (1 mmol), HBpin (pinacol borane) (3.1 mol) and Compound C3 (0.05 mmol) were mixed and heated in an oil bath at 70°C for 8 h. 1 H NMR, 13 The reaction was monitored by C NMR, which indicated completion of the reaction by the disappearance of the reactants and the appearance of new products. The reaction mixture was hydrolyzed with 1M HCl in ether (10 mL). Volatiles were removed under reduced pressure, and the residue was washed 3 times with ethyl acetate (5 mL each time) to obtain the pure desired product as an ammonium salt.

[0086] The present application has been subjected to multiple tests, and part of the test results are cited as a reference to further describe the invention in detail, which will be described in detail in conjunction with specific embodiments.

[0087] Example 1

[0088] (1) Synthesis of ligand L (i.e., compound having the structure of formula L):

[0089] The structural formula of ligand L is:

[0090] Benzoylacetone (20 mmol) was added to 20 mL of dry toluene solution and stirred evenly to obtain a toluene solution of benzoylacetone; 1.1 equivalents of 2,6-diisopropylaniline was then gradually added dropwise to the toluene solution of benzoylacetone to obtain a first mixed solution; 5 mol% of p-toluenesulfonic acid was added to the first mixed solution as a catalyst, and the mixture was mixed to obtain a second mixed solution, which was then heated to reflux at 120° C. for 36 hours, and water was removed using a water separator to obtain a crude product; the crude product was dried under reduced pressure, and the crude product after reduced pressure drying was dissolved in n-hexane for crystallization to obtain a white solid (i.e., ligand L) with a yield of 71%.

[0091] (2) Synthesis of Compound 1:

[0092] In an ice bath at 0°C, 1 mL of a 1 mmol / mL n-hexane solution of Et3Al (triethylaluminum) was added to 10 mL of a dry n-hexane solution containing 1 mmol of ligand L, and the mixture was mixed to obtain a first reaction mixture. The first reaction mixture was then heated to room temperature and stirred for 12 hours to obtain a first reactant. The first reactant was concentrated to 5 mL and stored in a refrigerator at -10°C for 3 days for low-temperature recrystallization to obtain Compound 1. The yield of Compound 1 was 66%.

[0093] Example 2

[0094] (1) Synthesis of ligand L:

[0095] Ligand L was synthesized according to the synthesis method of ligand L in Example 1.

[0096] (2) Synthesis of Compound 2:

[0097] In an ice bath at 0°C, 1 mL of 1 mmol / mL i A n-hexane solution of Bu2AlH (diisobutylaluminum hydride) was added to 10 mL of a dry n-hexane solution containing 1 mmol of ligand L and mixed to obtain a second reaction mixture. The temperature of the second reaction mixture was then slowly raised to room temperature and stirred for 12 hours to obtain a first reactant. The first reactant was concentrated to 5 mL and stored in a refrigerator at -10°C for 3 days for low-temperature recrystallization to obtain compound 2. The yield of compound 2 was 61%.

[0098] Example 3

[0099] (1) Synthesis of ligand L:

[0100] Ligand L was synthesized according to the synthesis method of ligand L in Example 1.

[0101] (2) Synthesis of compound 3:

[0102] In an ice bath at 0°C, 1 mL of a 1 mmol / mL toluene solution of ZnEt2 (diethylzinc) was added to 10 mL of a dry toluene solution containing 1 mmol of ligand L, and the mixture was mixed to obtain a third reaction mixture. This third reaction mixture was then heated to room temperature and stirred for 12 hours to obtain a second reactant. The second reactant was then isolated under a nitrogen atmosphere to obtain a yellow solid, which was then dried to obtain Compound 3. The yield of Compound 3 was 79%.

[0103] Example 4

[0104] (1) Synthesis of ligand L:

[0105] Ligand L was synthesized according to the synthesis method of ligand L in Example 1.

[0106] (2) Synthesis of compound 4:

[0107] In an ice bath at 0°C, 1 mL of 1 mmol / mL Mg n A toluene solution of Bu2 (di-n-butylmagnesium) was added to 10 mL of a dry toluene solution containing 1 mmol of ligand L and mixed to obtain a fourth reaction mixture. The fourth reaction mixture was then heated to room temperature and stirred for 12 hours to obtain a second reactant. The second reactant was then separated under a nitrogen atmosphere to obtain a yellow solid, which was then dried to obtain compound 4. The yield of compound 4 was 83%.

