Method for producing 1-alkenyl ether compound

Abstract

This method for producing a 1-alkenyl ether compound comprises obtaining a compound represented by formula (2) by dehydrochlorinating a compound represented by formula (1) at 90-110ºC in the presence of cyclopentyl methyl ether, potassium hydroxide, and t-butanol. (In formulae (1) and (2), R1 represents a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C2-C6 alkenyl group, a substituted or unsubstituted C2-C6 alkynyl group, a substituted or unsubstituted C3-C6 cycloalkyl group, or a substituted or unsubstituted phenyl group, and R2 represents a C1-C6 alkyl group. In formula (2), the wavy line represents a single bond with an uncertain stereostructure.)

Description

Method for producing 1-alkenyl ether compounds

[0001] The present invention relates to a method for producing 1-alkenyl ether compounds. This application claims priority to Japanese Patent Application No. 2023-167772, filed on September 28, 2023, the contents of which are incorporated herein by reference.

[0002] 1-Alkenyl ether compounds are synthetic equivalents of aldehyde compounds. Physical properties such as boiling point can be changed by replacing the atom or atomic group bonded to the O atom in the 1-alkenyl ether compound. 1-Alkenyl ether compounds are useful as raw materials for synthesizing pharmaceuticals, agricultural chemicals, polymers, etc.

[0003] Various methods for producing 1-alkenyl ether compounds from chloroether compounds by dehydrochlorination using a base are known. For example, Non-Patent Document 1 discloses an example in which a compound having a 2-chloro-3-methyl-3-butenyl group is dehydrochlorinated with a palladium complex-sodium acetate to convert it into a compound having a 3-methyl-1,3-butadienyl group.

[0004] Patent Document 1 discloses a production method including a step of dehydrochlorinating a compound represented by formula (A) to obtain a compound represented by formula (B).

[0005] Patent Document 2 discloses a production method including a step of reacting a compound represented by formula (C) with a reducing agent to obtain a compound represented by formula (D).

[0006] JP 2012-20954 A JP 2022-138156 A

[0007] Suzuki et al., "A new synthesis method for 1,3-dienes by ene-type chlorination and palladium-catalyzed dehydrochlorination," Journal of the Chemical Society of Japan, 1985 (3), pp.552-557

[0008] An object of the present invention is to provide an efficient method for producing 1-alkenyl ether compounds.

[0009] As a result of extensive investigations to achieve the above object, the present invention has been completed, including the following aspects.

[0010] [1] A method for producing an 1-alkenyl ether compound, comprising dehydrochlorinating a compound represented by formula (1) (hereinafter, sometimes referred to as compound (1)) in the presence of cyclopentyl methyl ether, potassium hydroxide, and t-butanol at 90°C to 110°C to obtain a compound represented by formula (2) (hereinafter, sometimes referred to as compound (2)).

[0011] (In formula (1), R １ represents a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C2-6 alkenyl group, a substituted or unsubstituted C2-6 alkynyl group, a substituted or unsubstituted C3-6 cycloalkyl group, or a substituted or unsubstituted phenyl group; R ２ represents a C1-6 alkyl group.

[0012] (In formula (2), R 1 and R 2 indicates the same as those in formula (1). The wavy line indicates an undefined stereo bond.

[0013] According to the method for producing a 1-alkenyl ether compound of the present invention, a 1-alkenyl ether compound useful as a raw material for medicines, agricultural chemicals, polymers, etc. can be efficiently obtained.

[0014] One embodiment of the method for producing an 1-alkenyl ether compound of the present invention comprises dehydrochlorinating compound (1) in the presence of cyclopentyl methyl ether (formula (3)), potassium hydroxide, and t-butanol at 90°C to 110°C to obtain compound (2).

[0015]

[0016] The compound (1) used in this embodiment is represented by formula (1).

[0017]

[0018] In formula (1), R １represents a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C2-6 alkenyl group, a substituted or unsubstituted C2-6 alkynyl group, a substituted or unsubstituted C3-6 cycloalkyl group, or a substituted or unsubstituted phenyl group. １ is preferably a substituted or unsubstituted C3-6 cycloalkyl group. ２ represents a C1-6 alkyl group.

