JPS6254417B2 - - 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 a straight chain, cyclic or branched alkyl group having up to 6 carbon atoms, a straight chain or branched anikenyl group having up to 6 carbon atoms, a straight chain having up to 6 carbon atoms, Cyclic or branched alkynyl group or general formula

Represents a group represented by [Formula]. Here, R ₂ represents a hydrogen atom, a methyl group or a halogen atom. ] This invention relates to a new method for producing cyclopentenolones shown in the following. The cyclopentenolones represented by the above general formula () are useful alcohol components of agricultural chemicals, and various methods for synthesizing them are known. Among them, a synthesis method via a furan compound similar to the present invention is (R: phenyl, n-hexyl, methyl, tert-butyl heptanate)
A method for obtaining a cyclopentenolone by obtaining a substituted-5-hydroxy-3-oxocyclopentene compound (3) and then treating it with alumina is known (G. Piancatelli et al., Tetrahedron, Vol. 35). , 135 (1979)) and (G.
Piancatelli et al., Tetrahedron Letters 39, 3555 (1976)). However, in this method, the intermediate 4-
It takes a long time of 24 hours to obtain a substituted-5-hydroxy-3-oxocyclopentene compound, and the yield is not always satisfactory. Therefore, it cannot be said that the method for producing cyclopentenolone represented by the general formula () is satisfactory. 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. ) We have discovered a method for producing cyclopentenolones represented by the general formula () directly in one step in an extremely high yield and extremely advantageous in terms of industrial operation, and have completed the present invention. did. That is, the present invention provides a furancarbinol compound represented by the general formula () in an aqueous solvent at pH 3 to
8 is a method for producing cyclopentenolones represented by the general formula (), which is characterized by carrying out a heat treatment in step 8. A feature of the present invention is that it 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 an acid in an acetone solvent containing a small amount of water, cyclopentenolones, which are the target compounds of the present invention, cannot be obtained, and the 4-substituted-5- Only the hydroxy-3-oxocyclopentene compound (3) is obtained, and the reaction takes a long time and the yield is not necessarily satisfactory. On the other hand, in the method of the present invention in which heat treatment is carried out in an aqueous solvent, it is surprisingly possible to directly convert the carbinol compound represented by the general formula () into a cyclopentenolone represented by the general formula () in one step and in extremely high yield. You can get similar results. 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,
α-methyl-allyl group, α-ethylallyl group, 4
-Pentenyl group, propargyl group, α-methyl-
Examples include propargyl group, benzyl group, p-methylbenzyl group, and p-chlorobenzyl group. In the present invention, the pH during the reaction is important, and the pH of the reaction is in the range of 3 to 8. If it is too acidic, the amount of by-products will increase, and if it is too alkaline, the reaction rate will be significantly slowed down. 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. Examples of bases 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, and toluethylamine. , amines such as pyridine, basic ion exchange resins, and the like. Moreover, acid-base buffer solutions using these can also be used. The amount of water solvent used in the present invention is based on the compound represented by the general formula ().
It is preferable to use 0.5 to 100 times the weight, preferably 5 to 80 times the weight. The reaction temperature is usually 20°C to 200°C, preferably 80°C to 180°C. Furthermore, metal salts and/or surfactants can also be used in the present invention, and their use is effective in shortening reaction time, improving yield, improving volumetric efficiency, and the like. The metal salt mentioned here is
Magnesium salts such as magnesium chloride and magnesium acetate; manganese salts such as manganese chloride and manganese nitrate; copper salts such as copper acetate and copper sulfate; cobalt salts;
Zinc salts, iron salts, nickel salts, etc. can be mentioned. Examples of the surfactant include cationic surfactants, nonionic surfactants, and amphoteric surfactants. The amount of the metal salt to be used is in the range of 0.001 to 0.2 times the mole, preferably 0.01 to 0.05 times the mole of the compound represented by the general formula (). Further, the amount of surfactant used is 0.1 to 20% by weight, preferably 1% by weight based on the compound represented by the general formula ().
-5% by weight. The present invention specifically relates to the general formula () in the presence or absence of a metal salt and/or a surfactant.
The reaction is carried out by dissolving or suspending the compound shown in an aqueous solvent and raising the temperature, and then reacting for 1 hour to 30 hours while adjusting the pH between 3 and 8. In addition, the compound represented by the general formula () which is _the starting material of the present invention has the general formula () R ₁ represents an atom. ] The compound represented by the general formula () R ₁ MX () [wherein R ₁ and X have the same meanings as above, and M is Mg, Zn or Represents Al2/3 atoms. ] It can be obtained by reacting the compound represented by the following with furfural. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 Dipotassium phosphate 0.56g and phosphoric acid 1 in 400ml water
1.77 g of potassium was dissolved (PH6.2, 20°C.). Charge 5 g of 2-furylallyl-carbinol and the above phosphate buffer into an autoclave, and raise the temperature to 180°C while stirring (heating time: 55
The mixture was stirred while keeping it warm for 4 hours (internal pressure: 9 Kg/cm ² ). Next, after cooling the reaction vessel on ice, 40 g of common salt was added, and the mixture was extracted four times with 100 ml of methyl isobutyl ketone.
The extract was concentrated under reduced pressure at 60°C, and methyl isobutyl ketone was distilled off to obtain 4.5 g of oil. Next, this was purified by column chromatography using 60 g of silica gel (developing solution: ethyl acetate/n-hexane (1 volume/2 volumes)) and 4.1 g of 2-
Allyl-4-hydroxy-2-cyclopentenone was obtained. Yield 82% IR data νc=o 1710 ^-1 cm νc=c 1650 ^-1 cm NMR data CDCl ₃ , 60MHz 7.32 (S, 1H, 3-H) 5.86 (complex m, 1H, -CH ₂ -CH =
CHaHb) 5.25 (m, 1H, -CH ₂ -CH= CHaHb ) 5.02 (m, 1H, -CH ₂ -CH=CHa Hb ) 4.63 (broad d, 1H, 4-H) 4.28 (broad s, 1H ,4-OH) 2.98(d,2H, -CH2 _- CH=CHaHb) 2.69(dd,1H,5-H) 2.42(dd,1H,5-H) Examples 2 to 4 Using 5 g of the following furancarbinol compound, the same operation as in Example 1 was performed under the following conditions to obtain each cyclopentenolone.

