Method for producing 2-oxazolidinones using silica catalyst

Abstract

To provide a method of producing a 2-oxazolidinone useful as a medical and agrochemical intermediate by using an inexpensive and reusable catalyst.SOLUTION: The invention provides a method of producing a 2-oxazolidinone represented by the general formula (II) by reacting carbon dioxide with a propargylamine represented by the general formula (I) in the presence of a catalyst containing silica as an active ingredient. Preferably, the silica is mesoporous silica, or silica-coated magnetic nanoparticles. (In the formulas, R1, R2, R3 and R4 each represent H, or a C1-20 substituent optionally containing a nitrogen atom, oxygen atom, sulfur atom or halogen atom.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present application relates to a method for producing 2-oxazolidinones using a silica catalyst. [Background technology]

[0002] 2-Oxazolidinones are known to be useful as intermediates for medicines and agricultural chemicals such as antibiotics and furaltadone. Carbon dioxide is non-toxic and inexpensive. For this reason, there is a demand for the synthesis of 2-oxazolidinones using carbon dioxide. For example, a method for producing 2-oxazolidinones using carbon dioxide as a carbon source, a transition metal complex as a catalyst, and propargylamines as a raw material has been reported (see Non-Patent Documents 1-3).

[0003] Also, a method for producing 2-oxazolidinones using an organic catalyst such as a strong base to reduce the use of heavy metals has been reported (see Non-Patent Document 4). In recent years, from the perspective of green chemistry, recovery and reuse (recycling) of catalysts has been required. A method for producing 2-oxazolidinones using propargylamines as a raw material by activating carbon dioxide using a silica-immobilized base catalyst has been reported, and after the reaction is completed, the catalyst is recovered by filtering the reaction solution, making it possible to reuse the catalyst (see Non-Patent Document 5).

[0004] Recently, a method for producing 2-oxazolidinones using a gold(I) complex catalyst immobilized on magnetite-containing silica has also been reported. In this method, after the reaction is completed, a magnet is brought close to the reaction vessel to attract the catalyst, the reaction solution is removed by decantation, and the reaction substrate is added to the reaction vessel, so that the catalyst can be reused without filtration (see Non-Patent Document 6). However, solid support-immobilized catalysts are often synthesized in multiple steps, and therefore their synthesis is not easy. In addition, catalysts containing precious metals are expensive, so the emergence of inexpensive catalysts is desired. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Bulletin of the Chemical Society of Japan (Bull. Chem. Soc. Jpn), 2011, Vol. 84, p. 698 [Non-Patent Document 2] "Organometallics", 2013, Vol. 32, p. 5285 [Non-Patent Document 3] "Tetrahedron", 2016, Vol. 72, p.1205 [Non-Patent Document 4] "J. Chem. Soc., Perkin Trans. 1", 1998, p.1541 [Non-Patent Document 5] Tetrahedron Lett., 2007, Vol. 48, p. 2131 [Non-Patent Document 6] Appl. Organometal. Chem., 2016, Vol. 30, p. 835 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present application is to provide a novel process for producing 2-oxazolidinones using a catalyst that is inexpensively available and reusable. [Means for solving the problem]

[0007] As a result of intensive research aimed at solving the above problems, the inventors of the present application discovered that 2-oxazolidinones can be produced from propargylamines and carbon dioxide by using a silica catalyst, and completed the invention disclosed in the present application.

[0008] That is, a method for producing 2-oxazolidinones according to one embodiment of the present application includes a cyclization reaction step of reacting a propargylamine represented by the following general formula (I) with carbon dioxide in the presence of a catalyst containing silica as an active ingredient to produce a 2-oxazolidinone represented by the following general formula (II).

[0009] [ka]

[0010] [ka]

[0011] R 1 , R 2 , R 3 , and R 4 R each independently represents a hydrogen atom or a substituent having 1 to 20 carbon atoms which may contain at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom. 2 and R 3 may be bonded to form a ring.

