Photocatalyst based on tropolone skeleton as well as synthesis method and application of photocatalyst

Abstract

The invention provides a photocatalyst based on a tropolone skeleton, the structural formula of the photocatalyst is shown in the specification, M is selected from one of H, Na and K, and R1 is one of H and aryl. The photocatalyst can be used for a Heck coupling reaction and a hydrogenation difluoroalkylation reaction. The prepared photocatalyst based on the tropolone skeleton can be separated through common separation operations such as extraction and suction filtration, the property is stable, raw materials are easy to obtain, a good foundation is laid for wide application of the photocatalyst in the industry, and the photocatalyst has important commercial value and industrial prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of organic photocatalysts, and particularly relates to a photocatalyst based on a tropolone skeleton, a synthesis method and an application thereof. Background Art

[0002] Tropolone (also known as tropolone) and its derivatives are widely found in natural products. In 1945, Devon first proposed the structure of tropolone based on tropitanic acid, a metabolite of Penicillium fungi, and colchicine, an alkaloid of the Liliaceae family, and considered them to be tropolone derivatives.

[0003]

[0004] Historically, most studies on tropolone and its derivatives have focused on their biological activities, such as antibacterial activity, insecticide and acaricide activity (see: Trust TJ, Bartlett KH, Antibacterial activity of tropilidine and tropone. Antimicrob. Agents Chemother. 1975.8.381-383.).

[0005] In contrast, research on its photochemical activity is limited. In 1972, Barrow and Mills, along with other groups, investigated the structure of tropolone, finding it to have a non-planar, bent structure and suggesting poor interactions between p-orbitals. In 1999, Mori and Ujiie's groups reported that some tropolone derivatives possess large dipole moments and rigid planar structures, potentially serving as core components of liquid crystals. In 2003, Yuki's research group successfully obtained a conjugated polymer containing a benzotropone structure in the main chain. Through ultraviolet spectroscopy, it was found that the photophysical properties of the tropone-containing conjugated polymer were strongly dependent on the tropone structure (see: Manabu Takemoto et al. Appearance of the Induced Smectic APhase in the Binary System between Two Troponoid Twins with the Opposite Dipole Moment. Chem. Lett., 11, 1177 (1999) Y. Yuki et al. Acid-doping to Tropone-containing Conjugated Polymer. Chem. Lett., 32, 552 (2003)).

[0006]

[0007] In recent years, phenolic compounds have attracted great interest and been widely explored in the field of photocatalysis due to their easy availability, ease of regulation, and the strong reducing ability of their anions. In 2018, Hasegawa used benzimidazolium naphthoxide betaine to achieve a photocatalytic desulfonylation cycle (see: Hasegawa, E. et al. Benzimidazolium Naphthoxide betaine is a visible light promoted organic photoredox catalyst. J. Org. Chem. 83, 3921-3927.). In 2019, Koing used 9-anthrone derivatives to achieve the catalytic reduction of aryl chlorides (see: Konig, B. et al. Utilizing excited-state organic anions for photoredox catalysis: activation of (hetero)aryl chlorides by visible light-absorbing 9-anthrolate anions. Faraday Discuss. 215, 364-378.). In the same year, Xia used 2,4,6-substituted phenolates to activate aryl halides to achieve oxyarylation of olefins (see: Xia, C. et al. Intermolecular oxyarylation of olefins with arylhalides and TEMPOH catalyzed by thephenolate anion undervisible light. Chem. Sci. 11, 6996--7002.). In 2022, Wenger used perylene diimide anions to achieve activation of aryl halides (see: OS Wenger. et al. Photophysics of Perylene Diimide Dianions and Their Application in Photoredox Catalysis. Angew. Chem. Int. Ed. 2022, 61, e202110491.).In addition, there are the benzofuran skeleton reported by Melchiorre (see: Melchiorre, P. et al. Photochemical organocatalytic synthesis of thioethers from aryl chlorides and alcohols. J. Am. Chem. Soc. 146, 2907-2912.), and the o-phosphinophenol and binaphthol skeletons reported by Shang's group (Shang, R. et al. Photocatalytic defluoroalkylation and hydrodefluorination of trifluoromethyls using o-phosphinophenolate. Nat. Commun. 13, 354. BINOLates as potent reducing photocatalysts for inert bond activation and reduction of unsaturated systems. Chem. 11, 1-12.). It can be seen that with continuous exploration, more and more phenolic photocatalysts are being gradually discovered.

