JPS61225172A - Production of 2-formylquinoxaline - Google Patents

Abstract

PURPOSE:In producing 2-formylquinoxalin-di-N-oxidodimethylacetal from benzofuroxane and pyruvaldehyde dimethylacetal, a 1-alkyl-2-pyrrolidone, etc. is used as a reaction solvent. CONSTITUTION:Benzofuroxane is reacted with pyruvaldehyde dimethylacetal in the presence of 0.5-2.5mol ammonia based on 1mol benzofuroxane by the use of a 1-alkyl-2-pyrrolidone and/or 1,3-dialkyl-2-imidazolidinone as a reaction solvent at 20-50 deg.C, to give 2-formylquinoxaline-di-N-oxidodimethylacetal. An amount of the reaction solvent used is preferably 2-10 times as much as benzofuroxane. EFFECT:The aimed substance is obtained high purity in high yield by using an easily obtainable reaction solvent. USE:A raw material for animal drugs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing 2-formylquinoxaline-di-N-oxide dimethyl acetal, comprising:
More specifically, in a method for producing 2-formylquinoxaline di-N-oxide dimethyl acetal by reacting benzofuroxane and pyruvaldehyde dimethyl acetal in the presence of ammonia, the reaction is carried out using 1-alkyl-2- pyrrolidone and/or 1゜3-sialgyl-
The present invention relates to a method for producing 2-formylquinoxaline di-N-oxide dimethyl acetal, which is characterized in that it is carried out using 2-imidazolidinone as a reaction medium. The object compound of the present invention is useful as a raw material for the veterinary drug methyl-(2-quinoha-1''xanyl-methylene)-calgycetodi-N-oxide.

According to conventional synthetic methods known in the art, at 10-30°C in dimethylformamide and/or dimethylsulfoxide medium,
Benzofuroxane, bilbaldehyde dimethyl acetal and ammonia are reacted for 20 to 25 hours to obtain 2-formylquinoxaline di-N-oxide dimethyl acetal in a yield of 72% (Japanese Patent Publication No. 56-430).

However, it cannot be said that the yield is sufficient with this method.

Problems to be Solved by the Invention The present inventor conducted various studies in order to solve these drawbacks, and as a result, the present inventors reacted benzofuroxane with bilvaldehyde dimethyl acetal and ammonia to produce 2-formylquinoxaline-di-N. - When producing oxide dimethyl acetal, if 1-alkyl-2-pyrrolidone and/or -1,3-dialkyl-2-imidazolidinone is used as the reaction medium, the yield will be good. The present invention was completed by discovering that oxide dimethyl acecool can be produced.

Structure of the Invention The reaction medium used in the present invention, ■-alkyl-2-pyrrolidone and 1,3-dialkyl-2-imidazolidinone, is specifically produced industrially and is easily available. Therefore, it is preferable.

The amount of the reaction medium to be used is not particularly limited, but it is usually used in an amount of 2 to IO times the weight of benzofuroxane.

It is preferable to use bilvaldehyde dimethyl acetal as a raw material in an amount of 1.0 times or more mole or more based on benzofuroxane. If the amount used is less than 10 times the mole, the reaction rate will be extremely slow.

Ammonia may be used in either gaseous or aqueous form, and the amount used is usually 0% relative to benzofuroxane.
．． It is preferable to use it within the range of 5 to 2.5 times the mole.

If it is less than 0.5 times the mole, the reaction rate is slow and impractical;
Further, even if 2.5 times the mole or more is used, no substantial increase in the reaction rate can be expected.

The reaction temperature is preferably 20 to 50°C; if the reaction temperature exceeds 50°C, tar-like products will increase and the purity of the product will decrease, and if the reaction temperature is below 20°C, the reaction will be delayed. Slow and impractical.

*1-Methyl-2-pyrrolidone, 1-ethyl-2-
Pyrrolidone, 1-propyl-2-pyrrolidone.

