WO2021253846A1

WO2021253846A1 - DEPROTONATED β-KETIMINE LITHIUM COMPOUND AND PREPARATION METHOD THEREFOR

Info

Publication number: WO2021253846A1
Application number: PCT/CN2021/075894
Authority: WO
Inventors: 薛明强; 徐晓娟; 康子晗; 周帅; 郑煜; 蔡玲霞
Original assignee: 苏州大学
Priority date: 2020-06-16
Filing date: 2021-02-07
Publication date: 2021-12-23
Also published as: CN111747972A

Abstract

The present invention relates to a lithium compound and a preparation method therefor, and in particular to a deprotonated β-ketimine lithium compound and a preparation method therefor. The method comprises: using m-phenylenediamine and acetylacetone as raw materials to react to prepare a ligand, mixing a small molecular organic lithium solution with a ligand solution, and then reacting to obtain the deprotonated β-ketimine lithium compound. The present invention overcomes the technical prejudice that the prior art focuses on complexes using single negative ion β-ketimine as a skeleton; and a double negative ion β-ketimine complex is disclosed for the first time, filling the blank in the prior art.

Description

Deprotonated beta-ketimide lithium compound and preparation method thereof

Technical field

The invention relates to a lithium compound and a preparation method thereof, in particular to a deprotonated β-ketimine lithium compound and a preparation method thereof.

Background technique

In recent years, the development and application of non-locene ligands has become a hot spot in the research of rare earth metal organic chemistry. β-ketimine, as an important class of non-locene ligands, is easy to synthesize and has strong bonding ability with rare earth metals. , Its charge and steric effect can be conveniently controlled by changing the substituents at the α-position and β-position, and it can coordinate with the metal through a variety of coordination methods, thereby forming structurally diverse metal complexes. However, compared with the application of β-diimine anionic ligands in organometallic chemistry, there are few reports on the application of β-ketimine anionic ligands. The existing reports focus on single anion β-ketimine On the framework of the complex [(a) Rees, Jr, WS; Just, O.; Castro, SL; Matthews, JS Inorg. Chem. 2000 , 39, 3736. (b) Schuetz, SA; Day, VW; Sommer , RD; Rheingold, AL; Belot, JA Inorg. Chem. 2001 , 40, 5292. (c) Schuetz, SA; Day, VW; Clark, JL; Belot, JA Inorg. Chem. Commun. 2002 , 5, 706. (d) Schuetz, SA; Day, VW; Rheingold, AL; Belot, JA Dalton Trans . 2003 , 4303. (e) Schuetz, SA; Silvernail, CM; Incarvito, CD; Rheingold, AL; Clark, JL; Day, VW; Belot, JA Inorg. Chem. 2004 , 43, 6203. (f) Peng, H.; Zhang, Z.; Qi, R.; Yao, Y.; Zhang, Y.; Shen, Q.; Cheng, YX Inorg. Chem. 2008 , 47, 9828. (g) Fan, L.; Wang, Y.; Yao, Y.; Wu, B. Shen, QZ Anorg. Allg. Chem. 2013 , 739].

technical problem

The present invention overcomes the technical prejudice that the prior art concentrates on complexes with a single anion β-ketimine as the skeleton, and discloses a double anion β-ketimine compound for the first time, filling the gap in the prior art.

Technical solutions

The present invention adopts the following technical scheme: a deprotonated lithium β-ketimide compound, the chemical structure of which is as follows:

.

The lithium deprotonated β-ketoimine compound of the present invention is [L ^ph ^' Li ₄ (THF) ₄ ] _2. It can be seen from its single crystal structure and crystallographic parameters that the compound is a β-ketimine with a symmetrical structure. Lithium compound and solvent THF are respectively complexed on different Li atoms. There is no coordination solvent around Li (1) atoms, two THF molecules are complexed around Li (2) atoms, and a THF molecule is complexed around Li (3) atoms and Li (4) atoms respectively. It belongs to the triclinic system, P1 space group.

The preparation method of the above-mentioned deprotonated β-ketoimid lithium compound includes the following steps: mixing a small molecule organolithium solution with a ligand solution, and then reacting to obtain a deprotonated β-ketoimid lithium compound; the chemistry of the ligand The structural formula is as follows:

.

