CN101967165B - Bridge chain bis-Schiff base-cobalt complex and synthesis method thereof as well as application thereof - Google Patents

Abstract

The invention relates to a novel bridge chain double Schiff base-cobalt complex, a synthesis method thereof and a catalyst application thereof in hydrolysis reactions of various epoxy compounds. Experiments have shown that the bridged double Schiff base-cobalt complex of the present invention exhibits high catalytic activity and excellent enantioselectivity in the hydrolytic kinetic resolution of racemic epoxy, especially the ability to achieve high-efficiency Synthesis of chiral epoxy compounds and chiral 1,2-diol compounds.

Description

Bridged chain double Schiff base-cobalt complex and its synthesis method and application

technical field

The present invention relates to a novel bridged chain double Schiff base (Salen) complex, in particular to a bridged chain double Schiff base-cobalt complex and its synthesis method and application.

Background technique

Chiral epoxy compounds and chiral 1,2-diol compounds are important intermediates in organic synthesis. Using chiral epoxy compounds or chiral 1,2-diol compounds as starting materials, various pharmaceutical and pesticide intermediates with high optical purity can be prepared. The hydrolytic kinetic resolution of racemic epoxides is an efficient method for the synthesis of chiral epoxides and chiral 1,2-diols. In 1997, the Jacobsen group successfully applied the hydrolysis kinetic resolution method to the resolution of terminal epoxy for the first time (Jacobsen, E.N.Science, 1997, 277, 936), and the catalyst used was a mononuclear Schiff base-Co complex substances (US5929232, WO03018520A1, US2003073855A1). A number of catalytic systems have been reported one after another, such as the Schiff base-Co catalyst (Jacobsen, E.N.J.Am.Chem.Soc., 1999, 121, 4147) immobilized on polystyrene resin, methylene bridge chain Dimeric Schiff base-Co catalysts (Kureshy, R.I. Journal of Molecular Catalysis A: Chemical, 2002, 179, 73) and oligomer forms of Schiff base-Co catalysts (Jacobsen, E.N. Tetrahedron: Asymmetry, 2003, 14 , 3633), etc. However, most of these existing catalysts have the disadvantages of low catalytic activity or low selectivity.

Contents of the invention

Aiming at the deficiencies of the above-mentioned existing catalysts, the present invention provides a novel bridged double Schiff base-cobalt complex and a synthesis method thereof, hoping to improve the synergistic effect of this type of catalyst through the synergistic effect of the catalyst double metal coordination center. Activity and efficiency, add a class of new products for the catalyst field; The present invention also provides a kind of purposes of described bridge chain double Schiff base-cobalt complex, that is, after activation, be used for catalytic terminal epoxy compound Hydrolytic kinetic resolution reactions, e.g. for the catalytic synthesis of epoxy compounds and diol compounds of high optical purity.

The bridged chain double Schiff base-cobalt complex provided by the invention has the following general formula:

one of them:

R ¹ , R ² , and R ³ are independently selected from hydrogen, C _1-6 alkyl or phenyl substituted by R ^x , R ^x ′, preferably C _1-6 alkyl, for example: methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, isopentyl, cyclopentyl or cyclohexyl, tert-butyl is further recommended;

代表手性的

其中的：n＝2～6的整数，R⁴为C_1-6烷基、含4～8个碳的环烷基或R^x、R^x′取代的苯基；推荐

代表手性的

Chiral

Among them: n = an integer of 2 to 6, R ⁴ is a C _1-6 alkyl group, a cycloalkyl group containing 4 to 8 carbons, or a phenyl group substituted by R ^x , R ^x ′; recommended

Chiral

The bridge chain is a covalent bond structural unit selected from dibasic acids with the following structures:

The linking position of the bridge chain is generally at the position of the carboxyl group of the above-mentioned groups.

