JPS6159298B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a δ-oxoacetal containing an ethylene double bond at the β and γ positions relative to the acetal group, and a novel δ-oxoacetal obtained by the method. It is known that orthoesters of lower alkanols, especially orthoformates, condense in the presence of Lewis acids with enol derivatives of aldehydes or ketones, such as enol ethers and dienoxysilanes. In the case of enol ethers, the reaction in the presence of Lewis acids such as BF ₃ , ZnCl ₂ and FeCl ₃ results in bis-β-acetals, which after hydrolysis are the raw materials for obtaining β-dicarbonyl compounds. [L.S. Povalov (L.
S. Povarov], Russ.Chem.Rev, Vol. 34, pp. 649-650 (1965
), Mezheritski et al., Vol. 42, pp. 396-397 (1973), F. Effenberger, Angew.Chem. International Board, Vol. 8, 295
~312 pages (1969)]. When enoxysilane and orthoformate are condensed in the presence of a large amount of titanium tetrachloride, β-oxoacetal is formed [T. Mukayama et al., Chemistry Letters, 1974,
15-16, same magazine, 1976, pp. 1033-1036].
Povalov (cited above) points out that alkoxydienes cannot react with orthoesters to form condensation products, but they readily react with acetals (especially acetals of α and β-ethylene aldehydes) in the presence of Lewis acids. , α・β-ethylene type δ-
Suitable for producing alkoxy acetals. [See SMMakin Lasyan Chemical Review, 38, pp. 237-248 (1969)]. According to the present invention, contrary to all expectations, it has been found that 1,3-dienoxysilane reacts with ortho esters. In particular, according to the invention, the formula A method for producing a β/γ-ethylene type δ-oxoacetal of the formula H-C(OR) ₃ (), wherein R and R ₃ are each alkyl having 1 to 4 carbon atoms, R is as defined above, and an orthoformic acid ester of the formula In the formula, R ₃ is as defined above, R ₆ is alkyl, cycloalkyl, phenyl, or arylalkyl having 1 to 4 carbon atoms, and n is an integer of 1 to 3. 1× expressed in moles per dienoxy group present in
-40 to 10 in the presence of a Lewis acid in an amount of from ^-4 to 0.5
A method is provided, characterized in that the reaction is carried out at a temperature of 150°C. In formulas () to (), various symbols particularly have the following meanings. R can be methyl, ethyl, n-propyl, isopropyl or n-butyl, and R ₆ is a straight-chain or branched alkyl of 1 to 4 carbon atoms, such as one of the aforementioned groups, cycloalkyl (e.g. cyclopentyl or cyclohexyl), phenyl, or arylalkyl (eg benzyl or β-phenylethyl).
Although R ₆ can have the most diverse meanings, for practical reasons it is advantageous to use dienoxysilanes of the formula ( ) in which R ₆ represents methyl, ethyl or phenyl. When n is 2 or 3, the group
R ₆ can be the same or different. R ₃ is more particularly methyl, ethyl, n-propyl, isopropyl, n-butyl or sec-
Can represent butyl. R ₃ preferably represents methyl or ethyl. In formula (), n is preferably 3. The dienoxysilane of the formula () used in the method of the present invention is a generally known substance, and has the general formula (R ₆ ) _o -Si(X) _4-o , where R ₆ and n are as defined above, X is a halogen atom (chlorine or bromine), an α/β- or β/γ-ethylene type aldehyde or ketone capable of enolizing mono-, di-, or tri-halogenosilane, zinc chloride, and a hydroacid. It can be easily produced by reacting in the presence of a receptor according to the method described in Belgian Patent No. 670769. Suitable enoxysilanes of formula () include: (3-methyl-1,3-butadienyloxy)-
tolylmethylsilane, and (3-ethyl-1.3
-butadienyloxy)-trimethylsilane. Suitable orthoformates for the present invention are preferably methyl and ethyl orthoformates, which yield β,γ-ethylene type δ-oxoacetals, which on hydrolysis give β,γ-ethylene type δ-ketaldehydes and ethylene It becomes type δ-dialdehyde. It is believed that the reaction for condensing orthoformate and dienoxysilane according to the method of the present invention can be represented by the following equation. The alkoxysilanes formed during the reaction are by-products of industrial value and can in fact be used in the synthesis of polysiloxane polymers. This material can be converted into organohalogenosilane by a conventional method, and this can be used again for the synthesis of enoxysilane raw materials. The amounts of dienoxysilane and orthoformate used to carry out the reaction can be close to stoichiometric, i.e. about 1 mole of orthoformate per dienoxy group present in the dienoxysilane, or stoichiometric. It is possible to deviate considerably from the standard, and it is possible to use an excess of either of the reactants, with an excess of orthoformate being preferred. The amount of orthoformate ester is from 1 to 5 mol, preferably from 1 to 2 mol, per dienoxy group present in the dienoxysilane. The condensation of orthoformic acid ester and dienoxysilane can be carried out in an organic solvent inert to the raw materials used, or in the absence of a solvent. In the first case the following can be used as solvents:
aliphatic hydrocarbons (e.g. hexane or heptane), cycloaliphatic hydrocarbons (e.g. cyclohexane),
aromatic hydrocarbons (e.g. benzene), ethers (e.g. ethyl ether or tetrahydrofuran), halogenated hydrocarbons (e.g. methylene chloride, chloroform, or carbon tetrachloride), nitriles (e.g. acetonitrile or propionitrile), or carboxamides (e.g. dimethylformamide, dimethylacetamide or N-methylpyrrolidone). The temperature at which the reaction is carried out can vary within a wide range depending on the raw materials used, the nature and amount of the catalyst.