In the present invention, in the small molecule organic lithium solution, the small molecule organic lithium includes n-butyl lithium, and the solvent is an alkyl solvent, such as hexane; in the ligand solution, the solvent is an ether solvent, such as tetrahydrofuran.

In the present invention, the reaction is at room temperature for 10-15 hours.

Furthermore, after the reaction is over, the reaction solution is heated until it is clear to obtain a clear solution; the clear solution is concentrated, centrifuged, reconcentrated, heated to clear, and naturally cooled to room temperature to obtain crystals, which are deprotonated β-ketimine lithium compounds .

In the present invention, the molar ratio of small molecule organolithium to ligand is 4:1, and this ratio has not been reported in the synthesis and application of β-ketimine anionic ligand.

In the present invention, the ligand is prepared by reacting m-phenylenediamine and acetylacetone as raw materials. Preferably, the molar ratio of m-phenylenediamine and acetylacetone is 1:2; further, the reaction of m-phenylenediamine and acetylacetone is The reaction is carried out in the presence of ethanol and p-toluenesulfonic acid; the reaction is a reflux reaction for 20-25 hours, preferably 24 hours.

Beneficial effect

There has been no report on the compound (complex) of the double anion β-ketimine ligand so far. The inventor’s group has reported on the synthesis and reaction performance of p-phenyl bridged β-ketimine bimetallic rare earth complexes, but in these complexes, each β-ketimine unit is still a single unit. Negative ions. In the present invention, when the β-ketoimino precursor L ^ph H ₂ bridged by the ortho-phenyl group is reacted with four times equivalent of n-butyl lithium hexane solution in THF, the deprotonated ortho-phenyl bridge can be conveniently obtained. Connected β-ketimine lithium compound, in which each β-ketimine unit is a double anion, which is a new compound disclosed for the first time; and the double anion β-ketimine is a kind of active Very high groups, for example, can react with small molecules containing active hydrogen and small organic molecules with unsaturated bonds. At the same time, the compound can also be used as a precursor for the further synthesis of dianionic β-ketimine rare earth metal complexes.

Description of the drawings

Figure 1 is a diagram of the crystal structure of the deprotonated β-ketimide lithium compound of the present invention.

Embodiments of the present invention

The raw materials involved in the present invention are all commercially available products. Under the preparation method of the present invention, the specific operation steps, purification methods and test methods are all conventional methods in the field; the reactions in Example 1 are all carried out in air.

Example 1: Synthesis of meta-phenyl bridged β-ketimine ligand (L ^ph H ₂ ):

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Add 150 ml of absolute ethanol, 10.8 g of m-phenylenediamine (100 mmol), 20.5 mL of acetylacetone (200 mmol), and catalytic amount of p-toluenesulfonic acid into a three-necked flask. Heat to reflux for 24 hours to obtain a reddish brown liquid and light. The yellow solid mixture was filtered with suction, and the solid was recrystallized with absolute ethanol to obtain 24.5 g of light yellow needle-like crystals, with a yield of 90%, which was the ligand L ^ph H ₂ . ¹ H NMR (400 MHz, CDCl ₃ ): δ 12.47 (2H, s, NH), 7.32-7.27 (1H, m, ArH), 6.94-6.91 (2H, m, ArH), 6.86 (1H, s, ArH) ), 5.21 (2H, s, CH=C(CH ₃ )N), 2.10 (6H, s, CH ₃ ), 2.01 (6H, s, CH ₃ ). ¹³ C NMR (101 MHz, CDCl ₃ ): δ 196.54 (COCH ₃ ), 159.62 (C=CH), 139.63 (Ar-C), 129.71 (Ar-C), 121.45 (Ar-C), 120.43 (Ar- C), 98.20 (=CH), 29.25 (CH ₃ ), 19.94 (CH ₃ ). HRMS (ESI-MS) calcd. for C ₁₆ H ₂₀ N ₂ O ₂ [M+H] ⁺ : 273.1558, found: 273.1633.

