A method for generating α-acyloxy ester compounds from oxosulfonium ylides and carboxylic acid compounds

Abstract

The present invention relates to a method for generating α-acyloxy esters from oxosulfonium ylides and carboxylic acid compounds. Using tris(pentafluorophenyl)borane as a catalyst, oxosulfonium ylides and carboxylic acids as raw materials, α-acyloxy esters are synthesized through O-H insertion. Compared with other methods, this method has simple steps, is mild and green, has atom economy and step economy, and is an effective method for preparing important α-acyloxy esters in organic compounds, with important application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic compound synthesis and application, and relates to a green synthesis method for constructing α-acyloxy esters by an O-H bond insertion reaction of an oxygen-sulfur ylide with carboxylic acids such as phenylacetic acid and benzoic acid catalyzed by tris(pentafluorophenyl)borane, while constructing a C-O bond. Background Art

[0002] α-Acyloxy esters are an important class of diester compounds with various biological uses. α-Acyloxy esters are the active moieties of many drugs, such as flurbiprofen axetil with analgesic effects [1] , cefuroxime axetil with antibacterial effects [2] , Cryptophycin with anticancer activity [3] , etc. Their synthesis was first carried out by Wolfrom et al. [4] introducing diazo compounds into carboxylic acids to synthesize α-acyloxy ester compounds through carbene insertion reactions. Industrially, diazo compounds are often avoided due to their exothermic decomposition, instability, potential toxicity to the environment, and potential explosive behavior. Using an oxygen-sulfur ylide as a carbene precursor to replace diazo compounds solves these problems to a certain extent. The oxygen-sulfur ylide is a stable crystalline solid, generating DMSO in the reaction instead of nitrogen like diazo compounds, so it will not cause a sharp increase in the pressure of the reaction system. At the same time, the more continuous and stable reaction characteristics of the oxygen-sulfur ylide can also make the reaction safer and more controllable, and the oxygen-sulfur ylide is more nucleophilic towards carbon than the corresponding diazo compounds [5] . After these characteristics of the oxygen-sulfur ylide were discovered, its preliminary applications in N-H bond [6] , B-H bond [7] , O-H bond [8] , P-H bond [9] insertion reactions have been successfully developed. There is an article [8] reporting that an oxygen-sulfur ylide and benzoic acid can form an α-acyloxy ester compound under the catalysis of a metal catalyst vanadium. Since metal catalysts are expensive and easily pollute the environment, it is necessary to seek green non-metal catalysts. In the past few years, triarylboranes can replace metal catalysts in many cases for catalyzing organic reactions. Tris(pentafluorophenyl)borane is a strong Lewis acid with advantages such as stable chemical properties, strong acidity, and convenient use. B(C6F5)3 has been reported to react with active diazo compounds to generate carbene intermediates or their resonance intermediates, and then carry out insertion and nucleophilic or electrophilic substitution reactions

[10] . Summary of the Invention

[0003] To overcome the defects of the prior art, the present invention realizes a method for synthesizing α -acyloxy esters by O - H insertion using oxosulfonium ylides and carboxylic acid compounds as raw materials and tris(pentafluorophenyl)borane as a catalyst. The purpose of the present invention is to provide a safe, green, and controllable oxyhydrogen insertion reaction of sulfonium ylides, and at the same time, a method for constructing C - O bonds to form α -acyloxy esters. Compared with traditional methods, this method has easily available raw materials and mild conditions, is a mild, safe, and environmentally friendly alternative method, and has broad application prospects.

[0004] The chemical reaction formula of the present invention is as follows:

[0005]

[0006] The preparation steps are as follows:

[0007] (1) Sequentially add oxosulfonium ylides, carboxylic acid compounds, catalyst, and solvent into a clean reactor, place it in an oil bath at 50 °C and stir for 24 h;

[0008] (2) After monitoring the reaction by TLC and finishing, rotary evaporate the solvent under reduced pressure, and purify the residue by silica gel column chromatography to obtain the product;

