CN117342931B - A method for preparing 5-alkylresorcinol compounds - Google Patents
A method for preparing 5-alkylresorcinol compoundsInfo
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- CN117342931B CN117342931B CN202210734889.0A CN202210734889A CN117342931B CN 117342931 B CN117342931 B CN 117342931B CN 202210734889 A CN202210734889 A CN 202210734889A CN 117342931 B CN117342931 B CN 117342931B
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/06—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by conversion of non-aromatic six-membered rings or of such rings formed in situ into aromatic six-membered rings, e.g. by dehydrogenation
- C07C37/07—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by conversion of non-aromatic six-membered rings or of such rings formed in situ into aromatic six-membered rings, e.g. by dehydrogenation with simultaneous reduction of C=O group in that ring
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
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Abstract
The invention relates to a preparation method of a 5-alkyl resorcinol compound. Specifically, the method comprises the following steps of carrying out dehydroaromatization reaction on the compound shown in the formula (2) under the action of a catalyst and persulfate to obtain the 5-alkyl resorcinol compound shown in the formula (1).
Description
Technical Field
The invention belongs to the field of chemical synthesis, and particularly relates to a preparation method of a 5-alkyl resorcinol compound.
Background
The 5-alkyl resorcinol compounds are medical intermediates with higher activity and wide application. The 5-methyl resorcinol can be used for synthesizing the Blastamycin and the grifolin with the anti-tumor invasion activity, and can also be used for detecting antimony, chromium, nitrate and nitrite, pentose, lignin, sugar gum, aldose, beet sugar, sucrose, amylase and the like, and the 5-amyl resorcinol can be used for synthesizing cannabidiol compounds. The structural formula of the 5-amyl resorcinol is shown in the following formula (3):
the current routes for synthesizing the compounds of formula (3) are mainly as follows:
route one
The aldehyde reagent sequentially undergoes a Witting reaction, a Michael addition reaction and a Crisen condensation reaction to obtain a sodium salt intermediate, and reacts with cuprous bromide to obtain a brominated product. The 5-amylresorcinol is then obtained by debromination and decarboxylation in a final yield of about 50% (J.org.chem.1972, 37,18). The routing reagents used in this route are expensive, making this route costly. In addition, the bromination reaction in this route produces polybrominated substituents, which makes it difficult to obtain high purity products that meet market demands.
Route two
The alpha, beta-unsaturated ketone reagent is subjected to Michael addition and Criessen condensation to obtain an alpha, beta-unsaturated cyclohexanone intermediate, and then subjected to aromatization and decarboxylation under the action of bromine and DMF in one pot to obtain 5-amyl resorcinol (J.org.chem., 1977,42,21). This route also produces polybrominated substituents when brominated with equivalent amounts of bromine, resulting in purification difficulties and difficulty in obtaining a high purity product meeting market demand.
Route three
The Bn-protected 3, 5-dihydroxybenzaldehyde is subjected to Witting reaction, debenzylation and reductive hydrogenation to give 5-pentylborcinol (Journal of CHEMICAL RESEARCH 2009,183). This route has a problem in that the raw materials are not commercially available and are not suitable as starting materials for the industrial production of 5-amylresorcinol.
Route four
The bromo-methyl protected resorcinol compound is subjected to coupling reaction, reductive hydrogenation and demethylation in sequence to give 5-amyl resorcinol (European Journal of MEDICINAL CHEMISTRY 2020,204,112620). The route utilizes an expensive metal palladium catalyst and a large amount of boron tribromide, which is not beneficial to industrial production.
In summary, the existing synthesis method has many disadvantages, such as low total yield, high cost, many byproducts, difficult purification, many wastes, and the like, and is not suitable for industrial production.
Disclosure of Invention
Technical problem
The invention aims to provide a synthesis method of 5-alkyl resorcinol compounds, which reduces the catalyst consumption, reduces the generation of reaction waste, improves the total yield of target products, and is suitable for industrial mass production.