The aforementioned R ^x and R ^x ' are respectively selected from hydrogen, C _1-4 hydrocarbon group, C _1-4 alkoxy group, phenyl, benzyl, 1-naphthyl or 2-naphthyl. Another general formula of the bridged double Schiff base-cobalt complex provided by the invention is as follows:

及桥链如上所述；X是有机酸根，所述的有机酸根来源于如下基团或取代的如下基团的有机酸：C1-C4的羧酸、樟脑磺酸、苯甲酸、甲磺酸、苯磺酸或苯甲酸；所述的取代基是卤素、硝基或C1-C4的烷基，且所述取代基是单取代或多取代，例如：乙酸、三氟乙酸、三氟甲磺酸、2，4-二硝基苯磺酸、3-硝基苯磺酸、对甲基苯磺酸、苯磺酸、樟脑磺酸、对硝基苯甲酸、苯甲酸等。where R ¹ , R ² , R ³ ,

and the bridge chain as above; X is an organic acid radical, and the organic acid radical is derived from the following groups or substituted organic acids of the following groups: C1-C4 carboxylic acid, camphorsulfonic acid, benzoic acid, methanesulfonic acid, Benzenesulfonic acid or benzoic acid; the substituent is halogen, nitro or C1-C4 alkyl, and the substituent is mono-substituted or multi-substituted, for example: acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid , 2,4-Dinitrobenzenesulfonic acid, 3-nitrobenzenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, camphorsulfonic acid, p-nitrobenzoic acid, benzoic acid, etc.

The synthetic method of the bridged chain double Schiff base-cobalt complex provided by the invention: first synthesize the bridge chain double Schiff base ligand, then react it with tetrahydrate cobalt acetate in an organic solvent; the organic solvent used here Can be selected from chloroform, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, tetrahydrofuran, diethyl ether, methanol, ethanol, isopropanol, N,N-dimethylformamide or dimethylsulfoxide wait.

The synthetic method of bridge chain double Schiff base ligand involved in the present invention is as follows:

的取代的5-羟基水杨醛和二羧酸

在有机极性溶剂中，缩合剂和催化量的4-二甲氨基吡啶存在下，室温下反应1～60小时，制得桥连的双水杨醛

所述的取代水杨醛、二羧酸、缩合剂和4-二甲氨基吡啶的摩尔投料比为10∶5∶10∶1；1) by the structural formula as

Substituted 5-hydroxysalicylaldehydes and dicarboxylic acids

In an organic polar solvent, in the presence of a condensing agent and a catalytic amount of 4-dimethylaminopyridine, react at room temperature for 1 to 60 hours to prepare bridged salicylaldehyde

The molar ratio of the substituted salicylaldehyde, dicarboxylic acid, condensing agent and 4-dimethylaminopyridine is 10:5:10:1;

的取代水杨醛单亚胺与步骤1)的产物-桥连的双水杨醛，在有机溶剂中，反应温度0～60℃下，以1～4∶1的摩尔比反应10～80小时，制得桥连双希夫碱配体

2) The structural formula is

The substituted salicylaldehyde monoimine and the product of step 1)-bridged salicylaldehyde, in an organic solvent, at a reaction temperature of 0-60°C, reacted for 10-80 hours at a molar ratio of 1-4:1 , to prepare the bridged double Schiff base ligand

The specific recommendation is as follows:

Using dichloromethane as a solvent, in the presence of N, N'-diisopropylcarbodiimide (DIC) and a catalytic amount of 4-dimethylaminopyridine (DMAP), replace salicylaldehyde 1 and dicarboxylic acid 2 in React at room temperature for 1 to 60 hours to obtain bridged salicylaldehyde 3, and the feed ratio is: the molar ratio of salicylaldehyde 1, carboxylic acid 2, DIC and DMAP is 10:5:10:1; The salicylaldehyde 4 reacts in chloroform at zero degrees Celsius with a molar ratio of 1:1 to prepare the reaction intermediate 6, and directly synthesizes a bridged double Schiff base with the bridged double salicylaldehyde 3 obtained without separation. Ligand 7, the reaction temperature of this step is from 0°C to room temperature, and the molar ratio of compound 6 to salicylaldehyde 3 is 1-4:1.

The preparation method (as shown in the following formula) of bridge chain double Schiff base-cobalt complex 8 involved in the present invention: by the double Schiff base ligand 7 of covalent bond bridge chain and cobalt acetate tetrahydrate in organic solvent The reaction obtains the double Schiff base-cobalt complex 8 of the covalent bond bridge chain, the reaction molar ratio of the double Schiff base ligand 7 and cobalt acetate tetrahydrate is 1: 1～10, and the reaction temperature is - 10°C to 100°C, the reaction time is 1 to 48 hours; the organic solvent used is recommended to be selected from: chloroform, dichloromethane, carbon tetrachloride, tetrahydrofuran, 1,2-dichloroethane, ether, alcohol (such as methanol , ethanol, isopropanol), toluene, N, N-dimethylformamide or at least one of dimethyl sulfoxide.

