Catalytic method for preparing methyl 2-furanacetate compound through photocatalysis

Abstract

The invention belongs to the technical field of catalytic methods and catalysts, and particularly relates to a catalytic method for preparing 2-methyl furanacetate compounds through photocatalysis, which is characterized in that CO2 participates in 1, 4-carbonylation / cycloisomerization reaction of 1, 3-enyne based on a photocatalytic system, and CO2 is used as a carboxyl source; no photosensitizer exists; compared with the prior art, the method has the advantages of high yield and good chemical selectivity, the reaction substrate range is wide, various functional groups such as methyl, methoxyl, phenyl and halogen can be compatible with the reaction, and the 1, 4-dihydropyridine compound substituted at different positions on the phenyl can also be compatible in a system and converted into a target product. The method has the advantages of simple operation, mild reaction conditions, starting from simple and easily available substrate raw materials, and avoiding of the use of complex substrates by adopting a three-component coupling mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic methods and catalysts, and particularly relates to a catalytic method for photocatalytic preparation of 2-furanacetic acid methyl ester compounds. Background Art

[0002] Polysubstituted furans and their derivatives are an important class of heterocyclic compounds. Their core structure is a furan ring (a five-membered heterocyclic ring containing one oxygen atom), and multiple substituents (such as alkyl, aryl, halogen, carbonyl, etc.) are connected to the ring. Such compounds have wide applications in the fields of organic synthesis, medicinal chemistry, materials science, etc. Furanacetic acid is one of the polysubstituted furans and has a good active structural unit. For example, in the study of compounds for treating neurokinin-mediated diseases disclosed in US Patent US 2005 / 0256164 A1, it was found that the carboxylic acid fragment of a specific furanacetic acid fragment exhibited good activity.

[0003] The existing synthesis methods of polysubstituted furans and their derivatives mainly include: (1) direct functionalization of the furan ring: introducing substituents onto the existing furan ring through electrophilic substitution or metal-catalyzed coupling reactions; (2) constructing polysubstituted furans from non-furan precursors: such as the Paal-Knorr synthesis method, which cyclizes 1,4-diketone compounds under acidic conditions to form furans; furfural (derived from biomass) is used to prepare polysubstituted furans through oxidation, reduction, or condensation reactions. For example, Invention Patent CN112898247B discloses a synthesis method of furanacetic acid esters. Using furfuryl alcohol compounds as raw materials, carbon monoxide gas as the carbonyl source, and ester compounds as additives, a carbonylation reaction is carried out in an organic solvent under the action of a catalyst to obtain furanacetic acid esters. The catalyst is a combination of a base, a palladium metal salt, and a phosphine ligand-containing ligand. However, the above methods have problems of low selectivity and conversion rate; using precious metal palladium as a catalyst is toxic to the environment and organisms, and there are also problems of high cost. The carbon monoxide gas used as the carbonyl source is toxic, etc., which limits their application. Moreover, the synthesis of furanacetic acid also faces problems such as a single product structure and the inability to construct furanacetic acid with multiple functional group substitutions, especially the green catalytic synthesis faces huge challenges. Therefore, how to develop new and efficient synthesis methods has always been a hot topic of concern for synthetic chemists.

[0004] Aiming at the above technical problems, the present invention provides a catalytic method for photocatalytic preparation of 2-furanacetic acid methyl ester compounds. Using photocatalysis, utilizing light energy, and reacting at room temperature without high temperature, greenhouse gas carbon dioxide is reduced and converted into high-value carboxylic acid derivatives, significantly improving the conversion rate and selectivity of 2-furanacetic acid, developing a green and environmentally friendly preparation method, reducing pollution, and improving the efficiency of the catalytic reaction and the preparation efficiency of 2-furanacetic acid methyl ester. Summary of the Invention

[0005] The object of the present invention is to provide a catalytic method for the photocatalytic preparation of methyl 2-furanoacetate compounds, comprising the following steps:

[0006] Wherein, R 1 is any one of tert-butyl, phenyl, and methyl; R 2 is any one of phenyl, 4-methoxyphenyl, 2-methoxyphenyl, 4-fluorophenyl, and ester group; R 3 is any one of phenyl, 4-methylphenyl, 4-chlorophenyl, piperonyl, naphthyl, and biphenyl; (1) Under an argon atmosphere, add a 1,3-enyne compound, a 1,4-dihydropyridine compound, and a base to a Schlenk reaction tube, add a solvent, and introduce carbon dioxide gas; (2) Place the reaction at room temperature and stir under visible light until the 1,3-enyne compound, 1,4-dihydropyridine compound, and base added in step (1) disappear; (3) After the reaction is completed, acidify the reaction solution, extract the aqueous phase, wash the combined organic phases, dry, and concentrate under reduced pressure; (4) Dissolve the organic phase obtained in step (3) in a mixed solution of dichloromethane and methanol, add a methylation reagent, react at room temperature, and after the reaction is completed, concentrate the organic phase under reduced pressure, filter, and obtain the target product.