[0108] An asymmetric β-ketoamine ligand (i.e., ligand L) reacts with 1.1 equivalents of a metal reagent (triethylaluminum, diisobutylaluminum hydride, diethylzinc, or di-n-butylmagnesium) at room temperature to yield clean metal complexes (Compound 1, Compound 2, Compound 3, or Compound 4). For the synthesis of Compound 1 and Compound 2, n-hexane was used as the reaction solvent. After completion of the reaction, the corresponding metal complex (Compound 1 or Compound 2) was directly transferred to a refrigerator for low-temperature crystallization. For the synthesis of Compound 3 and Compound 4, toluene solution was used as the solvent, resulting in the formation of a large amount of light yellow solids (Compound 3 and Compound 4).

[0109] The above-mentioned ligand L and compounds 1 to 4 synthesized in Examples 1 to 4 were identified:

[0110] Ligand L and compounds 1 to 4 1 H NMR spectrum Figures 5 to 9 As shown. Figures 5 to 9 It can be seen that compounds 1 to 4 1 The H NMR spectrum showed that the -NH peak of the free β-ketoamine ligand disappeared completely at 12.57 ppm. At the same time, new signals of the alkyl group connected to the metal were observed in the negative field and high field, indicating the formation of compounds 1-4.

[0111] A series of experimental studies were conducted on the catalytic performance of compounds 1 to 4 (compounds C1 to C4) prepared in Examples 1 to 4 of the present application. The test results show that the compounds 1 to 4 provided in the examples of the present application catalyze the hydroalkoxylation reaction of p-toluene isocyanate with benzyl alcohol, and all have excellent catalytic effects. Based on this, the compounds 1 to 4 in the examples of the present application can be used as catalysts for catalyzing the hydroalkoxylation reaction of isocyanates. Compounds 3 to 4 have excellent catalytic effects on catalyzing the monohydroboration reaction and deoxyhydroboration reaction of isocyanates.

[0112] Listed below are some of the research tests and test results on the catalytic properties of compounds 1 to 4 provided in the examples of this application.

[0113] Experiment 1: Hydroalkoxylation of p-toluene isocyanate with benzyl alcohol catalyzed by compound 1 (compound C1)

[0114]

[0115] In a nitrogen-protected glove box, p-toluene isocyanate (Compound 1a) (1.00 mmol), benzyl alcohol (Compound 2a) (1.05 mmol), reaction solvent (0.5 mL) and Compound 1 (Compound C1) were added to a 10 mL Schlenk bottle, which was then placed in a constant temperature heating magnetic stirrer for reaction. 1 H NMR, 13 The reaction process was monitored by C NMR, and the disappearance of the hydroxyl proton and the appearance of new products indicated that the reaction was complete. The crude product obtained by the reaction was washed with n-hexane solution. 1 After the reaction was completed, the catalytic yield of the crude product (compound 3a) was detected by HNMR.

[0116] Among them, the reaction conditions and test results of the hydroalkoxylation reaction of p-toluene isocyanate and benzyl alcohol catalyzed by compound 1 are shown in Table 4.

[0117] Table 4

[0118]

[0119] In Table 4, “rt” indicates room temperature, “neat” indicates no reaction solvent (ie, no reaction solvent is added), “Tol” indicates toluene, “DCM” indicates dichloromethane, and “Hex” indicates n-hexane.

[0120] From the test results of Test 1 in Table 4, it can be seen that no compound C1 (Compound 1) and reaction solvent were added to the reaction system, and the reaction was carried out at room temperature for 12 hours. 1 H NMR analysis revealed that the yield of compound 3a was only 35%.

[0121] The experimental results of Experiments 2 to 4 in Table 4 show that the addition of 5% mmol of Compound C1 and 0.5 mL of toluene (as the reaction solvent) to the reaction system and a reaction at room temperature for 30 minutes significantly increased the product yield from 35% to 93%. Furthermore, the addition of 5% mmol of Compound C1 and 0.5 mL of toluene (as the reaction solvent) to the reaction system and a reaction at 40-60°C for 1 hour significantly increased the product yield from 35% to 99%. This demonstrates that the addition of Compound C1, a reaction solvent, and an increase in reaction temperature can significantly improve product yield.