[0009] (3) In the oxosulfonium ylides in step (1): R1 is hydrogen, methyl, halogen; in the carboxylic acid compounds in step (1): R2 is hydrogen, C1 - C5 alkyl, C1 - C5 alkoxy, halogen, trifluoromethyl, nitro, n = 0, 1, R is ethynyl, vinyl, phenyl ethynyl, styryl; the reaction concentration of the oxosulfonium ylides in step (1) is 0.2 mmol / L, and the molar ratio of oxosulfonium ylides: carboxylic acid compounds: catalyst is 1:2:0.1; the catalyst in step (1) is tris(pentafluorophenyl)borane; the solvent in step (1) is toluene. Specific embodiments

[0010] The following further describes the present invention in combination with specific embodiments, which is helpful for understanding the present invention. However, the scope of the rights of the present invention cannot be limited thereby, and the scope of the rights of the present invention shall be defined by the claims.

[0011] Example 1: Synthesis of Compound 1

[0012]

[0013] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48.0 mg, 0.20 mmol), phenylacetic acid (54.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added in sequence, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was monitored by TLC and completed, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 79.1%. 1 H NMR (400 MHz, Chloroform- d )δ 7.47 (dd, J = 6.8, 2.8 Hz, 2H), 7.39 (dd, J = 5.1, 1.9 Hz, 3H), 7.34 (d, J = 4.1 Hz, 4H),7.31 – 7.26 (m, 1H), 5.94 (s, 1H), 4.17 (dd, J = 16.3, 7.2 Hz, 2H), 3.80 (d, J =8.0 Hz, 2H), 1.19 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 170.97,168.68, 133.83, 133.43, 129.44, 129.19, 128.77, 128.60, 127.57, 127.24,74.92, 61.73, 40.88, 13.97.HRMS(ESI) m / z: Calculated for [C 18 H 18 O4,M+H] + :299.3460, Found: 299.3498.

[0014] Example 2: Synthesis of Compound 2

[0015]

[0016] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48.0 mg, 0.20 mmol), 4-chlorophenylacetic acid (68.2 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added in sequence, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 86.5%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.43 (dt, J = 5.7, 3.5 Hz, 2H), 7.38 (q, J = 3.0 Hz, 3H), 7.29 (d, J = 8.5 Hz, 2H), 7.25 (d, J = 8.5 Hz, 2H), 5.92 (s, 1H), 4.16 (dd, J = 17.5, 7.1 Hz, 2H), 3.76 (d, J = 9.8Hz, 2H), 1.17 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 170.56,168.59, 133.67, 133.23, 131.87, 130.82, 129.29, 128.82, 128.75, 127.59,75.02, 61.80, 40.17, 13.97.HRMS(ESI) m / z: Calculated value for [C 18 H 17 ClO4,M+H] + : 333.7880, Found: 333.7894.

[0017] Example 3: Synthesis of Compound 3

[0018]

[0019] In a clean reactor, α-p-chlorophenyl-β-ethoxycarbonylsulfonium ylide (55.0 mg, 0.20 mmol), phenylacetic acid (54.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added in sequence, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 70.6%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.38 (d, J = 2.3 Hz, 1H), 7.35 (d, J = 5.8 Hz, 3H), 7.33 (d, J = 1.4 Hz, 1H), 7.31 (d, J = 1.1Hz, 3H), 7.30 – 7.24 (m, 1H), 5.89 (s, 1H), 4.14 (dd, J = 13.7, 7.0 Hz, 1H),3.77 (d, J = 5.7 Hz, 2H), 1.17 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 170.78, 168.31, 135.20, 133.28, 132.36, 129.41, 128.99, 128.90, 128.63,127.31, 74.12, 61.91, 40.87, 13.96.HRMS(ESI) m / z: Calculated for [C 18 H 17 ClO4,M+H] + : 333.7880, Found: 333.7888.

[0020] Example 4: Synthesis of Compound 4

[0021]

[0022] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48.0 mg, 0.20 mmol), 4-methylphenylacetic acid (60.0 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was monitored by TLC and completed, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 78.4%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.49 –7.45 (m, 2H), 7.42 – 7.38 (m, 3H), 7.23 (d, J = 7.7 Hz, 2H), 7.15 (d, J = 7.7 Hz,2H), 5.94 (s, 1H), 4.17 (dd, J = 16.6, 7.1 Hz, 2H), 3.76 (d, J = 8.2 Hz, 2H),2.35 (s, 3H), 1.20 (t, J = 7.2 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d ) δ 171.20,168.74, 136.84, 133.88, 130.36, 129.31, 129.30, 129.18, 128.77, 127.59,74.88, 61.72, 40.45, 21.12, 13.97.HRMS(ESI) m / z: Calculated [C 19 H 20 O4,M+H] + : 313.3730, Found: 313.3715.