[0008]

[0009] However, compared to reducing organic photocatalysts such as thiols or amines, phenolic structures have two problems. First, the higher electronegativity of the oxygen atom leads to its relatively weak reducing ability. Second, the phenolic oxygen radicals formed after electron transfer have high reactivity, making catalyst turnover difficult. By modifying the structure of phenolic compounds, it is possible to balance their redox potential, the kinetics of charge separation in the excited state, and the stability of oxygen radicals in the oxidized form. Therefore, the development of new phenolic skeletons is crucial for the development of related organic photocatalysts. Tropolone has an unusual non-benzene aromatic structure, which has not yet been developed as a photocatalyst, giving it considerable application prospects. Summary of the Invention

[0010] In view of the above technical problems, the present invention provides a photocatalyst based on a tropolone skeleton in a first aspect; in a second aspect, the present invention provides a method for preparing the above photocatalyst; in a third aspect, the present invention further provides a specific application of the above photocatalyst.

[0011] In the first aspect, the present invention provides a photocatalyst based on a tropolone skeleton, the structural formula of the photocatalyst is Wherein, M is selected from one of H, Na and K, and R1 is one of H and aryl. The photocatalyst has a skeleton of tropolone, wherein the phenolic group can be a hydroxyl structure or an oxygen anion structure, both of which have photocatalytic ability.

[0012] Preferably, the aryl is selected from It can be seen that the R1 substituent group of tropolone can be selected from common aryl substituent groups, and the aryl group can further carry various substituents, both electron-withdrawing substituents and electron-donating substituents.

[0013] In another aspect, the present application provides a synthesis method of the above-mentioned photocatalyst, comprising the following steps:

[0014] Step 1: In an inert gas atmosphere, 5-bromo-2-hydroxycyclohepta-2,4,6-triene-1-ketone, aryl-substituted boronic acid, palladium catalyst and base are placed in a reaction container, a solvent is added to dissolve the reactants, heated to a certain temperature and maintained for a certain time.

[0015] Step 2: After the reaction is completed, the reaction is cooled to room temperature, and the photocatalyst is obtained after separation.

[0016]

[0017] It can be seen that when the R1 substituent group is aryl, the corresponding aryl-substituted boronic acid can be selected to react with 5-bromotropolone to generate the photocatalyst based on the tropolone skeleton according to the present application.

[0018] Preferably, the base is one or more of sodium carbonate, potassium carbonate, sodium tert-butoxide and potassium tert-butoxide.

[0019] In another aspect, on the basis of the structure and synthesis method of the above-mentioned photocatalyst provided by the present application, the present application further provides specific applications of the above-mentioned photocatalyst in organic photocatalytic synthesis. The photocatalyst provided by the present application can activate the carbon-halogen bond of the haloalkyl group, so that the haloalkyl group and the aryl olefin undergo Heck coupling reaction.

[0020]

[0021] The specific reaction formula is shown above. Under an inert atmosphere, an aryl olefin, an alkyl bromide, a base, a photocatalyst based on a tropolone skeleton, and a solvent are added to a reaction vessel and stirred overnight under blue light irradiation. During the reaction, the aryl olefin and the alkyl bromide undergo a Heck coupling reaction, and after separation, a coupling product of the aryl olefin and the alkyl is obtained, wherein Ar1 and Ar2 are both aryl groups; R2 is an alkyl group, and X is a halogen, which can be one of chlorine, bromine, and iodine. It will be understood by those skilled in the art that the above-mentioned aryl group can also have some common substituents, such as alkyl, alkoxy, trifluoromethyl, etc., wherein the alkyl group represented by R2 can also have some other structures, such as alkoxy, ester, and carboxyl groups, etc., which means that the halogen X is directly connected to the saturated carbon atom in R2.

[0022] On the other hand, the present invention further provides a specific application of the above-mentioned photocatalyst in organic photocatalytic synthesis. The photocatalyst provided by the present invention can activate alkyl NHPI esters for decarboxylation, so that the alkyl NHPI esters undergo Heck coupling reaction with aromatic olefins.

