Fluorine-containing isoxazolidine-5-ketone as well as synthesis method and anti-tumor application thereof

Abstract

The invention relates to fluorine-containing isoxazolidine-5-ketone as well as a synthesis method and anti-tumor application thereof. According to the synthesis method, gem-difluorocycloacrylimide and nitrone are taken as substrates, Ni (ClO4) 2.6 H2O is taken as a catalyst, (+ / -)-2, 2 '-(propane-2, 2-diyl) bis (4-phenyl-4, 5-dihydrooxazole) is taken as a ligand (L) in an organic solvent, cycloaddition isomerization reaction is carried out at about 30 DEG C, and the fluorine-containing isoxazolidine-5-ketone compound is obtained. And the fluorine-containing isoxazolidine-5-ketone is obtained through preparation. The method is mild in reaction condition, capable of being well compatible with various functional groups and high in yield, and the product further has certain biological activity and can inhibit proliferation of cancer cells. The invention discloses the realization of the cycloisomerization reaction of the gem-difluorocyclopropene and the nitrone for the first time, provides a new idea for the synthesis of the fluorine-containing isoxazolidine-5-ketone and the derivative thereof, and has a good application prospect in the fields of medicines and synthesis.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic compound synthesis process, and relates to a compound fluorine-containing isoxazolidin-5-ketone and a synthesis method thereof, and discloses antitumor biological activity of the compound. BACKGROUND

[0002] Fluorine atom occupies an important position in the fields of drug modification and organic synthesis due to its unique properties. In drug research, C The high bond energy of F bond can endow the compound with extremely high stability, and reduce the degradation of the compound by enzymes in the organism; when the hydrogen atom is replaced by the fluorine atom, the structure of the parent molecule hardly changes due to the similar van der Waals radius of the two, and the parent molecule can be smoothly recognized by the biological target and enter the specific position of the organism to participate in the metabolic process; the introduction of the fluorine atom can also increase the lipophilicity of the compound, thereby strengthening the absorption of the drug molecule by the organism.

[0003] It is difficult to find natural fluorine-containing organic matter in nature. Therefore, selectively introducing fluorine atoms or fluorine-containing structures into organic molecules is an important research topic in organic methodology. Difluoromethylene ( CF2 ) is one of the most common fluorine-containing building blocks for modifying molecular properties, and the introduction of the same into a cyclopropene structure can obtain novel and multifunctional gem-difluorocyclopropene compounds. The compounds have a unique structure and extremely high ring strain, and often exhibit extremely strong reactivity in chemical reactions, and can introduce fluorine atoms in the final product.

[0004] On the other hand, the isoxazolidin-5-one skeleton is developed from the isoxazole ring structure which has been applied to anticancer drugs for a long time, and has additional adjustable sp 3 carbon atoms and stereocenters, exists in many natural products and drug molecules ( Figure 1 ), and is also widely concerned by organic workers as an excellent synthetic intermediate in the field of catalytic synthesis. In view of its important application value, the synthesis strategy of the isoxazolidin-5-one skeleton has been widely concerned by synthetic workers in the past more than 20 years. The existing synthesis methods are generally divided into four categories, namely, aza-Michael addition reaction, cyclization reaction based on nitroso compound, cyclization reaction based on nitroketone, and functional modification of the existing isoxazolidin-5-one skeleton. The known advantage synthesis strategy is the aza-Michael addition strategy of hydroxylamine derivative, and there are few reports about other schemes, especially the cyclization strategy based on nitroketone. The existing reactions involving nitroketone can only use Meldrum acid raw materials or use phosphorus ylide to construct step by step (such as Figure 2(As shown), therefore, developing new dipole-loving substrates is of great significance for the derivatization and functionalization of such key heterocyclic frameworks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a fluorinated isoxazolidine-5-one in order to overcome the shortcomings of the prior art. The invention discloses for the first time the realization of the cycloaddition isomerization reaction of geminitrodifluorocycloacrylimide and nitrone, and constructs a novel heterocyclic compound fluorinated isoxazolidine-5-one skeleton in one step, providing a new approach for the synthesis of fluorinated isoxazolidine-5-one and its derivatives.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows: A fluorinated isoxazolidine-5-one, the general structural formula of which is shown in Formula 1, wherein R 1 Selected from aryl, R 2 Selected from aryl or alkyl groups, Bn represents benzyl.

[0007] Formula 1 Furthermore, R 1 It is phenyl; R 2 Selected from phenyl, alkylphenyl, alkoxyphenyl (such as 4-methoxyphenyl), fluoroalkylphenyl (such as 4-trifluoromethylphenyl), fluorophenyl (such as 4-fluorophenyl), naphthyl (such as 2-naphthyl), alkyl (such as ethyl, isopropyl), etc.

