A method for synthesizing o-aminophenol compounds

Abstract

The present invention relates to a method for synthesizing o-aminophenol compounds, belonging to the technical field of organic synthesis. The present invention uses arylhydroxylamine compounds that are cheap and easy to prepare to react with cheap industrial raw materials sulfonyl chloride and methanol to achieve the rapid and efficient synthesis of o-aminophenol under the condition of no transition metal and oxidant. This strategy has a wide range of substrate scopes and good functional group compatibility, and is of great significance for its further development and application in the fields of functional materials, life and medical sciences, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic chemical synthesis and relates to a method for synthesizing o-aminophenol compounds. Background Art

[0002] 2-Aminophenol widely exists in natural products and drug molecules as an important functional structure. Drugs containing this structure are used as anthelmintics (niclosamide), anti-cancer drugs (destomycin), insecticides (antimycin A3), and bronchodilators for the treatment of asthma and chronic obstructive pulmonary disease (procaterol, formoterol), etc. Due to the important value of 2-aminophenol, various methods for synthesizing o-aminophenol have been developed in recent decades. For example, CN104513169A discloses a method for preparing o-aminophenol, using o-nitrophenol as a raw material and ammonium thiosulfate as a reducing agent to react to prepare o-aminophenol. CN114181098A discloses a method for producing o-aminophenol, mixing and dissolving 60% ethanol and o-nitrophenol, and then catalytic hydrogenation to obtain o-aminophenol. CN114031509A discloses a method for preparing o-aminophenol, using water, nitrobenzene, and sulfuric acid as raw materials, and catalytic hydrogenation to obtain o-aminophenol. However, the existing methods are mainly continuous nitration and reduction of phenol. However, this method usually has disadvantages such as poor regioselectivity, harsh reaction conditions, low yield, and cumbersome reaction process, greatly reducing its production and application value.

[0003] Therefore, it is of great significance to develop a rapid, efficient, highly regioselective and environmentally friendly ortho-hydroxylation strategy for aromatic amines. For this reason, the present invention is proposed. Summary of the Invention

[0004] In view of the above-mentioned status of the prior art, especially the defects of poor regioselectivity, harsh reaction conditions, low yield, and cumbersome reaction process in the existing preparation strategies of o-aminophenol, the inventors of the present invention have conducted in-depth and extensive research on the ortho-hydroxylation of aromatic amines, aiming to achieve the rapid and efficient synthesis of o-aminophenol without transition metals and oxidants. The inventors of the present invention have found that under the condition of no transition metal catalysis, through a tandem rearrangement reaction involving arylhydroxylamine compounds, sulfonyl chloride, and methanol, the efficient and highly regioselective synthesis of ortho-hydroxylated aromatic amine compounds can be achieved. The present invention is precisely based on the foregoing discovery.

[0005] Therefore, the object of the present invention is to provide a method for synthesizing o-aminophenol compounds. Compared with the existing preparation strategy of continuous nitration and reduction of phenol, the present invention realizes the efficient and highly regioselective synthesis of ortho-hydroxylated aromatic amine compounds through a tandem rearrangement reaction involving arylhydroxylamine compounds, sulfonyl chloride, and methanol, without transition metal catalysis and without using oxidants or reducing agents.

[0006] The technical solution for achieving the above object of the present invention can be summarized as follows:

[0007] A method for synthesizing an o-aminophenol compound, which has the structure shown in formula (IV):

[0008]

[0009] In formula (IV), Ar is a substituted or unsubstituted aryl or biaryl, and R is one of benzoyl, acetyl, pivaloyl, ester group, tert-butoxycarbonyl, benzyloxycarbonyl, trifluoroacetyl, 9-fluorenylmethoxycarbonyl;

[0010] It includes the following steps:

[0011] Under an air atmosphere, compound (I) and methanol are added to a solvent, and sulfonyl chloride is added dropwise for reaction. After the reaction is completed, purification is carried out to obtain the target compound (IV);

[0012]

[0013] According to the present invention, preferably, the o-aminophenol compound is a substituted phenyl compound wherein R 1 is one or more of fluorine, chlorine, bromine, iodine, alkyl group, alkynyl group, ester group, alkoxy group, aryl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, oxytrifluoromethyl group, trithiotrifluoromethyl group, silyl group.

