JPH0454654B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing α,β-unsaturated carbonyl compounds, and more particularly, to a method for producing α,β-unsaturated carbonyl compounds by a novel reaction using allyl carbonate as a starting material. . Unsaturated ketones such as cyclopentenone derivatives, cyclohexenone derivatives, cyclododecenone derivatives, etc. are useful chemical substances in the fields of perfumery, medicine, chemicals, etc. Recently, as a new method for synthesizing such unsaturated carbonyl compounds, carbon allyl alkenyl esters are combined with palladium and α,ω-alkylene di(disubstituted)
A method of treatment with a catalyst consisting essentially of phosphine has been reported (tetrahedron letters,
Volume 24, No. 17, Nos. 1797-1800, published 1983). According to this report, the specific bidentate ligands that make up the catalyst are made essential by the reaction, and when a general-purpose ligand such as triphenylphosphine is used, It is described that the selectivity is poor. Therefore, in such conventional techniques, usable ligands are limited to expensive compounds with special structures, and the catalyst activity and reaction selectivity are not necessarily satisfactory. Therefore, the present inventors carried out intensive studies to improve the drawbacks of the conventional technology, and as a result, surprisingly, they did not use α,ω-alkylene di(disubstituted) phosphine, which was considered to be an essential catalyst component in the above report. It is effective to use palladium compounds alone in
Furthermore, the inventors have discovered that the activity and stability of the catalyst are further improved when a monodentate ligand is used within a specific range, and the present invention has been completed. Thus, according to the present invention, a carbonic acid diester represented by the following general formula [] is brought into contact with a catalyst consisting essentially of a palladium compound and optionally 1.5 mol or less of a monodentate ligand per mol of said compound. A method for producing an α,β-unsaturated carbonyl compound represented by the following general formula [] is provided. (In the above formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and
R ₈ represents hydrogen or a hydrocarbon residue, R ₁ , R ₂ ,
R ₃ and R ₄ may be chain-like or each may form a ring in any combination. ) In the present invention, an allyl type carbonate ester represented by the above general formula [] is used as a starting material. In the formula, in addition to R ₁ hydrogen atom, alkyl groups such as methyl group, ethyl group, propyl group, pentyl group, etc., or R ₂ , R ₃ or R ₄ are bonded to form a cyclopentane ring, cyclohexane ring, cyclododecane ring, etc. It refers to an alkylene group forming a ring such as R ₂ , R ₃ and R ₄ mean a hydrogen atom or an alkyl group or an alkylene group similar to R ₁ , and
R ₅ , R ₆ , R ₇ and R ₈ represent hydrogen or an alkyl group. Among the above-mentioned substituents, R ₁ , R ₂ R ₃ and R ₄ may each be formed into a ring in any combination. Specific examples of such compounds include allyl carbonate (1-cyclohexenyl) ester, allyl carbonate (1-cyclopentenyl) ester, allyl carbonate (2-methyl-1-cyclohexenyl) ester, and allyl carbonate (6-methyl) ester. -1-cyclohexenyl) ester, allyl carbonate (1-cyclododecenyl) ester, allyl carbonate (cyclohexylidene) ester, crotyl carbonate (1-cyclohexenyl) ester, -2-pentenyl carbonate (1-cyclohexenyl) ester,
-cyclohexenyl) ester, allyl carbonate (2
-propyl-1-cyclohexenyl) ester,
Allyl carbonate (2-pentyl-1-cyclohexenyl) ester, Allyl carbonate (2-pentyl-1-
cyclopentenyl) ester, allyl carbonate (2-
pentenyl-1-cyclopentenyl) ester,
Allyl carbonate (2-pentynyl-1-cyclopentenyl) ester, allyl carbonate (1-propenyl)
Examples include ester, allyl carbonate (1-hexenyl) ester, allyl carbonate (2-methyl-1-butenyl) ester, and allyl carbonate (3-methyl-1-butenyl) ester. These compounds can be synthesized according to conventional methods, for example, allyl carbonate (1-cyclohexenyl)
Taking ester as an example, it can be easily synthesized by a method of reacting cyclohexanone and allyl chloroformate. In the present invention, a palladium compound or a catalyst consisting essentially of the palladium compound and a monodentate ligand is used in the reaction. The palladium compound is a palladium salt or complex, and specific examples include tris(dibenzylideneacetone)dipalladium(0), tris(tridibezylideneacetylacetone)tripalladium(0), palladium acetate, palladium propionate, butyric acid. Palladium, palladium benzoate, palladium acetylacetonate, palladium nitrate, palladium sulfate,
Examples include palladium chloride. When using a strong inorganic acid salt among these compounds, it is desirable to coexist a base such as potassium acetate, sodium alcoholate, or tertiary amine. Among the palladium compounds, it is preferable to use a zero-valent olefin complex or a divalent organic compound. The monodentate ligand used is an electron-donating compound having a Group V element of the periodic table, that is, nitrogen, phosphorus, arsenic, or antimony, as a coordination atom, and specific examples thereof include pyridine, quinoline, trimethylamine, triethylamine, and Nitrogen-containing compounds such as butylamine; triethylphosphine, tri-n-butylphosphine, tri-n
-dodecylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-p-biphenylsphosphine, tri-o-methoxyphenylphosphine, phenyldiphenoxyphosphine, triethylphosphine, Phosphorus-containing compounds such as tri-n-butylphosphite, tri-n-hexylphosphite, triphenylphosphite, tri-o-tolylphosphite, triphenylthiophosphite; triethyl arsenic, tributyl arsenic, triphenyl arsenic, etc. Examples include arsenic-containing compounds such as; antimony-containing compounds such as tripropylantimony and triphenylantimony. Among these, nitrogen-containing compounds and phosphorus-containing compounds are preferred in terms of reaction activity, selectivity, economy, and the like. Although such a monodentate ligand is not necessarily essential as a catalyst component, by using an appropriate amount, the stability of the catalyst can be greatly improved and the amount of catalyst used can be reduced. However, if the amount used is too large, the known allylation reaction will become the main reaction, so the amount needs to be 1.5 mol or less per 1 mol of palladium compound.
In particular, it is preferably 0.1 to 1.3 mol, more preferably 0.3 to 1.2 mol. The amount of the catalyst to be used in the present invention is appropriately selected, but it is usually used in a ratio such that the palladium compound is usually 0.01 to 10 moles, preferably 0.1 to 5 moles, per 100 moles of the raw material. Although the palladium compound and the monodentate ligand may be reacted in advance, the catalyst is usually prepared by bringing both components into contact in a reaction system. The reaction of the present invention proceeds according to the following reaction formula by bringing the starting material into contact with a catalyst. The reaction temperature is usually 20°C or higher, preferably 50 to 150°C,
The reaction time is usually 5 minutes to 10 hours. In addition, a diluent can be present during the reaction, and specific examples thereof include nitriles such as acetonitrile, propionitrile, butyronitrile, and benzonitrile; dimethylformamide, diethylformamide, dimethylacetamide, dimethylpropionamide, N -Amides such as methylpyrrolidone; ethers such as tetrahydrofuran, dioxane, dibutyl ether, ethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; methyl acetate, ethyl acetate, propyl acetate, propion Esters such as ethyl acid; alcohols such as ethanol, propanol, ter-butanol, ethylene glycol, diethylene glycol monoethyl ether;
Examples include sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide; hydrocarbons such as n-hexane, cyclohexane, benzene, toluene, xylene, etc. Among them, aprotic polar solvents, especially nitriles, amides, and ethers. , ketones, and esters. These diluents typically have a starting material concentration of 1 to
It is used in a proportion of 50% by weight, and its use can improve reaction activity, selectivity, and catalyst stability. In particular, when the catalyst component does not contain a monodentate ligand, the catalyst becomes unstable, so it is appropriate to use a diluent, and among them, it is preferable to use a nitrile. After the reaction is complete, a highly purified α,β-unsaturated carbonyl compound, i.e., α,β-unsaturated ketone or α,β-unsaturated aldehyde, is obtained by separating the target product from the reaction solution using a conventional method. can get. Such unsaturated carbonyl compounds are used as intermediates for the synthesis of various useful compounds, particularly for perfumes, medicines, and the like. Thus, according to the present invention, easily available compounds can be used as catalysts, and the desired α,
β-unsaturated carbonyl compounds can be selected. The present invention will be explained in more detail with reference to Examples below. Example 1 Allyl (2-methyl-1-cyclohexenyl) carbonate ester in a container

