WO1991007370A1 - A METHOD FOR THE SYNTHESIS OF α, β-UNSATURATED KETONES - Google Patents

A METHOD FOR THE SYNTHESIS OF α, β-UNSATURATED KETONES Download PDF

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WO1991007370A1
WO1991007370A1 PCT/JP1990/001487 JP9001487W WO9107370A1 WO 1991007370 A1 WO1991007370 A1 WO 1991007370A1 JP 9001487 W JP9001487 W JP 9001487W WO 9107370 A1 WO9107370 A1 WO 9107370A1
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group
substituted
general formula
phenyl
lower alkyl
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PCT/JP1990/001487
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French (fr)
Inventor
Keiichi Tsukashima
Masashi Nakajima
Masayoshi Fujimaru
Kenji Suzuki
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Nippon Soda Co., Ltd.
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Priority to EP90916813A priority Critical patent/EP0454867B1/en
Priority to DE69016647T priority patent/DE69016647T2/en
Priority to KR1019910700748A priority patent/KR950003331B1/en
Priority to BR909007030A priority patent/BR9007030A/en
Publication of WO1991007370A1 publication Critical patent/WO1991007370A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C49/00—Ketones; Ketenes; Dimeric ketenes; Ketonic chelates
    • C07C49/20—Unsaturated compounds containing keto groups bound to acyclic carbon atoms
    • C07C49/203—Unsaturated compounds containing keto groups bound to acyclic carbon atoms with only carbon-to-carbon double bonds as unsaturation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C403/00—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone
    • C07C403/14—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone having side-chains substituted by doubly-bound oxygen atoms
    • C07C403/16—Derivatives of cyclohexane or of a cyclohexene or of cyclohexadiene, having a side-chain containing an acyclic unsaturated part of at least four carbon atoms, this part being directly attached to the cyclohexane or cyclohexene or cyclohexadiene rings, e.g. vitamin A, beta-carotene, beta-ionone having side-chains substituted by doubly-bound oxygen atoms not being part of —CHO groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
    • B01J31/04—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing carboxylic acids or their salts
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
    • C07C319/14—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides
    • C07C319/20—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides by reactions not involving the formation of sulfide groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
    • C07C45/67—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton
    • C07C45/68—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms
    • C07C45/72—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms by reaction of compounds containing >C = O groups with the same or other compounds containing >C = O groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
    • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
    • C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
    • C07D307/10—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
    • C07D307/12—Radicals substituted by oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D309/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings
    • C07D309/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
    • C07D309/04—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only ring hetero atom, not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to ring carbon atoms
    • C07D309/06—Radicals substituted by oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D335/00—Heterocyclic compounds containing six-membered rings having one sulfur atom as the only ring hetero atom
    • C07D335/02—Heterocyclic compounds containing six-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

Definitions

  • This invention relates to a method for the preparation of a , ⁇ -unsaturated ketones represented by general formula CI ]
  • R 1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group
  • Compound CI 9-unsaturated ketones are very useful as intermediates for pharmaceuticals and agricultural chemicals.
  • An object of this invention is to provide methods for the synthesis of a, ⁇ - unsaturated ketone with no or one hydrogen atom at the r position, with good yield, in the reaction of alkaline metal salt of acetoacetate and aldehyde.
  • the inventors earnestly studied the aforementioned reaction of alkaline metal salt of acetoacetate and aldehyde with the aim of synthesis of a, ⁇ -unsaturated ketone with no or one hydrogen atom at the 7 position, and found as the result that the low yield when such an aldehyde is reacted results from its steric hindrance and that the structure of the catalyst secondary amine and an amount of water in the system are factors to compensate for it. thus this invention has been completed.
  • the two carbons adjacent to N of secondary amine should be both methylene if the amine is cyclic and one of them be methyl if stright chain, and furthermore the amine be highly hydrophobic. Therefore, a water- soluble amine, such as piperidine, which is effective to aldehydes having two hydrogen atoms at the a position, is hardly effective to aldehydes with no or one hydrogen atom at the a position.
  • Diethylamine, dibutylamine and N-ethyl-n-laurylamine have an extremely small catalytic effect because one of the alkyl groups is not methyl.
  • An amount of water in the system is important and is required to be reduced.
  • Methods to attain it are concentration of aqueous solution of alkaline metal salt of acetoacetic acid, and/or use of acid gas or acid anhydride or concentrated mineral acid with less water content, as an acid to maintain the pH, and/or a reaction while removing water to the outside of the system by azeotropic dehydration with water-insoluble solvent.
  • hydrophobicity of catalyst secondary amine is also important: When water is large in amount, a very hydrophobic catalyst should be used, but if an amount of water is small, a relatively less hydrophobic catalyst can be used.
