JPH11116582A - Production of silyl enol ethers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject compounds useful as an intermediate for organic synthesis, a silylating agent or the like in the fields of organic synthesis, various surface treatments or the like in high yield by reacting a β-diketone compound with a disilazane compound in an organic nitrile compound solvent. SOLUTION: An organic nitrile compound (e.g. acetonitrile) is used as a solvent to carry out a reaction in a method for reacting a β-diketone compound represented by formula I (R<1> is a 1-10C alkyl or a 1-10C alkoxy) (e.g. acetylacetone) with a disilazane compound represented by formula II (R<2> to R<4> are each H or an 1-10C organic group) (e.g. hexamethyldisilazane) and producing silyl enol ethers represented by formula III. Thereby, the objective high- purity silyl enol ethers useful as an intermediate for organic synthesis, a silylating agent or the like in the fields of organic synthesis and various surface treatments or the like (e.g. 4-trimethylsiloxy-3-penten-2-one) are obtained in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a high-purity silyl enol ether useful as an intermediate for organic synthesis and a silylating agent in the fields of organic synthesis and various surface treatments. The present invention relates to a method for producing a possible silyl enol ether.

[0002]

BACKGROUND OF THE INVENTION 4-Trimethylsiloxy-3-penten-2-one and methyl-
Silyl enol ethers of β-diketone compounds typified by 3-trimethylsiloxy-2-butenoate are used as intermediates for organic synthesis, and especially as neutral silylating agents, in the fields of pharmaceuticals, agricultural chemical synthesis, various surface treatments, and the like. Are useful in the field of

[0003] As a method for synthesizing these silyl enol ethers, for example, the following reaction formula is used to prepare a β-diketone compound represented by the following general formula (1) and a chlorosilane compound represented by the following general formula (4). There is a method for synthesizing silyl enol ethers represented by the general formula (3).

[0004]

Embedded image (Where R ¹ is an alkyl group or an alkoxy group, R ² ,
R ³ and R ⁴ are each a hydrogen atom or an organic group having 1 to 10 carbon atoms. )

However, the above synthesis method requires a large amount of a solvent and requires the use of a base such as triethylamine. Therefore, the resulting hydrochloride of the base has to be filtered, and the process is complicated. is there. In addition, many of these hydrochlorides have sublimability, such as triethylamine hydrochloride, and are difficult to remove even by dissolution or filtration, so that salts that cannot be removed adhere to the distillation column during distillation isolation. This is a synthesis method that is not industrially suitable because it is mixed with a target substance. In particular, in the field of electronic materials and the like, materials having a low content of chlorine have been demanded, and the above synthesizing method may not be used in some cases.

Therefore, as a method of not generating a base hydrochloride, β β represented by the following general formula (1) as shown in the following reaction formula is used.
A synthesis method from a diketone compound and a disilazane compound represented by the following general formula (2) has been proposed.

[0007]

Embedded image (However, in the formula, R ¹ , R ² , R ³ , and R ⁴ are the same as above.)

However, the above-mentioned synthesis method has the following problems and is not satisfactory as a method for producing silyl enol ethers. That is, in the above method, although the productivity is greatly improved when a solvent is not used, the reaction rate is low at a low temperature, and the reaction at a high temperature is ammonia generated during the reaction. In the case of the reaction of methyldisilazane, 4-amino-3-penten-2-one (a compound represented by the following formula (5)) in which one ketone of acetylacetone is aminated, or it is further trimethylsilylated. 4-trimethylsilylamino-3-penten-2-one (a compound represented by the following formula (6)) is by-produced, and since these by-products have a boiling point close to that of the target product, it is difficult to remove them by distillation. There is a problem that the purity and yield of the target substance are likely to be reduced.

[0009] The amount of the following by-products is more remarkable as the scale becomes larger, and becomes a very serious problem in production on an industrial scale.

[0010]

Embedded image

Furthermore, when acetylacetone and hexamethyldisilazane are used, these compounds form a sublimable complex, which may adhere to the vessel walls and pipes and block.

On the other hand, as a method using a solvent, a method using dichloromethane as a solvent (Can. J. Che.
m. , 58 , 138 (1980)), a method using tetrahydrofuran as a solvent (trimethylchlorosilane catalyst)
(Zh. Anal. Khim., 40 , 2087 (19
85)), a method using tetrahydrofuran as a solvent (imidazole catalyst) (Synthesis, 722 (197)
6)) and the like are known.