Technical proposal
In one aspect, the present application provides a method for preparing a 5-alkylresorcinol compound represented by formula (1), comprising the steps of:
Under the action of a catalyst and persulfate, carrying out dehydroaromatization reaction on the compound shown in the formula (2) to obtain the 5-alkyl resorcinol compound shown in the formula (1):
Wherein in formulas (1) and (2), R 1 is selected from C 1～C10 straight-chain or branched-chain alkyl, R 2 is selected from hydrogen, -CO 2 R, wherein R is selected from one of C 1～C10 straight-chain or branched-chain alkyl, substituted or unsubstituted benzyl and substituted or unsubstituted C 6～C10 aryl, and the substituent in the substituted benzyl or the substituted aryl can be one or more and can be selected from methoxy and halogen;
wherein the catalyst can be one or more than two of iodine, potassium iodide, sodium iodide, bromine, potassium bromide and sodium bromide.
In specific embodiments, in formula (1) and formula (2), R 1 is one selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl.
In particular embodiments, in formula (1) and formula (2), R 2 is hydrogen or-CO 2 R, wherein R is selected from one of C 1～C10 straight or branched chain alkyl, substituted or unsubstituted benzyl, substituted or unsubstituted phenyl, and substituted or unsubstituted naphthyl, the substituted benzyl may be selected from p-methoxybenzyl, 2, 4-dimethoxybenzyl, and monochlorobenzyl, the substituted phenyl may be selected from phenyl substituted with methoxy or halogen, and the substituted naphthyl may be selected from naphthyl substituted with methoxy or halogen, in particular R 2 is hydrogen or-CO 2 R, wherein R is one selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl.
In a specific embodiment, the persulfate may be selected from one or a mixture of two or more of sodium persulfate, potassium persulfate, and ammonium persulfate.
In specific embodiments, the molar ratio of the catalyst to the compound of formula (2) may be 1:20 to 1:2.5, preferably 1:20 to 1:5, for example 1:15 to 1:5 or 1:10 to 1:5.
In specific embodiments, the molar ratio of the persulfate to the compound of formula (2) may be 0.9:1 to 2.0:1, preferably 1:1 to 1.5:1.
In particular embodiments, the dehydroaromatization reaction is carried out in the presence of a solvent, and the solvent may be selected from one or more of water, methylene chloride, dichloroethane, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, toluene, xylene, chlorobenzene, acetonitrile, benzonitrile, t-butanol, N-hexane, N-heptane, cyclohexane.
In a specific embodiment, the reaction temperature of the dehydroaromatization reaction may be 20 to 120 ℃, preferably 30 to 90 ℃.
In a specific embodiment, the reaction time of the dehydroaromatization reaction may be 3 to 24 hours, preferably 6 to 12 hours.
According to the invention, the halogen includes fluorine, chlorine, bromine, iodine.
Advantageous effects
The invention is characterized in that the method uses cheap and easily available raw materials, and has the advantages of direct oxidation and aromatization under the action of an oxidant and a catalyst, low price and mild reaction conditions. The preparation method of the 5-alkyl resorcinol compound designed by the invention is suitable for industrial production of 5-alkyl resorcinol, and can well meet the market demand for 5-alkyl resorcinol compounds.
The invention uses the easily available chemicals as the initial raw materials to prepare the 5-alkyl resorcinol compounds, has the advantages of easily available raw materials, less byproducts, easy purification and higher total yield in the synthesis process, and is suitable for being developed into an industrial production process.
Detailed Description
The advantages of the present invention will now be further described by the following examples, which are to be understood as being for illustrative purposes only and not limiting the scope of the present invention, as obvious variations and modifications thereof by persons skilled in the art are intended to be included within the scope of the present invention.
Unless specifically indicated otherwise, the starting materials, reagents, methods, and the like used in the present invention are those conventionally or known in the art.