[0019] In the present invention, the term "unsubstituted" refers to only the core group. When the name of the core group alone is used without the term "substituted," it means "unsubstituted" unless otherwise specified. On the other hand, the term "substituted" means that any hydrogen atom in the core group has been replaced with a group (substituent) of the same or different structure as the core group. Therefore, a "substituent" is another group bonded to the core group. The number of substituents may be one or more. The two or more substituents may be the same or different. A term such as "C1-6" indicates that the core group has 1 to 6 carbon atoms, for example. This number of carbon atoms does not include the number of carbon atoms in the substituent. For example, a butyl group having an ethoxy group as a substituent is classified as a C2 alkoxy C4 alkyl group. The "substituent" is not particularly limited as long as it is chemically permissible and provides the effects of the present invention.

[0020] Examples of groups that can serve as "substituents" include: C1-6 alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, n-pentyl, and n-hexyl; C2-6 alkenyl groups such as vinyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-2-propenyl, and 2-methyl-2-propenyl; C2-6 alkynyl groups such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, and 1-methyl-2-propynyl;

[0021] C3-6 cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups; aryl groups such as phenyl, tolyl, xylyl, trimethylphenyl, and naphthyl groups; phenyl C1-6 alkyl groups such as benzyl and phenethyl groups; 3- to 6-membered heterocyclyl groups; 3- to 6-membered heterocyclyl C1-6 alkyl groups;

[0022] hydroxyl groups; C1-6 alkoxy groups such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, i-butoxy, and t-butoxy groups; C2-6 alkenyloxy groups such as vinyloxy, allyloxy, propenyloxy, and butenyloxy groups; C2-6 alkynyloxy groups such as ethynyloxy and propargyloxy groups; phenoxy and naphthoxy groups; phenyl C1-6 alkoxy groups such as benzyloxy and phenethyloxy groups; 5- to 6-membered heteroaryloxy groups such as thiazolyloxy and pyridyloxy groups; 5- to 6-membered heteroaryl C1-6 alkyloxy groups such as thiazolylmethyloxy and pyridylmethyloxy groups;

[0023] a formyl group; a C1-6 alkylcarbonyl group such as an acetyl group or a propionyl group; a formyloxy group; a C1-6 alkylcarbonyloxy group such as an acetyloxy group or a propionyloxy group; a benzoyl group; a C1-6 alkoxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonyl group or a t-butoxycarbonyl group; a C1-6 alkoxycarbonyloxy group such as a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, an i-propoxycarbonyloxy group, an n-butoxycarbonyloxy group or a t-butoxycarbonyloxy group; a carboxyl group;

[0024] halogeno groups such as a fluoro group, a chloro group, a bromo group, and an iodo group; C1-6 haloalkyl groups such as a chloromethyl group, a chloroethyl group, a trifluoromethyl group, a 1,2-dichloro-n-propyl group, a 1-fluoro-n-butyl group, and a perfluoro-n-pentyl group; C2-6 haloalkenyl groups such as a 2-chloro-1-propenyl group and a 2-fluoro-1-butenyl group; C2-6 haloalkynyl groups such as a 4,4-dichloro-1-butynyl group, a 4-fluoro-1-pentynyl group, and a 5-bromo-2-pentynyl group; C1-6 haloalkoxy groups such as a trifluoromethoxy group, a 2-chloro-n-propoxy group, and a 2,3-dichlorobutoxy group; C2-6 haloalkenyloxy groups such as a 2-chloropropenyloxy group and a 3-bromobutenyloxy group; C1-6 haloalkylcarbonyl groups such as a chloroacetyl group, a trifluoroacetyl group, or a trichloroacetyl group;

[0025] amino groups; C1-6 alkyl-substituted amino groups such as methylamino, dimethylamino, and diethylamino; anilino and naphthylamino groups; phenyl C1-6 alkylamino groups such as benzylamino and phenethylamino; formylamino groups; C1-6 alkylcarbonylamino groups such as acetylamino, propanoylamino, butyrylamino, and i-propylcarbonylamino; C1-6 alkoxycarbonylamino groups such as methoxycarbonylamino, ethoxycarbonylamino, n-propoxycarbonylamino, and i-propoxycarbonylamino; unsubstituted or substituted aminocarbonyl groups such as aminocarbonyl, dimethylaminocarbonyl, phenylaminocarbonyl, and N-phenyl-N-methylaminocarbonyl; imino C1-6 alkyl groups such as iminomethyl, (1-imino)ethyl, and (1-imino)-n-propyl; Substituted or unsubstituted N-hydroxyimino C1-6 alkyl groups such as an N-hydroxy-iminomethyl group, a (1-(N-hydroxy)-imino)ethyl group, a (1-(N-hydroxy)-imino)propyl group, an N-methoxy-iminomethyl group, or a (1-(N-methoxy)-imino)ethyl group; an aminocarbonyloxy group; a C1-6 alkyl-substituted aminocarbonyloxy group such as an ethylaminocarbonyloxy group or a dimethylaminocarbonyloxy group;