[0122] From the test results of experiments 5 to 7 in Table 4, it can be seen that when the amount (loading amount) of compound C1, reaction temperature and reaction time remain unchanged, the product yield is the highest when n-hexane is added to the reaction system as the reaction solvent, which can reach 99%.

[0123] From the test results of Experiments 8 and 9 in Table 4, it can be seen that when the loading (amount) of Compound C1 in the reaction system is reduced to 2 mmol%, the product yield can reach 99%. When the loading (amount) of Compound C1 in the reaction system is reduced to 1 mmol%, the product yield is reduced to 89%.

[0124] Therefore, the reaction conditions for the hydroalkoxylation of p-toluene isocyanate and benzyl alcohol catalyzed by compound 1 are preferably as follows: the amount of compound C1 is 2 mmol%, the reaction solvent is n-hexane (amount is 0.5 mL), the reaction temperature is room temperature, and the reaction time is 30 min.

[0125] Experiment 2: Compound 1 (Compound C1) catalyzes the hydroalkoxylation of various isocyanates and substituted alcohols

[0126]

[0127] Among them, R 3 、R 4 represents an alkyl group or an aryl group.

[0128] In a nitrogen-protected glove box, isocyanate (1 mmol), alcohol or phenol (1.05 mol), compound C1 (0.02 mmol, 2 mmol%) and 0.5 mL of n-hexane solution were added to a 10 mL Schlenk flask, which was then stirred on a magnetic stirrer and reacted at 60 °C. 1 H NMR, 13 The reaction progress was monitored by C NMR, indicating completion of the reaction as indicated by the disappearance of hydroxyl protons and the appearance of new products. After completion of the reaction, the crude products (compounds 3a-3q) were washed with n-hexane. The reaction times and product yields of the crude products are shown in Table 5.

[0129] Table 5 Reaction time and product yield of crude products (compounds 3a-3q)

[0130]

[0131]

[0132] Table 5 shows that, in most cases, compound C1 catalyzes the hydroalkoxylation of isocyanates, achieving high yields within 30 minutes at room temperature. p-Toluene isocyanate reacts rapidly with various substituted alcohols, completing the conversion in just 30 minutes at room temperature.

[0133] The experimental results of compounds 3a to 3d show that the activity of phenol is greatly reduced due to the direct effect of the phenyl group on the hydroxyl group. Even if the reaction temperature is increased to 60°C, it takes 6 hours to achieve a high product yield (95%).

[0134] From the experimental results of compounds 3e to 3h, it can be seen that changing the position of the substituent on p-toluene isocyanate gradually reduces the reactivity of isocyanate with benzyl alcohol as the methyl group shifts from the para position to the ortho position, but has little effect on its reactivity with methanol, which may be due to steric hindrance.

[0135] From the experimental results of compounds 3i and 3j, it can be seen that when there is an electron-donating group methoxy group at the para position of the benzene ring, the reaction can also be completed with excellent yield, and the product yield can reach 99%.

[0136] The experimental results of compounds 3g, 3k, and 3l show that compared with electron-donating groups, when the substituents at the ortho-position of the benzene ring are electron-withdrawing groups, the reaction activity is slightly improved, but it still takes 2 hours to completely react with benzyl alcohol.

[0137] The experimental results for compounds 3m–3q indicate that, under identical conditions, the hydroalkoxylation of cyclohexyl isocyanate yields of 99% for the preparation of carbamate products were excellent. Furthermore, aliphatic substrates also afforded the desired product in relatively high yields when the reaction time was extended to 6 h.

[0138] Experiment 3: Amplification of the Hydroalkoxylation of p-Anisylphenyl Isocyanate Catalyzed by Compound 1 (Compound C1)

[0139]

[0140] In a gram-scale hydroalkoxylation reaction system of p-methoxyphenyl isocyanate and benzyl alcohol, 2 mmol% of compound C1 was added as a catalyst, n-hexane was used as the reaction solvent, and the reaction was carried out at room temperature for 30 minutes to obtain a carbamate product with a product yield of up to 97%.

[0141] Experiment 4: Reaction Mechanism of Hydroalkoxylation of Isocyanate Catalyzed by Compound 1 (Compound C1)

[0142] See also Figure 10 and Figure 11First, compound C1 is reacted with 2.2 equivalents of p-toluene isocyanate and methanol, respectively. 1 H NMR spectroscopy analysis showed that the reaction of compound C1 with isocyanate did not change compared with the original data. 1 H NMR spectrum showed that the nuclear magnetic resonance signal of aluminum ethyl group disappeared completely, while 1 A new signal was detected at δ3.41ppm by H NMR. 13 A new signal was also detected at δ49.7 ppm in C NMR, which was attributed to the characteristic group of the new compound LAlOMe produced by the reaction of compound C1 with methanol.