Synthesis of deprotonated phenyl-bridged β-ketoimide lithium compound [L ^ph ^' Li ₄ (THF) ₄ ] _2:

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Under ice bath conditions, add the hexane solution of n-butyllithium (19.40 mmol, 2.5 M) to the L ^ph H ₂ (4.85 mmol) tetrahydrofuran solution, the solution gradually changed from pale yellow clear liquid to light orange-red turbidity After adding 1 minute, react for 12 h at room temperature; after the reaction, heat the reaction solution (100 ^o C) to turn it into orange-red clear liquid, concentrate the clear solution to turbidity and centrifuge, and continue the supernatant Concentrate to produce broken crystals, heat to dissolve, then cool to room temperature naturally, seal the bottle, and let stand for 1h at room temperature, and light yellow crystals precipitate out [L ^ph ^' Li ₄ (THF) ₄ ] ₂ {L ^ph ^' = C ₆ H ₄ [ N(CH ₃ )C=CHCO=CH ₂ ] ₂ }, conventionally separated and dried, and 2.13 g of product was obtained with a yield of 75%. The crystal structure is shown in Figure 1. Melting point: 194.6-196.7 ^o C. ¹ H NMR (400 MHz, C ₂ D ₆ SO): δ 7.60-7.13 (2H, m, ArH), 7.00-6.96 (2H, m, ArH), 6.09 (2H, s), 4.55 (4H, s) , 1.69-1.66 (6H, m). ¹³ C NMR (101 MHz, C ₂ D ₆ SO): δ 179.53, 163.77, 154.04, 129.35, 127.83, 117.68, 116.40, 95.55, 28.88, 21.95. IR (KBr): 2972.71, 2869.81, 1590.41, 1500.86, 1468.03, 1412.07, 1360.89, 1318.03, 1280.73, 1238.47, 1146.11, 1053.76, 1019.62, 970.28, 924.75, 887.93, 806.76, 748.66 643.56.

Compound [L ^ph ^' Li ₄ (THF) ₄ ] ₂ :

.

From the single crystal structure and crystallographic parameters of the compound [L ^ph ^' Li ₄ (THF) ₄ ] _{2 we} can see that the compound is a β-ketoimide lithium compound with a symmetrical structure. The solvent THF is complexed in different Li atom. There is no coordination solvent around Li (1) atoms, two THF molecules are complexed around Li (2) atoms, and a THF molecule is complexed around Li (3) atoms and Li (4) atoms respectively. It belongs to the triclinic crystal system, P1 space group.

The crystal structure parameters of the compound [L ^ph ^' Li ₄ (THF) ₄ ] _2.

.

Comparative example: Synthesis of ethyl-bridged β-ketimide lithium compound: Under ice bath conditions, a hexane solution of n-butyllithium (20.08 mmol, 2.5 M) was added to LH ₂ (5.02 mmol, 1.126 g ) In the tetrahydrofuran solution, the solution gradually changed from a light yellow clear liquid to a brown-yellow clear liquid. After 1 minute of addition, the reaction was carried out at room temperature for 12 h. After the reaction, drain the THF, add hexane to wash twice, add THF to dissolve, and finally add hexane, precipitation occurs, centrifuge, pour the supernatant into a crystallization flask, and drain the remaining solids in the centrifuge flask. Obtained 1.09 g of yellow solid, non-deprotonated product. ¹ H NMR (400 MHz, C ₂ D ₆ SO): δ 4.46 (2H, s, CH), 3.30 (4H, s, CH ₂ ), 1.67 (6H, s, CH ₃ ), 1.64 (6H, s, CH ₃ ). ¹³ C NMR (101 MHz, C ₂ D ₆ SO): δ 174.71, 165.21, 96.71, 50.57, 28.15, 20.08.