[0007] Preferably, the base in step (1) is a carbonate, formate, alkoxide base, or hydroxide base.

[0008] Preferably, the carbonate in step (1) is cesium carbonate; the formate is one or more of cesium formate and potassium formate; the alkoxide salt is one or more of sodium methoxide, sodium tert-butoxide, lithium tert-butoxide, and sodium tert-pentoxide; the hydroxide base is potassium hydroxide.

[0009] Preferably, the solvent in step (1) is one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, tetrahydrofuran, dichloromethane, and toluene.

[0010] Preferably, the visible light in step (2) is blue light with a wavelength of 430-460 nm, and the light source power is 1-100 W.

[0011] Preferably, the methylation reagent in step (4) is trimethylsilyldiazomethane.

[0012] Preferably, the ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol in step (4) is 4:1.

[0013] Preferably, the reaction temperature in step (2) is 25-30 °C and the reaction time is 24 hours.

[0014] The beneficial effects of the present invention are as follows: The present invention provides a catalytic method for the photocatalytic preparation of methyl 2-furanoacetates, based on the CO 2 participation in the 1,4-carbonylation / ring isomerization reaction of 1,3-enynes, using CO 2 as the carboxyl source; without a photosensitizer; having a high yield and good chemoselectivity. The reaction substrates of the present invention have a wide range, and various functional groups such as methyl, methoxy, phenyl, and halogen can be compatible with this reaction. 1,4-dihydropyridine compounds with different substitutions at different positions on the phenyl can also be compatible in the system and converted into the target product. The reaction conditions are mild, and starting from simple and readily available substrate raw materials, a three-component coupling method is adopted to avoid the use of complex substrates. Detailed implementation manners

[0015] The protection scope of the present invention will be further described below through specific examples, but it should not be understood that the scope of the above-mentioned subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention.

[0016] It should be noted that in the following examples, unless otherwise specified, the methods are all conventional methods, and the reagents can all be obtained through commercial channels.

[0017] In the following examples, the trimethylsilyldiazomethane (TMSCHN 2 , Trimethylsilyl)diazomethane) is a safe and stable diazomethane (CH 2 N 2 ) alternative reagent, widely used in methylation, cyclopropanation, dipolar cycloaddition and other reactions. Compared with highly toxic and explosive diazomethane, TMSCHN 2 has the advantages of simple operation, stable storage, and lower toxicity.

[0018] In the following examples, the Ir[(ppy) 2 (dtbbpy)]PF 6 is an important cationic iridium(III) complex, widely used in organic optoelectronic materials (such as OLED, photocatalysis, bioimaging) and photochemical research (such as photosensitization, photoredox catalysis).

[0019] In the following examples, the Ir[(dF(CF 3 )ppy) 2 (dtbbpy)]PF 6It is an iridium(III) complex modified by fluorine atoms and trifluoromethyl groups, belonging to cationic phosphorescent materials. It has more advantages than traditional Ir(ppy) 3 derivatives in terms of photophysical properties, stability and application scope, and is particularly outstanding in the fields of deep red light / near-infrared luminescence, photocatalysis and bioimaging.

[0020] In the following examples, the fac -Ir(ppy) 3 (tris(2-phenylpyridine)iridium) is the most classic green phosphorescent material in iridium(III) complexes and can be used as a photocatalyst.

[0021] In the following examples, the 4CzIPN is a typical thermally activated delayed fluorescence (TADF) material, which realizes efficient reverse intersystem crossing (RISC) through the strong donor-acceptor (D-A) structure of carbazole (Cz) and cyano (CN).

[0022] In the following examples, the Schlenk reaction tube is a laboratory glass instrument designed specifically for anhydrous and anaerobic operations, and is widely used in air / moisture-sensitive chemical reactions (such as organometallic synthesis, transition metal catalysis, free radical reactions, etc.).

