A method for synthesizing dithiocyclic carbonates

Abstract

The present invention discloses a method for synthesizing dithiocyclic carbonates, belonging to the technical field of organic catalysis. By using a brand-new organic neutral catalyst, the [3+2] cycloaddition reaction of epoxides and carbon disulfide can be achieved at room temperature within a short time, and dithiocyclic carbonates can be obtained with high selectivity. This catalytic system has excellent catalytic effects on different aliphatic and aromatic epoxides, and the yields of most of them reach over 90%. The dithiocyclic carbonate products have no metal residues and have great potential for commercial applications in fields such as biomedicine and polymer production where strict requirements are imposed on the content of metal residues.

Description

Technical Field

[0001] The present invention belongs to the technical field of organocatalysis, and particularly relates to a method for synthesizing dithiocyclic carbonates. Background Art

[0002] Dithiocyclic carbonates are a class of five-membered heterocyclic compounds containing both oxygen and sulfur elements. This class of compounds has attracted much attention due to their radiation protection effect and application in polymer synthesis. In recent years, this class of compounds has also been applied to a battery adhesive with self-healing function (CN113224309B). This compound was first reported in 1968 (US3409635A), and the method in this patent was to prepare dithiocyclic carbonates through the cycloaddition reaction of epoxides and carbon disulfide. And a patent published in the same year introduced the preparation of sulfur-containing polymers from dithiocyclic carbonates as polymer monomers (US4618461A). To date, the [3+2] cycloaddition reaction of epoxides and carbon disulfide to prepare dithiocyclic carbonates is still the most direct and effective method (as shown in the figure below). The starting materials for this reaction, epoxides and carbon disulfide, are both bulk chemicals with high production and low prices in China. Considering economic and environmental protection aspects, this process has atom economy and conforms to the concept of green chemistry, undoubtedly having greater advantages and attractiveness. Even from the perspective of industrial production, it is very promising to use high-energy raw materials to prepare high-value-added products. To date, there are few reports on the synthesis research of this compound in domestic patents.

[0003]

[0004] In the above formula, R represents each fatty alkyl group, aromatic alkane, and glycidyl ether.

[0005] Since the bond length of the C=S bond in sulfur dioxide is 155.26 pm, and that of its homolog carbon dioxide is 116 pm, the longer C=S bond means higher activity and reaction potential energy. Under harsh conditions such as high temperature, high pressure, and high catalyst loading, it is extremely easy to have frequent oxygen / sulfur exchange with epoxides. In addition to the target product dithiocyclic carbonate, by-products such as trithiocyclic carbonate, regioisomers, and thiirane will also be generated, which leads to the uncontrollability of this reaction and low overall yield (J. Org. Chem. 1995, 60, 473). Based on the above research, many new catalysts have been developed by researchers to solve this problem, including alkali metal hydrides (Synlett, 2008, 6, 889), metal alkyl salts (ChemCatChem, 2016, 8, 2027), metal chlorides (Applied Catalysis, B: Environmental, 2019, 254, 380), organometallic complexes (Synlett, 2010, 4, 623; ChemCatChem, 2014, 6, 1252), N-heterocyclic carbenes, Brønsted bases (Bulletin of the Chemical Society of Japan, 1988, 61, 921), etc. Through continuous optimization, these catalysts have alleviated the pain point of complex by-products in this reaction to a certain extent and can obtain dithiocyclic carbonate with high selectivity. However, there are still problems such as harsh reaction conditions, high catalyst loading, complex catalyst preparation process, and introduction of metal residues. These disadvantages limit the industrial production and further application of dithiocyclic carbonate products.

[0006] Starting from the mechanism of this reaction, we believe that the fundamental problem of inhibiting oxygen / sulfur exchange lies in appropriately weakening the activity of the reaction intermediate sulfur anion, which requires an electron-deficient Lewis acid center to stabilize the active sulfur anion. Similar to the principle of coordinated metals, we believe that hydrogen bond coordination can also achieve this goal. The hydrogen bond is essentially a non-covalent chemical bond, which has been developed in the field of organic small molecule synthesis by the research of Jacobsen and his colleagues. Currently, hydrogen bond catalysis has become a common means in organic synthesis. Hydrogen bond catalysis is essentially Brønsted acid catalysis. By coordinating the polar hydrogen nucleus with atoms containing lone pairs of electrons and high electronegativity, the substrate can be activated to be more easily attacked by nucleophiles. At the same time, the hydrogen bond can stabilize the sulfur anion in the reaction process to achieve high controllability. Based on the above background, we designed an organic catalyst containing a hydrogen bond donor, namely cyclopropenium ion pair, which can provide both a hydrogen bond donor to activate the monomer and a halogen anion to nucleophilically attack the ring opening of the epoxide. Summary of the Invention

