JPS5811848B2 - 2-(1-alkenyl)-2-cyclobentenone - Google Patents

Description

Detailed Description of the Invention The present invention provides 2-(1-alkenyl)-2 of the following formula (1) useful as a jasmine-like fragrance substance and as a synthetic intermediate.
-Relating to a method for producing cyclobentenone.

However, in the formula, R1, R2, and R3 each represent a hydrogen atom or a lower alkyl group, and R2 and R3 may be taken together to form a cycloalkyl group.

More specifically, the present invention is based on the following formula (4), where R1, R2, and R3 each represent a hydrogen atom or a lower alkyl group, and R2 and R3 together form a cycloalkyl group. and R4 represents a lower alkyl group, and a compound represented by the following formula (3), where R represents an alkyl group, are subjected to a condensation reaction in the presence of a Lewis acid, Next, the following formula (1) is characterized by heating in the presence of an acid and in the presence of an organic base in an organic solvent. However, in the formula, R1, R2, and R3 have the same meaning as described in formula (4). The present invention relates to a method for producing 2-(1-alkenyl)-2-cyclobentenone represented by , .

Conventionally, 2-(1-alkenyl)-2-cyclobentenone has been produced by subjecting cyclobentenone and alkenyl bromide to a condensation reaction in liquid ammonia.

Since this reaction uses liquid ammonia, which is complicated and dangerous to operate and handle, it is necessary to carry out the reaction carefully using a liquid ammonium reactor, and it is completely unsuitable for implementation on an industrial scale.

The present inventors have determined that 2-(1-alkenyl) of the above formula (1)
-2-Cyclobentenone should be produced industrially advantageously (research results revealed that the compound represented by the formula (4) and the formula (
The compound represented by formula (1) can be easily condensed, and by heating this condensation reaction product in the presence of an acid and in the presence of an organic base, the compound of formula (1) can be industrially advantageously produced. We have discovered that it can be produced with good yield and purity using a simple procedure.

Furthermore, it has been found that according to the method of the present invention, 2-(1-alkenyl)-2-cyclobentenones, which have not been described in any literature, can be produced easily, in good yield, and with good purity, as shown in Examples later. Ta.

It is therefore an object of the present invention to include novel 2-(1-alkenyl)- compounds useful as perfume substances and synthetic intermediates.
The object of the present invention is to provide a method for producing 2-(1-alkenyl)-2-cyclobentenone, which can be industrially advantageously produced according to a new reaction method.

The above objects and many other objects and advantages of the present invention are
This will become clearer from the description below.

In the method of the present invention, the condensation reaction product derived from the compound of formula (4) and the compound of formula (3) is represented by the following formula (2), where R', R2 and R3 are each a hydrogen atom or a hydrogen atom. This oily liquid substance is presumed to be a compound represented by the following formula, in which R2 and R3 may be taken together to form a cycloalkyl group, and R4 is a lower alkyl group.

The above oily liquid substance is an α-bromoaliphatic or alicyclic aldehyde, an α-bromoaliphatic or alicyclic aldehyde represented by the following formula (4), where R1, R2, R3 and R4 have the same meanings as above. An acetal or ketal of a group ketone and 1-trialkylsiloxy-1-cyclobentenone represented by the following formula (3), where R is an alkyl group, preferably a C1 to C4 lower alkyl group. can be easily produced in high yield by condensation in the presence of a Lewis acid, preferably under an inert gas atmosphere, preferably in a solvent such as a halogenated hydrocarbon.

The production of the compound of formula (1) can be schematically illustrated as follows, in addition to the production of the compound of formula (2) above.

Condensation reaction product formula (2) γ-bromo β in the present invention
- When producing an alkoxyketone by the condensation reaction of the α-bromoacetal or α-bromoketal of the above formula (4) and the alkenosilylether of the above formula (3), the reaction is carried out in an inert solvent, preferably a halogenated It is preferable to carry out the reaction in a hydrocarbon solvent under an inert gas atmosphere.