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Synthesis of 2,6-Diisopropylanilino-2-penten-4-one sodium salt: In a two-neck round bottom flask treated with dehydration, deoxygenation and argon filling, NaH and 2 were added at a molar ratio of 4:1 , 6-Diisopropylanilino-2-penten-4-one and THF, the reaction proceeded quickly (the generated hydrogen gas was released in time). When there is no obvious bubble generation, react for two days under heating ^{in a 60 o C oil bath.} After the reaction, the excess NaH was removed by centrifugation, the supernatant was transferred to a crystallization flask, the remainder was concentrated, hexane was added, a large amount of precipitation was generated, centrifuged again, and the solid was drained to obtain a white solid with a yield of 81%. It is a non-deprotonated product. ¹ H NMR (400 MHz, C ₂ D ₆ SO): δ 6.90-6.69 (4H, m, ArH), 3.86 (1H, s, CH), 2.99-2.93 (2H, m, CH(CH ₃ ) ₂ ) , 2.29 (3H, s, CH ₃ ), 1.41 (3H, s, CH ₃ ), 1.07 (6H, s, CH ₃ ), 1.02 (6H, s, CH ₃ ). ¹³ C NMR (101 MHz, C ₂ D ₆ SO): δ 179.04, 164.44, 150.87, 138.34, 122.28, 119.96, 90.57, 27.36, 25.59, 24.48, 23.97.

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It can be seen that when the β-ketoimine ligand L ^ph H ₂ bridged by ortho-phenyl group in the present invention is reacted with four times equivalent of n-butyl lithium hexane solution in THF, the deprotonated ortho Phenyl-bridged β-ketimine lithium compound. In this compound, each β-ketimine unit is a di-anion, which is a new compound disclosed for the first time.

Furthermore, the deprotonated β-ketimide lithium compound disclosed in the present invention can be used as a catalyst to respectively catalyze the hydroboration reaction of aldehydes and ketones with pinacol borane, as follows: Example 2: [L ^ph ^' Li ₄ (THF) ₄ ] ₂ Catalyze benzaldehyde and pinacol borane borohydride reaction: under inert gas atmosphere, add benzaldehyde (106.1 μL, 1 mmol) to the reaction flask after dehydration and deoxygenation, and add pinacol with a pipette Alcohol borane (174.1 μL, 1.2 mmol), finally add 1.2 mg of catalyst [L ^ph ^' Li ₄ (THF) ₄ ] ₂ , THF (200 μL), react at room temperature for 10 minutes, use a dropper to pipette a drop into the NMR tube In, add CDCl _{3 to make a} solution. The calculated ¹ H spectrum yield is 99%. The nuclear magnetic data of the product: ¹ H NMR (400 MHz, CDCl3) δ 7.26-7.14 (m, 5H, ArH), 4.84 (s, 2H, OCH ₂ ), 1.17 (s, 12H, CH ₃ ).

After the reaction is completed, the reaction mixture in the reaction flask is filtered, and the filtrate is placed in a vacuum drying box, and excess pinacol borane and solvent THF are removed under reduced pressure to obtain a pure borate product; the following examples are the same.

Example 3: [L ^ph ^' Li ₄ (THF) ₄ ] ₂ catalyzes the synthesis of borate from p-chlorobenzaldehyde and pinacol borane: under an inert gas atmosphere, 1.2 is added to the reaction flask after dehydration and deoxygenation treatment mg catalyst [L ^ph ^' Li ₄ (THF) ₄ ] ₂ , p-chlorobenzaldehyde (140.6 mg, 1 mmol), add pinacol borane (174.1 μL, 1.2 mmol), THF (200 μL) with a pipette ), After reacting at room temperature for 10 minutes, use a dropper to pipette a drop into the NMR tube, and add CDCl _{3 to make a} solution. The calculated ¹ H spectrum yield is 98%. The NMR data of the product: ¹ H NMR (400 MHz, CDCl3) δ 7.30-7.25 (m, 5H, ArH), 4.87 (s, 2H, OCH ₂ ), 1.25 (s, 12H, CH ₃ ).

Example 4: [L ^ph ^' Li ₄ (THF) ₄ ] ₂ catalyzes the synthesis of borate from p-methylbenzaldehyde and pinacol borane: under an inert gas atmosphere, add to the reaction flask after dehydration and deoxygenation 1.2 mg of catalyst [L ^ph ^' Li ₄ (THF) ₄ ] ₂ , add p-tolualdehyde (133.5 μL, 1 mmol), pinacol borane (174.1 μL, 1.2 mmol), THF ( 200 μL), after reacting at room temperature for 10 min, use a dropper to pipette a drop into the NMR tube, and add CDCl _{3 to make a} solution. The calculated ¹ H spectrum yield is 99%. NMR data of the product: ¹ H NMR (400 MHz, CDCl3) δ 7.22 (d, J =8.0Hz, 2H, ArH), 7.12 (d, J =7.4 Hz, 2H, ArH), 4.87 (s, 2H, OCH ₂ ), 2.32 (s, 3H, CH ₃ ), 1.25 (s, 12H, CH ₃ ).