[0012] A method for producing 2-oxazolidinones according to another embodiment of the present application includes a cyclization reaction step of reacting the propargylamines represented by the above general formula (I) with carbon dioxide in the presence of a catalyst containing silica, without containing a catalytic metal or a catalytic organic substance, to produce 2-oxazolidinones represented by the above general formula (II). 1 , R 2 , R 3 , and R 4 is the same as above. Effect of the Invention

[0013] The method for producing 2-oxazolidinones of the present invention uses a catalyst containing silica as an active ingredient, or a catalyst containing silica without containing catalytic metals or catalytic organic substances, which is inexpensive, available, and reusable, and therefore allows the production of 2-oxazolidinones. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The method for producing 2-oxazolidinones of the present application will be described below with specific examples. However, the method for producing 2-oxazolidinones of the present application is not limited to the following content and can be appropriately modified without departing from the spirit of the present application. In the present application, the symbol "to" indicating a numerical range includes the numerical values ​​before and after it as the lower and upper limits.

[0015] The present inventors have conducted extensive research in search of a new method for producing 2-oxazolidinones useful as intermediates for pharmaceuticals and agrochemicals, and as a result have discovered a cyclization reaction step in which 2-oxazolidinones are produced from propargylamines and carbon dioxide in the presence of a silica catalyst. Silica is available as a catalyst at low cost. In addition, carbon dioxide, which is non-toxic and inexpensive and is considered to be one of the causes of global warming, can be used. That is, the method for producing 2-oxazolidinone according to an embodiment of the present application includes a cyclization reaction step in which propargylamines represented by the following general formula (I) are reacted with carbon dioxide in the presence of a catalyst containing silica as an active ingredient to produce 2-oxazolidinones represented by the following general formula (II).

[0016] [ka]

[0017] [ka]

[0018] R 1 , R 2 , R 3 , and R 4 may each independently be a hydrogen atom, or a substituent having 1 to 20 carbon atoms which may contain at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom. The phrase "which may contain at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom" refers to an amino group (-NH2 This indicates that the carbon skeleton may contain at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom contained in, for example, a nitrogen atom, an oxygen atom, a sulfur atom, and a halogen atom contained in, for example, a hydroxy group (-OH), a mercapto group (-SH), or a fluoro group (-F), and that the carbon skeleton may contain a linking group containing a nitrogen atom, an oxygen atom, or a sulfur atom, such as an imino group (-NH-), an ether group (-O-), a carbonyl group (-C(=O)-), or a thioether group (-S-).

[0019] The substituent having 1 to 20 carbon atoms is a hydrocarbon group having 1 to 20 carbon atoms, or a hydrocarbon group in which at least a part of the carbon or hydrogen is substituted with the above-mentioned nitrogen atom or the like, and the substituent has 1 to 20 carbon atoms after the substitution. This hydrocarbon group is not limited to a linear saturated hydrocarbon group, and may contain one or more of a carbon-carbon unsaturated bond, a branched structure, and a cyclic structure. 2 and R 3 may be bonded to form a ring. The cyclization reaction step is represented by the following chemical reaction formula:

[0020] [ka]

[0021] It is believed that the cyclization reaction proceeds by activating the triple bond of the propargylamines with the silica in the catalyst. More specifically, as shown in the reaction mechanism below, it is believed that the cyclization reaction proceeds by activating the triple bond of the propargylamines through the hydroxyl group-π interaction on the silica surface. The catalyst may be composed of silica only. Note that a catalyst composed of silica and unavoidable impurities other than silica also falls under the category of a catalyst composed of silica only.

[0022] [ka]

[0023] The specific type of silica is not particularly limited and can be appropriately selected according to the purpose. Silica is roughly classified into crystalline silica having a crystal structure and amorphous silica having no crystal structure. The silica in the catalyst used in the method for producing 2-oxazolidinone of the present embodiment may be any type. Examples of crystalline silica include mesoporous silica such as MCM-41 or SBA-15. Examples of amorphous silica include silica gel such as CARiACT Q-6 or silica for chromatography. Among these, it is preferable that the silica is mesoporous silica. This is because 2-oxazolidinones can be obtained in high yield.