[0023]

[0024] The specific reaction formula is shown above. Under an inert atmosphere, an aryl olefin, an alkyl NHPI ester, a tropolone-based photocatalyst, potassium trifluoroacetate, and a solvent are added to a reaction vessel. The mixture is stirred overnight under blue light irradiation. During the reaction, the alkyl NHPI ester loses its carboxyl group, and the aryl olefin and the alkyl NHPI ester undergo a Heck coupling reaction. After separation, the coupling product of the aryl olefin and the alkyl group is obtained. Ar3 and Ar4 are both aryl groups; R3 is an alkyl group. Those skilled in the art will appreciate that the aryl groups can also have common substituents, such as alkyl, alkoxy, and trifluoromethyl groups. The alkyl group represented by R3 can also have other structures, such as alkoxy, ester, and carboxyl groups. This means that the carbonyl carbon atom in the NHPI ester is directly connected to the saturated carbon atom in R3.

[0025] On the other hand, the present invention further provides a specific application of the above-mentioned photocatalyst in organic photocatalytic synthesis. The photocatalyst provided by the present invention can activate the carbon-fluorine bond of trifluoromethyl aromatic hydrocarbons, so that trifluoromethyl aromatic hydrocarbons undergo a hydrogenation difluoroalkylation reaction with aromatic olefins.

[0026]

[0027] The specific reaction formula is shown above, under an inert atmosphere, an aryl alkene, a trifluoromethyl aromatic hydrocarbon, a base, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole, a photocatalyst based on the tropone skeleton, and a solvent are added to a reaction vessel, and stirred under blue light irradiation overnight. During the reaction, the C-F bond of the trifluoromethyl aromatic hydrocarbon is activated, and the aryl alkene and the trifluoromethyl aromatic hydrocarbon undergo a hydrodifluoroalkylation reaction. After separation, a hydrodifluoroalkylation product is obtained. Among them, Ar5 and Ar7 are aryl groups, and those skilled in the art can understand that the aryl group can also have some common substituents, such as alkyl, alkoxy, trifluoromethyl, etc.; Ar6 can be selected from one of H, alkyl and aryl, and those skilled in the art can understand that when Ar6 is alkyl, the alkyl group can also have some other structures, such as alkoxy, ester and carboxyl, etc., which means that C=C is directly connected to the saturated C atom in Ar6; when Ar6 is aryl, and those skilled in the art can understand that the aryl group can also have some common substituents, such as alkyl, alkoxy, trifluoromethyl, etc. The hydrodifluoroalkylation reaction refers to the fact that after the reaction is completed, the C-F bond on the aryl group is broken, and coupling occurs with the aryl alkene, and hydrogenation occurs on the C=C double bond of the aryl alkene.

[0028] The beneficial technical effects of the present application are that an organic photocatalyst based on the tropone skeleton is developed for the first time, which is used as a reductive photocatalyst in organic photochemical synthesis, and the synthesis method and specific application of the photocatalyst are further developed. Secondly, the photocatalysis disclosed in the present application avoids using the noble metal catalyst commonly used in Heck coupling reaction, which can avoid the pollution caused by the noble metal catalyst in the subsequent separation process. In addition, the photochemical catalyst based on the tropone skeleton provided by the present application can be separated by common separation operations such as extraction and filtration, and has stable properties and easy-to-obtain raw materials, which lays a good foundation for its wide application in industry, and has important commercial value and industrial prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figures 1 and 2 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product prepared in Example 1 are shown in Figures 1 and 2, respectively.

[0030] Figures 3 and 4 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product prepared in Example 2 are shown in Figures 3 and 4, respectively.

[0031] Figures 5 and 6 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product prepared in Example 3 are shown in Figures 5 and 6, respectively.

[0032] Figures 7 and 8 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product prepared in Application Example 1 are shown in Figures 7 and 8, respectively.

[0033] Figures 9 and 10 They are respectively the hydrogen and carbon nuclear magnetic resonance spectra of the target product prepared in Application Example 2.