The double Schiff base-cobalt complex 8 bridged by a covalent bond is activated with an organic acid in the presence of oxygen to generate a double Schiff base-cobalt complex 9 bridged by a covalent bond. The reaction molar ratio of the double Schiff base-cobalt complex 8 and the organic acid is 1: 2～10, the reaction temperature is 0～50° C., and the reaction time is 1～24 hours; the organic acid is as described above;

The structural formulas of the double Schiff base ligand 7, double Schiff base-cobalt complex 8, and double Schiff base-cobalt complex 9 are as follows:

wherein R ¹ , R ² , R ³ , R ⁴ , X and the bridge chain are as described above.

Specific recommendation: Ligand 7 is dissolved in an organic solvent, and then a methanol solution of cobalt acetate tetrahydrate is added dropwise. After the addition is complete, stir at room temperature for 1 to 48 hours. The precipitated red solid is collected by filtration, washed thoroughly with methanol, and dried in vacuum. Here, the molar ratio of cobalt acetate tetrahydrate and ligand 7 is 1-10:1.

The bridged chain double Schiff base-cobalt complex provided by the present invention can be used as a catalyst, and is recommended to catalyze the hydrolysis kinetic resolution reaction of terminal epoxy compounds, and is further recommended to be used to catalyze the hydrolysis of racemized terminal epoxy compounds Kinetic resolution of reactions to synthesize optically active diols and epoxides. The catalyst used in the reaction, such as complex 9, can be generated in situ. The complex 9 obtained by organic acid activation has a good catalytic effect.

其中的R选自C1-C20的烷基、芳基或末端带有醚、羧酸酯、卤素等官能团的烷基，可以为：甲基、乙基、正丙基、异丙基、正丁基、异丁基、异戊基、环戊基、环己基、以及其它各种直链或带支链的烷基，也可以为氯甲基、苄氧甲基、烷氧羰基或R^x、R^x’取代的苯基，这里R^x、R^x′与前述相同；推荐选自如下的结构：The structure of the racemic terminal epoxy compound is:

Among them, R is selected from C1-C20 alkyl, aryl or alkyl with functional groups such as ether, carboxylate, and halogen at the end, which can be: methyl, ethyl, n-propyl, isopropyl, n-butyl base, isobutyl, isopentyl, cyclopentyl, cyclohexyl, and other straight-chain or branched-chain alkyl groups, and can also be chloromethyl, benzyloxymethyl, alkoxycarbonyl or R ^x , Phenyl substituted by R ^x ', where R ^x and R ^x ' are the same as above; a structure selected from the following is recommended:

Take the reaction catalyzed by complex 8 as an example to illustrate as follows:

Racemized epoxy compound, organic solvent and bridged double Schiff base-cobalt complex 8, organic acid, water (it is recommended to keep the reaction system in contact with the air, and gradually add H ₂ O dropwise). After the reaction, distillation is recommended Sexual epoxy and diol products. Wherein adding the mol ratio of organic acid and bridged double Schiff base-cobalt complex 8 is 2～20: 1, the mol ratio of racemic epoxy compound and bridged double Schiff base-cobalt complex 8 is 100000-100:1, the molar ratio of racemic epoxy compound to water is 1-10:5, the recommended reaction temperature is room temperature, further recommended 0-50°C, and the recommended reaction time is 3-200 hours. The organic solvent recommended chloroform, methylene chloride, carbon tetrachloride, 1,2-dichloroethane, tetrahydrofuran, ether, alcohol (such as methanol, ethanol, isopropanol), toluene, N, N-dimethyl formamide or dimethyl sulfoxide.

Description of drawings

FIG. 1 is an X-ray crystal diffraction pattern of compound 8a synthesized in Example 1.

Specific implementation method

The present invention will be described in further detail and completely below in conjunction with the examples, but the content of the present invention will not be limited.

