Photochiral diarylethene-based ligands and their photocontrolled asymmetric catalytic applications

Abstract

The application discloses a kind of photocontrol chiral ligand based on diarylethene, structural general formula is as shown in following formula:After the photocontrol chiral ligand based on diarylethene synthesized in the application and rhodium catalyst coordination, when catalyzing asymmetric carbon hydrogen amidation at room temperature, higher reaction yield and higher ee value can be obtained by using ligand in open loop state to catalyze, and lower reaction yield and lower ee value can be obtained by using ligand in light stable state to catalyze.The application makes up the deficiency that there is currently lack of photo-thermal bistable photocontrol catalyst in the field of photocontrol asymmetric catalysis, and widens the application of diarylethene in photocontrol asymmetric catalysis.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis methods, specifically, it relates to a class of photocontrolled chiral ligands based on diarylethene and their photocontrolled asymmetric catalytic applications. Background Technology

[0002] Light is a green, clean, and nearly inexhaustible energy source. Using light to control the reaction yield and enantioselectivity of asymmetric catalytic reactions is called photocontrolled asymmetric catalysis. Photocontrolled asymmetric catalysis is an emerging field in recent years, with few examples currently available. Most catalysts are based on stilbene (Ben L. Feringa et al. Science. 2011, 331, 1429-1432.) and azobenzene (Shinobu Takizawa et al. Org. Lett. 2022, 24, 14, 2670–2674.) molecules. Because these molecules generally have poor thermal stability and short half-lives after light exposure, they often lack the ability to perform photocontrolled catalytic reactions at high temperatures or even room temperature in dark environments.

[0003] Diarylethylene is an organic photochromic molecule with excellent properties. Its outstanding advantage lies in its photothermal bistable state, and its half-life after light exposure is typically several months or even years. Therefore, using diarylethylene for photocontrolled asymmetric catalysis can overcome the above-mentioned shortcomings. Although diarylethylene itself has potential axial chirality, most diarylethylene is in a spontaneous racemic state. Therefore, currently only a very few examples have achieved photocontrolled asymmetric catalysis by introducing chiral groups into diarylethylene (Neil R. Branda et al. Angew. Chem. Int. Ed. 2005, 44, 2019–2021.).

[0004] Recent studies have revealed that diarylethenes using benzodithiadiazole as an olefin bridge can achieve the separation of chiral diarylethene isomers by increasing the steric hindrance of the side chains. The chirality of these diarylethenes can be controlled by light. Utilizing the axial chirality of these diarylethenes to achieve photocontrolled asymmetric catalysis would broaden the molecular design of photocontrolled catalysis while ensuring the photothermal bistability of the catalyst, which is of great significance for solving the aforementioned problems. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a class of photo-controlled chiral ligands based on diarylethene. These ligands can achieve photocontrol of the yield and enantioselectivity of rhodium-catalyzed asymmetric carbohydramidation reactions, while also possessing excellent thermal stability, allowing for regulation at room temperature.

[0006] Another object of the present invention is to provide an application of the aforementioned diarylethene-based photocontrolled chiral ligand in the preparation of ligands for photocontrolled asymmetric catalytic reactions.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a class of photo-controlled chiral ligands based on diarylethene, with the following general structural formula:

[0009]

[0010] Wherein, X is selected from C1 to C10 alkyl groups, R1 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0011] R2 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0012] R3 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0013] R4 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy.

[0014] R5 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0015] Y is selected from C1-C10 alkyl groups. R6 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0016] R7 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0017] R8 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy;

[0018] R9 is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy.

[0019] R 10 It is selected from hydrogen, C1-C10 alkyl, and C1-C10 alkoxy.

[0020] More preferably, in the structure of the photocontrolled chiral ligand based on diarylethene:

[0021] X is selected from methyl, ethyl, n-propyl, R1 is selected from hydrogen, methyl, ethyl, methoxy, and ethoxy.

[0022] R2 is selected from hydrogen, methyl, ethyl, methoxy, and ethoxy.

[0023] R3 is selected from hydrogen, methyl, ethyl, methoxy, and ethoxy.

[0024] R4 is selected from hydrogen, methyl, ethyl, methoxy, and ethoxy.

[0025] R5 is selected from hydrogen, methyl, ethyl, methoxy, and ethoxy.

[0026] Y is selected from methyl, ethyl, n-propyl,

[0027] R6 is selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, and ethoxy.

[0028] R7 is selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, and ethoxy.

[0029] R8 is selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, and ethoxy.

[0030] R9 is selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, and ethoxy.

[0031] R 10 Selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, methoxy, and ethoxy.