[0143] Based on the above test results, the reaction mechanism of the compound C1 in the embodiment of the present application catalyzing the alkoxylation of isocyanate hydrogen can be deduced as follows: Figure 12 The methanol-stabilized aluminum ethyl complex (i.e., compound C1) deprotonates by releasing an ethane molecule to produce the active aluminum oxymethyl compound (CatA). CatA coordinates to the nitrogen atom of the isocyanate to form Int-1A, followed by C=N bond migratory insertion to form the quaternary transition state Int-2A. Finally, Int-2A coordinates to the oxygen atom of another equivalent of alcohol to form Int-3A, which regenerates CatA through protonolysis and releases the desired carbamate.

[0144] Experiment 5: Application of Compound 3 (Compound C3) in Catalyzing Monohydroboration of Isocyanates

[0145]

[0146] In a nitrogen-protected glove box, isocyanate (1.00 mmol), HBpin (1.1 mmol) and compound C3 (0.0025-0.05 mmol, 0.25-5 mmol%) were added to a 10 mL Schlenk flask, which was then placed on a magnetic stirrer for reaction. 1 After the reaction was completed, the yield of the crude product (compound 4a) was detected by H NMR.

[0147] Among them, the reaction conditions and test results of the hydroboration reaction of p-toluene isocyanate catalyzed by compound 3 are shown in Table 6.

[0148] Table 6

[0149]

[0150] In Table 6, “rt” indicates room temperature, “neat” indicates no reaction solvent (ie, no reaction solvent is added), “Tol” indicates toluene, “DCM” indicates dichloromethane, and “Hex” indicates n-hexane.

[0151] From the experimental results of Experiment 1 in Table 6, it can be seen that when the loading amount (dosage) of Compound C3 is 0.25 mmol% and no reaction solvent is added, p-toluene isocyanate and HBpin react rapidly to obtain the desired product N-borylformamide with a high yield (91%) within 15 minutes.

[0152] The experimental results of Experiments 2 to 4 in Table 6 show that when the loading (dosage) of Compound C3 is increased to 1 mmol%, the yield of N-borylformamide can be increased to 97%. When the loading of Compound C3 is gradually increased to 2 mmol% and 5 mmol%, the yield of N-borylformamide does not change much. This may be due to the rapid generation of solid N-borylformamide, which prevents the p-toluene isocyanate from fully reacting, thereby preventing the complete conversion of the reactants.

[0153] From the experimental results of experiments 5 to 7 in Table 6, it can be seen that when 1 mmol% of compound C3 was added to the reaction system, the reaction time was controlled to 15 min, and reaction solvents of different polarities (dichloroethane (DCM), n-hexane (Hex), toluene (Tol)) were added to prepare N-borylformamide, the product yield was not improved.

[0154] From the experimental results of Experiment 8 in Table 6, it can be seen that in a blank control experiment carried out at room temperature, there is almost no conversion of toluene isocyanate and HBpin in the absence of a catalyst for 2 hours, which indicates that compound C3 is necessary for the hydroboration of isocyanate.

[0155] Therefore, the reaction conditions for the hydroboration reaction of p-toluene isocyanate catalyzed by compound 3 are preferably: an amount of compound 3 of 1 mmol%, no reaction solvent added, and a reaction time of 15 min.

[0156] Experiment 6: Hydroboration of Various Isocyanates Catalyzed by Compound 3 (Compound C3)

[0157]

[0158] Here, R represents an alkyl group and an aryl group.

[0159] In a nitrogen-protected glove box, isocyanate (1.00 mmol), HBpin (1.1 mmol), 0.5 mL of n-hexane and compound C3 (0.0025-0.05 mmol, 0.25-5 mmol%) were added to a 10 mL Schlenk flask, which was then placed on a magnetic stirrer for reaction.1 The catalytic yields of the crude products (compounds 4a-4n) after the reaction were determined by H NMR. The reaction times and product yields of the crude products are shown in Table 7.