[0008] This invention provides a method for synthesizing a fluorinated isoxazolidine-5-one, which uses gem-difluorocycloacrylimide (structure shown in Formula 2) and N-benzylnitroketone (structure shown in Formula 3) as substrates. Under a protective atmosphere and in an organic solvent, with the aid of a metal catalyst and a racemic bisoxazoline ligand, a cycloaddition isomerization reaction occurs to obtain the fluorinated isoxazolidine-5-one compound. The general reaction formula is shown in Formula 4.

[0009] Formula 2 Formula 3 Formula 4 R in Equations 2, 3, and 4 1 and R 2 The meaning of the symbol is the same as in Equation 1.

[0010] According to the above scheme, the metal salt Lewis acid catalyst is selected from Ni(ClO4)2·6H2O, Fe(ClO4)3·H2O, Fe(OTf)3, Fe(OTf)2, Ni(OTf)2, etc., with Ni(ClO4)2·6H2O being the optimal metal salt catalyst; the racemic bisoxazoline ligand is preferably (±)-2,2'-(propane-2,2-diyl)bis(4-phenyl-4,5-dihydrooxazol) as ligand (L).

[0011] According to the above scheme, the organic solvent is selected from CH2Cl2, (CH2Cl)2, CHCl3, THF, toluene, etc., and is preferably dichloromethane (CH2Cl2); the amount of solvent used is preferably such that the concentration of gem-difluorocycloacrylimide therein is 0.1~0.3 mmol / mL, and more preferably 0.15~0.25 mmol / mL.

[0012] According to the above scheme, the protective atmosphere can be nitrogen or an inert atmosphere.

[0013] According to the above scheme, the reaction temperature is 15~60℃ and the reaction time is 24~36 h.

[0014] According to the above scheme, the molar ratio of geminitrocellulose and N-benzyl nitrone is 1:(1~1.5).

[0015] According to the above scheme, the molar ratio of the metal salt catalyst to geminitrocellulose is (0.05~0.15):1.

[0016] According to the above scheme, the molar ratio of racemic bisoxazoline ligand to gem-difluorocycloacrylamide is (0.06~0.18):1, preferably (0.1~0.15):1.

[0017] Based on the above, the present invention provides a more specific method for synthesizing fluorinated isoxazolidin-5-one, comprising the following steps: under a protective atmosphere, a metal catalyst and a racemic bisoxazoline ligand are mixed in an organic solvent and stirred to achieve coordination between the catalyst and the ligand. Then, geminal difluorocycloacrylimide and N-benzyl nitrone are added, and the reaction is stirred at 20-35°C until the geminal difluorocycloacrylimide is completely consumed (the consumption of geminal difluorocycloacrylimide can be detected by TLC). The resulting solution is then loaded onto a thin-layer chromatography silica gel plate and placed at 20-35°C for 4-12 h. Under the influence of water in the air (air humidity between 40% and 95%), the product conversion is completed. Then, a developing solvent is added for separation and purification to obtain the target product, fluorinated isoxazolidin-5-one.

[0018] According to the above scheme, the developing solvent is a mixture of petroleum ether and ethyl acetate. Specifically, the volume ratio of petroleum ether to ethyl acetate is (4~6):1.

[0019] According to the above scheme, the reaction can also be supplemented with 4Å molecular sieve and / or sodium carbonate as additives. Specifically, the 4Å molecular sieve is added together with the metal catalyst and the racemic bisoxazoline ligand, and the amount of 4Å molecular sieve added in the solvent is (25~75) mg / mL; sodium carbonate is added together with gem-difluorocycloacrylimide and N-benzyl nitrone, and the molar ratio of sodium carbonate to gem-difluorocycloacrylimide is (0.8~1.2):1, with 1:1 being optimal.

[0020] The fluoroisoxazolidine-5-one described in this invention can be used to prepare a drug that inhibits the proliferation of breast cancer cells.

[0021] This invention provides a fluorinated isoxazolidine-5-one and its synthesis method, such as... Figure 3 As shown, with gem-difluorocycloacrylamide and N Using benzyl nitrone as a starting material, a 1,3-dipolar cycloaddition reaction of geminal difluorocycloacrylimide and nitrone is achieved via Ni(ClO4)2·6H2O catalysis. The coordination of the two carbonyl oxygen groups of the nickel metal salt Ni(ClO4)2·6H2O and the geminal difluorocycloacrylimide causes a change from carbonyl to enol form, leading to the formation of an active intermediate (Formula I), which then undergoes a [3+2] cycloaddition reaction with nitrone. The resulting addition product (Formula II) cleaves N... After the O bond, it will be due to the difluoromethylene ( CF2 The presence of the ) structure leads to the fluoride elimination reaction with water, resulting in a stable conjugated structure (Formula III), followed by ring isomerization to remove the oxazolidinone, yielding the final product, fluorinated isoxazolidin-5-one (Formula IV).