[0032] Most preferably, the structure of the photocontrolled chiral ligand based on diarylethene is selected from one of the following structures:

[0033]

[0034] The chiral structure of the photocontrolled chiral ligand based on diarylethene is shown below:

[0035]

[0036] In a second aspect, the present invention provides the application of the aforementioned diarylethene-based photocontrolled chiral ligand in the preparation of ligands for photocontrolled asymmetric catalytic reactions or catalysts for photocontrolled asymmetric catalytic reactions (asymmetric catalysis after coordination of the chiral ligand with [CPRhCl2]2).

[0037] The photocontrolled asymmetric catalytic reaction is shown below, in which the photocontrolled chiral ligand based on diarylethene is used as the ligand, and photocontrolled asymmetric catalysis is performed after coordination with the rhodium catalyst [CP*RhCl2]2:

[0038]

[0039] By adopting the above technical solution, the present invention has the following advantages and beneficial effects:

[0040] The photocontrolled chiral ligand based on diarylethene synthesized in this invention, after coordination with a rhodium catalyst, exhibits higher reaction yields and higher ee values ​​when catalyzing asymmetric hydrocarbon amidation at room temperature using the ring-open ligand, while lower reaction yields and lower ee values ​​are obtained when using the photostable ligand. This invention addresses the current lack of photothermal bistable photocontrolled catalysts in the field of photocontrolled asymmetric catalysis, thus broadening the application of diarylethene in photocontrolled asymmetric catalysis.

[0041] The photo-controlled chiral ligands based on diarylene synthesized in this invention exhibit chiral photoresponse properties and good thermal stability.

[0042] The method for preparing the photocontrolled chiral ligand based on diarylene ethylene of the present invention is simple, the raw materials are readily available, and it can be used as a ligand or catalyst in photocontrolled asymmetric catalytic reactions, with a high product yield. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the hydrogen NMR spectrum of the organic ligand L1.

[0044] Figure 2 This is a schematic diagram of the hydrogen NMR spectrum of the organic ligand L2.

[0045] Figure 3 This is a schematic diagram of the hydrogen NMR spectrum of the organic ligand L3.

[0046] Figure 4 This is a schematic diagram of the hydrogen NMR spectrum of the organic ligand L4.

[0047] Figure 5 This is a schematic diagram of the 1H NMR spectrum of the product N-(1-(quinoline-8-yl)ethyl)benzamide.

[0048] Figure 6 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using the open-ring ligand L2.

[0049] Figure 7 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using the photo-stable ligand L2.

[0050] Figure 8 This is a schematic diagram of the chiral liquid phase analysis of the racemic product N-(1-(quinolin-8-yl)ethyl)benzamide obtained without ligand participation in the reaction.

[0051] Figure 9 This is a schematic diagram of the high-resolution mass spectrum of the organic ligand L1.

[0052] Figure 10 This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L2.

[0053] Figure 11This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L3.

[0054] Figure 12 This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L4.

[0055] Figure 13 This is a schematic diagram of the 1H NMR spectrum of the steady-state L2 at the catalytic concentration.

[0056] Figure 14 This is a schematic diagram showing the changes in the ultraviolet absorption spectrum of the organic ligand L2 under light irradiation.

[0057] Figure 15 This is a schematic diagram showing the circular dichroism spectrum changes of two isomers of the organic ligand L2 under illumination.

[0058] Figure 16 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of the organic ligand L2.

[0059] Figure 17 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of the organic ligand L2.

[0060] Figure 18 This is a schematic diagram of the thermal stability test of organic ligand L2 at 25℃.

[0061] Figure 19 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using the open-ring ligand L4.

[0062] Figure 20 This is a schematic diagram of the chiral liquid phase analysis of the product obtained by catalytic reaction using the photo-stable ligand L4.

[0063] Figure 21 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of the organic ligand L4.

[0064] Figure 22 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of the organic ligand L4.

[0065] Figure 23 This is a schematic diagram of the 1H NMR spectrum of the steady-state L2 at the catalytic concentration.

[0066] Figure 24 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of the organic ligand L1.

[0067] Figure 25 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of organic ligand L1.

[0068] Figure 26 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of the organic ligand L3.

[0069] Figure 27 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of the organic ligand L3. Detailed Implementation

[0070] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0071] Example 1

[0072] Preparation of diarylethene ligand L1:

[0073] Step 1, synthesis of intermediate compound 1:

[0074]

[0075] In a 250 mL three-necked flask, dibromobenzodithiadiazole (1 g, 2.84 mmol), benzothiophene 2-methyl-3-boronic acid (710 mg, 3.7 mmol), sodium carbonate (3.18 g, 30 mmol), water (15 mL), and tetrahydrofuran (54 mL) were added sequentially. Finally, Pd(PPh3)4 (77 mg, 0.067 mmol) was added, and the mixture was heated under reflux for 8 h under nitrogen protection. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:PE = 1:2, Rf = 0.5) to give 950 mg of compound 1, with a yield of 79.8%.