[0034] Figures 11 to 13 They are respectively the hydrogen nuclear magnetic resonance spectrum, carbon spectrum and fluorine spectrum of the target product prepared in Application Example 3. DETAILED DESCRIPTION

[0035] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0036] Example 1

[0037] Preparation of sodium 7-oxocyclohepta-1,3,5-triene-1-olate, the structural formula of which is The specific preparation process includes the following steps: 2-hydroxycyclohepta-2,4,6-triene-1-one (20 mmol) (purchased from Anhui Zesheng Technology Co., Ltd.) and sodium tert-butoxide (22 mmol) (purchased from Shanghai Adamas Reagent Co., Ltd.) are dissolved in acetonitrile solution (10 mL) (purchased from Shanghai Adamas Reagent Co., Ltd.) and stirred at room temperature for 3 hours. After the reaction is completed, the solid is filtered, dried, and spin-dried to obtain the solid product, sodium 7-oxocyclohepta-1,3,5-triene-1-olate, in a yield of 99%. Figure 1-2 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product are displayed, and the above spectra can confirm that the target product has been successfully prepared.

[0038] Example 2

[0039] Preparation of the compound 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-ol sodium, the structural formula of which is The specific preparation process includes the following steps: 5-bromo-2-hydroxycyclohepta-2,4,6-triene-1-one (10 mmol), 4-dimethylaminophenyl borate (15 mmol) (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), tetrakistriphenylphosphine palladium (0.4 mmol) (purchased from Anhui Zesheng Technology Co., Ltd.), and sodium carbonate (45 mmol) (purchased from Anhui Zesheng Technology Co., Ltd.) are dissolved in a 5:1 mixture of tetrahydrofuran and water (10 mL), heated to 100°C, and stirred for 24 hours. After the reaction is completed, the solid is filtered, dried, and spin-dried to obtain the solid product, sodium 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, in a yield of 96%. Figure 3-4 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product are displayed, and the above spectra can confirm that the target product has been successfully prepared.

[0040] Example 3

[0041] The specific steps are as in Example 2, except that (4-morpholinophenyl)boric acid is used instead of 4-dimethylaminophenyl borate in Step 1, and the obtained product is acidified with hydrochloric acid overnight. The final product is 2-hydroxy-5-(4-morpholinophenyl)cyclohepta-2,4,6-triene-1-one, and the specific chemical formula is: The yield was 70%. Figure 5-6 The nuclear magnetic resonance hydrogen spectrum and carbon spectrum of the target product are displayed, and the above spectra can confirm that the target product has been successfully prepared.

[0042] Example 4

[0043] The specific steps are shown in Example 2, except that 2-naphthaleneboric acid is used instead of 4-dimethylaminophenyl borate in Step 1. The final product is sodium 4-(naphthalene-2-yl)-7-oxocyclohepta-1,3,5-triene-1-olate, and the specific chemical formula is: The yield was 82%.

[0044] Example 5

[0045] The specific steps are shown in Example 2, except that 4-dimethylaminophenyl borate in step 1 is replaced by 4-biphenylboronic acid, and the final product is sodium 4-([1,1'-biphenyl]-4-yl)-7-oxocyclohepta-1,3,5-triene-1-olate, with a specific chemical formula structure of The yield was 85%.

[0046] Example 6

[0047] The specific steps are shown in Example 2, except that 4-dimethylaminophenyl borate in step 1 is replaced by 4-fluorophenylboric acid, and the final product is sodium 4-(4-fluorophenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, with the specific chemical formula being: The yield was 69%.

[0048] Example 7

[0049] The specific steps are shown in Example 2, except that 4-Methoxyphenylboronic acid was used to replace the 4-dimethylaminophenylboronic acid in step 1. The final product was sodium 4-(4-methoxyphenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, with a specific chemical formula of , and a yield of 76%.

[0050] Example 8

[0051] The specific steps are shown in Example 2, except that 4-dimethylaminophenyl borate in step 1 is replaced by 4-trifluoromethylphenylboronic acid, and the final product is sodium 4-(4-trifluoromethylphenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, with the specific chemical formula being: The yield was 72%.

[0052] Example 9

[0053] The specific steps are shown in Example 2, except that 4-dimethylaminophenyl borate in step 1 is replaced by 4-cyanophenylboronic acid, and the final product is sodium 4-(4-cyanophenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, with the specific chemical formula being: The yield was 60%.

[0054] Example 10

[0055] The specific steps are shown in Example 2, except that phenylboronic acid is used instead of 4-dimethylaminophenyl borate in Step 1. The final product is sodium 7-oxo-4-phenylcyclohepta-1,3,5-triene-1-olate, and the specific chemical formula is: The yield was 79%.