[0022] Compared with the prior art, the beneficial effects of the present invention are: First, the present invention provides a novel compound containing fluoroisoxazolidine-5-one, which can be used as a drug for preparing drugs that inhibit the proliferation of breast cancer cells.

[0023] Secondly, this invention discloses for the first time the realization of the cycloaddition isomerization reaction of geminal difluorocycloacrylimide and nitrone, constructing a novel heterocyclic compound fluorinated isoxazolidin-5-one skeleton in one step, providing a new approach for the synthesis of fluorinated isoxazolidin-5-one and its derivatives. Specifically, the three-membered ring structure exhibits high ring strain for ring expansion reactions, allowing the olefin to act as an excellent dipolarophile in the cycloaddition reaction with the nitrone. The introduction of the difluoromethylene group can utilize the driving force of the intermediate fluorine elimination reaction to suppress other reaction pathways and obtain the fluorinated cycloisomerized product in high yield. The introduction of the carbonyl group and the dominant prosthetic group oxazolidinone can enhance the electrophilicity of the cyclopropene, provide bidentate chelating sites for coordination with Lewis acid catalysts, further activate the substrate, and provide the possibility for subsequent introduction of chiral Lewis acids to attempt enantioselective control.

[0024] Third, the cycloisomerization reaction of gem-difluorocyclopropene with nitroketone in this invention has the advantages of mild reaction conditions, simple operation, wide range of applicable substrates, and broad substrate applicability. It is compatible with a variety of functional groups and has a high yield of up to 82%. Furthermore, the product has anti-tumor activity and can inhibit the proliferation of breast cancer cells. Attached Figure Description

[0025] Figure 1 This is a typical example of an existing isoxazolidin-5-one skeleton.

[0026] Figure 2 The domino reaction of nitrone with an organic base catalyzes the synthesis of racemic isoxazolidin-5-one.

[0027] Figure 3 This describes the synthetic mechanism of the fluorinated isoxazolidine-5-one described in this invention. Detailed Implementation

[0028] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the present invention is not limited to the following embodiments.

[0029] The synthesis reaction equation for geminidinium difluorocycloacrylamide used in the following examples is shown in Formula 5. The specific synthesis process is as follows: The first step was the synthesis of acetylide imide: a magnetic flask and substituted propynic acid (10.0 mmol, 1.0 equiv) were added to a 100 mL dry two-necked flask (the first flask). After replacing the atmosphere with nitrogen, anhydrous tetrahydrofuran (20 mL) was added. The mixture was stirred at -78 °C and pentanoyl chloride (Me3CCOCl, 10.5 mmol, 1.05 equiv) and triethylamine (Et3N, 10.5 mmol, 1.05 equiv) were added dropwise sequentially using a syringe. After stirring for 15 min, the temperature was raised to 0 °C and the reaction was continued for 45 min.

[0030] Meanwhile, a magnetic stir bar and 2-oxazolidon (10.0 mmol, 1.0 equiv) were added to a 150 mL dry two-necked flask (the second flask). After purging with a nitrogen atmosphere, anhydrous tetrahydrofuran (20 mL) was added. The mixture was stirred at -78 °C, and a tetrahydrofuran solution of n-butyllithium was slowly added dropwise using a syringe. n -BuLi 2.5 mol / L inTHF (10.5 mmol, 1.05 equiv), and the reaction was maintained at this temperature for 15 min. Then, all the solution in the first flask was transferred to the second flask using a syringe, and the temperature was slowly raised to room temperature. The reaction was continued for 4 h. After the reaction was completed by TLC monitoring, 15 mL of saturated ammonium chloride solution was added to quench the reaction. The mixture was then extracted three times with 30 mL of ethyl acetate and washed three times with 15 mL of saturated sodium chloride solution. The mixture was then dried over anhydrous magnesium sulfate, filtered, concentrated, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 3:1) to obtain the corresponding acetylide imide product.

[0031] The second step was the synthesis of geminal difluorocycloacrylamide: A magnetic osmotic pressure, NaF (0.5 mmol, 10 mol%), acetylide imide (5.0 mmol, 1.0 equiv), and diethylene glycol dimethyl ether (diglyme, 1.5 mL) were added sequentially to a 5 mL reaction tube. After sealing with a rubber stopper and inserting a balloon, the reaction tube was placed in a 120°C oil bath and stirred. Trimethylsilyl 2-(fluorosulfonyl)difluoroacetate (TFDA, 5.0 mmol, 5.0 equiv) was added at a uniform rate over 5 h using a precision syringe pump. After the addition was complete, stirring was continued for 1 h. After the reaction was completed and cooled to room temperature, the product was directly purified by silica gel column chromatography (petroleum ether / dichloromethane = 1:3) to obtain the corresponding geminal difluorocycloacrylamide product. The specific structures of the substituted propynic acid, the corresponding acetylide imide, and the corresponding geminal difluorocycloacrylamide are shown in reaction equation 5.