[0160] Table 7 Reaction time and product yield of crude products (compounds 4a-4n)

[0161]

[0162]

[0163] As shown in Table 7, all substrates achieved excellent yields of 93% to 99% under the above reaction conditions within 2 h.

[0164] From the experimental results of compounds 4a to 4c, it can be seen that the catalytic activity decreases slightly with the transfer of the methyl substituent on the benzene ring from the para position to the ortho position, which may be due to the influence of steric hindrance.

[0165] From the experimental results of compound 4d, it can be seen that when the para position of the benzene ring is connected to a stronger electron-donating group, the product yield can reach 98% within 15 minutes.

[0166] The experimental results of compounds 4e to 4h show that the effect of the electron-withdrawing chlorine atom on the substrate reactivity is not much different from that of the electron-donating group, but the difference in activity between the para and ortho positions is more obvious. A reaction time of 1 hour is required to achieve a high yield of o-chlorophenyl isocyanate.

[0167] From the experimental results of compound 4i, it can be seen that when the benzene ring is connected to both electron-withdrawing and electron-donating groups, the yield of N-borylformamide product is high, reaching 93%.

[0168] From the experimental results of compound 4j, it can be seen that compound C3 has good chemical selectivity in the hydroboration reaction of 4-cyanophenyl isocyanate in the presence of other unsaturated functional groups.

[0169] From the experimental results of compound 4k, it can be seen that the substrate naphthyl isocyanate can be completely converted into the N-boryl formamide product within 15 minutes under the above reaction conditions.

[0170] From the experimental results of compounds 41 to 4n, it can be seen that the hydroboration reaction of aliphatic isocyanates catalyzed by compound C3 (compound 3) can be reduced with quantitative yields, although the reaction time required for the aliphatic substrate is longer.

[0171] Experiment 7: Deoxyhydroboration of Isocyanate with HBpin Catalyzed by Compound 3 (Compound C3)

[0172]

[0173] In a nitrogen-protected glove box, p-toluene isocyanate (1.00 mmol), HBpin (3.1 mmol) and compound C3 (0.05-0.1 mmol, 5-10 mmol%) were added to a 10 mL Schlenk bottle, which was then placed on a magnetic stirrer for reaction. 1 After the reaction was completed, the catalytic yield of the crude product (compound 5a) was determined by H NMR.

[0174] Among them, the reaction conditions and test results of the deoxygenative hydroboration of p-toluene isocyanate catalyzed by compound 3 are shown in Table 8.

[0175] Table 8

[0176]

[0177] In Table 8, “neat” indicates no reaction solvent (ie, no reaction solvent was added), “Tol” indicates toluene, and “Hex” indicates n-hexane.

[0178] The results of Experiment 1 in Table 8 show that pure N-borylmethylamine can be prepared by reacting p-toluene isocyanate and HBpin in the presence of catalyst compound C3. The molar ratio of p-toluene isocyanate to HBpin was 1:3.1, the loading of compound C3 was 10 mmol%, the reaction temperature was 80°C, and the reaction time was 12 hours. The product yield reached 99%.

[0179] From the test results of experiments 2 to 4 in Table 8, it can be seen that when other conditions are the same and only the loading rate (amount) of the catalyst (compound C3) is different, 5 mmol% of the catalyst is added to the reaction system and the reaction temperature is 70°C for 8 hours to achieve complete conversion of the reactant (p-toluene isocyanate).

[0180] From the test results of test numbers 5 to 6 in Table 8, it can be seen that when the loading amount of the catalyst (compound C3) is reduced to 2 mmol% or the reaction temperature of the reaction system is reduced to 60° C., the yield of the obtained product decreases slightly.

[0181] From the test results of test numbers 7 and 8 in Table 8, it can be seen that when Hex (n-hexane) or Tol (toluene) is added to the reaction system as a reaction solvent, the yield of the product is 97%.

[0182] Therefore, the reaction conditions for the deoxygenative hydroboration of p-toluene isocyanate catalyzed by compound 3 are preferably as follows: an amount of compound 3 of 5 mmol%, no reaction solvent added, a reaction temperature of 70° C., and a reaction time of 8 h.

[0183] Experiment 8: Hydroboration of Isocyanate Catalyzed by Compound C3

[0184]

[0185] Wherein, R represents an alkyl group (Alkyl) or an aryl group (Aryl).

