JPH0125748B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for producing α,β-unsaturated-δ-lactones, which are extremely important as fragrance substances. More specifically, for example, the following formula (3) However, in the formula, R represents a C ₁ to C ₁₂ linear or branched alkyl group, a C ₇ to _{C 8} aralkyl group, or a C ₃ to _{C 6} cycloalkyl group. -alkyl-2
- 4-hydroxy-2-alkyl-1- represented by the above formula (2), which can be obtained by catalytic reduction of cyclopenten-1-ones in the presence of a catalyst.
The following formula (1) is characterized by subjecting cyclopentanones to an oxidation and dehydration reaction in the presence of a peracid. However, in the formula, R has the same meaning as described above, and relates to a novel method for producing α,β-unsaturated-δ-lactones represented by: The α,β-unsaturated lactones represented by the above formula (1) are known flavor substances that are extremely important and widely used as food flavors. For example, 2-decene-5-olide included in the above formula (1) is
It is the main component of the bark oil of Cry-ptocaria massoia and is also known as massoia lactone. Also sugar millet (Sacclarum officinarum var.
It is also found in butter (NC ₀ 310) and as the main flavor component of butter, and is an important flavor substance widely used as a food flavor. Conventionally, a few proposals have been made regarding the synthesis of α,β-unsaturated-δ-lactones represented by the above formula (1) including the above-mentioned 2-decene-5-olide, but none of them involve starting materials. The method is unsatisfactory in terms of performance, operation, yield, etc., and no proposal that is industrially fully satisfactory has been known to date. As a conventional proposal, for example, the method shown in the process diagram below (Agr.Biol.Chen., 32.1016 (1968)) is known. The above method requires multiple steps and complicated operations, the raw materials used are expensive, and the yield in each step is low, so it is not satisfactory as an industrial method. The present inventors conducted research in order to overcome the defects and disadvantages of the conventional methods as described above and provide an improved method for producing the compound of formula (1). As a result, the defects and disadvantages of the conventional proposals have been overcome, and 4-hydroxy-2-alkyl-2-cyclopenten-1-one represented by the above (3) can be easily produced in two steps at low cost and in high yield. It has been discovered that the compound of formula (1) can be produced industrially at a high rate. Accordingly, an object of the present invention is to provide a novel method for industrially advantageous production of the α,β-unsaturated lactone represented by the formula (1), which is useful as an aroma and flavor imparting or modulating agent. The objects and many other objects and advantages of the present invention will become more apparent from the following description. The 4-hydroxy-2-alkyl-2-cyclopenten-1-one represented by the formula (3), which can be advantageously used to produce the compound of the formula (2), which is the starting material of the present invention, is 1978 related to
Title of the invention filed on November 28th: "2-Substituted-hydroxycyclopentenones and their production method" (Application number 54-153004, Japanese Patent Application Laid-Open No. 1977-77232, 54
-153005, Japanese Unexamined Patent Publication No. 56-77237). α, β− represented by the above formula (1) in the present invention
A process diagram for producing unsaturated -δ-lactones can be shown, for example, as shown below. (In the formula, R has the same meaning as defined above.) The 4-hydroxy-2-alkyl-1-cyclopentanones represented by the above formula (2) are the 4-hydroxy-2-alkyl represented by the above formula (3). -2-
It can be easily produced by catalytic hydrogen reduction of cyclopenten-1-one in the presence of a catalyst. The above reaction may be carried out in an organic solvent if desired. Catalysts used in the reaction include, for example, palladium-based catalysts such as palladium with a carrier such as palladium black and palladium-carbon, and colloidal palladium; rhodium-based catalysts such as colloidal rhodium and rhodium carbon; nickel with a carrier such as diatomaceous earth; Examples include nickel-based catalysts such as Raney nickel. Examples of the organic solvent used in the reaction include alcohols such as methanol and ethanol; ethers such as dioxane and tetrahydrofuran; and any mixtures thereof. The hydrogen pressure in the above reaction can be carried out in a wide range, but for example, from about atmospheric pressure to about 100 Kg/cm ² , more preferably from about atmospheric pressure to about 50 Kg/cm ²
A range of degrees can be exemplified. The reaction temperature is preferably in the range of about 20°C to about 80°C. After the completion of the above reaction, the 4-hydroxy-2-alkyl-1-cyclopentanones of the above formula (2) can be obtained in high yield and purity by, for example, separating the catalyst and distilling off the solvent. can. If desired, further purification can be carried out by employing methods such as recrystallization, vacuum distillation, and column chromatography. In order to synthesize the α,β-unsaturated-γ-lactones represented by the above formula (1) of the present invention, 4-hydroxy-2-alkyl-1-cyclopentanones represented by the above formula (2) are synthesized. can be easily synthesized, for example, by using an organic or inorganic peracid and reacting under Bayer-Villiger reaction conditions, whereby lactonization by oxidation and dehydration reaction proceed simultaneously. The reaction can be carried out in good yield and with excellent selectivity, for example, by reacting the compound of formula (2) with a peracid in an inert solvent. The reaction temperature may be, for example, about 0°C to about 80°C, and more preferably about 20° to about 45°C. The reaction time can be appropriately selected depending on the reaction temperature, the type of peracid, etc., and can be, for example, a reaction time of several hours to several weeks. Examples of peracids used in the reaction include inorganic peracids such as hydrogen peroxide and persulfuric acid; organic peracids such as peracetic acid, perbenzoic acid, m-chloroperbenzoic acid, and monoperphthalic acid. can be exemplified.
Examples of the amount of these peracids to be used include about 1 to about 20 times the molar amount of the compound of formula (2), more preferably about 2 to 10 times the molar amount. Can be done. Furthermore, in order to promote the peroxidation reaction caused by peracid, in addition to peracid, a trace amount of an inorganic or organic acid such as sulfuric acid, hydrofluoric acid, perchloric acid, p-toluenesulfonic acid, etc. may be added as a catalyst. good. Further, the above-mentioned inert solvent can be appropriately selected depending on the peracid used and the type of product. For example, water,
Alkaline aqueous solution, ethanol, ether, chloroform, methylene chloride, formic acid, acetic acid, acetic anhydride,
Examples include pyridine and appropriate mixtures thereof. There is no particular restriction on the amount used, but the amount used may be about 1 to about 40 times, more preferably about 5 to about 30 times the weight of the compound of formula (2) above. . After the completion of the above reaction, for example, the reaction product is poured into water, neutralized, extracted with an appropriate solvent, and the solvent layer is washed with water, dried, and concentrated to obtain α, β expressed by the above formula (1). -Unsaturated-δ-lactone can be obtained in high yield and purity. If desired, further purification can be carried out by employing means such as vacuum distillation and column chromatography. Example 1 Synthesis of 4-hydroxy-2-pentyl-1-cyclopentanone. 4-hydroxy-2-pentyl-2-cyclopentene-1 of formula (3) was placed in a reaction vessel equipped with a catalytic reduction device.
-one 25.2g (0.15mol), 5% palladium on carbon
Add 1.2 g and 50 ml of methanol, and shake while introducing hydrogen. Hydrogen absorption begins immediately,
As the theoretical amount of hydrogen absorption is approached in about 4 hours, the shaking is stopped when the absorption rate decreases. The palladium on carbon is separated, methanol is distilled off, and the mixture is distilled under reduced pressure to obtain 23 g (yield: 90%) of colorless and transparent 4-hydroxy-2-pentyl-1-cyclopentanone. Boiling point 130°~137°C/1mmHg. The structure is IR,
Confirmed by NMR and MS. Example 2 Synthesis of 2-decene-5-olide. 10.2 g (10.06 mol) of 4-hydroxy-2-pentyl-1-cyclopentanone of formula (2) in the flask,
Add 81 g of 40% peracetic acid, 360 ml of acetic acid, and 1.5 g of p-toluenesulfonic acid, and leave in a thermostat in a dark room at 35°C for 60 hours. Pour the reaction into ice water and extract with ether. After drying, the ether was distilled off and distilled under reduced pressure to obtain 8.7 g of 2-decene-5-olide. Boiling point 130-134℃/1mmHg Yield 87%. The structure is IR,
Confirmed by NMR and MS. Example 3 Synthesis of 4-hydroxy-2-butyl-1-cyclopentanone. 4-hydroxy-2-butyl-2-cyclopenten-1-one in a reaction vessel equipped with a catalytic reduction device.
153 g (1 mole), rhodium carbon 4.5 g, and dioxane 150 c.c. were charged, and while introducing hydrogen, the reaction was carried out at a hydrogen pressure of 5 to 10 Kg/cm ² and a reaction temperature of 15 to 40°C, until the theoretical amount of hydrogen was absorbed. It ends when it gets hot. After the reaction, the rhodium carbon is separated, the dioxane is distilled off, and the mixture is distilled under reduced pressure to obtain 140 g (yield: 90%) of 4-hydroxy-2-butyl-1-cyclopentanone. Boiling point 124°~128°C/1mmHg structure is IR,
Confirmed by NMR and MS. Example 4 Synthesis of 2-nonene-5-olide. 4-hydroxy-2-butyl-1- in the flask
Cyclopentanone 77.5g (0.5mol), 40% peracetic acid
60 g, acetic acid 400 ml, and sulfuric acid 3 g, and left in a dark room constant temperature bath at 30°C for 50 hours. Pour the reaction into ice water and extract with ether. After drying, remove the ether and distill under reduced pressure to obtain 2-nonene-5-olide64
get g. Boiling point 125°~129°C/1mmHg Yield 85%.
The structure was confirmed by IR, NMR, and MS. Example 5 Using the same procedure as in Examples 1 and 2 or Examples 3 and 4, the results of experiments conducted on various R groups are shown in the table below.

