JPS6257173B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing cyclopentenolones, and more specifically, the present invention relates to a method for producing cyclopentenolones, and more specifically, [In the formula, R ₁ is an alkyl group having up to 6 carbon atoms,
Alkenyl group, alkynyl group or general formula with up to 6 carbon atoms that does not have an unsaturated bond at the end of the bond

Represents a group represented by [Formula]. R ₂ here represents a hydrogen atom, a methyl group or a halogen atom. ] The present invention relates to a new method for producing cyclopentenolones shown in the following. Cyclopentenolones represented by the general formula () above are alcohol components of useful agricultural chemicals, and various methods are known for their synthesis, some of which are actually used industrially. However, this method is not necessarily satisfactory in terms of yield, operational complexity, environmental problems, etc. Among them, a synthesis method via a furan compound similar to the present invention is (R: allyl, n-butyl, cyclohexyl,
phenyl, 2-thienyl, p-tolyl) via the 4-substituted-5-hydroxy-5-
A method for obtaining cyclopentenolone (R: allyl group) by obtaining a methyl-3-oxocyclopentene compound (3) and then treating it with neutral alumina is known (G. Piancatelli et al., Tetrahedron (Tetrahedron) Volume 34, 2775-2778,
(1978)). However, with this method, Table 1 on page 2776 of the same document
When R represents a phenyl group, 2-thienyl group or p-tolyl group, that is, for an aromatic or heterocyclic compound as described in
Intermediate 4-substituted-5-hydroxy-5-
Although methyl-3-oxocyclopentene compound (3) can be obtained in a short time and in a relatively high yield, furan in which R is a substituent having no unsaturated bond at its bond end, as in the target compound of the present invention, With carbinol compounds, the reaction is difficult to proceed, and 4-substituted-
The yield of 5-hydroxy-5-methyl-3-oxocyclopentene compound (3) is extremely low and takes a long time, therefore, as a method for producing cyclopentenolone represented by the above general formula (), It is difficult to put it into practical use. Under these circumstances, as a result of various studies, the present inventors found the general formula () [In the formula, R ₁ has the same meaning as above. ] Directly from the furancarbinol compound shown by
The present invention has been completed by discovering a method for producing cyclopentenolones represented by the general formula (2) in an extremely high yield and very advantageous in terms of industrial operation. That is, the first aspect of the present invention is to prepare a furancarbinol compound represented by the general formula () in an aqueous solvent,
This is a method for producing cyclopentenolones represented by the general formula (), characterized in that the reaction system is maintained in the presence of a metal salt and the reaction system is maintained even after the furancarbinol compound is consumed. Furthermore, the second aspect of the present invention is the formula () 5-methylfurfural represented by the formula () R ₁ MX () [wherein R ₁ has the same meaning as above, and M is
It represents Mg, Zn or Al2/3 atom, and X represents chlorine atom, bromine atom or iodine atom. ] is reacted with an organometallic halide represented by the formula () to obtain a furan carbinol compound represented by the general formula (), which is then treated in an aqueous solvent in the presence of a metal salt to form the furan carbinol compound. This is a method for producing cyclopentenolones represented by the general formula (), characterized in that the reaction system is maintained even after the cyclopentenolone is consumed. Each step of the present invention will be explained below in order.
The first step of the present invention is a compound of the general formula () R ₁ X () [wherein R ₁ and X have the same meanings as above. ] A step of reacting an organometallic halide represented by the general formula () obtained by reacting a metal with a halogen compound represented by the formula () and 5-methylfurfural to synthesize a carbinol compound represented by the general formula (). In this step, 1-halogenated-2-alkene derivative, 1-halogenated-2
-Synthesizing organometallic halides of alkyl derivatives and 1-halogenated-2-benzyl derivatives,
- When reacting with methylfurfural, it is necessary to suppress the formation of Wurtz-type compounds due to coupling reactions and isomerized byproducts due to rearrangement reactions. Specifically, in the case of allyl halides, magnesium must be suppressed. A low concentration of allyl halide is slowly added dropwise using an ether solvent. In the case of propargyl halides, care must be taken such as using aluminum and mercury salts to suppress isomerized by-products.