Example 1

The synthetic method of the bridged double Schiff base-cobalt complex of the present invention is described in detail with the synthesis of the bridged double Schiff base-cobalt complex 8a as an example (the synthesis reaction process is shown in the figure below):

Step 1: Synthesis of Compound 3a from Compounds 1a and 2a

Add compound 1a (775mg, 4.0mmol), cis-5-norbornene-endo-2,3-dicarboxylic acid (363mg, 2.0mmol) and DMAP (4-dimethylaminopyridine) (49mg , 0.4mmol), added dichloromethane (8mL) and DMF (NN-dimethylformamide) (0.8mL) after pumping argon, stirred for 10 minutes and cooled to 0°C, added DIC (N, N'- Diisopropylcarbodiimide) (0.53g, 4.2mmol) was kept at 0°C and stirred for 10 minutes, raised to room temperature and stirred for 72 hours, TLC detected that the reaction was completed, dichloromethane (50mL) was added to the reaction solution, and 0.1M Wash with hydrochloric acid (20 mL), wash with saturated NaCl aqueous solution (3×30 mL), dry over anhydrous Na ₂ SO ₄ , filter, remove the solvent under reduced pressure, and separate by column chromatography (petroleum ether:ethyl acetate=8:1) to give a white solid 0.816g, yield 86%. mp167-168°C; ¹ H NMR (300MHz, CDCl ₃ ) δ1.32(s, 18H), 1.52(d, 1H, J=8.7Hz), 1.65(d, 1H, J=8.4Hz), 3.41(s , 2H), 3.68(s, 2H), 6.41(s, 2H), 7.13(d, 2H, J=2.7Hz), 7.15(d, 2H, J=3.0Hz), 9.72(s, 2H), 11.69 (s, 2H) ppm; MALDI-MS, m/z=534.9[M+H] ⁺ ; Anal. Calcd for C ₃₁ H ₃₄ O ₈ : C, 69.65; H, 6.41%.Found: C, 69.64; H , 6.32%.

The second step: synthesis of compound 6a from compounds 4a and 5a

Add R, R-cyclohexanediamine 5a (0.493g, 4.32mmol) into a 100mL three-necked flask equipped with a constant pressure dropping funnel, add chloroform (10mL) to dissolve, cool to 0°C, and drop through the constant pressure dropping funnel Add 3,5-di-tert-butyl salicylaldehyde 4a (1.012g, 4.32mmol) in chloroform (10mL), and keep stirring at 0°C for 48 hours after the dropwise addition to obtain compound 6a, which is directly used in the next reaction without isolation.

Step 3: Synthesis of Compound 7a from Compounds 3a and 6a

分子筛搅拌48小时，过滤后用二氯甲烷洗涤，减压浓缩。将所得粗产物经柱层析分离(石油醚∶乙酸乙酯＝30∶1)得黄色泡状固体150mg，收率58％。m.p.159-160℃；[α]_D ²⁰＝-256.4(c＝0.52，CHCl₃)；¹H NMR(300MHz，CDCl₃)δ1.28(s，18H)，1.29(s，9H)，1.32(s，9H)，1.44(s，18H)，1.47-1.61(m，6H)，1.69-1.77(m，4H)，1.87-1.99(m，8H)，3.34(br，6H)，3.60(s，2H)，6.34(br，2H)，6.67(s，1H)，6.74(d，1H，J＝2.7Hz)，6.88，(t，2H，J＝3.0Hz)，7.02(t，2H，J＝3.0Hz)，7.35(d，2H，J＝2.4Hz)，8.08(s，1H)，8.17(s，1H)，8.34(d，2H，J＝3.3Hz)，13.61(br，2H)13.86(br，2H)ppm；MALDI-MS，m/z＝1159.7[M+H]⁺；Anal.Calcd for C₇₃H₉₈N₄O₈：C，75.61；H，8.52；N，4.83％.Found：C，75.27；H，8.58；N，4.68％。Add the chloroform solution of 3a (400mg, 0.72mmol, in 10mL) dropwise to the solution of 6a, rise to room temperature after the dropwise addition, add

Molecular sieves were stirred for 48 hours, filtered, washed with dichloromethane, and concentrated under reduced pressure. The resulting crude product was separated by column chromatography (petroleum ether: ethyl acetate = 30:1) to obtain 150 mg of a yellow foamy solid, with a yield of 58%. mp159-160°C; [α] _D ²⁰ = -256.4 (c = 0.52, CHCl ₃ ); ¹ H NMR (300 MHz, CDCl ₃ ) δ 1.28 (s, 18H), 1.29 (s, 9H), 1.32 (s , 9H), 1.44(s, 18H), 1.47-1.61(m, 6H), 1.69-1.77(m, 4H), 1.87-1.99(m, 8H), 3.34(br, 6H), 3.60(s, 2H ), 6.34(br, 2H), 6.67(s, 1H), 6.74(d, 1H, J=2.7Hz), 6.88, (t, 2H, J=3.0Hz), 7.02(t, 2H, J=3.0 Hz), 7.35(d, 2H, J=2.4Hz), 8.08(s, 1H), 8.17(s, 1H), 8.34(d, 2H, J=3.3Hz), 13.61(br, 2H) 13.86(br , 2H) ppm; MALDI-MS, m/z=1159.7[M+H] ⁺ ; Anal. Calcd for C ₇₃ H ₉₈ N ₄ O ₈ : C, 75.61; H, 8.52; N, 4.83%.Found: C , 75.27; H, 8.58; N, 4.68%.