Examples of such solvents include halogenated hydrocarbon solvents such as methylene chloride, ethane chloride, trichloroethylene, trichloropropylene, and carbon tetrachloride.

There are no special restrictions on the amount of solvent used, but for example, if the formula (
4) About 20 to about 80 times the weight of the compound, preferably about 50 times the weight of the compound
It can be used in an amount of ~70 times its weight.

Further, examples of the above-mentioned inert gas include inert gases such as nitrogen, argon, and helium.

The condensation reaction is carried out in the presence of a Lewis acid under low temperature conditions such as, for example, below about -30°C, preferably from about -80°C to about -30°C, more preferably from about -75°C to about -65°C, at a temperature of about 0. ．．
5 to about 7 hours, about 0.5 to about 5 hours, preferably about 2 to about 7 hours
The reaction can be carried out for about 5 hours.

Examples of the Lewis acid include titanium tetrachloride, tin tetrachloride, and aluminum chloride.

The reaction can be carried out, for example, by gradually dropping a Lewis acid catalyst into a solution of the compound of formula (4) in a halogenated hydrocarbon solvent, and then gradually adding a solution of the alkenosilyl ether of formula (3) in a halogenated hydrocarbon solvent. It can be done by dripping.

In the method of the present invention, for example, the γ-bromo β-alkoxyalkylcyclopentanone of the formula (2) obtained as described above is subjected to heat dealcoholization and dehydrobromination reaction in an organic solvent, thereby easily and The target compound formula (1) 2-(1-alkenyl)-2 was obtained in good yield and purity.
- cyclobentenone can be obtained.

At this time, it is not necessary to isolate the condensation product of formula (2).

If necessary, the target product of formula (1) can be produced simply by concentrating the condensation reaction product system, adding a nonpolar solvent, and heating. It is preferable to employ an operation of heating to .

In the condensation product of formula (2), when R1, R2, and R3 are lower alkyl groups, C1 to C4 lower alkyl groups are preferred, such as methyl, ethyl, rho, or 1
Examples include so-propyl, rho, 1so-, 5ec-1 or tert-butyl groups.

A preferred example of the case where R2 and R3 together form a cycloalkyl group is 2-(1-methoxy-2-bromocyclohexanyl)-2-cyclopentanone.

Examples of the lower alkyl group for P include the same lower alkyl groups as those mentioned above for R1, R2, and R3.

Particularly preferred is methyl or ethyl.

Thermal dealcoholization and dehydrobromination reactions are carried out in an organic solvent,
Preferably under an inert gas atmosphere such as nitrogen or argon,
Dealcoholization and dehydrobromation can be carried out by heating to the temperature.

At this time, it is preferable to carry out the reaction by adding a small amount of an acid such as paratoluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, or phosphoric acid to the system as a catalyst for promoting the dealcoholization and dehydrobromination reactions.

The amount added is, for example, about 1 wt% based on the condensation reaction product.
The amount may be about 5 wt%.

Also, by allowing a receptor for the eliminated hydrogen bromide, such as an organic base, to coexist in the reaction system, the double bond portion of the cyclobentenone ring where the eliminated hydrogen bromide was formed can be brominated. This is particularly preferable because it can avoid this risk.

Preferred examples of such organic bases include amines such as triethylamine, tributylamine, tripropylamine, pyridine, and triethanolamine.

These can be used alone or in combination.

The amount of such organic base used is about 7 % based on the condensation reaction product.
About 20 times to about 20 times the amount is sufficient.

The reaction temperature and time can be selected appropriately.

The organic solvent used in the present invention can be selected from a wide range, and polar-aprotic solvents such as chlorinated hydrocarbons, hydrocarbons, and amide solvents can be appropriately selected and used. Solvents can also be used.

