A catalytic system for deoxygenation of phenol derivatives and a mild and efficient deoxygenation method and application thereof

Abstract

A catalytic system for the deoxygenation of phenolic derivatives, a mild and efficient deoxygenation method and its application. The present invention belongs to the field of deoxygenation of phenolic compounds and preparation of aromatic hydrocarbons. The present invention aims to solve the technical problems of limited applicability of substrate functional groups, high reagent toxicity and high reaction temperature in existing systems and methods. The catalytic system of the present invention comprises a palladium catalyst, a ligand and a reducing agent, wherein the ligand is an electron-rich bisphosphine ligand. The present invention changes the electronic properties and steric hindrance of the metal center by screening the electron-rich bisphosphine ligand, thereby regulating the catalytic activity of the palladium complex, and ultimately provides a mild and efficient deoxygenation method for phenolic derivatives. The method has the advantages of mild reaction conditions, short reaction time, low catalyst dosage, wide substrate applicability, etc., and is conducive to the large-scale production of deoxygenated phenolic derivatives.

Description

Technical Field

[0001] The present invention belongs to the field of deoxygenation of phenolic compounds and preparation of aromatic hydrocarbons, and particularly relates to a catalytic system for deoxygenation of phenolic derivatives and a mild and efficient deoxygenation method and application. Background Art

[0002] Phenolic compounds are widely present in fossil fuels and renewable biomass resources. Compared with halogenated aromatic hydrocarbons, which are commonly used as aromatic raw materials, phenolic compounds are a class of organic synthetic building blocks that are abundant, easy to prepare, and low-cost. The phenolic hydroxyl group can be converted into other useful functional groups through various reactions. Furthermore, the defunctionalization (i.e., deoxygenation reduction) of phenolic compounds is also an important chemical transformation, playing an important role in the synthesis of natural products and pharmaceutically active molecules. For example, the phenolic hydroxyl group is crucial for the expression of physiological activity of many bioactive molecules. Effective deoxygenation methods can provide deoxy analogs, thereby facilitating the study of related structure-activity relationships.

[0003] On the other hand, utilizing biomass as a renewable resource to produce liquid fuels to replace fossil fuels has attracted widespread attention. Bio-oil, a complex mixture obtained by pyrolysis, gasification, and quenching of biomass, contains a large amount of phenolic compounds. The presence of these compounds has significant negative impacts on bio-oil quality, such as low calorific value, poor stability, low volatility, and high viscosity. Therefore, developing new methods to deoxygenate phenolic compounds has become a key area of interest for improving bio-oil quality.

[0004] Phenolic compounds have very high CO bond energy, so it is very difficult to directly deoxygenate them. The most reliable and practical way to achieve the reduction reaction is to introduce suitable electron-withdrawing groups to activate the CO bond. For the deoxygenation reaction of phenolic derivatives, researchers have so far developed some Pd or Ni catalytic systems. The Pd(OAc)2 / dppf / HCOOH / Et3N system can achieve the reduction of the substrate ArOTf at a temperature of 60-90°C. Using i-PrOH as a reducing agent and Pd(OAc)2 / CM-phos as a catalyst, the deoxygenation of ArOTs can be catalyzed at 60-110°C. The reaction temperature of the above two Pd catalytic systems is relatively high. Another technical route for the deoxygenation of phenolic compounds is to first convert phenol into a fluorosulfonate ester and then react with Pd(OAc )2 / dppp / HCOOH / Et3N system. Although this catalytic reaction can be carried out under mild conditions, the phenolic hydroxyl activation reagent used is highly toxic sulfuryl fluoride, which is a gas at normal pressure, making large-scale production impossible. In addition, the catalytic systems Pd / C / Mg / NH4OAc and Pd / C / Et2NH / H2 can catalyze the deoxygenation of ArOTf and ArOMs at room temperature. The reaction involves a single electron transfer process from Mg or Et2NH to the sulfonate aromatic ring activated by Pd coordination. These two methods are not suitable for substrates containing sensitive groups such as carbonyl, nitro, and halogen. Regarding Ni catalysts, the NiBr2(PPh3)2 / Zn / MeOH system can catalyze the deoxygenation reaction of substrates ArOTf and ArOMs at room temperature to 50°C, but it has shortcomings such as the use of metal reducing agents, which makes post-processing inconvenient and the limited applicability of functional groups. Although the NiCl2 / NaBH4 and NiCl2(PPh3)2 / PCy3 / NaBH4 systems can enable the reduction of ArOMs under mild conditions, they require the addition of a large amount of NiCl2 and a large excess of NaBH4. Furthermore, sensitive groups such as formyl and ketone carbonyl groups are not tolerant to NaBH4. Therefore, the development of a mild and efficient deoxygenation method for phenolic derivatives is particularly necessary. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a catalytic system for deoxygenation of phenol derivatives and a mild and efficient deoxygenation method and application.