[0023] Example 1 Under an argon atmosphere, 1-(4,4-dimethyl-3-methylidenepent-1-ynyl)-4-methoxybenzene 1a (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube, 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. After combining the organic phases, the organic phases were washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3aa.

[0024]

[0025] The product detection data is as follows: Yellow oil, yield 75%.

[0026] 1 H NMR (400 MHz, CDCl 3 ) δ 7.62 (d, J J = 8.0 Hz, 2H), 7.37 – 7.34 (m, 4H), 7.24 – 7.21 (m, 1H), 6.89 (d, J J = 8.1 Hz, 2H), 6.59 (s, 1H), 5.31 (s, 1H), 3.80 (s, 3H), 3.75 (s, 3H), 1.33 (s, 9H).

[0027] 13 C NMR (100 MHz, CDCl 3 ) δ 171.4, 158.8, 151.4, 144.2, 132.6, 130.7, 123.0, 129.0, 128.5, 127.0, 123.5, 113.8, 106.1, 55.2, 52.6, 49.9, 31.4, 30.3.

[0028] Example 2 Under an argon atmosphere, 1-(4,4-dimethyl-3-methylidenepent-1-ynyl)-4-fluorobenzene 1b (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ba.

[0029]

[0030] The product detection data are as follows: Yellow solid, yield 52%.

[0031] 1 H NMR (400 MHz, CDCl 3 ): δ 7.65 (d, J J = 7.6 Hz, 2H), 7.45 – 7.38 (m,4H), 7.29 (d, J J = 8.0 Hz, 1H), 7.10 – 7.06 (m, 2H), 6.60 (s, 1H), 5.38 (s,1H), 3.80 (s, 3H), 1.37 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.0, 162.1 (d, J J = 245.0 Hz), 151.6,143.6, 132.9, 132.6 (d, J J = 4.0 Hz), 130.6, 130.5 (d, J J = 8.0 Hz), 128.6,127.2, 123.5, 115.4 (d, J J = 22.0 Hz), 106.2, 52.70, 49.8, 31.3, 30.3. 19 F NMR (377 MHz, CDCl 3 ): δ -115.2.

[0032] Example 3 Under an argon atmosphere, 1-(4,4-dimethyl-3-methylidenepent-1-ynyl)-2-methoxybenzene 1c (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted 5 times with ethyl acetate. After combining the organic phases, the organic phases were washed 3 times with saturated brine, and anhydrous Na2 SO 4 Dry the organic phase, and then concentrate the organic phase under reduced pressure. After that, dissolve the organic phase in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and add trimethylsilyldiazomethane (0.4 mmol). Place the reaction at room temperature for 1 hour. After the reaction is completed, concentrate the organic phase under reduced pressure and filter it through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ca.

[0033]

[0034] The product detection data are as follows: Yellow solid, yield 70%.

[0035] 1 H NMR (400 MHz, CDCl 3 ): δ 7.60 (d, J J = 8.0 Hz, 2H), 7.35 – 7.31 (m,2H), 7.28 – 7.18 (m, 3H), 6.94 – 6.87 (m, 2H), 6.62 (s, 1H), 5.74 (s, 1H),3.85 (s, 3H), 3.74 (s, 3H), 1,29 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.4, 156.4, 151.4, 143.8, 133.0, 130. 8,129.8, 128. 6, 128.5, 127.0, 126.0, 123.4, 120.6, 110.2, 106.2, 55.4, 52.5,44.2, 31.1, 30.3.

[0036] Example 4 Under an argon atmosphere, 1-(4,4-dimethyl-3-methylidenepent-1-ynyl)-4-(4-ethylphenyl)benzene 1d (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried and then concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3da.

[0037]

[0038] The detection data of the product are as follows: White solid, yield 70%.

[0039] 1 H NMR (400 MHz, CDCl 3 ): δ 7.62 (d, J = 7.6 Hz, 2H), 7.56 (d, J = 8.4Hz, 2H), 7.51 – 7.46 (m, 4H), 7.36 – 7.33 (m, 2H), 7.26 – 7.20 (m, 3H), 6.60(s, 1H), 5.40 (s, 1H), 3.76 (s, 3H), 2.68 (q, J = 7.6, 15.2 Hz, 2H), 1.34 (s,9H), 1.26 (t, J = 7.6 Hz, 3H). 13 C NMR (100 MHz, CDCl 3): δ 171.2, 151.5, 143.8, 143.4, 140.2, 138.1, 135.5, 132.9, 130.7, 129.3, 128.6, 128.2, 127.1, 127.0, 123.5, 106.2, 52.7, 50.4, 31.4, 30.4, 28.5, 15.6.