EXAMPLE 1 preparation of 2, 4-dihydroxy-6-methylbenzoic acid methyl ester
Methyl 2-hydroxy-4-oxo-6-methylcyclohex-2-ene-1-carboxylate (1.84 g,1.0 eq) and potassium iodide (332 mg,0.2 eq) were placed in a 50mL reaction flask, acetonitrile (10 mL) was added, potassium persulfate (3.24 g,1.2 eq) was added, stirred at 80℃for 12 hours, the solid was removed by filtration, the whole solvent was removed by concentration under reduced pressure, and column chromatography (petroleum ether, ethyl acetate (100:1-10:1)) was carried out to give methyl 2, 4-dihydroxy-6-methylbenzoate (1.31 g, yield 72％).1H NMR(500MHz,CDCl3):δ11.73(s,1H),6.29(d,J＝2.5Hz,1H),6.24(t,J＝2.5Hz,1H),5.57(s,1H),3.93(s,3H),2.50(s,3H).ESI m/z:(M+H)+183.1.
EXAMPLE 2 preparation of 2, 4-dihydroxy-6-methylbenzoic acid methyl ester
2-Hydroxy-4-oxo-6-methylcyclohex-2-ene-1-carboxylic acid methyl ester (1.84 g,1.0 eq) was placed in a 50mL reaction flask, acetonitrile (10 mL) and elemental iodine (255 mg,0.1 eq) were added, followed by potassium persulfate (3.24 g,1.2 eq) and stirring at 70℃for 12 hours, the solids were removed by filtration, the total solvent was removed by concentration under reduced pressure, and column chromatography to give methyl 2, 4-dihydroxy-6-methylbenzoate (1.53 g, yield) 84％).1H NMR(500MHz,CDCl3):δ11.73(s,1H),6.29(d,J＝2.5Hz,1H),6.24(t,J＝2.5Hz,1H),5.57(s,1H),3.93(s,3H),2.50(s,3H).ESI m/z:(M+H)+183.1.
EXAMPLE 3 preparation of methyl 2, 4-dihydroxy-6-n-pentylbenzoate
2-Hydroxy-4-oxo-6-pentylcyclohex-2-ene-1-carboxylic acid methyl ester (2.4 g,1.0 eq) and potassium iodide (332 mg,0.2 eq) were placed in a 50mL reaction flask, acetonitrile (10 mL) was added, potassium persulfate (3.24 g,1.2 eq) was added, stirred at 70℃for 6 hours, the solid was removed by filtration, the whole solvent was removed by concentration under reduced pressure, and column chromatography was performed to give methyl 2, 4-dihydroxy-6-pentylbenzoate (1.42 g, yield) 60％).1H NMR(400MHz,CDCl3):δ0.9(s,3H),1.2-1.7(b,6H),2.8(m,2H),4.0(s,3H),6.2(s,2H).ESI m/z:(M+H)+238.1.
EXAMPLE 4 preparation of methyl 2, 4-dihydroxy-6-n-pentylbenzoate
Methyl 2-hydroxy-4-oxo-6-pentylcyclohex-2-ene-1-carboxylate (1.9 g,1.0 eq) and potassium iodide (270 mg,0.2 eq) were placed in a 50mL reaction flask, toluene (10 mL) was added, followed by potassium persulfate (2.6 g,1.2 eq) and stirred at 80℃for 12 hours, the solids were removed by filtration, the total solvent was removed by concentration under reduced pressure, and column chromatography to give methyl 2, 4-dihydroxy-6-pentylbenzoate (833 g, yield) 60％).1H NMR(400MHz,CDCl3):δ0.9(s,3H),1.2-1.7(b,6H),2.8(m,2H),4.0(s,3H),6.2(s,2H).ESI m/z:(M+H)+238.1.
EXAMPLE 5 preparation of 2, 4-dihydroxy-6-n-pentylbenzoic acid methyl ester
2-Hydroxy-4-oxo-6-pentylcyclohex-2-ene-1-carboxylic acid methyl ester (2.4 g,1.0 eq) was placed in a 50mL reaction flask, acetonitrile (10 mL) and elemental iodine (255 mg,0.1 eq) were added, followed by potassium persulfate (3.24 g,1.2 eq) and stirring at 60℃for 6 hours, the solids were removed by filtration, the total solvent was removed by concentration under reduced pressure, and column chromatography to give methyl 2, 4-dihydroxy-6-pentylbenzoate (1.90 g, yield) 80％).1H NMR(400MHz,CDCl3):δ0.9(s,3H),1.2-1.7(b,6H),2.8(m,2H),4.0(s,3H),6.2(s,2H).ESI m/z:(M+H)+238.1.