  • This invention is a method for the synthesis of ⁇ ,. ⁇ -unsaturated ketones which ' comprises reacting materials, in the method for the synthesis of ⁇ , ⁇ -unsaturated ketones represented by generale formula CI ]
  • R 1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group
  • ID aldehydes
  • R 2 is an alkyl group having 1 to 10 carbon atoms and of straight chain or with side chains, an alkyl group substituted by alicyclic groups or phenyl groups, an alcyclic group which may be substituted by lower alkyl groups, or a phenyl group which may be substituted by lower alkyl groups, and an R 2" substitution position is at a carbon atom other than two those adjacent to N), a cyclic secondary amine represented by general formula (2)
  • R 4 is an aliphatic group with a straight chain having 5 to 17 carbon atoms or with side chains, an alicyclic group which may be substituted by lower alkyl groups, a phenyl group which may be substituted by lower alkyl groups, or an alkyl group substituted by phenyl groups), in a ixuture solvent of water and water-insoluble organic solvent, while keeping the pH constant with acid, and by adjusting an amount of water.
  • the a, ⁇ -unsaturated ketones represented by general formula CI ] and which are the objects of synthesis in this invention are a, ⁇ -unsaturated ketones having aliphatic groups with side chains such as 5-methyl-3-hexene-2-one, 5-methyl- 3-he ⁇ tene-2-one, 5-methyl-3-octene-2-one, 5, 6-dimethyl-3-heptene-2-one, 5-methyl-3- nonene-2-one, 5-ethyl-3-nonene-2-one, 5-ethyl-3-octene-2-one, 5-methyl-3-decene-2- one, 5-methyl-3-undecene-2-one and 5-methyl-3-undecene-2-one; a, ⁇ -unsaturated ketones having alicyclic groups such as 4-cyclohexyl-3-butene-2-one, 4-(2- methylcyclohexyl)-3-butene-2-one, 4-(3-methylcyclohexyl
  • aldehyde is an aldehyde with no or one hydrogen atom at the a position includes aliphatic aldehydes branched at the a position of aldehyde such as isobutylaldehyde, 2- methylbutanal, 2-methylpentanal, 2, 3-dimethylbutanal, 2-methylhexanal, 2- ethylhexanal, 2-ethylpentanal, 2-methylheptanal and 2-methylnonal; aldehydes having alicyclic groups such as cyclohexane carbaldehyde, 2-methylcyclohexane carbaldehyde, 3-me thy 1 cyclohexane carbaldehyde and 4-methylcyclohexane carbaldehyde; heterocyclic aldehydes such as 4-tetrahydropyran carbaldehyde, 2-tetrahydrofuran carbaldeh
  • alkaline metal salt of acetoacetic acid represented by general formula CHI
  • CHI alkaline metal salt of acetoacetic acid
  • An aqueous solution of alkaline metal salt of acetoacetic acid is easily obtained by hydrolysis of diketene or acetoacetates in an aqueous solution of hydroxide alkaline solution such as sodium hydroxide or potassium hydroxide.
  • the solution can be highly concentrated under reduced pressure.
  • the catalyst secondary amines represented by general formula (1) include piperidines such as 3, 5-dimethyl ⁇ i ⁇ eridine, 3-butylpi ⁇ eridine, 4-butylpiperidine, 3- hexylpiperidine, 4-hexylpiperidine, 3-cyclohexyl ⁇ iper ⁇ dine, 4-cyclohexylpi ⁇ eridine, 4-benzyl ⁇ iperidine, 3-benzylpiperidine and 4-pheny lpiperidine; and cyclic amines such as hexamethyleneimine, heptamethyleneimine and 3, 3, 5-trimethylhexahydroazepine.
  • the two carbons adjacent to N must be both methylene.
  • the cyclic secondary amines represented by general formula (2) include cyclic amines such as 1, 2, 3, 4-tetrahydroisoquinoline, perhydroisoquinol ine, 4- methylperhydroisoquinoline and 4-ethylperhydroisoquinoline.
  • the secondary amines represented by general formula (3) include N- methylhexylamine, N-methyloctylamine, N-methyldecylamine, N-methyl-2- ethylhexylamine, N-methyloctyldecylamine, N-methyl-2-methyloctylamine, N- methylcyclohexylmethylamine and N-methylbanzylamine, being secondary amines of which one of groups bonding to N is a methyl group and the other is methylene.
  • catalyst secondary amines including 3-azabicyclo C3, 2, 2 ] nonane are used in combination of amount of water of the system:
  • a concentrated aqueous solution of alkaline metal salt of acetoacetic acid is used, relatively less hydrophobic secondary amines such as 4-methylpiperidine to very hydrophobic secondary amines such as N-methyldecylamine can be employed.
  • very hydrophobic amines such as 3-hexylpiperidine or N-methyldecylamine are selected.
  • Methods to reduce the amount of water in the system are, in addition to use of concentrated aqueous solution of alkaline metal salt of acetoacetic acid, use of acid gas such as hydrogen chloride gas, or acid anhydride such as anhydrous sulfuric acid or phosphorus pentaoxide, or concentrated acid such as concentrated sulfuric acid or 85% phosphoric acid, as an acid to control the pH, or removal of water to the outside of the system by azeotropic dehydration with water-insoluble solvent during the reaction.