[0076] The second step is the synthesis of the intermediate ap-L1-CHO:

[0077]

[0078] In a 250 mL three-necked flask, compound 1 (600 mg, 1.43 mmol), compound 2 (800 mg, 4.35 mmol), sodium carbonate (4.24 g, 40 mmol), water (20 mL), and tetrahydrofuran (40 mL) were added sequentially. Finally, Pd(PPh3)4 (165 mg, 0.143 mmol) was added, and the mixture was heated under reflux for 8 h under nitrogen protection. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:PE = 1:1, Rf = 0.5) to give 450 mg of crude product, with a yield of 63.6%. All crude products were dissolved in 250 ml of tetrahydrofuran and irradiated with 365 nm UV light for 8 h. The solvent was then evaporated to dryness. 30 ml of ethyl acetate and 60 ml of n-hexane were added, and the mixture was sonicated in the dark for 1 h. The solid was collected by suction filtration and dissolved in 30 ml of dichloromethane. The solution was irradiated with yellow-green light greater than 490 nm until colorless. The solvent was then evaporated to dryness, yielding 250 mg of a white solid. Nuclear magnetic resonance chemical shift analysis confirmed that the product was the antiparallel form ap-L1-CHO, with a yield of 35%. ap-L1-CHO: 1 H NMR (400MHz, CDCl3, ppm): δ9.84 (s, 1H), 7.78 (d, 1H, J = 7.9Hz), 7.28 (t, 1H, J = 7.4Hz), 7.18 (t, 1H, J = 7.4Hz), 2.75 (s, 3H), 2.13 (s, 3H), 1.71 (s, 3H).

[0079] The third step is the synthesis of the ligand ap-L1.

[0080]

[0081] ap-L1-CHO (250 mg, 0.52 mmol) was dissolved in 20 mL of acetone, 2.5 mL of water was added, followed by 2-methyl-2-butene (0.6 mL, 7.29 mmol), 80% sodium chlorite (450 mg, 4 mmol), and sodium dihydrogen phosphate (210 mg, 1.74 mmol). The mixture was stirred overnight at room temperature. After the reaction was complete, 30 mL of water was added, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:MeOH = 30:1, Rf = 0.3) to obtain 230 mg of white solid, i.e., ap-L1, with a yield of 89%. Figure 1 This is a schematic diagram of the 1H NMR spectrum of the organic ligand L1. ap-L1: 1HNMR (400MHz, CD2Cl2, ppm): δ7.75 (d, 1H, J = 8.1Hz), 7.24 (t, 1H, J = 7.6Hz), 7.13 (t, 1H, J = 7 .6Hz),7.00(d,1H,J=8.1Hz),2.56(s,3H),2.14(s,3H),1.67(s,3H).HRMS-ESI:Theo.Mass for[MH] - :492.9916.found:492.9923. Figure 9 This is a schematic diagram of the high-resolution mass spectrum of the organic ligand L1.

[0082] Step 4: Chiral dissociation of ligand ap-L1

[0083]

[0084] ap-L1 was separated using a preparative liquid chromatography column (CHIRALPAK IC(IC00CD-TB016)). The mobile phase was dichloromethane / ethyl acetate / trifluoroacetic acid = (80 / 20 / 0.1)(V / V / V), the flow rate was 1 mL / min, the detection wavelength was 254 nm, and the temperature was 35 °C. A pair of enantiomers, M-L1 and p-L1, were obtained after separation.

[0085] Figure 24 This is a schematic diagram of chiral liquid chromatography analysis of the Peak1 isomer of the organic ligand L1, with an ee value of 99% for Peak1. Figure 25 This is a schematic diagram of chiral liquid chromatography analysis of the Peak2 isomer of organic ligand L1, with an ee value of 98% for Peak2.

[0086] Example 2

[0087] Preparation of diarylethylene ligand L2

[0088] Step 1: Synthesis of intermediate 3,5-dibromo-2-methyl-4-thiophenecarboxaldehyde:

[0089]

[0090] 2-Methyl-3-thiophenecarboxaldehyde (5.5 g, 43.6 mmol) was dissolved in 100 mL of acetic acid, and liquid bromine (4.5 mL, 87.8 mmol) was added. The reaction was carried out at 70 °C for 5 h. 100 mL of dichloromethane was added to the reaction solution. The organic phase was washed with water and saturated sodium sulfite solution, dried over anhydrous sodium sulfate, and the solvent was evaporated. The solution was separated by column chromatography (PE:EA = 20:1, Rf = 0.5) to give 6.75 g of yellow solid, with a yield of 54.6%.

[0091] The second step involves the synthesis of the intermediate 3-bromo-5-phenyl-2-methyl-4-thiophenecarboxaldehyde.