[0006] The purpose of the present invention is to achieve through the following technical solutions:

[0007] One of the purposes of the present invention is to provide a catalytic system for deoxygenation of phenol derivatives, the catalytic system comprising a palladium catalyst, a ligand and a reducing agent, characterized in that: the ligand is a bisphosphine ligand represented by L1 to L5, wherein R 1 ~R 6 Each is independently selected from electron-rich alkyl, R7=H, Ph or TMS, X=CH2 or O, Y=CH or N, Ar1 is selected from heteroaryl containing N, O or S atoms;

[0008]

[0009] Preferably, the electron-rich alkyl group is selected from a C1-C6 linear, branched or cyclic alkyl group, and the heteroaryl group containing N, O or S atoms includes furyl, thienyl, pyrrolyl, indolyl, carbazolyl, benzofuranyl and benzothienyl.

[0010] More preferably, the electron-rich alkyl group is specifically tert-butyl, isopropyl, cyclohexyl, cyclopentyl, or adamantyl, and the heteroaryl group containing N, O, or S atoms is specifically 2-furyl, 2-thienyl, 2-benzofuranyl, or 2-benzothienyl.

[0011] Most preferably, the bisphosphine ligand specifically includes the structures shown in L1a to L5a, L2b to L3b:

[0012]

[0013] Preferably, the phenol derivative is an aryl sulfonate, expressed as Ar2-OAG, wherein Ar2 is a substituted or unsubstituted aryl or heteroaryl group, and AG is a trifluoromethanesulfonyl group, a p-toluenesulfonyl group, or a methanesulfonyl group.

[0014] More preferably, the substituted aryl group is one or more substituted aryl groups selected from the group consisting of alkyl, biphenyl, alkoxy, cyano, trifluoromethyl, acyl, amide, alkoxycarbonyl, nitro, amino, phenolic hydroxyl, and halogen.

[0015] More preferably, the heteroaryl group is pyridyl, thienyl, furyl, quinolyl, benzothienyl, or benzofuranyl.

[0016] Preferably, the palladium catalyst is one or more of palladium acetate, palladium chloride, palladium bromide, palladium sulfate, palladium nitrate, palladium trifluoroacetate, palladium acetylacetonate, bis(dibenzylideneacetone)palladium, palladium hydroxide, and palladium-carbon.

[0017] More preferably, the palladium catalyst is palladium acetate.

[0018] Preferably, the reducing agent is one or more of trialkylsilane, trialkoxysilane, phenylsilane, diphenylsilane, triphenylsilane, 1,1,3,3-tetramethyldisiloxane, dimethylphenylsilane, tris(trimethylsilyl)silane, polymethylhydrogensiloxane, sodium formate, and formic acid-triethylamine.

[0019] More preferably, the reducing agent is formic acid-triethylamine, triethylsilane or trialkoxysilane.

[0020] Preferably, the molar ratio of the phenol derivative, the palladium catalyst, the ligand, and the reducing agent is 1:(0.005-0.05):(0.01-0.1):(2-6).

[0021] Preferably, the catalytic system further comprises a solvent, and the solvent is selected from one or more of tetrahydrofuran, acetonitrile, methanol, ethanol, isopropanol, toluene, dichloromethane, 1,4-dioxane, ethylene glycol dimethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0022] More preferably, the solvent is tetrahydrofuran or acetonitrile.

[0023] A second object of the present invention is to provide a mild and efficient method for deoxygenating phenolic derivatives, which is carried out according to the following steps:

[0024] In a nitrogen atmosphere, the catalytic system is used to carry out a deoxygenation reduction reaction of phenol derivatives at room temperature.

[0025] Preferably, the room temperature is 20-30° C., and the reaction time is 0.5-10 h.

[0026] A third object of the present invention is to provide a mild and efficient method for deoxygenating phenolic derivatives for use in improving the quality of bio-oil.

[0027] Compared with the prior art, the present invention has the following significant effects:

[0028] The present invention modulates the electronic properties and steric hindrance of the metal center by screening electron-rich bisphosphine ligands, thereby regulating the catalytic activity of the palladium complex. Ultimately, it provides a mild and efficient deoxygenation method for phenol derivatives, which helps to achieve large-scale production of deoxygenated phenol derivatives. The specific advantages are as follows:

[0029] (1) The present invention has mild reaction conditions, convenient post-processing, and high product yield;

[0030] (2) The system of the present invention uses a small amount of catalyst and the reducing agent is cheap and readily available;

[0031] (3) The reaction time of the present invention is short. For most substrates, the reaction can be completed within 1 to 3 hours.