[0026] a mercapto group; a C1-6 alkylthio group such as a methylthio group, an ethylthio group, an n-propylthio group, an i-propylthio group, an n-butylthio group, an i-butylthio group, an s-butylthio group, or a t-butylthio group; a C1-6 haloalkylthio group such as a trifluoromethylthio group or a 2,2,2-trifluoroethylthio group; a phenylthio group or a naphthylthio group; a 5- or 6-membered heteroarylthio group such as a thiazolylthio group or a pyridylthio group;

[0027] C1-6 alkylsulfinyl groups such as methylsulfinyl, ethylsulfinyl, and t-butylsulfinyl groups; C1-6 haloalkylsulfinyl groups such as trifluoromethylsulfinyl and 2,2,2-trifluoroethylsulfinyl groups; phenylsulfinyl groups; 5- to 6-membered heteroarylsulfinyl groups such as thiazolylsulfinyl and pyridylsulfinyl groups;

[0028] C1-6 alkylsulfonyl groups such as methylsulfonyl, ethylsulfonyl, and t-butylsulfonyl groups; C1-6 haloalkylsulfonyl groups such as trifluoromethylsulfonyl and 2,2,2-trifluoroethylsulfonyl groups; phenylsulfonyl groups; 5- to 6-membered heteroarylsulfonyl groups such as thiazolylsulfonyl and pyridylsulfonyl groups; C1-6 alkylsulfonyloxy groups such as methylsulfonyloxy, ethylsulfonyloxy, and t-butylsulfonyloxy groups; C1-6 haloalkylsulfonyloxy groups such as trifluoromethylsulfonyloxy and 2,2,2-trifluoroethylsulfonyloxy groups;

[0029] Tri-C1-6 alkyl-substituted silyl groups such as trimethylsilyl, triethylsilyl, and t-butyldimethylsilyl; triphenylsilyl group; cyano group; and nitro group.

[0030] In addition, any hydrogen atom in these "substituents" may be substituted with a group of a different structure. In this case, examples of the "substituent" include a C1-6 alkyl group, a C1-6 haloalkyl group, a C1-6 alkoxy group, a C1-6 haloalkoxy group, a halogeno group, a cyano group, and a nitro group.

[0031] Furthermore, the above-mentioned "3- to 6-membered heterocyclyl group" contains 1, 2, 3, or 4 heteroatoms selected from the group consisting of nitrogen, oxygen, and sulfur atoms, in a chemically permissible number as ring-constituting atoms. The heterocyclyl group may be either monocyclic or polycyclic. In the case of a polycyclic heterocyclyl group, as long as at least one ring is a heterocycle, the remaining rings may be saturated alicyclic, unsaturated alicyclic, or aromatic. Examples of the "3- to 6-membered heterocyclyl group" include 3- to 6-membered saturated heterocyclyl groups, 5- to 6-membered heteroaryl groups, and 5- to 6-membered partially unsaturated heterocyclyl groups.

[0032] Examples of the "3- to 6-membered saturated heterocyclyl group" include an aziridinyl group, an epoxy group, a pyrrolidinyl group, a tetrahydrofuranyl group, a thiazolidinyl group, a piperidyl group, a piperazinyl group, a morpholinyl group, a dioxolanyl group, and a dioxanyl group.

[0033] Examples of "5-membered heteroaryl groups" include pyrrolyl, furyl, thienyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, and tetrazolyl groups. Examples of "6-membered heteroaryl groups" include pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, and triazinyl groups. Examples of "5- to 6-membered partially unsaturated heterocyclyl groups" include 5-membered partially unsaturated heterocyclyl groups such as pyrrolinyl, dihydrofuranyl, dihydrothiophenyl, imidazolinyl, pyrazolinyl, oxazolinyl, isoxazolinyl, thiazolinyl, and isothiazolinyl groups; and 6-membered partially unsaturated heterocyclyl groups such as dihydropyranyl.

