JPH0454653B2 - - 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 specifically, the present invention relates to a novel method for producing α,β-unsaturated carbonyl compounds, and more specifically, the present invention relates to a method for producing α,β-unsaturated carbonyl compounds by a reaction using an alkenyl silyl ether and an allyl carbonate as starting materials. Regarding the method. Unsaturated ketones such as cyclopentenone derivatives, cyclohexenone derivatives, cyclododecenone derivatives, etc. are useful chemical substances in the fields of fragrances, medicines, chemicals, etc. As a new method for synthesizing such unsaturated carbonyl compounds, a method has recently been reported in which an alkenylsilyl ether and an allyl carbonate are treated with a catalyst consisting essentially of palladium and α,ω-alkylene di(disubstituted) phosphine. (Organic Synthetic Chemistry, Vol. 41, No. 7, pp. 619-632, published in 1983). However, in this report, the ligands constituting the catalyst were limited to expensive compounds with a special structure, and it could not be said that they were necessarily satisfactory from an economic point of view. 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 in combination, leading to the completion of the present invention. Thus, the present invention is characterized in that an alkenylsilyl ether represented by the following general formula [] and an allyl carbonate ester are connected in the presence of a catalyst consisting essentially of a palladium compound and optionally a monodentate ligand. 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 and R ₄ are hydrogen or hydrocarbon residues, X is a trihydrocarbylsilyl group, and R ₁ , R ₂ , R ₃ and R ₄ are chain-like In the present invention, an alkenylsilyl ether represented by the general formula [] is used as the first starting material. In the formula, R ₁ is not only a hydrogen atom but also an alkyl group such as methyl group, ethyl group, propyl group, pentyl group, etc., and R ₂ , R ₃ or R ₄ can be bonded to form a cyclopentane ring, cyclohexane ring, cyclododecane ring, etc. Refers to an alkylene group forming a ring such as or an aryl group such as a phenyl group or trityl group, and R ₂ , R ₃ and R ₄ are hydrogen atoms or the same alkyl group, alkylene group, or aryl group as R ₁ . furthermore, X means a trihydrocarbylsilyl group. Among the above substituents, R ₁ , R ₂ , R ₃ and R ₄ may each form a ring in any combination. Specific examples of such compounds include, for example, 1-
Cyclohexenyltrimethylsilyl ether, 1
-cyclopentenyltrimethylsilyl ether,
2-Methyl-1-cyclohexenyltrimethylsilyl ether, 6-methyl-1-cyclohexenitrilemethylsilyl ether, 1-cyclododecenyltrimethylsilyl ether, 1-cyclohexenyltriethylsilyl ether, 1-cyclohexenyltripropylsilyl ether , 2-pentenyl-1-cyclohexenyl trimethylsilyl ether, 2-propyl-1-cyclohexenyl trimethylsilyl ether, 2-pentyl-1-
Cyclohexenyltrimethylsilyl ether, 2
-Pentyl-1-cyclopentenyl trimethylsilyl ether, 2-pentenyl-1-cyclopentenyl trimethylsilyl ether, 2-pentynyl-1-cyclopentenyl trimethylsilyl ether, 1-phenyl-1-putenyl trisilyl ether, 1-propenyl trimethylsilyl ether, 1-hexenyltrimethylsilyl ether,
Examples include 2-methyl-1-putenyltrimethylsilyl ether, 3-methyl-1-putenyltrimethylsilyl ether, and 3-phenyl-1-propenyltrimethylsilyl ether. These compounds can be synthesized by conventional methods; for example, 1-cyclohexenyltrimethylsilyl ether can be easily synthesized by reacting cyclohexanone and trimethylsilyl chloride in the presence of a base. can. The allyl carbonate ester used as the second starting material is a carbonate ester having at least one allyl residue, and usually has the following general formula []
This is a compound represented by (In the formula, R ₅ represents a hydrocarbon residue, R ₆ , R ₇ ,
Hydrogen in R ₈ and R ₉ represents a hydrocarbon residue. ) Specific examples of such compounds include diallyl carbonate, dicrotyl carbonate, dimethallyl carbonate, methylallyl carbonate, ethylallyl carbonate, propylallyl carbonate, butylallyl carbonate, pentylallyl carbonate, methylcrotyl carbonate, ethylmethallyl carbonate, and the like. Among these, allyl esters, crotyl esters, and methallyl esters in which R ₅ is a lower alkyl group or lower alkenyl group having 4 or less carbon atoms are preferred. 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 thereof include tris(dibenzylideneacetone)dipalladium(0), tris(tripenzylideneacetylacetone)tripalladium(0), palladium acetate, palladium propionate, and 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, etc.: triethyl arsenic, tributyl arsenic, triphenyl arsenic, etc. Arsenic-containing compounds such as: Examples include 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 becomes the main reaction, so the amount is preferably 2.5 mol or less per 1 mol of palladium compound, particularly 0.1 to 2.0 mol, more preferably 0.3 to 2.0 mol. A suitable amount is 1.5 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 easily by bringing two starting materials into contact with a catalyst. For example, the reaction formula when 1-cyclohexenyltrimethylsilyl ether and diallyl carbonate are used as starting materials is as follows. The ratio of raw materials used is 1 part alkenyl silyl ether
The amount of allyl carbonate ester is usually 0.8 to 5 moles, preferably 1 to 2 moles per mole, the reaction temperature is usually 50°C or higher, preferably 60 to 150°C, and the reaction time is usually 10 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, an easily available compound can be used as a catalyst, and the desired α,β-unsaturated carbonyl compound can be economically produced. The present invention will be explained in more detail with reference to Examples below. Example 1 2 moles of diallyl carbonate per mole of 1-cyclohexenyltrimethylsilyl ether in a container,
The mixture was charged in a ratio of 8 mol of acetonitrile and 0.05 mol of palladium acetate, stirred rapidly at room temperature, heated to the boiling point of the solvent, and reacted under reflux under an argon atmosphere for 1 hour. After the reaction was completed, the product was distilled under reduced pressure according to a conventional method, and 2-cyclohexen-1-one was obtained in a yield of 76%. In addition,
Identification of these compounds was performed 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 an equimolar amount of triphenylphosphine was used in addition to palladium acetate. As a result, the yield of 2-cyclohexen-1-one was 85%. In addition,
Almost no precipitation of palladium was observed during the reaction. Example 3 A reaction was carried out in the same manner as in Example 2 except that the compounds shown in Table 1 were used as starting materials. The results are shown in Table 1.

[Table] Example 4 A reaction was carried out according to Example 2 except that palladium acetylacetonate was used in place of palladium acetate, and almost the same results as in Example 2 were obtained. Example 5 A reaction was carried out according to Example 2 except that tris(dibenzylideneacetone)dipalladium (0) was used in place of palladium acetate, and results almost the same as in Example 2 were obtained.

Claims (1)

[Claims] 1. General formula [] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are hydrogen or hydrocarbon residues, X is a trihydrocarbylsilyl group, and R ₁ , R ₂ , R ₃ and R ₄ are chain-like and or each may form a ring in any combination) and an allyl carbonate are brought into contact with each other in the presence of a palladium compound catalyst containing no ligand. 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 and R ₄ are hydrogen or hydrocarbon residues, X is a trihydrocarbylsilyl group, and R ₁ , R ₂ , R ₃ and R ₄ are chain-like and Alkenyl silyl ether and allyl carbonate ester (which may form a ring or each may form a ring in any combination) are essentially composed of (a) a palladium compound and (b) a monodentate ligand. General formula characterized by bringing it into contact with a catalyst [] 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).