[0023] Example 5: Synthesis of Compound 5

[0024]

[0025] In a clean reactor, α-p-methylphenyl-β-ethoxycarbonylsulfonium ylide (50.9 mg, 0.20 mmol), phenylacetic acid (54.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 38.7%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.33 (s,1H), 7.31 (d, J = 2.0 Hz, 5H), 7.28 – 7.24 (m, 1H), 7.18 (d, J = 7.9 Hz, 2H),5.88 (s, 1H), 4.14 (dd, J = 19.3, 7.1 Hz, 2H), 3.76 (d, J = 8.5 Hz, 2H), 2.35 (s,3H), 1.17 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 171.04, 168.84,139.19, 133.47, 130.88, 129.47, 129.44, 128.58, 127.56, 127.21, 74.82, 61.66,40.88, 21.26, 13.97.HRMS(ESI)m / z: Calculated for [C 19 H 20 O4,M+H] + :313.3730, Found: 313.3722.

[0026] Example 6: Synthesis of Compound 6

[0027]

[0028] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), 4-tert-butylphenylacetic acid (76.9 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were successively added, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 81.5%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.39 –7.33 (m, 2H), 7.30 – 7.25 (m, 5H), 7.17 (d, J = 8.0 Hz, 2H), 5.84 (s, 1H), 4.06(dd, J = 15.7, 7.1 Hz, 2H), 3.67 (d, J = 8.7 Hz, 2H), 1.22 (s, 9H), 1.07 (t, J =7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 171.21, 168.75, 150.08, 133.89,130.40, 129.18, 129.11, 128.77, 127.58, 125.56, 74.90, 61.72, 40.33, 34.50,31.38, 13.98.HRMS(ESI) m / z: Calculated [C 22 H 26 O4,M+H] + :355.4540, Found: 355.4545.

[0029] Example 7: Synthesis of Compound 7

[0030]

[0031] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), 4-methoxyphenylacetic acid (66.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were successively added, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a pale yellow oily product with a yield of 77.7%.1 H NMR (600 MHz, Chloroform- d ) δ 7.46 –7.44 (m, 2H), 7.39 – 7.36 (m, 3H), 7.24 (d, J = 9.0 Hz, 2H), 6.86 (d, J = 8.6 Hz,2H), 5.92 (s, 1H), 4.15 (dd, J = 29.0, 7.1 Hz, 2H), 3.78 (s, 3H), 3.72 (d, J =16.1 Hz, 2H), 1.18 (t, J = 6.8 Hz,3H). 13 C NMR (151 MHz, Chloroform- d )δ 171.32,168.72, 158.78, 133.82, 130.46, 129.18, 128.76, 127.56, 125.46, 114.00,74.84, 61.71, 55.25, 39.94, 13.96.HRMS(ESI) m / z: Calculated [C 19 H 20 O5,M+H] + : 329.3720, Found: 329.3713.

[0032] Example 8: Synthesis of Compound 8

[0033]

[0034] α-Phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), 4-(trifluoromethyl)phenylacetic acid (81.7 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were successively added to a clean reactor, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 85.6%. 1 H NMR (400 MHz, Chloroform- d )δ 7.59 (d, J= 8.1 Hz, 2H), 7.47 – 7.41 (m, 4H), 7.40 – 7.36 (m, 3H), 5.93 (s, 1H), 4.15(dd, J = 17.9, 7.1 Hz, 2H), 3.84 (d, J = 11.1 Hz, 2H), 1.17 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 170.19, 168.53, 137.40, 137.39, 133.58, 129.85,129.34, 128.83, 127.59, 125.58, 125.55, 125.51, 125.47, 122.80, 75.12, 61.84,40.58, 13.93. 19 F NMR (376 MHz, Chloroform- d )δ -62.56.HRMS(ESI) m / z: Calculated for [C 19 H 17 F3O4, M+H] + : 367.3442, found: 367.3437.