[0034] R １ and R ２ The "C1-6 alkyl group" in the formula may be a straight chain or a branched chain. １Examples of the C1-6 alkyl group in the formula (I) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an i-propyl group, an i-butyl group, an s-butyl group, a t-butyl group, an i-pentyl group, a neopentyl group, a 2-methylbutyl group, a 2,2-dimethylpropyl group, and an i-hexyl group.

[0035] R １ Examples of the "C2-6 alkenyl group" in the above formula include vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-methyl-2-propenyl group, 2-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-methyl-2-butenyl group, 2-methyl-2-butenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, and 5-hexenyl group.

[0036] R １ Examples of the "C2-6 alkynyl group" in the above formula include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, and a 1-methyl-2-propynyl group.

[0037] R １ Examples of the "C3-6 cycloalkyl group" in the above formula include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0038] R １Preferred substituents on the "C1-6 alkyl group," "C2-6 alkenyl group," and "C1-6 alkynyl group" in the above formula (I) can include halogeno groups such as fluoro, chloro, bromo, and iodo; C1-6 alkoxy groups such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, i-butoxy, and t-butoxy; C1-6 haloalkoxy groups such as difluoromethoxy, trifluoromethoxy, 2,2-difluoroethyl, and 2,2,2-trifluoroethyl; phenyl groups; phenyl groups substituted with halogeno groups, C1-6 alkyl groups, C1-6 haloalkyl groups, or C1-6 haloalkoxy groups, such as 4-chlorophenyl, 4-methylphenyl, 4-trifluoromethylphenyl, and 4-trifluoromethoxyphenyl; or cyano groups.

[0039] R １ Substituents on the "C3-6 cycloalkyl group" and "phenyl group" in the above formula are preferably halogeno groups such as fluoro, chloro, bromo, and iodo; C1-6 alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, n-pentyl, and n-hexyl; C1-6 haloalkyl groups such as difluoromethyl, trifluoromethyl, perfluoroethyl, 1,2,2,3,3,3-hexafluoropropyl, perfluoropropyl, and 1,2,3,3,3-pentafluoro-2-(trifluoromethyl)propyl; C1-6 alkoxy groups such as methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, i-butoxy, and t-butoxy; Examples include a C1-6 haloalkoxy group such as a difluoromethoxy group, a trifluoromethoxy group, a 2,2-difluoroethyl group, or a 2,2,2-trifluoroethyl group; or a cyano group.

[0040] In the production method of this embodiment, compound (1) is R １ is a cyclopropyl group, R ２is an n-butyl group (compound (1a): (2-butoxy-1-chloroethyl)cyclopropane) can be preferably used.

[0041]

[0042] The compound (1) used in this embodiment may be synthesized by the inventors themselves using a known method, or may be synthesized by another person using some method and commercially available. The method for synthesizing compound (1) is not particularly limited. For example, a compound having an epoxy group can be reacted with an alcohol to obtain a β-hydroxy ether compound, which can then be chlorinated to obtain a β-chloro ether compound.

[0043]

[0044] The potassium hydroxide used in this embodiment may be a commercially available product. Commercially available potassium hydroxide typically has a potassium hydroxide (KOH) content of about 85% by mass to about 95% by mass. The potassium hydroxide used in this embodiment may be a mixture of anhydrous potassium hydroxide and potassium hydroxide monohydrate. The potassium hydroxide used in this embodiment may also contain potassium carbonate, which is produced by absorbing water and carbon dioxide from the air. The potassium hydroxide used in this embodiment is not particularly limited in shape, and examples include flakes, powder, and granules. The amount of potassium hydroxide (KOH) used is, for example, preferably 2.0 to 10.0 mol, more preferably 2.0 to 5.0 mol, and even more preferably 3.0 to 4.5 mol per mol of compound (1). Potassium hydroxide is preferably supplied to the reactor little by little to prevent a rapid temperature rise due to the heat of reaction. The amount of potassium hydroxide supplied may be controlled by monitoring the temperature inside the reactor.

[0045] The t-butanol used in this embodiment may be a commercially available product that is generally available. t-butanol has a boiling point of 82.4°C. The amount of t-butanol used is, for example, preferably 0.1 to 1.5 mol, more preferably 0.2 to 1.0 mol, and even more preferably 0.2 to 0.4 mol, per mol of potassium hydroxide. t-butanol is preferably supplied to the reactor little by little in order to suppress a sudden temperature rise due to the heat of reaction. The amount of t-butanol supplied may be controlled by monitoring the temperature inside the reactor.