[0032] (4) The substrates of the system of the present invention are widely applicable and can tolerate various functional groups such as nitro, formyl, cyano, and halogen atoms that are easily reduced in other methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the H NMR spectrum of the product obtained in Example 1 of the present invention;

[0034] Figure 2 This is the H NMR spectrum of the product obtained in Example 8 of the present invention;

[0035] Figure 3 This is the NMR carbon spectrum of the product obtained in Example 8 of the present invention;

[0036] Figure 4 This is the H NMR spectrum of the product obtained in Example 12 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.

[0039] Example 1

[0040]

[0041] 2-Naphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L1a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (2 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.117 g of the desired naphthalene in a 91% yield.

[0042] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0043] Example 2

[0044]

[0045] 4-Biphenyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.02 mmol, 2 mol%), and bisphosphine ligand L1a (0.04 mmol, 4 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (2 mmol, 2 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (2 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.145 g of the target biphenyl in a 94% yield.

[0046] 1HNMR (400MHz, CDCl3): δ7.64-7.57(m,4H),7.49-7.41(m,4H),7.39-7.33(m,2H).

[0047] Example 3

[0048]

[0049] 3,4,5-Trimethoxyphenyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.05 mmol, 5 mol%), and bisphosphine ligand L2a (0.06 mmol, 6 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, acetonitrile (3 mL) was added. Triethylamine (4 mmol, 4 equiv) and formic acid (3 mmol, 3 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (2 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.151 g of the target compound, 1,2,3-trimethoxybenzene, in a 90% yield.

[0050] 1 H NMR (500MHz, CDCl3): δ6.98 (t, J=8.0Hz, 1H), 6.58 (d, J=8.0Hz, 2H), 3.85 (s, 6H), 3.84 (s, 3H).

[0051] Example 4

[0052]

[0053] 2-Bromo-4-methoxyphenyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L2a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, acetonitrile (3 mL) was added. Triethylamine (2 mmol, 2 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (1 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.178 g of the target compound, m-bromoanisole, in a 95% yield.

[0054] 1 H NMR (500MHz, CDCl3): δ7.15 (t, J=7.95Hz, 1H), 7.12-7.06 (m, 2H), 6.85 (ddd, J=8.2, 2.5, 1.1Hz, 1H), 3.79 (s, 3H).

[0055] Example 5

[0056]

[0057] 4-Acetylphenyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L3a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, acetonitrile (3 mL) was added. Triethylsilane (2.5 mmol, 2.5 equiv) was added with stirring at 25°C and continued stirring at 25°C. The reaction was monitored by TLC until completion (1 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.103 g of the target acetophenone in an 86% yield.

[0058] 1 H NMR (500MHz, CDCl3): δ7.99-7.91(m,2H),7.58-7.53(m,1H),7.49-7.43(m,2H),2.60(s,3H).

[0059] Example 6

[0060]

[0061] 1-Formylnaphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.02 mmol, 2 mol%), and bisphosphine ligand L3a (0.03 mmol, 3 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (2 mmol, 2 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (1 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.142 g of the target compound, 1-naphthaldehyde, in a yield of 91%.

[0062] 1 H NMR (500MHz, CDCl3): δ10.38(s,1H),9.27(d,J=8.6Hz,1H),8.07(d,J=8.1Hz,1H),7.96( dd,J=7.0,1.4Hz,1H),7.91(dd,J=8.2,1.4Hz,1H),7.68-7.63(m,1H),7.60-7.53(m,2H).

[0063] Example 7

[0064]

[0065] 8-Quinolinyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.02 mmol, 2 mol%), and bisphosphine ligand L3a (0.04 mmol, 4 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Trimethoxysilane (3 mmol, 3 equiv) was added with stirring at 25°C and continued stirring at 25°C. The reaction was monitored by TLC until completion (1 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.112 g of the target quinoline in an 87% yield.

[0066] 1 H NMR (500MHz, CDCl3): δ8.88(dd,J=4.2,1.8Hz,1H),8.15(d,J=8.7Hz,1H),8.11(d,J=8.7Hz,1H) ,7.75(dd,J=8.1,1.4Hz,1H),7.69-7.65(m,1H),7.51-7.48(m,1H),7.32(dd,J=8.3,4.2Hz,1H).

