A method for selectively synthesizing trans-olefins by semi-reduction of diaryl alkynes catalyzed by elemental sulfur

Abstract

The present invention discloses a method for the semi-reductive selective synthesis of trans-olefins from diaryl alkynes catalyzed by elemental sulfur, belonging to the technical field of catalytic synthesis of fine chemical products. The method comprises mixing diaryl alkynes, elemental sulfur, water, and an organic solvent under the protection of an inert gas, and then conducting a semi-reductive selective synthesis reaction to obtain trans-olefins. The method uses elemental sulfur as a catalyst precursor and water and an organic solvent as a hydrogen source and solvent, achieving efficient semi-reductive selective synthesis of trans-olefins from alkynes.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic synthesis of fine chemical products, and in particular to a method for selectively synthesizing trans-olefins from diaryl alkynes by semi-reduction catalyzed by elemental sulfur. Background Art

[0002] Olefins with well-defined E / Z configurations are key synthetic intermediates, widely distributed in pharmaceutical molecules, functional materials, and natural products, playing a vital role. In recent years, researchers have devoted significant effort to developing efficient methods for E-stereoselective olefin reactions. Transition-metal-catalyzed alkyne semireduction is one of the most classic approaches, with metals such as rhodium (Rh), ruthenium (Ru), palladium (Pd), iridium (Ir), copper (Cu), and even iron (Fe) successfully employed in alkyne semireduction reactions. However, most of these transition-metal-catalyzed methods suffer from inherent drawbacks such as high catalyst costs, residual metal contamination, ligand dependence, and limited functional group tolerance. Therefore, developing metal-free catalytic systems for alkyne semireduction is both of great significance and a challenging task.

[0003] Metal-free catalysis has become the most important and attractive research direction in the field of organic chemistry due to its environmental friendliness. Recently, researchers have developed sulfur-based Na2S·9H2O / DMF (Chen Z, Luo M, Wen Y, et al. Transition-metal-free semihydrogenation of diarylalkynes: highly stereoselective synthesis of trans-alkenes using Na2S·9H2O[J]. Organicletters, 2014, 16(11): 3020-3023.), CS2 / KOH / DMF / H2O (Paixão DB, Soares E GO, Silva CDG, et al. CS2 / KOH System-Promoted Stereoselective Synthesis of (E)-Alkenes from Diarylalkynes and a “Hidden” Zinin-Type Reductionof Nitroarenesinto Arylamines[J]. The Journal of Organic Chemistry). Chemistry,2023,88(24):17037-17046.), EtOCS2K / DMF / H2O(Luo X,Chen X,Chen L,et al. Communications, 2019, 55(15):2170-2173), KCS2OEt / HCO2H / DMF (Prasanna R, Guha S, Sekar G. Proton-coupled electron transfer: transition-metal-free selective reduction of chalcones andalkynes using xanthate / formic acid[J].Organic Letters, 2019, 21(8): 2650-2653.) and other systems are used for the semi-reduction reaction of alkynes to prepare E-stereoselective alkenes, but these systems either rely on pre-synthesized sulfides or use highly toxic sulfides, which seriously limits their industrial application.

[0004] Elemental sulfur is a natural, non-toxic and inexpensive reagent. To date, there has been no report on the application of elemental sulfur in catalyzing the semi-hydrogenation of alkynes in the technical field of the invention. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method for the semi-reductive selective synthesis of trans-olefins from diaryl alkynes catalyzed by elemental sulfur. Elemental sulfur (S8) is used as a catalyst precursor, and water and an organic solvent are used as a hydrogen source and solvent to achieve efficient semi-reductive selective synthesis of trans-olefins from alkynes.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for the semi-reductive selective synthesis of trans-olefins from diaryl alkynes catalyzed by elemental sulfur comprises mixing diaryl alkynes, elemental sulfur, water and an organic solution under the protection of an inert gas, and then performing a semi-reductive selective synthesis reaction to obtain trans-olefins.