[0007] The object of the present invention is to provide a method for synthesizing dithiocyclic carbonates. By using a novel organic neutral catalyst, the [3+2] cycloaddition reaction of epoxides with carbon disulfide can be achieved at room temperature within a short time (6 hours), and dithiocyclic carbonates can be obtained with high selectivity. This catalytic system has excellent catalytic effects on different aliphatic and aromatic epoxides, and the yields of most of them reach more than 90%. The dithiocyclic carbonate products have no metal residues and have great potential for commercial applications in fields such as biomedicine and polymer production where strict requirements are imposed on the content of metal residues.

[0008] The present invention first proposes to use a bifunctional organic catalyst of multiple hydrogen bond donors (HBDs) and nucleophilic halogen ions (X – ) to generate dithiocyclic carbonates from epoxides and carbon disulfide. The target catalyst can be obtained by a one-step reaction of commercially available pentachlorocyclopropane with readily available secondary amines. The steps are simple, the purification is convenient, and the yield is high. The crude reaction mixture can be directly dried after extraction without post-treatment such as column chromatography.

[0009] In order to expand the applications of dithiocyclic carbonates in fields such as biomedicine, polymer synthesis, and radiation protection, the present invention discovers and solves problems from actual demands, and uses a bifunctional cyclopropenium ion pair as a hydrogen bond donor and a nucleophilic halogen ion to catalytically synthesize dithiocyclic carbonates with various aliphatic or aromatic substituents. This organic molecular catalytic system is first proposed for use in the coupling reaction of epoxides with carbon disulfide, and can catalytically prepare dithiocyclic carbonates with high yields and high selectivity under mild conditions.

[0010] The technical solution for achieving the above object is as follows:

[0011] A method for synthesizing dithiocyclic carbonates uses the catalyst shown in Formula I to generate dithiocyclic carbonates from the epoxide shown in Formula II and carbon disulfide:

[0012]

[0013] Wherein

[0014] X is selected from Cl, Br or I;

[0015] Wherein R 1 –R 4 is selected from hydrogen, phenyl, methyl, ethyl, butyl, ethanolamine group, cyclohexyl, and R 1 and R 2 are connected to each other to form a cyclic group, and R 3 and R 4 are connected to each other to form a cyclic group, and the cyclic group is a piperidyl group or a morpholinyl group; that is, R 1 , R 2And N are connected to form a piperidyl or a morpholinyl. Similarly, R 3 , R 4 and N form a piperidyl or a morpholinyl together;

[0016] When R 3 and R 4 are connected to form a morpholinyl, R 1 and R 2 are also connected to form a morpholinyl;

[0017] When the substituents of R 3 and R 4 are cyclohexyl, R 1 and R 2 are connected to form a morpholinyl, or R 1 is phenyl, R 2 is ethanolamine group, or R 1 and R 2 are both ethanolamine groups;

[0018] When R 1 –R 4 is selected from methyl, ethyl, butyl, R 1 –R 4 is the same;

[0019] When R 1 and R 3 are selected from hydrogen, R 2 and R 4 are phenyl;

[0020] The epoxide is selected from the structures of Formula II:

[0021]

[0022] R 5 , R 6 are selected from hydrogen, a straight-chain or branched-chain alkyl having 1 to 4 carbon atoms, 1-butenyl, phenyl, a aryl substituted by an alkyl or a halogen, an alkyl substituted by a halogen or R 5 and R 6 are connected to form a cyclohexyl or R 7 –O–CH2, and the said R 7 is selected from phenyl, a phenyl substituted by an alkyl having 1 to 3 carbon atoms, allyl or a straight-chain or branched-chain alkyl having 1 to 4 carbon atoms, allyl glycerol ester.