[0067] Example 8

[0068]

[0069] Estrone trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L3a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, acetonitrile (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (2 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.237 g of the target compound, 3-deoxyestrolone, in a yield of 93%.

[0070] 1 H NMR (500MHz, CDCl3): δ7.31 (d, J = 7.7Hz, 1H), 7.20-7.09 (m, 3H), 2.95-2.92 (m, 2H), 2.54-2. 40(m,2H),2.33(td,J=10.8,3.8Hz,1H),2.22-1.93(m,4H),1.72-1.41(m,6H),0.92(s,3H).

[0071] 13 C NMR (126MHz, CDCl3): δ220.9,139.7,136.5,129.0,125.8,125.7,125.3,50.6,48.0,44.5,38.1,35.9,31.6,29.4,26.5,25.7,21.6,13.9.

[0072] Example 9

[0073]

[0074] Trifluoromethanesulfonate (1 mmol), palladium acetate (0.05 mmol, 5 mol%), and bisphosphine ligand L4a (0.08 mmol, 8 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylsilane (6 mmol, 6 equiv) was added with stirring at 25°C and continued stirring at 25°C. The reaction was monitored by TLC until completion (6 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.167 g of the target compound (E)-1,2-stilbene in a 93% yield.

[0075] 1 H NMR (500MHz, CDCl3): δ7.55-7.50(m,4H),7.38-7.34(m,4H),7.29-7.24(m,2H),7.12(s,2H).

[0076] 13 C NMR (126MHz, CDCl3): δ = 137.3, 128.7, 128.6, 127.6, 126.5.

[0077] Example 10

[0078]

[0079] 2-Naphthyl p-toluenesulfonate (1 mmol), palladium acetate (0.02 mmol, 2 mol%), and bisphosphine ligand L4a (0.04 mmol, 4 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, acetonitrile (3 mL) was added. Triethylsilane (2.5 mmol, 2.5 equiv) was added with stirring at 25°C and continued stirring at 25°C. The reaction was monitored by TLC until completion (3 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to yield 0.117 g of the desired naphthalene in a 91% yield.

[0080] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0081] Example 11

[0082]

[0083] 6-cyanonaphthalen-2-yl 4-methylbenzenesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L5a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the atmosphere with nitrogen, acetonitrile (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (3 mmol, 3 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (4 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to afford 0.139 g of the target compound, 2-naphthocarbonitrile, in a 91% yield.

[0084] 1 HNMR (500MHz, CDCl3): δ8.24(s,1H),7.97-7.85(m,3H),7.69-7.58(m,3H).

[0085] Example 12

[0086]

[0087] [6-(Methoxycarbonyl)naphthalen-2-yl] methanesulfonate (1 mmol), palladium acetate (0.05 mmol, 5 mol%), and bisphosphine ligand L5a (0.1 mmol, 10 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethoxysilane (3 mmol, 3 equiv) was added with stirring at 25°C and continued stirring at 25°C. The reaction was monitored by TLC until completion (6 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.174 g of the target compound, methyl 2-naphthoate, in a yield of 93%.

[0088] 1H NMR (500MHz, CDCl3): δ8.62-8.61(m,1H),8.07(dd,J=8.7,1.7Hz,1H),7.96(d,J=8.1Hz,1H),7.89(d,J=8.9Hz,2H),7.62-7.52(m,2H),3,99(s,3H).

[0089] Example 13

[0090]

[0091] 2-Naphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L3a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (1 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.117 g of the desired naphthalene in a 91% yield.

[0092] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0093] Example 14

[0094]

[0095] 2-Naphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L3b (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (10 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.115 g of the desired naphthalene in a 90% yield.

[0096] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0097] Example 15

[0098]

[0099] 2-Naphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L2a (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (3 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.117 g of the desired naphthalene in a 91% yield.

[0100] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0101] Example 16

[0102]

[0103] 2-Naphthyl trifluoromethanesulfonate (1 mmol), palladium acetate (0.01 mmol, 1 mol%), and bisphosphine ligand L2b (0.02 mmol, 2 mol%) were added to a dry reaction tube. After replacing the nitrogen atmosphere, tetrahydrofuran (3 mL) was added. Triethylamine (3 mmol, 3 equiv) and formic acid (2 mmol, 2 equiv) were added with stirring at 25°C. Stirring was continued at 25°C. The reaction was monitored by TLC until completion (2 h). After dilution with saturated brine, the mixture was extracted three times with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and purified by column chromatography to obtain 0.115 g of the desired naphthalene in a 90% yield.