  • acid gas such as hydrogen chloride gas, or acid anhydride such as anhydrous sulfuric acid or phosphorus pentaoxide
  • concentrated acid such as concentrated sulfuric acid or 85% phosphoric acid
  • Water-insoluble organic solvents used in this reaction include chlorinated hydrocarbon solvents such as dichloromethane, chloroform and dichloroethane; and aromatic solvents such as benzene, toluene and xylene.
  • acids with less water content such as concentrated sulfuric acid and 85% phosphoric acid, or acid gas such as hydrogen chloride gas, or anhydrous acids such as anhydrous sulfuric acid and phosphorus pentaoxide are preferably used, if the aqueous solution of alkaline metal salt of acetoacetic acid is around 30% in concentration. If the aqueous solution of alkaline metal salt of acetoacetic acid is 50% or more in concentration, an acid with much water content such as concentrated hydrochloric acid may be used.
  • R 1 is as defined above
  • R 1 may be byproduced in less than 10%, depending on a combination of aldehyde, catalyst and an amount of water in the system. If so, after the reaction is completed, 0.10 to 2.00 moles, to aldehyde, of mineral acid such as sulfuric acid is added to the reaction mixture to heat, then the compounds represented by general formula CIV) can be converted to the intended a , ⁇ - unsaturated ketone.
  • the aqueous layer separated from the organic layer is adjusted the pH to 13 or more with hydroxide alkali such as sodium hydroxide and extracted with water- insoluble organic solvent to recover 90% or more of the catalyst amine used.
  • the recovered can be used again.
  • the obtained aqueous solution of sodium acetoacetate was 40% in concentration and the yield was 96.5% to methyl acetoacetate.
  • 62. lg (0.20 moles) of the aqueous solution of sodium acetoacetate was placed in a reaction vessel of 200ml in inside volume, 1.13g (0.01 moles) of 3, 5-diraethylpiperidine was added and concentrated sulfuric acid was added to adjust the pH to 7.0.
  • 10ml of chloroform and 7.2g (0.10 moles) of isobuthylaldehyde to react at 40°C for 5 hours. The pH was maintained to 7.0 to 7.5 during the reaction with concentrated sulfuric acid.
  • Example 1 was repeated except using 2-ethylhexanal or cyclohexane carbaldehyde instead of isobutylaldehyde. The results are shown in Table 1.
  • Example 4
  • Example 1 or 4 was repeated using different aldehyde and catalyst secondary amine under the conditions shown in Table 1. Those for Comparative Examples 1 to 6 are shown in Table 2.
  • the aqueous solution of sodium acetoacetate which was obtained by hydrolysis of aqueous sodium hydroxide solution of methylacetoacetate according to the method of Example 1 was 32% in concentration. 93. Og (0.24 moles) of the aqueous solution was placed in a reaaction vessel of 200ml in inside volume, 2.26g (0.02 moles) of 3,5- dimethylpiperidine was added, and pH was adjusted to 7.0 with concentrated hydrochloric acid.
  • This invention is to provide methods for the synthesis of intended a , ⁇ - unsaturated ketones with no or one hydrogen atom at the 7 position with high yield under mild reaction conditions, by reacting an aqueous solution of alkaline metal salt of acetoacetic acid with aldehydes with no or one hydrogen atom at the a position in the presence of secondary amine with restricted structure as a catalyst by adjusting an amount of water in the system.
  • the invention is extremely significant in industry, particularly in manufacturing of agricultural chemicals and pharmaceuticals.

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Abstract

The present invention relates to a method for the synthesis of α, β-unsaturated ketones which comprises, in the method for the synthesis of α, β-unsaturated ketones represented by general formula (I) (where R1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group), reacting aldehydes represented by general formula (II): R1CHO (where R1 is as defined above) with alkali metal salt of acetoacetic acid represented by general formula (III) (where M+ is an alkali metal ion), in the presence as a catalyst of 3-azabicyclo[3,2,2] nonane, a cyclic secondary amine represented by general formula (1) (where n is 3 or more and up to 5, m is 1 or more and up to 10, R2 is an alkyl group having 1 to 10 carbon atoms and of straight chain or with side chains, an alkyl group substituted by alicyclic groups or phenyl groups, an alicyclic group which may be substituted by lower alkyl groups, or a phenyl group which may be substituted by lower alkyl groups, and an R2 substitution position is at a carbon atom other than the two adjacent to N), a cyclic secondary amine represented by general formula (2) (where l is 1 or more and up to 6, a ring with N is a 6-membered, 7-membered or 8-membered ring, the two neighbors of N are methylene, R3 is a lower alkyl group, its substitution position is at a carbon atom other than the two adjacent to N, and (a) is an alicyclic group or a phenyl group), or a secondary amine represented by general formula (3): CH¿3?NHCH2R?4¿ (where R4 is an aliphatic group having 5 to 17 carbon atoms and of straight chain or with side chains, an alicyclic group which may be substituted by lower alkyl groups, a phenyl group which may be substituted by lower alkyl groups, or an alkyl group substituted by phenyl groups), in a mixture solvent of water and water-insoluble organic solvent, while keeping the pH constant with mineral acid, and by adjusting the amount of water.