[0092]

[0093] 3,5-Dibromo-2-methyl-4-thiophenecarboxaldehyde (2.84 g, 10 mmol) was dissolved in 30 mL of tetrahydrofuran, and phenylboronic acid (1.22 g, 10 mmol), 25 mL of water, and anhydrous sodium carbonate (5 g, 47.2 mmol) were added. Finally, tetra(triphenylphosphine)palladium (115 mg, 0.1 mmol) was added. The reaction apparatus was refluxed under nitrogen protection for 5 h. After the reaction was completed, the aqueous phase was extracted with dichloromethane (30 mL × 3), and all organic phases were collected. After drying with anhydrous sodium sulfate, the solvent was evaporated, and the mixture was separated by column chromatography (PE:EA = 10:1, Rf = 0.5) to give 2.5 g of yellow liquid, with a yield of 90%.

[0094] The third step is the synthesis of the intermediate 5-phenyl-3-boronic acid pinacol ester-2-methyl-4-thiophenecarboxaldehyde.

[0095]

[0096] 2.5 g (8.9 mmol) of 3-bromo-5-phenyl-2-methyl-4-thiophenecarboxaldehyde was dissolved in 57 mL of 1,4-dioxane. Pinacol diborate (5.1 g, 20 mmol) and potassium acetate (4.9 g, 50 mmol) were added, followed by Pd(dppf)Cl2 (300 mg, 0.41 mmol). The reaction apparatus was refluxed under nitrogen protection for 12 h. After the reaction was complete, the solvent was evaporated, 100 mL of dichloromethane was added, and the mixture was washed with saturated brine. The organic phase was collected, dried over anhydrous sodium sulfate, and then evaporated again. Separation was performed by column chromatography (PE:EA = 4:1, Rf = 0.4) to obtain a yellow solid. Recrystallization from n-hexane yielded 3.2 g of a white solid, which, according to NMR, was a mixture of the product and pinacol diborate in a 1:1 ratio, with an actual yield of 62%.

[0097] Step 4: Synthesis of intermediate L2-CHO

[0098]

[0099] In a 250 mL three-necked flask, compound 1 (600 mg, 1.43 mmol), purified compound 3 (2.5 g, 4.35 mmol), sodium carbonate (4.24 g, 40 mmol), water (20 mL), and tetrahydrofuran (40 mL) were added sequentially. Finally, tetra(triphenylphosphine)palladium (165 mg, 0.143 mmol) was added, and the mixture was heated under nitrogen protection and refluxed for 8 h. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:PE = 1:1, Rf = 0.5) to give 550 mg of crude product, with a yield of 69.1%. The crude product was dissolved in 250 mL of tetrahydrofuran and irradiated with a 365 nm UV flashlight for 8 h. After the solvent was evaporated, the residue was dissolved in toluene and separated by column chromatography (toluene:DCM = 1:1, Rf = 0.2). The collected closed-ring product was irradiated with yellow-green light greater than 490 nm until colorless, and the solvent was evaporated to give 260 mg of a white solid. NMR spectroscopy confirmed it to be ap-L2-CHO, with a yield of 33.6%. ap-L2-CHO: 1 H NMR (400MHz, CDCl3, ppm): δ9.72 (s, 1H), 7.79 (d, 1H, J = 7.8Hz), 7.43-7.51 (m, 5H), 7.29 (t,1H,J=7.4Hz),7.2(t,1H,J=7.7Hz),7.08(d,1H,J=8.1Hz),2.19(s,3H),1.79(s,3H).

[0100] Step 4: Chiral separation of L2-CHO

[0101]

[0102] ap-L2-CHO was separated using a preparative liquid chromatography column (CHIRALPAK IH(IH00CD-VK010)). The mobile phase was Hexane / EtOH / DEA = 70 / 30 / 0.1 (V / V / V), the flow rate was 1 mL / min, the detection wavelength was 254 nm, and the temperature was 35 °C. A pair of enantiomers, M-L2-CHO and p-L2-CHO, were obtained after separation.

[0103] Step 5: Synthesis of ligand L2

[0104]

[0105] 100 mg of the isolated peak1 or peak2 (i.e., M-L2-CHO or P-L2-CHO) was dissolved in 10 ml of acetone, and 1 ml of water was added. Then, 0.4 ml of 2-methyl-2-butene (4.86 mmol), sodium chlorite (270 mg, 3 mmol), and sodium dihydrogen phosphate (100 mg, 0.83 mmol) were added. The reaction mixture was stirred overnight at room temperature. After the reaction was complete, 30 ml of water was added, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 ml × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:MeOH = 30:1, Rf = 0.4) to give 90 mg of a white solid, with a yield of 87.1%. The obtained compound was confirmed as ligand L2 by NMR and mass spectrometry. Figure 2 This is a schematic diagram of the 1H NMR spectrum of the organic ligand L2. L2: 1 H NMR (400MHz, CD2Cl2, ppm): δ7.77(d,1H,J=8.1Hz),7.28-7.39(m,5H),7.25(t,1H,J=7.7Hz),7 .15(t,1H,J=7.9Hz),7.02(d,1H,J=8Hz),2.22(s,3H),1.8(s,3H).HRMS-ESI(m / z):Theo.Mass for[MH] - :555.0072.found:555.0082. Figure 10 This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L2. Figure 16 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of the organic ligand L2. As shown in the figure, the ee value of Peak1 is 98%. Figure 17 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of the organic ligand L2. As shown in the figure, the ee value of Peak2 is 98%.