[0040] Example 5 Under an argon atmosphere, 4-methoxy-1-(non-1-en-3-yn-2-yl)benzene 1e (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. After combining the organic phases, the organic phase was washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ea.

[0041]

[0042] The product detection data is as follows: Yellow oil, yield 50%.

[0043] 1 H NMR (400 MHz, CDCl 3 ): δ 7.69 (d, J = 7.2 Hz, 2H), 7.42 – 7.37 (m, 4H), 7.28 – 7.24 (m, 1H), 6.97 (d, J= 8.8 Hz, 2H), 6.73 (s, 1H), 3.85 (s,3H), 3.73 (s, 3H), 2.13 – 1.97 (m, 2H), 1.26 – 1.19 (m, 6H), 0.81 – 0.78 (m,3H). 13 C NMR (100 MHz, CDCl 3 ): δ 172.5, 158.7, 152.4, 146.1, 130.6, 129.2,128.6, 127.3, 125.8, 125.4, 123.6, 114.1, 106.8, 55.3, 52.3, 43.6, 31.3,30.5, 26.9, 22.3, 13.9.

[0044] Example VI Under an argon atmosphere, 3-butyn-1-ylbenzene 1f (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3fa.

[0045]

[0046] The detection data of the product are as follows: Yellow oil, yield 51%.

[0047] 1 H NMR (400 MHz, CDCl 3 ): δ 7.53 (d, J= 8.4 Hz, 2H), 7.34 (d, J = 8.0Hz, 2H), 7.29 – 7.22 (m, 5H), 7.16 – 7.12 (m, 1H), 6.50 (d, J = 3.6 Hz, 1H),6.19 (d, J = 3.2 Hz, 1H), 5.01 (s, 1H), 3.66 (s, 3H). 13 C NMR (100 MHz, CDCl 3 ): δ 170.9, 153.6, 151.1, 136.0, 130.6, 128.7,128.6, 128.5, 127.8, 127.2, 123.6, 110.2, 105.7, 52.6, 51.4.

[0048] Example 7 Under an argon atmosphere, 1 g (0.3 mmol) of (3-methylbut-3-en-1-ynyl)benzene, 0.2 mmol of ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a, and 0.6 mmol of cesium carbonate were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ga.

[0049]

[0050] The product detection data is as follows: Yellow oil, yield 59%.

[0051] 1 H NMR (400 MHz, CDCl 3): δ 7.52 (d, J J = 8.4 Hz, 2H), 7.33 (d, J J = 8.4Hz, 2H), 7.28 – 7.24 (m, 4H), 7.22 – 7.18 (m, 1H), 7.15 – 7.12 (m, 1H), 6.40(s, 1H), 5.02 (s, 1H), 3.67 (s, 3H), 1.91 (s, 3H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.0, 152.3, 145.4, 136.3, 130.7, 128.7,128.5, 127.5, 127.1, 123.6, 118.9, 108.7, 52.6, 49.4, 10.0.

[0052] Example VIII Under an argon atmosphere, 1-(but-3-en-1-ynyl)-4-methylbenzene 1h (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane: methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE: EA = 60:1 - 20:1) to obtain the target product 3ha.

[0053]

[0054] The detection data of the product are as follows: Yellow oil, yield 53%.

[0055] 1 H NMR (400 MHz, CDCl3 ): δ 7.61 (d, J = 8.8 Hz, 2H), 7.36 – 7.30 (m,4H), 7.24 – 7.20 (m, 1H), 7.17 (d, J = 7.6 Hz, 2H), 6.58 (d, J = 3.2 Hz, 1H),6.26 (d, J = 3.2 Hz, 1H), 5.06 (s, 1H), 3.75 (s, 3H), 2.34 (s, 3H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.1, 153.6, 151.3, 137.6, 133.0, 130.7,129.4, 128.6, 128.4, 127.2, 123.6, 110.1, 105.7, 52.6, 51.0, 21.1.

[0056] Example 9 Under argon atmosphere, (4-phenylbut-1-en-3-yn-2-yl)benzene 1i (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ia.

[0057]

[0058] The detection data of the product are as follows: Yellow oil, yield 65%.