Step 4: Synthesis of bridged double Schiff base-cobalt complex 8a from ligand 7a

Add ligand 7a (1.16g, 1.0mmol) to a 100mL reaction tube, add dichloromethane (10mL) to dissolve, dissolve 0.5 g (2.0mmol) of cobalt acetate tetrahydrate in methanol (20mL) and add dropwise to the above ligand In dichloromethane solution, stirred for 2 hours, a red solid was separated out, filtered and washed with methanol, and after vacuum drying, 1.02 grams of red solid was obtained, with a yield of 80%, and the complex structure was confirmed by X-ray crystal diffraction analysis (see Fig. 1 ).

Step 5: Activation of the bridged double Schiff base-cobalt complex:

Cobalt complex 8a (127mg) was dissolved in toluene (2mL), and acetic acid (48mg) was added, followed by open reaction at room temperature for 2 hours, and concentrated under reduced pressure to remove the solvent. The obtained crude product was dissolved in a small amount of dichloromethane, n-hexane was added to precipitate the complex, filtered, and vacuum-dried to obtain 132 mg of a brown solid, with a yield of 95%. MALDI-MS, m/z=1273.4; Anal. Calcd for C ₇₇ H ₁₀₀ Co ₂ N ₄ O ₁₂ : C, 66.46; H, 7.24; N, 4.03%.Found: C, 66.38; H, 7.26; N, 4.12%.

The hydrolysis reaction of the epoxy compound is catalyzed by the bridged double Schiff base-cobalt complex of the present invention, and the bridged double Schiff base-cobalt complex 8a or 9a is taken as an example to describe in detail as follows:

Embodiment 2 uses 9a to catalyze the hydrolysis kinetic resolution reaction of propylene oxide

Add racemic propylene oxide (7 mL, 0.1 mol) and bridged double Schiff base-cobalt complex 9a (0.01 mol%) into a 50 mL three-necked flask, gradually add H ₂ O (0.9 mL, 0.05 mol), After the reaction was detected by GC, (R)-1,2-propylene oxide (97% ee) was obtained by normal pressure distillation, and (S)-1,2-propanediol (95% ee) was obtained by vacuum distillation.

Embodiment 3 uses 9a to catalyze the hydrolysis kinetic resolution reaction of propylene oxide

The bridged double Schiff base-cobalt complex 8a (127mg) was dissolved in toluene (2mL), and acetic acid (48mg) was added, followed by open reaction at room temperature for 6 hours, and concentrated under reduced pressure to remove the solvent. The obtained crude product was dissolved in a small amount of dichloromethane, and n-hexane was added to precipitate the complex, filtered, and vacuum-dried to obtain 136 mg of brown solid, yield: 98%.

Add the above-mentioned activated catalyst (0.01mol%) in racemic propylene oxide (7mL, 0.1mol), keep the reaction system in contact with air, add water (0.9mL, 0.05mol) dropwise at room temperature, and monitor the reaction progress by GC. After completion, two products were separated by rectification: (R)-1,2-propylene oxide (96%ee) and (S)-1,2-propanediol (95%ee).

Embodiment 4 uses camphorsulfonic acid as the organic acid of activated divalent cobalt complex

In the reactor, add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8a (0.01mol%) successively, add camphorsulfonic acid (0.05mol%), keep the reaction system energy Expose to air, then slowly add H ₂ O (0.7 equivalent) dropwise at room temperature. After the reaction is detected by GC, rectification separates (R)-1,2-propylene oxide (96% ee) and (S)-1 , 2-Propanediol (92% ee).