Specifically, this process involves preparing a metal piece with or without activation treatment and a solvent (if the metal is used without activation treatment, add a small amount of iodine and then add the solvent) and dilute it with the solvent. The organic metal halide represented by the general formula () was synthesized by dropping the 5-halide diluted with a solvent.
After synthesizing the compound represented by the general formula () by dropping methylfurfural or dropping 1/10 of the charged amount of halide diluted with a solvent, 9/10 of the remaining charged amount This is carried out by dropping a mixture of a certain amount of a halide and 5-methylfurfural diluted with a solvent. In the second step of the present invention, the furan carbinol compound represented by the general formula () obtained above is treated in an aqueous solvent in the presence of a metal salt, and even after the furan carbinol compound is consumed, By subsequently holding the reaction system, cyclopentenolones represented by the general formula () are obtained. A feature of the present invention is that this second step is carried out in an aqueous solvent. The aqueous solvent mentioned here may include water alone or a small amount of an organic solvent such as toluene, xylene, diisopropyl ether, benzene, acetone, tetrahydrofuran, dioxane, etc., and the reaction is carried out in such an aqueous solvent. It has been discovered that cyclopentenolones represented by the general formula () can be conveniently obtained by this method. That is, according to the above-mentioned known literature, when the reaction is carried out in the presence of zinc chloride in an acetone solvent containing a small amount of water, the cyclopentenolones, which are the target compounds of the present invention, cannot be obtained;
-Substituted-5-hydroxy-5-methyl-3-oxocyclopentene compound (3) is obtained, and in addition, as in the target compound of the present invention, R ₁ does not have an unsaturated bond at its bond end. When it is a group, the yield is also extremely low. On the other hand, in the method of the present invention carried out in an aqueous solvent, the general formula ()
The above 4-substituted-5-hydroxy-5-methyl-3-oxocyclopentene compound (3) is also produced from the carbinol compound represented by, but the reaction continues after the raw material carbinol compound is consumed. By maintaining the system, cyclopentenolones represented by the general formula () can be obtained in extremely high yields. Moreover, according to the present invention, even when magnesium bromide, which is said to have no catalytic ability in the reaction described in the above-mentioned known literature, is used, the reaction proceeds in a short time and with a high yield. In the present invention, specific examples of R ₁ in the compound represented by the general formula () include a methyl group, a propyl group, a hexyl group, a cyclohexyl group, an allyl group,
Examples include 4-pentenyl group, propargyl group, benzyl group, p-methyl-benzyl group, p-chloro-benzyl group and the like. Further, the metal salts used in the present invention are magnesium salts, manganese salts, copper salts, cobalt salts, or zinc salts, such as magnesium chloride, magnesium bromide, magnesium sulfate, magnesium nitrate, manganese chloride, manganese nitrate, and copper sulfate. , cobalt acetate, zinc chloride, and the like. The amount of such metal salt to be used is 0.01 to 100 times the mole of the compound represented by the general formula (), preferably 0.1 to 100 times the mole.
The amount is 10 times the mole, more preferably 0.5 to 2 times the mole. In the present invention, the pH during the reaction is important, and the pH at the initial stage of the reaction is preferably in the range of 3 to 7, more preferably in the range of 3 to 6, and still more preferably in the range of 3.5 to 5.8. Of course, conditions outside this range may be used, but if the conditions are too acidic, by-products will increase, and if the conditions are too alkaline, the reaction rate will be significantly slowed down. The pH may be maintained until the end of the reaction without any particular adjustment, but in order to shorten the reaction time, the point at which the compound represented by the general formula () is consumed (before this point is defined as the initial stage of the reaction, and thereafter (called the late reaction stage), the pH is raised higher than the initial value.