[0059] 1 1H NMR (400 MHz, CDCl 3 ): δ 7.69 (d, J J = 8.4 Hz, 2H), 7.64 – 7.60 (m, 4H), 7.48 – 7.43 (m, 4H), 7.39 – 7.35 (m, 3H), 7.32 – 7.28 (m, 1H), 6.64 (s, 1H), 5.39 (s, 1H), 3.77 (s, 3H), 1.35 (s, 9H). 13 13C NMR (100 MHz, CDCl 3 ): δ 171.2, 151.3, 144.0, 140.6, 139.6, 136.8, 133.0, 129.7, 128.9, 128.8, 128.5, 127.4, 127.3, 127.2, 126.8, 123.9, 106.4, 52.6, 50.7, 31.4, 30.4.

[0060] Example X Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-4-[(2-methoxyphenyl)carbonyl]-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2b (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 2 4 2SO4. The organic phase was then concentrated under reduced pressure. Subsequently, the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3jb.

[0061]

[0062] The product detection data is as follows: Yellow oil, yield 71%.

[0063] 1 H NMR (400 MHz, CDCl 3 ): δ 7.78 – 7.76 (m, 2H), 7.40 (d, J J = 8.4 Hz, 2H), 7.34 – 7.31 (m, 2H), 7.28 – 7.17 (m, 2H), 7.00 – 6.96 (m, 1H), 6.92 (d, J J = 8.4 Hz, 1H), 6.86 (s, 1H), 5.37 (s, 1H), 3.92 (s, 3H), 3.73 (s, 3H), 1.33(s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.4, 155.2, 148.0, 143.0, 137.1, 132.8, 129.0, 128.5, 127.8, 127.4, 126.0, 120.8, 119.7, 111.1, 110.8, 55.4, 52.7, 50.7, 31.5, 30.4. Example XI Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-4-[(3-methoxyphenyl)carbonyl]-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2c (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and anhydrous Na 2 SO 4Dry the organic phase, and then concentrate the organic phase under reduced pressure. After that, dissolve the organic phase in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane: methanol = 4:1), and add trimethylsilyldiazomethane (0.4 mmol). Place the reaction at room temperature for 1 hour. After the reaction is completed, concentrate the organic phase under reduced pressure and filter it through a silica gel column (PE: EA = 60:1 - 20:1) to obtain the target product 3jc.

[0064]

[0065] The product detection data is as follows: Yellow solid, yield 67%.

[0066] 1 H NMR (400 MHz, CDCl 3 ): δ 7.41 (d, J = 8.4 Hz, 2H), 7.36 – 7.32 (m,2H), 7.30 – 7.20 (m, 3H), 7.13 (s, 1H), 6.78 (d, J = 8.0 Hz, 1H), 6.58 (s,1H), 5.35 (s, 1H), 3.83 (s, 3H), 3.74 (s, 3H), 1.32 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.1, 159.7, 151.3, 143.9, 136.8, 132.9,132.0, 129.6, 128.9, 128.5, 127.4, 116.2, 112.7, 109.0, 106.5, 55.2, 52.6,50.7, 31.4, 30.3. Example Twelve Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 4-(benzo[d][1,3]dioxole-5-carbonyl)-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2d (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. After combining the organic phases, the organic phase was washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried and then concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3jd.

[0067]

[0068] The product detection data are as follows: Yellow oil, yield 60%.

[0069] 1 H NMR (400 MHz, CDCl 3 ): δ 7.40 (d, J = 8.4 Hz, 2H), 7.36 – 7.32 (m,2H), 7.29 – 7.25 (m, 1H), 7.12 – 7.08 (m, 2H), 6.79 (d, J = 8.0 Hz, 1H), 6.44(s, 1H), 5.95 (s, 2H), 5.34 (s, 1H), 3.74 (s, 3H), 1.31 (s, 9H). 13 C NMR (100 MHz, CDCl 3): δ 171.2, 151.3, 147.8, 146.8, 143.2, 136.9, 132.8, 128.8, 128.5, 127.4, 125.3, 117.4, 108.5, 105.0, 104.4, 101.0, 52.6, 50.6, 31.4, 30.3. Example XIII Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-2,6-dimethyl-4-[(4-methylphenyl)carbonyl]-1,4-dihydropyridine-3-carboxylate 2e (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. After combining the organic phases, the organic phase was washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried and then concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3je.

[0070]

[0071] The product detection data are as follows: Yellow solid, yield 79%.

