A wacker type oxidation process for the preparation of methyl ketones

Abstract

The application discloses a Wacker type oxidation preparation method of methyl ketone. The method comprises the following steps: adding a hydrocarbon compound, a palladium catalyst, a ligand and an oxidant into an alcohol solvent, and performing heating treatment under a protective atmosphere to obtain a methyl ketone compound, wherein the oxidant is an Oxone oxidant, and the ligand is 2-phenyl-1H-benzo[d]imidazole. The preparation method provided by the application has high catalytic activity of the catalytic system, and the catalyst loading is as low as 0.1-1 mol%, thereby greatly reducing the cost of noble metals. The ligand used has a simple structure and is convenient to synthesize, and high catalytic activity and high regioselectivity are realized. The Oxone used as the green oxidant has good water solubility and friendly by-products, the reaction is performed at 50-60 DEG C under normal pressure, the solvent used is cheap and low-toxic, and the condition is mild, safe and easy to scale up. The method has a wide applicable range of substrates, excellent functional group compatibility, single product and simple separation and purification.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a Wacker-type oxidation method for preparing methyl ketones. Background Technology

[0002] The Wacker oxidation reaction is an important method for converting alkenes into methyl ketones. The classic Wacker process uses... Bimetallic catalytic systems, using oxygen as an oxidant, suffer from drawbacks such as low oxygen solubility, limited mass transfer, and safety risks. To overcome these limitations, researchers have developed various novel catalytic systems, such as TBHP. Ligand-mediated oxidation under aerobic conditions. However, TBHP readily initiates free radical side reactions. Excessive oxidizing capacity can lead to over-oxidation, and the oxygen system will still be troubled by mass transfer and safety issues.

[0003] Oxone, as a green, stable, and water-soluble oxidant, has been widely used in reactions such as epoxidation. However, its application in Wacker oxidation faces unique challenges: its strong oxidizing properties may lead to over-oxidation and deactivation of palladium catalysts, and its water solubility presents compatibility issues with traditional non-aqueous phase conditions. Therefore, how to effectively utilize oxone in Wacker oxidation while maintaining catalyst activity and selectivity has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the present invention aims to provide a Wacker-type oxidation method for preparing methyl ketones to solve the aforementioned technical problems. The Wacker-type oxidation method for preparing methyl ketones provided by the present invention is a method for efficiently and selectively oxidizing hydrocarbon compounds (preferably terminal olefins) to methyl ketones under mild conditions, utilizing a palladium(II) catalyst and a novel nitrogen ligand for synergistic catalysis, and using Oxone as a green oxidant.

[0005] According to a first aspect of the present invention, the present invention provides a Wacker-type oxidation method for preparing methyl ketones, comprising the following steps: adding a hydrocarbon compound, a palladium catalyst, a ligand, and an oxidant to an alcohol solvent, and performing heat treatment under a protective atmosphere to obtain a methyl ketone compound; The oxidant is Oxone (potassium persulfate); The ligand is 2-phenyl-1H-benzo[d]imidazole.

[0006] In some embodiments, the hydrocarbon compound is at least one of the following structural formulas: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0007] In some embodiments, the palladium catalyst (palladium salt) is at least one of palladium acetate, palladium chloride, palladium trifluoroacetate, palladium acetate hydrate, palladium chloride hydrate, and palladium trifluoroacetate hydrate.

[0008] In some embodiments, the palladium catalyst is (Palladium acetate). Palladium acetate exhibits good solubility in alcohol solvents, which is beneficial for forming a homogeneous catalytic system; its acetate ion, as a leaving group, readily dissociates during the catalytic cycle, promoting the formation of active palladium species; simultaneously, palladium acetate demonstrates excellent coordination compatibility with the 2-phenyl-1H-benzo[d]imidazole ligand, forming a stable catalytic active center. In contrast, if palladium chloride ( Chloride ions may strongly coordinate with palladium, inhibiting effective ligand coordination and reducing catalytic activity; palladium trifluoroacetate ( While it also has good activity, it is expensive and trifluoroacetate may cause side reactions in the reaction system; heterogeneous catalysts such as palladium on carbon (Pd / C) are difficult to achieve efficient homogeneous catalysis due to low dispersion of active sites and limited mass transfer.

[0009] In some embodiments, the structural formula of the 2-phenyl-1H-benzo[d]imidazole is shown below;

[0010] In some embodiments, the alcohol solvent is a fatty alcohol; the fatty alcohol has a chemical formula with 1-4 carbon atoms (i.e., the alcohol solvent is a C1-C4 fatty alcohol).

[0011] In some embodiments, the alcohol solvent is ethanol or methanol.

[0012] In some embodiments, the alcohol solvent is ethanol.

[0013] In some embodiments, the molar amount of the palladium catalyst is from 0.05 mol% to 5 mol% of the molar amount of the hydrocarbon compound.

[0014] In some embodiments, the molar amount of the palladium catalyst is 0.1 mol% to 1 mol% of the molar amount of the hydrocarbon compound.

[0015] In some embodiments, the molar ratio of the ligand to the palladium catalyst is from 0.5:1 to 5:1.

[0016] In some embodiments, the molar ratio of the ligand to the palladium catalyst is 1:1.

[0017] In some embodiments, the molar amount of the oxidant is 1.0 to 3.0 times the molar amount of the hydrocarbon compound (the amount of oxidant is 1.0 to 3.0 equivalents of the molar amount of the terminal olefin).

[0018] In some embodiments, the molar amount of the oxidant is 1.5 times the molar amount of the hydrocarbon compound (the amount of oxidant is 1.5 equivalents of the molar amount of the terminal olefin).

[0019] In some embodiments, the molar volume ratio of the hydrocarbon compound to the alcohol solvent is 0.1-0.5 mmol / mL.

[0020] In some embodiments, the protective atmosphere is at least one of nitrogen, argon, neon, and helium; the temperature of the heat treatment is 40-80°C, and the heat treatment time is 2-24 hours.

[0021] In some embodiments, the heat treatment temperature is 50-60°C and the heat treatment time is 6-12 hours.