[0024] The particle size of silica is preferably 0.5 nm to 5 mm, more preferably 0.1 to 300 μm. Silica is insoluble in most organic solvents that can be reaction solvents. Therefore, silica can be recovered by filtering the reaction solution after the reaction is completed, and the catalyst can be reused (recycled). In the method for producing 2-oxazolidinone of this embodiment, a catalyst containing silica without containing catalytic metal and catalytic organic substance may be used. This is because the cyclization reaction proceeds sufficiently even if the catalyst containing silica does not contain catalytic metal and catalytic organic substance. In addition, the catalyst not containing catalytic metal and catalytic organic substance is available at low cost.

[0025] The catalyst may be provided with silica-coated magnetic nanoparticles, which are composed of magnetic nanoparticles and silica that coats the magnetic nanoparticles. After the reaction is completed, the catalyst can be collected by drawing it to a magnet, making it possible to recycle the catalyst. As the magnetic nanoparticles, maghemite (γ-Fe 2 O 3 ) and other magnetic iron compound nanoparticles. Magnetic nanoparticles include M(II)Fe 2 O 4 Ferrite nanoparticles having the following composition are preferred: magnetite Fe 3 O 4 More preferred are magnetic nanoparticles containing, for example, 50 wt% or more of M(II). 2+ , Co 2+ , Ni2+ , Mn 2+ , Zn 2+ , Mg 2+ , Cu 2+ and combinations thereof.

[0026] Silica-coated magnetic nanoparticles can be produced, for example, by the following method. First, magnetic nanoparticles are prepared in water. Next, tetraethoxysilane is added to this suspension and vigorously stirred to obtain silica-coated magnetic nanoparticles. Silica-coated magnetic nanoparticles are also commercially available as a water suspension, and can be used as is by replacing the water, which is the dispersion medium, with the reaction solvent.

[0027] The particle size of the primary particles of the magnetic nanoparticles is preferably 0.5 to 1000 nm, more preferably 5 to 100 nm. The primary particles of the magnetic nanoparticles are generally often aggregated. The silica in the silica-coated magnetic nanoparticles may coat one magnetic nanoparticle or a plurality of magnetic nanoparticles. The ratio of the mass of the magnetic nanoparticles to the mass of the silica (mass of magnetic nanoparticles / mass of silica) is not limited, but is usually 100 or less, preferably 10 or less, and usually 0.1 or more, preferably 1 or more. The catalyst may be composed only of silica-coated magnetic nanoparticles. A catalyst composed of silica-coated magnetic nanoparticles and unavoidable impurities other than silica-coated magnetic nanoparticles also falls under the category of a catalyst composed only of silica-coated magnetic nanoparticles.

[0028] The amount of catalyst used in the cyclization reaction step is usually 1 mg or more, preferably 10 mg or more, more preferably 50 mg or more, and usually 5 g or less, preferably 1 g or less, more preferably 200 mg or less, per 1 mmol of propargylamines. This is because 2-oxazolidinones can be obtained in high yield. The 2-oxazolidinones can be appropriately selected depending on the purpose of production. The raw material propargylamines are selected depending on the 2-oxazolidinones to be produced.

[0029] R 1 When R is a substituent other than a hydrogen atom,1 The number of carbon atoms in R is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, and is preferably 15 or less, and more preferably 10 or less. 2 and R 3 When R is a substituent other than a hydrogen atom, 2 and R 3 The number of carbon atoms in R is preferably 15 or less, more preferably 12 or less, and even more preferably 6 or less. 4 When R is a substituent other than a hydrogen atom, 4 The number of carbon atoms is preferably 15 or less, more preferably 12 or less, and further preferably 7 or less.

[0030] Also, R 1 , R 2 , R 3 , and R 4 The functional groups contained in 2 ), nitro group (-NO 2 ), cyano group (-CN), hydroxy group (-OH), mercapto group (-SH), fluoro group (-F), chloro group (-Cl), bromo group (-Br), carboxy group (-COOH), imino group (-NH-), ether group (-O-), carbonyl group (-C(=O)-), and thioether group (-S-).