EXAMPLE 6 preparation of ethyl 2, 4-dihydroxy-6-n-pentylbenzoate
Ethyl 2-hydroxy-4-oxo-6-pentylcyclohex-2-ene-1-carboxylate (2.54 g,1.0 eq) was taken in a 50mL reaction flask, acetonitrile (10 mL) and elemental iodine (255 mg,0.1 eq) were added, followed by potassium persulfate (3.24 g,1.2 eq) and stirring at 80℃for 12 hours, the solid was removed by filtration, the whole solvent was removed by concentration under reduced pressure, and column chromatography was performed to give ethyl 2, 4-dihydroxy-6-pentylbenzoate (2.06 g, yield 82%). ESI M/z (M+H) + 255.3.
EXAMPLE 7 preparation of methyl 2, 4-dihydroxy-6-n-pentylbenzoate
Methyl 2-hydroxy-4-oxo-6-pentylcyclohex-2-ene-1-carboxylate (2.4 g,1.0 eq) was placed in a 50mL reaction flask, acetonitrile (10 mL) and bromine (160 mg,0.1 eq) were added, sodium persulfate (2.85 g,1.2 eq) was added, stirred at 80℃for 12 hours, the solids were removed by filtration, the total solvent was removed by concentration under reduced pressure, and column chromatography was performed to give methyl 2, 4-dihydroxy-6-pentylbenzoate (1.55 g, yield) 65％).1H NMR(400MHz,CDCl3):δ0.9(s,3H),1.2-1.7(b,6H),2.8(m,2H),4.0(s,3H),6.2(s,2H).ESI m/z:(M+H)+238.1.
EXAMPLE 8 preparation of methyl 2, 4-dihydroxy-6-n-pentylbenzoate
2-Hydroxy-4-oxo-6-n-pentylcyclohex-2-ene-1-carboxylic acid methyl ester (2.4 g,1.0 eq) was placed in a 50mL reaction flask, acetonitrile (10 mL) and potassium bromide (238 mg,0.2 eq) were added, sodium persulfate (2.85 g,1.2 eq) was added, stirred at 90℃for 6 hours, the solid was removed by filtration, the whole solvent was removed by concentration under reduced pressure, and column chromatography was performed to give methyl 2, 4-dihydroxy-6-n-pentylbenzoate (1.38 g, yield) 58％).1H NMR(400MHz,CDCl3):δ0.9(s,3H),1.2-1.7(b,6H),2.8(m,2H),4.0(s,3H),6.2(s,2H).ESI m/z:(M+H)+238.1.
EXAMPLE 9 preparation of 5-n-pentyl-1, 3-benzenediol
Placing 3-hydroxy-5-n-pentylcyclohex-2-en-1-one (1.82 g,1.0 eq) in a 50mL reaction flask, adding acetonitrile (10 mL) and bromine (160 mg,0.1 eq), further adding sodium persulfate (2.85 g,1.2 eq), stirring at 80deg.C for 12 hours, filtering to remove solids, concentrating under reduced pressure to remove all solvent, and performing column chromatography to obtain 5-n-pentyl-1, 3-benzenediol (0.87 g, yield) 70％).1H NMR(400MHz,CDCl3):δ6.26(t,J＝2.2Hz,1H),6.19(t,J＝2.2Hz,1H),2.50-2.38(m,2H),1.36-1.21(m,4H),0.87(q,J＝6.6Hz,3H).ESI m/z:(M+H)+181.2.