[Formula] 20 mol of acetonitrile and palladium acetate per 1 mol
The mixture was charged in a proportion of 0.05 mol, stirred rapidly at room temperature, heated to the boiling point of the solvent, and reacted under argon atmosphere for 1 hour under reflux. After the reaction was completed, the product was distilled under reduced pressure according to a conventional method, resulting in 2-methyl-2-cyclohexen-1-one (hereinafter referred to as
MCH) was obtained in 98% yield. Note that these compounds were identified using IR, NMR, and mass spectra. Furthermore, when the conditions inside the system were observed during and after the reaction, palladium precipitation began to occur during the reaction process, and more severe precipitation was observed after the reaction was completed. Example 2 An experiment was conducted in the same manner as in Example 1 except that a predetermined amount of triphenylphosphine was used in addition to palladium acetate. The results are shown in Table 1. In any case, almost no precipitation of palladium was observed during the reaction.

[Table] From the results, it can be seen that if the amount of triphenylphosphine used is within a certain range, good results can be obtained in terms of catalyst stability and yield. Example 3 An experiment was conducted in the same manner as Experiment No. 2 of Example 2, except that the ligands shown in Table 2 were used in place of triphenylphosphine. Second result
Shown in the table. This result shows that monodentate ligands are preferable to bidentate ligands.

[Table] Example 4 An experiment was conducted in the same manner as in Experiment No. 2 of Example 2, except that 20 moles of the solvent shown in Table 3 was used in place of acetonitrile. The results are shown in Table 3.

[Table] Example 5 The reaction was carried out in the same manner as in Experiment No. 2 of Example 2, except that the compounds shown in Table 4 were used as starting materials. The results are shown in Table 4.

【table】

[Table] Example 6 The reaction was carried out according to Experiment No. 2 of Example 2, except that palladium acetylacetonate was used instead of palladium acetate, and the yield of MCH was 95%. Example 7 The reaction was carried out according to Experiment No. 2 of Example 2, except that tris(dibenzylideneacetone) dipalladium (0) was used in place of palladium acetate, and the yield of MCH was 96%. .

Claims (1)

[Claims] 1. General formula [] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈
represents a hydrogen or hydrocarbon residue, R ₁ , R ₂ ,
R ₃ and R ₄ may be chain-like or each may form a ring in any combination) is brought into contact with a palladium compound catalyst containing no ligand. The general formula [] A method for producing an α,β-unsaturated carbonyl compound represented by the formula (wherein R ₁ , R ₂ , R ₃ and R ₄ are the same as above). 2 General formula [] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈
represents a hydrogen or hydrocarbon residue, R ₁ , R ₂ ,
R ₃ and R ₄ may be chain-like or each may form a ring in any combination. (b) A general formula characterized by contacting with a catalyst consisting essentially of a monodentate ligand [] A method for producing an α,β-unsaturated carbonyl compound represented by the formula (wherein R ₁ , R ₂ , R ₃ and R ₄ are the same as above).