JPS6050196B2 - Method for producing 2-alkyl-4H-bilan-4-one - Google Patents

Description

[Detailed explanation of the invention] The present invention is a general formula (i), r ＾, ゜ ゜ ゜ ゜ ゜ (i) (in the formula, R ＾ represents a low alkyl group) The present invention relates to a method for producing -4-one.

In the above general formula (1), R1 is a methyl group, an ethyl group,
Represents a lower alkyl group such as a propyl group or a butyl group,
A methyl group is preferred from the viewpoint of the usefulness of the target compound, which will be described later.

2- represented by general formula (1) produced by the present invention
Alkyl-4H-pyran-4-ones are useful as intermediates in the synthesis of organic compounds that serve as hypnotics, antibacterial agents, or flavoring agents such as maltol.

Furthermore, 2-methyl? - Pyran-4-one is valuable as a solvent or absorbent for acetylene. Conventionally, the following examples are known as methods for synthesizing 2-methyl-4H-pyran-4-one among the 2-alkyl-4H-pyran-4-ones represented by the general formula (1). These methods require expensive raw materials and/or reagents or have a large number of steps, and in each method, the yield of the target 2-methyl-4H-pyran-4-one is low.

The present inventors have discovered that 2-alkyl-4 represented by general formula (1)
As a result of intensive research into the synthesis method of H-pyran-4-one, a method was discovered which allows the 2-alkyl-pyran-4-one to be obtained easily and in good yield, resulting in the present invention.

That is, the present invention provides a compound represented by the general formula (■) (wherein R1 has the same meaning as in the general formula (1), and two R2 and R3 represent the same or different lower alkyl groups). -alkyl-1,5,5
- A method for producing a 2-alkyl-decoy-pyran-4-one represented by the general formula (1), which comprises treating trialkoxy-1-penten-3-yne with an acid in the presence of water,
and 1-alkoxy 1 represented by the general formula (■) (wherein R3 has the same meaning as in the general formula (■))
-Buten-3-yne and the general formula (■) (wherein R1 has the same meaning as in the general formula (1), and three R2 have the same meaning as in the general formula (■)) The general formula (
5-alkyl-1,5,5-trialkoxy-1-penten-3-yne represented by (2) is synthesized, and then the 5-
Production of a 2-alkyl-mono-pyran-4-one represented by the general formula (1), which is characterized by treating an alkyl-1,5,5-trialkoxy-1-penten-3-yne with an acid in the presence of water. Regarding the method.

The reaction of the present invention is illustrated as follows.

(wherein R1, R2 and R3 have the above meanings)
5-alkyl-1,5,5-trialkoxy-1-penten-3-yne represented by the general formula (■) is a new compound; It can be easily obtained by heating 3-yne and an orthocarboxylic acid ester represented by the general formula (■) in the presence of a Friedel-Crafts type metal halide catalyst and reacting the resulting alcohol while distilling it off. Examples of the 1-alkoxy-1-buten-3-yne represented by the general formula (■) as a raw material include 1-methoxy-1-buten-3-yne, 1-ethoxy-1-buten-3-yne, etc., and these compounds can be easily obtained from diacetylene and alcohol (Japanese Patent Application Laid-Open No. 1001-1989)
(Refer to Publication No. 3 and Japanese Unexamined Patent Publication No. 48-10014)
. Further, specific examples of the orthocarboxylic acid ester represented by the general formula (■) include 1,1,1-trimethoxyethane,
1,1,1-triethoxyethane, 1,1,1-tri-n-butoxyethane, 1,1,1-triethoxypropane, 1,1,1-triethoxybutane, 1,1,1-
Examples include triethoxypentane, 3-methyl-1,1,1-triethoxybutane, and the like. The Friedel-Crafts type metal halide catalyst used is, for example, aluminum chloride, zinc chloride, zinc iodide, tin tetrachloride, titanium tetrachloride, ferric chloride, etc., and preferably zinc chloride. The amount of the catalyst is about 1.0 to 50% by weight, preferably 10 to 3% by weight, based on the 1-alkoxy-1-buten-3-yne represented by the general formula (■). This reaction is usually carried out under a nitrogen atmosphere at 40-200°C, preferably at 80°C.
It is carried out at a temperature of ~90°C. The obtained 5-alkyl-1,5,5-tolualkoxy 1 represented by the general formula (■)
- penten-3-yne in water or an organic solvent containing water,
By treatment with a catalytic amount of acid, the general formula (
A 2-alkyl-4H-pyran-4-one represented by 1) is obtained.