However, the use of a non-polar solvent is not practical because the reaction rate is remarkably reduced, and the use of dichloromethane or tetrahydrofuran as a solvent is not practical because the reaction rate is slower than that without solvent. If the reaction is carried out for a long time to increase the yield, there is a problem that by-products similar to those when the above-mentioned solvent is not used are produced as by-products. Further, when a catalyst is added to increase the reaction rate, the reaction rate is increased, but there are problems such that a large amount of by-products are generated and the purity and yield of the target substance are greatly reduced.

The present invention has been made in view of the above circumstances, and provides a simpler and higher-purity silyl enol ether.
It is an object of the present invention to provide a method for producing silyl enol ethers which can be produced industrially advantageously in a high yield.

[0015]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have found that a β-diketone compound represented by the following general formula (1) and a When an organic nitrile compound is used as a solvent in the production of silyl enol ethers represented by the following general formula (3) by the reaction with the disilazane compound represented by (2), the reaction rate is significantly increased, and a catalyst is added. The reaction proceeds rapidly at a high reaction rate without the addition, and the by-product of near-boiling by-products can be effectively suppressed.
There is almost no formation of complexes between diketone compounds and disilazane compounds, and such complexes do not adhere to vessel walls and pipes, and therefore, silyl enol ethers can be produced in a simple process with high purity and high yield. And found that the present invention was completed.

[0016]

Embedded image (However, in the formula, R ¹ is an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and R ² , R ³ , and R ⁴ are each a hydrogen atom or an organic group having 1 to 10 carbon atoms.)

Accordingly, the present invention provides a method for reacting a β-diketone compound represented by the general formula (1) with a disilazane compound represented by the general formula (2) to produce a silyl enol represented by the general formula (3). Provided is a method for producing silyl enol ethers, which comprises using an organic nitrile compound as a solvent in the method for producing ethers.

Hereinafter, the present invention will be described in more detail. In the method for producing silyl enol ethers of the present invention, the β-diketone compound and the disilazane compound used as the starting materials are represented by the following general formulas (1) and (1), respectively. This is shown in 2).

[0019]

Embedded image (However, in the formula, R ¹ is an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and R ² , R ³ , and R ⁴ are each a hydrogen atom or an organic group having 1 to 10 carbon atoms.)

In the above formula, R ¹ is an alkyl or alkoxy group having 1 to 10 carbon atoms, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an n-butyl group, an iso-butyl group, or a methoxy group. , An ethoxy group and a propoxy group.

In the above formula, R ² , R ³ and R ⁴ are each a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, preferably an alkyl, aryl, aralkyl or alkenyl group. Valent hydrocarbon group, for example, methyl, ethyl, propyl, butyl, hexyl, cyclohexyl, octyl, phenyl, tolyl, benzyl, vinyl, allyl, propenyl, hexenyl and the like. All may be substituted by halogen atoms such as fluorine.

Examples of the β-diketone compound of the above formula (1) include acetylacetone, propionylacetone,
Acetylacetone derivatives such as butyrylacetone, isobutyrylacetone, caproylacetone, benzoylacetone, methyl acetoacetate, ethyl acetoacetate, isopropylacetoacetate, tert-butylacetoacetate, iso-pentylacetoacetate, Acetoacetic esters such as benzyl acetate, 1,3-cyclopentanedione, 1,3-cyclohexanedione, 4,4-dimethyl-1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione and the like And the like.

Specific examples of the disilazane compound of the above formula (2) include 1,1,3,3-tetramethyldisilazane, hexamethyldisilazane, 1,3-di-tert-
Butyl-1,1,3,3-tetramethyldisilazane,
1,3-di-n-hexyl-1,1,3,3-tetramethyldisilazane, 1,3-diphenyl-1,1,3,3
-Tetramethyldisilazane, 1,3-divinyl-1,
Examples thereof include 1,3,3-tetramethyldisilazane.

The ratio of the β-diketone compound of the above formula (1) to the disilazane compound of the above formula (2) is determined by the formula (1)
The theoretical amount of the disilazane compound of formula (2) is 0.5 to 10 equivalents to the β-diketone compound of formula (2), and particularly preferably 0.6 to 2 equivalents in consideration of economy and reactivity.