[0022] In some embodiments, the heat treatment is performed under stirring conditions.

[0023] In some embodiments, the preparation method provided by the present invention uses 2-phenyl-1H-benzis[d]imidazole as a ligand and palladium acetate. It constitutes a highly efficient catalytic system, using Oxone as a green oxidant, to achieve highly selective oxidation of terminal olefins under mild conditions in ethanol.

[0024] The method for preparing efficient, economical, green, and highly selective terminal olefin oxidation provided by this invention is a method for hydrocarbon oxidation that is efficient, economical, green, and highly selective, and can overcome the problems of high catalyst loading, environmentally unfriendly oxidants, and harsh reaction conditions in existing technologies.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The Wacker-type oxidation preparation method of methyl ketones provided by the present invention uses a catalyst with high efficiency and low dosage. The Pd(OAc)2 and 2-phenyl-1H-benzi[d]imidazolium ligand catalytic system used in the embodiments of the present invention has high activity and the catalyst loading can be as low as 0.1-1 mol%, which significantly reduces the cost of using precious metals. 2. Green and environmentally friendly oxidant: The Wacker-type oxidation preparation method of methyl ketone provided by this invention uses Oxone as the terminal oxidant, which has the advantages of good water solubility, high stability, strong oxidizing power, and environmentally friendly by-products after reaction, which meets the requirements of green chemistry development.

[0026] 3. Simple ligand structure and superior performance: The 2-phenyl-1H-benzis[d]imidazolium ligand used in the Wacker-type oxidation preparation method of methyl ketones provided by this invention is simple to synthesize and can effectively regulate the electron and space environment of the palladium center to achieve high activity and high regioselectivity (Markovnikov selectivity).

[0027] 4. Mild reaction conditions and simple operation: In the Wacker-type oxidation preparation method of methyl ketones provided by the present invention, the reaction is carried out at a mild temperature (such as 50-60℃) and normal pressure, and inexpensive and low-toxicity solvents such as ethanol are used. The process has good safety and is easy to scale up.

[0028] 5. Wide range of applicable substrates and good functional group compatibility: The Wacker-type oxidation preparation method for methyl ketones provided by this invention can achieve efficient conversion of terminal alkenes containing various functional groups such as electron-donating groups, halogens, ethers, and esters, demonstrating excellent functional group tolerance and providing possibilities for the later modification of complex molecules.

[0029] 6. High regioselectivity: The Wacker-type oxidation method for preparing methyl ketones provided by this invention exhibits high Markovnikov selectivity for the generation of methyl ketones from terminal alkenes, with good product singleness. While improving reaction selectivity, it also significantly simplifies the product separation and purification process. Attached Figure Description

[0030] Figure 1 This is the general reaction formula for the Wacker-type oxidation preparation method of methyl ketones in the embodiments of the present invention.

[0031] Figure 2 The diagram shows the structural formula of the product obtained from the oxidation reaction of the substrate in the Wacker-type oxidation preparation method of methyl ketones in Examples 3-30, along with the corresponding yield results. Detailed Implementation

[0032] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1 A Wacker-type oxidation method for preparing methyl ketones includes the following steps: adding a hydrocarbon compound (1.0 mmol), a palladium catalyst (0.01 mmol), a ligand, and an oxidant (1.5 mmol) to an alcohol solvent (4 mL), mixing well, and heating under a protective atmosphere and stirring to obtain the methyl ketone compound; The oxidant is an Oxone oxidant; The ligand is 2-phenyl-1H-benzis[d]imidazole; The hydrocarbon compound is p-methylstyrene; the palladium catalyst is Pd(OAc)2; The alcohol solvent is ethanol. The molar amount of the palladium catalyst is 1 mol% of the molar amount of the hydrocarbon compound; the molar ratio of the oxidant to the hydrocarbon compound is 1.5:1. The molar ratio of the ligand to the palladium catalyst is 1:1; The molar ratio of the hydrocarbon compound to the alcohol solvent is 0.25:1 mmol / mL.

[0034] The protective atmosphere is a nitrogen atmosphere; The heat treatment temperature is 50°C, and the heat treatment time is 6 hours.

[0035] Reference Figure 1 As shown in the reaction formula, Example 1 used p-methylstyrene as a model substrate. Under the conditions of using Pd(OAc)2 (1 mol%) as catalyst, Oxone (1.5 equivalents of p-methylstyrene) as solvent and ethanol as solvent, the product was separated by column chromatography (purified by rapid silica gel column chromatography, with petroleum ether / ethyl acetate as mobile phase) with a yield of 95%.

[0036] After the reaction (heat treatment) was completed, the resulting reaction solution was concentrated, and the residue was purified by rapid silica gel column chromatography. The chromatographic purification method was performed according to the procedure described in Section 0512 Column Chromatography in Part IV of the 2020 edition of the Chinese Pharmacopoeia. The specific procedures were as follows: 200-300 mesh silica gel was used as the packing material, and the column was packed using a wet method; the sample was dissolved in ethyl acetate, mixed, and then loaded onto the column using a dry method; elution was performed using a mixed solution of petroleum ether and ethyl acetate as the mobile phase, with the mobile phase ratio predetermined by thin-layer chromatography (TLC) based on the polarity of the target product, and the volume ratio of petroleum ether to ethyl acetate was 20:1; the fraction containing the target product was collected, combined, and concentrated under reduced pressure to obtain the pure product. The product yield was calculated based on the ratio of the mass of the purified product obtained to the theoretical yield. The same applies below.

[0037] Comparative Example 1 (No Ligand Control) Comparative Example 1 was essentially the same as Example 1, except that no ligand was added in Comparative Example 1; the reaction was carried out under ligand-free conditions. All other conditions were the same as in Example 1. Specifically, p-methylstyrene (1.0 mmol), Pd(OAc)₂ (0.01 mmol), and Oxone (1.5 mmol) were added to ethanol (4 mL), and the mixture was heated under a nitrogen atmosphere (50°C for 6 hours). After 6 hours of reaction, the product was separated by column chromatography, and the yield of this comparative example was 9%.