[0186] In a nitrogen-protected glove box, isocyanate (1.00 mmol), HBpin (1.1 mmol) and compound C3 (0.0025-0.05 mmol, 0.25-5 mmol%) were added to a 10 mL Schlenk bottle, which was then placed on a magnetic stirrer for reaction. After the reaction, the mixture was hydrolyzed with 1 M HCl in ether. 1 After the reaction, the crude products (compounds 5a-5t) were detected by H NMR to obtain a catalytic yield of 5.1 equivalents of HBpin. The yields of the crude products (compounds 5a-5t) are shown in Table 9.

[0187] Table 9 Yield of crude product (compounds 5a-5t)

[0188]

[0189]

[0190]

[0191] The experimental results for compounds 5a-5n in Table 9 show that all substrates were converted in high yields under the optimized conditions. Substrates with both electron-donating and electron-withdrawing substituents were converted to the corresponding N-methylamine products in excellent yields.

[0192] The experimental results for compound 5o in Table 9 indicate that ortho-substituted substrates are less active than para-substituted substrates due to steric hindrance, similar to the monohydroboration of isocyanates. However, under the optimized reaction conditions described above, treatment of p-cyanophenyl isocyanate with 5.1 equivalents of HBpin resulted in the reduction of both the cyano and NCO groups.

[0193] From the test results of compounds 5p to 5t in Table 9, it can be seen that naphthyl isocyanate, biphenyl isocyanate and aliphatic isocyanate can be quantitatively converted in excellent yields under the above-mentioned optimized reaction conditions.

[0194] Experiment 9: Amplification of the Monohydroboration of p-Methoxyphenyl Isocyanate Catalyzed by Compound 3 (Compound C3)

[0195]

[0196] In the reaction system of the monohydroboration reaction of p-methoxyphenyl isocyanate catalyzed by compound C3, 1 mmol% of compound C3 is added as a catalyst and the reaction is carried out at room temperature for 15 minutes to obtain N-boryl formamide product with a yield of up to 93%.

[0197] Experiment 10: Reaction Mechanism of Hydroboration of Isocyanate Catalyzed by Compound 3 (Compound C3)

[0198] In order to further study the reaction mechanism of the isocyanate hydroboration reaction catalyzed by compound C3, some stoichiometric experiments were conducted in the present examples. When compound C3 reacted alone with 1 equivalent of isocyanate, 1 The H NMR spectrum showed no difference from the original data. Therefore, it can be inferred that the ethyl group on compound C3 first undergoes hydrogen exchange with HBpin to form EtBpin and the corresponding zinc hydride. After compound C3 is mixed with HBpin, 11 The change of B NMR spectrum confirms this. Although the reaction of organozinc with HBpin to form zinc hydride seems simple, there has been no report on the direct separation of zinc hydride from the reaction of organozinc with HBpin. The present invention also conducted a stoichiometric reaction of HBpin and Zn-Et complex (Compound C3). 1 HNMR spectrum monitoring, although the Zn-H signal can not be seen, but the reduction of the ethyl group signal peak was observed in the nuclear magnetic spectrum of the system after the reaction. In addition, the signal of ethyl boric acid pinacol ester Et-Bpin was also observed, which is consistent with the 11 B NMR corresponds.

[0199] Based on the above test results, the reaction mechanism of the isocyanate hydroboration reaction catalyzed by compound C3 in the present embodiment can be deduced as follows: Figure 13 , compound C3 and HBpin undergo metathesis to form the Zn-H species CatB. In the first step, CatB reacts with isocyanate to produce a zinc complex (Int-1B). Next, the reaction between the intermediate Int-1B and HBpin provides N-borylformamide and regeneration of the catalyst CatB. In addition, the catalyst CatB reacts with N-borylformamide to produce the intermediate Int-2B. After the reaction of Int-2B and HBpin, N-, O-bis(boryl)amine appears and the catalyst CatB is regenerated. Subsequently, the reaction between N-, O-bis(boryl)amine and the catalyst CatB allows the formation of N-borylmethylamine and Int-3B. Finally, the reaction of Int-3B and HBpin produces the byproduct O(Bpin)2 and regenerates the catalyst CatB, closing the catalytic cycle.