[0106] Example 3

[0107] Preparation of diarylethylene ligand L3

[0108] Step 1: Synthesis of the intermediate 3-bromo-5-(3,5-di-tert-butyl-4-methoxy)-2-methyl-4-thiophenecarboxaldehyde:

[0109]

[0110] 3,5-Dibromo-2-methyl-4-thiophenecarboxaldehyde (5 g, 17.6 mmol) was dissolved in 30 mL of tetrahydrofuran, and 3,5-di-tert-butyl-4-methoxyboronic acid (5 g, 18.9 mmol), 25 mL of water, and anhydrous sodium carbonate (5 g, 47.2 mmol) were added. Finally, tetrakis(triphenylphosphine)palladium (200 mg, 0.173 mmol) was added. The reaction apparatus was refluxed under nitrogen protection for 5 h. After the reaction was completed, the aqueous phase was extracted with dichloromethane (30 mL × 3), and all organic phases were collected. After drying with anhydrous sodium sulfate, the solvent was evaporated, and the mixture was separated by column chromatography (PE:DCM = 1:2, Rf = 0.5) to give 6.2 g of yellow liquid, with a yield of 83.2%.

[0111] The second step involves the intermediate 5-(3,5-di-tert-butyl-4-methoxy)-3-boronic acid pinacol ester-2-methyl-4-thiophene carboxaldehyde.

[0112]

[0113] 6.2 g (14.6 mmol) of 3-bromo-5-(3,5-di-tert-butyl-4-methoxy)-2-methyl-4-thiophenecarboxaldehyde was dissolved in 100 mL of 1,4-dioxane. Pinacol diborate (9 g, 35.3 mmol) and potassium acetate (4.9 g, 50 mmol) were added, followed by Pd(dppf)Cl2 (300 mg, 0.41 mmol). The reaction apparatus was refluxed under nitrogen protection for 12 h. After the reaction was complete, the solvent was evaporated, 100 mL of dichloromethane was added, and the mixture was washed with saturated brine. The organic phase was collected, dried over anhydrous sodium sulfate, and then evaporated again. Separation was performed by column chromatography (PE:EA = 2:1, Rf = 0.4) to obtain a yellow solid. Recrystallization from n-hexane yielded 6.2 g of a white solid, which, according to NMR, was a mixture of the product and pinacol diborate in a 1:1.5 ratio, with an actual yield of 50%.

[0114] The third step is the synthesis of the intermediate L3-CHO.

[0115]

[0116] In a 250 mL three-necked flask, compound 1 (600 mg, 1.43 mmol), purified compound 4 (3.6 g, 4.29 mmol), sodium carbonate (4.24 g, 40 mmol), 20 mL of water, and 40 mL of tetrahydrofuran were added sequentially. Finally, tetra(triphenylphosphine)palladium (137 mg, 0.119 mmol) was added, and the mixture was heated under nitrogen protection and refluxed for 8 h. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:PE = 1:1, Rf = 0.5) to give 550 mg of crude product, with a yield of 65.5%. The crude product was dissolved in 250 mL of tetrahydrofuran and irradiated with a 365 nm UV flashlight for 8 h. After the solvent was evaporated, the residue was dissolved in toluene and separated by column chromatography (toluene:DCM = 2:1, Rf = 0.3). The collected closed-ring product was irradiated with yellow-green light greater than 490 nm until colorless, and the solvent was evaporated to give 330 mg of a white solid. The solid was confirmed as ap-L3-CHO by NMR chemical shift, with a yield of 33.8%. ap-L3-CHO: 1 H NMR (400MHz, CDCl3, ppm): δ9.66 (s, 1H), 7.78 (d, 1H, J = 8Hz), 7.27 (t, 1H, J = 7.9Hz), 7.25 (s, 2H), 7.18(t,1H,J=7.6Hz),7.07(d,1H,J=7.8Hz),3.73(s,3H),2.2(s,3H),1.84(s,3H),1.45(s,18H).

[0117] Step 4: Chiral separation of L3-CHO

[0118]

[0119] ap-L3-CHO was separated using a preparative liquid chromatography column (CHIRALPAK IE-3(IE30CE-XB011)). The mobile phase was Hexane / DCM = 50 / 50 (V / V), the flow rate was 1 mL / min, the detection wavelength was 254 nm, and the temperature was 35 °C. A pair of enantiomers, M-L3-CHO and p-L3-CHO, were obtained after separation.