In the method of the present invention, an example of a preferred embodiment of the thermal dealcoholization and dehydrobromination reaction is as follows: a compound of formula (4) and a compound of formula (3)
) in a hydrocarbon solvent, which may include a chlorinated hydrocarbon solvent, preferably under an inert gas atmosphere, in the presence of a promoting amount of an acid such as those exemplified above, e.g. After heating under reflux conditions, the solvent is distilled off and recovered under reduced pressure conditions, and in a polar aprotic solvent in the presence of an organic base, for example in a dimethylformamide-triethylamine (5:3 volume ratio) solution. about 6
An example is an embodiment in which heating is carried out at a temperature of 0 to about 100°C, preferably about 70 to about 90°C, particularly about 80°±5°C, for example, for about 5 hours.

Therefore, the method of the present invention is preferably carried out by heating in an organic solvent in an inert gas atmosphere in the presence of an acid, and then further heating in a polar aprotic solvent in the presence of an organic base. .

Specific examples of organic solvents include chlorinated hydrocarbons such as methylene chloride, ethane chloride, trichloroethylene, trichloropropylene, and carbon tetrachloride; hydrocarbons such as benzene, toluene, xylene, heptane, octane, and hexane. Classes: and N,N-dimethylformamide, hexamethylphosphoramide, N.

Polar aprotic solvents such as N-dimethylacetamide can be exemplified.

According to the method of the present invention, for example, a compound of formula (4) and a compound of formula (3)
From the compound via the compound of formula (2), the compound of formula (1) 2-
Approximately 80% (1-alkenyl)-2-cyclobentenone
It can be easily produced on an industrial scale with a high yield of over 90%.

Moreover, it is possible to obtain a compound included in the compound of formula (1) that has not been described in any literature.

Next, some embodiments of the method implementation of the present invention will be explained by examples.
It will be explained in more detail.

Example 1 2-bromobutyraldehyde dimethyl acetal (19
,71,0,1 mol) of methylene chloride (1000 ml)
A solution of 0.1 mol of titanium tetrachloride in methylene chloride (50 ml) is added dropwise to the solution at about -78° C. under an argon atmosphere.

Then cyclopentenyl trimethylsilyl ether (0.11 mol, 17.2 g) in methylene chloride (300
ml) solution dropwise at about -78°C, the reaction mixture was maintained at that temperature for 1 hour and allowed to react with stirring.

After the reaction, after treatment with cold saturated sodium bicarbonate, the organic layer is extracted with ether, and to the resulting oily liquid material after solvent recovery is added iooOml of toluene.

After adding another 0.5 g of para-toluenesulfonic acid,
Heat to reflux for 30 minutes under an argon atmosphere.

After recovering toluene under reduced pressure, 500 ml of N,N-dimethylformamide-triethylamine solution (5:3) was added, and the mixture was reacted by heating at 80° C. for 5 hours under an argon atmosphere.

After the reaction, the mixture is cooled and the organic layer is washed with 1300 ml of ether and washed three times with 1500 ml of cold water.

The ethereal extracts of the organic layer and wash water were combined, then I
1500 mg of NNN acid group aqueous solution was then washed with cold water.

In this way, 2-(1-butenyl)-2-cyclobentenone, which has not been described in any literature, could be obtained in a yield of 78% by distillation under reduced pressure.

According to the NMR spectrum of this product (δ, Ppm,
S=Singlet, bs=broad Single
t.

d=doublet, t=triplet, m=mul
ti-plet), methyl group 0.03 (t), methylene group 2.33-2.70 (m), olefin proton group H
b5.9(d), olefin proton group Ha)6.64
(m), an olefin proton group of 7.19 (bs), and the IR spectrum shows an absorption based on a carbonyl group at 1720 cm-' and a conjugated carbonyl group at 1660 cm-1 (
It had an absorption based on C=0 group), an absorption based on a conjugated diene at 1600 cm, and an absorption based on a transolefin at 980 cm, and it was confirmed that it was 2-(1-butenyl)-2-cyclobentenone. .

This IR chart is shown in attached figure a1.