[0032] Formula 5 The synthetic reaction equation for N-benzyl nitroketone used in the following examples is shown in Formula 6. The specific synthetic process is as follows: In a 100 mL round-bottom flask, a magnetic stir bar, a substituted aldehyde or ketone (11 mmol, 1.1 equiv), benzyl hydroxylamine hydrochloride (10.0 mmol, 1.0 equiv), sodium bicarbonate solid (20.0 mmol, 2.0 equiv), and anhydrous magnesium sulfate solid (30.0 mmol, 3.0 equiv) were added sequentially. Dichloromethane solvent (20 mL) was then added and the mixture was stirred at room temperature. After the reaction was monitored by TLC, the mixture was filtered through diatomaceous earth and washed with dichloromethane. The filtrate was concentrated and recrystallized from dichloromethane / petroleum ether or purified by silica gel column chromatography (petroleum ether / ethyl acetate = 1:1) to obtain the corresponding... N -Bn nitrone. Wherein, substituted aldehydes or ketones, benzyl hydroxylamine hydrochloride, and corresponding... N The specific structures of -Bn nitroketone are shown in reaction equation 6.

[0033] Formula 6 Example 1 A fluoroisoxazoline-5-one is synthesized by the following steps: In a glove box, a magnetic stir bar, catalyst Ni(ClO4)2·6H2O (0.01 mmol, 10 mol%), ligand (L) 2,2'-(propane-2,2-diyl)bis(4-phenyl-4,5-dihydrooxazole) (0.012 mmol, 12 mol%), 4Å molecular sieve (25 mg), and anhydrous dichloromethane solvent (0.5 mL) were added to a dry small test tube. The mixture was stirred at room temperature (around 30 °C) for 2 h to achieve pre-coordination of the catalyst and ligand. Subsequently, gem-difluorocycloacrylamide (0.1 mmol, 1.0 equiv), N-benzyl nitrone (0.12 mmol, 1.2 equiv), and sodium carbonate (0.1 mmol, 1.0 equiv) were added. The mixture was then sealed and removed from the glove box. The mixture was stirred at 30 °C, and the consumption of gem-difluorocycloacrylamide was monitored using TLC (the reactants typically react completely within 24 h). After the geminitrodifluorocycloacrylimide was consumed, the resulting solution was loaded onto a thin-layer chromatography silica gel plate and incubated at room temperature for 4 h. Then, a developing solvent (petroleum ether / ethyl acetate = 5:1, v / v) was added for separation and purification to obtain the target product, fluoroisoxazolidine-5-one (Formula 7), with a yield of 82%. The specific structures of the reactants geminitrodifluorocycloacrylimide, N-benzylnitroketone, and the product fluoroisoxazolidine-5-one are shown in Formula 8.

[0034] Formula 7 Formula 8 In Equation 8, R 1= Phenyl, R 2 = Phenyl.

[0035] The fluorinated isoxazolidine-5-one prepared in Example 1 is a white solid with a melting point of 69.4–71.6 °C and a half-maximal inhibitory concentration (IC50). 50 = 139.4, and combined with NMR and mass spectrometry, the product structure was confirmed to be consistent with the fluorinated isoxazolidin-5-one in Formula 7. Specifically, the NMR and mass spectrometry data are as follows: 1 H NMR (500 MHz, CDCl3) δ 7.85 (d, J = 7.5 Hz, 2H), 7.67–7.65 (m, 1H), 7.51–7.48 (m, 2H), 7.40–7.34 (m, 5H), 7.31–7.26 (m, 5H), 5.66 (s, 1H), 4.36(d, J = 13.5 Hz, 1H), 4.28 (d, J = 13.5 Hz, 1H) ppm; 13 C NMR (500 MHz, CDCl3) δ 186.1 (d, J = 31.9 Hz), 166.7, 156.2 (d, J = 303.9 Hz), 137.2, 134.7, 134.1 (d, J = 4.3 Hz), 133.7, 129.9, 129.7, 129.6, 128.80, 128.78, 128.7, 128.6, 128.5,127.6, 128.1 (d, J = 3.0 Hz), 67.9, 63.6 ppm; 19 F NMR (471 MHz, CDCl3) δ –99.5(s, 1F) ppm; HRMS (ESI) m / z: [M+H] + calcd for C 24 H 19 O3NF 388.1344; found:388.1347. Comparative Examples 1-7 To compare the effect of metal catalysts on the yield of the fluorinated isoxazolidine-5-one product, Comparative Examples 1-7 used essentially the same preparation process as Example 1, the only difference being the use of different metal salt catalysts. The metal salt catalysts used in Comparative Examples 1-7 and the yield of the fluorinated isoxazolidine-5-one product are shown in Table 1 below.