[0008] The diaryl alkyne is one of diphenyl acetylene, 2-(phenylethynyl)naphthalene, 1-methyl-3-(phenylethynyl)benzene, 1-methyl-4-(phenylethynyl)benzene, 1-methyl-2-(phenylethynyl)benzene, ‌4-(phenylethynyl)-1,1'-biphenyl, 1-ethyl-4-(phenylethynyl)benzene, 1-tert-butyl-4-(phenylethynyl)benzene, 1-methoxy-4-(phenylethynyl)benzene, ‌1-fluoro-4-(phenylethynyl)benzene, 1-chloro-4-(phenylethynyl)benzene, ‌1-bromo-4-(phenylethynyl)benzene, and ‌1-trifluoromethyl-4-(phenylethynyl)benzene;

[0009] Preferably, the elemental sulfur is sulfur powder;

[0010] The organic solvent is one of N,N-dimethylformamide, N-methylformamide, N,N-dimethylaniline, triethylamine, ethanolamine, n-butylamine, dimethyl sulfoxide, pyridine, and N-methylpyrrolidone;

[0011] Preferably, the organic solution is N,N-dimethylformamide;

[0012] The molar ratio of diaryl alkyne to elemental sulfur is 1:2-4;

[0013] Preferably, the molar ratio of diaryl alkyne to elemental sulfur is 1:4;

[0014] The ratio of diaryl alkyne to water is 0.25 mmol: 25-30 μL;

[0015] Preferably, the ratio of diaryl alkyne to water is 0.25 mmol:27 μL;

[0016] The ratio of diaryl alkyne to organic solvent is 0.25mmol:0.8-1.2mL;

[0017] Preferably, the ratio of diaryl alkyne to organic solvent is 0.25 mmol:1 mL;

[0018] Preferably, the inert gas is nitrogen;

[0019] Preferably, the semi-reductive selective synthesis reaction is carried out in a closed environment;

[0020] The semi-reductive selective synthesis reaction temperature is 100-150°C and the time is 6-13h;

[0021] Preferably, the temperature of the semi-reductive selective synthesis reaction is 140° C. and the time is 12 h;

[0022] Preferably, the semi-reductive selective synthesis reaction is carried out under stirring conditions;

[0023] Furthermore, after the semi-reductive selective synthesis reaction is completed, post-treatment is performed to obtain trans olefins;

[0024] The post-treatment comprises cooling to room temperature, adding saturated saline, extracting with an extractant, drying the organic phase, concentrating under reduced pressure, and separating and purifying;

[0025] The extractant is ethyl acetate;

[0026] When drying, the desiccant used is anhydrous sodium sulfate;

[0027] When performing separation and purification, the separation and purification method used is column chromatography separation and purification.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention provides a metal-free catalytic method based on the S / organic solvent / H2O system, using elemental sulfur (S8) as a catalyst precursor, water and an organic solvent as a hydrogen source and solvent, to achieve efficient semi-reduction of alkynes to highly selective trans-olefins. The method of the present invention has the advantages of being environmentally friendly, low cost, having a wide range of substrate applicability, being simple to operate, and having broad prospects for industrial application. Specifically, the method adopts elemental sulfur as a catalyst precursor, avoiding the use of traditional transition metal catalysts, thereby reducing the problem of metal residue pollution, and conforming to the development trend of green chemistry. Elemental sulfur is a natural, non-toxic, and inexpensive reagent. Compared with expensive transition metal catalysts, the catalytic system of the present invention significantly reduces production costs. The method of the present invention is not only applicable to simple diphenylacetylene, but also to a variety of aromatic alkynes containing different substituents, as shown in Examples 22 to 36, showing a wide range of substrate applicability and good functional group tolerance. The reaction conditions of the present invention are mild, the operation is relatively simple, and complex equipment and harsh reaction conditions are not required, which is conducive to industrial application. Since the present invention solves the problems of high cost and heavy pollution existing in traditional transition metal catalytic systems and realizes the preparation of trans-olefins with high selectivity and high yield, it has broad prospects for industrial application.