[0014] According to the present invention, preferably, the o-aminophenol compound has the following structure:

[0015]

[0016] According to the present invention, during the reaction process, the reaction progress can be tracked by TLC.

[0017] According to the present invention, preferably, the purification method is as follows:

[0018] After the reaction is completed, the reaction mixture is concentrated by a rotary evaporator, and the crude product is subjected to column chromatography. The eluent for column chromatography is petroleum ether:ethyl acetate = 7:1 to obtain the target compound (IV).

[0019] According to the present invention, preferably, the molar ratio of compound (I), compound (II) and compound (III) is 1:(1 - 4):(1 - 4), more preferably 1:(2.5 - 3.5):(2.5 - 3.5); most preferably, the molar ratio of compound (I), compound (II) and compound (III) is 1:3:3.

[0020] According to the present invention, preferably, the solvent is MeCN (acetonitrile), DCM (dichloromethane), DME (ethylene glycol dimethyl ether), CHCl3 (chloroform), EA (ethyl acetate), Et2O (diethyl ether) or THF (tetrahydrofuran);

[0021] Most preferably, the solvent is THF.

[0022] According to the present invention, the compound (I) has the following structure:

[0023]

[0024] The compound (I) can be prepared according to the existing technical route, and the preparation route is as follows:

[0025]

[0026] The synthesis steps are as follows: Under a nitrogen atmosphere, a nitro compound (1.0 equivalent) and 5% Rh / C (0.30 mol% Rh) are dissolved in THF (0.324 M), and then the reaction system is cooled to 0 °C, and hydrazine hydrate (1.2 equivalents) is added dropwise. The reaction mixture is stirred at 0 °C for 1 hour, then slowly warmed to room temperature and stirred at room temperature for 2 hours. After the reaction is completed, the reaction mixture is filtered through diatomaceous earth, concentrated by rotary evaporation, and recrystallized. The obtained crude product hydroxylamine is directly used for the next step.

[0027] To the ethereal solution (0.5 M) of hydroxylamine, saturated aqueous NaHCO3 solution is added, and then the solution is cooled to 0 °C. To the solution, the corresponding acyl chloride (1.1 equivalents) is added. After the addition is completed, the reaction is stirred at 0 °C for 10 seconds, and then quenched with saturated aqueous NH4Cl solution. The reaction mixture is extracted with dichloromethane. The organic layer is washed with saturated brine and dried over anhydrous sodium sulfate. After the solvent is removed under vacuum, the crude product is subjected to column chromatography (the eluent is dichloromethane:ethyl acetate = 50:1) to obtain the compound (I).

[0028] According to the present invention, the o-aminophenol compound has received extensive attention and shown good application prospects in organic synthetic chemistry, material chemistry, pharmaceutical chemistry, chemical biology, etc.

[0029] The technical route of the present invention is as follows:

[0030]

[0031] The reaction mechanism of the present invention is as follows:

[0032]

[0033] First, as a nucleophile, arylhydroxylamine reacts with methyl chlorosulfonate formed in situ from sulfonyl chloride and methanol to generate O-sulfonylated intermediate A. Then, intermediate A undergoes a [3,3]-σ rearrangement to give reactive intermediate B, which then undergoes a re-aromatization process to obtain ortho-sulfonylated intermediate C. Subsequently, intermediate C is hydrolyzed in situ under the action of acid and water, and finally, o-aminophenol compound Ⅳ is formed.

[0034] Advantages of the present invention:

[0035] 1. The present invention provides a strategy for ortho-hydroxylation of arylamines without the participation of transition metals and oxidants. By using inexpensive and easily prepared arylhydroxylamine compounds to react with inexpensive industrial raw materials sulfonyl chloride and methanol, the rapid and efficient synthesis of o-aminophenol is achieved under the conditions without transition metals and oxidants. This strategy has a wide substrate scope and good functional group compatibility, and is of great significance for its further development and application in the fields of functional materials, life and medical sciences.