Example 2 The reaction was carried out under exactly the same reaction conditions as in Example 1, except that 2-bromopropionaldehyde diethyl acecool was used instead of 2-bromobutyraldehyde dimethyl acecool.

In this way, 2-(1-propenyl)-2-cyclobentenone could be synthesized with a yield of 73%.

According to the NMR spectrum of this product (δ, the value is the same as in Example 1), the methyl group is 1.80 (d), the methylene group is 2.16 to 2.66, and the olefin proton group Hb is 5.9.
7(d), He6.64(m), He7.19(bs)
As in Example 1, it has absorption based on conjugated carbonyl, conjugated diene, and trans olefin, and has absorption based on 2
It was confirmed that it was -(1-propenyl)-2-cyclobentenone.

The IR chart of the obtained compound is shown in attached FIG. 2.

Example 3 In Example 1, 2-bromohexylaldehyde dimethyl acetal was used instead of 2-bromobutyraldehyde dimethylacecool, and a heating reaction was performed in the first and second half of the dehydrobromation reaction under the reaction conditions. The reaction was carried out under exactly the same reaction conditions except that the temperature was changed for 1 hour and 2 hours, respectively.

In this way, 2-(1-hexenyl)-2-cyclobentenone could be synthesized with a yield of 80%.

The NMR spectrum of this product has a methyl group of 0.9 (t),
Methylene group 1-2.66 (methylene δ, K1.33, α
, β, γ, 2.33) (m), olefin proton group H
c5.97 (d), Hb6.64 (m), He7.19
(bS), 2-(1-hexenyl)-2-
It was identified as cyclobentenone.

The IR chart of the obtained compound is shown in the attached FIG. 3.

Example 4 In Example 1, 2-bromoisobutyraldehyde dimethyl was used instead of 2-bromobutyraldehyde dimethyl acecool, and among the reaction conditions, the reaction time of the first half of the dehydrobromation reaction step was changed to 5 hours. The reaction was otherwise carried out under exactly the same reaction conditions.

In this way, 2-(1-inbutenyl)-2-cyclobentenone could be synthesized with a yield of 78%.

The NMR spectrum of this product shows a gem-dimethyl group, 1
．． 82 (S), methylene group δ2.33 (m), methylene group γ2.66 (bS), olefin proton group Ha5.
72 (bs), Hb 7.28 (bs), 2
It was confirmed that it was -(1-inbutenyl)-2-cyclobentenone.

Example 5 In Example 1, 2-bromocyclohexanone dimethyl acetal was used instead of 2-bromobutyraldehyde dimethyl acecool, and the reaction time for the first half of the dehydrobromination reaction was 1 hour, and the reaction time for the second half was 1 hour. The reaction was carried out under exactly the same reaction conditions except that the process time was changed to 1 hour.

2-(1-cyclohexenyl)-2-cyclobentenone could be synthesized with a good yield of 93%.

The NMR spectrum of this product is methylene group (bs) 1
．． 7(t), methylene group adgh 2-2.66(m)
, olefin proton, He6.75 (bs), and onfin proton Hf7.7 (t), 2-(1-
It was able to be identified as cyclohexenyl)-2-cyclobentenone.

[Brief explanation of the drawing]

Figures 1 to 3 show Examples 1 to 3 synthesized by the method of the present invention.
FIG. 2 is an infrared absorption spectrum diagram of the compound.

Claims (1)

[Claims] 1 The following formula (4) However, in the formula, R1, R2 and R3 each represent a hydrogen atom or a lower alkyl group, and R2 and R3 become -g to form a cycloalkyl group. and R4 represents a lower alkyl group, and a compound represented by the following formula (3), where R represents an alkyl group, are subjected to a condensation reaction in the presence of a Lewis acid. The following formula (1) is characterized by heating in an organic solvent in the presence of an acid and in the presence of an organic base, where R1, R2, and R3 are as described in formula (4). A method for producing 2-(1-alkenyl)-2-cyclopetenone, which has the same meaning as .