The reaction is carried out at a temperature of -40 to +150°C, preferably 0 to +100°C. Temperatures from +10 to +70 °C are very suitable. The pressure can be subatmospheric, atmospheric, or superatmospheric. For example, it can be carried out in a closed vessel under the spontaneous pressure of the reaction materials. Lewis acids that can be used as catalysts include the aforementioned boron halides and their complexes with ethers, and transition metals [b to b in the periodic table,
Group Elements, Chemical Rubber Company's Handbook of Chemistry and Physics, No. 53
] can be a halide. Zinc and tin halides are particularly suitable and are preferably used. Zinc, stannous, and stannic chlorides and bromides can be used. The amount of catalyst, expressed in moles of Lewis acid per dienoxy group present in the dienoxysilane, can vary from 1 x 10 ^-4 to 0.5 mol of Lewis acid, especially zinc or tin halide, per dienoxy group. . This amount is 1× per dienoxy group
10 ⁻³ to 0.2 mol is preferred. The reaction time depends on the reaction conditions chosen and the type of reaction materials and can vary from a few minutes to a few hours. According to the present invention, there is also provided as a new compound a β/γ-ethylene type δ-oxoacetal of the formula defined above. Of particular value are compounds of the formula in which R ₃ is methyl. As an example of the ethylene type δ-oxoacetal of formula (), 5.
Mention may be made of 5-dimethoxy-3-methylpenten-2-al and 5,5-diethoxy-3-methylpenten-2-al. These compounds are useful as intermediates in organic synthesis. These compounds can be used to make ethylene di-type dialdehydes, which can be hydrogenated to the corresponding pentane glycols, which are used in the production of various condensation products such as polyurethanes and polyesters. . (U.S. Patent No. 3,894,115). Reaction with alkyl orthoformates in the presence of an acid catalyst (eg sulfonic acid) can produce the corresponding bis-acetals which are difunctional and highly active in organic synthesis. The invention is illustrated by the following examples. Example 1 22.2 g of ethyl orthoformate (1.5 x 10 ^-1 mol),
0.37 g of zinc chloride (2.76 x 10 ^-3 mol) and 50
ml of anhydrous acetonitrile under an argon atmosphere with a stirring device, condenser and dropping funnel attached.
Introduce into a 250 ml three-neck round bottom flask. The mixture was stirred and 23.4 g of 1-trimethylsilyloxy-3-methyl-1,3-butadiene (1.5
x 10 ^-1 mol) in 15 ml of dry acetonitrile is added over a period of 5 minutes. Heat the mixture to reflux at 76°C. After heating for 45 minutes, the mixture is cooled to 50° C. and distilled at a pressure of 20 mm Hg.
The uncondensed volatile products and solvent produced during this time are collected in a trap. Gas chromatography revealed the presence of 10.9 g of trimethylsilyloxyethane in the distillate and trap. Dissolve the residue in 50 ml of diethyl ether and add 25
Neutralize with ml of saturated sodium bicarbonate solution. The ether phase is separated, washed with 25 ml of distilled water and dried over potassium carbonate. After distilling off the solvent, 75~
19g of 5.5 in the fraction distilled at 80℃/0.3mmHg
The presence of -diethoxy-3-methylpenten-2-al was confirmed by infrared spectrometry, gas chromatography and NMR. When purified, 5,5-diethoxy-3-methylpenten-2-al is a pale yellow liquid with a boiling point of 73° C./0.2 mmHg and a refractive index n ²⁰ _D =1.4602. The product consists mainly of the trans isomer and a small amount of the cis isomer, and its infrared spectrum shows the following characteristic absorption bands:

[Formula] 1670-1660 cm ^-1 , -C=C- 1630 cm ^-1 , -C-O-C- 1100 and 1050 cm ^-1 Example 2 3.7 g of ethyl orthoformate (2.5 x 10 ^-2 mol),
3.9 g of 1-trimethylsilyloxy-3-methyl-1,3-butadiene (2.5 x 10 ^-2 mol) and
10ml of methylene chloride in a stream of argon,
Place in a 50 ml three-neck round bottom flask equipped with a stirrer, condenser, and dropping funnel. 8mg by syringe
of stannic chloride (3×10 ^-5 mol) is quickly added.