[0056] Example 11

[0057] The specific steps are shown in Example 1, except that potassium carbonate is used instead of sodium carbonate in step 1. The final product is potassium 7-oxocyclohepta-1,3,5-triene-1-olate, and the specific chemical formula is The yield was 99%.

[0058] Example 12

[0059] The specific steps are shown in Example 2, except that potassium carbonate is used instead of sodium carbonate in step 1. The final product is potassium 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, and the specific chemical formula is: The yield was 90%.

[0060] Example 13

[0061] The specific steps are shown in Example 2, except that potassium carbonate is used instead of sodium carbonate in step 1, and (4-morpholinophenyl)boric acid is used instead of 4-dimethylaminophenyl borate in step 1. The final product is potassium 4-(4-morpholinophenyl)-7-oxocyclohepta-1,3,5-triene-1-olate, and the specific chemical formula is: The yield was 78%.

[0062] Example 14

[0063] The product obtained in Example 8 was acidified with hydrochloric acid overnight to obtain 2-hydroxy-4-(4-trifluoromethylphenyl)-7-oxocyclohepta-1,3,5-triene-1-one, the specific chemical structure of which is: The yield was 100%.

[0064] Application Example 1

[0065] The compound 7-oxocyclohepta-1,3,5-triene-1-ol sodium prepared in Example 1 can be used as an organic photocatalyst to undergo a coupling reaction with an alkyl bromide compound under 450nm blue light irradiation to generate a Heck product. The chemical structure of the target compound finally obtained in this application example is The specific preparation process includes the following steps: 0.1 mmol of 1,1-diphenylethylene (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), 0.15 mmol of ethyl 2-bromopropionate (purchased from Shanghai Adamas Reagent Co., Ltd.), 0.2 mmol of sodium carbonate (purchased from Anhui Zesheng Technology Co., Ltd.), and 0.02 mmol of sodium 7-oxocyclohepta-1,3,5-triene-1-ol were weighed into a Schlenk flask, argon was replaced three times on the vacuum line, and 0.5 mL of acetonitrile (purchased from Shanghai Adamas Reagent Co., Ltd.) was added thereto under an inert atmosphere. After the addition was completed, the stopcock was screwed on and the product was placed in a photoreactor to react for 12 hours. After the reaction was completed, it was extracted with ethyl acetate and water, the organic phase was retained, dried, spin-dried, and separated by passing through a silica gel column with petroleum ether / ethyl acetate in a ratio of 100 to 1 to obtain the product, with a yield of 85%. Figures 7 and 8 The following are the H NMR and C NMR spectra of ethyl 2-methyl-4,4-diphenylbut-3-enoate prepared according to this application example. These spectra confirm the successful preparation of the target product, demonstrating that the tropolone compounds prepared in this invention can effectively act as reducing agents in the photoreaction. The specific reaction equation is shown below.

[0066]

[0067] When the potassium 7-oxocyclohepta-1,3,5-triene-1-olate in Example 11 was used to replace the sodium 7-oxocyclohepta-1,3,5-triene-1-olate in Application Example 1, the other steps were the same as in Application Example 1, and the yield of the final product was 50%.

[0068] When the sodium 4-(naphthalene-2-yl)-7-oxocyclohepta-1,3,5-triene-1-olate in Example 4 was used to replace the sodium 7-oxocyclohepta-1,3,5-triene-1-olate in Application Example 1, the other steps were the same as in Application Example 1, and the yield of the final product was 41%.

[0069] When the sodium 4-([1,1'-biphenyl]-4-yl)-7-oxocyclohepta-1,3,5-triene-1-olate in Example 5 was used to replace the sodium 7-oxocyclohepta-1,3,5-triene-1-olate in Application Example 1, the other steps were the same as in Application Example 1, and the yield of the final product was 35%.

[0070] When the sodium 4-(4-methoxyphenyl)-7-oxocyclohepta-1,3,5-triene-1-olate in Example 7 was used to replace the sodium 7-oxocyclohepta-1,3,5-triene-1-olate in Application Example 1, the other steps were the same as in Application Example 1, and the yield of the final product was 38%.

[0071] When 2-hydroxy-5-methylcyclohepta-2,4,6-triene-1-one was used to replace sodium 7-oxocyclohepta-1,3,5-triene-1-ol in Application Example 1, the other steps were the same as those in Application Example 1, and the yield of the final product was 0.