Description

Description
A method for the synthesis of a , β-unsaturated ketones
Technical Field:
This invention relates to a method for the preparation of a , β-unsaturated ketones represented by general formula CI ]
Figure imgf000003_0001
(where R1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group) (hereinafter referrred to as Compound CI ) ). , 9-unsaturated ketones are very useful as intermediates for pharmaceuticals and agricultural chemicals.
Background Art:
Various methods for the synthesis of unsaturated ketones using aldehyde as a starting material have been reported so far. These synthetic methods have various problems in industrial applications. For instance, in the aldol condensation of aldehyde with acetone, generally a large amount of byproducts are produced, isolation of the intended product is difficult, yield id low, and a very excessive amount of acetone is required.
In the synthetic method of condensing aldehyde and acetone using piperidine- acetic acid as a catalyst Cdescribed in such documents as Indian J. Chem. Vol 16B, 970-972 (1978)] , a large qunatity of expensive catalyst is required, and a very excessive amount of acetone is necessary.
In the synthetic method that a Wittig reagent, which is obtained from the synthesis of monochloroacetone or monobromoacetone and triphenylphosphine, with aldehyde Cdescribed in such documents as Ber. 108, 2077 (1970)] , the Wittig reagent of the material is expensive, and waste treatment is difficult. In the method that , β -unsaturated β ' -ketoester, which is obatined from the synthesis of aldehyde and tert-butyl acetoacetate, is pyrolyzed using p- toluenesulfonic acid as a catalyst at a high temperature Cdescribed in such documents as Acta Chem. Scand. , 17, 2216-220 (1963) ) , synthesis yield is low in spite of low-temperature and many-hour synthesis of a, β -unsaturated β' - ketoester.
Synthesis yield is low in spite of many-hour reaction in the synthetic method that aldehyde and actone are reacted (USP. 2,108,427).
In the method of Knoevenagel reaction of an alkaline metal salt of acetoacetic acid and aldehyde in the presence of aliphatic amine, which we applied before, (Japanese open patent No. Sho 57-4930), a, β-unsaturaated ketone is obtained with good yield if the aldehyde has two hydrogen atoms at theα position. If no or one hydrogen atom at the a position, the reaction is extremely slow and yield is low. The aqueous solution of sodium acetoacetate obtained from hydrolysis of methylacetoacetate with sodium hydroxide is around 30% in concentration. When this aqueous solution and 3-ethylthiobutanal are reacted using piperidine as a catalyst and concentrated hydrochloric acid as a pH regulating agent, the intended a, β- unsaturated. ketone is obtained with good yield of 90% or more. However, if an aldehyde branching at the a position, for instance 3-tetrahydrothiopyran carbaldehyde, is reacted under the same conditions, the yield is low.
An object of this invention is to provide methods for the synthesis of a, β- unsaturated ketone with no or one hydrogen atom at the r position, with good yield, in the reaction of alkaline metal salt of acetoacetate and aldehyde.
Disclosure of Invention:
The inventors earnestly studied the aforementioned reaction of alkaline metal salt of acetoacetate and aldehyde with the aim of synthesis of a, β -unsaturated ketone with no or one hydrogen atom at the 7 position, and found as the result that the low yield when such an aldehyde is reacted results from its steric hindrance and that the structure of the catalyst secondary amine and an amount of water in the system are factors to compensate for it. thus this invention has been completed.
In other words, as a catalyst, the two carbons adjacent to N of secondary amine should be both methylene if the amine is cyclic and one of them be methyl if stright chain, and furthermore the amine be highly hydrophobic. Therefore, a water- soluble amine, such as piperidine, which is effective to aldehydes having two hydrogen atoms at the a position, is hardly effective to aldehydes with no or one hydrogen atom at the a position.
Diethylamine, dibutylamine and N-ethyl-n-laurylamine have an extremely small catalytic effect because one of the alkyl groups is not methyl.
An amount of water in the system is important and is required to be reduced. Methods to attain it are concentration of aqueous solution of alkaline metal salt of acetoacetic acid, and/or use of acid gas or acid anhydride or concentrated mineral acid with less water content, as an acid to maintain the pH, and/or a reaction while removing water to the outside of the system by azeotropic dehydration with water-insoluble solvent.
In addition, a combination of hydrophobicity of catalyst secondary amine and amount of water in the system is also important: When water is large in amount, a very hydrophobic catalyst should be used, but if an amount of water is small, a relatively less hydrophobic catalyst can be used.
This invention is further described in detail.