[0023] Preferably, R 1 –R 4 is selected from methyl, ethyl, ethanolamine group, cyclohexyl, R 1 and R 2 can also be connected to form a cyclic structure, R 3 and R 4It can also be connected to form a cyclic structure, and the cyclic structure is piperidyl or morpholinyl;

[0024] When R 3 and R 4 The substituent is cyclohexyl, R 1 and R 2 are ethanolamine groups;

[0025] When R 1 –R 4 is selected from methyl or ethyl, R 1 and R 2 are the same, and R 3 and R 4 are the same.

[0026] Preferably, the said R 5 and R 6 are selected from hydrogen, 1-butenyl, trifluoromethyl, chloromethyl, aryl or R 7 –O–CH2, and the said R 7 is selected from methyl, aryl, allyl, allyl glycerol ester, tert-butyl.

[0027] Preferably, the catalyst shown in Formula I is selected from the following structures:

[0028]

[0029] Preferably, the epoxide shown in Formula II is selected from phenyl glycidyl ether, m-phenyl glycidyl ether, styrene oxide, 1,1,1-trifluoro-2,3-epoxypropane, epichlorohydrin, 1,2-epoxy-5-hexene, allyl glycidyl ether, methyl glycidyl ether, methyl acrylate glycidyl ether, tert-butyl glycidyl ether, cyclohexene oxide, 2,3-diphenyloxirane.

[0030] The structure of the epoxide is shown in the following table:

[0031]

[0032] The reaction temperature of the said preparation method is 25-80 °C, the molar ratio of the epoxide shown in Formula II to carbon disulfide is 1:1.2-1:8, and the molar ratio of the epoxide shown in Formula II to the catalyst shown in Formula I is 1:0.1-1:0.01.

[0033] Preferably, the reaction temperature of the said preparation method is 25 °C, the ratio of the epoxide shown in Formula II to carbon disulfide is 1:1.2, and the molar ratio of the epoxide shown in Formula II to the catalyst shown in Formula I is 1:0.05.

[0034] Preferably, the specific steps of the said preparation method include:

[0035] (1) Add the epoxide shown in Formula II and the catalyst shown in Formula I to the reaction vessel in a molar ratio of 1:0.05;

[0036] (2) Then add carbon disulfide in a molar amount 1.2 times that of the epoxide shown in Formula II, and then place the reaction vessel at room temperature;

[0037] (3) React for 6 - 12 hours, cool, and obtain the dithiocyclic carbonate from the reaction solution through column chromatography.

[0038] Preferably, the synthesis method of the catalyst shown in Formula I used is: slowly add the organic solution of the corresponding secondary amine to the organic solvent of pentachlorocyclopropane under ice - bath stirring conditions. After the addition is complete, react at room temperature for 24 hours, and obtain the product after extraction and drying.

[0039] Preferably, the solvent in the organic solution of the corresponding secondary amine is dichloromethane, chloroform, ethyl acetate or benzene, and the solvent in the organic solution of pentachlorocyclopropane is dichloromethane, chloroform, ethyl acetate or benzene.

[0040] Beneficial Effects

[0041] (1) Through the above - mentioned catalytic system, the present invention can efficiently synthesize dithiocyclic carbonates with high added value. Compared with the dithiocyclic carbonates synthesized by using metal catalysts and base catalysts in the prior art, it has the characteristics of high selectivity, no metal residue, and mild conditions. It has great potential for commercial applications in fields such as biomedicine, radiation protection, and polymer materials where strict requirements are imposed on metal residues.

[0042] (2) The catalytic system of the present invention catalyzes the [3 + 2] cycloaddition of epoxides and carbon disulfide to synthesize dithiocyclic carbonates through the activation of multiple hydrogen - bond donors (HBDs). There is no domestic patent report on the synthesis of such compounds at present. In addition, there are few patent reports on the organic bifunctional catalytic synthesis of dithiocyclic carbonates. Compared with the synthesis of dithiocyclic carbonates under other conditions such as high temperature, high pressure, long reaction time, and high catalyst loading, the reaction conditions of the present invention are very mild.

[0043] (3) The catalyst used in the present invention is simple to prepare, and has high catalytic conversion rate and selectivity, and is characterized by high efficiency.