[0120] Step 5: Synthesis of ligand L3

[0121]

[0122] 130 mg of the isolated peak1 or peak2 (i.e., M-L3-CHO or P-L3-CHO) was dissolved in 10 ml of acetone, and 1 ml of water was added. Then, 0.4 ml of 2-methyl-2-butene (4.86 mmol), sodium chlorite (270 mg, 3 mmol), and sodium dihydrogen phosphate (100 mg, 0.83 mmol) were added. The reaction mixture was stirred overnight at room temperature. After the reaction was complete, 30 ml of water was added to the reaction solution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 ml × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:MeOH = 50:1, Rf = 0.3) to give 110 mg of a white solid, with a yield of 83%. The obtained compound was confirmed as ligand L3 by NMR and mass spectrometry. Figure 3 This is a schematic diagram of the 1H NMR spectrum of the organic ligand L3. L3: 1 H NMR (400MHz, CD2Cl2, ppm): δ7.75 (d, 1H, J = 7.9Hz), 7.23 (t, 1H, J = 7.6Hz), 7.1-7.15 (m, 3H), 6.99 ( d,1H,J=8.1Hz),3.64(s,3H),2.19(s,3H),1.84(s,3H),1.33(s,18H).HRMS-ESI(m / z):Theo.Mass for[MH] - :697.1430.found:697.1447. Figure 11 This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L3. Figure 26 This is a schematic diagram of chiral liquid chromatography analysis of the Peak1 isomer of the organic ligand L3, with an ee value of 99% for Peak1. Figure 27 This is a schematic diagram of chiral liquid chromatography analysis of the Peak2 isomer of the organic ligand L3, with an ee value of 98% for Peak2.

[0123] Example 4

[0124] Preparation of diarylethylene ligand L4

[0125] The first step is the synthesis of intermediate compound 5.

[0126]

[0127] In a 250 mL three-necked flask, dibromobenzodithiadiazole (1 g, 2.84 mmol), benzothiophene 2-benzyl-3-boronic acid (990 mg, 3.7 mmol), sodium carbonate (3.18 g, 30 mmol), water (15 mL), and tetrahydrofuran (54 mL) were added sequentially. Finally, Pd(PPh3)4 (77 mg, 0.067 mmol) was added, and the mixture was heated under reflux for 8 h under nitrogen protection. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:PE = 1:2, Rf = 0.6) to give 985 mg of compound 5, with a yield of 70%.

[0128] The second step is the synthesis of the intermediate L4-CHO.

[0129]

[0130] In a 250 mL three-necked flask, compound 5 (800 mg, 1.61 mmol), purified compound 3 (3 g, 5.22 mmol), sodium carbonate (6.36 g, 60 mmol), water (30 mL), and tetrahydrofuran (60 mL) were added sequentially. Finally, tetra(triphenylphosphine)palladium (192 mg, 0.166 mmol) was added, and the mixture was heated under nitrogen protection and refluxed for 8 h. After the reaction was complete, the solution was poured into 20 mL of water, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (toluene:DCM = 1:1, Rf = 0.4) to give 550 mg of crude product, with a yield of 55.4%. The crude product was dissolved in 250 mL of tetrahydrofuran and irradiated with a 365 nm UV flashlight for 8 h. After the solvent was evaporated, the residue was dissolved in toluene and separated by column chromatography (toluene:DCM = 1:1, Rf = 0.2). The collected closed-ring compound was irradiated with yellow-green light greater than 490 nm until colorless, and the solvent was evaporated to give 360 ​​mg of a white solid, with a yield of 36.2%. The obtained compound was identified as ap-L4-CHO by NMR shift. 1 H NMR (400MHz, CDCl3, ppm): δ9.57 (s, 1H), 7.77 (d, 1H, J = 8Hz), 7.38-7.47 (m, 3H), 7.3 ( t,1H,J=7.5Hz),7.07-7.27(m,7H),6.85(m,2H),3.98(d,2H,J=1.6Hz),1.86(s,3H).

[0131] Step 3: Chiral separation of L4-CHO

[0132]

[0133] 360 mg of ap-L4-CHO was separated using a preparative liquid chromatography column (CHIRALPAK IC(IC00CE-WF029)). The mobile phase was Hexane / DCM = 55 / 45 (V / V), the flow rate was 1 mL / min, the detection wavelength was 254 nm, and the temperature was 35 °C. A pair of enantiomers, M-L4-CHO and p-L4-CHO, were obtained after separation.

[0134] The second step is the synthesis of ligand L4.