It is preferable to maintain the ratio between 5 and 10, more preferably between 6.5 and 9, and even more preferably between 6.5 and 7.5. In the present invention, a wide variety of known acids and bases can be used for pH control.Specifically, acids include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, organic acids such as acetic acid and p-toluenesulfonic acid, and phosphorous acids. Examples include acidic metal salts such as sodium dihydrogen acid and sodium hydrogensulfite, and acidic ion exchange resins. Specific examples of the base include hydroxides of alkali metals such as sodium and potassium, alkaline earth metals such as calcium and barium, basic salts such as carbonates, bicarbonates, and acetates, triethylamine, Examples include amines such as pyridine, basic ion exchange resins, and the like. It is also possible to use acid-base buffer solutions using these. Furthermore, the amount of water solvent used in the present invention is preferably 0.5 to 100 times, preferably 5 to 40 times, the weight of the compound represented by the general formula (). The reaction temperature is usually 20°C to 200°C, preferably 80°C to 150°C. Specifically, this step involves dissolving or suspending a compound represented by the general formula () in an aqueous solvent in which a metal salt is dissolved, raising the temperature, and then reacting while adjusting the pH of the reaction solution between 3 and 7. Then, when the compound represented by the general formula () is consumed, the pH is adjusted to 5 to 10, and the reaction is carried out for several hours. The present invention will be specifically explained below using Examples. Example 1 Pour 1500 ml of water, raise the temperature to 100°C and reflux. Next, a solution prepared by dissolving 48 g of 5-methyl-2-furyl-allyl-carbinol and 63 g of MgCl ₂ .6H ₂ O in 320 ml of water was added dropwise over a period of 2.5 hours and 3.5 hours, respectively.
At that time, the pH of the reaction solution was 10% monopotassium phosphoric acid aqueous solution.
The pH was controlled to be between 5.8 and 5.5 with 1N sodium hydroxide solution. The pH stopped changing around 1.5 hours after the start of the reaction. After the dropwise addition of the MgCl ₂ aqueous solution was completed, the mixture was stirred under reflux at 100° C. for 4.5 hours at pH 5.5. Next, 1N aqueous sodium hydroxide was added to raise the pH to 6.8, and the mixture was stirred under reflux at 100°C for 6 hours. This is 40℃
After cooling to 640g of salt, add 500ml of toluene.
Extracted 4 times. After drying the extract over anhydrous magnesium sulfate, toluene was distilled off under reduced pressure at 60°C.
43.3g of oil was obtained. Next, distill this at 1.2mmHg and 130-132℃.
38.4 g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield: 80% Example 2 Charge 200 ml of water, dissolve 17 g of MgCl ₂ .6H ₂ O therein, and then add 13.0 g of 5-methyl-2-furyl-allyl-carbinol. This was heated to 100℃, refluxed, and mixed with 2N-hydrochloric acid water and 1N-NaOH water to pH 5.0 ~
The mixture was stirred under reflux for 8 hours while maintaining the temperature at 5.2. Next, the pH was raised to 7.3 with 1N-NaOH water, and the mixture was stirred under reflux for 3 hours. After cooling to 40°C, add 70g of common salt and extract 4 times with 80ml of toluene. After drying the extract over anhydrous magnesium sulfate, toluene was distilled off under reduced pressure at 60°C to obtain 11.9 g of an oily substance. Next, distill this at 1.2mmHg and 130-132℃.
10.2 g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield: 78% Example 3 100 ml of water is charged and 6.8 g of MgCl ₂ .6H ₂ O is dissolved therein, and then 5 g of 5-methyl-2-furyl-propargyl-carbinol is added. This at 100℃
The mixture was heated to 100%, refluxed, and kept at pH 3.8 to 4.1 with 1N hydrochloric acid and 1N NaOH, and stirred under reflux for 8 hours. next
The pH was raised to 7.3 with 1N NaOH water, and the mixture was refluxed for 3 hours.
After cooling to 40℃, add 35g of salt and 50ml of toluene.
Extract 4 times. After drying the extract over anhydrous magnesium sulfate, toluene was distilled off at 60° C. under reduced pressure to obtain 4.6 g of an oily substance. Next, using 60 g of silica gel, ethyl acetate-n-hexane (1
It was developed in two volumes. First, high boilers flow out, and then a small amount of unreacted 5-methyl-2-furyl-
Propargyl-carbinol flows out and, much later, the desired 2-propargyl-3-methyl-4-hydroxy-2-cyclopentenone flows out, and this fraction is concentrated to
-Methyl-4-hydroxy-2-cyclopentenone (3.3 g) was obtained. Yield 66% Examples 4 to 11 Using 5 g of the following furancarbinol compound,
The same operation as in Example 3 was carried out under the following conditions to obtain each cyclopentenolone.