[0036] Table 1

[0037] As shown in Table 1, Ni(ClO4)2·6H2O in Example 1 and the metal salts in Comparative Examples 1, 2, 3, and 7 can all catalyze the reaction. Other metal salts produce less product or even fail to react. In Example 1, Ni(ClO4)2·6H2O exhibits excellent catalytic performance, achieving a yield of 82%, significantly higher than Comparative Examples 1-7. Therefore, the metal salt catalysts selectable in this invention include Ni(ClO4)2·6H2O, Fe(OTf)3, Fe(OTf)2, and Ni(OTf)2, with Ni(ClO4)2·6H2O being the most preferred.

[0038] Comparative Examples 8-13 To compare the effect of solvent on the yield of the fluoroisoxazolidine-5-one product, Comparative Examples 8-13 adopted essentially the same preparation process as Example 1, the only difference being the use of different organic solvents. The specific solvents used in Comparative Examples 8-13 and the yield of the fluoroisoxazolidine-5-one product are shown in Table 2 below.

[0039] Table 2

[0040] As shown in Table 2, the type of solvent directly affects the final yield. Compared to the dichloromethane solvent used in Example 1, other solvents can lead to problems such as incomplete conversion of the raw materials or numerous side reactions. Therefore, the solvents that can be selected in this invention include CH2Cl2, (CH2Cl)2, CHCl3, THF, and toluene. The yield decreases sequentially, but the effect of the solvent is slightly smaller than that of the metal salt catalyst, and the yield can reach over 35%. (CH2Cl)2 and CH2Cl2 are relatively more effective.

[0041] Comparative Examples 14-18 To investigate the effects of temperature and additives on the yield of the product fluoroisoxazolidine-5-one, Comparative Examples 14 and 15 differed from Example 1 in that the reaction temperature of 30°C in Example 1 was replaced with 0°C and 15°C, respectively.

[0042] The only difference between Comparative Example 16 and Example 1 is that 4 Å MS is not added.

[0043] Examples 17 and 18 differ from Example 1 only in that 4 Å MS is replaced with 25 mg of 800-mesh silica powder and 25 mg of water, respectively.

[0044] The additives, temperatures, and product yields used in Comparative Examples 14-18 are shown in Table 3.

[0045] Table 3

[0046] As shown in Table 3, the reaction yield was higher when the additive was 4 Å MS; the reaction yield was lower when no additive was used or other additives were used. Temperature also affects the reaction product yield; the yield decreased as the temperature decreased.

[0047] Example 2 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 9: Formula 9 The specific steps of its synthesis method are the same as in Example 1, except that: R 2 The product is 4-methoxyphenyl, and the yield is 43%. The product's properties, melting point, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: White solid, melting point: 42.8~43.9℃, half-maximal inhibitory concentration (IC50) 50 = 536.7; 1 H NMR (500 MHz, CDCl3) δ 7.73 (d, J = 7.5 Hz, 2H), 7.57 7.54 (m, 1H), 7.41 7.38 (m, 2H), 7.28 7.23 (m, 5H), 7.11 (d, J = 9.0 Hz, 2H), 6.69 (d, J = 9.0 Hz, 2H), 5.46 (s,1H), 4.21 (d, J = 14.0 Hz, 1H), 4.15 (d, J = 14.0 Hz, 1H), 3.66 (s, 3H) ppm; 13 CNMR (126 MHz, CDCl3) δ 186.1 (d, J = 31.8 Hz), 166.6 (d, J = 3.7 Hz), 156.0 (d,J = 301.6 Hz), 134.7, 134.1 (d, J = 4.5 Hz), 133.8, 132.0, 129.8, 129.7,129.64, 129.0, 128.7, 128.4, 118.4 (d, J = 3.8 Hz), 114.1, 67.6, 63.3, 55.3ppm; 19 F NMR (471 MHz, CDCl3) δ 99.6 (s, 1F) ppm; HRMS (ESI) m / z: [M+H] + calcdfor C 25 H 21 O4NF 418.1449; found: 418.1448, confirming that the product has the same structure as Formula 9.

