JPS6234751B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula () [In the formula, R represents a lower alkyl group. ] Regarding the production method of mono-2-propynyl-substituted acetone dicarboxylic acid ester represented by 2-propynyl chloride and the general formula () [In the formula, R has the same meaning as above. ] When producing a mono-2-propynyl-substituted acetone dicarboxylic acid ester represented by the general formula () by reacting the acetone dicarboxylic acid ester represented by the following in the presence of magnesium alkoxide,
The present invention relates to a method for producing a monosubstituted acetone dicarboxylic acid ester represented by the above general formula (), characterized in that an alkali iodide is present as a catalyst. The compound represented by the general formula () can be led to cyclopentenolone (), which is an important intermediate for agricultural chemicals, for example, by the following route, and is extremely useful as an intermediate raw material for cyclopentenolone (). . Conventionally, methods for obtaining monosubstituted acetone dicarboxylic acid esters have been described, for example, in Vol. 47 of the Journal of the Japanese Society of Agricultural Chemistry.
Page 201 and Japanese Patent Publication No. 50-3298 describe methods for synthesizing monoalkyl, monoallyl, and monoaralkyl-substituted compounds. However, there is no description of the mono-2-propynyl-substituted compound according to the present invention, and according to the above literature,
Using magnesium alkoxide as a condensation base, 2-
When the reaction was attempted using propynyl bromide, the yield of the desired mono-2-propynyl substituted ester was low, and furthermore, when 2-propynyl chloride, which is industrially cheaper and easier to handle, was used, the substitution reaction did not progress. It is extremely slow, and the selectivity of the reaction and the yield of the desired mono-2-propynyl substituted ester are also extremely low. Under these circumstances, the present inventors used industrially advantageous 2-propynyl chloride to produce mono-2-propynyl-substituted acetone dicarboxylic acid ester represented by the general formula () with good selectivity and high yield. As a result of intensive studies aimed at producing the product, we found that by using an alkali iodide as a catalyst when reacting 2-propynyl chloride and acetone dicarboxylic acid ester represented by the general formula () using magnesium alkoxide as a condensation base. , the reaction proceeds more smoothly, the yield is improved, and the selectivity of the monosubstituted product is improved compared to when no alkali iodide is used, and even when 2-propynyl bromide is used, It was discovered that the reaction was greatly improved, and various studies were carried out to complete the present invention. It is generally known that various mono-, di-, tri-, and tetra-substituted products are produced during the substitution reaction of acetone dicarboxylic acid esters, and improving the selectivity of mono-substituted products is an extremely important issue. In other words, if the raw materials and byproducts in the product are unrelated to the subsequent reaction, impurities in the crude product will not be a major problem, but impurities that may be generated as in the reaction of the present invention If the components also have similar properties, each component exhibits similar behavior in the subsequent reaction, resulting in a decrease in the purity and yield of the desired product. In order to avoid this damage, it is necessary to use highly pure raw materials for the reaction in the next step, but the selectivity of the reaction itself is low and the raw materials and by-products are chemically and physically different from the target product. It is extremely difficult to separate systems that are very similar, and even if some sort of separation method were available, it would be extremely complicated and the amount of the target product obtained would be greatly reduced. Therefore, if the selectivity for producing the target product could be increased to the extent that no special purification operation is required, it would not only simplify the separation operation but also greatly improve economic efficiency. From this point of view, the method of the present invention has extremely great significance. Furthermore, it has been known that when performing a substitution reaction using a reactive organic chloride, the reactivity of the chloride can be increased by using sodium iodide as a catalyst. However, the catalyst in this case is used primarily to increase the reaction rate, as can be seen on page 1088 of "Reagents for Organic Synthesis", and is used for selectively monosubstituted products as in the present invention. There is no knowledge that it promotes production and improves yield. In carrying out the present invention, the reaction temperature can generally be in the range from 0°C to the boiling point of the solvent used, but preferably in the range from room temperature to the boiling point of the solvent. Examples of the alkali iodide used include potassium iodide, sodium iodide, and lithium iodide, with lithium iodide being particularly preferred. The amount thereof is preferably in the range of 5 mol % to 20 mol % based on the raw material acetone dicarboxylic acid ester. It goes without saying that this concept also includes alkali iodides that are produced and act within the system during the actual reaction. As a solvent, the same alkanol as that constituting the magnesium alkoxide used is generally used, but an inert organic solvent may also be added. The amount of magnesium alkoxide is 1 per acetone dicarboxylic acid ester as the raw material.
A range of mol to 3 mol is preferred. The present invention will be explained in more detail with reference to the following examples, but of course the present invention is not limited to these examples in any way. Example 1 5.2 g of magnesium (1.5 times the mole (based on methyl acetone dicarboxylate)) was reacted with 150 ml of methanol in the presence of a catalytic amount of iodine, and 25 g of methyl acetone dicarboxylate was added thereto and stirred for 1.5 hours.
1.9 g of lithium iodide (0.1 times mole (to methyl acetone dicarboxylate)) and 2-propynyl chloride
11.24 g (1.05 times the mole (based on methyl acetone dicarboxylate)) was added and reacted at 60°C for 4 hours. Next, after distilling off most of the methanol, ice, dilute hydrochloric acid, ethyl acetate, and salt were added to extract the product. The extract was dried over magnesium sulfate and then distilled to a boiling point of 90 to 101.
26.1 g of a fraction of °C/0.2 mmHg was obtained. As a result of analyzing this by gas chromatography, [raw material:
Mono-substituted product: Di-substituted product: Other = 6.0: 83.0:
8.0:3.0], and the yield for the monosubstituted product is
It was 71.0%. Examples 2-3 An alkylation reaction was carried out in exactly the same manner as in Example 1 except for the type of catalyst and reaction time, and the following results were obtained.

[Table] Reference Example 1 The following results were obtained in exactly the same manner as in Example 1 except that no catalyst was used and the reaction time was changed.

[Table] Reference Example 2 Magnesium ethoxide prepared from 1.5 times the mole (to ethyl acetone dicarboxylate) of magnesium according to Example 1 was mixed with ethyl acetone dicarboxylate to 1.05 times the mole (to ethyl acetone dicarboxylate) in ethanol. 2-propynyl chloride was reacted at 78°C for 8.5 hours, and then treated in the same manner as in Example 1 to obtain the following results.

【table】

Claims (1)

[Claims] 1 2-propynyl chloride and general formula [In the formula, R represents a lower alkyl group. ] by reacting with acetone dicarboxylic acid ester shown in the presence of magnesium alkoxide,
general formula [In the formula, R has the same meaning as above. ] A method for producing a monosubstituted acetone dicarboxylic acid ester represented by the above general formula, characterized in that an alkali iodide is present as a catalyst when producing the monosubstituted acetone dicarboxylic acid ester represented by the formula. 2. The manufacturing method according to claim 1, characterized in that lithium iodide is used as the alkali iodide.