In the present invention, when the β-diketone compound of the above formula (1) is reacted with the disilazane compound of the above formula (2), an organic nitrile compound is used as a solvent.
Examples of the organic nitrile compound include acetonitrile, propionitrile, n-butyronitrile, iso-
Aliphatic nitrile compounds such as butyronitrile, n-valeronitrile, iso-valeronitrile, hexanenitrile, heptanenitrile, octanenitrile, nonanonitrile, and aromatic compounds such as benzonitrile, o-tolunitrile, m-tolunitrile, and p-tolunitrile Although a nitrile compound is exemplified, it is most preferable to use acetonitrile in consideration of economy, ease of handling, boiling point, and the like.

The amount of the organic nitrile compound to be used can be appropriately adjusted, but in consideration of both productivity and reactivity, 50 to 600 m / mol of β-diketone compound is used.
1, especially 100 to 300 ml are preferred.

The above reaction may be carried out in a mixed solvent system in which an organic nitrile compound is mixed with one or more other solvents at an arbitrary ratio within a range not to impair the object of the present invention.

The above reaction can be carried out by adding a disilazane compound to a mixture of an organic nitrile compound and a β-diketone compound, by adding a β-diketone compound to a mixture of an organic nitrile compound and a disilazane compound, or by using a solvent for both compounds. It can be done in any of the ways.

In the present invention, catalysts such as chlorosilanes such as trimethylchlorosilane, sulfonic acids such as dodecylbenzenesulfonic acid and salts thereof, and sulfates such as ammonium sulfate can be added to further increase the reaction rate. It is more preferable to carry out the reaction without a catalyst because problems of impurity contamination and by-product by-product are likely to occur.

The reaction temperature is desirably a temperature at which the temperature is refluxed from 10 ° C. If the reaction temperature is increased, the reaction rate is increased and the removal of ammonia out of the system is facilitated. Therefore, the reaction is more preferably performed under reflux.

In the present invention, silyl enol ethers represented by the following formula (3) can be obtained by such a reaction.

[0032]

Embedded image (However, in the formula, R ¹ , R ² , R ³ , and R ⁴ are the same as above.)

A specific example of the silyl enol ether represented by the above formula (3) is 4-dimethylsiloxy-3
-Penten-2-one, 4-trimethylsiloxy-3-
Penten-2-one, 4-tert-butyldimethylsiloxy-3-penten-2-one, 4-trimethylsiloxy-3-hexen-2-one, methyl-3-trimethylsiloxy-2-butenoate, ethyl-3- Trimethylsiloxy-2-butenoate, tert-butyl-3
-Trimethylsiloxy-2-butenoate and the like.

[0034]

According to the method for producing silyl enol ethers of the present invention, a high reaction rate and a high reaction rate can be achieved without using a catalyst, and by-products can be effectively suppressed.
Since the complex of the β-diketone compound and the disilazane compound does not adhere to the vessel wall or piping, it is industrially very advantageous.

The silyl enol ethers obtained by the method of the present invention do not contain chlorine and have high purity, so that they can be widely used as intermediates for organic synthesis, silylating agents and the like. Useful in the field.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 4-Trimethylsiloxy-3
Synthesis of -penten-2-one 364.0 g of hexamethyldisilazane in a flask equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet tube.
(2.3 mol) and 600 ml of acetonitrile,
300.3 g of acetylacetone from the dropping funnel under reflux
(3.0 mol) was added dropwise over 4 hours. After the completion of the dropwise addition of acetylacetone, the mixture was aged for 2 hours under reflux to complete the reaction. Almost no by-product was found in the reaction solution. No complex of acetylacetone and hexamethyldisilazane was formed. The resulting reaction solution was distilled under reduced pressure to give 4-trimethylsiloxy-3-penten-2-one at a pressure of 10 mmHg and a boiling point of 72 to 73 ° C.
470.7 g were obtained as a fraction. The target compound was obtained as a mixture of a cis-form and a trans-form, and had a purity of 99.7% and a yield of 91.1%.

Example 2 4-Trimethylsiloxy-3
Synthesis of -penten-2-one 300.3 g of acetylacetone (3.10 g) was added to a flask equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet tube.
0 mol) and 600 ml of acetonitrile, and 484.2 g of hexamethyldisilazane from a dropping funnel under reflux.
(3.0 mol) was added dropwise over 4 hours. At this point the reaction was complete. Almost no by-product was found in the reaction solution. No complex of acetylacetone and hexamethyldisilazane was formed.