[0048] Example 3 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 10: Formula 10 The specific steps of its synthesis method are the same as in Example 1, the difference being R 2 The product is 4-trifluoromethylphenyl, with a yield of 40%. The product's properties, melting point, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: White solid, melting point: 91.3~92.3℃, half-maximal inhibitory concentration (IC50) 50 =436.9; 1 H NMR (500 MHz, CDCl3) δ 7.87 (d, J = 8.0 Hz, 2H), 7.70 7.67 (m, 1H), 7.56 7.50 (m, 4H), 7.44 (d, J = 8.0 Hz, 2H), 7.39 7.35 (m, 5H), 5.72 (s, 1H), 4.42 (d, J = 13.5 Hz, 1H), 4.28 (d, J = 13.5 Hz, 1H) ppm; 13 C NMR (126 MHz, CDCl3) δ 186.1 (d, J= 31.9Hz), 166.5, 156.4 (d, J = 305.3 Hz), 141.2, 135.0, 133.9 (d, J = 4.7 Hz),133.2, 130.9, 130.6, 130.0, 129.8, 129.7, 129.0, 128.9, 128.8, 127.9, 125.7(q, J = 3.7 Hz), 123.8 (q, J = 272.5 Hz) 117.4 (d, J = 7.1 Hz), 67.0, 63.9 ppm; 19 F NMR (471 MHz, CDCl3) δ 62.82 (s, 3F), 98.71 (s, 1F) ppm; HRMS (ESI) m / z:[M+H] + calcd for C 25 H 18 O3NF4456.1217; found: 456.1220, confirming that the product has the same structure as Formula 8.

[0049] Example 4 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 11: Formula 11 The specific steps of its synthesis method are the same as in Example 1, except that: R 2 The product is ethyl, with a yield of 66%. The properties, melting point, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: White solid, melting point: 77.0~77.8℃, half-maximal inhibitory concentration (IC50) 50 =68.7; 1 H NMR (500 MHz, CDCl3) δ 7.91 (d, J = 7.5 Hz, 2H), 7.69–7.65 (m, 1H), 7.54–7.51 (m, 2H), 7.34–7.30(m, 5H), 4.45 (dd, J = 9.0 Hz, 4.0 Hz, 1H), 4.24 (d, J = 13.0 Hz, 1H), 4.09 (d, J= 13.0 Hz, 1H), 1.83–1.74 (m, 1H), 1.69–1.62 (m, 1H), 0.96 (t, J = 7.0 Hz, 3H) ppm; 13 C NMR (126 MHz, CDCl3) δ 177.7 (d, J = 32.9 Hz), 168.0 (d, J = 2.5 Hz), 154.9 (d, J = 302.7 Hz), 134.6, 134.5 (d, J = 4.8 Hz), 133.6, 130.1, 129.73,129.67, 128.8, 128.7, 128.4, 119.2 (d, J = 5.0 Hz), 66.2, 64.7, 27.9, 10.4ppm; 19 F NMR (471 MHz, CDCl3) δ –101.7 (s, 1F) ppm; HRMS (ESI) m / z: [M+H] + calcdfor C 20 H 19 O3NF 340.1344; found: 340.1347, confirming that the product has the same structure as Formula 11.

[0050] Example 5 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 12: Formula 12 The specific steps of its synthesis method are the same as in Example 1, except that: R 2 The product is isopropyl, with a yield of 80%. The properties, melting point, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: Pale yellow solid, melting point: 63.4~64.5℃, IC50 (half-maximal inhibitory concentration) 50 =68.8. 1 H NMR (500 MHz, CDCl3) δ 7.94 (d, J = 8.5 Hz, 2H), 7.71 7.68 (m, 1H), 7.57 7.53 (m, 2H), 7.38 7.32 (m, 5H), 4.49 (d, J = 5.0 Hz, 1H), 4.26 (d, J = 13.0 Hz, 1H), 4.12 (d, J =13.0 Hz, 1H), 2.04 1.95 (m, 1H), 0.95 (d, J = 6.5 Hz, 3H), 0.89 (d, J = 6.5 Hz, 3H) ppm; 13 C NMR (126 MHz, CDCl3) δ 186.9 (d, J = 32.7 Hz), 168.1 (d, J = 2.3Hz), 155.2 (d, J = 302.5 Hz), 134.6, 134.5 (d, J = 5.0 Hz), 133.6, 130.3,129.7, 129.67, 128.8, 128.7, 128.4, 118.3 (d, J = 5.0 Hz), 69.0, 65.0, 33.6,33.5, 19.4, 17.4 ppm; 19 F NMR (471 MHz, CDCl3) δ –99.5 (s, 1F) ppm; HRMS (ESI)m / z: [M+H] + calcd for C 21 H 21 O3NF 354.1500; found: 354.1501, confirming that the product has the same structure as Formula 12.