[0038] Comparative Example 2 (Other Ligand Controls) Comparative Example 2 was essentially the same as Example 1, except that 2,2'-bipyridine was used as the ligand instead of 2-phenyl-1H-benzis[d]imidazole in Comparative Example 2, while the other conditions were the same as in Example 1. After reacting for 6 hours, the product was separated by column chromatography, with a yield of 15%.

[0039] Comparative Example 3 (Other oxidizing agents as control) Comparative Example 3 was essentially the same as Example 1, except that Oxone was replaced with H2O2 solution (30 wt%), while the other conditions were the same as in Example 1. After reacting for 6 hours, the product was separated by column chromatography, with a yield of 6%.

[0040] Comparative Example 4 (Mixed Solvent Control) Comparative Example 4 was essentially the same as Example 1, except that it used a mixture of ethanol and water as the solvent (ethanol to water volume ratio of 2:1), with all other conditions the same as in Example 1. After 6 hours of reaction, the product was separated by column chromatography, with a yield of 58%.

[0041] Comparative Examples 5-13 (other ligand screening controls) are basically the same as Example 1, except that the ligands used are different. The other conditions are the same as those in Example 1. The ligand information and corresponding product yields of Comparative Examples 5-13 are shown in Table 1 below.

[0042] Table 1 Comparison of Ligand Screening

[0043] Ligand screening analysis: The results of the comparative examples (as shown in Table 1 and Comparative Examples 1-2) indicate that nitrogen-containing ligands with different structures significantly affect the reaction yield. The yield without ligands was only 9% (Comparative Example 1), while the yield increased to varying degrees after the addition of ligands. Among these, the yields of bipyridine ligands (Comparative Examples 2, 5-8) ranged from 15% to 55%. The methyl substitution position significantly affected the ligand activity, with 4,4'-dimethyl substitution (Comparative Example 7) yielding a higher yield (47%) than other substitution positions. Among pyridine-benzo[d]heterocyclic ligands, the yields of 2-(2-pyridyl)benzo[d]oxazole (Comparative Example 9) and 2-(2-pyridyl)-1H-benzo[d]imidazole (Comparative Example 10) were 58% and 49%, respectively. However, when the pyridine linkage position was changed to the 4-position (Comparative Example 13), the yield plummeted to below 10%, indicating that the coordination configuration is crucial to catalytic activity.

[0044] Of particular note is the achievement of a yield of 95% when 2-phenyl-1H-benzi[d]imidazole (Example 1) was used as the ligand, significantly outperforming all other tested ligands. This ligand differs structurally from 2-(2-pyridyl)-1H-benzi[d]imidazole (Comparative Example 10) only in that the pyridine ring is replaced by a benzene ring, yet the yield nearly doubled from 49% to 95%. This unexpected finding suggests that the introduction of the benzene ring into 2-phenyl-1H-benzi[d]imidazole may alter the electronic effects and spatial configuration of the ligand, creating a more favorable coordination environment with the palladium center, thereby significantly improving catalytic efficiency.

[0045] In summary, 2-phenyl-1H-benzis[d]imidazole as a ligand has a significant and obvious promoting effect on this catalytic system, and its effect is far superior to that of conventional bipyridine ligands and other pyridine-benzo[d]heterocyclic ligands.

[0046] The technical effects of Example 1 and Comparative Examples 1-4 are compared in Table 2 below.

[0047] Table 2 Comparison of Technical Effects

[0048] As shown in Table 2, by comparing Comparative Examples 1-4 with Example 1, the following conclusions can be drawn: 1. The key role of ligands: Comparative Example 1 shows that the reaction yield without ligands is only 9%, which is much lower than 95% in Example 1, indicating that 2-phenyl-1H-benzis[d]imidazole ligands have a decisive promoting effect on catalytic activity.

[0049] 2. Ligand structure specificity: In Comparative Example 2, the yield was only 15% when the classic nitrogen ligand 2,2'-bipyridine was used instead of the ligand of the present invention, indicating that ordinary nitrogen ligands cannot effectively activate the palladium center. However, the 2-phenyl-1H-benzis[d]imidazole selected in this invention has a unique coordination environment and electronic effects, which play a key role in the activity and selective regulation of the palladium center, and is an obvious optimization result.

[0050] 3. The selectivity advantage of the oxidant: In Comparative Example 3, with Replacing oxone as the oxidant resulted in a sharp drop in yield to 6%. (Note:) Excessive oxidizing power leads to over-oxidation of olefins, while oxones are more selective and compatible under mild conditions.

[0051] 4. Synergistic effect of solvent: In Comparative Example 4, when pure ethanol was replaced by a mixed solvent of ethanol / water (volume ratio of 2:1), the yield decreased to 58%, indicating that the presence of the aqueous phase reduced the catalyst activity and product selectivity, further verifying the superiority of pure alcohol solvent in the system of this invention.

[0052] In summary, the ternary system of 2-phenyl-1H-benzo[d]imidazolium ligand – Oxone oxidant – pure alcohol solvent used in this invention exhibits a significant synergistic effect. Specifically, when any key component (ligand) is missing or replaced with other commonly used components (such as bipyridine ligand, ... When oxidizing agents and mixed solvents were used, the yields of the target products all decreased significantly (from 95% to 9%, 15%, 6%, and 58%, respectively). This indicates that the specific ligand, oxidant, and solvent combination selected in the Wacker-type oxidation preparation method of methyl ketones provided by this invention plays an indispensable key role in achieving efficient and highly selective Wacker-type oxidation reactions.

[0053] Example 2 A Wacker-type oxidation method for preparing methyl ketones includes the following steps: adding a hydrocarbon compound (1.0 mmol), a palladium catalyst (0.01 mmol), a ligand, and an oxidant (1.5 mmol) to an alcohol solvent (4 mL), mixing well, and heating under a protective atmosphere and stirring to obtain the methyl ketone compound; The oxidant is an Oxone oxidant; The ligand is 2-phenyl-1H-benzis[d]imidazole; The hydrocarbon compound is p-methylstyrene; the palladium catalyst is Pd(OAc)2; The alcohol solvent is ethanol. The molar amount of the palladium catalyst is 1 mol% of the molar amount of the hydrocarbon compound; the molar ratio of the oxidant to the hydrocarbon compound is 1.5:1. The molar ratio of the ligand to the palladium catalyst is 1:1; The molar ratio of the hydrocarbon compound to the alcohol solvent is 0.25:1 mmol / mL.