[0104] 1 H NMR (500MHz, CDCl3): δ7.85 (dd, J=6.2, 3.3Hz, 4H), 7.49 (dd, J=6.3, 3.2Hz, 4H).

[0105] Comparative Example

[0106]

[0107] The difference between Comparative Examples 1-10 and Example 1 is that the ligand L used is different, and the ligand L is replaced by any one of the structures shown in L6 to L15. Other parameters and steps are the same as in Example 1.

[0108] The structure of L6 to L15 is as follows:

[0109]

[0110] The results showed that when the ligands were structures shown in L6 to L15, only trace amounts (<5%) to moderate yields of the target compound could be generated at room temperature. Specific results are shown in Table 1.

[0111] Table 1

[0112] Reaction time (h) Yield (%) Comparative Example 1 (L6) 24 35 Comparative Example 2 (L7) 24 trace Comparative Example 3 (L8) 24 trace Comparative Example 4 (L9) 24 trace Comparative Example 5 (L10) 24 trace Comparative Example 6 (L11) 24 trace Comparative Example 7 (L12) 24 trace Comparative Example 8 (L13) 24 55 Comparative Example 9 (L14) 24 65 Comparative Example 10 (L15) 24 60

[0113] The foregoing are merely preferred embodiments of the present invention. These embodiments are all different implementations based on the overall concept of the present invention. The scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A catalytic system for deoxygenation of phenolic derivatives, comprising a palladium catalyst, a ligand and a reducing agent, characterized in that: The ligand is a diphosphine ligand represented by L1, L3~L5, wherein R 1 ~R 6 Each is independently selected from electron-rich alkyl, R7 = H, Ph or TMS, X = CH2 or O, Y = CH or N, Ar1 is selected from heteroaryl containing N, O or S atoms; , the electron-rich alkyl group is specifically tert-butyl, isopropyl, cyclohexyl, cyclopentyl, and the heteroaryl group containing N, O or S atoms is specifically 2-furyl, 2-thienyl, 2-benzofuranyl, 2-benzothienyl.

2. The catalytic system according to claim 1, characterized in that The bisphosphine ligands specifically include the structures shown in L1a, L3a, L3b, L4a, and L5a: 。 3. A catalytic system for deoxygenation of phenolic derivatives, comprising a palladium catalyst, a ligand and a reducing agent, characterized in that: The ligands are diphosphine ligands represented by L2a and L2b: 。 4. The catalytic system according to claim 1 or 3, characterized in that Phenol derivatives are aryl sulfonates, the expression is Ar2-O AG , Ar2 is a substituted or unsubstituted aryl or heteroaryl group, wherein the substituted aryl group is one or more substituted aryl groups selected from alkyl, biphenyl, alkoxy, cyano, trifluoromethyl, acyl, amide, alkoxycarbonyl, nitro, amino, phenolic hydroxyl, and halogen, and the heteroaryl group is pyridyl, thienyl, furyl, quinolyl, benzothienyl, and benzofuranyl. AG The alkyl silane is trifluoromethanesulfonyl, p-toluenesulfonyl, or methylsulfonyl; the palladium catalyst is one or more of palladium acetate, palladium chloride, palladium bromide, palladium sulfate, palladium nitrate, palladium trifluoroacetate, palladium acetylacetonate, bis(dibenzylideneacetone)palladium, palladium hydroxide, and palladium-carbon; and the reducing agent is one or more of trialkylsilane, trialkoxysilane, phenylsilane, diphenylsilane, triphenylsilane, 1,1,3,3-tetramethyldisiloxane, dimethylphenylsilane, tris(trimethylsilyl)silane, polymethylhydrogensiloxane, sodium formate, and formic acid-triethylamine.

5. The catalytic system according to claim 4, characterized in that The reducing agent is formic acid-triethylamine, triethylsilane or trialkoxysilane.

6. The catalytic system according to claim 1 or 3, characterized in that The molar ratio of the phenol derivative, the palladium catalyst, the ligand and the reducing agent is 1:(0.005-0.05):(0.01-0.1):(2-6).

7. A mild and efficient method for deoxygenating phenolic derivatives, characterized in that Follow these steps: In a nitrogen atmosphere, the catalytic system according to any one of claims 1 to 6 is used to carry out a deoxidation reduction reaction on a phenol derivative at room temperature.

8. The method according to claim 7, characterized in that The room temperature is 20~30℃ and the reaction time is 0.5~10 h.

9. Use of the method according to claim 7 or 8 in improving the quality of bio-oil.

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