[0035] Example 9: Synthesis of Compound 9

[0036]

[0037] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), 4-nitrophenylacetic acid (72.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 77.8%. 1 H NMR (400 MHz, Chloroform- d )δ 8.19 (d, J =8.3 Hz, 2H), 7.50 (d, J = 8.3 Hz, 2H), 7.44 – 7.41 (m, 2H), 7.40 – 7.37 (m,3H), 5.94 (s, 1H), 4.16 (dd,J = 18.6, 7.1 Hz, 2H), 3.89 (d, J = 11.9 Hz, 2H),1.18 (t, J = 7.2 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d ) δ 169.62, 168.43,147.29, 140.74, 133.40, 130.45, 129.43, 128.88, 127.61, 123.77, 75.25, 61.91,40.54, 13.97.HRMS(ESI) m / z: Calculated for [C 18 H 17 NO6,M+H] + : 344.3430, found: 344.3442.

[0038] Example 10: Synthesis of Compound 10

[0039]

[0040] α-Phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), benzoic acid (48.8 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were successively added to a clean reactor, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 76.3%. 1 H NMR (400 MHz, Chloroform- d ) δ 8.13 (d, J = 7.7 Hz,2H), 7.59 (d, J = 4.6 Hz, 3H), 7.45 (dd, J = 16.5, 7.7 Hz, 5H), 6.15 (s, 1H),4.22 (dd, J = 20.1, 7.1 Hz, 2H), 1.23 (t, J = 7.2 Hz, 3H). 13 C NMR (101 MHz,Chloroform- d) δ 168.82, 165.92, 134.13, 133.48, 129.99, 129.34, 129.24, 128.85, 128.48, 127.65, 75.03, 61.78, 14.04. HRMS(ESI) m / z: Calculated value [C 17 H 16 O4, M+H] + : 285.3190, found: 285.3167.

[0041] Example 11: Synthesis of Compound 11

[0042]

[0043] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), 4-methylbenzoic acid (54.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a colorless oily product with a yield of 82.1% (conversion rate: 79.2%). 1 1H NMR (400 MHz, Chloroform- d ) δ 8.02 (d, J J = 8.0 Hz, 2H), 7.59 (d, J J = 5.4 Hz, 2H), 7.42 (d, J J = 7.0 Hz, 3H), 7.25 (d, J J = 8.1 Hz, 2H), 6.13 (s, 1H), 4.21 (dd, J J = 19.5, 7.1 Hz, 2H), 2.41 (s, 3H), 1.23 (t, J J = 7.1 Hz, 3H). 13 13C NMR (101 MHz, Chloroform- d ) δ 168.91, 165.97, 144.25, 134.25, 130.03, 129.18, 129.17, 128.82, 127.63, 126.59, 74.89, 61.72, 21.75, 14.04. HRMS(ESI) m / z: Calculated value [C 18 H 18O4, M+H] + : 299.3460, Measured value: 299.3488.

[0044] Example 12: Synthesis of Compound 12

[0045]

[0046] In a clean reactor, successively add α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), propiolic acid (28.0 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml), place it in an oil bath at 50 °C and stir for 24 h. After monitoring the completion of the reaction by TLC, evaporate the solvent under reduced pressure, and purify the residue by silica gel column chromatography to obtain a pale yellow oily product with a yield of 61.1%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.50 – 7.44 (m, 2H), 7.42 – 7.38 (m, 3H), 5.97 (s, 1H), 4.20 (dd, J = 18.9, 7.1 Hz, 2H), 2.99 (s, 1H), 1.22 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d ) δ 167.73, 151.84, 132.84, 129.56, 128.89, 127.72, 76.39, 75.85, 74.01, 62.08, 13.97. HRMS(ESI) m / z: Calculated value [C 13 H 12 O4, M+H] + : 233.2430, Measured value: 244.2444.