[0051] Example 6 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 13: Formula 13 The specific steps of its synthesis method are the same as in Example 1, except that: R 2 The product is a 4-fluorophenyl compound, with a yield of 45%. The product's properties, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: White solid, melting point: 106.4~107.7℃, IC50 concentration. 50 =330.7. 1 H NMR (500 MHz, CDCl3)δ 7.86 (d, J = 8.0 Hz, 2H), 7.69–7.66 (m, 1H), 7.53–7.49 (m, 2H), 7.39–7.34 (m, 5H), 7.31–7.29 (m, 2H), 6.99–6.95 (m, 2H), 5.62 (s, 1H), 4.36 (d, J =13.5 Hz, 1H), 4.26 (d, J = 13.5 Hz, 1H) ppm; 13 C NMR (126 MHz, CDCl3) δ 186.1 (d, J = 31.8 Hz), 166.5 (d, J = 1.9 Hz), 162.7 (d, J = 248.9 Hz), 156.2 (d, J =303.9 Hz), 134.8, 134.0 (d, J = 5.0 Hz), 133.5, 133.1, 129.9, 129.7, 129.65,129.5, 129.4, 128.8, 128.6, 118.0 (d, J = 3.5 Hz), 115.6 (d, J = 21.9 Hz), 67.1, 63.6 ppm; 19 F NMR (471 MHz, CDCl3) δ –99.24 (s, 1F), –113.06 (s, 1F) ppm; HRMS (ESI) m / z: [M+H] + calcd for C 24 H 18 O3NF2406.1249; found: 406.1250, confirming that the product has the same structure as Formula 13.

[0052] Example 7 A fluorinated isoxazolidine-5-one, the structure of which is shown in Formula 14: Formula 14 The specific steps of its synthesis method are the same as in Example 1, except that: R 2 The product is 2-naphthyl, with a yield of 48%. The product's properties, melting point, half-maximal inhibitory concentration (IC50), NMR data, and mass spectrometry data are as follows: Yellow solid, melting point: 52.9~53.7℃, IC50 concentration. 50 =59.0. 1 H NMR (500 MHz, CDCl3) δ 7.82 7.76 (m, 5H), 7.73 (s, 1H), 7.63 7.60 (m, 1H), 7.48 7.36 (m, 10H),5.81 (s, 1H), 4.41 (d, J = Hz, 1H), 4.32 (d, J = 13.5 Hz, 1H) ppm; 13 C NMR (126MHz, CDCl3) δ 186.1 (d, J = 31.4 Hz), 166.7, 156.3 (d, J = 303.9 Hz), 134.7,134.5, 134.1 (d, J = 4.0 Hz), 133.7, 133.2, 133.0, 129.9, 129.7, 129.6, 128.8,128.79, 128.7, 128.5, 128.2, 127.6, 127.0, 126.5, 126.4, 125.1, 118.0 (d, J =4.9 Hz), 68.0, 63.7 ppm; 19 F NMR (471 MHz, CDCl3) δ 99.02 (s, 1F) ppm; HRMS(ESI) m / z: [M+H] + calcd for C 28 H 21 O3NF 438.1500; found:438.1500, confirming that the product has the same structure as Formula 14.

[0053] Application examples The application of fluoroisoxazolidine-5-one in the preparation of drugs to inhibit the proliferation of breast cancer cells was investigated. The inhibitory effect of the compounds prepared in Examples 1-7 on the proliferation of mouse breast cancer 4T1 cells was studied using the CCK-8 assay. The main component of the CCK-8 reagent is WST-8. Succinate dehydrogenase (or other dehydrogenases) in the mitochondria of living cells can reduce WST-8 to an orange-yellow, water-soluble formazan dye. The amount of formazan generated is directly proportional to the number of living cells; the corresponding content of living cells can be obtained by measuring its absorbance value. The specific experimental steps are as follows: (1) Grouping and compound concentration configuration The experimental groups were set up as follows: a blank group (containing only complete culture medium), a control group (containing complete culture medium and mouse breast cancer 4T1 cells), and eight compound concentration gradient experimental groups (containing complete culture medium and mouse breast cancer 4T1 cells at concentrations of 150 μM, 120 μM, 100 μM, 80 μM, 60 μM, 50 μM, 20 μM, and 10 μM compounds, with 6 replicates per group. Concentration preparation for the experimental groups: the compound was dissolved in 0.5 mL of cell-grade DMSO solution and then diluted to the corresponding concentration with RMPI1640 complete culture medium.

[0054] (2) Cell plating and drug administration Centrifuged and digested 4T1 cells were diluted with complete culture medium to a concentration of 5.5 × 10⁴ cells / mL. The control and experimental groups were seeded at 5.5 × 10³ cells / well, 100 μL per well, in 96-well plates. The blank group received the same volume of complete culture medium. 100 μL of sterile PBS solution was added to the outermost ring of each well to prevent solvent evaporation. After seeding, the 96-well plates were placed in a cell culture incubator. After 24 hours, the old culture medium was aspirated. The blank and control groups were added with 100 μL of complete culture medium, while the experimental groups were added with 100 μL of complete culture medium for each concentration of the compound. The plates were then incubated for another 24 hours.