[Table] Example 6 Using the same method as in Examples 1 and 2 or Examples 3, 4, and 5, the experimental results for the following R groups are shown in the table below.

【table】

Claims (1)

[Claims] 1. The following formula (2) However, in the formula, R represents a C ₁ to C ₁₂ linear or branched alkyl group, a C ₇ to _{C 8} aralkyl group, or a C ₃ to _{C 6} cycloalkyl group. -alkyl-1
- The following formula (1) characterized by subjecting cyclopentanones to an oxidation-dehydration reaction in the presence of a peracid. However, in the formula, R has the same meaning as above. A method for producing α,β-unsaturated-δ-lactones represented by: 2 The following formula (3) However, in the formula, R represents a C ₁ to C ₁₂ linear or branched alkyl group, a C ₇ to _{C 8} aralkyl group, or a C ₃ to _{C 6} cycloalkyl group. -alkyl-2
-Cyclopenten-1-ones are subjected to catalytic hydrogen reduction in the presence of a catalyst to form the following formula (2): However, in the formula, R has the same meaning as above, and 4-hydroxy-2-alkyl-1 represented by
- The following formula (1) is characterized by forming cyclopentanones and subjecting the compound of formula (2) to an oxidation and dehydration reaction in the presence of a peracid. However, in the formula, R is a method for producing α,β-unsaturated-δ-lactones represented by the same meaning as above.