【table】

[Table] Example 12 1 g of 5-methyl-2-furyl-allyl-carbinol was charged, and then 1.9 g of MgBr ₂ 6H ₂ O was added to 40 ml.
A solution dissolved in water was added thereto, the temperature was raised to 100°C, the mixture was refluxed, the pH was adjusted to 5.8 with 0.1N NaOH water, and the mixture was stirred under reflux for 5.5 hours. The pH at that time was 3.6. Then 0.1N
When the pH was raised to 7.4 with NaOH water and stirred under reflux for 1.5 hours, the pH was 5.7. Furthermore, PH7.0 with 0.1N NaOH water
The pH was 6.2 after stirring under reflux for 1.5 hours. Further, the pH was raised to 6.6 with 0.1N NaOH, and the mixture was stirred under reflux for 30 minutes, and the pH was 6.4. After cooling, salt 12
g and extracted four times with 30 ml of ether. After drying the extract over anhydrous magnesium sulfate, the ether was distilled off under reduced pressure at 40°C, and the resulting residue was added to 10 g of silica gel.
2-allyl-3-methyl-4-
0.55 g of hydroxy-2-cyclopentenone was obtained. Yield: 55% Example 13 1 g of 5-methyl-2-furyl-allyl-carbinol was charged, then a solution of 0.9 g of ZnCl ₂ dissolved in 40 ml of water was added, the temperature was raised to 100°C, and the mixture was refluxed. ,
Add a few drops of 0.1N NaOH water to bring the pH to 4.5, then add 0.1N
I added 0.3ml of NaOH water, but the pH remained at 4.5.
When this was stirred under reflux for 11 hours, the pH became 4.2. After cooling, 12 g of common salt was added, and the mixture was extracted four times with 30 ml of ether. After washing the extract with saturated NaHCO ₃ water and drying over anhydrous magnesium sulfate, the ether was distilled off under reduced pressure at 40°C. 2
0.58 g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield: 58% Example 14 39.3g of magnesium scraps and 400ml of ether
Add a small amount of iodine and stir. At around room temperature, about 10 drops of allyl bromide (167.8 g) were added, and the mixture was stirred until the pale yellow color of iodine disappeared. After cooling, the remaining allyl bromide was added dropwise over 4 hours while maintaining the temperature at 0 to 5°C, and the mixture was stirred for 30 minutes. Next, add 84.5 g of 5-methylfurfural to 200 g of ether.
ml of the solution was added dropwise over 1.5 hours while maintaining the temperature at 0 to 5°C, and the mixture was further stirred for 1 hour while keeping it warm. to this
Cool 500ml of 20% NH ₄ Cl water on ice to 10°C, then heat to 10-20°C.
The mixture was poured into the ether solution of the metal complex in 20 minutes while maintaining the temperature. After stirring at room temperature for 1 hour, the ether layer was separated, the aqueous layer was extracted twice with 200 ml of ether, the ether layers were combined, washed with 30 ml of saturated NaHCO ₃ water, and then dried.
Dry with MgSO ₄ and concentrate under reduced pressure at 40°C.
124.3g of oil was obtained. This was rectified at 4 mmHg and 60-61°C to obtain 106.7 g of 5-methyl-2-furyl-allyl-carbinol. Yield: 91% Next, using this, the same operation as in Example 1 was carried out to obtain 2-allyl-3-methyl-4-hydroxy-
2-cyclopentenone was obtained. Yield 72.8% from 5-methylfurfural Example 15 7.4 g of magnesium scraps and 40 ml of ether are charged, and then a small amount of iodine is added. At around 20℃,
Approximately 10 drops of a solution of 21.4 g of allyl chloride dissolved in 40 ml of ether were added and stirred until the pale yellow color of iodine disappeared. After cooling, the remaining ether solution of allyl chloride was added dropwise over 4 hours while maintaining the temperature at 0 to 5°C.