[0054] The protective atmosphere is a nitrogen atmosphere; To investigate the effects of heat treatment temperature and time on the reaction, a series of parallel experiments were conducted in Example 2. The heat treatment temperatures and times for each group of parallel experiments are shown in Table 3 below.

[0055] Table 3. Effects of Temperature and Time on Reaction

[0056] As shown in Table 3, the optimal yield (1, 91.4%) can be obtained at a reaction temperature of 50℃ under the same reaction time. As the temperature increases to 60℃ and above, the yield shows a decreasing trend, indicating that excessively high temperatures may lead to an increase in side reactions or a decrease in catalyst stability.

[0057] At the same temperature, reaction time has a significant impact on yield. Taking 50°C as an example, the yield is 95% after 6 hours of reaction (No. 5), while the yield is 91.4% after 12 hours of reaction (No. 1). This indicates that the reaction is essentially completed within 6 hours, and extending the reaction time does not significantly contribute to the yield increase; on the contrary, it slightly reduces the yield. Considering both reaction efficiency and energy consumption, 6 hours of reaction at 50°C is the optimal condition, which can obtain the highest yield (95%) in a shorter time. This condition is consistent with the condition used in Example 1.

[0058] Example 3 Based on the optimal ligand (2-phenyl-1H-benzi[d]imidazole), oxidant (Oxone), and solvent (ethanol) determined in Example 1, the effects of ligand dosage, catalyst dosage, and oxidant dosage on the reaction were further investigated using p-methylstyrene as a model substrate. All experiments were conducted at 50°C for 6 hours (heat treatment conditions), with other procedures the same as in Example 1.

[0059] 1. Optimization of ligand dosage (molar ratio of ligand to palladium catalyst) With a fixed amount of palladium catalyst (1 mol% relative to the substrate hydrocarbon) and oxidant (1.5 equivalents relative to the substrate hydrocarbon), the molar ratio of ligand to palladium catalyst was varied to investigate the effect of ligand amount on the reaction. The results are shown in Table 4.

[0060] Table 4. Screening Results of Ligand Equivalent

[0061] Note: The ligand-free data in Table 4 are from Comparative Example 1. Table 4 shows that the amount of ligand has a significant impact on the reaction yield. Without ligand, the yield is only 9%; the yield reaches its highest level (94%) when the ligand:palladium catalyst molar ratio is 1:1; as the ligand ratio increases to 3:1, the yield decreases slightly (90%); further increasing to 5:1, the yield drops significantly to 70%, indicating that excess ligand may compete with the palladium center for coordination, affecting catalytic efficiency. Considering all factors, the preferred molar ratio of ligand to palladium catalyst is 1:1 to 3:1, more preferably 1:1 to 2:1, and most preferably 1:1.

[0062] 2. Optimization of Palladium Catalyst Dosage With the ligand (2-phenyl-1H-benzis[d]imidazole) at a fixed amount of 1 mol% (relative to the substrate hydrocarbon compound) and the oxidant at a fixed amount of 1.5 equivalents (relative to the substrate hydrocarbon compound), the effect of the amount of palladium catalyst (Pd(OAc)2) on the reaction was investigated by changing the molar percentage of palladium catalyst relative to the substrate. The results are shown in Table 5.

[0063] Table 5. Results of Catalyst Equivalent Screening

[0064] Table 5 shows that the amount of palladium catalyst has a significant impact on the reaction efficiency. Without palladium catalyst, the reaction does not occur at all; the yield reaches its highest level (95%) when the palladium catalyst content is 1.0 mol%. As the palladium catalyst content increases to 3.0 mol%, the yield decreases to 82%; further increasing to 5.0 mol%, the yield decreases further to 64%. This may be due to high palladium concentrations causing metal aggregation and deactivation or promoting side reactions. Considering both catalytic efficiency and economy, the preferred molar amount of palladium catalyst is 1.0 mol% to 3.0 mol%, more preferably 1.0 mol% to 2.0 mol%, and most preferably 1.0 mol%.

[0065] 3. Optimization of oxidant dosage With the amount of palladium catalyst (Pd(OAc)2) fixed at 1 mol% (0.01 mmol, 1 mol% relative to the molar amount of the substrate hydrocarbon compound) and the molar ratio of ligand to palladium catalyst at 1:1 (0.01 mmol), the effect of the amount of oxidant on the reaction was investigated by changing the equivalence of Oxone relative to the substrate hydrocarbon compound. The results are shown in Table 6.

[0066] Table 6. Screening Results of Oxidant Equivalent

[0067] Table 6 shows that the amount of oxidant has a significant impact on the reaction yield. When the amount of oxidant is 0.5 equivalents, the yield is only 34%, indicating that insufficient oxidant hinders the catalytic cycle. When the amount is increased to 1.0 equivalents, the yield increases significantly to 84%; it reaches its highest level (95%) at 1.5 equivalents. When the amount is further increased to 2.0 equivalents and 3.0 equivalents, the yield decreases slightly (89% and 86%, respectively), possibly due to excessive oxidant causing over-oxidation of the palladium catalyst or triggering side reactions. Considering all factors, the molar amount of oxidant is preferably 1.0 to 3.0 times the molar amount of hydrocarbon compound, more preferably 1.0 to 2.0 times, and most preferably 1.5 times.

[0068] Optimal Condition Screening: After determining 2-phenyl-1H-benzi[d]imidazole as the optimal ligand, Oxone as the optimal oxidant, and pure ethanol as the optimal solvent, the temperature, time, and other conditions were systematically optimized. The optimal conditions after screening were: Pd(OAc)2 (1 mol%), 2-phenyl-1H-benzi[d]imidazole (1 mol%), Oxone (1.5 equivalents), ethanol (4 mL), and reaction at 50℃ for 6 hours.