[0036] 2. The present invention does not require oxidants, reductants and transition metal catalysts, and has simple operation. The target compound can be prepared in high yield at room temperature. The raw materials arylhydroxylamine, sulfonyl chloride and methanol are easy to prepare and obtain. The present invention has good universality, and various arylhydroxylamines, including natural product molecules, can effectively achieve ortho-carbon-hydrogen bond hydroxylation, and o-aminophenol compounds with excellent regioselectivity and diverse structures are prepared in good yields. Description of the drawings

[0037] Figure 1 1H-NMR spectrum of benzyl (2-hydroxyphenyl)carbamate prepared in Example 1; 1 1H-NMR spectrum;

[0038] Figure 2 13C-NMR spectrum of benzyl (2-hydroxyphenyl)carbamate prepared in Example 1; 13 13C-NMR spectrum;

[0039] Figure 3 1H-NMR spectrum of N-(4-chloro-6-hydroxyphenyl)benzamide prepared in Example 2; 1 1H-NMR spectrum;

[0040] Figure 4 13C-NMR spectrum of N-(4-chloro-6-hydroxyphenyl)benzamide prepared in Example 2; 13 13C-NMR spectrum;

[0041] Figure 5 1H-NMR spectrum of N-(2,3-dichloro-6-hydroxyphenyl)benzamide prepared in Example 3; 1 1H-NMR spectrum;

[0042] Figure 61H-NMR spectrum of N-(2,3-dichloro-6-hydroxyphenyl)benzamide prepared in Example 3 13 1H-NMR spectrum;

[0043] Figure 7 1H-NMR spectrum of N-(2-hydroxy-4-((triisopropylsilyl)ethynyl)phenyl)benzamide prepared in Example 4 1 1H-NMR spectrum;

[0044] Figure 8 13C-NMR spectrum of N-(2-hydroxy-4-((triisopropylsilyl)ethynyl)phenyl)benzamide prepared in Example 4 13 13C-NMR spectrum;

[0045] Figure 9 1H-NMR spectrum of 1-hepten-3-yl 4-benzamidino-3-hydroxybenzoate prepared in Example 5 1 1H-NMR spectrum;

[0046] Figure 10 13C-NMR spectrum of 1-hepten-3-yl 4-benzamidino-3-hydroxybenzoate prepared in Example 5 13 13C-NMR spectrum; Detailed implementation mode

[0047] The object of the present invention is to provide a synthesis method of an o-aminophenol compound, and the o-aminophenol compound has the structure shown in formula (IV):

[0048]

[0049] In formula (IV), Ar is a substituted or unsubstituted aryl or biaryl, and R is one of benzoyl, acetyl, pivaloyl, ester group, tert-butoxycarbonyl, benzyloxycarbonyl, trifluoroacetyl, 9-fluorenylmethoxycarbonyl;

[0050] The steps are as follows:

[0051] In an air atmosphere, compound (I) and methanol are added to a solvent, and sulfonyl chloride is added dropwise for reaction. After the reaction is completed, purification is carried out to obtain the target compound (IV);

[0052]

[0053] According to the present invention, in the following examples, the compound (I) has the following structure:

[0054]

[0055] Compound (I) is prepared according to the existing technical route, and the preparation route is as follows:

[0056]

[0057] The synthesis steps are as follows: Under a nitrogen atmosphere, the nitro compound (1.0 equivalent) and 5% Rh / C (0.30 mol% Rh) are dissolved in THF (0.324 M), and then the reaction system is cooled to 0 °C, and hydrazine hydrate (1.2 equivalents) is added dropwise. The reaction mixture is stirred at 0 °C for 1 hour, then slowly warmed to room temperature and stirred at room temperature for 2 hours. After the reaction is completed, the reaction mixture is filtered through diatomaceous earth, concentrated by rotary evaporation, and recrystallized. The obtained crude product hydroxylamine is directly used for the next step.

[0058] To the ethereal solution (0.5 M) of hydroxylamine, saturated aqueous NaHCO3 solution is added, and then the solution is cooled to 0 °C. To the solution, the corresponding acyl chloride (1.1 equivalents) is added. After the addition is complete, the reaction is quenched with saturated aqueous NH4Cl solution after stirring at 0 °C for 10 seconds. The reaction mixture is extracted with dichloromethane. The organic layer is washed with saturated brine and dried over anhydrous sodium sulfate. After the solvent is removed under vacuum, the crude product is subjected to column chromatography (the eluent is dichloromethane:ethyl acetate = 50:1) to obtain compound (I).