[0055] (3) Cell proliferation inhibition assay The old culture medium in the 96-well plate was aspirated, washed twice with sterile PBS solution, the PBS solution was aspirated, and the plate was incubated with 100 μL of 10% (v / v) CCK-8 complete culture medium in the dark for 30 minutes. The OD value at 450 nm was measured using a microplate reader, and the cell proliferation inhibition rate was calculated using formula (1). At the same time, the IC50 of the compound on breast cancer 4T1 cells was calculated using Graphpad Prism statistical software. 50 value.

[0056]

[0057] The fluorinated isoxazolidine-5-ones prepared in Examples 1-7 above showed an IC50 inhibitory concentration (IC50) of 1 / 3 at cell proliferation inhibition experiments. 50 Within the range of 59 to 536.7, it was confirmed to have anti-tumor activity and to inhibit the proliferation of breast cancer cells.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A fluoroisoxazolidine-5-one, characterized in that, The general structural formula is shown in Formula 1: Formula 1 Where R 1 Selected from aryl, R 2 Selected from aryl or alkyl groups, Bn represents benzyl.

2. The fluorinated isoxazolidine-5-one according to claim 1, characterized in that, R 1 It is phenyl; R 2 It is selected from one or more of phenyl, 4-methoxyphenyl, 4-trifluoromethylphenyl, 4-fluorophenyl, 2-naphthyl, ethyl, and isopropyl.

3. A method for synthesizing a fluorinated isoxazolidine-5-one according to claim 1 or 2, characterized in that, Using gem-difluorocycloacrylimide and N-benzyl nitrone as substrates, a cycloaddition isomerization reaction occurs under a protective atmosphere and with an organic solvent, a metal catalyst, and a racemic bisoxazoline ligand to yield the fluorinated isoxazolidine-5-one; wherein the structural formulas of gem-difluorocycloacrylimide and N-benzyl nitrone are shown in Formula 2 and Formula 3, respectively: Formula 2 Formula 3 R in Equations 2 and 3 1 and R 2 The meaning of the symbol is the same as in Equation 1.

4. The method for synthesizing fluorinated isoxazolidine-5-one according to claim 3, characterized in that, The metal salt Lewis acid catalyst is selected from one or more of Ni(ClO4)2·6H2O, Fe(ClO4)3·H2O, Fe(OTf)3, Fe(OTf)2, and Ni(OTf)2 in any proportion; the racemic bisoxazoline ligand is (±)-2,2'-(propane-2,2-diyl)bis(4-phenyl-4,5-dihydrooxazol).

5. The method for synthesizing fluorinated isoxazolidine-5-one according to claim 3, characterized in that, The organic solvent includes one or more of CH2Cl2, (CH2Cl)2, CHCl3, THF, and toluene in any proportion; the solvent amount is such that the concentration of geminidiafluorocycloacrylimide therein is 0.1~0.3 mmol / mL; the protective atmosphere is nitrogen or an inert atmosphere; the reaction temperature is 15~60℃, and the reaction time is 24~36 h.

6. The method for synthesizing fluorinated isoxazolidine-5-one according to claim 3, characterized in that, The molar ratio of geminitrocellulose to N-benzyl nitrone is 1:(1~1.5).

7. The method for synthesizing fluorinated isoxazolidine-5-one according to claim 3, characterized in that, The molar ratio of the metal salt catalyst to gem-difluorocycloacrylamide is (0.05~0.15):1; the molar ratio of the racemic bisoxazoline ligand to gem-difluorocycloacrylamide is (0.06~0.18):

1.

8. The method for synthesizing fluoroisoxazolidine-5-one according to any one of claims 3 to 7, characterized in that, The process includes the following steps: Under a protective atmosphere, a metal catalyst and a racemic bisoxazoline ligand are mixed in an organic solvent and stirred to achieve coordination between the catalyst and the ligand. Then, geminitrocellulose and N-benzylnitroketone are added, and the mixture is stirred at 20-35°C until the geminitrocellulose is consumed. The resulting solution is then loaded onto a thin-layer chromatography silica gel plate and placed at 20-35°C for 4-12 hours. The product conversion is completed under the action of water in the air. Finally, a developing solvent is added for separation and purification to obtain the target product, fluoroisoxazolidin-5-one.

9. The method for synthesizing fluorinated isoxazolidine-5-one according to claim 8, characterized in that, The developing solvent is a mixture of petroleum ether and ethyl acetate; 4Å molecular sieve and / or sodium carbonate are added as additives during the reaction; wherein, the 4Å molecular sieve is added together with the metal catalyst and the racemic bisoxazoline ligand, and the amount of 4Å molecular sieve added in the solvent is (25~75) mg / mL; sodium carbonate is added together with gem-difluorocycloacrylimide and N-benzyl nitrone, and the molar ratio of sodium carbonate to gem-difluorocycloacrylimide is (0.8~1.2):

1.

10. The use of the fluoroisoxazolidine-5-one according to claim 1 or 2 in the preparation of an antitumor drug.

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