The mixture is stirred for 5 minutes and kept at 25°C. Neutralize the reaction mixture with 25 ml of saturated sodium bicarbonate solution. 25 ml of diethyl ether are added, then the organic phase is separated, washed with 25 ml of saturated aqueous NaCl and dried over potassium carbonate. After separating the potassium carbonate and removing the solvent at 20 mmHg, the residue was distilled to obtain a fraction of 70-90°C/0.3 mmHg. Gas chromatography revealed that this fraction contained 91% 5,5-diethoxy-3-methylpenten-2-al. Example 3 In a 250 ml round bottom three neck flask equipped with a stirrer, condenser and dropping funnel, under a stream of argon,
13.25 g of orthoformate (1.25×10 ⁻¹ mol), 0.312 g zinc chloride (2.3×10 ⁻² mol) and 40 ml of anhydrous acetonitrile are added. 19.5 g of 1-trimethylsilyloxy-3-methyl-1,3-butadiene (1.25×
10 ^-1 mol) was added over 5 minutes with stirring to form a mixture. This mixture is heated to reflux. After 1 hour and 10 minutes, it is confirmed by thin layer chromatography that all 1-trimethylsilyloxy-3-methyl-1,3-butadiene has disappeared. The reaction mixture is cooled and the acetonitrile is driven off under reduced pressure (20 mmHg). The residue is neutralized by adding 50 ml of saturated aqueous sodium bicarbonate solution and then 25 ml of diethyl ether. Separate the ether phase,
Dry over K ₂ CO ₃ and then concentrate. By distilling the residue, 5,5-dimethoxy-3-methylpentene-2- with a boiling point of 70-75℃/0.4mmHg
Obtain 12.7 g of Al. This compound is identified by gas-liquid chromatography and NMR.

Claims (1)

[Claims] 1 formula A method for producing a β/γ-ethylene type δ-oxoacetal of the formula H-C(OR) ₃ (), wherein R and R ₃ are each alkyl having 1 to 4 carbon atoms, R is as defined above, and an orthoformic acid ester of the formula In the formula, R ₃ is as defined above, R ₆ is alkyl, cycloalkyl, phenyl, or arylalkyl having 1 to 4 carbon atoms, and n is an integer of 1 to 3. 1× expressed in moles per dienoxy group present in
-40 to 10 in the presence of a Lewis acid in an amount of from ^-4 to 0.5
A method characterized by carrying out the reaction at a temperature of 150°C. 2. The method according to claim 1, wherein in formula (), n is 3 and R ₆ is a methyl, ethyl or phenyl group. 3. The method of claim 1, wherein 3 R is methyl or ethyl, R ₃ is methyl, R ₈ is methyl or ethyl, and n is 3. 4. The method according to any one of claims 1 to 3, wherein the Lewis acid used as a catalyst is a halide of a transition metal. 5. The method according to claim 4, wherein the catalyst used is a zinc or tin halide. 6. The method according to any one of claims 1 to 5, wherein the amount of orthoformate expressed in moles per dienoxy group is from 1 to 5. 7. The method according to any one of claims 1 to 6, wherein the reaction is carried out in the presence of an inert solvent. 8. The method according to claim 7, wherein the solvent used is a chlorine-containing saturated aliphatic hydrocarbon or a nitrile. 9 Reacting alkyl orthoformate with 1-trimethylsilyloxy-3-methyl-1,3-butadiene in the presence of zinc chloride or tin chloride to produce 5,5-dialkoxy-3-methylpenten-2-al A method according to claim 1. 10 formula A β/γ-ethylene type δ-oxoacetal of the formula, wherein R and R ₃ are each alkyl having 1 to 4 carbon atoms. 11 Claim 10 in which R ₃ is methyl
β/γ-ethylene type δ-oxoacetal as described in . 12. The β/γ-ethylene type δ-oxoacetal according to claim 11, wherein R is ethyl. 13. The β/γ-ethylene type δ-oxoacetal according to claim 11, wherein R is methyl.