[0135]

[0136] 150 mg of the isolated peak1 or peak2 (i.e., M-L4-CHO or P-L4-CHO) was dissolved in 10 ml of acetone, and 1 ml of water was added. Then, 0.4 ml of 2-methyl-2-butene (4.86 mmol), sodium chlorite (270 mg, 3 mmol), and sodium dihydrogen phosphate (100 mg, 0.83 mmol) were added. The reaction mixture was stirred overnight at room temperature. After the reaction was complete, 30 ml of water was added, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 ml × 3). All organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was evaporated. The mixture was then separated by column chromatography (DCM:MeOH = 30:1, Rf = 0.5) to obtain 130 mg of a white solid, with a yield of 84.5%. The obtained compound was confirmed as ligand L4 by NMR and mass spectrometry. Figure 4 This is a schematic diagram of the 1H NMR spectrum of the organic ligand L4. L4: 1 H NMR (400MHz, CD2Cl2, ppm): δ7.75 (d, 1H, J = 8.1Hz), 7.25-7.36 (m, 4H), 7.16-7.22 (m, 3H), 7.06-7.1 2(m,4H),6.86(m,2H),4.07(dd,2H,J1=56Hz,J2=16.4Hz),1.76(s,3H).HRMS-ESI(m / z):Theo.Mass for[MH]-:631.0385.found:631.0423. Figure 12 This is a schematic diagram of the high-resolution mass spectrometry of the organic ligand L4. Figure 21 This is a schematic diagram of chiral liquid phase analysis of the Peak1 isomer of organic ligand L4. As can be seen from the figure, the ee value of Peak1 is 90%. Figure 22 This is a schematic diagram of chiral liquid phase analysis of the Peak2 isomer of the organic ligand L4. As shown in the figure, the ee value of Peak2 is 99%.

[0137] Example 5

[0138] Organic ligand L2 photoresponse performance test

[0139] The organic ligand L2 obtained in Example 2 was dissolved in analytical grade tetrahydrofuran to prepare a solution of 4 × 10⁻⁶ ppm. -5 Take 10 ml of the solution, transfer 2 ml to an optical quartz glass cuvette, and test the change in its absorption spectrum under ultraviolet light. Figure 14 This is a schematic diagram of the ultraviolet absorption spectrum change of the organic ligand L2 under light irradiation. Under 313nm ultraviolet light irradiation, the solution changes from colorless to red, and new absorption peaks appear at 360nm, 400nm, and 520nm in the absorption spectrum, while the absorption at 290nm decreases. This process proves that L2 gradually changes from an open-ring state to a closed-ring state, and L2 has photoresponsive properties.

[0140] Example 6

[0141] Organic ligand L2 chiral photoresponse performance test

[0142] Take the ligand L2 (peak1 or peak2, corresponding to M-L2 or P-L2) obtained in Example 2, dissolve it in analytical grade tetrahydrofuran, and prepare a solution of 4×10 -5 Take 10 ml of solution, transfer 2 ml to an optical quartz glass cuvette, and test the changes in the circular dichroism spectrum of the two solutions under ultraviolet light. Figure 15 This is a schematic diagram of the circular dichroism spectral changes of two isomers of the organic ligand L2 under illumination. Taking peak1 as an example, under 313nm ultraviolet light, the circular dichroism absorption of peak1 solution is enhanced in the 280-600nm range, proving that there is a change in chiral signal from the open-ring form to the closed-ring form of the organic ligand L2.

[0143] Example 7

[0144] L2 photosteady-state thermal stability test of organic ligands

[0145] The tetrahydrofuran solution prepared in Example 5 was placed in an optical quartz glass cuvette and irradiated with 313nm ultraviolet light for 10 minutes until it reached the photosteady state. The absorbance at 522nm was measured every 24 hours. The thermal stability of the ligand L2 photosteady state was confirmed by the degree of decrease in ultraviolet absorption. Figure 18 This is a schematic diagram of the thermal stability test of organic ligand L2 at 25℃. After being placed at room temperature for 96 hours, the absorbance at 522nm did not decrease significantly, which means that the closed ring basically did not undergo transformation, proving that the photostable state of organic ligand L2 has excellent thermal stability at room temperature.

[0146] Example 8

[0147] Ligand-free hydrocarbon amidation:

[0148]

[0149] In a glove box, silver hexafluoroantimonate (2.8 mg, 0.008 mmol), [Cp*RhCl2]2 (1.2 mg, 0.002 mmol), reactant A (7.9 mg, 0.05 mmol), and reactant B (9.8 mg, 0.06 mmol) were weighed into a brown vial. The reaction was carried out at room temperature in the dark for 12 h. After the reaction was completed, the yield was calculated by 1H NMR using 1,1,2,2-tetrabromoethane as an internal standard. The yield was 15%. The product was separated by large plate separation (PE:EA = 4:1, Rf = 0.3), and the ee value was obtained by chiral high performance liquid chromatography. Figure 5 This is a schematic diagram of the 1H NMR spectrum of the product N-(1-(quinoline-8-yl)ethyl)benzamide. N-(1-(quinoline-8-yl)ethyl)benzamide: 1 H NMR (400MHz, CDCl3, ppm): δ8.95 (dd, 1H, J1 = 4.3Hz, J2 = 1.7Hz), 8.2 (dd, 1H, J1 = 8.3Hz, J2 = 1.8Hz), 7.79-7.85 (m ,2H),7.72-7.77(m,1H),7.66-7.71(m,1H),7.36-7.52(m,5H),5.79-5.89(m,1H),1.74-1.78(d,3H,J=6.9Hz). Figure 8 This is a schematic diagram of the chiral liquid phase analysis of the racemic product N-(1-(quinolin-8-yl)ethyl)benzamide obtained without ligand participation in the reaction. The results demonstrate that the racemic product was obtained in the control experiment without the addition of ligands.