Example 3 Synthesis of methyl-3-trimethylsiloxy-2-butenoate 61.3 g of hexamethyldisilazane was placed in a flask equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet tube.
(0.38 mol) and 100 ml of acetonitrile, and methyl refluxed 58.1 from a dropping funnel under reflux.
g (0.5 mol) was added dropwise over 3 hours. After the completion of the dropwise addition of methyl acetoacetate, the mixture was aged under reflux for 2 hours to complete the reaction. Almost no by-product was found in the reaction solution. The resulting reaction solution was distilled under reduced pressure, and methyl-3-trimethylsiloxy-2-butenoate was subjected to a pressure of 10 mmHg,
85.5 g were obtained as a fraction having a boiling point of 74 to 76 ° C. The target compound was obtained as a mixture of the cis- and trans-isomers and had a purity of
9.6% and the yield was 90.8%.

[Comparative Example 1] Synthesis of 4-trimethylsiloxy-3-penten-2-one using chlorosilane 110.1 g of acetylacetone (1.10 g) was placed in a flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer. 1 mo
l), 111.3 g (1.1 mol) of triethylamine.
l), 300 ml of toluene was added, and 108.6 g (1.0 mol) of trimethylchlorosilane was added dropwise from a dropping funnel at room temperature for 2 hours. After the completion of the dropwise addition of trimethylchlorosilane, the mixture was refluxed for 1 hour. After adding 300 ml of hexane, triethylamine hydrochloride was removed by filtration,
The filtrate was concentrated under reduced pressure using a rotary evaporator. Distillation under reduced pressure, 4-trimethylsiloxy-3-pentene-2-
90.6 g of a fraction having a pressure of 10 mmHg and a boiling point of 72 to 74 ° C. was obtained at a purity of 95.0%. Yield 52.6
%Met. At the time of distillation, triethylamine hydrochloride adhered to the distillation column and was mixed with the target product.

Comparative Example 2 Synthesis of 4-trimethylsiloxy-3-penten-2-one in tetrahydrofuran solvent Hexamethyldisilazane was placed in a flask equipped with a stirrer, refluxer, dropping funnel, thermometer and nitrogen inlet tube. 484.2g
(3.0 mol) and 600 ml of tetrahydrofuran.
3 g (3.0 mol) was added dropwise over 5 hours. After completion of the dropwise addition of acetylacetone, the mixture was aged for 3 hours under reflux. The reaction rate was 35.3%, and the reaction was very slow.

[Comparative Example 3] Synthesis of 4-trimethylsiloxy-3-penten-2-one without using a solvent A flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was charged with 300.3 g of acetylacetone (3. 0 mol)
While maintaining the temperature at 100 ° C., 484.2 g (3.0 mol) of hexamethyldisilazane was dropped from the dropping funnel over 3 hours. After the completion of the dropping of hexamethyldisilazane, the mixture was refluxed for 1 hour. The amount of by-products in the reaction solution was 2.1% for the compound (1) and 7.3% for the compound (2) based on the target product. Further, a complex of acetylacetone and hexamethyldisilazane adhered much to the vessel wall, particularly to the condenser, and there was a risk of clogging. The resulting reaction solution was distilled under reduced pressure to give 4-trimethylsiloxy-
3-penten-2-one at a pressure of 10 mmHg and a boiling point of 72
373.6 g as a fraction at ７４74 ° C., purity 91.5%. The yield was 72.3%.

After completion of the dropwise addition of acetylacetone, the mixture was aged for 3 hours under reflux. The conversion was 35.3%, and the reaction was very slow.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoichi Tonomura 28-1 Nishifukushima, larger section of Kushiro-mura, Nakakushiro-gun, Niigata Prefecture Synthetic Technology Laboratory, Shin-Etsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. A β-diketone compound represented by the following general formula (1) is reacted with a disilazane compound represented by the following general formula (2) to produce a silyl enol ether represented by the following general formula (3). A method for producing silyl enol ethers, wherein an organic nitrile compound is used as a solvent. Embedded image (However, in the formula, R ¹ is an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and R ² , R ³ , and R ⁴ are each a hydrogen atom or an organic group having 1 to 10 carbon atoms.) 2. A method for producing 4-trimethylsiloxy-3-penten-2-one by reacting acetylacetone and hexamethyldisilazane, wherein acetonitrile is used as a solvent. -A method for producing penten-2-one. 3. The reaction of methyl acetoacetate with hexamethyldisilazane to give methyl-3-trimethylsiloxy-
A method for producing 2-butenoate, wherein acetonitrile is used as a solvent.
A method for producing trimethylsiloxy-2-butenoate.