[0059] In one or more embodiments, the o-aminophenol compound is a substituted phenyl compound wherein R 1 is one or more of fluorine, chlorine, bromine, iodine, alkyl, alkynyl, ester group, alkoxy group, aryl group, fluoromethyl, difluoromethyl, trifluoromethyl, oxytrifluoromethyl, sulfotrifluoromethyl, and silyl.

[0060] In one or more embodiments, the o-aminophenol compound has the following structure:

[0061]

[0062] In one or more embodiments, during the reaction process, the reaction progress is monitored by TLC.

[0063] In one or more embodiments, the purification method is as follows:

[0064] After the reaction is completed, the reaction mixture is concentrated by a rotary evaporator, and the crude product is subjected to column chromatography. The eluent for column chromatography is petroleum ether:ethyl acetate = 7:1, and the target compound (IV) is obtained.

[0065] According to the present invention, the ratios of the raw materials have an important influence on the yield of the target compound (IV). Therefore, in one or more embodiments, the molar ratio of compound (I), compound (II) and compound (III) is 1:(1 - 4):(1 - 4), more preferably 1:(2.5 - 3.5):(2.5 - 3.5); most preferably, the molar ratio of compound (I), compound (II) and compound (III) is 1:3:3.

[0066] According to the present invention, the reaction solvent and reaction temperature have an important influence on the yield of the target compound (IV). Therefore, in one or more embodiments, the solvent is MeCN (acetonitrile), DCM (dichloromethane), DME (ethylene glycol dimethyl ether), CHCl3 (chloroform), EA (ethyl acetate), Et2O (diethyl ether) or THF (tetrahydrofuran); most preferably, the solvent is THF.

[0067] The present invention will be further illustrated by specific examples below, but not limited thereto.

[0068] Example 1: Benzyl (2 - hydroxyphenyl) carbamate

[0069]

[0070] In a 20 mL reaction tube, benzyl N - hydroxy - N - phenylcarbamate (0.2 mmol, 49 mg) and tetrahydrofuran (2 mL) were added, then methanol (0.6 mmol) was added. While stirring at room temperature, sulfonyl chloride (0.6 mmol) was added dropwise. After the addition was completed, the mixture was stirred for two hours. The reaction progress was monitored by TLC. After the reaction was completed, the reaction mixture was concentrated by rotary evaporation to remove the solvent. The crude product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 7:1) to obtain benzyl (2 - hydroxyphenyl) carbamate as a white powder, with a yield of 49%.

[0071] 1 1H NMR (500 MHz, DMSO - d6): δ 9.67 (s, 1H), 8.38 (s, 1H), 7.56 (d, J = 8.0 Hz, 1H), 7.44–7.41 (m, 2H), 7.41–7.36 (m, 2H), 7.33 (t, J = 7.1 Hz, 1H), 6.92 (td, J = 7.6, 1.7 Hz, 1H), 6.84 (dd, J = 8.0, 1.5 Hz, 1H), 6.76 (td, J = 7.6, 1.5 Hz, 1H), 5.14 (s, 2H).

[0072] 1313C NMR (126 MHz, DMSO-d6): δ 153.76, 136.75, 128.36, 127.87, 127.80, 125.79, 118.96, 115.30, 65.73。

[0073] Example 2, N-(4-chloro-6-hydroxyphenyl)benzamide

[0074]

[0075] In a 20 mL reaction tube, N-(4-chlorophenyl)-N-hydroxybenzamide (0.2 mmol, 50 mg) and tetrahydrofuran (2 mL) were added, then methanol (0.6 mmol) was added. While stirring at room temperature, sulfuryl chloride (0.6 mmol) was added dropwise. After the addition was completed, the mixture was stirred for two hours. The reaction progress was monitored by TLC. After the reaction was completed, the reaction mixture was concentrated by rotary evaporation to remove the solvent. The crude product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 7:1) to obtain pure N-(2,3-dichloro-6-hydroxyphenyl)benzamide as a white powder, with a yield of 83%.

[0076] 1 1H NMR (500 MHz, DMSO-d6): δ 10.14 (s, 1H), 9.87 (s, 1H), 8.00 (d, J = 7.4 Hz, 2H), 7.60 (t, J = 7.3 Hz, 1H), 7.52 (t, J = 7.5 Hz, 2H), 7.41 (d, J = 8.9 Hz, 1H), 6.93 (d, J = 8.9 Hz, 1H).