The amount of water is 5-alkyl 1,5 represented by the general formula (■)
, 5-trialkoxy-1-penten-3-yne or more. Examples of acids include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; organic sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid; formic acid, acetic acid, propionic acid, chloroacetic acid, trichloroacetic acid, and malonic acid. Aliphatic carboxylic acids such as benzoic acid, chlorobenzoic acid, nitrobenzoic acid, and aromatic carboxylic acids such as phthalic acid are used. Examples of organic solvents include alcohols, ether, dioxane, acetone, benzene, chloroform, and tetrahydrofuran (THF).
, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc. are used.

This reaction is carried out at temperatures between room temperature and 100°C. Next, the present invention will be specifically explained using examples. Example 1 32.4 g of ethyl orthoacetate and 3 g of zinc chloride were stirred at 80°C for 3 minutes under a nitrogen atmosphere, and 1-methoxy-1-buten-3-yne was added to the mixture at 15 rf! ．． After dropping 1,
Stirring was continued for 4 hours while distilling off the produced ethanol.

100 ml of benzene was added to the resulting reaction mixture, and after the solid matter was slurried, the mother liquor was distilled under reduced pressure to a concentration of 125-130'
As a fraction of C (21 mmHg), 16y of 1-mexy-5,5-diethoxy-1-hexene-3-yne having the following M translation spectrum was obtained (yield: 54%). NMR spectrum (100MHz) δ7F3l. l2(T, J=
8.0Hz) 611; 1.54 (s) 4; 3.52
(Q, J=8.0Hz) 4H; 3.64 (s) 4;
4.43 (D, J = 6.0Hz) 1H; 6.18 (D,
J=6.0Hz) 1H methanol 10T1. A few drops of concentrated sulfuric acid were added to a mixed solution of 2 ml of water and the mixture was heated to reflux, and 6 mL of a methanol solution of 1.9y of 1-methoxy-5,5-diethoxy-1-hexen-3-yne was added dropwise to the solution.

After cooling down to 3°C, the reaction solution was made neutral by adding potassium carbonate powder, the solvent was distilled off, and the residue was extracted with ethyl acetate. By distilling off ethyl acetate from the extract and performing vacuum distillation, the temperature was reduced to 75-77°C (2rT1mHg).
1.0y of 2-methyl-4H-pyran-4-one having the following NMR spectrum was obtained as a fraction (yield: 95%).
%). NMR spectrum (100MHz) δ7'3:
2.12 (s) 3H: 6.01 (D, J = 2.0H
z) 1H; 6.11 (Dd, J=6.0Hz,
J=2.0Hz) 1H; 7.55(D, J=6.0
Hz) 1H Examples 2 to 5 The respective corresponding 5-methyl-1 , 5,5-trialkoxy-1-penten-3-yne, and each of the 5-methyl-1,5
, 5-trialkoxy-1-penten-3-yne and various acids in the same manner as in Example 1 to obtain 2-methyl-4H-pyran-4-one.

Claims (1)

[Claims] 1 Represented by the general formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1, two R^2 and R^3 represent the same or different lower alkyl groups) 5-alkyl-1,5,5-trialkoxy-1-pentene-
A general formula characterized by treating 3-yne with an acid in the presence of water ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (wherein R^1 has the above meaning) 2-
A method for producing alkyl-4H-pyran-4-one. 2 General formula R^3OCH=CH-C≡CH (in the formula, R^3OCH=CH-C≡CH
3 represents a lower alkyl group) and the general formula R^1C (OR^2
)_3 (wherein R^1 and three R^2 represent the same or different lower alkyl groups) is reacted in the presence of a Friedel-Crafts type metal halide catalyst. By the general formula▲mathematical formula,
There are chemical formulas, tables, etc.▼ 5-alkyl-1,5,5-trialkoxy-1-pentene-3 represented by (in the formula, R^1, R^2 and R^3 have the above meanings) -ynthesis, and then the 5
General formula characterized by treating -alkyl-1,5,5-trialkoxy-1-penten-3-yne with acid in the presence of water▲There are mathematical formulas, chemical formulas, tables, etc.▼……(
I) A method for producing 2-alkyl-4H-pyran-4-one represented by the formula (wherein R^1 has the above meaning).