[0072] 1 H NMR (400 MHz, CDCl 3 ): δ 7.55 (d, J = 8.0 Hz, 2H), 7.45 (d, J = 7.2Hz, 2H), 7.40 – 7.36 (m, 2H), 7.33 – 7.29 (m, 1H), 7.19 (d, J= 7.6 Hz, 2H), 6.57 (s, 1H), 5.40 (ss, 1H), 3.78 (s, 3H), 2.38 (s, 3H), 1.36 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.2, 151.7, 143.4, 136.9, 136.8, 132.7, 129.2, 128.8, 128.4, 128.0, 127.3, 123.4, 105.3, 52.5, 50.6, 31.3, 30.3, 21.2. Example XIV Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-2,6-dimethyl-4-[(4-phenylphenyl)carbonyl]-1,4-dihydropyridine-3-carboxylate 2f (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 SO 4 The organic phase was dried and then concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3jf.

[0073]

[0074] The detection data of the product are as follows: White solid, yield 57%.

[0075] 1 H NMR (400 MHz, CDCl 3 ): δ 7.70 (d, J= 8.4 Hz, 2H), 7.64 – 7.60 (m,4H), 7.48 – 7.44 (m, 4H), 7.39 – 7.36 (m, 3H), 7.34 – 7.29 (m, 1H), 6.65 (s,1H), 5.40 (s, 1H), 3.78 (s, 3H), 1.36 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ): δ 171.2, 151.3, 144.0, 140.6, 139.6, 136.8,133.0, 129.7, 128.9, 128.8, 128.5, 127.4, 127.3, 127.2, 126.8, 123.9, 106.4,52.6, 50.7, 31.4, 30.4. Example XV Under an argon atmosphere, (4,4-dimethyl-3-methylenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ja.

[0076]

[0077] The detection data of the product are as follows: White solid, yield 79%.

[0078] 1 H NMR (400 MHz, CDCl 3) δ 7.61 (d, J J = 8.4 Hz, 2H), 7.42 (d, J J = 8.4Hz, 2H), 7.37 – 7.33 (m, 4H), 7.30 (d, J J = 8.4 Hz, 1H), 7.24 – 7.20 (m, 1H),6.59 (s, 1H), 5.36 (s, 1H), 3.75 (s, 3H), 1.33 (s, 9H). 13 13C NMR (100 MHz, CDCl 3 ) δ 171.2, 151.6, 143.9, 136.9, 132.9, 130.8,129.0, 128.6, 128.5, 127.4, 127.1, 123.6, 106.2, 52.7, 50.8, 31.4, 30.4. Example XVI Under an argon atmosphere, 4-chloro-1-(nona-1-en-3-yn-2-yl)benzene 1k (0.3 mmol), ethyl 4-phenylcarbonyl-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2a (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 2 4 2SO4. The organic phase was then concentrated under reduced pressure. Subsequently, the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ka.

[0079]

[0080] The product detection data is as follows: Yellow oil, yield 67%.

[0081] 11H NMR (400 MHz, CDCl 3 ) δ 7.68 (d, J J = 8.4 Hz, 2H), 7.43 – 7.37 (m,6H), 7.29 – 7.25 (m, 1H), 6.72 (s, 1H), 3.85 (dd, J J = 8.8, 6.8 Hz, 1H), 3.73(s, 3H), 2.15 – 1.99 (m, 2H), 1.28 – 1.19 (m, 6H), 0.81 – 0.78 (m, 3H). 13 13C NMR (100 MHz, CDCl 3 ) δ 172.2, 152.8, 146.7, 133.0, 131.8, 130.3,129.4, 128.9, 128.6, 127.5, 124.8, 123.7, 106.4, 52.3, 43.7, 31.3, 30.4,26.8, 22.3, 13.9. Example XVII Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 4-[(4-chlorophenyl)carbonyl]-5-(ethoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2g (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was displaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 2 4 SO

[0082]

[0083] The detection data of the product are as follows: White solid, yield 61%.

[0084] 1 H NMR (400 MHz, CDCl 3 ) δ 7.52 (d, J J = 8.4 Hz, 2H), 7.41 – 7.29 (m,7H), 6.58 (s, 1H), 5.36 (s, 1H), 3.76 (s, 3H), 1.33 (s, 9H). 13 C NMR (100 MHz, CDCl 3 ) δ 171.1, 150.5, 144.2, 136.7, 133.1, 132.6,129.2, 128.84, 128.75, 128.5, 127.5, 124.8, 106.6, 52.6, 50.7, 31.3, 30.4. Example XVIII Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-4-[(4-methoxyphenyl)carbonyl]-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2h (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried with anhydrous Na 2 SO 4 The organic phase was dried, and then the organic phase was concentrated under reduced pressure. Then the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3jh.