[0077] 13 13C NMR (126 MHz, DMSO-d6): δ 165.33, 154.18, 133.84, 131.66, 131.54, 128.63, 128.33, 127.77, 124.82, 120.87, 115.58.

[0078] Example 3, N-(2,3-dichloro-6-hydroxyphenyl)benzamide

[0079]

[0080] In a 20 mL reaction tube, N-(2,3-dichlorophenyl)-N-hydroxybenzamide (0.2 mmol, 56 mg) and tetrahydrofuran (2 mL) were added, then methanol (0.6 mmol) was added. While stirring at room temperature, sulfuryl chloride (0.6 mmol) was added dropwise. After the addition was complete, the mixture was stirred for two hours. The reaction progress was monitored by TLC. After the reaction was completed, the reaction mixture was concentrated by rotary evaporation to remove the solvent. The crude product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 7:1) to obtain the pure product N-(2,3-dichloro-6-hydroxyphenyl)benzamide as a white powder, with a yield of 46%.

[0081] 1 1H NMR (500 MHz, DMSO-d6): δ 10.33 (s, 1H), 9.53 (s, 1H), 7.97 (d, J = 7.2 Hz, 2H), 7.69 (d, J = 8.5 Hz, 1H), 7.60 (t, J = 7.3 Hz, 1H), 7.53 (t, J = 7.5 Hz, 2H), 6.96 (d, J = 2.4 Hz, 1H), 6.89 (dd, J = 8.5, 2.4 Hz, 1H).

[0082] 13 13C NMR (126 MHz, DMSO-d6): δ 165.29, 150.69, 134.22, 131.78, 129.09, 128.54, 127.59, 125.66, 125.05, 118.78, 115.56.

[0083] Example 4, N-(2-hydroxy-4-((triisopropylsilyl)ethynyl)phenyl)benzamide

[0084]

[0085] In a 20 mL reaction tube, N-(4-((triisopropylsilyl)ethynyl)phenyl)-N-hydroxybenzamide (0.2 mmol, 79 mg) and tetrahydrofuran (2 mL) were added, then methanol (0.6 mmol) was added. While stirring at room temperature, sulfuryl chloride (0.6 mmol) was added dropwise. After the addition was complete, the mixture was stirred for two hours. The reaction progress was monitored by TLC. After the reaction was completed, the reaction mixture was concentrated by rotary evaporation to remove the solvent. The crude product was purified by column chromatography (eluent: petroleum ether: ethyl acetate = 7:1) to obtain the pure product N-(2-hydroxy-4-((triisopropylsilyl)ethynyl)phenyl)benzamide as a white powder, with a yield of 89%.

[0086] 11H NMR (500 MHz, DMSO-d6): δ 10.20 (s, 1H), 9.48 (s, 1H), 7.97 (d, J = 7.3 Hz, 2H), 7.86 (d, J = 8.2 Hz, 1H), 7.60 (t, J = 7.3 Hz, 1H), 7.53 (t, J = 7.5 Hz, 2H), 7.01 (d, J = 1.8 Hz, 1H), 6.97 (dd, J = 8.2, 1.9 Hz, 1H), 1.09 (s, 21H).

[0087] 13 13C NMR (126 MHz, DMSO-d6): δ 165.07, 148.49, 134.22, 131.82, 128.57, 127.50, 127.26, 123.14, 122.90, 118.73, 118.41, 107.39, 88.76, 18.51, 10.77.

[0088] Example 5, 1-Hepten-3-yl 4-benzamidino-3-hydroxybenzoate

[0089]

[0090] In a 20 mL reaction tube, oct-1-en-3-yl 4-(N-hydroxybenzamidino)benzoate (0.2 mmol, 74 mg) and tetrahydrofuran (2 mL) were added, then methanol (0.6 mmol) was added. While stirring at room temperature, sulfonyl chloride (0.6 mmol) was added dropwise. After the addition was complete, the mixture was stirred for two hours. The reaction progress was monitored by TLC. After the reaction was completed, the reaction mixture was concentrated by rotary evaporation to remove the solvent. The crude product was purified by column chromatography (eluent: petroleum ether:ethyl acetate = 7:1) to obtain 1-hepten-3-yl 4-benzamidino-3-hydroxybenzoate as a white powder, with a yield of 61%.