EXAMPLE 10 preparation of 5-n-pentyl-1, 3-benzenediol
Placing 3-hydroxy-5-n-pentylcyclohex-2-en-1-one (1.82 g,1.0 eq) in a 50mL reaction flask, adding acetonitrile (10 mL) and elemental iodine (255 mg,0.1 eq), adding sodium persulfate (2.85 g,1.2 eq), stirring at 80deg.C for 12 hours, filtering to remove solids, concentrating under reduced pressure to remove all solvent, and performing column chromatography to obtain 5-n-pentyl-1, 3-benzenediol (1.53 g, yield) 85％).1H NMR(400MHz,CDCl3):δ6.26(t,J＝2.2Hz,1H),6.19(t,J＝2.2Hz,1H),2.50-2.38(m,2H),1.36-1.21(m,4H),0.87(q,J＝6.6Hz,3H).ESI m/z:(M+H)+181.2.
Claims (12)
1. A preparation method of 5-alkyl resorcinol compounds comprises the following steps:
Under the action of a catalyst and persulfate, carrying out dehydroaromatization reaction on the compound shown in the formula (2) to obtain the 5-alkyl resorcinol compound shown in the formula (1):
Wherein in the formulas (1) and (2),
R 1 is selected from C 1～C10 straight or branched alkyl;
R 2 is selected from hydrogen, -CO 2 R, wherein R is selected from one of C 1～C10 linear or branched alkyl, substituted or unsubstituted benzyl, substituted or unsubstituted C 6～C10 aryl, and the substituent in the substituted benzyl or substituted aryl can be one or more and is selected from methoxy and halogen;
Wherein the catalyst is selected from one or more than two of iodine, potassium iodide, sodium iodide, bromine, potassium bromide and sodium bromide, the molar ratio of the catalyst to the compound of the formula (2) is 1:20-1:2.5,
Wherein the persulfate is one or more than two selected from sodium persulfate, potassium persulfate and ammonium persulfate, and the molar ratio of the persulfate to the compound of the formula (2) is 0.9:1-2.0:1.
2. The method according to claim 1, wherein in the formula (1) and the formula (2), R 1 is one selected from methyl, ethyl, n-propyl, n-butyl, or n-pentyl.
3. The process according to claim 1, wherein in formula (1) and formula (2), R 2 is hydrogen or-CO 2 R, wherein R is selected from the group consisting of C 1～C10 straight or branched alkyl, substituted or unsubstituted benzyl, substituted or unsubstituted phenyl and substituted or unsubstituted naphthyl,
Wherein the substituted benzyl is selected from the group consisting of p-methoxybenzyl, 2, 4-dimethoxybenzyl, and monochlorobenzyl, the substituted phenyl is selected from the group consisting of phenyl substituted with methoxy or halogen, and the substituted naphthyl is selected from the group consisting of naphthyl substituted with methoxy or halogen.
4. The method according to claim 1, wherein in the formula (1) and the formula (2), R 2 is hydrogen or-CO 2 R, wherein R is one selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, and n-pentyl.
5. The method of claim 1, wherein the molar ratio of the catalyst to the compound of formula (2) is 1:20 to 1:5.
6. The method of claim 1, wherein the molar ratio of the catalyst to the compound of formula (2) is 1:15-1:5 or 1:10-1:5.
7. The method of claim 1, wherein the molar ratio of persulfate to the compound of formula (2) is 1:1 to 1.5:1.
8. The process of claim 1, wherein the dehydroaromatization reaction is carried out in the presence of a solvent and the solvent is selected from one or more of water, methylene chloride, dichloroethane, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, toluene, xylene, chlorobenzene, acetonitrile, benzonitrile, t-butanol, N-hexane, N-heptane, cyclohexane.
9. The method of claim 1, wherein the dehydroaromatization reaction has a reaction temperature of 20 to 120 ℃.
10. The method of claim 1, wherein the dehydroaromatization reaction has a reaction temperature of 30 to 90 ℃.
11. The method of claim 1, wherein the dehydroaromatization reaction takes 3 to 24 hours.
12. The method of claim 1, wherein the dehydroaromatization reaction has a reaction time of 6 to 12 hours.
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