[0044] In summary, compared with the existing other catalytic systems, the present invention has obvious advantages such as mildness, high efficiency, easy preparation, and no metal residue. Description of the Drawings

[0045] The embodiments of the present invention will be described in detail in conjunction with the accompanying drawings, where

[0046] Figures 1 to 20: 1H NMR and 13C NMR spectra of the corresponding epoxide products in Examples 1, 9-17

[0047] Figures 21 to 30 : 1H NMR and 13C NMR spectra of the catalysts in Examples 1-5

[0048] Figure 31 : 1H NMR spectrum of the reaction mixture in Example 7 Detailed implementation mode

[0049] The present invention can be further illustrated by the following examples, which are for illustration purposes only and do not limit the present invention. Any ordinary technician in the art can understand that these examples do not limit the present invention in any way and can make appropriate modifications and data transformations without departing from the essence of the present invention and deviating from the scope of the present invention.

[0050] The 1H NMR spectra involved in the examples were measured using a Bruker Ascend TM-400 nuclear magnetic resonance spectrometer from Bruker Corporation. The deuterated reagents used were deuterated chloroform (CDCl3) and deuterated dimethyl sulfoxide (DMSO-d6).

[0051] All raw materials used in the following examples were purchased from Energy Chemical.

[0052] The structure of the catalytic system used in the examples is as follows:

[0053]

[0054] The structure of the epoxides used in the examples is as follows:

[0055]

[0056] Example 1:

[0057] Perform standard Schlenk operation on the reaction flask to remove water and oxygen in the reaction system. Under the condition of passing inert gas, add catalyst 1 (20.5 mg, 0.1 mmol, 0.05 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor on a stirrer with a stirring rate of 400 revolutions per minute for 24 hours. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oily substance, dry it to constant weight, the conversion rate reaches 48%, and the selectivity is 87%. The 1H NMR spectrum of the product is as Figure 1 shown, and the 13C NMR spectrum is as Figure 2As shown. The spectral data are as follows: δ 7.36–7.27 (m, 2H), 7.06–6.99 (m, 1H), 6.99–6.89 (m, 2H), 5.43 (tt, J = 7.7, 4.9 Hz, 1H), 4.30 (qd, J = 10.4, 5.0 Hz, 2H), 3.85–3.68 (m, 2H).

[0058] The preparation method of catalyst 1 is as follows: Perform standard Schlenk operation on the reaction flask to remove water and oxygen in the reaction system. Under the condition of passing inert gas, add N,N-dimethyltrimethylsilylamine (0.78 mL, 4.89 mmol), add 20 mL of dichloromethane, cool the reaction flask to 0 °C, and dropwise add pentachlorocyclopropane (0.21 mL, 1.63 mmol) under stirring. React at room temperature for 24 hours, remove the solution by rotary evaporation, and dry the residue in a vacuum drying oven for 6 hours to obtain a white solid (0.31 g, 94%). The 1H NMR spectrum of the product is as shown in Figure 21 as shown, and the 13C NMR spectrum is as shown in Figure 22 as shown. The spectral data are as follows: 1 H NMR (400 MHz, Chloroform-d) δ 3.19 (s, 18H).

[0059] Example 2:

[0060] Perform standard Schlenk operation on the reaction flask to remove water and oxygen in the reaction system. Under the condition of passing inert gas, add catalyst 2 (23. mg, 0.1 mmol, 0.05 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor on a stirrer with a stirring rate of 400 rpm for 24 hours. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oil, dry it to a constant weight. The conversion rate reaches 40% and the selectivity is 88%.

[0061] The preparation method of catalyst 2 is as follows: Add diethylamine (1.33 mL, 12.9 mmol) to dichloromethane of pentachlorocyclopropane (0.55 mL, 4.3 mmol) and stir for 6 hours, gradually forming a turbid white precipitate. After the solution is extracted with 1M dilute hydrochloric acid solution (3 × 50 mL) and saturated brine (3 × 50 mL), add anhydrous sodium sulfate and dry overnight. Remove the solvent to obtain the pure product. The 1H NMR spectrum of the product is as shown in Figure 23 as shown, and the 13C NMR spectrum is as shown in Figure 24 as shown. The spectral data are as follows: 11H NMR (400 MHz, Chloroform-d) δ 3.41 (q, J = 7.2 Hz, 12H), 1.25 (t, J = 7.2 Hz, 18H).

[0062] Example 3:

[0063] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under an inert gas atmosphere, add catalyst 3 (32.5 mg, 0.1 mmol, 0.05 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor on a stirrer at a stirring rate of 400 revolutions per minute for 24 hours. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil, dry it to a constant weight. The conversion rate reaches 46%, and the selectivity is 88%.