[0046] The cyclopentyl methyl ether used in this embodiment may be a commercially available product. Cyclopentyl methyl ether has a boiling point of 106°C and an azeotropic point with water of approximately 83.7°C. The amount of cyclopentyl methyl ether used is not particularly limited, but is preferably 10 to 500 parts by weight, more preferably 50 to 200 parts by weight, and even more preferably 70 to 140 parts by weight, per part by weight of compound (1).

[0047] In this embodiment, an organic compound that does not affect the dechlorination reaction may be used as the solvent. Examples of such an organic compound include ethers such as tetrahydrofuran (boiling point 66°C), 2-methyltetrahydrofuran (boiling point 78°C), and dioxane (boiling point 101°C); and aromatic hydrocarbons such as toluene (boiling point 111°C) and xylene (boiling point 144°C).

[0048] During the dehydrochlorination reaction, the temperature in the reaction system is set to 90°C to 110°C. The temperature in the reaction system can be set, for example, preferably to 100°C to 110°C, more preferably to 105°C to 110°C, and even more preferably to 108°C to 110°C. During the dehydrochlorination reaction, the pressure in the reaction system can be set, for example, preferably to 0.1 to 1 MPa, and more preferably to 0.1 to 0.5 MPa. The time required for the dehydrochlorination reaction is not particularly limited, and can be set, for example, preferably to 1 hour to 24 hours, more preferably to 2 hours to 8 hours, and even more preferably to 2 hours to 4 hours. The dehydrochlorination reaction is preferably carried out under an inert gas atmosphere.

[0049] The compound (2) obtained by the dehydrochlorination reaction is represented by the formula (2). Compound (2) may be obtained in the form of a mixture of E and Z isomers due to the double bond.

[0050]

[0051] In formula (2), R 1 and R 2 indicate the same as those in formula (1). In formula (2), the wavy line indicates an undefined stereo bond. Compound (1a) can be dehydrochlorinated to obtain a compound represented by formula (2a) (compound (2a): (2-butoxyethenyl)cyclopropane).

[0052]

[0053] The liquid containing compound (2) obtained by the dehydrochlorination reaction can be used directly or after purification in the next step (e.g., the production process of pharmaceuticals, agricultural chemicals, polymers, etc.). Purification can be carried out by known methods. For example, purification can be carried out by extraction, crystallization, distillation, chromatography, etc., or by an appropriate combination of these methods.

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0055] Example 1: A 200 ml flask equipped with a reflux condenser and a stirrer was charged with 42 ml (0.36 mol) of cyclopentyl methyl ether (CPME) and 18 ml (0.19 mol) of t-butanol, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 12.6 g (0.19 mol) of powdered potassium hydroxide and 7.4 g (0.040 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 92°C and stirred at that temperature for 19 hours. The solution was then cooled to 15°C, and 80 ml of water was added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (upper layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield: 88.5 mol %) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate: 1.4 mol %).

[0056]

[0057] Example 2: A 200 ml flask equipped with a reflux condenser and a stirrer was charged with 40 ml (0.34 mol) of cyclopentyl methyl ether and 3.8 ml (0.040 mol) of t-butanol, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 13.3 g (0.203 mol) of powdered potassium hydroxide and 7.4 g (0.040 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 102°C and stirred at that temperature for 3.5 hours. The solution was then cooled to 15°C, and 80 ml of water was added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (upper layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield: 89.0 mol %) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate: 0.6 mol %).

[0058] Example 3: 27 ml (0.23 mol) of cyclopentyl methyl ether and 1.3 ml (0.014 mol) of t-butanol were placed in a 200 ml flask equipped with a reflux condenser and a stirrer, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 5.4 g (0.083 mol) of flaky potassium hydroxide and 5.0 g (0.027 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 108°C and stirred at that temperature for 3 hours. It was then cooled to 15°C, and 54 ml of water was added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (upper layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield: 92.0 mol %) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate: 0.8 mol %).

[0059] Comparative Example 1: 4 ml (0.043 mol) of t-butanol was placed in a 50 ml flask equipped with a reflux condenser and a stirrer, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 0.8 g (0.007 mol) of potassium t-butoxide and 0.5 g (0.003 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 80°C and stirred at that temperature for 5 hours. It was then cooled to 15°C, and 14 ml of water and 14 ml of methylene chloride were added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (lower layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield 46.8 mol%) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate 3.3 mol%).