The mixture was stirred and kept warm for 1 hour. Next, a solution of 22.0 g of 5-methylfurfural dissolved in 100 ml of ether was added to
The mixture was added dropwise over 2 hours while maintaining the temperature at °C, and the mixture was stirred for 1 hour while keeping it warm. To this was added an aqueous solution in which 30 g of NH ₄ Cl was dissolved under ice-cooling over 20 minutes, and after stirring for 1 hour, unreacted magnesium was removed through Celite, and 100 g of sodium chloride was added to the solution.
g was added to separate the ether layer. Water layer is 200ml
Extract 3 times with ether and combine the ether layers to 30ml.
After washing with saturated aqueous NaHCO ₃ , it was dried over 50 g of anhydrous Na ₂ SO ₄ , and then concentrated under reduced pressure at 40° C. to obtain 27.9 g of an oil. This was rectified at 9mmHg and 92℃, and 21.9g
5-methyl-2-furyl-allyl-carbinol was obtained. Yield 72.1% Next, using this, the same operation as in Example 2 was carried out to obtain 2-allyl-3-methyl-4-hydroxy-
2-cyclopentenone was obtained. Yield 56.2% from 5-methylfurfural Example 16 1.54 g of aluminum powder, 35 mg of HgCl ₂ and a small amount of iodine were charged and heated at 150°C for 10 minutes. After cooling, 20 ml of tetrahydrofuran was charged and 9.6 g of propargyl bromide was prepared at 30°C. was added dropwise over a period of 4 hours, and 1
The mixture was kept warm and stirred for an hour. After cooling in an acetone-dry ice bath, a solution prepared by dissolving 9.2 g of 5-methylfurfural in 20 ml was added dropwise over 3 hours while maintaining the temperature at -10°C or lower. Next, the temperature was raised to 30℃, stirred for 30 minutes, and then heated to 0.
The mixture was cooled to 0.degree. C., and a solution of 10.6 g of NH ₄ Cl dissolved in 40 ml of water was added over 20 minutes. After stirring for 30 minutes, 100 ml of 30% NaCl water was added, and the mixture was extracted three times with 400 ml of ether. The ether layers were combined and washed with 60 ml of saturated NaHCO ₃ water, then anhydrous.
It was dried over MgSO ₄ and concentrated under reduced pressure at 50° C. to give 8.8 g of an oil. 120 g of silica gel was then developed with ethyl acetate-n-hexane (2 volumes to 5 volumes) to yield 8.2 g of 5-methyl-2-furyl-propargyl-carbinol. Yield: 65% Next, using this, the same operation as in Example 3 was carried out to obtain 2-propargyl-3-methyl-4-hydroxy-2-cyclopentenone. Yield from 5-methylfurfural: 43% Example 17 7.3 g of magnesium scraps and 30 ml of ether are charged, a small amount of iodine is added, and the mixture is stirred at room temperature. About 10 drops of a solution of 21.3 g of methyl iodide dissolved in 40 ml of ether were added to this, and the mixture was stirred until the pale yellow color of iodine disappeared. Next, the methyl iodide solution was heated between 22°C and 35°C at 1.5°C.
The mixture was added dropwise over a period of time and stirred at room temperature for 1 hour. Then 5-
A solution of 15.4 g of methylfurfural dissolved in 60 ml of ether was added dropwise over 30 minutes, and the mixture was stirred for 1 hour at room temperature.
Add 60 ml of saturated NH ₄ Cl water to this over 20 minutes, stir for 30 minutes, filter through Celite, remove unreacted magnesium, separate the ether layer, extract the aqueous layer twice with 100 ml of ether, and combine the ether layers. Saturated NaHCO ₃ water 20
ml, dried over anhydrous MgSO ₄ , and the solvent was distilled off under reduced pressure at 40° C. to obtain 13.5 g of oil. This is 10
11.8 g of 5-methyl-
2-furyl-methyl-carbinol was obtained. yield
67% Next, using this, the same operation as in Example 4 was carried out to obtain 2-methyl-3-methyl-4-hydroxy-
2-cyclopentenone was obtained. Yield from 5-methylfurfural: 42.2% Example 18 2.8 g of magnesium chips and 12 ml of ether are charged, a small amount of iodine is added, and the mixture is stirred at room temperature. Approximately 8.6 g of propyl chloride dissolved in 20 ml of ether
10 drops were added and stirred until the pale yellow color of iodine disappeared.