[0085]

[0086] The product detection data is as follows: White solid, yield 82%.

[0087] 11H NMR (400 MHz, CDCl 3 ) δ 7.44 (d, J J = 8.4 Hz, 2H), 7.31(d, J J = 7.2Hz, 2H), 7.25 – 7.21 (m, 2H), 7.17 – 7.14 (m, 1H), 6.77 (d, J J = 8.8 Hz, 2H),6.35 (s, 1H), 5.25 (s, 1H), 3.67 (s, 3H), 3.62 (s, 3H), 1.22 (s, 9H). 13 13C NMR (100 MHz, CDCl 3 ) δ 171.2, 158.8, 151.5, 143.0, 137.0, 132.7,128.8, 128.4, 127.3, 124.9, 123.8, 113.9, 104.5, 55.1, 52.4, 50.6, 31.3,30.3. Example XIX Under an argon atmosphere, (4,4-dimethyl-3-methylidenepent-1-ynyl)benzene 1j (0.3 mmol), ethyl 5-(ethoxycarbonyl)-4-(furan-2-carbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylate 2i (0.2 mmol), and cesium carbonate (0.6 mmol) were added to a dry 10 mL Schlenk reaction tube. 3 mL of dimethyl sulfoxide was added, and then the carbon dioxide gas was replaced three times. The reaction was stirred at room temperature under a 12 W 460 nm LED blue light for 24 h until the raw materials disappeared. After the reaction was completed, the reaction solution was acidified with dilute hydrochloric acid, and the aqueous phase was extracted with ethyl acetate 5 times. The combined organic phases were washed with saturated brine 3 times, and dried over anhydrous Na 2 2 4 2SO4. The organic phase was then concentrated under reduced pressure. Subsequently, the organic phase was dissolved in a 5 mL mixed solution of dichloromethane and methanol (dichloromethane:methanol = 4:1), and trimethylsilyldiazomethane (0.4 mmol) was added. The reaction was carried out at room temperature for 1 hour. After the reaction was completed, the organic phase was concentrated under reduced pressure and filtered through a silica gel column (PE:EA = 60:1 - 20:1) to obtain the target product 3ji.

[0088]

[0089] The product detection data are as follows: Yellow oily substance, yield 60%.

[0090] 1 H NMR (400 MHz, CDCl 3 ) δ 7.39 – 7.31 (m, 5H), 7.29 – 7.24 (m, 1H), 6.50 – 6.48 (m, 2H), 6.42 – 6.41 (m, 1H), 5.35 (s, 1H), 3.73 (s, 3H), 1.31(s, 9H). 13 C NMR (100 MHz, CDCl 3 ) δ 171.0, 146.6, 144.5, 143.6, 141.5, 136.7, 132.6, 128.8, 128.5, 127.4, 111.3, 106.2, 104.9, 52.6, 50.5, 31.3, 30.3. Example 20 According to the method described in Example 15, the photocatalyst, base or solvent was changed simultaneously or separately, and the effect on the yield was observed.

[0091]

[0092] The changes in conditions and product yields are compared as shown in Table 1.

[0093] Table 1 Screening of reaction conditions Serial number Photocatalyst Base Solvent Yield (%) 1 PC1 <![CDATA[Cs 2 CO 3 > DMSO 59 2 PC1 HCOOCs DMSO 16 3 PC1 MeONa DMSO 27 4 PC1 <![CDATA[LiO t Bu]]> DMSO 50 5 PC1 <![CDATA[NaO t Bu]]> DMSO 55 6 PC1 <![CDATA[Cs 2 CO 3 > DMA 45 7 PC1 <![CDATA[Cs 2 CO 3 > NMP 49 8 PC1 <![CDATA[Cs 2 CO 3 > <![CDATA[CH 3 CN]]> N.R. 9 PC2 <![CDATA[Cs 2 CO 3 > DMSO 69 10 PC3 <![CDATA[Cs 2 CO 3 > DMSO 33 11 PC4 <![CDATA[Cs 2 CO 3 > DMSO 67 12 - <![CDATA[Cs 2 CO 3 > DMSO 79 13 - - DMSO N.R. <![CDATA[14 a > - <![CDATA[Cs 2 CO 3 > DMSO N.R. Note: PC1 = Ir[(ppy) 2 dtbbpy]PF 6 ,PC2 = Ir[(dF(CF 3 )ppy) 2 dtbbpy]PF 6 ,PC3 = fac -Ir(ppy) 3 ,PC4 = 4CzIPN. The yields in Table 1 are NMR yields with mesitylene trimethoxybenzene as the internal standard. a No light irradiation, other groups irradiated with blue light.