[0031] R 1 , R 2 , R 3 , and R 4 Examples of the aryl group include a hydrogen atom, alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and a t-butyl group, aryl groups such as a phenyl group, a cyanophenyl group, a methoxyphenyl group, a methylphenyl group, a (trifluoromethyl)phenyl group, and a chlorophenyl group, and aralkyl groups such as a benzyl group and a diphenylmethyl group.

[0032] Among these, R 1is preferably a hydrogen atom, or an aryl group such as a phenyl group, a cyanophenyl group, a methoxyphenyl group, a methylphenyl group, a (trifluoromethyl)phenyl group, or a chlorophenyl group, and is particularly preferably a hydrogen atom, a phenyl group, a cyanophenyl group, or a (trifluoromethyl)phenyl group. 2 and R 3 is preferably a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, or a t-butyl group, or an aralkyl group such as a benzyl group, and is particularly preferably a hydrogen atom or a methyl group. 4 is preferably an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, or a t-butyl group, or an aralkyl group such as a benzyl group, with a methyl group and a benzyl group being particularly preferred.

[0033] The specific operation procedure and reaction conditions in the cyclization reaction step are not particularly limited and can be appropriately selected according to the purpose. Carbon dioxide is a gas at room temperature to reaction temperature and normal pressure, so it is usually charged in a gas phase into a reaction vessel and reacted with propargylamines in a gas-liquid phase. When the reaction is carried out in a batch reaction vessel, propargylamines, a catalyst, and a solvent are charged into the reaction vessel, the reaction vessel is heated to a predetermined reaction temperature, and then carbon dioxide gas is filled into the reaction vessel to set the pressure, and the reaction is carried out for a predetermined reaction time while stirring. The reaction temperature is usually 30°C or higher, preferably 70°C or higher, more preferably 100°C or higher, and even more preferably 120°C or higher, and usually 250°C or lower, preferably 180°C or lower, and more preferably 140°C or lower. This is because 2-oxazolidinones can be obtained in high yield.

[0034] Since carbon dioxide is consumed by the reaction, the pressure in the reaction vessel decreases as the reaction proceeds. Therefore, the pressure can be maintained by constantly supplying carbon dioxide to the reaction vessel, or sufficient carbon dioxide can be pre-filled in the reaction vessel. If the pressure in the reaction vessel at the start of the reaction is the reaction pressure, the lower limit of the reaction pressure depends on the reaction scale and the volume of the reaction vessel, but the reaction pressure is usually 0.001 MPa or more, preferably 0.1 MPa or more, more preferably 1 MPa or more, and usually 10 MPa or less, preferably 7 MPa or less, more preferably 5 MPa or less.

[0035] In addition, since the reaction pressure can be set high, it is preferable to use a pressure-resistant metal reaction vessel (autoclave) as the reaction vessel. In addition to carbon dioxide gas, an inert gas such as nitrogen gas or argon gas may coexist in the gas phase. When carbon dioxide gas and an inert gas coexist, the above reaction pressure range is replaced by the partial pressure range of carbon dioxide gas in the reaction vessel at the start of the reaction.

[0036] A solvent may or may not be used. When a solvent is used, the solvent is preferably a hydrocarbon solvent such as toluene, xylene, octane, nonane, and decane. The solvent may be an alcohol solvent such as 1-propanol, 2-propanol, butanol, or t-butanol, or an aprotic solvent such as acetonitrile, propionitrile, acetone, N,N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, or dioxane.

[0037] The reaction time is usually 0.5 hours or more, preferably 3 hours or more, more preferably 6 hours or more, and usually 72 hours or less, preferably 48 hours or less, more preferably 24 hours or less. After the reaction is completed, the catalyst can be recovered by filtering the reaction solution with a glass filter. The catalyst can be reused by adding the recovered catalyst and reaction substrates, etc. to the reaction vessel again. When using a catalyst having silica-coated magnetic nanoparticles, the catalyst can be recovered by drawing a magnet close to the reaction vessel after the reaction is completed, attracting the catalyst, and removing the reaction solution by decantation. Then, the catalyst can be reused by adding the reaction substrates, etc. to the reaction vessel again. In this way, the catalyst can be recycled with a simple operation.