Next, this propyl chloride solution was added dropwise over 2 hours, and the mixture was stirred at room temperature for 1 hour. Next, add 10 g of 5-methylfurfural dissolved in 50 ml of ether to this.
The mixture was added dropwise over a period of time and stirred at room temperature for 1 hour. Further, 50 ml of saturated NH ₄ Cl water was added to this over 20 minutes, stirred for 30 minutes, filtered through Celite to remove unreacted magnesium, the ether layer was separated, the aqueous layer was extracted twice with 100 ml of ether, and the ether layers were combined. After washing with 20 ml of saturated NaHCO ₃ water, it was dried over anhydrous MgSO ₄ and the solvent was distilled off at 40° C. under reduced pressure to obtain 12.8 g of an oil. This was developed using 150 g of silica gel with ethyl acetate-n-hexane (2 volumes to 5 volumes), and 11.3 g of 5-methyl-2
-furyl-propyl-carbinol was obtained. yield
81% Next, using this, the same operation as in Example 5 was carried out to obtain 2-propyl-3-methyl-4-hydroxy-2-cyclopentenone. Yield 57.5% from 5-methylfurfural Examples 19 to 21 Using the following halogen compounds, the same operation as in Example 18 was carried out to obtain each furan carbinol compound represented by the general formula (). The same treatments as in Examples 6, 7, and 8 were carried out using the respective compounds to obtain the corresponding cyclopentenolone represented by the general formula ().

[Table] Volume *2 5〓Yield from methylfurfural Example 22 5.5 g of magnesium shavings, 5.5 g of powdered magnesium, and 100 ml of ether are charged, a small amount of iodine is added, and the mixture is stirred under reflux. About 10 drops of a solution of 19.3 g of p-chlorobenzyl chloride dissolved in 120 ml of ether were added and stirred until the pale yellow color of iodine disappeared. Next, the remaining p-chlorobenzyl chloride solution was added dropwise over 5 hours, and after stirring for 1 hour, 5-methylfurfural was added.
A solution of 10 g dissolved in 50 ml of ether was added dropwise over 2 hours and stirred for 1 hour. This was then added with 50 mL of saturated NH ₄ Cl water.
ml over 20 minutes, stirred for 30 minutes, filtered through Celite to remove unreacted magnesium, separated the ether layer, extracted the aqueous layer twice with 100 ml of ether, combined the ether layers, and washed with 20 ml of saturated NaHCO ₃ solution. , anhydrous _MgSO4
The solvent was distilled off at 40° C. under reduced pressure to obtain 25.1 g of oil. This was developed using 300 g of silica gel with ethyl acetate-n-hexane (2 volumes to 5 volumes) to obtain 21.6 g of 5-methyl-2-furyl-p-chlorobenzyl-carbinol. Yield 83% Next, using this, the same operation as in Example 9 was carried out to obtain 2-p-chlorobenzyl-3-methyl-4-
Hydroxy-2-cyclopentenone was obtained. Yield 68.9% from 5-methylfurfural Examples 23 to 24 The same operation as in Example 22 was carried out using the following halogen compounds to obtain each furancarbinol compound represented by the general formula (). Each of these compounds was treated in the same manner as in Examples 10 and 11 to obtain the corresponding cyclopentenolone represented by the general formula ().

[Table] Volume *2 5 Yield example from methylfurfural 25 Pour 200 ml of water and dissolve 6.18 g of MnCl ₂ 4H ₂ O. To this, add 5 g of 5-methyl-2-furyl-allyl-carbinol. Ta. The pH at this time was 4.8 (16°C). Then,
The temperature was raised to 100℃, and 1N NaOH water and 0.2N HCl were added.
The pH was maintained at 4.5 to 6.0 with water, and the mixture was stirred under reflux for 25 hours.