[0091] 11H NMR (500 MHz, DMSO-d6): δ 10.41 (s, 1H), 9.48 (s, 1H), 8.06 (d, J = 8.3 Hz, 1H), 7.97 (d, J = 7.0 Hz, 2H), 7.62 (t, J = 7.4 Hz, 1H), 7.57–7.53 (m, 3H), 7.50 (dd, J = 8.3, 2.0 Hz, 1H), 5.98–5.90 (m, 1H), 5.43–5.37 (m, 1H), 5.27 (dt, J = 17.3, 1.5 Hz, 1H), 5.20 (dt, J = 10.6, 1.4 Hz, 1H), 1.75–1.67 (m, 2H), 1.39–1.31 (m, 2H), 1.30–1.26 (m, 4H), 0.87–0.82 (m, 3H).

[0092] 13 13C NMR (126 MHz, DMSO-d6): δ 165.13, 164.63, 148.12, 136.89, 134.13, 131.94, 130.82, 128.62, 127.46, 126.01, 122.13, 120.55, 116.16, 115.64, 74.43, 33.56, 30.92, 24.19, 21.93, 13.81.

[0093] Test Example 1

[0094] Using N-hydroxy-N-phenylbenzamide, methanol and sulfonyl chloride as raw materials, with the ratio of N-hydroxy-N-phenylbenzamide, methanol and sulfonyl chloride being 1:3:3, the amount of solvent being 2 mL, the reaction temperature being 25 °C, and reacting for 2 h under an air atmosphere, the effects of temperature and solvent type on the reaction were investigated, as shown in Table 1.

[0095] Table 1 Effects of Temperature and Solvent on the Reaction

[0096]

[0097] From the experimental results in Table 1, it can be seen that THF is the optimal solvent for this reaction and 25 °C at room temperature is the optimal temperature.

[0098] Test Example 2

[0099] Using N-hydroxy-N-phenylbenzamide, methanol and sulfonyl chloride as raw materials, with the amount of solvent being 2 mL, the reaction temperature being 25 °C, and reacting for 2 h under an air atmosphere, the effects of the ratio of N-hydroxy-N-phenylbenzamide, methanol and sulfonyl chloride on the reaction were investigated, as shown in Table 1.

[0100] Table 2 Effects of the Ratio of N-hydroxy-N-phenylbenzamide, Methanol and Sulfonyl Chloride on the Reaction

[0101]

[0102] It can be seen from the experimental results in Table 2 that the ratio of N-hydroxy-N-phenylbenzamide, methanol and sulfonyl chloride at 1:3:3 is the optimal ratio for this reaction.

Claims

1. A method for synthesizing an o-aminophenol compound, the o-aminophenol compound having the structure shown in formula (IV): ； Formula (IV) is a compound with the following structure: ； R is one of benzoyl, acetyl, pivaloyl, ester group, tert-butoxycarbonyl, benzyloxycarbonyl, trifluoroacetyl, 9-fluorenylmethoxycarbonyl; The method comprises the following steps: Under an air atmosphere, compound (I) and methanol are added to a solvent, and sulfonyl chloride is added dropwise for reaction. After the reaction is completed, purification is carried out to obtain the target compound (IV); 。 2. The synthesis method of the o-aminophenol compound according to claim 1, wherein The purification method is as follows: After the reaction is completed, the reaction mixture is concentrated by a rotary evaporator, and the crude product is subjected to column chromatography. The eluent for column chromatography is petroleum ether: ethyl acetate = 7:1 to obtain the target compound (IV).

3. The synthesis method of the o-aminophenol compound according to claim 1, wherein The molar ratio of compound (I), compound (II) and compound (III) is 1:(1 - 4):(1 - 4).

4. The synthesis method of the o-aminophenol compound according to claim 1, wherein The molar ratio of compound (I), compound (II) and compound (III) is 1:(2.5 - 3.5):(2.5 - 3.5).

5. The synthesis method of the o-aminophenol compound according to claim 1, characterized in that, The solvent is MeCN, DCM, DME, CHCl3, EA, Et2O or THF.

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