[0030] (2) The method of the present invention for the semi-reduction selective synthesis of trans-olefins by diaryl alkynes catalyzed by elemental sulfur can achieve a maximum yield of 93% in the synthesis of trans-stilbene. The method of the present invention is also applicable to the semi-reduction selective synthesis of trans-olefins using 2-(phenylethynyl)naphthalene, 1-methyl-3-(phenylethynyl)benzene, 1-methyl-4-(phenylethynyl)benzene, 1-methyl-2-(phenylethynyl)benzene, ‌4-(phenylethynyl)-1,1'-biphenyl, 1-ethyl-4-(phenylethynyl)benzene, 1-tert-butyl-4-(phenylethynyl)benzene, 1-methoxy-4-(phenylethynyl)benzene, ‌1-fluoro-4-(phenylethynyl)benzene, 1-chloro-4-(phenylethynyl)benzene, ‌1-bromo-4-(phenylethynyl)benzene, and ‌1-trifluoromethyl-4-(phenylethynyl)benzene as raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the H NMR spectrum of the product trans-diphenylethylene obtained in Example 1;

[0032] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 22;

[0033] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 23;

[0034] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 24;

[0035] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 25;

[0036] Figure 6 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 26;

[0037] Figure 7 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 27;

[0038] Figure 8 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 28;

[0039] Figure 9 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 29;

[0040] Figure 10 is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 30;

[0041] Figure 11 is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 31;

[0042] Figure 12 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 32;

[0043] Figure 13 This is the hydrogen nuclear magnetic resonance spectrum of the product obtained in Example 33. DETAILED DESCRIPTION

[0044] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described.

[0045] The elemental sulfur used in Examples 1-33 was sulfur powder.

[0046] Example 1

[0047] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of N,N-dimethylformamide (DMF) were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 93%.

[0048] Figure 1 The H NMR spectrum of the product trans-diphenylethylene obtained in this example is shown in FIG. Figure 1 It can be seen that the product structure is correct.

[0049] The specific H NMR spectrum data are as follows:

[0050] 1 H-NMR (400MHz, CDCl3) δ7.44(d,J=7.4Hz,4H), 7.28(t,J=7.3Hz,4H), 7.24–7.12(m,2H), 7.03(s,2H).

[0051] Example 2

[0052] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of N-methylformamide were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 85%.

[0053] Example 3

[0054] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of N,N-dimethylaniline were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 14%.

[0055] Example 4

[0056] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of triethylamine were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 2%.

[0057] Example 5

[0058] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of ethanolamine were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 70%.

[0059] Example 6

[0060] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of n-butylamine were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 9%.

[0061] Example 7

[0062] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of dimethyl sulfoxide (DMSO) were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 2%.

[0063] Example 8

[0064] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of pyridine were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 2%.

[0065] Example 9

[0066] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of N-methylpyrrolidone were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 7%.

[0067] Example 10

[0068] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 6 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 58%.

[0069] Example 11

[0070] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 8 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 83%.

[0071] Example 12

[0072] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 10 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 86%.

[0073] Example 13

[0074] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 13 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 93%.

[0075] It can be seen from the results of Examples 1-13 that the solvent and reaction time have a great influence on the reaction. When DMF is used as the solvent, the best result is obtained when the reaction is carried out for 12 hours.

[0076] Example 14

[0077] Under N2 protection, 0.25 mmol of diphenylacetylene, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography. The yield of trans-diphenylethylene was 0%.

[0078] Example 15

[0079] Under N2 protection, 0.25 mmol of diphenylacetylene, 0.5 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 43%.

[0080] Example 16

[0081] Under N2 protection, 0.25 mmol of diphenylacetylene, 0.75 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 140°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 84%.

[0082] It can be seen from Example 1 and Examples 14-16 that the molar ratio of elemental sulfur to diphenylacetylene has a significant effect on the reaction, and the optimal molar ratio of elemental sulfur to diphenylacetylene is 4:1.

[0083] Example 17

[0084] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 100°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 8%.

[0085] Example 18

[0086] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 120°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 84%.

[0087] Example 19

[0088] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 130°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 89%.

[0089] Example 20

[0090] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a thick-walled pressure-resistant bottle, the bottle cap was tightened, and the reaction was carried out at 150°C with stirring for 12 h. After the reaction was completed, it was cooled to room temperature, 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure, and then separated and purified by column chromatography to obtain trans-diphenylethylene, which was a white solid with a calculated yield of 86%.