[0072] Through the above experiments, it can be found that when the 5-position substituent of the tropolone skeleton is H and aryl, the heck reaction in Application Example 1 can obtain considerable product yields, while when the 5-position substituent of the tropolone skeleton is alkyl, the yield is 0. It can be seen that the choice of the 5-position substituent of the tropolone skeleton disclosed in the present invention has an important influence on the efficiency of the photocatalyst.

[0073] Application Example 2

[0074] The compound 2-hydroxy-5-(4-morpholinophenyl)cyclohepta-2,4,6-triene-1-one prepared in Example 3 can be used as an organic photoreductant to undergo a coupling reaction with an alkyl NHPI ester under 450nm blue light irradiation to generate a Heck product. The chemical structure of the target compound finally obtained in this application example is The specific preparation process includes the following steps: 0.1 mmol of 1,1-stilbene (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), 0.03 mmol of potassium trifluoroacetate (purchased from Shanghai Adamas Reagent Co., Ltd.), 0.2 mmol of 1,3-dioxoindole-2-yl-2-(1-tosylpiperidin-4-yl) acetate, and 0.005 mmol of 2-hydroxy-5-(4-morpholinophenyl)cycloheptyl-2,4,6-triene-1-one are weighed into a Schlenk flask, argon is replaced three times on the vacuum line, and 1.0 mL of dimethyl sulfoxide (purchased from Shanghai Adamas Reagent Co., Ltd.) is added thereto under an inert atmosphere. After the addition is completed, the stopcock is screwed on and the flask is placed in a photoreactor to react for 12 hours. After the reaction is completed, the flask is extracted with ethyl acetate and water, the organic phase is retained, dried, spin-dried, and separated by passing through a silica gel column with petroleum ether / ethyl acetate in a ratio of 15 to 1 to obtain the product, with a yield of up to 98%. Figures 9 and 10The hydrogen and carbon nuclear magnetic resonance spectra of 4-(2,2-diphenylvinyl)-1-toluenesulfonylpiperidine prepared according to this application example are shown in Figures 1 and 2. The above spectra confirm the successful preparation of the target product, demonstrating that the tropolone compounds prepared in this invention can effectively act as reducing agents in the photoreaction. The specific reaction equation is shown below.

[0075]

[0076] When 2-hydroxy-4-(4-trifluoromethylphenyl)-7-oxocycloheptane-1,3,5-triene-1-one in Example 14 was used to replace 2-hydroxy-5-(4-morpholinophenyl)cycloheptane-2,4,6-triene-1-one in Application Example 2, the other steps were the same as in Application Example 2, and the yield of the final product was 52%.

[0077] When 2-hydroxy-5-methylcyclohepta-2,4,6-triene-1-one was used to replace 2-hydroxy-5-(4-morpholinophenyl)cyclohepta-2,4,6-triene-1-one in Application Example 1, the other steps were the same as those in Application Example 2, and the yield of the final product was 0.

[0078] Through the above experiments, it can be found that when the 5-position substituent of the tropolone skeleton is H and aryl, the heck reaction in Application Example 2 can obtain considerable product yields, while when the 5-position substituent of the tropolone skeleton is alkyl, the yield is 0. It can be seen that the choice of the 5-position substituent of the tropolone skeleton disclosed in the present invention has an important influence on the efficiency of the photocatalyst.