After cooling to 40℃ and neutralizing with 1N NaOH water, add 70% salt.
g and extracted four times with 80 ml of toluene. After drying the extract over anhydrous magnesium sulfate, toluene was distilled off at 60° C. under reduced pressure to obtain 3.8 g of an oily substance. Next, distill this at 0.05mmHg and 88-90℃ to obtain a 3.0
g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield: 61% Example 26 200 ml of water was charged to dissolve 6.5 g of MnCl ₂ .4H ₂ O, and 5 g of 5-methyl-2-furyl-allyl-carbinol was added thereto. Next, raise the temperature to 100℃,
The pH was maintained at 4.5 to 6.0 with 1N NaOH water and 0.2N HCl water, and the mixture was stirred under reflux for 8 hours. Next, the pH of the reaction solution was adjusted to 6.5 with 1N NaOH, and the mixture was stirred under reflux for 3 hours. After cooling to 40°C, 70g of common salt was added and extracted four times with 80ml of toluene. After drying the extract over anhydrous magnesium sulfate, heat at 60°C.
Toluene was distilled off under reduced pressure to obtain 3.9 g of an oily substance. Next, distill this at 0.05mmHg and 88-90℃ to obtain 3.1
g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield 62% Example 27 Add 200 ml of water and add _3.45 g of Co (CH ₃ COO) 2.4H ₂ O
was dissolved, and 5 g of 5-methyl-2-furyl-allylcarbinol was added thereto. Next, when this was heated to 100°C, the pH was 6.2. The pH was maintained at 5.5 to 6.0 with 1N NaOH water and 1N HCl water, and the mixture was stirred under reflux for 14 hours. After cooling to 40℃, add 70% salt.
g and extracted four times with 80 ml of toluene. After drying the extract over anhydrous magnesium sulfate, toluene was distilled off at 60° C. under reduced pressure to obtain 3.6 g of an oily substance. Next, distill this at 0.05mmHg and 88-90℃ to obtain 2.9
g of 2-allyl-3-methyl-4-hydroxy-2-cyclopentenone was obtained. Yield 58%.

Claims (1)

[Claims] 1. General formula [In the formula, R ₁ is an alkyl group having up to 6 carbon atoms,
It represents an alkenyl group, an alkynyl group, or a group represented by the general formula [Formula] having up to 6 carbon atoms, which does not have an unsaturated bond at the bond end. R ₂ here represents a hydrogen atom, a methyl group or a halogen atom. ] A furancarbinol compound represented by is treated in an aqueous solvent in the presence of a metal salt selected from the group consisting of magnesium salts, manganese salts, copper salts, cobalt salts and zinc salts, so that the furancarbinol compound is consumed. A general formula characterized by the fact that the reaction system continues to be maintained even after [In the formula, R ₁ has the same meaning as above. ] A method for producing a cyclopentenolone. 2. The method according to claim 1, wherein the treatment is carried out at 20 to 200°C. 3. Claim 1 or 2, in which the treatment is carried out at a pH of 3 to 7, and after the furancarbinol compound is consumed, the PH is raised higher than the initial value and maintained at a pH of 5 to 10. The method described in. 4 Process in the pH range of 3 to 6, and then maintain it afterward.
The method according to claim 3, which is carried out at a pH in the range of 6.5 to 9. 5 formula 5-methylfurfural and the general formula R ₁ MX [wherein R ₁ is an alkyl group with up to 6 carbon atoms, an alkenyl group with up to 6 carbon atoms without an unsaturated bond at the bond end, an alkynyl group, or a general Represents a group represented by the formula [Formula]. R ₂ here represents a hydrogen atom, a methyl group or a halogen atom. M represents a Mg, Zn or Al 〓 atom, and X represents a chlorine atom, a bromine atom or an iodine atom. ] by reacting with an organometallic halide represented by the general formula [In the formula, R ₁ has the same meaning as above. ] is obtained, and then treated in an aqueous solvent in the presence of a metal salt selected from the group consisting of magnesium salts, manganese salts, copper salts, cobalt salts and zinc salts to obtain the furancarbinol compound represented by A general formula characterized by the fact that the reaction system continues to be maintained even after the nol compound is consumed. [In the formula, R ₁ has the same meaning as above. ] A method for producing a cyclopentenolone.