[0064] The preparation method of catalyst 3 is as follows: Add piperidine (1.18 mL, 12.9 mmol) to dichloromethane of pentachlorocyclopropane (0.55 mL, 4.3 mmol), and stir overnight. A turbid white precipitate gradually forms. After the solution is extracted with 1 M dilute hydrochloric acid solution (3 × 50 mL) and saturated brine (3 × 50 mL), add anhydrous sodium sulfate and dry overnight. Remove the solvent to obtain the pure product. The 1H NMR spectrum of the product is as Figure 25 shown, and the 13C NMR spectrum is as Figure 26 shown. The spectral data are: 1 1H NMR (400 MHz, Chloroform-d) δ 3.38 (q, J = 7.3 Hz, 12H), 1.24 (t, J = 7.2 Hz, 18H).

[0065] Example 4:

[0066] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under an inert gas atmosphere, add catalyst 4 (53.8 mg, 0.1 mmol, 0.05 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor on a stirrer at a stirring rate of 400 revolutions per minute for 24 hours. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil, dry it to a constant weight. The conversion rate reaches 67%, and the selectivity is 90%.

[0067] The preparation method of catalyst 4 is as follows: add 100 mL of dichloromethane to a 250 mL reaction bottle, add dicyclohexylamine (11.1 mL, 56 mmol), and slowly add pentachlorocyclopropane (1 mL, 7 mmol) in an ice bath. After reacting for 24 hours, add diethanolamine (1.341 mL, 14 mmol) and continue the reaction for 24 hours. After the reaction is completed, filter the solid, wash it with dichloromethane, and collect the filtrate. Extract the filtrate with 1M dilute hydrochloric acid (100 mL×3) and saturated brine (100 mL×3), collect the organic phase, add anhydrous sodium sulfate, and dry overnight. Remove the solution by rotary evaporation, add ethyl acetate, stir at 60°C for 30 minutes, and filter to obtain pure catalyst 4. The hydrogen spectrum of the product is shown below. Figure 27 As shown, the carbon spectrum is as Figure 28 The spectrum data is: 1 H NMR(400MHz,Chloroform-d)δ3.88(t,J=4.6Hz,4H),3.65(t,J=4.8Hz,4H),3.51(tt,J=12.4,3.5Hz,4H),1.91–1.81(m,1 6H),1.71–1.63(m,4H),1.57(dt,J=12.6,6.1Hz,8H),1.32(dt,J=16.5,13.0Hz,8H),1.12(ddt,J=16.6,13.2,6.6Hz,4H).

[0068] Example 5:

[0069] The reaction flask was subjected to a standard Schlenk procedure to remove water and oxygen from the reaction system. Catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) was added under inert gas. Epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv) were then added. The reaction was allowed to react at room temperature for 24 hours with a stirrer at 400 rpm. After completion of the reaction, the reaction tube was removed and allowed to cool naturally. The resulting mixed solution was purified by column chromatography (petroleum ether:ethyl acetate = 5:1) and dried on a rotary evaporator to obtain a slightly yellow oil. The oil was dried to constant weight, achieving a conversion of 79% and a selectivity of 95%.

[0070] The preparation method of catalyst 5 is as follows: add an acetone solution of catalyst 4 (0.63 g, 1 mmol, 1 eq) to a 100 mL reaction bottle, then add an acetone solution of sodium iodide (0.18 g, 1.2 mmol, 1.2 eq) and stir at room temperature for 2 hours. After filtering the precipitate, add sodium iodide (0.18 g, 1.2 mmol, 1.2 eq) and stir at room temperature for 30 minutes. If no precipitate is formed, the reaction is terminated. The solution is rotary evaporated to obtain a crude product, which is then completely dissolved in dichloromethane. After filtering the precipitate, it is dried to obtain the pure product of catalyst 5. The hydrogen spectrum of the product is shown as follows: Figure 29 As shown, the carbon spectrum is as Figure 30 The spectrum data is: 1 H NMR (400MHz, Chloroform-d) δ4.22(t,J=5.9Hz,2H),3.87(q,J=4.2Hz,4H),3.67(t,J=4.9Hz,4H),3.48(tt,J=12.4,3.7H z,4H),1.96–1.81(m,16H),1.72–1.52(m,12H),1.32(qt,J=13.2,3.3Hz,8H),1.13(dddd,J=16.5,13.0,8.2,3.4Hz,4H).