This invention is a method for the synthesis ofα,. β-unsaturated ketones which' comprises reacting materials, in the method for the synthesis of α, β-unsaturated ketones represented by generale formula CI ]
Figure imgf000005_0001
(where R1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group), using aldehydes represented by general formula (ID
R'CHO CII]
(where R1 is as defined above) and alkaline metal salts of acetoacetic acid represented by general formula CI 11 D
Figure imgf000006_0001
(where M© is an alkaline metal ion) as catalysts, in the presence of 3-azabicyclo C3,2, 2 ] nonane, a cyclic secondary amine represented by general formula (1)
Figure imgf000006_0002
(where n is 3 or more and up to 5, m is 1 or more and up to 10, R2 is an alkyl group having 1 to 10 carbon atoms and of straight chain or with side chains, an alkyl group substituted by alicyclic groups or phenyl groups, an alcyclic group which may be substituted by lower alkyl groups, or a phenyl group which may be substituted by lower alkyl groups, and an R2" substitution position is at a carbon atom other than two those adjacent to N), a cyclic secondary amine represented by general formula (2)
Figure imgf000006_0003
(where, £ is 1 or more and up to 6, a ring containing N is a 6-membered, 7-membered or 8-membered ring, the two sides of N are methylene, R3 is a lower alkyl group, its substitution position is at a carbon atom other than two those adjacent to N, and /] is analicyclic group or a phenyl group), or a secondary amine represented by general formula (3) CI.3N_IC_I2R4 (3)
(where R4 is an aliphatic group with a straight chain having 5 to 17 carbon atoms or with side chains, an alicyclic group which may be substituted by lower alkyl groups, a phenyl group which may be substituted by lower alkyl groups, or an alkyl group substituted by phenyl groups), in a ixuture solvent of water and water-insoluble organic solvent, while keeping the pH constant with acid, and by adjusting an amount of water.
The a, β-unsaturated ketones represented by general formula CI ] and which are the objects of synthesis in this invention are a, β-unsaturated ketones having aliphatic groups with side chains such as 5-methyl-3-hexene-2-one, 5-methyl- 3-heρtene-2-one, 5-methyl-3-octene-2-one, 5, 6-dimethyl-3-heptene-2-one, 5-methyl-3- nonene-2-one, 5-ethyl-3-nonene-2-one, 5-ethyl-3-octene-2-one, 5-methyl-3-decene-2- one, 5-methyl-3-undecene-2-one and 5-methyl-3-undecene-2-one; a, β-unsaturated ketones having alicyclic groups such as 4-cyclohexyl-3-butene-2-one, 4-(2- methylcyclohexyl)-3-butene-2-one, 4-(3-methylcyclohexyl)-3-butene-2-one and 4-(4- methylcyclohexyl)-3-butene-2-one; a, β-unsaturated ketones having heterocyclic groups such as 4-(3-tetrahydropyranyl)-3-butene-2-one, 4-(4-tetrahydropyranyl)-3- butene-2-one, 4-(2-tetrahydrofuranyl)-3-butene-2-one and 4-(3-tetrahydrothiopyranyl) -3-butene-2-one; and a, β-unsaturated ketones having phenyl groups with substituents such as 4-phenyl-3-butene-2-one, 4-(3-methylρhenyl)-3-butene-2-one, 4- (2-methylphenyl)-3-butene-2-one, 4-(4-methylphenyl)-3-butene-2-one, 4- (4- methylthiophenyl)-3-butene-2-one and 4-(4-chlorophenyl)-3-butene-2-one.
One meterial, the aldehyde represented by general formula CII] , is an aldehyde with no or one hydrogen atom at the a position includes aliphatic aldehydes branched at the a position of aldehyde such as isobutylaldehyde, 2- methylbutanal, 2-methylpentanal, 2, 3-dimethylbutanal, 2-methylhexanal, 2- ethylhexanal, 2-ethylpentanal, 2-methylheptanal and 2-methylnonal; aldehydes having alicyclic groups such as cyclohexane carbaldehyde, 2-methylcyclohexane carbaldehyde, 3-me thy 1 cyclohexane carbaldehyde and 4-methylcyclohexane carbaldehyde; heterocyclic aldehydes such as 4-tetrahydropyran carbaldehyde, 2-tetrahydrofuran carbaldehyde, 3- tetrahydropyran carbaldehyde and 3-tetrahydrothiopyran carbaldehyde; and aromatic aldehydes such as benzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p- methylbenzaldehyde, p-methylthiobenzaldehyde and p-chlorobenzaldehyde.
The other material, alkaline metal salt of acetoacetic acid, represented by general formula CHI ] is sodium acetoacetate, potassium acetoacetate, and lithium acetoacetate. An aqueous solution of alkaline metal salt of acetoacetic acid is easily obtained by hydrolysis of diketene or acetoacetates in an aqueous solution of hydroxide alkaline solution such as sodium hydroxide or potassium hydroxide. The solution can be highly concentrated under reduced pressure.
The catalyst secondary amines represented by general formula (1) include piperidines such as 3, 5-dimethylρiρeridine, 3-butylpiρeridine, 4-butylpiperidine, 3- hexylpiperidine, 4-hexylpiperidine, 3-cyclohexylρiperϊdine, 4-cyclohexylpiρeridine, 4-benzylρiperidine, 3-benzylpiperidine and 4-pheny lpiperidine; and cyclic amines such as hexamethyleneimine, heptamethyleneimine and 3, 3, 5-trimethylhexahydroazepine. The two carbons adjacent to N must be both methylene.
The cyclic secondary amines represented by general formula (2) include cyclic amines such as 1, 2, 3, 4-tetrahydroisoquinoline, perhydroisoquinol ine, 4- methylperhydroisoquinoline and 4-ethylperhydroisoquinoline.