[0079] Application Example 3

[0080] The CF bond of trifluoromethyl aromatic hydrocarbons is relatively inert and difficult to reduce. The compound 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-ol sodium prepared in Example 2 can be used as an organic photoreducing agent to undergo a coupling reaction with trifluoromethyl aromatic hydrocarbon compounds under 450nm blue light irradiation to generate a hydroalkylation product. The chemical structure of the target compound finally obtained in this application example is The specific preparation process includes the following steps: 0.1 mmol of 1,1-diphenylethylene (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), 0.25 mmol of 1,3-bis(trifluoromethyl)benzene (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), 0.2 mmol of sodium tert-butoxide (purchased from Shanghai Adamas Reagent Co., Ltd.), 0.2 mmol of BIH (purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.), and 0.01 mmol of sodium 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-ol were weighed into a Schlenk flask, argon was replaced three times on the vacuum line, and 1 mL of acetonitrile / methanol (purchased from Shanghai Adamas Reagent Co., Ltd.) was added thereto in an inert atmosphere. After the addition was completed, the stopcock was screwed on and the product was placed in a photoreactor to react for 12 hours. After the reaction was completed, the product was extracted with ethyl acetate and water, the organic phase was retained, dried, spin-dried, and separated by passing through a silica gel column with petroleum ether / ethyl acetate in a ratio of 100 to 1 to obtain the product in a yield of 93%. Figures 11 to 13 The following are the hydrogen, carbon, and fluorine nuclear magnetic resonance spectra of (3,3-difluoro-3-(3-(trifluoromethyl)phenyl)propane-1,1-diyl)diphenyl prepared according to this application example. These spectra confirm the successful preparation of the target product and demonstrate that the tropolone compounds prepared in this invention can effectively act as reducing agents in photoreactions, activating the relatively inert C-F bonds. The specific reaction equation is shown below.

[0081]

[0082] When the potassium 4-(4-(dimethylamino)phenyl)-7-oxocycloheptane-1,3,5-triene-1-ol in Example 12 was used to replace the sodium 4-(4-(dimethylamino)phenyl)-7-oxocycloheptane-1,3,5-triene-1-ol in Application Example 3, the other steps were the same as in Application Example 3, and the yield of the final product was 70%.

[0083] When 2-hydroxy-5-methylcyclohepta-2,4,6-triene-1-one was used to replace sodium 4-(4-(dimethylamino)phenyl)-7-oxocyclohepta-1,3,5-triene-1-ol in Application Example 3, the other steps were the same as those in Application Example 3, and the yield of the final product was 0.

[0084] Through the above experiments, it can be found that when the 5-position substituent of the tropolone skeleton is H and aryl, the hydrogenation difluoroalkylation reaction in Application Example 2 can obtain considerable product yields, while when the 5-position substituent of the tropolone skeleton is alkyl, the yield is 0. It can be seen that the choice of the 5-position substituent of the tropolone skeleton disclosed in the present invention has an important influence on the efficiency of the photocatalyst.

[0085] It can be found through the specific application of the above application examples 1-3 that the toluhydroquinone compound prepared by the application has good photochemical activity, and the range of active electrophilic reagents is relatively wide. Therefore, the toluhydroquinone compound designed by the application has very good application value, greatly improving the application scene of such compounds.

[0086] The above only describes the preferred embodiments of the application, and it should be pointed out that those skilled in the art can make some improvements and refinements without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A photocatalyst based on a tropolone skeleton, characterized in that: The structural formula of the photocatalyst is Wherein, the M is selected from one of H, Na and K, and the R1 is one of H and aryl.

2. The photocatalyst according to claim 1, characterized in that The aryl group is selected from One of them.

3. A method for synthesizing the photocatalyst according to claim 1-2, characterized in that: The following steps are involved: Step 1: Under an inert gas atmosphere, 5-bromo-2-hydroxycyclohepta-2,4,6-trien-1-one, an aryl substituted boronic acid, a palladium catalyst, and a base are placed in a reaction vessel, a solvent is added to dissolve the reactants, and then the mixture is heated to a certain temperature and maintained for a certain period of time; Step 2: After the reaction is completed, the reactants are cooled to room temperature and separated to obtain the photocatalyst; Wherein, the R1 is selected from aryl.

4. The synthesis method according to claim 3, characterized in that The base is one or more of sodium carbonate, potassium carbonate, sodium tert-butoxide and potassium tert-butoxide.

5. A use of the photocatalyst according to any one of claims 1-2, characterized in that: The photocatalyst activates the carbon-halogen bond of the alkyl halide, so that the alkyl halide and the aryl olefin undergo a Heck coupling reaction.

6. Use of the photocatalyst according to any one of claims 1-2, characterized in that: The photocatalyst activates the alkyl NHPI ester to undergo decarboxylation, causing the alkyl NHPI ester to undergo a Heck coupling reaction with the aryl olefin.

7. Use of the photocatalyst according to any one of claims 1-2, characterized in that: The photocatalyst activates the carbon-fluorine bond of trifluoromethyl aromatic hydrocarbon, and trifluoromethyl aromatic hydrocarbon undergoes a hydrogenation difluoroalkylation reaction with aryl olefin.

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