[0071] Example 6:

[0072] The reaction flask was subjected to a standard Schlenk procedure to remove water and oxygen from the reaction system. Catalyst 5 (12.6 mg, 0.02 mmol, 0.01 equiv) was added under inert gas. Epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv) were then added. The reaction was placed in a preheated reactor at 80°C and stirred at 400 rpm for 24 hours. After the reaction, the reaction tube was removed and allowed to cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), the resulting mixed solution was dried on a rotary evaporator to afford a slightly yellow oil. The oil was dried to constant weight, achieving a conversion of 64% and a selectivity of 91%.

[0073] Example 7:

[0074] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under the condition of passing inert gas, add catalyst 5 (126 mg, 0.2 mmol, 0.10 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor at room temperature for 24 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oil. Dry it to a constant weight. The conversion rate reaches 95%, and the selectivity is 92%. The conversion rate and selectivity are obtained by taking 0.1 mL of the reaction solution after the reaction is completed, preparing a sample and analyzing it using nuclear magnetic resonance hydrogen spectrum. The hydrogen spectrum analysis chart of the mixed solution is shown in Figure 31. 2.75 ppm is the characteristic peak of epoxide A, and 3.75 ppm is the characteristic peak of dithiocyclic carbonate. The reaction conversion rate is 95% obtained from the peak area ratio. 5.00 ppm is the characteristic peak of trithiocyclic carbonate, and 5.44 ppm is the characteristic peak of dithiocyclic carbonate. The selectivity is 92% obtained from the peak area ratio.

[0075] Example 8:

[0076] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under the condition of passing inert gas, add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv). Then add epoxide A (0.24 mL, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor at 40 °C for 24 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oil. Dry it to a constant weight. The conversion rate reaches 92%, and the selectivity is 96%.

[0077] Example 9:

[0078] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under an inert gas atmosphere, add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv). Then add epoxide B (0.328 g, 2 mmol, 1.0 equiv) and carbon disulfide (1 mL, 16 mmol, 8 equiv). React the reactor at 40 °C for 24 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil, dry it to a constant weight. The conversion rate reaches 90%, and the selectivity is 96%. The 1H NMR spectrum of the product is as shown in Figure 3 shown, and the 13C NMR spectrum is as shown in Figure 4 shown. The spectral data are as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 7.18 (t, J = 7.2 Hz, 2H), 6.93 (td, J = 7.4, 1.1 Hz, 1H), 6.84–6.78 (m, 1H), 5.48 (tdd, J = 7.5, 5.0, 4.1 Hz, 1H), 4.36–4.26 (m, 2H), 3.80 (dt, J = 7.5, 3.8 Hz, 2H), 2.25 (s, 3H).

[0079] Example 10:

[0080] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under an inert gas atmosphere, add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv). Then add epoxide C (0.24 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 6 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil, dry it to a constant weight. The conversion rate reaches 92%, and the selectivity is 98%. The 1H NMR spectrum of the product is as shown in Figure 5 shown, and the 13C NMR spectrum is as shown in Figure 6 shown. The spectral data are as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 7.53–7.47 (m, 2H), 7.47–7.29 (m, 3H), 5.64 (dd, J = 10.4, 5.7 Hz, 1H), 4.13–3.99 (m, 2H).

[0081] Example 11:

[0082] Carry out standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under the condition of passing inert gas, add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv). Then add epoxide D (0.224 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 6 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oily substance, dry it to constant weight, with a conversion rate of 91% and a selectivity of 97%. The 1H NMR spectrum of the product is as Figure 7 shown, and the 13C NMR spectrum is as Figure 8 shown. The spectral data are as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 5.34 (tq, J = 7.8, 5.8 Hz, 1H), 3.89–3.78 (m, 2H).

[0083] Example 12:

[0084] Carry out standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Under the condition of passing inert gas, add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv). Then add epoxide E (0.185 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 12 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oily substance, dry it to constant weight, with a conversion rate of 91% and a selectivity of 96%. The 1H NMR spectrum of the product is as Figure 9 shown, and the 13C NMR spectrum is as Figure 10 shown. The spectral data are as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 5.38–5.26 (m, 1H), 3.85 (dd, J = 5.8, 3.1 Hz, 2H), 3.77–3.68 (m, 2H).

