JPS584714B2 - Method for producing 3-isoxazolyl ureas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 3-isoxazolyl ureas.

The present inventors have discovered that 3-inoxazolyl ureas are useful as selective herbicides (Patent application No. 1986-1985).
No. 339).

However, the production method disclosed there requires a large number of steps because it uses as a raw material inoxazolylamine obtained by amidating inoxazolyl ester and then reacting the carbamoyl compound with hypochlorite.
Moreover, there is a drawback that the yield is not sufficient.

As a result of studies to improve the shortcomings of such known methods, the present inventors succeeded in developing a method for obtaining the desired 3-ynoxazolyl ureas all at once using 3-carbamoyl isoxazoles as raw materials. did.

The present invention is based on the general formula [wherein R is hydrogen, an alkyl group, or an aryl group;
is hydrogen, an alkyl group or an alkoxy group; R2 represents an alkyl group, an aralkyl group or an aryl group, or R1-N-R2 represents a pyrrolidino group, a piperidino group, a morpholino group or a 4-alkylpiperazino group; represents hydrogen or halogen, and R and X may be connected to form an alkylene group.

] In the production of 3-isoxazolyl ureas represented by the general formula [wherein R and X have the same meanings as above.

] Carboxamide and general formula R1-NH-R2 (■) [In the formula, R1 and R2 have the same meanings as above.

3, characterized in that the amine represented by ] is reacted in the presence of an alkali hypohalite and an alkali hydroxide.
-Regarding a method for producing isoxazolyl ureas.

To further explain the terms defined above, alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, cyclopyl, cyclopentyl, cyclohexyl, etc.; aryl groups include phenyl, tolyl, etc. , xylyl, etc.: Alkoxy groups include methoxy, ethoxy, propoxy, poxy, etc. Aralkyl groups include benzyl, phenethyl, etc. Alkylene groups include trimethylene, tetramethylene, pentamethylene, etc. Halogens include chlorine, bromine, Examples include iodine and the like.

The method of the present invention is represented by the following formula: [wherein R, R', R2 and X have the same meanings as above.

] Carboxamide (I) used as a raw material is derived from the corresponding carboxylic acid (V).

[In the formula, R3 represents an alkyl group, and R and butylamine, cyclohexylamine) and secondary amines (e.g., dimethylamine, diethylamine, digipyramine, dibutylamine, N-methylbutylamine, N-ethylphenethylamine, pyrrolidine, piperidine, morpholine, 4-methylpiperazine), etc. be done.

The present invention is carried out by reacting a carboxamide (■) with an amine (■) in the presence of an alkali hypohalite and an alkali hydroxide.

Examples of alkali hypohalites include alkali metal hypohalites (e.g., sodium hypobromite, potassium hypochlorite, sodium hypochlorite, potassium hypobromite) and alkali metal hypohalites. (For example, calcium hypochlorite, calcium hypobromite), etc.

The amine (■) may be used in an amount of 1 molar equivalent or more, preferably about 2 molar equivalents, relative to the carboxamide (■).

This reaction may be carried out in an aqueous solvent under moderate heating and, if necessary, under pressure.

Aqueous solvent means water and a mixed solvent of water and a hydrophilic organic solvent such as dimethyl sulfoxide.

The reaction temperature is usually 10-150°C, and the pressure is usually 1-150°C.
The pressure is 30 atm.

The method of the invention has the following advantages: (a) Good yield.

(b) The number of steps is short.

(c) It is easy to operate.

Examples of the method of the present invention are listed below.

Example 1 0.84 f of sodium hydroxide was dissolved in 11 ml of water, and 11.4 g of 1340% sodium hypochlorite solution was added to the solution under water cooling.
21 and 3.36f of 5-t-butyl-3-isoxazolylcarboxamide are added and the mixture is stirred for 3 hours.

The reaction solution contains a solution of 0.56S of sodium hydroxide dissolved in 3ml of water and a 40% dimethylamine aqueous solution of 4.51? and reflux for 1 hour while cooling with dry ice and acetone in a reflux condenser.

After cooling, the reaction solution was extracted with chloroform and the solvent was distilled off to obtain 317 g of crude product.

This was subjected to silica gel force column chromatography to obtain crystals of 1,1-dimethyl-3-(5-t-butyl-3-isoxazolyl) with a melting point of 119.5-120.5°C.
Urea 2.29S is obtained.

Example 2 Sodium hydroxide 0.84? was dissolved in 11 ml of water, 11.22 y of 1340% sodium hypochlorite and 3.36 g of 5-j-butyl-3-ynoxazolyl urpoxyamide were added thereto, and the mixture was stirred for 3 hours under water cooling.

A solution of 0.56 P of sodium hydroxide dissolved in 3 ml of water and 1.92 P of morpholine are added to the reaction solution, and the mixture is stirred for 1 hour.

After cooling, the reaction solution is extracted with chloroform and the solvent is distilled off to obtain 3.82 g of a crude product.

This was subjected to silica gel force column chromatography to form N-(5-t
2.11 g of -butyl-3-ynoxazolyl) morpholinoxamide are obtained.

Example 3 A reaction was carried out in the same manner as in Example 2 except that 4.84 g of KN-methylbenzylamine was used instead of morpholine to obtain 6.92 P of an oily substance.

This was subjected to silica gel force column chromatography to obtain 353 g of 1-benzyl-1-methyl-3-(5-t-butyl-3-ynoxazolyl)urea as crystals with a melting point of 107.0 to 108.0°C.

Example 4 The reaction was carried out in the same manner as in Example 1, except that methylamine was used instead of dimethylamine, and the melting point was 187.0 to 187.
．． 1-Methyl-3-(5-t-butyl-3-isoxazolyl)urea is obtained as crystals at 5°C.

Yield 68.5%. Example 5-11 Carboxamide (■) and amine (II) as raw materials
Using I), the reaction is carried out in the same manner as in Example 1 to obtain the corresponding target substance (I).

Example 12 To a mixed solution of 115.7 P of 13% sodium hypochlorite aqueous solution and 28.3 P of 48% sodium hydroxide aqueous solution, 5
-t-Butyl-3-isoxazolylcarboxamide 33.641 is added and stirred at 15-20°C for 30 minutes to form a solution.

To this in a pressurized reactor was added 234% dimethyl sulfoxide. =l
Then, 106.1 f of an 85% dimethylamine aqueous solution was quickly added, and the temperature was rapidly raised to 90° C. while stirring, and the mixture was stirred for 30 minutes.

After cooling, excess dimethylamine was distilled off and recovered, and the pH was adjusted to 2.0 with 35% hydrochloric acid.

A lot of the precipitated crystals were collected, washed with dilute sodium hydroxide and water, dried, and 1,1-dimethyl-3-(5
-t-butyl-3-ynoxazolyl)urea 37.0?
get.

Claims (1)

[Scope of Claims] 1 [In the formula, R is hydrogen, an alkyl group, or an aryl group; R1
is hydrogen, an alkyl group or an alkoxy group; R2 represents an alkyl group, an aralkyl group or an aryl group, or R1-N-R2 represents a pyrrolidino group, a piperidino group, a morpholino group or a 4-alkylpiperazino group; represents hydrogen or halogen, and R and X may be connected to form an alkylene group. ] In the production of 3-isoxazolyl ureas represented by the general formula [wherein R and X have the same meanings as above. ] and the carboxamide represented by the general formula R1-NH-R2 [wherein R1 and R2 have the same meanings as above. 3, characterized in that the amine represented by ] is reacted in the presence of an alkali hypohalite and an alkali hydroxide.
- A method for producing inoxazolyl ureas.