Embodiment 5 uses 2,4-dinitrosulfonic acid as the organic acid of activated divalent cobalt complex

Add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8a (0.01mol%) to the reactor successively, add 2,4-dinitrosulfonic acid (0.05mol%) ), keep the reaction system in contact with the air, then slowly add H ₂ O (0.5 equivalent) dropwise at room temperature, after the GC detection reaction is completed, rectification and separation (R)-1,2-propylene oxide (98% ee) and (S)-1,2-propanediol (94% ee).

Embodiment 6 uses trifluoroacetic acid as the organic acid of activated divalent cobalt complex

In the reactor, add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8a (0.01mol%) successively, add trifluoroacetic acid (0.05mol%), keep the reaction system energy Expose to air, then slowly add H ₂ O (0.6 equivalent) dropwise at room temperature. After the reaction is detected by GC, rectification separates (R)-1,2-propylene oxide (96% ee) and (S)-1 , 2-Propanediol (92% ee).

Example 7: Referring to the synthesis method of the bridged double Schiff base-cobalt complex 8a, bridged double Schiff base-cobalt complexes 8b-8v were synthesized as shown in the figure below:

Example 8: 8e catalyzes the hydrolysis reaction of propylene oxide through the activation of p-toluenesulfonic acid

In the reactor, add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8e (0.01mol%) in sequence, add p-toluenesulfonic acid (0.05mol%), and keep the reaction system Can be exposed to air, then slowly add H ₂ O (0.7 equivalent) dropwise at room temperature, after the reaction is detected by GC, rectification and separation (R)-1,2-propylene oxide (98% ee) and (S)- 1,2-Propanediol (93% ee).

Example 9: 8e is activated by trifluoromethanesulfonic acid to catalyze the hydrolysis reaction of propylene oxide

Add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8e (0.005mol%) to the reactor successively, add trifluoromethanesulfonic acid (0.05mol%), keep the reaction The system can be exposed to air, and then slowly add H ₂ O (0.7 equivalent) dropwise at room temperature. After the reaction is detected by GC, rectification separates (R)-1,2-propylene oxide (95% ee) and (S) - 1,2-Propanediol (90% ee).

Example 10: 8e is activated by 3-nitrobenzenesulfonic acid to catalyze the hydrolysis reaction of propylene oxide

Add racemic propylene oxide (7mL, 0.1mol) and bridged double Schiff base-cobalt complex 8e (0.007mol%) to the reactor successively, add 3-nitrobenzenesulfonic acid (0.05mol%), Keep the reaction system in contact with the air, then slowly add H ₂ O (0.7 equivalents) dropwise at room temperature. After the reaction is detected by GC, rectification separates (R)-1,2-propylene oxide (97% ee) and ( S)-1,2-Propanediol (92% ee).

Embodiment 11: With every kind of bridging chain double Schiff base-cobalt complexes 8a-8v synthesized in embodiment 7 as catalyst after on-site activation of p-nitrobenzoic acid, with reference to the test method of the epoxy hydrolysis reaction of the foregoing embodiment, The hydrolysis reaction of propylene oxide was carried out respectively, and the results are shown in Table 1.

Table 1: Kinetic resolution of propylene oxide hydrolysis catalyzed by bridged double Schiff base-cobalt complexes

Reaction conditions: propylene oxide 100mmol, bridged double Schiff base-cobalt (0.01mol%), p-nitrobenzoic acid (0.06mol%), water 50mmol, solvent-free reaction.

Example 12: According to the reaction results of Example 11, we used 8e as the catalyst precursor and p-nitrobenzoic acid as the activator to test the applicability of the catalytic system to the substrate.

As shown in Table 2, different epoxy substrates are selected, and the kinetic resolution is carried out with reference to the experimental conditions using propylene oxide as the substrate. The results are listed in Table 2. The substrates applicable to this catalytic system are not limited to those listed in the table. The structure of the columns.

Table 2: Hydrolysis kinetic resolution of epoxy compounds catalyzed by bridged double Schiff base-cobalt complex 8e

Reaction conditions: epoxy compound 200mmol, 8e (0.005mol%), p-nitrobenzenesulfonic acid (0.05mol%), water 100mmol, solvent-free reaction.

From the above experimental results, it can be seen that the bridged double Schiff base-cobalt complex of the present invention exhibits high catalytic activity and excellent enantioselectivity in the hydrolytic kinetic resolution of racemic epoxy, especially capable of achieving Efficient synthesis of chiral epoxides and chiral 1,2-diols.