[0038] After recovering the catalyst, the reaction solution 1 The H NMR measurement confirms that 2-oxazolidinones have been produced. After concentrating the reaction solution, the product can be isolated by separation and purification using column chromatography. The eluent for column chromatography can be, but is not limited to, ester solvents such as ethyl acetate, methyl acetate, ethyl propionate, and methyl propionate, hydrocarbon solvents such as hexane and toluene, alcohol solvents such as methanol and ethanol, halogenated solvents, and mixtures of these. EXAMPLES

[0039] The present invention will be described in more detail below with reference to examples and comparative examples. The present invention can be modified as appropriate without departing from the spirit of the present application. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

[0040] Examples 1 to 3 and Comparative Examples 1 to 4: Types of Catalysts Under an argon atmosphere, at room temperature, propargylamines (0.4 mmol) represented by the following chemical formula (III), toluene (1 mL), and various catalysts (80 mg) listed in Table 1 below were charged into an autoclave, which is a reaction vessel, and sealed. The vessel was then heated to 120°C, carbon dioxide gas was filled at 3 MPa, and the reaction liquid was stirred while reacting for 5 hours. In Example 1, silica Q-6 (Fuji Silysia Chemical, CALiACT Q-6), in Example 2, MCM-41 (Aldrich, 643645), and in Example 3, SBA-15 (Aldrich 777242) were dried at 110°C under vacuum and reduced pressure for 20 hours and used. Since no mass loss was observed under these drying conditions for basic alumina (Comparative Example 1) and acidic alumina (Comparative Example 2), and since hydrotalcite (Comparative Example 3) contains water molecules in its composition formula, commercially available reagents were used as they were. In Comparative Example 4, no catalyst was used.

[0041] [ka]

[0042] After the reaction was completed, the carbon dioxide gas was removed from the autoclave under ice cooling, and the pressure inside the autoclave was returned to normal. The catalyst was filtered off and washed with dichloromethane. 2-(benzyloxy)naphthalene was added as an internal standard to the mixture of the reaction solution and the catalyst washing solution, and dissolved therein. A portion of the mixture was then taken out and the solvent was distilled off under reduced pressure. 1 The structure of the 2-oxazolidinone represented by the above chemical formula (IV) was identified by H NMR, and the yield of the 2-oxazolidinone was calculated (hereinafter the same). The results are shown in Table 1. As shown in Table 1, when the mesoporous silica MCM-41 was used, the 2-oxazolidinone was obtained in the highest yield.

[0043] [Table 1]

[0044] Examples 4-5: Amount of catalyst Except for changing the mass of the catalyst to 20 mg or 40 mg, SiO 2 2-Oxazolidinones were synthesized in the same manner as in Example 2 using (MCM-41). The results are shown in Table 2. As shown in Table 2, when 40 mg of the catalyst was used, 2-oxazolidinones were obtained in the highest yield.

[0045] [Table 2]

[0046] Examples 6 to 11: Carbon dioxide pressure and reaction temperature 2-Oxazolidinones were synthesized in the same manner as in Example 5, except that the carbon dioxide pressure and reaction temperature were changed as shown in Table 3, and the reaction time was changed to 3 hours. The results are shown in Table 3. As shown in Table 3, when the carbon dioxide pressure was 5 MPa and the reaction temperature was 120 to 140°C, 2-oxazolidinones were obtained in high yield.

[0047] [Table 3]

[0048] Examples 12-17: Synthesis of various 2-oxazolidinones Various 2-oxazolidinones were synthesized under the reaction conditions shown in Table 4 by the same operation as in Example 9 (see the chemical reaction formula below). However, in Example 13, carbon dioxide gas was charged at 5 MPa at room temperature, and then the temperature was raised to the reaction temperature. The gauge pressure in the autoclave when the reaction temperature was reached was 5.98 MPa. The results are shown in Table 4. As shown in Table 4, various 2-oxazolidinones were obtained from various propargylamines.

