JPS6157819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cyclopentenolone.

More specifically, the present invention provides a novel method for producing cyclopentenolone represented by the following formula (), which is a useful intermediate for agricultural chemicals.

Allethrin (formula () below), which is known as a useful pesticide, was invented by MS Schecher in 1949 and is widely used all over the world due to its excellent insecticidal activity and low toxicity. Many synthesis methods are also known for the synthesis of the following formula ()).

On the other hand, esters of cyclopentenolone, which has a structure similar to allethrone and is represented by the above formula (), and various acids also have strong insecticidal activity similar to allethrin. It is known that the compound represented by the following formula (), which is an ester with cyclopropanecarboxylic acid, has extremely strong knockdown and lethal effects (Japanese Patent Publication No. 15843/1983).

However, there is no literature regarding the synthesis of cyclopentenolone represented by the above formula ().

The inventors of the present invention have made intensive studies on the method for producing cyclopentenolone represented by the formula (), and have found a method that can produce it very advantageously.Based on this, various studies have been carried out to complete the present invention. That is, the present invention is based on the formula () The present invention provides a novel method for producing a cyclopentenolone represented by the above formula (), which is characterized by ring-closing a γ-diketone represented by the formula (2) under alkaline conditions.

The compound represented by the formula () is a novel compound that has not been described in any literature, and can be easily synthesized, for example, by a method shown in the scheme below.

When carrying out the method of the present invention, reagents for creating alkaline conditions include alkali hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, and alkali carbonates such as sodium carbonate and potassium carbonate. is often used. In addition, the solvent used in this reaction usually includes water, methanol, ethanol, propanol, tetrahydrofuran, dioxane, dimethylformamide, dimethyl sulfoxide, benzene, toluene, xylene, hexane, chloroform, dichloromethane, etc. Of course, two or more of these are used. They may be used in combination, and when the reaction is carried out in a heterogeneous system of organic solvent and water, surfactants such as benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, trimethylstearylammonium chloride, etc. can also be used.

The reaction time is usually 15 minutes to 10 hours. The reaction temperature is not particularly limited, but it is carried out around -30°C to room temperature. Further, the alkali is preferably used in an amount of 0.5 to 2.0 times the molar amount of the compound represented by the formula ().

As described above, the present invention provides a method for easily producing cyclopentenolone represented by the formula (), which is an important intermediate for agricultural chemicals.
At present, there is no known easy and advantageous method for producing cyclopentenolone, and the role played by cyclopentenolone is extremely important.

Next, the present invention will be explained in more detail with reference to examples, but it goes without saying that the present invention is not limited to these examples.

Example NaOH aqueous solution (NaOH 1.6g, water 30ml) at -5℃
Cool to 2,5-dioxo-3-hydroxy-
8-nonine (compound of formula ()) 3.0g toluene
50 ml of the solution was added dropwise over 2 hours while stirring.

After further stirring the reaction solution at -5°C for 2 hours,
The pH was adjusted to 7 with 10% HC water, and the aqueous solution was saturated with sodium chloride and then separated. After the aqueous layer was further extracted twice with ethyl acetate, the ethyl acetate layer was combined with the previous toluene layer, and the solvent was distilled off. The remaining oil was distilled under reduced pressure to obtain 1.47 g of the target product, 2-methyl-3-2'-propynyl-cyclopent-2-en-4-one-1-ol (compound of formula ()), as a pale yellow oil.
Obtained. (Yield 55%) Boiling point 100-110℃ (0.1mmHg) Refractive index 1.5275 (23.5℃) NMR data (solvent CDC ₃ , internal standard TMS) δ value ppm δ1.94 (t, 1H), 2.18 (s, 3H), 2.1~3.0
(m, 2H), 3.05 (d, 2H), 4.67 (d, m,
1H) Reference example Add 10% aqueous sodium hydroxide solution (8.0 g of sodium hydroxide, 72 ml of water) to 24.0 g of diethyl 2-(2'-propynyl)-3-oxoglutarate under ice cooling, and then reduce the internal temperature to 30°C. I stirred it for 5 hours. below freezing,
After adjusting the pH of the reaction solution to 7.5 with 10% sulfuric acid, 60 ml of toluene was added. Under a nitrogen stream, 20g of methylglyoxal aqueous solution (40.7%) was heated to internal temperature over 2 hours.
It was added dropwise at 35°C. After that, the mixture was stirred at an internal temperature of 35°C for 15 hours. The reaction solution was separated into layers, the aqueous layer was saturated with sodium chloride, and extracted three times with ethyl acetate. The toluene layer and ethyl acetate layer were combined and the solvent was distilled off to obtain a pale yellow oil.
14.1 g of 5-dioxo-3-hydroxy-8-nonine (compound of formula ()) was obtained.

Yield 83.8% ^n23D _{1.4593 NMR data (CDC3 ,} internal standard TMS, δ value) 1.94 (1H, t), 2.20 (3H, s), 2.1-3.0
(6H, m), 4.3 (1H, t)

Claims (1)

[Claims] 1 formula It is characterized by ring-closing the γ-diketone represented by under alkaline conditions. A method for producing cyclopentenolone shown in