[0091] It can be seen from Example 1 and Examples 17-20 that the reaction temperature has a significant effect on the reaction, and the optimal reaction temperature is 140°C.

[0092] Example 21

[0093] Under N2 protection, 0.25 mmol of diphenylacetylene, 1 mmol of elemental sulfur, 27 μL of water and 1 mL of DMF were added to a two-necked flask equipped with a condenser. The mixture was stirred at 140°C for 12 h. After the reaction was completed, it was cooled to room temperature. 10 mL of saturated brine was added to the system, and extraction was carried out with 10 mL of ethyl acetate. The obtained organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. After separation and purification by column chromatography, trans-diphenylethylene was obtained as a white solid with a calculated yield of 23%.

[0094] It can be seen from Example 1 and Example 21 that closed conditions are the best choice for this reaction.

[0095] Example 22

[0096] Under nitrogen protection, 0.25 mmol of 2-(phenylethynyl)naphthalene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the mixture was cooled to room temperature and 10 mL of saturated brine was added. Extraction was performed with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The product was obtained as a white solid with a calculated yield of 86%. The structural formula of the product is as follows:

[0097]

[0098] Figure 2 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 2 It can be seen that the product structure is correct.

[0099] The specific H NMR spectrum data are as follows:

[0100] 1 H NMR(400MHz, CDCl3) δ7.89–7.78(m,4H), 7.74(d,J=8.5Hz,1H), 7.56(d, J=7.4Hz,2H), 7.50–7.41(m,2H),7.38(t,J=7.2Hz,2H), 7.27 (dd,J=12.1,6.5Hz,3H).

[0101] Example 23

[0102] Under N2 protection, 0.25 mmol of 1-methyl-3-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and 10 mL of saturated brine was added. Extraction was performed with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The product was obtained as a white solid with a calculated yield of 62%. The structural formula of the product is as follows:

[0103]

[0104] Figure 3 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 3 It can be seen that the product structure is correct.

[0105] The specific H NMR spectrum data are as follows:

[0106] 1 H NMR (400MHz, CDCl3) δ7.50(d,J=7.5Hz,2H), 7.33(dd, J=15.8,8.5Hz,4H),7.24(t,J=7.9Hz,2H),7.12–6.99(m,3H), 2.37(s,3H).

[0107] Example 24

[0108] Under N2 protection, 0.25 mmol of 1-methyl-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and 10 mL of saturated brine was added. Extraction was performed with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The product was obtained as a white solid with a calculated yield of 89%. The structural formula of the product is as follows:

[0109]

[0110] Figure 4 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 4 It can be seen that the product structure is correct.

[0111] The specific H NMR spectrum data are as follows:

[0112] 1H NMR (400MHz, CDCl3) δ7.50(d,J=7.6Hz,2H), 7.41(d,J=7.4Hz,2H), 7.35(t,J=7.4Hz,2H), 7.24(t,J=7.3Hz,1H), 7.17(d,J=7.6Hz,2H), 7.13–7.00 (m,2H), 2.36(s,3H).

[0113] Example 25

[0114] Under N2 protection, 0.25 mmol of 1-methyl-2-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, it was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The substance was a white solid with a calculated yield of 80%. The structural formula of the product is as follows:

[0115]

[0116] Figure 5 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 5 It can be seen that the product structure is correct.

[0117] The specific H NMR spectrum data are as follows:

[0118] 1 H NMR(400MHz, CDCl3) δ7.51(d,J=7.6Hz,2H), 7.46–7.31(m,4H), 7.29–7.21(m,2H), 7.16(t,J=11.9Hz,2H), 7.06(d,J=17.4Hz,2H), 2.36(d,J=15.6Hz,3H).

[0119] Example 26

[0120] Under N2 protection, 0.25 mmol of ‌4-(phenylethynyl)-1,1'-biphenyl, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the reaction was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The product was purified by column chromatography to obtain the pure product as a white solid with a calculated yield of 83%. The structural formula of the product is:

[0121]

[0122] Figure 6 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 6 It can be seen that the product structure is correct.