Example 5: [L ^ph ^' Li ₄ (THF) ₄ ] ₂ catalyzes the synthesis of borate from acetophenone and pinacol borane: In an inert gas atmosphere, add 1.2 mg to the reaction flask after dehydration and deoxygenation Catalyst [L ^ph ^' Li ₄ (THF) ₄ ] ₂ , use a pipette to add acetophenone (116.6 μL, 1 mmol), pinacol borane (174.1 μL, 1.2 mmol), THF (200 μL), After reacting at room temperature for 10 minutes, use a dropper to pipette a drop into the NMR tube, and add CDCl _{3 to make a} solution. The calculated ¹ H spectrum yield is 99%. The nuclear magnetic data of the product: ¹ H NMR (400 MHz, CDCl3) δ 7.37 – 7.20 (m, 5H), 5.26-5.21 (m, 1H, CH), 1.48 (d, J = 6.5Hz, 3H, CHCH ₃ ), 1.23 (s, 6H), 1.20 (s, 6H).

Example 6: [L ^ph ^' Li ₄ (THF) ₄ ] ₂ catalyzes the synthesis of borate from benzophenone and pinacol borane: Under an inert gas atmosphere, 1.2 is added to the reaction flask after dehydration and deoxygenation treatment mg catalyst [L ^ph ^' Li ₄ (THF) ₄ ] ₂ , add benzophenone (182.0 mg, 1 mmol), THF (200 μL), pinacol borane (174.1 μL, 1.2 mmol) with a pipette ), THF (200 μL), after reacting at room temperature for 10 min, pipette a drop into the NMR tube, and add CDCl _{3 to make a} solution. The calculated ¹ H spectrum yield is 98%. NMR data of the product: ¹ H NMR (400 MHz, CDCl3) δ 7.37 (d, J = 7.1Hz, 4H, ArH), 7.27 (d, J = 7.4Hz, 4H, ArH), 7.19 (d, J = 7.3 Hz, 2H, ArH), 6.18 (s, 1H, CH), 1.18 (s, 12H, CH ₃ ).

Internal standard calculation yield: add the internal standard (mesitylene (1 mmol)) in an equimolar amount,

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Claims

A kind of deprotonated β-ketoimide lithium compound, its chemical structure is as follows:

.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 1, comprising the following steps: mixing a small molecule organolithium solution with a ligand solution and then reacting to obtain a deprotonated β-ketimide lithium compound; The chemical structure of the ligand is as follows:

.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 2, wherein in the small-molecule organolithium solution, the small-molecule organolithium includes n-butyl lithium, and the solvent is an alkyl solvent; , The solvent is ether solvent.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 2, wherein the reaction is at room temperature for 10-15 hours.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 2, wherein after the reaction, the reaction solution is heated until it is clear to obtain a clear solution; the clear solution is concentrated, centrifuged, re-concentrated, and then heated to It is clarified and naturally cooled to room temperature to obtain crystals, which are deprotonated lithium β-ketimine compounds.
The method for preparing a deprotonated β-ketoimide lithium compound according to claim 2, wherein the molar ratio of the small molecule organolithium to the ligand is 4:1.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 2, wherein the ligand is prepared by reacting m-phenylenediamine and acetylacetone as raw materials.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 7, wherein the molar ratio of m-phenylenediamine and acetylacetone is 1:2; the reaction of m-phenylenediamine and acetylacetone is in ethanol, Carry out in the presence of p-toluenesulfonic acid.
The method for preparing a deprotonated β-ketimide lithium compound according to claim 7, wherein the reaction is a reflux reaction for 20-25 hours.
The use of the deprotonated lithium β-ketimide compound as claimed in claim 1 as a catalyst.