[0069] Under the determined optimal reaction conditions ( Oxidation reactions were carried out on terminal alkenes with different substitutions (1 mol% 2-phenyl-1H-benzo[d]imidazole, 1 mol% Oxone, 1.5 equivalents, 4 mL ethanol, reaction at 50°C for 6 hours) to investigate the substrate applicability and functional group tolerance. Specific examples and results are described below.

[0070] Example 4 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ia are prepared. Details are as follows.

[0071]

[0072] A Wacker-type oxidation method for preparing methyl ketones includes the following steps: A magnetic stir bar (for stirring during subsequent heating), styrene (1.0 mmol), palladium acetate (0.01 mmol), 2-phenyl-1H-benzo[d]imidazole (0.01 mmol), Oxone (1.5 mmol), and ethanol (4 mL) are added to a 25 mL sealed tube. Nitrogen purging (replacing the atmosphere in the sealed tube with nitrogen) is performed, and the mixture is heated and stirred in an oil bath at 50 °C for 6 hours. After the reaction is complete, petroleum ether / ethyl acetate is used as the mobile phase, and the product is purified by rapid silica gel column chromatography. The structural formula of the product is shown in Formula Ia, with a yield of 86%. (Refer to...) Figure 2 As shown (the same applies below). The structure of the product (the compound shown in formula Ia) is characterized as follows: a colorless oily liquid. 1 H NMR (400 MHz, CDCl3) δ 8.00 (d, J = 8.0 Hz, 2H), 7.60 (dd, J =10.9, 3.8 Hz, 1H), 7.50 (t, J = 7.6 Hz, 2H), 2.64 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 198.30, 137.21, 133.22, 128.68, 128.41, 26.74.HRMS (ESI) m / z calcd.for C8H8O [M+H]+ 121.0648, found 121.0650. Example 5 This embodiment provides a method for preparing ketone compounds, by which compounds as shown in Formula Ib are prepared.

[0073]

[0074] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with p-methylstyrene, and the yield of the product is 96%. The structure of the product (the compound shown in Formula Ib) is characterized as follows: colorless liquid. 1 HNMR (400 MHz, CDCl3) δ 7.90 (d, J = 7.8 Hz, 2H), 7.29 (d, J = 7.8 Hz, 2H), 2.62 (s, 3H), 2.45 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 198.04, 144.02, 134.81,129.36, 128.57, 26.67, 21.77.HRMS (ESI) m / z calcd. for C9H 10 O [M+H]+ 135.0804, found 135.0809. Example 6 This embodiment provides a method for preparing ketone compounds, which is a method for preparing compounds as shown in Formula Ic.

[0075]

[0076] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-tert-butylstyrene, and the yield of the product is 95%. The structure of the compound represented by Formula Ic is characterized as follows: a colorless oily liquid. 1 H NMR (400 MHz, CDCl3) δ 7.95 (s, 1H), 7.93 (s, 1H), 7.52 (s, 1H), 7.50 (s, 1H), 2.62 (s, 3H), 1.38 (s, 9H). 13 C NMR (101 MHz, CDCl3) δ 198.01, 156.94, 134.72,128.41, 125.63, 35.23, 31.21, 26.69.HRMS (ESI) m / z calcd. for C 12 H 16 O [M+H]+177.1274, found 177.1282. Example 7 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Id are prepared.

[0077]

[0078] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-methoxystyrene, and the yield of the product is 88%. The structural characterization of the product (the compound shown in Formula Id) is as follows: white crystals. 1 HNMR (400 MHz, CDCl3) δ 7.96 (d, J = 8.4 Hz, 2H), 6.96 (d, J = 8.5 Hz, 2H), 3.89 (s, 3H), 2.58 (s, 3H).13 C NMR (101 MHz, CDCl3) δ 196.92, 163.57, 130.69,130.40, 113.77, 55.56, 26.45.HRMS (ESI) m / z calcd. for C9H 10 O2[M+H]+ 151.0754, found 151.0761. Example 8 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ie are prepared.

[0079]

[0080] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with p-phenoxystyrene, and the yield of the product is 87%. The structural characterization of the product (the compound shown in Formula Ie) is as follows: pale yellow powder. 1 H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 8.5 Hz, 2H), 7.43 (t, J = 7.7 Hz, 2H), 7.23 (t, J = 7.2 Hz, 1H), 7.10 (d, J = 8.2 Hz, 2H), 7.03 (d, J = 8.5 Hz, 2H),2.60 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.89, 162.10, 155.57, 131.96,130.71, 130.17, 124.73, 120.28, 117.37, 26.58.HRMS (ESI) m / z calcd. forC 14 H 12 O2[M+H]+ 213.0920, found 213.0920. Example 9 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula If are prepared.

[0081]

[0082] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with N,N-dimethyl-4-vinylaniline, and the yield of the product is 21%. The structure of the product (the compound shown in Formula If) is characterized as follows: a pale yellow powder. 1H NMR (400 MHz, CDCl3) δ 7.91 (d, J = 8.4 Hz, 2H), 6.69 (d, J = 8.5Hz, 2H), 3.09 (s, 6H), 2.54 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.54, 153.48,130.64, 125.47, 110.72, 40.17, 26.13.HRMS (ESI) m / z calcd. for C 10 H 13 NO[M+H]+164.1076, found 164.1075. Example 10 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ig are prepared.

[0083]

[0084] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-acetoxystyrene, and the yield of the product is 70%. The structure of the product (the compound shown in Formula Ig) is characterized as follows: white solid. 1 H NMR (400 MHz, CDCl3) δ 8.02 (d, J = 8.4 Hz, 2H), 7.22 (d, J = 8.4 Hz, 2H), 2.63 (s, 3H), 2.35 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 197.07, 169.02, 154.46,134.81, 130.07, 121.89, 26.72, 21.26.HRMS (ESI) m / z calcd. for C 10 H 13 NO[M+H]+179.0258, found 179.0554. Example 11 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ih are prepared.