The secondary amines represented by general formula (3) include N- methylhexylamine, N-methyloctylamine, N-methyldecylamine, N-methyl-2- ethylhexylamine, N-methyloctyldecylamine, N-methyl-2-methyloctylamine, N- methylcyclohexylmethylamine and N-methylbanzylamine, being secondary amines of which one of groups bonding to N is a methyl group and the other is methylene.
These catalyst secondary amines including 3-azabicyclo C3, 2, 2 ] nonane are used in combination of amount of water of the system: When a concentrated aqueous solution of alkaline metal salt of acetoacetic acid is used, relatively less hydrophobic secondary amines such as 4-methylpiperidine to very hydrophobic secondary amines such as N-methyldecylamine can be employed. When the alkaline metal salt of acetoacetic acid is low in concentration, very hydrophobic amines such as 3-hexylpiperidine or N-methyldecylamine are selected.
Methods to reduce the amount of water in the system are, in addition to use of concentrated aqueous solution of alkaline metal salt of acetoacetic acid, use of acid gas such as hydrogen chloride gas, or acid anhydride such as anhydrous sulfuric acid or phosphorus pentaoxide, or concentrated acid such as concentrated sulfuric acid or 85% phosphoric acid, as an acid to control the pH, or removal of water to the outside of the system by azeotropic dehydration with water-insoluble solvent during the reaction.
Water-insoluble organic solvents used in this reaction include chlorinated hydrocarbon solvents such as dichloromethane, chloroform and dichloroethane; and aromatic solvents such as benzene, toluene and xylene.
A way of implementing the synthetic method of this invention is described in detail:
To an aqueous solution of 1 to 3 moles of alkaline metal salt of acetoacetic acid to a mole of aldehyde was added 0.01 moles or more, preferebly 0.05 to 0.20 moles, to a mole of aldehyde, of catalyst secondary amine selected by taking into account the concentrations of alkaline metal salt of acetoacetic acid and of mineral acid used to adjust the pH, and further a mineral acid is added to adjust the pH to 6.0 to 8.0.
Then 10 to 500.nl/_riole (of aldehyde) of water-insoluble organic solvent is added together with aldehyde. If no solvent is used, β-hydroxyketone represented by general formula CIV) and described later is byproduced in a large amount, though the reaction proceeds. The reaction is carried out with stirring for 1 to 8 hours at 30 to 60 °C while keeping the pH to 6.0 to 8.0 with mineral acid. As the acid, in order not to increase the amount of water in the system, acids with less water content such as concentrated sulfuric acid and 85% phosphoric acid, or acid gas such as hydrogen chloride gas, or anhydrous acids such as anhydrous sulfuric acid and phosphorus pentaoxide are preferably used, if the aqueous solution of alkaline metal salt of acetoacetic acid is around 30% in concentration. If the aqueous solution of alkaline metal salt of acetoacetic acid is 50% or more in concentration, an acid with much water content such as concentrated hydrochloric acid may be used. It is possible to use an acid with much water content such as concentrated hydrochloric acid in a manner of removing water to the outside of the system during the reaction by azeotropic dehydration with water-insoluble solvent, if the concentration of alkaline metal salt of acetoacetic acid is around 30%. After the reaction is completed, water and water-insoluble organic solvent are added, the pH is adjusted to below 2 with mineral acid, and the organic layer is separated from the aqueous layer. The organic layer is concentrated, and the obtained residue is distilled under reduced pressure to give the intendedα, β-unsaturated ketone. β -hydroxyketones represented by general formula CIV)
Figure imgf000010_0001
(where R1 is as defined above) may be byproduced in less than 10%, depending on a combination of aldehyde, catalyst and an amount of water in the system. If so, after the reaction is completed, 0.10 to 2.00 moles, to aldehyde, of mineral acid such as sulfuric acid is added to the reaction mixture to heat, then the compounds represented by general formula CIV) can be converted to the intended a , β - unsaturated ketone.
The aqueous layer separated from the organic layer is adjusted the pH to 13 or more with hydroxide alkali such as sodium hydroxide and extracted with water- insoluble organic solvent to recover 90% or more of the catalyst amine used. The recovered can be used again.
