JPH09309857A - Production of 4-unsaturated aldehydes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce 4-unsaturated aldehydes useful as an intermediate for unsaturated alcohols, unsaturated carboxylic acids, saturated aldehydes, etc., in high yield by reacting enamines with specific olefins in the coexistence of an alkali metallic carbonate. SOLUTION: Compounds of formula I [R1 is H, an alkyl or an aryl; R2 and R3 are each a lower alkyl or an aryl; R2 and R3 may mutually be bonded together to form a ring (which may contain a hetero-atom such as N, O or S)] are brought into contact with a compound of formula II (R4 to R8 are each H, an alkyl or an aryl; X is a halogen or a sulfonate) and an alkali metallic carbonate to afford an unsaturated aldehyde of formula III. A compound of formula IV is preferred as the compound of formula I and a compound of formula V is preferred as the compound of formula II. For example, N,N- dimethyl-N-vinylamine is cited as the enamines of formula I and, e.g. acryloyl chloride is cited as the compound of formula II. For example, potassium carbonate is cited as the alkali metallic carbonate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing unsaturated aldehydes.

[0002]

BACKGROUND OF THE INVENTION 4-Unsaturated aldehydes are useful as synthetic intermediates for various compounds such as unsaturated alcohols, unsaturated carboxylic acids and saturated aldehydes, and fragrances. Conventionally,
The 4-unsaturated aldehydes include a method in which a saturated aldehyde is treated with a strong base and then reacted with an olefin such as allyl chloride.

However, this method has a problem in that an expensive strong base such as lithium diisopropylamide is used and a side reaction occurs due to aldol condensation between the saturated aldehydes as raw materials. Therefore, as a result of intensive studies in order to solve these problems, the present inventors have developed 4-unsaturated aldehydes by a novel reaction between an enamine and a specific olefin that is easily derived from a saturated aldehyde. A method that can be obtained is proposed in Japanese Patent Application No. 7-191827.

[0004]

The yield of 4-unsaturated aldehydes obtained by this method is not always sufficient, and further improvement has been desired. Therefore, an object of the present invention is to provide a method capable of obtaining 4-unsaturated aldehydes by a novel reaction between an enamine and a specific olefin which are easily derived from a saturated aldehyde.

[0005]

In order to solve the above problems, the present invention provides at least a compound represented by the general formula (1): R1CH = CHNR2R3 (1) [wherein R1 is a hydrogen atom, an alkyl group or An aryl group, which may have a substituent, R2 and R3
May be the same or different and each is a lower alkyl group or an aryl group, which may be bonded to each other to form a ring, in which case a hetero atom such as a nitrogen atom, an oxygen atom and a sulfur atom is formed in the ring. May be contained] and the compound represented by the general formula (2): R5R6C = CR4CR7R8X (2) [In the formula, R4, R5, R6, R7, and R8 may be the same or different, and are hydrogen. An atom, an alkyl group or an aryl group, which may have a substituent, and X is a halogen atom or a sulfonate group] and a carbonate of an alkali metal are generally brought into contact with each other. Formula (3): R7R8C = CR4CR5R6CHR1CHO (3) [wherein, R1 is as defined in the general formula (1), and R4, R5, R6, R7. Preliminary R8 provides a method for producing an unsaturated aldehyde represented by the general as defined in formula (2)].

In the above manufacturing method, the general formula (2)
The compound of the general formula (4):

CH ₂ = C (CH ₃ ) CH ₂ X (4)

It is preferable to use a compound represented by the formula [wherein X is as defined in the above general formula (2)].

Further, in the above production method, the compound of the general formula (5) is used as the compound of the general formula (1).

CH (CH ₃ ) ₂ CH = CHNR2R3 (5)

It is preferable to use a compound represented by the formula [wherein R2 and R3 are as defined in the above general formula (1)]. Further, in the above manufacturing method, it is preferable to use potassium carbonate as the alkali metal carbonate.