[0049] [ka]

[0050] [Table 4]

[0051] In addition, the 2-oxazolidinones represented by the above chemical formula (IV) obtained in Example 12 were isolated and purified by the following procedure. After the reaction was completed, the carbon dioxide gas was removed from the autoclave under ice cooling, and the pressure inside the autoclave was returned to normal. The catalyst was filtered off and washed with dichloromethane. The mixture of the reaction solution and the catalyst washing liquid was distilled under reduced pressure, and the residue was purified by silica gel chromatography (eluent: hexane-ethyl acetate) (yield 84%).

[0052] 1 H NMR (400 MHz, CDCl 3 )δ / ppm 7.40-7.30(m,3H),7.29-7.26(m,2H),4.74(td,1H,J=3.0,2.7Hz),4.47(s,2H),4.24(td,1H,J=3.1,2.2Hz),4.02(dd,2H,J=2.4,2.4Hz).

[0053] Example 18: Reuse of catalyst Under an argon atmosphere, at room temperature, a propargylamine represented by the following chemical formula (V) (4 mmol), toluene (5 mL), and SiO 2 (MCM-41) (400 mg) was placed in an autoclave, which was then sealed and filled with carbon dioxide gas at 5 MPa. The autoclave was then heated to 110°C (gauge pressure inside the autoclave was 6.60 MPa), and the reaction liquid was stirred while reacting for 10 hours (see the chemical reaction formula below).

[0054] [ka]

[0055] After the reaction was completed, the carbon dioxide gas was removed from the autoclave under ice cooling, and the inside of the autoclave was brought to normal pressure. The catalyst was filtered under an argon atmosphere, and the catalyst was washed with dichloromethane and 2-propanol. After vacuum drying, the recovered catalyst was put into the autoclave and reused. Meanwhile, in the same manner as in Example 1, the structure of the 2-oxazolidinones contained in the mixed solution of the reaction solution and the catalyst washing solution and represented by the above chemical formula (VI) was identified, and the yield of the 2-oxazolidinones was calculated to be 68% (first use). This was repeated to calculate the yield of the 2-oxazolidinones from the second to tenth uses of the catalyst. As a result, the yield of the 2-oxazolidinones was 74% (second use) to 81% (fifth use, seventh use, and eighth use). That is, even when the catalyst was reused, the 2-oxazolidinones were obtained in high yield.

[0056] Examples 19 to 23, Comparative Examples 5 to 6, and Reference Example 1: Silica-coated magnetite catalyst Under argon atmosphere, silica SiO 2 Magnetite Fe per mass 3 O 4 The ratio of mass of (Fe 3 O 4 mass / SiO 2 The mass of silica-coated magnetite (SiO 2 / Fe 3 O 4 0.5 g of silica-coated magnetite was suspended in 25 mL of water, and 4 mL of a suspension (Cosmobio, TS-1010-1) was added to the autoclave. A magnet was brought close to the outer wall of the autoclave to attract the silica-coated magnetite to the inner wall of the autoclave, and the water in the autoclave was then removed by decantation. 2-propanol was added to the autoclave, which was then shaken well, followed by decantation, which was repeated three times. Furthermore, toluene was added to the autoclave, which was then shaken well, followed by decantation, which was repeated three times. Thus, silica-coated magnetite impregnated with toluene was obtained in the autoclave.

[0057] Under an argon atmosphere, at room temperature, the propargylamines (0.4 mmol) represented by the above chemical formula (III) and toluene (4 mL) were charged into the autoclave and sealed, and then carbon dioxide gas was charged at 1 to 3 MPa, heated to the reaction temperature shown in Table 5, and reacted for 20 hours while stirring the reaction liquid to synthesize 2-oxazolidinones represented by the above chemical formula (IV). After the reaction was completed, the carbon dioxide gas was released from the autoclave under ice cooling, and the pressure inside the autoclave was adjusted to normal pressure. By bringing a magnet close to the outer wall of the autoclave, the silica-coated magnetite was attracted to the inner wall of the autoclave, and the reaction solution was decanted and further washed with 2-propanol four times and with toluene three times (Examples 19 to 23).