[0085] Example 13:

[0086] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) under an inert gas atmosphere. Then add epoxide F (0.196 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 6 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil. Dry it to a constant weight. The conversion rate reaches 92%, and the selectivity is 97%. The 1H NMR spectrum of the product is as shown in Figure 11 shown, and the 13C NMR spectrum is as shown in Figure 12 shown. The spectral data are as follows: 1 1H NMR (400 MHz, Chloroform-d) δ 5.92–5.71 (m, 1H), 5.16–4.97 (m, 3H), 3.59 (dd, J = 11.0, 6.5 Hz, 1H), 3.44–3.35 (m, 1H), 2.28 (dddt, J = 14.7, 9.4, 8.0, 4.1 Hz, 2H), 2.14 (dtd, J = 14.2, 7.8, 6.3 Hz, 1H), 1.90 (dddd, J = 14.1, 8.7, 6.7, 5.4 Hz, 1H).

[0087] Example 14:

[0088] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) under an inert gas atmosphere. Then add epoxide G (0.228 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 6 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether: ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellowish oil. Dry it to a constant weight. The conversion rate reaches 92%, and the selectivity is 92%. The 1H NMR spectrum of the product is as shown in Figure 13 shown, and the 13C NMR spectrum is as shown in Figure 14 shown. The spectral data are as follows: 1HNMR (400 MHz, Chloroform-d) δ 5.88 (ddt, J=17.3, 10.4, 5.7 Hz, 1H), 5.34–5.16 (m, 3H), 4.07 (dt, J=5.9, 1.5 Hz, 2H), 3.83–3.72 (m, 2H), 3.69 (dd, J=11.1, 8.3 Hz, 1H), 3.61 (dd, J=11.1, 7.2 Hz, 1H).

[0089] Example 15:

[0090] The reaction flask was subjected to standard Schlenk operation to remove water and oxygen from the reaction system. Under an inert gas atmosphere, catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) was added. Then, epoxide H (0.196 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv) were added. The reactor was reacted at room temperature for 6 hours on a stirrer with a stirring rate of 400 rpm. After the reaction was completed, the reaction tube was taken out and allowed to cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution was obtained. It was dried by rotary evaporation to obtain a slightly yellow oil, dried to a constant weight, with a conversion rate of 89% and a selectivity of 94%. The 1H NMR spectrum of the product is as Figure 15 shown, and the 13C NMR spectrum is as Figure 16 shown. The spectral data are as follows: 1 HNMR (400 MHz, Chloroform-d) δ 5.21 (ddt, J=8.5, 7.2, 4.7 Hz, 1H), 3.76 (dd, J=10.9, 4.8 Hz, 1H), 3.71–3.63 (m, 2H), 3.58 (dd, J=11.1, 7.2 Hz, 1H), 3.42 (s, 3H).

[0091] Example 16:

[0092] The reaction flask was subjected to standard Schlenk operation to remove water and oxygen from the reaction system. Under an inert gas atmosphere, catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) was added. Then, epoxide I (0.284 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv) were added. The reactor was reacted at room temperature for 6 hours on a stirrer with a stirring rate of 400 rpm. After the reaction was completed, the reaction tube was taken out and allowed to cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution was obtained. It was dried by rotary evaporation to obtain a slightly yellow oil, dried to a constant weight, with a conversion rate of 89% and a selectivity of 91%. The 1H NMR spectrum of the product is as Figure 17As shown, the carbon spectrum is as follows Figure 18 As shown. The spectrum data are as follows: 1 HNMR(400MHz,Chloroform-d)δ6.17(q,J=1.2Hz,1H),5.65(h,J=1.9Hz,1H),5.38(tt,J=7.7,4.5Hz,1H),4.49(qd,J=12.4,4.5Hz,2H),3.71(dd,J=11.2,7.4Hz,1H),3.57(dd,J=11.2,8.0Hz,1H).