Best Mode for carrying Out the Invention:
Implementation manner of this invention is further described in detail by reference to the following examples. The range of this invention is not limited at all by the following examples. Example 1
Into a reaction vessel of 500ml in inside volume were placed 116. Og 1.0 mole) of methyl acetoacetate and 102.5g of water, to which 144.3g (1.05 moles) of 29.1% NaOH aqueous solution was dropped over an hour with stirring while cooling with water and keeping the inside temperature to below 35 °C, and after it the resulting solution was continuously stirred at 33 to 37°C for 6 hours. Then water and methanol were distilled by aspirator at 40°C under reduced pressure. Part of the content in the flask was collected to titrate for pH with 1N-HC1 standard aqueous solution. The obtained aqueous solution of sodium acetoacetate was 40% in concentration and the yield was 96.5% to methyl acetoacetate. 62. lg (0.20 moles) of the aqueous solution of sodium acetoacetate was placed in a reaction vessel of 200ml in inside volume, 1.13g (0.01 moles) of 3, 5-diraethylpiperidine was added and concentrated sulfuric acid was added to adjust the pH to 7.0. Into the resulting solution were added 10ml of chloroform and 7.2g (0.10 moles) of isobuthylaldehyde to react at 40°C for 5 hours. The pH was maintained to 7.0 to 7.5 during the reaction with concentrated sulfuric acid. After the reaction was completed, 10ml of water and 20ml of chloroform were added, the pH was adjusted to 1.5 with concentrated sulfuric acid, the organic layer was separated form the aqueous layer, and the solvent was distilled under reduced pressure. The remaining oily product was distilled under reduced pressure to give 9.9g of colorless oily product with boiling point of 61 to 64°C (28mmHg) and n *51.4439. (Crude yield: 88.7%) The obtained product was analyzed by gas chromatography to find that the intended product 5- methyl-3-hexene-2-one was 97.9% in purity. (Yield: 86.8%) 1.5% of a byproduct, 4- hydroxy-5-methylhexane-2-one, was contained.
Examples 2 and 3
Example 1 was repeated except using 2-ethylhexanal or cyclohexane carbaldehyde instead of isobutylaldehyde. The results are shown in Table 1. Example 4
46.5g (0.15 moles) of 40% aqueous solution of sodium acetoacetate synthesized under the same conditions as those of Example 1 was placed in a reaction vessel of 100ml in inside volume, 1.13g (0.Olmoles) of 3, 5-dimethylpiperidine was added, and the pH was adjusted to 7.0 with concentrated sulfuric acid. Into the resulting solution were added 10ml of chloroform and 11.4g of 4-tetrahydropyran carbaldehyde to react at 40 DC with stirring. The pH was maintained to 7.0 to 7.5 during the reaction by dropping concentrated sulfuric acid. After the reaction was completed, 10ml of water and 40ml of chloroform were added, the pH was adjusted to 1.5 with concentrated sulfuric acid, the organic layer was separated from the aqueous layer, and the solvent was distilled under reduced pressure. The remaining oily product was distilled under vacuum to give 15.Og of colorless oily product with boiling point od 91 to 95°C (0. ImmHg). (Crude yield: 97.2%) The obtained product was analyzed by gas chromatography to find that the intended product 4-(4- tetrahydropyranyl)-3-butene-2-one was 90.8% in purity. (Yield: 88.3%) 9.1% of a byproduct, 4-hydroxy-4-(4-tetrahydroρyranyl)-butane-2-one was contained.
The same reaction was repeated. After the reaction was completed, 5.9g of concentrated sulfuric acid and 30ml of chloroform were added to the reaction mixture to heat to reflux at about 60°C for 2 hours. After cooled, 20ml of water was added, the organic layer was separated and washed with water, and the solvent was distilled under reduced pressure. The remaining oily product was distilled under vacuum to give 15.4g of colorless oily product . (Crude yield: 99.6%) The obtained product was analyzed by gas chromatography to find that the intended product 4-(4- tetrahydropyranyl)-3-butene-2-one was 96.8% in purity. (Yield: 96.4%) The product, if let stand at room temperature, crystallized. The crystal had melting point of 42 to 46 °C. Examples 5 through 34, and Comparative Examples 1 through 6
Example 1 or 4 was repeated using different aldehyde and catalyst secondary amine under the conditions shown in Table 1. Those for Comparative Examples 1 to 6 are shown in Table 2.
Example 35
The aqueous solution of sodium acetoacetate which was obtained by hydrolysis of aqueous sodium hydroxide solution of methylacetoacetate according to the method of Example 1 was 32% in concentration. 93. Og (0.24 moles) of the aqueous solution was placed in a reaaction vessel of 200ml in inside volume, 2.26g (0.02 moles) of 3,5- dimethylpiperidine was added, and pH was adjusted to 7.0 with concentrated hydrochloric acid. Into the resulting solution were added 20ml of toluene and 26.Og (0.20 moles) of 3-tetrahydrothiopyrane carbaldehyde, and a mixture of toluene and water was distilled by aspirator under reduced pressure at an inside temperature of 40°C. During the distillation, the pH was adjusted to 7.0 to 7.5 with concentrated hydrochloric acid and the same amount of toluene as that of toluene distilled was continuously added into the reaction vessel so that the amount of toluene in the vessel was always about 20ml. After 5 hours, the same post treatment as that used in Examaple 4 was carried out to give the intended product of 4-(3- tetrahydrothiopyranyl)-3-butene-2-one with yield of 88.2%.