Hereinafter, the present invention will be described in detail.

In the general formula (1) representing the enamine which is a starting material in the method of the present invention, R1 is a hydrogen atom, an alkyl group or an aryl group. Examples of the alkyl group include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group,
Examples thereof include an octyl group, a nonyl group, a decyl group and isomers thereof, and an isopropyl group is preferable. The aryl group may be a phenyl group, o-, m- or p-
Examples thereof include a toluyl group and an α- or β-naphthyl group.
Further, these alkyl groups and aryl groups may have a substituent, for example, methoxy group, ethoxy group, phenoxy group, acetoxyl group, benzoyloxy group, N-acetylamino group, ethoxycarbonyl group, N, N-
Examples thereof include a dimethylcarbamoyl group. R1 and R
3 may be the same or different and is a lower alkyl group or an aryl group. Examples of the lower alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group and isomers thereof, and an aryl group. , Phenyl group,
Examples thereof include o-, m- or p-toluyl group and α- or β-naphthyl group. R3 and R4 may be bonded to each other to form a ring, in which case a hetero atom such as a nitrogen atom, an oxygen atom and a sulfur atom may be contained in the ring, for example, a pyrrolidine ring. , A piperidine ring, a morpholine ring, etc. may be formed. These enamines can be synthesized by known methods such as condensation reaction of aldehydes and amines. Examples of these methods are described in New Experimental Chemistry Course 14 Synthesis and Reactions of Organic Compounds (III), 1417 (1978).

Specific examples of the enamines represented by the general formula (1) include N, N-dimethyl-N-vinylamine, N, N-diethyl-N-vinylamine, N, N-dipropyl-N-vinylamine, N, N-dibutyl-N-vinylamine, N-methyl-N-phenyl-N-vinylamine, N-benzyl-N-methyl-N-vinylamine, N-vinylpyrrolidine, N-vinylpiperidine, N-vinylmorpholine, N , N-Dimethyl-N- (1-propenyl) amine, N, N-diethyl-N- (1-propenyl) amine, N- (1-propenyl) -N, N-dipropylamine, N, N-dibutyl -N- (1-propenyl) amine, N-methyl-N- (1-propenyl) -N-phenylamine, N-benzyl-N-methyl-N- (1-propenyl) amine, N- (1-propenyl ) Pyrrolidine, N- (1-propenyl)
Piperidine, N- (1-propenyl) morpholine, N- (1-butenyl) -N, N-dimethylamine, N- (1-butenyl) -N, N-diethylamine, N- (1-butenyl) -N, N-dipropylamine, N
-(1-butenyl) -N, N-dibutylamine, N- (1-butenyl) -N
-Methyl-N-phenylamine, N-benzyl-N- (1-butenyl) -N-methylamine, N- (1-butenyl) pyrrolidine, N- (1
-Butenyl) piperidine, N- (1-butenyl) morpholine, N,
N-dimethyl-N- (3-methyl-1-butenyl) amine, N, N-diethyl-N- (3-methyl-1-butenyl) amine, N- (3-methyl-1-
Butenyl) -N, N-dipropylamine, N, N-dibutyl-N- (3-
Methyl-1-butenyl) amine, N-methyl-N- (3-methyl-1-
Butenyl) -N-phenylamine, N-benzyl-N-methyl-N-
(3-methyl-1-butenyl) amine, N- (3-methyl-1-butenyl) pyrrolidine, N- (3-methyl-1-butenyl) piperidine,
N- (3-methyl-1-butenyl) morpholine, N, N-dimethyl-N-
(1-pentyl) amine, N, N-diethyl-N- (1-pentyl) amine, N- (1-pentyl) pyrrolidine, N- (1-pentyl) morpholine, N- (1-hexyl) -N, N-dimethylamine, N, N-diethyl-N- (1-hexyl) amine, N- (1-hexyl) pyrrolidine, N- (1-hexyl) morpholine, N, N-dimethyl-N-styrylamine, N , N-diethyl-N-styrylamine, N-styrylpyrrolidine, N-styrylmorpholine, N- (4-methoxy-3-methyl-1-butenyl) -N, N-dimethylamine, N- (4
-Methoxy-3-methyl-1-butenyl) morpholine, 5- (N, N-
Dimethylamino) -4-pentenoate methyl and the like, preferably, N, N-dimethyl-N- (3-methyl-1-butenyl) amine, N, N-diethyl-N- (3-methyl-1 -Butenyl) amine, N-
(3-Methyl-1-butenyl) -N, N-dipropylamine, N, N-dibutyl-N- (3-methyl-1-butenyl) amine, N-methyl-N-
(3-Methyl-1-butenyl) -N-phenylamine, N-benzyl
-N-methyl-N- (3-methyl-1-butenyl) amine, N- (3-methyl-1-butenyl) pyrrolidine, N- (3-methyl-1-butenyl)
It is piperidine, N- (3-methyl-1-butenyl) morpholine.