[0093] Example 17:

[0094] Perform standard Schlenk operation on the reaction flask to remove water and oxygen from the reaction system. Add catalyst 5 (24.6 mg, 0.1 mmol, 0.02 equiv) under an inert gas atmosphere. Then add epoxide J (0.260 g, 2 mmol, 1.0 equiv) and carbon disulfide (0.14 mL, 4 mmol, 1.2 equiv). React the reactor at room temperature for 6 hours on a stirrer with a stirring rate of 400 revolutions per minute. After the reaction is completed, take out the reaction tube and let it cool naturally. After column chromatography (petroleum ether:ethyl acetate = 5:1), a mixed solution is obtained. Spin-dry it on a rotary evaporator to obtain a slightly yellow oily substance, dry it to a constant weight. The conversion rate reaches 97% and the selectivity is 89%. The hydrogen spectrum of the product is as follows Figure 19 As shown, the carbon spectrum is as follows Figure 20 As shown. The spectrum data are as follows: 1 HNMR(400MHz,Chloroform-d)δ5.18(tt,J=7.4,5.3Hz,1H),3.68(d,J=5.3Hz,2H),3.63(t,J=7.6Hz,2H),1.19(s,9H).

Claims

1. A method for synthesizing dithiocyclic carbonate, characterized in that, Using the catalyst shown in Formula I, a dithiocyclic carbonate is formed from an epoxide shown in Formula II and carbon disulfide: wherein X is selected from Cl, Br or I; wherein R 1 –R 4 is selected from hydrogen, methyl, ethyl, butyl, ethanolamine group, cyclohexyl, R 1 and R 2 may also be connected to form a cyclic structure, R 3 and R 4 may also be connected to form a cyclic structure, and the cyclic structure is piperidyl, morpholinyl; When R 3 and R 4 are connected to form a morpholino group, R 1 and R 2 are also connected to form a morpholino group; When R 3 and R 4 are cyclohexyl substituents, R 1 and R 2 are joined to form a morpholino group, or both R 1 and R 2 are 2-aminoethylamino groups; When R 1 –R 4 is selected from methyl, ethyl, butyl, R 1 -R 4 is the same; the epoxide described is selected from the structure of Formula II: R 5 and R 6 is selected from hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, 1-butenyl, phenyl or R 5 and R 6 are connected to form cyclohexyl or R 7 -O-CH2, and the R 7 is selected from phenyl, phenyl substituted by an alkyl group having 1 to 3 carbon atoms, allyl or a linear or branched alkyl group having 1 to 4 carbon atoms, allyl glycerol ester.

2. The method according to claim 1, characterized in that, wherein R 1 -R 4 is selected from methyl, ethyl, ethanolamine group, cyclohexyl, R 1 and R 2 may also be connected to form a cyclic structure, R 3 and R 4 may also be connected to form a cyclic structure, and the cyclic structure is piperidyl, morpholinyl; When R 3 and R 4 substituents are cyclohexyl groups, R 1 and R 2 are ethanolamine groups; When R 1 -R 4 is selected from methyl and ethyl, R 1 -R 4 is the same.

3. The method according to claim 1, wherein The described R 5 and R 6 are selected from hydrogen, 1-butenyl, trifluoromethyl, chloromethyl or R 7 -O-CH2, and the described R 7 is selected from methyl, allyl, allyl glycerol ester, tert-butyl.

4. The method according to claim 1, wherein The catalyst shown in Formula I has the following structure 5. The method according to claim 1, wherein The epoxide shown in Formula II has the following structure 6. The method according to claim 1, wherein The reaction temperature of the preparation method is 25 to 80 °C, the molar ratio of the epoxide shown in Formula II to carbon disulfide is 1:1.2 to 1:8, and the molar ratio of the epoxide shown in Formula II to the catalyst shown in Formula I is 1:0.1 to 1:0.

01.

7. The method according to claim 1, wherein The reaction temperature of the preparation method is 25 °C, the ratio of the epoxide shown in Formula II to carbon disulfide is 1:1.2, and the molar ratio of the epoxide shown in Formula II to the catalyst shown in Formula I is 1:0.

05.

8. The method according to claim 1, characterized in that, The specific steps of the described preparation method include: (1) Add the epoxide shown in Formula II and the catalyst shown in Formula I into a reaction vessel in a molar ratio of 1:0.05; (2) Then add carbon disulfide in a molar amount 1.2 times that of the epoxide shown in Formula II, and then place the reaction vessel at room temperature; (3) React for 6 to 12 hours, cool, and obtain the dithiocyclic carbonate from the reaction solution by column chromatography.

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