Example 36
93.Og (0.24 moles) of 32% aqueous solution of sodium acetoacetate obtained in the same manner as that used in Example 35 was placed in a reaction veseel of 200ml in inside volume, 22.6g (0.02 moles) of 3, 5-dimethylpiperidine was added, an pH was adjusted to 7.0 with concentrated hydrochloric acid. Into the rsulting solution were added 20ml of toluene and 26. Og (0.20 moles) of 3-tetrahydrothioρyran carbaldehyde to react at 40°C for 5 hours with stirring. During the reaction, hydrogen chloride gas was blown into the reaction solution in order to keep the pH in the range of 7.0 to 7.5. After the reaction was completed, the solution was treated in the same manner as that used in Example 4. 4-(3-Tetrahydrothiopyranyl)-
3-butene-2-one was obtained with yield of 89.5%. Boiling point: 107 - 108°C (0.12mmHg)
Example 37
93. Og (0.24 moles) of 32% aqueous solution of sodium acetoacetate obtained in the same manner as that used in Example 35 was placed in a reaction veseel of 200ml in inside volume, 2.26g (0.02 moles) of 3, 5-dimethylpiperidine was added, and the pH was adjusted to 7.0 with concentrated sulfuric acid. Into the resulting solution were added 20ml of toluene and 13. Og (0.10 moles) of 3-tetrahydrothiopyran carbaldehyde to react at 40°C for 5 hours with stirring. During the reaction, liquid sulfar trioxide ion was dropped during the reaction solution in order to keep the pH in the range of 7.0 to 7.5. After the reaction was completed, the same post treatment as that used in Example 4 was carried out to give 4-(3-Te trahydrothiopyranyl)-3-butene-2-one with yield of 88.9%. Boiling point: 106 - 108°C (0. lOmmHg)
Table 1
Figure imgf000015_0001
Figure imgf000016_0001
Figure imgf000017_0001
Figure imgf000018_0001
Figure imgf000018_0002
Figure imgf000019_0001
Table 2
Figure imgf000020_0001
Figure imgf000020_0002
[Effect of the Invention ]
This invention is to provide methods for the synthesis of intended a , β - unsaturated ketones with no or one hydrogen atom at the 7 position with high yield under mild reaction conditions, by reacting an aqueous solution of alkaline metal salt of acetoacetic acid with aldehydes with no or one hydrogen atom at the a position in the presence of secondary amine with restricted structure as a catalyst by adjusting an amount of water in the system. The invention is extremely significant in industry, particularly in manufacturing of agricultural chemicals and pharmaceuticals.

Claims

Claim (1) A method for the synthesis of a, β-unsaturated ketones which comprises, in the method for the synthesis of a, β-unsaturated ketones represented by generale formula
Figure imgf000022_0001
(where R1 is an aliphatic group with a side chain at the 1 position, an alicyclic group, a substituted alicyclic group, a heterocyclic group, a substituted heterocyclic group, a phenyl group or a substituted phenyl group), reacting aldehydes represented by general formula
RxCHO (where R1 is as defined above) with alkali metal salt of acetoacetic acid represented by general formula
CH,CCH,COO©M©
II
0 (where M© is an alkali metal ion), in the presence as a catalyst of 3-azabicycloC 3, 2,2 ] nonane, a cyclic secondary amine represented by general formula (1)
Figure imgf000022_0002
(where n is 3 or more and up to 5, m is 1 or more and up to 10, R2 is an alkyl group having 1 to 10 carbon atoms and of straight chain or with side chains, an alkyl group substituted by alicyclic groups or phenyl groups, an alcyclic group which may be substituted by lower alkyl groups, or a phenyl group which may be substituted by lower alkyl groups, and an R2, substitution position is at a carbon atom other than two those adjacent to N), a cyclic secondary amine represented by general formula (2)
Figure imgf000023_0001
(where, & is 1 or more and up to 6, a ring with N is a 6-membered, 7-membered or 8- membered ring, the two neighbors of N are methylene, R3 is a lower alkyl group, its substitution position is at a carbon atom other than two those adjacent to N, and k ) \ is an alicyclic group or a phenyl group), or a secondary amine represented by general formula (3)
CHgMCH^ (3) (where R4 is an aliphatic group having 5 to 17 carbon atoms and of straight chain or with side chains, an alicyclic group which may be substituted by lower alkyl groups, a phenyl group which may be substituted by lower alkyl groups, or an alkyl group substituted by phenyl groups), in a mixuture solvent of water and water-insoluble organic solvent, while keeping the pH constant with mineral acid, and by adjusting an amount of water.
PCT/JP1990/001487 1989-11-17 1990-11-15 A METHOD FOR THE SYNTHESIS OF α, β-UNSATURATED KETONES WO1991007370A1 (en)

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FR2481701A1 (en) * 1980-05-02 1981-11-06 Nippon Soda Co PROCESS FOR THE SYNTHESIS OF A, B-unsaturated CETONES
WO1986002065A1 (en) * 1984-09-27 1986-04-10 Chevron Research Company Process for preparing 1,3-cyclohexanedione derivatives and intermediates therefor

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FR2481701A1 (en) * 1980-05-02 1981-11-06 Nippon Soda Co PROCESS FOR THE SYNTHESIS OF A, B-unsaturated CETONES
WO1986002065A1 (en) * 1984-09-27 1986-04-10 Chevron Research Company Process for preparing 1,3-cyclohexanedione derivatives and intermediates therefor

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