[0200] In summary, this application synthesized a series of non-precious metal complexes stabilized by β-ketoamine ligands (β-ketoamine non-precious metal complexes having the structure of Formula I or Formula II), and determined the molecular structures of these compounds by X-ray single crystal diffraction and nuclear magnetic resonance spectroscopy; at the same time, the catalytic performance of these compounds in the reduction reaction of isocyanates was also studied. In the absence of any organic base or co-catalyst, the green and environmentally friendly compound 1 was used for the first time to catalyze the hydroalkoxylation reaction of isocyanates, and a variety of isocyanates were reduced to carbamates with wide applications in excellent yields. Furthermore, compound 3 was used to catalyze the hydroboration reaction of isocyanates, and based on this, a technical solution for converting isocyanates into N-borylformamide and N-methylamine was provided.

[0201] In addition, the present application also provides a reaction mechanism of the hydroalkoxylation reaction of isocyanate catalyzed by compound 1 and a reaction mechanism of the hydroboration reaction of isocyanate catalyzed by compound 3.

[0202] The green and environmentally friendly β-ketoamine non-precious metal complex β provided in this application can replace traditional precious metal catalysts and be used to catalyze the reduction of isocyanates into isocyanate derivatives (such as carbamate, formamide and N-methylamine), which is of great significance for the preparation of isocyanate derivatives.

[0203] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A β-ketoamine non-noble metal complex, characterized in that: Its general structural formula is shown in Formula I or Formula II: In formula I, Q1 represents isopropyl; W1 represents phenyl; R 1 represents ethyl or isobutyl; In formula II, Q2 represents isopropyl; W2 represents phenyl; R 2 represents ethyl or n-butyl; M represents Zn or Mg.

2. The β-ketoamine non-noble metal complex according to claim 1, characterized in that The β-ketoamine non-noble metal complex is selected from compounds having the following structure:

3. A method for preparing the β-ketoamine non-noble metal complex according to claim 1 or 2, characterized in that: When the β-ketoamine non-noble metal complex is a compound having a structure of Formula I, the preparation method comprises the following steps: S1. Reacting a compound having a structure of Formula L with triethylaluminum or diisobutylaluminum hydride in a first reaction solvent at a first temperature to obtain a first reactant; S2. Concentrate the first reactant and recrystallize it at a second temperature to obtain a compound of formula I.

4. A method for preparing the β-ketoamine non-noble metal complex according to claim 1 or 2, characterized in that: When the β-ketoamine non-noble metal complex is a compound having a structure of Formula II, the preparation method comprises the following steps: S01. At a third temperature, reacting a compound having a structure of Formula L with diethylzinc or di-n-butylmagnesium in a second reaction solvent to obtain a second reactant; S02. Under a nitrogen atmosphere, the second reactant is separated and dried to obtain a compound having a structure of Formula II.

5. Use of the β-ketoamine non-noble metal complex according to claim 1 or 2, or the β-ketoamine non-noble metal complex prepared by the preparation method according to claim 3 or 4, in catalyzing the hydrogen alkoxylation reaction of isocyanate.

6. The use according to claim 5, characterized in that Under a nitrogen atmosphere, a β-ketoamine non-precious metal complex having a structure of Formula I or Formula II is used to catalyze the reaction of isocyanate with an alcohol or phenol; wherein the molar ratio of the isocyanate, the alcohol or phenol, and the β-ketoamine non-precious metal complex having the structure of Formula I is 100:105:2-5, and the reaction solvent is n-hexane.

7. Use of the β-ketoamine non-noble metal complex according to claim 1 or 2, or the β-ketoamine non-noble metal complex prepared by the preparation method according to claim 4, in catalyzing the monohydroboration reaction of isocyanate.

8. The use according to claim 7, characterized in that Under a nitrogen atmosphere, a β-ketoamine non-noble metal complex having a structure of Formula II is used to catalyze the monohydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-noble metal complex having a structure of Formula II is 100:110:0.25-5.

9. Use of the non-noble metal complex of β-ketoamine according to claim 1 or 2, or the non-noble metal complex of β-ketoamine obtained by the preparation method according to claim 4, in catalyzing the deoxygenative hydroboration reaction of isocyanate.

10. The use according to claim 9, characterized in that Under a nitrogen atmosphere, a β-ketoamine non-noble metal complex having a structure of Formula II is used to catalyze the deoxygenated hydroboration reaction of isocyanate and pinacol borane; wherein the molar ratio of the isocyanate, pinacol borane, and the β-ketoamine non-noble metal complex having a structure of Formula II is 100:310:5-10.

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