[0094] As can be seen from the data results in Table 1, the separation yield is as high as 79% under the reaction conditions of the present invention. A series of control experiments show that light and base play an indispensable role in the reaction, and the target product cannot be obtained without either of them. In the absence of a photosensitizer, the reaction yield reaches the highest. When different bases are replaced, the yield decreases, and strong bases have better effects than weak bases. When the solvent DMA is replaced, the yield decreases, mainly manifested as the remaining raw materials. In summary, it can be seen that both 1,3-enyne compounds and 1,4-dihydropyridine compounds are synthesized into methyl 2-furoate compounds with high yields and good chemoselectivity. Multiple functional groups such as methyl, methoxy, phenyl, and halogen can be compatible with this reaction. 1,4-Dihydropyridine compounds substituted at different positions on the phenyl can also be compatible in the system and converted into the target product.

[0095] In summary, the present invention provides a catalytic method for the photocatalytic preparation of methyl 2-furoate compounds, which is based on the CO of the photocatalytic system 2 participating in the 1,4-carbonylation / ring isomerization reaction of 1,3-enyne, with CO 2 as the carboxyl source; without a photosensitizer; having a high yield and good chemoselectivity, the reaction substrate range of the present invention is wide, and multiple functional groups such as methyl, methoxy, phenyl, and halogen can be compatible with this reaction. 1,4-Dihydropyridine compounds substituted at different positions on the phenyl can also be compatible in the system and converted into the target product. The reaction conditions are mild, and starting from simple and easily available substrate raw materials, a three-component coupling method is adopted to avoid the use of complex substrates.

Claims

1. A catalytic method for preparing methyl 2-furanacetate compounds by photocatalysis, characterized in that: The steps include: ； Among them, R 1 is any one of tert-butyl, phenyl and methyl; R 2 is any one of phenyl, 4-methoxyphenyl, 2-methoxyphenyl, 4-fluorophenyl, and ester; R 3 Any one of phenyl, 4-methylphenyl, 4-chlorophenyl, piperonyl, naphthyl and biphenyl; (1) Under argon environment, add 1,3-eneyne compounds, 1,4-dihydropyridine compounds and base into a Schlenk reaction tube, add solvent, and introduce carbon dioxide gas; (2) stirring the reaction mixture at room temperature under visible light until the 1,3-eneyne compound, 1,4-dihydropyridine compound and base added in step (1) disappear; (3) After the reaction is completed, the reaction solution is acidified, the aqueous phase is extracted, and the organic phases are combined, washed, dried, and concentrated under reduced pressure; (4) The organic phase obtained in step (3) is dissolved in a mixed solution of dichloromethane and methanol, and a methylating agent is added to react at room temperature. After the reaction is completed, the organic phase is concentrated under reduced pressure and filtered to obtain the target product.

2. The catalytic method according to claim 1, characterized in that The base in step (1) is a carbonate, a formates, an alkoxy base or a hydroxide base.

3. The catalytic method according to claim 2, characterized in that: The carbonate described in step (1) is cesium carbonate; the formate described is one or more of cesium formate and potassium formate; the alkoxy salt described is one or more of sodium methoxide, sodium tert-butoxide, lithium tert-butoxide or sodium tert-amylate; and the hydroxide base described is potassium hydroxide.

4. The catalytic method according to claim 1, characterized in that The solvent in step (1) is one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, tetrahydrofuran, dichloromethane or toluene.

5. The catalytic method according to claim 1, characterized in that: The visible light described in step (2) is 430-460 nm blue light, and the light source power is 1-100 W.

6. The catalytic method according to claim 1, characterized in that: The methylating agent in step (4) is trimethylsilyldiazomethane.

7. The catalytic method according to claim 1, characterized in that: The ratio of dichloromethane to methanol in the mixed solution of dichloromethane and methanol in step (4) is 4:

1.

8. The catalytic method according to claim 1, characterized in that: The reaction temperature in step (2) is 25-30°C and the reaction time is 24 hours.

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