[0047] Example 13: Synthesis of Compound 13

[0048]

[0049] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), acrylic acid (28.8 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a pale yellow oily product with a yield of 55.5%. 1 H NMR (400 MHz, Chloroform- d ) δ 7.50 (dd, J =6.5, 3.1 Hz, 2H), 7.40 (dd, J = 5.1, 2.0 Hz, 3H), 6.53 (d, J = 17.3 Hz, 1H), 6.25(dd, J = 17.3, 10.4 Hz, 1H), 5.99 (s, 1H), 5.93 (d, J = 10.4 Hz, 1H), 4.20 (dd, J =20.4, 7.1 Hz, 2H), 1.22 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ168.71, 165.38, 133.91, 132.22, 129.22, 128.79, 127.63, 127.56, 74.65, 61.76,14.00.HRMS(ESI) m / z: Calculated value [C 13 H 14 O4,M+H] + :235.2590, Found: 235.2578。

[0050] Example 14: Synthesis of Compound 14

[0051]

[0052] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), phenylpropiolic acid (58.5 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added successively, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a pale yellow oily product with a yield of 89.5%. 1 H NMR (400 MHz, Chloroform- d )δ 7.63 – 7.57(m, 2H), 7.54 (d, J = 4.4 Hz, 1H), 7.52 (d, J = 2.0 Hz, 1H), 7.48 – 7.40 (m, 4H),7.38 (t, J = 7.5 Hz, 2H), 6.04 (s, 1H), 4.23 (dd, J = 19.9, 7.1 Hz, 2H), 1.25 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 168.10, 153.21, 133.20,133.15, 130.91, 129.49, 128.89, 128.62, 127.82, 119.38, 88.02, 80.08, 75.71,62.01, 14.02.HRMS(ESI) m / z: Calculated [C 19 H 16 O4,M+H] + :309.3410, Found: 309.3433.

[0053] Example 15: Synthesis of Compound 15

[0054]

[0055] In a clean reactor, α-phenyl-β-ethoxycarbonylsulfonium ylide (48 mg, 0.20 mmol), cinnamic acid (59.3 mg, 0.40 mmol), tris(pentafluorophenyl)borane (10.2 mg, 0.02 mmol) and toluene (1 ml) were added in sequence, and the mixture was stirred in an oil bath at 50 °C for 24 h. After the reaction was completed as monitored by TLC, the solvent was evaporated under reduced pressure, and the residue was separated and purified by silica gel column chromatography to obtain a pale yellow oily product with a yield of 64.4%. 1 H NMR (400 MHz, Chloroform- d )δ 7.80 (d, J =16.0 Hz, 1H), 7.58 – 7.53 (m, 4H), 7.42 (d, J = 7.5 Hz, 3H), 7.41 – 7.37 (m,3H), 6.59 (d, J = 16.0 Hz, 1H), 6.07 (s, 1H), 4.22 (dd, J = 22.1, 7.1 Hz, 2H),1.24 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, Chloroform- d )δ 168.94, 166.21,146.30, 134.21, 134.10, 130.62, 129.25, 128.96, 128.85, 128.30, 127.72,117.01, 74.70, 61.78, 14.06.HRMS(ESI) m / z: Calculated for [C 19 H 18 O4,M+H] + :311.3570, Found: 311.3596.

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Claims

1. A method for generating α - acyloxy esters from oxosulfonium ylides and carboxylic acid compounds, characterized in that Using an oxygen-sulfur ylide and a carboxylic acid compound as starting materials, with toluene as the solvent, under the action of the non-metallic catalyst tris(pentafluorophenyl)borane, O-H insertion is carried out to synthesize α-acyloxy ester compounds, and its chemical reaction formula is: ， Wherein: R1 is hydrogen, methyl, halogen; R2 is hydrogen, C1-C5 alkyl, C1-C5 alkoxy, halogen, trifluoromethyl, nitro; n=0、1； R is ethynyl, vinyl, phenyl ethynyl, styryl.

2. The method according to claim 1, wherein The following preparation steps are adopted: Add the oxygen-sulfur ylide, carboxylic acid compound, non-metallic catalyst, and solvent into a clean and dry pressure-resistant bottle, seal it, and heat and stir for reaction; after the reaction is completed, remove the solvent under reduced pressure, and separate and purify by silica gel column chromatography to obtain the product.

3. The method according to claim 2, wherein The reaction concentration of the oxygen-sulfur ylide is 0.2 mmol / L, and the molar ratio of the oxygen-sulfur ylide: carboxylic acid compound: catalyst is 1:2:0.

1.

4. The method according to claim 2, wherein The reaction temperature is 50 °C and the reaction time is 24 hours.

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