Claims (9)

1. a bridge chain double Schiff base-cobalt complex, is characterized in that, has following general formula:

one of them: R ¹ , R ² , R ³ are independently selected from hydrogen or C _1-6 alkyl;

Chiral

or

Wherein R ⁴ is phenyl, n=2～4 integer; The bridge chain is a covalent bond structural unit selected from dibasic acids with the following structures: 2. A bridged double Schiff base-cobalt complex, characterized in that it has the following general formula: where R ¹ , R ² , R ³ ,

and the bridge chain as claimed in claim 1; X is an organic acid radical, and the organic acid radical is derived from acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3-nitrobenzene Sulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, camphorsulfonic acid, p-nitrobenzoic acid or benzoic acid. 3. bridge chain double Schiff base-cobalt complex according to claim 1, is characterized in that, described C _1-6 alkyl is methyl, ethyl, n-propyl, isopropyl, n-propyl Butyl, tert-butyl, sec-butyl, isobutyl or isopentyl. 4. a kind of synthetic method of double Schiff base-cobalt complex compound as claimed in claim 1, is characterized in that, comprises the steps: a) From the structural formula to Substituted 5-hydroxysalicylaldehydes and dicarboxylic acids

In an organic polar solvent, in the presence of a condensing agent and a catalytic amount of 4-dimethylaminopyridine, react at room temperature for 1 to 60 hours to prepare bridged salicylaldehyde

Described structural formula is

The molar feed ratio of substituted 5-hydroxy salicylaldehyde, dicarboxylic acid, condensation agent and 4-dimethylaminopyridine is 10:5:10:1; b) The structural formula is

Substituting salicylaldehyde monoimine and the product of step a)-bridged salicylaldehyde, in an organic solvent, at a reaction temperature of 0-60° C., reacting with a molar ratio of 1-4:1 for 10-80 hours , to prepare the bridged double Schiff base ligand

c) The bridged double Schiff base ligands prepared by step b) react with cobalt acetate tetrahydrate in an organic solvent, and the reaction molar ratio of the bridged double Schiff base ligands and cobalt acetate tetrahydrate is 1 : 1 to 10, the reaction temperature is -10°C to 100°C, and the reaction time is 1 to 48 hours; Among them, R ¹ , R ² , R ³ , bridge chain and

All as described in claim 1. 5. the synthetic method of double Schiff base-cobalt complex according to claim 4 is characterized in that, described organic solvent is selected from chloroform, methylene dichloride, carbon tetrachloride, tetrahydrofuran (THF), 1,2-bis At least one of ethyl chloride, ether, methanol, ethanol, N,N-dimethylformamide and dimethyl sulfoxide. 6. a kind of synthetic method of double Schiff base-cobalt complex compound described in claim 2 is characterized in that, double Schiff base-cobalt complex compound described in claim 1 is mixed with Organic acid effect, the reaction molar ratio of double Schiff base-cobalt complex compound described in claim 1 and organic acid is 1: 2～10, and reaction temperature is 0～50 ℃, and the reaction time is 1～24 hours; Described organic acid is selected from acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3-nitrobenzenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, camphorsulfonic acid acid, p-nitrobenzoic acid and benzoic acid at least one. 7. the purposes of a kind of double Schiff base-cobalt complex described in claim 1 or 2, it is characterized in that, be used for the hydrolysis kinetic resolution reaction of the terminal epoxy compound of catalysis racemization, synthetically have optical activity Diol and epoxy compound; The structure of the racemic terminal epoxy compound is:

R wherein R is selected from C1-C20 alkyl groups, aryl groups or alkyl groups with ether, carboxylate, cyano and halogen functional groups at the end. 8. the purposes of double Schiff base-cobalt complex according to claim 7, is characterized in that, the terminal epoxy compound of racemization, organic solvent and double Schiff base-cobalt complex described in claim 1 Compound reacts with organic acid, adds water, reacts chiral epoxy and diol product; Wherein: the mol ratio of organic acid and double Schiff base-cobalt complex described in claim 1 is 2～20: 1, The mol ratio of the racemic terminal epoxy compound and the double Schiff base-cobalt complex described in claim 1 is 100000～100: 1, and the mol ratio of the racemic terminal epoxy compound and water is 1～10: 5. 9. the purposes of double Schiff base-cobalt complex according to claim 7, is characterized in that, described R is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl radical, isopentyl, chloromethyl, benzyloxymethyl or phenyl.

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