[0150] Example 9

[0151] Photo-controlled asymmetric hydrocarbon activation reaction using compound L2 as a ligand:

[0152]

[0153] In a glove box, weigh silver hexafluoroantimonate (2.8 mg, 0.008 mmol), [Cp*RhCl2]2 (1.2 mg, 0.002 mmol), reactant A (7.9 mg, 0.05 mmol), and reactant B (9.8 mg, 0.06 mmol) into two separate brown vials. Also, weigh ligand compound L2 (peak1 or peak2, corresponding to M-L2 or P-L2) into two separate transparent vials (2.3 mg, 0.008 mmol, 0.008 mmol, 0.008 mmol, 0.002 ... mg, 0.004 mmol), added 0.5 ml of ultra-dry dichloromethane, took one of the transparent vials and irradiated it with a 365 nm UV flashlight for 10 min until it reached photostable state, then added it to two brown vials. The open-ring ligand was numbered 1, and the photostable ligand was numbered 2. The reaction flasks were reacted at room temperature in the dark for 12 h. After the reaction, the yield was calculated by 1H NMR using 1,1,2,2-tetrabromoethane as an internal standard. The yield of reaction 1 was 67%, and the yield of reaction 2 was 40%. The products were separated by large plate separation (PE:EA = 4:1, Rf = 0.3), and the ee value was obtained by chiral high performance liquid chromatography. The yield of reaction 1 using the open-ring ligand L2 (peak 1) was 42% ( Figure 6 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using open-ring ligand L2. The photo-stable ligand L2 (peak 1) was used at a concentration of 4% ( ). Figure 7 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using the light-stable ligand L2.

[0154] Figure 13 This is a schematic diagram of the 1H NMR spectrum of the photosteady-state L2 at the catalytic concentration. Comparison of the integrated NMR areas reveals that the ratio of open-ring to closed-ring components at this concentration is 40:60.

[0155] Example 10

[0156] Photocontrolled asymmetric hydrocarbon activation reaction using organic ligand L4 as the ligand

[0157]

[0158] In a glove box, silver hexafluoroantimonate (2.8 mg, 0.008 mmol), [Cp*RhCl2]2 (1.2 mg, 0.002 mmol), reactant A (7.9 mg, 0.05 mmol), and reactant B (9.8 mg, 0.06 mmol) were weighed into two separate brown vials. In another two transparent vials, ligand compound L4 (2.5 mg, 0.004 mmol) was weighed into each vial. 0.5 ml of ultra-dry dichloromethane was added. One of the transparent vials was irradiated with a 365 nm UV flashlight for 10 min until it reached a photostable state. This irradiation was then added to the two brown vials. The open-ring ligand was numbered 3, and the photostable ligand was numbered 4. The reaction flasks were reacted at room temperature in the dark for 12 h. After the reaction, the yield was calculated using 1,1,2,2-tetrabromoethane as an internal standard and 1H NMR spectroscopy. The yield of reaction 3 was 68%, and the yield of reaction 4 was 50%. The product was separated by large plate separation (PE:EA = 4:1, Rf = 0.3), and the ee value was obtained by chiral high performance liquid chromatography analysis. The ee value of the open-ring ligand L4 (peak 1) was 46%. Figure 19 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using open-ring ligand L4. The percentage of peak 2 (of the photostable ligand L4 (peak 1)) is 0%. Figure 20 This is a schematic diagram of chiral liquid phase analysis of the product obtained by catalytic reaction using the photostable ligand L4.

[0159] Figure 23 This is a schematic diagram of the 1H NMR spectrum of the photosteady-state L2 at the catalytic concentration. Comparison of the integrated NMR areas reveals that the ratio of open-ring to closed-ring components at this concentration is 56:44.

[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A class of photo-controlled chiral ligands based on diarylethene, characterized in that, The structure of the photocontrolled chiral ligand based on diarylethene is selected from one of the following structures: 。 2. The photocontrolled chiral ligand based on diarylethene according to claim 1, characterized in that, The chiral structure of the photocontrolled chiral ligand based on diarylethene is shown below: 。 3. The application of the photocontrolled chiral ligand based on diarylethene as described in claim 1 in photocontrolled asymmetric catalytic reactions, characterized in that, The light-controlled asymmetric catalytic reaction is shown below: 。

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