[0085]

[0086] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-fluorostyrene, and the yield of the product is 87%. The structure of the product (the compound shown in Formula Ih) is characterized as follows: a yellow oily liquid. 1 HNMR (400 MHz, CDCl3) δ 8.01 (dd, J = 7.6, 5.5 Hz, 2H), 7.15 (t, J = 8.1 Hz, 2H), 2.61 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.61, 165.86(d, J = 255.5 Hz), 133.68(d, J = 3.03Hz) 131.06(d, J = 90.9 Hz), 115.76(d, J = 22.22 Hz), 26.65. 19 F NMR (376 MHz, CDCl3) δ -105.32.HRMS (ESI) m / z calcd. for C8H7FO [M+H]+ 139.0554, found 139.0559. Example 12 This embodiment provides a method for preparing ketone compounds, by which compounds as shown in Formula Ii are prepared.

[0087]

[0088] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-chlorostyrene, and the yield of the product is 93%. The structure of the product (the compound shown in Formula Ii) is characterized as follows: a colorless oily liquid. 1 HNMR (400 MHz, CDCl3) δ 7.92 (d, J = 8.0 Hz, 2H), 7.45 (d, J = 8.0 Hz, 2H), 2.61 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.96, 139.65, 135.50, 129.83,128.98, 26.67.HRMS (ESI) m / z calcd. for C8H7 35.5 ClO [M+H]+ 155.0258, found155.0260. Example 13 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ij are prepared.

[0089]

[0090] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-bromostyrene, and the yield of the product is 90%. The structural characterization of the product (the compound shown in Formula Ij) is as follows: white flaky crystals. 1 HNMR (400 MHz, CDCl3) δ 7.85 (d, J = 7.4 Hz, 2H), 7.64 (d, J = 7.4 Hz, 2H), 2.62 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 197.17, 135.93, 132.02, 129.97,128.44, 26.69.HRMS (ESI) m / z calcd. for C8H7 79 BrO [M+H]+ 198.9753, found198.9755. Example 14 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ik are prepared.

[0091]

[0092] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-vinylbenzylnitrile, and the yield of the product is 40%. The structure of the product (the compound shown in Formula Ik) is characterized as follows: a pale yellow solid. 1 HNMR (400 MHz, CDCl3) δ 8.08 (d, J = 7.9 Hz, 2H), 7.81 (d, J = 8.0 Hz, 2H), 2.68 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.69, 140.01, 132.64, 128.82,118.05, 116.51, 26.90.HRMS (ESI) m / z calcd. for C9H7NO [M+H]+ 146.0602, found146.0602. Example 15 This embodiment provides a method for preparing ketone compounds, by which compounds as shown in Formula Il are prepared.

[0093]

[0094] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-(trifluoromethyl)styrene, and the yield of the product is 9%. The structure of the product (the compound shown in Formula 11) is characterized as follows: a pale yellow solid. 1 H NMR (400 MHz, CDCl3) δ 8.09 (d, J = 8.1 Hz, 2H), 7.76 (d, J = 8.0 Hz, 2H), 2.68 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 197.16, 139.78, 134.6(q, J = 99.0Hz), 128.76, 125.8(q, J = 34 Hz), 123.73(d, J = 10.1Hz), 26.93. 19 F NMR (376MHz, CDCl3) δ -63.11.HRMS (ESI) m / z calcd. for C9H7F3O [M+H]+ 189.0522, found189.0521. Example 16 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Im are prepared.

[0095]

[0096] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-nitrostyrene, and the yield of the product is 40%. The structure of the product (as shown in Im) is characterized as follows: pale yellow powder. 1 HNMR (400 MHz, CDCl3) δ 8.35 (d, J = 7.2 Hz, 2H), 8.16 (d, J = 7.2 Hz, 2H), 2.73 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.46, 150.46, 141.47, 129.43,123.98, 27.12.HRMS (ESI) m / z calcd. for C8H7NO3[M+H]+ 166.0499, found166.0500. Example 17 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula In are prepared.

[0097]

[0098] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 4-vinylbiphenyl, and the yield of the product is 42%. The structure of the product (the compound shown in Formula In) is characterized as follows: white solid. 1 HNMR (400 MHz, CDCl3) δ 8.08 (d, J = 7.6 Hz, 2H), 7.73 (d, J = 7.5 Hz, 2H), 7.67 (d, J = 7.9 Hz, 2H), 7.52 (t, J = 7.4 Hz, 2H), 7.44 (t, J = 7.3 Hz, 1H),2.68 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 197.91, 145.91, 140.00, 135.97,129.09, 129.05, 128.37, 127.41, 127.36, 26.82.HRMS (ESI) m / z calcd. forC 14 H 12 O[M+H]+ 197.0961, found 197.0969. Example 18 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Io are prepared.

[0099]

[0100] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 3-methylstyrene, and the yield of the product is 88%. The structure of the product (the compound represented by formula Io) is characterized as follows: a yellow oily liquid. 1 HNMR (400 MHz, CDCl3) δ 7.79 (d, J = 10.6 Hz, 2H), 7.45 – 7.33 (m, 2H), 2.62(s, 3H), 2.44 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 198.54, 138.45, 137.23,133.97, 128.88, 128.54, 125.68, 26.78, 21.44.HRMS (ESI) m / z calcd. for C9H 10 O[M+H]+ 135.0804, found 135.0806. Example 19 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ip are prepared.

[0101]

[0102] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 3-fluorostyrene, and the yield of the product is 40%. The structure of the product (the compound shown in Formula Ip) is characterized as follows: a pale yellow oily liquid. 1 H NMR (400 MHz, CDCl3) δ 7.77 (d, J = 7.7 Hz, 1H), 7.66 (d, J = 9.4 Hz, 1H), 7.48 (dd, J = 14.2, 7.2 Hz, 1H), 7.29 (t, J = 8.2 Hz, 1H), 2.63 (s, 3H). 13 CNMR (101 MHz, CDCl3) δ 196.93, 162.95(d, J = 249.5 Hz), 139.26(d, J = 6.0Hz), 130.38(d, J = 8.0 Hz), 124.25(d, J = 3.0Hz), 120.25(d, J = 22.2 Hz), 115.06 (d, J = 22.2 Hz), 26.82. 19 F NMR (376 MHz, CDCl3) δ -111.96.HRMS (ESI) m / z calcd. for C8H7FO [M+H]+ 139.0554, found 139.0555. Example 20 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Iq are prepared.