[0123] The specific H NMR spectrum data are as follows:

[0124] 1 H NMR (400MHz, CDCl3) δ7.60(q,J=8.0Hz,6H), 7.53(d,J=7.5Hz,2H), 7.44(t,J=7.3Hz,2H), 7.35(q,J=8.0Hz,3H),7.29–7.23(m,1H), 7.15(s,2H).

[0125] Example 27

[0126] Under N2 protection, 0.25 mmol of 1-ethyl-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, it was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The substance was a white solid with a calculated yield of 80%. The structural formula of the product is:

[0127]

[0128] Figure 7 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 7 It can be seen that the product structure is correct.

[0129] The specific H NMR spectrum data are as follows:

[0130] 1 H NMR(400MHz, CDCl3) δ7.50(d,J=7.5Hz, 2H), 7.44(d,J=7.5Hz,2H), 7.35(t,J=7.4Hz,2H), 7.23(dt,J=15.7,8.1Hz,3H), 7.16–7.01(m,2H), 2.66(q,J=7.5Hz,2H),1.25(t,J=7.5Hz,3H).

[0131] Example 28

[0132] Under N2 protection, 0.25 mmol of 1-tert-butyl-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, it was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The substance was a white solid with a calculated yield of 68%. The structural formula of the product is:

[0133]

[0134] Figure 8 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 8 It can be seen that the product structure is correct.

[0135] The specific H NMR spectrum data are as follows:

[0136] 1 H NMR (400MHz, CDCl3) δ7.51(d,J=7.4Hz,2H), 7.46(d,J=7.5Hz,2H), 7.36(dd,J=17.1,8.1Hz,4H), 7.24(t,J=7.2Hz,1H), 7.14–7.02(m,2H).

[0137] Example 29

[0138] Under N2 protection, 0.25 mmol of 1-methoxy-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After the reaction was completed, it was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The substance was a white solid with a calculated yield of 59%. The structural formula of the product is:

[0139]

[0140] Figure 9 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 9 It can be seen that the product structure is correct.

[0141] The specific H NMR spectrum data are as follows:

[0142] 1H NMR(400 MHz, CDCl3) δ7.39(dd,J=14.3,7.7Hz,4H), 7.26(t,J=7.4Hz,2H),7.15(t,J=7.2Hz,1H), 6.99(d,J=16.2Hz,1H),6.89(d,J=16.3Hz,1H), 6.82(d,J=7.8Hz,2H), 3.74(s,3H).

[0143] Example 30

[0144] Under nitrogen protection, 0.25 mmol of ‌1-fluoro-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the reaction was cooled to room temperature and 10 mL of saturated brine was added. Extraction was performed with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The pure product was separated and purified by column chromatography. The product was obtained as a white solid with a calculated yield of 86%. The structural formula of the product is:

[0145]

[0146] Figure 10 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 10 It can be seen that the product structure is correct.

[0147] The specific H NMR spectrum data are as follows:

[0148] 1 H NMR (400MHz, CDCl3) δ7.49(t,J=9.1Hz,4H),7.36(t,J=7.3Hz,2H), 7.27(d,J=8.8Hz,2H), 7.12–6.98(m,4H).

[0149] Example 31

[0150] Under N2 protection, 0.25 mmol of ‌1-chloro-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the reaction was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The product was purified by column chromatography to obtain the pure product as a white solid with a calculated yield of 83%. The structural formula of the product is:

[0151]

[0152] Figure 11 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 11 It can be seen that the product structure is correct.

[0153] The specific H NMR spectrum data are as follows:

[0154] 1 H NMR (400MHz, CDCl3) δ7.49(d,J=7.5Hz,2H), 7.42(d,J=7.7Hz,2H), 7.31(ddd,J=23.8,15.3,7.8Hz,5H), 7.11–6.99(m,2H).

[0155] Example 32

[0156] Under nitrogen protection, 0.25 mmol of ‌1-bromo-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the reaction was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The product was purified by column chromatography to obtain the pure product as a white solid with a calculated yield of 79%. The structural formula of the product is:

[0157]

[0158] Figure 12 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 12 It can be seen that the product structure is correct.

[0159] The specific H NMR spectrum data are as follows:

[0160] 1 H NMR (400MHz, CDCl3) δ7.55–7.45(m,4H), 7.37(t,J=7.9Hz,4H), 7.31–7.25(m,1H), 7.07(q,J=16.3Hz,2H).