[0060] Comparative Example 2: 4 ml (0.049 mol) of tetrahydrofuran was placed in a 50 ml flask equipped with a reflux condenser and a stirrer, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 0.8 g (0.007 mol) of potassium t-butoxide and 0.5 g (0.003 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 50°C and stirred at that temperature for 8 hours. It was then cooled to 15°C, and 14 ml of water and 14 ml of methylene chloride were added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (lower layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield 66.1 mol%) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate 7.3 mol%).

[0061] Comparative Example 3 20 ml (approximately 0.25 mol) of tetrahydrofuran was placed in a 100 ml flask equipped with a reflux condenser and a stirrer, and the liquid was cooled to 15°C. While maintaining the temperature at 15°C, 4.1 g (0.043 mol) of sodium t-butoxide and 3.7 g (0.020 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting liquid was warmed to 50°C and stirred at that temperature for 5 hours. The resulting liquid contained a very small amount of (2-butoxyethenyl)cyclopropane.

[0062] Comparative Example 4: A 100 ml flask equipped with a reflux condenser and a stirrer was charged with 14 ml (0.049 mol) of tetrahydrofuran and 6 ml (0.063 mol) of t-butanol, and the resulting solution was cooled to 15°C. While maintaining the temperature at 15°C, 2.8 g (0.043 mol) of powdered potassium hydroxide and 3.7 g (0.020 mol) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt% were added. The resulting solution was heated to 70°C and stirred at that temperature for 10 hours. It was then cooled to 15°C, and 40 ml of water was added and stirred for a while. The solution was then allowed to stand and separated to obtain an organic layer (upper layer). The organic layer contained (2-butoxyethenyl)cyclopropane (yield 34.2 mol%) and (2-butoxy-1-chloroethyl)cyclopropane (residual rate 20.0 mol%).

[0063] [Reference example]

[0064] 590 ml of n-butanol was placed in a 2000 ml flask equipped with a reflux condenser and a stirrer, and 60.5 g of potassium hydroxide (granular) and 70.2 g of 2-cyclopropyloxirane were added at room temperature. The resulting liquid was heated to 70°C and stirred at that temperature for 1 hour. It was then cooled to 5°C, and 417 ml of water was added. The pH was then adjusted to 1.0 with 35% hydrochloric acid and stirred for a while. The mixture was then allowed to stand and separated to obtain an organic layer (upper layer). The organic layer was distilled under reduced pressure to obtain 90.9 g (yield: 65.3 mol%) of 2-butoxy-1-cyclopropylethan-1-ol with a purity of 94.9 wt%.

[0065]

[0066] A 200 ml flask equipped with a stirrer was charged with 60 ml of methylene chloride, and 10.0 g of 2-butoxy-1-cyclopropylethan-1-ol with a purity of 94.9 wt % was added at room temperature. The liquid was then cooled to 5°C. While maintaining the temperature at 5°C, 8.6 g of thionyl chloride was added dropwise. After the addition was completed, the mixture was stirred for 5 hours. 75 ml of water was added to the resulting liquid, and the mixture was stirred for a while. The mixture was then allowed to stand and separated to obtain an organic layer (lower layer). The organic layer was washed with 5% aqueous sodium bicarbonate. The solvent was then distilled off to obtain 12.8 g (yield: 94.6 mol%) of (2-butoxy-1-chloroethyl)cyclopropane with a purity of 78.2 wt %. This was then rectified to obtain (2-butoxy-1-chloroethyl)cyclopropane with a purity of 95.9 wt %.

[0067] As shown by the above examples, the production method of the present invention makes it possible to efficiently obtain, in high yield, 1-alkenyl ether compounds that are useful as raw materials for pharmaceuticals, agricultural chemicals, polymers, etc.

[0068] It is possible to provide a novel method for efficiently producing 1-alkenyl ether compounds.

Claims

1. A compound represented by formula (1) (In formula (1), R １ represents a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C2-6 alkenyl group, a substituted or unsubstituted C2-6 alkynyl group, a substituted or unsubstituted C3-6 cycloalkyl group, or a substituted or unsubstituted phenyl group; R ２ represents a C1-6 alkyl group.) is dehydrochlorinated in the presence of cyclopentyl methyl ether, potassium hydroxide and t-butanol at 90°C to 110°C to obtain a compound represented by formula (2). (In formula (2), R 1 and R 2 The symbols are the same as those in formula (1). The wavy line represents a single bond of undefined configuration.

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