[0058] On the other hand, no catalyst was used in Comparative Example 5. In Comparative Example 6 and Reference Example 1, raw materials propargylamines (0.4 mmol), toluene (4 mL), and catalyst (80 mg) were charged into an empty autoclave under an argon atmosphere at room temperature, and the reaction was then carried out in the same manner as in Examples 19 to 23. In Reference Example 1, a mixture of the reaction solution and the catalyst washing liquid was obtained in the same manner as in Example 1, and the yield was determined. The results are shown in Table 5. As shown in Table 5, it was found that the reaction was promoted by silica-coated magnetite having silica on its surface. In addition, when the carbon dioxide pressure was 2 to 3 MPa and the reaction temperature was 120°C, 2-oxazolidinones were obtained in high yield.

[0059] [Table 5]

[0060] Example 24: Reuse of silica-coated magnetite catalyst After the reaction of Example 19 was completed, carbon dioxide gas was removed from the autoclave under ice cooling, and the inside of the autoclave was brought to normal pressure. A magnet was brought close to the outer wall of the autoclave under an argon atmosphere, the silica-coated magnetite was attracted to the inner wall of the autoclave, and the reaction solution was decanted. Furthermore, the silica-coated magnetite catalyst was washed four times with 2-propanol and three times with toluene. The raw material propargylamines and toluene were put into this autoclave containing the silica-coated magnetite catalyst, and the reaction was carried out again in the same manner as in Example 19. This was repeated, and the yields of 2-oxazolidinones from the second to seventh uses of the catalyst were calculated. As a result, the yields of 2-oxazolidinones were 82% (sixth use) to 89% (second use, third use). That is, even if the catalyst was reused, 2-oxazolidinones were obtained in high yield.

[0061] Examples 25-29: Synthesis of various 2-oxazolidinones using silica-coated magnetite catalyst Various 2-oxazolidinones were synthesized under the reaction conditions shown in Table 6 by the same operation as in Example 19 (see the following chemical reaction formula). However, in Examples 27 to 29, the reaction vessel was sealed, heated to the reaction temperature, and then filled with carbon dioxide gas. The results are shown in Table 6. As shown in Table 6, various 2-oxazolidinones were obtained from various propargylamines.

[0062] [ka]

[0063] [Table 6]

Claims

1. The method includes a cyclization reaction step of reacting a propargylamine represented by the following general formula (I) with carbon dioxide in the presence of a catalyst containing silica, using 1 g or more of the silica per 1 mol of the propargylamine, at a reaction temperature of 110° C. or higher to produce a 2-oxazolidinone represented by the following general formula (II), The method for producing 2-oxazolidinones, wherein the silica is an active ingredient in a reaction in which the propargylamines are reacted with carbon dioxide to produce the 2-oxazolidinones. [Formula 1] [chemical 2] (R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a 4-CF 3 C 6 H 4 group, or a 4-CNC 6 H 4 group. ２ and R ３ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ４ represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a benzyl group.

2. In claim 1, A method for producing 2-oxazolidinones, comprising reacting the propargylamines with carbon dioxide at a reaction temperature of 120 to 140°C.

3. In claim 1 or 2, A method for producing 2-oxazolidinones, wherein the silica is mesoporous silica.

4. In any one of claims 1 to 3, The method for producing 2-oxazolidinones, wherein the catalyst is composed only of silica.

5. A method for producing a 2-oxazolidinone represented by the following general formula (II), comprising a cyclization reaction step of reacting a propargylamine represented by the following general formula (I) with carbon dioxide in the presence of a catalyst containing silica, using 1 g or more of the silica per 1 mol of the propargylamine, at a reaction temperature of 110°C or higher, The method for producing 2-oxazolidinones is characterized in that the catalyst does not contain a catalytic metal or a catalytic organic substance that promotes the reaction of reacting the propargylamines with carbon dioxide to produce the 2-oxazolidinones. [Formula 1] [chemical 2] (R １ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a 4-CF 3 C 6 H 4 group, or a 4-CNC 6 H 4 group. ２ and R ３ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ４ represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or a benzyl group.

6. In claim 1, 2, or 5, The catalyst comprises silica-coated magnetic nanoparticles composed of magnetic nanoparticles and silica coating the magnetic nanoparticles.

7. In claim 6, A method for producing 2-oxazolidinones, wherein the catalyst is composed only of the silica-coated magnetic nanoparticles.

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