[0161] Example 33

[0162] Under N2 protection, 0.25 mmol of ‌1-trifluoromethyl-4-(phenylethynyl)benzene, 1 mmol of elemental sulfur, 27 μL of water, and 1 mL of DMF were added to a thick-walled pressure-resistant bottle. The bottle cap was tightened and the reaction was stirred at 140°C for 12 hours. After completion of the reaction, the reaction was cooled to room temperature. 10 mL of saturated brine was added to the system and extracted with 10 mL of ethyl acetate. The resulting organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The product was purified by column chromatography to obtain the pure product as a white solid with a calculated yield of 50%. The structural formula of the product is:

[0163]

[0164] Figure 13 The H NMR spectrum of the product obtained in this example is shown in FIG. Figure 13 It can be seen that the product structure is correct.

[0165] The specific H NMR spectrum data are as follows:

[0166] 1 H NMR (400MHz, CDCl3) δ7.61(s,4H), 7.54(d,J=7.5Hz,2H), 7.39(t,J=7.2Hz,2H), 7.34–7.28(m,1H),7.16(q,J=16.2Hz,2H).

[0167] Regarding the purity of the product in Example 1-33, since the purity has reached more than 99% and close to 100% after separation and purification by column chromatography, the effect of purity on the yield was not considered when calculating the yield.

Claims

1. A method for selectively synthesizing trans-olefins by semi-reduction of diaryl alkynes catalyzed by elemental sulfur, characterized in that: Under the protection of inert gas, diaryl alkynes, elemental sulfur, water and organic solvent are mixed and subjected to a semi-reductive selective synthesis reaction to obtain trans-olefins; The molar ratio of diaryl alkyne to elemental sulfur is 1:2-4; The ratio of diaryl alkyne to water is 0.25 mmol: 25-30 μL; The ratio of diaryl alkyne to organic solvent is 0.25mmol:0.8-1.2mL; The semi-reductive selective synthesis reaction is carried out in a closed environment.

2. The method for selectively synthesizing trans-olefins by semi-reduction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: The diaryl alkyne is one of diphenyl acetylene, 2-(phenylethynyl)naphthalene, 1-methyl-3-(phenylethynyl)benzene, 1-methyl-4-(phenylethynyl)benzene, 1-methyl-2-(phenylethynyl)benzene, ‌4-(phenylethynyl)-1,1'-biphenyl, 1-ethyl-4-(phenylethynyl)benzene, 1-tert-butyl-4-(phenylethynyl)benzene, 1-methoxy-4-(phenylethynyl)benzene, ‌1-fluoro-4-(phenylethynyl)benzene, 1-chloro-4-(phenylethynyl)benzene, ‌1-bromo-4-(phenylethynyl)benzene, and ‌1-trifluoromethyl-4-(phenylethynyl)benzene.

3. The method for selectively synthesizing trans-olefins by semi-reduction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: The organic solvent is one of N,N-dimethylformamide, N-methylformamide, N,N-dimethylaniline, triethylamine, ethanolamine, n-butylamine, dimethyl sulfoxide, pyridine, and N-methylpyrrolidone.

4. The method for selectively synthesizing trans-olefins by semi-reductive reaction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: The inert gas is nitrogen.

5. The method for selectively synthesizing trans-olefins by semi-reductive reaction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: The temperature of the semi-reductive selective synthesis reaction is 100-150° C., and the time is 6-13 hours.

6. The method for selectively synthesizing trans-olefins by semi-reductive reaction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: The semi-reduction selective synthesis reaction is carried out under stirring conditions.

7. The method for selectively synthesizing trans-olefins by semi-reductive reaction of diaryl alkynes catalyzed by elemental sulfur according to claim 1, characterized in that: After the semi-reductive selective synthesis reaction is completed, post-treatment is performed to obtain trans olefins.

8. The method for selectively synthesizing trans-olefins from diaryl alkynes catalyzed by elemental sulfur according to claim 7, characterized in that: The post-treatment comprises cooling to room temperature, adding saturated saline, extracting with an extractant, drying the organic phase, concentrating under reduced pressure, and separating and purifying.

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