In the general formula (2) representing the olefins which are the starting materials in the method of the present invention, R4, R5,
R6, R7 and R8 may be the same or different,
A hydrogen atom, an alkyl group or an aryl group, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. R4 is a methyl group, R is preferably
5, R6, R7 and R8 are hydrogen atoms. Examples of the aryl group include phenyl group, o-, m- or p-toluyl group, α- or β-naphthyl group and the like. Further, these alkyl group and aryl group may have a substituent, for example, methoxy group, ethoxy group, phenoxy group, acetoxyl group, benzoyloxy group, N-
Acetylamino group, ethoxycarbonyl group, N, N-dimethylcarbamoyl group and the like can be mentioned. X is a halogen atom or a sulfonate group, and examples of the halogen atom include a chlorine atom, a bromine atom and an iodine atom,
Examples of the sulfonate group include a methanesulfonate group, a benzenesulfonate group, a toluenesulfonate group, and the like.

Specific examples of the olefins represented by the general formula (2) include allyl chloride, allyl bromide, allyl iodide, allyl methanesulfonate, methallyl chloride, methallyl bromide, methallyl iodide, methallyl methane. Sulfonate, methallyl benzene sulfonate, methallyl toluene sulfonate, 2-butenyl chloride, 2-butenyl bromide, 2-butenyl methane sulfonate, 3-methyl-2-butenyl chloride, 3-methyl-2-butenyl bromide, 3-methyl-2-bu Tenyl methanesulfonate, 2-pentenyl chloride, 2-pentenyl bromide, 2-
Pentenyl methanesulfonate, 3-chloro-1-butene, 3
-Bromo-1-butene, 3-chloro-1-phenyl-1-propene,
3-bromo-1-phenyl-1-propene, 4-methoxy-2-butenyl chloride, methyl 6-chloro-4-hexenoate and the like, preferably, methallyl chloride, methallyl bromide, methallyl iodide, They are methallyl methane sulfonate, methallyl benzene sulfonate, and methallyl toluene sulfonate.

The amount of the olefins used is not particularly limited, but is usually 0.1 to 10 moles, and particularly 0.5 to 1 mole of the enamine represented by the general formula (1).
-5 mol is preferable.

Examples of the alkali metal carbonate used in the method of the present invention include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate and the like, with potassium carbonate being preferred.

The amount of the carbonate used is 0.5 to 5 mol, and particularly preferably 1 to 3 mol, based on 1 mol of the enamine.

In the method of the present invention, a reaction solvent may or may not be used. As the reaction solvent, a solvent inert to the reaction can be used, and specific examples of such a reaction solvent include hexane, heptane, octane, and aliphatic hydrocarbon solvents such as cyclohexane,
Benzene, toluene, o-, m- or p-xylene,
Aromatic hydrocarbon solvents such as mesitylene, ether solvents such as ethyl ether, butyl ether, tetrahydrofuran, nitrile solvents such as acetonitrile, propionitrile, benzonitrile, ethanol, propanol, isopropanol, butanol, t-butanol, etc. Alcoholic solvents can be mentioned. These solvents can be used alone or in combination.