[0103]

[0104] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-methylstyrene, and the yield of the product is 66%. The structure of the product (the compound shown in Formula Iq) is characterized as follows: a pale yellow oily liquid. 1H NMR (400 MHz, CDCl3) δ 7.73 (d, J = 7.7 Hz, 1H), 7.42 (t, J = 7.5 Hz, 1H), 7.30 (t, J = 9.7 Hz, 2H), 2.62 (s, 3H), 2.57 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 201.90, 138.56, 137.74, 132.17, 131.65, 129.49, 125.82, 29.69,21.73.HRMS (ESI) m / z calcd. for C9H 10 O [M+H]+ 135.0804, found 135.0807. Example 21 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ir are prepared.

[0105]

[0106] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-fluorostyrene, and the yield of the product is 27%. The structure of the product (the compound shown in Formula Ir) is characterized as follows: a pale yellow oily liquid. 1 H NMR (400 MHz, CDCl3) δ 7.90 (t, J = 7.6 Hz, 1H), 7.55 (dt, J = 13.3, 3.6Hz, 1H), 7.25 (t, J = 7.6 Hz, 1H), 7.16 (dd, J = 11.0, 8.5 Hz, 1H), 2.67 (d,J = 4.8 Hz, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.07(d, J = 3.0 Hz), 162.34(d, J= 256.5 Hz), 134.80(d, J = 8.0 Hz), 130.68(d, J = 2.0 Hz), 125.78(d, J = 12.2Hz), 124.47(d, J = 4.0 Hz), 116.76(d, J = 24.2 Hz), 31.56(d, J = 8.0 Hz). 19FNMR (376 MHz, CDCl3) δ -111.96.HRMS (ESI) m / z calcd. for C8H7FO [M+H]+139.0554, found 139.0557. Example 22 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Is are prepared.

[0107]

[0108] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-chlorostyrene, and the yield of the product is 15%. The structure of the product (the compound shown in Formula Is) is characterized as follows: a colorless oily liquid. 1 HNMR (400 MHz, CDCl3) δ 7.57 (d, J = 7.6 Hz, 1H), 7.42 (q, J = 7.9 Hz, 2H), 7.33 (dd, J = 15.9, 8.9 Hz, 1H), 2.67 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ200.59, 139.18, 132.09, 131.37, 130.72, 129.48, 127.02, 30.80.HRMS (ESI) m / zcalcd. for C8H7 35.5 ClO [M+H]+ 155.0258, found 155.0262. Example 23 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula It are prepared.

[0109]

[0110] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-bromostyrene, and the yield of the product is 58%. The structure of the product (the compound shown in Formula It) is characterized as follows: a pale yellow liquid. 1 HNMR (400 MHz, CDCl3) δ 7.65 (d, J = 7.9 Hz, 1H), 7.50 (d, J = 7.6 Hz, 1H), 7.41 (t, J = 7.5 Hz, 1H), 7.33 (t, J = 7.6 Hz, 1H), 2.67 (s, 3H). 13C NMR (101MHz, CDCl3) δ 201.54, 141.58, 133.97, 131.93, 129.04, 127.57, 119.03,30.47.HRMS (ESI) m / z calcd. for C8H7 79 BrO [M+H]+ 197.0258, found 197.0499. Example 24 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Iu are prepared.

[0111]

[0112] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 5-vinylbenzo[d][1,3]dioxane, and the yield of the product is 58%. The structure of the product (the compound represented by formula Iu) is characterized as follows: a light yellow solid. 1 H NMR (400 MHz, CDCl3) δ 7.58 (d, J = 8.1 Hz, 1H), 7.46 (s,1H), 6.88 (d, J = 8.1 Hz, 1H), 6.07 (s, 2H), 2.57 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.35, 151.88, 148.28, 132.22, 124.88, 108.07, 107.93, 101.97,26.59.HRMS (ESI) m / z calcd. for C9H8O3[M+H]+ 165.0546, found 165.0553. Example 25 This embodiment provides a method for preparing ketone compounds, by which compounds as shown in Formula Iv are prepared.

[0113]

[0114] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-vinylnaphthalene, and the yield of the product is 62%. The structure of the product (the compound shown in Formula Iv) is characterized as follows: white powder. 1H NMR(400 MHz, CDCl3) δ 8.50 (s, 1H), 8.07 (d, J = 8.6 Hz, 1H), 8.00 (d, J = 8.0Hz, 1H), 7.96 – 7.88 (m, 2H), 7.61 (dt, J = 19.8, 6.8 Hz, 2H), 2.76 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 198.24, 135.69, 134.57, 132.61, 130.32, 129.66,128.58, 128.53, 127.89, 126.89, 123.99, 26.81.HRMS (ESI) m / z calcd.forC 12 H 10 O [M+H]+ 171.0804, found 171.0812. Example 26 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Iw are prepared.

[0115]

[0116] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with trans-1,2-diphenylene, and the yield of the product is 48%. The structural characterization of the product (the compound shown in Formula Iw) is as follows: a pale yellow solid. 1 H NMR (400 MHz, CDCl3) δ 8.06 (d, J = 7.9 Hz, 2H), 7.60 (t, J = 7.3 Hz,1H), 7.50 (t, J = 7.6 Hz, 2H), 7.43 – 7.34 (m, 2H), 7.30 (dd, J = 11.0, 7.1Hz, 3H), 4.33 (s, 2H). 13 C NMR (101 MHz, CDCl3) δ 197.79, 136.68, 134.63,133.30, 129.59, 128.79, 128.76, 128.73, 127.01, 45.61.HRMS (ESI) m / z calcd.for C 14 H 12 O [M+H]+ 197.0961, found 197.0970. Example 27 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Ix are prepared.