[Table] Example 5 500 ml of water and 2.0 g of potassium dihydrogen phosphate were placed in an autoclave, and the pH was adjusted to 5.1 (30°C) with 1N NaOH water. Next, 15 g of (α-methyl-allyl)-2-furyl carbinol was added, heated and stirred at 150°C for 5.5 hours, and after cooling, the pH was adjusted to 7.1 (30°C) with 1N NaOH water, and again at 150°C for 5 hours. The mixture was heated and stirred. Salt in the reaction solution
After adding 10 g of 2-(α-methyl-allyl)-
4-hydroxy-2-cyclopentenone 12g
I got it. Yield: 80% Boiling point: 88-90°C/0.12 mmHg Examples 6-7 Using 15 g of the following furan carbinol compound, the same operation as in Example 5 was carried out to obtain each cyclopentenolone compound.

【table】

[Table] Example 8 0.25 g of sodium acetate and 0.44 g of commercially available surfactant Bionin D-408 (polyoxyethylene alkyl phenyl ether manufactured by Takemoto Yushi Co., Ltd.) in 200 ml of water.
was dissolved and adjusted to pH 5.8 (20°C) with a 10-fold (V/V) diluted acetic acid aqueous solution. The entire amount of 2-furyl-allyl-carbinol and the above acetate buffer was charged into an autoclave, and the temperature was raised to 150°C with stirring (heating time 35°C).
minutes) The mixture was kept warm and stirred for 8 hours. Next, cool this reaction container with water, add 40g of common salt, and then add methyl isobutyl ketone.
Extracted 4 times with 80 ml. The extract was concentrated under reduced pressure at 60°C, and methyl isobutyl ketone was distilled off to obtain 4.6 g of oil. Next, this was purified by column chromatography using 60 g of silica gel (developing solution: ethyl acetate/n-hexane (1 volume/2
4.2 g of 2-allyl-4-hydroxy-2
- Cyclopentenone was obtained. Yield 84% Example 9 0.25 g of sodium acetate and MgCl ₂ in 200 ml of water.
0.27 g of 6H ₂ O was dissolved and prepared with a 10-fold diluted acetic acid aqueous solution so that the pH was 6.0 (20°C). Charge 5 g of 2-furylallyl-carbinol and the above acetate buffer into an autoclave.
The temperature was raised to 180°C with stirring, and the mixture was stirred while keeping it warm for 3.5 hours. Next, the reaction vessel was cooled with ice, 40 g of common salt was added, and methyl isobutyl ketone was distilled off to obtain 4.6 g of an oily substance. Next, this was purified by column chromatography using 60 g of silica gel (developing solution: ethyl acetate/n-hexane (1 volume/2 volumes)).
4.2 g of 2-allyl-4-hydroxy-2-cyclopentenone was obtained. Yield 84%

Claims (1)

[Claims] 1. General formula [In the formula, R ₁ is a straight chain, cyclic or branched alkyl group having up to 6 carbon atoms, a straight chain or branched alkenyl group having up to 6 carbon atoms, a straight chain having up to 6 carbon atoms, Represents a cyclic or branched alkynyl group or a group represented by the general formula [Formula]. Here, R ₂ represents a hydrogen atom, a methyl group or a halogen atom. ] A general formula characterized in that the furancarbinol compound represented by is heat-treated at pH 3 to 8 in an aqueous solvent in the presence or absence of a metal salt and/or a surfactant. [In the formula, R ₁ has the same meaning as above. ] A method for producing a cyclopentenolone.