The reaction in the method of the present invention may be carried out continuously or batchwise in the liquid phase. The reaction temperature is usually about 0 to 200 ° C. The reaction time is usually about 0.1 to 50 hours, although it varies depending on the enamines and olefins used, the reaction temperature, and the like.

Since the reaction mixture obtained by the above reaction usually contains by-products, unreacted starting materials, etc., the 4-unsaturated aldehydes which are the object of the present invention are
It can be obtained by separating and purifying from this reaction mixture. The separation method used is not particularly limited, and for example,
Known separation methods such as distillation, adsorption, extraction, recrystallization and the like may be used.

The 4-unsaturated aldehydes obtained by the method of the present invention are useful as synthetic intermediates for various compounds such as unsaturated alcohols, unsaturated carboxylic acids and saturated aldehydes, and fragrances.

[0024]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Preparation of 2,4-Dimethyl-4-pentenal N, N-Dimethyl-N- (1-propenyl) was added to a 30 ml eggplant-shaped flask.
Amine 2.26 g (0.02 mol), methallyl chloride 6.51 g (0.072 m
ol), potassium carbonate 3.04 g (0.022 mol), acetonitrile 10
ml was charged and the mixture was heated to reflux for 11 hours. The reaction mixture was cooled to room temperature, 10 ml of water was added, and the mixture was refluxed at room temperature for 1 hour. After extraction with ethyl acetate, the extract was analyzed by gas chromatography to find that the yield of 2,4-dimethyl-4-pentenal was 2.64 g. Yield 94%.

Examples 2 to 7 Instead of N, N-dimethyl-N- (1-propenyl) amine, methallyl chloride, potassium carbonate, acetonitrile, Table 1
Table 1 shows the results using the raw materials and solvents shown in.

[0027]

[Table 1]

[0028]

INDUSTRIAL APPLICABILITY According to the method of the present invention, various compounds such as unsaturated alcohols, unsaturated carboxylic acids and saturated aldehydes can be prepared by reacting an enamine with a specific olefin in the presence of an alkali metal carbonate. 4-Unsaturated aldehydes useful as synthetic intermediates and fragrances can be obtained in high yield.

Claims (3)

[Claims] 1. At least general formula (1): R1CH = CHNR2R3 (1) [wherein, R1 is a hydrogen atom, an alkyl group or an aryl group, which may have a substituent, R2 And R3
May be the same or different and each is a lower alkyl group or an aryl group, which may be bonded to each other to form a ring, in which case a hetero atom such as a nitrogen atom, an oxygen atom and a sulfur atom is formed in the ring. May be contained] and the compound represented by the general formula (2): R5R6C = CR4CR7R8X (2) [In the formula, R4, R5, R6, R7, and R8 may be the same or different, and are hydrogen. An atom, an alkyl group or an aryl group, which may have a substituent, and X is a halogen atom or a sulfonate group] and a carbonate of an alkali metal are generally brought into contact with each other. Formula (3): R7R8C = CR4CR5R6CHR1CHO (3) [wherein, R1 is as defined in the general formula (1), and R4, R5, R6, R7. Preliminary R8 manufacturing method of unsaturated aldehyde represented by as in a 'defined by formula (2). 2. A compound represented by the general formula (2) is represented by the general formula (4): CH ₂ ═C (CH ₃ ) CH 2X (4) [wherein, X is a halogen atom or a sulfonate group. ] The manufacturing method of the unsaturated aldehyde of Claim 1 which uses the compound represented by these. 3. As the compound represented by the general formula (1), a compound represented by the general formula (5): CH (CH ₃ ) ₂ CH═CHNR2R3 (5) [wherein, R 2 and R 3 are the general formulas described above. It is as defined in (1)], The manufacturing method of unsaturated aldehyde of Claim 2 which uses the compound represented.