[0117]

[0118] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with methyl cinnamate, and the yield of the product is 51%. The structure of the product (the compound shown in Formula Ix) is characterized as follows: white solid. 1 H NMR (400 MHz, CDCl3) δ 7.98 (d, J = 7.8 Hz, 2H), 7.64 (t, J = 7.3 Hz, 1H), 7.52 (t, J = 7.2 Hz, 2H), 4.05 (s, 2H), 3.79 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ192.53, 168.10, 133.95, 128.94, 128.64, 126.19, 52.64, 45.83.HRMS (ESI) m / zcalcd. for C 14 H 12 O [M+H]+ 197.0703, found 197.0970. Example 28 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Iy are prepared.

[0119]

[0120] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 2-methyl-1-phenylpropene, and the yield of the product is 46%. The structure of the product (the compound shown in Formula Iy) is characterized as follows: a colorless oily liquid. 1 H NMR (400 MHz, CDCl3) δ 7.99 (d, J = 8.0 Hz, 2H), 7.58 (t, J = 7.0Hz, 1H), 7.50 (t, J = 7.5 Hz, 2H), 3.59 (dt, J = 13.5, 6.8 Hz, 1H), 1.26 (d,J = 1.0 Hz, 3H), 1.24 (d,J = 1.0 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 204.68,136.31, 132.92, 128.73, 128.43, 35.47, 19.27.HRMS (ESI) m / z calcd. for C 10 H 12 O[M+H]+ 149.0961, found 149.0970. Example 29 This embodiment provides a method for preparing ketone compounds, using which compounds as shown in Formula Iz are prepared.

[0121]

[0122] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with indene, and the yield of the product is 26%. The structural characterization of the product (the compound shown in Formula Iz) is as follows: white flaky crystals. 1 H NMR (400 MHz, CDCl3) δ 7.78 (d, J = 7.6 Hz, 1H), 7.61 (t, J = 7.4 Hz, 1H), 7.50 (d, J = 7.7 Hz, 1H), 7.39 (t, J = 7.4 Hz, 1H), 3.22 – 3.12 (m, 2H), 2.75 –2.67 (m, 2H). 13 C NMR (101 MHz, CDCl3) δ 207.21, 155.26, 137.14, 134.69,127.35, 126.79, 123.77, 36.30, 25.88.HRMS (ESI) m / z calcd. for C9H8O [M+H]+133.0648, found 133.0654. Example 30 This embodiment provides a method for preparing ketone compounds, using which compounds of formula I-aa are prepared.

[0123]

[0124] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with 1,2-dihydronaphthalene, and the yield of the product is 41%. The structure of the product (the compound represented by formula I-aa) is characterized as follows: a yellow liquid. 1H NMR (400 MHz, CDCl3) δ 8.05 (d, J = 7.8 Hz, 1H), 7.49 (t, J = 7.5 Hz, 1H), 7.32 (t, J = 7.6 Hz, 1H), 7.27 (d, J = 7.6 Hz, 1H), 2.99 (t, J = 6.1 Hz, 2H), 2.75– 2.59 (m, 2H), 2.28 – 2.05 (m, 2H). 13 C NMR (101 MHz, CDCl3) δ 198.51, 144.57,133.47, 132.65, 128.85, 127.20, 126.68, 39.23, 29.76, 23.34.HRMS (ESI) m / zcalcd. for C 10 H 10 O [M+H]+ 147.0804, found 147.0812. Example 31 This embodiment provides a method for preparing ketone compounds, by which compounds as shown in Formula Ib are prepared.

[0125]

[0126] The preparation steps in this embodiment are basically the same as in Example 3, except that styrene is replaced with allyl phenyl sulfide, and the yield of the product is 53%. The structure of the product (the compound shown in Formula I-ad) is characterized as follows: a light white powder. 1 H NMR (400 MHz, CDCl3) δ 7.40 – 7.29 (m, 4H), 7.25 (t, J = 7.1 Hz, 1H), 3.70 (s, 2H), 2.30 (s, 3H). 13 C NMR (101 MHz, CDCl3) δ 203.65, 134.75, 129.55,129.24, 126.96, 744.71,28.08.HRMS (ESI) m / z calcd. for C9H 10 OS [M+H]+167.0525, found 167.0524. The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing methyl ketones by Wacker-type oxidation, characterized in that, The process includes the following steps: adding a hydrocarbon compound, a palladium catalyst, a ligand, and an oxidant to an alcohol solvent, and then heating the mixture under a protective atmosphere to obtain a methyl ketone compound; The oxidant is an Oxone oxidant; The ligand is 2-phenyl-1H-benzo[d]imidazole.

2. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The hydrocarbon compound is at least one of the following compounds with the following structural formulas: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 3. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The palladium catalyst is at least one of palladium acetate, palladium chloride, palladium trifluoroacetate, palladium acetate hydrate, palladium chloride hydrate, and palladium trifluoroacetate hydrate.

4. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The alcohol solvent is a fatty alcohol; the chemical formula of the fatty alcohol has 1-4 carbon atoms.

5. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The molar amount of the palladium catalyst is 0.5 mol% to 5 mol% of the molar amount of the hydrocarbon compound.

6. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The molar ratio of the ligand to the palladium catalyst is from 1:1 to 5:

1.

7. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The molar amount of the oxidant is 1.0-3.0 times the molar amount of the hydrocarbon compound.

8. The method for preparing methyl ketones by Wacker-type oxidation according to claim 1, characterized in that, The molar volume ratio of the hydrocarbon compound to the alcohol solvent is 0.1-0.5:1 mmol / mL.

9. The method for preparing methyl ketones by Wacker-type oxidation according to any one of claims 1-8, characterized in that, The protective atmosphere is at least one of nitrogen, argon, neon, and helium; the heating treatment temperature is 40-80℃, and the heating treatment time is 2-24 hours.

10. The method for preparing methyl ketones by Wacker-type oxidation according to claim 9, characterized in that, The heat treatment temperature is 50-60℃, and the heat treatment time is 6-12 hours.

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