1-butyl-2-pyrrolidone, 1,3-dimethyl-2
-imidazolidinone, 1-methyl-3-dithyl-2-
imidazolidinone, 1-methyl-3-propyl-2-
Examples include imidazolidinone, among which 1-
Methyl-2-pyrrolidone and 1,3-dimethyl-2-
To carry out the invention with imidazolidinones, benzofuroxane and pyruvaldehyde dimethyl acetal are dissolved in the desired amount of reaction medium and ammonia is introduced at room temperature. After that, when the reaction is carried out at a predetermined temperature, the product 2-formylquinoxaline-
Di-N-oxide dimethyl acetal precipitates as crystals. The precipitated crystals are separated, washed with a suitable inert solvent, and then dried to isolate a highly pure product.

Effects of the Invention According to the present invention, the product 2-formylquinoxaline-di-N-oxide dimethyl acetal has a yield of 80%.
The product obtained above can be isolated by simply separating the crystals of the product precipitated in the reaction solution, and the furnace solution can be reused as the reaction medium.

Thus, the present invention provides 2-formylquinoxaline-di-N
- Provides a method for efficiently and easily producing oxide dimethyl acetal.

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto1).

Example 1 4.1N of benzofuroxane and 3.1g of bilbaldehyde dimethyl acetal were dissolved in 10y of 1-methyl-2-pyrrolidone, and 2,3% aqueous ammonia was added to the solution.
g was added dropwise at 80°C, f, m. When the reaction mixture was stirred at 40° C. for 20 hours, crystals were precipitated. The precipitated crystals were separated, washed with methanol, and dried to give yellow 2-formylquinoxaline-di-N-oxide dimethyl acetal 5,3.
An IC yield of 82% was obtained. Melting point 144-146°C.

Example 2 4.1 g of benzofuroxane and 3.9 g of bilbaldehyde dimethyl acetal were dissolved in the mother liquor of Example 1, and 1.41 g of 25% aqueous ammonia was added dropwise to the solution at 80°C. After reacting the reaction mixture at 40°C for 20 hours, the same treatment as in Example 1 was performed to obtain 2-formylquinoxaline-di-N-oxide dimethyl acetal.5. '/QC yield of 81%) was obtained.

Example 8 4.1 g of benzofuroxane and 8.9 g of pyruvaldehyde dimethyl acetal were dissolved in 6f of i,a-dimethyl-2-imidazolidinone, and 2.4 g of 25% aqueous ammonia was added to the solution at 80°C. dripped. The reaction mixture was heated to 40°C for 20 hours. 5.3 g (yield: 82%) of 2-formylquinoxaline-di-N-oxide dimethyl acetal was obtained.

(7 completed) Procedure amendment (voluntary) 1 Indication of the case 〆,, -,,t (7/and-.

Patent application 2 filed on March 29, 1985 Title of the invention 2 - Process for producing formylquinoxalines 3 Person making the amendment Relationship to the case Patent applicant address 2-7-4 Yokobori, Higashi-ku, Osaka-shi, Osaka Prefecture Amendment Column 5 for detailed description of the invention in the subject specification Contents of amendment (1) Changed "industrially" to "ni*industrially" in line 15 on page 3 of the specification
-Methyl-2-pyrrolidone, l-ethyl-2-pyrrolidone, l-propyl-2-pyrrolidone, l-butyl-2-
Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ■-Methyl-3-ethyl-2-imidazolidinone, ■
-Methyl-3-propyl-2-imidazolidinone, among others, 1-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are industrially corrected.

(2) Specification page 4, line 17 to page 5, line 4 [*1-methyl-
2-pyrrolidone, 1-ethyl-2-pyrrolidone,
l-propyl-2-pyrrolidone, 1-butyl-2-
Examples include pyrrolidone, l,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, l-methyl-3-propyl-2-imidazolidinone, among which l, -Methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone" are deleted.

that's all

Claims (1)

[Claims] In a method for producing 2-formylquinoxaline-di-N-oxide dimethyl acetal by reacting benzofuroxane and pyruvaldehyde dimethyl acetal in the presence of ammonia, the reaction is carried out using 1-alkyl-2-pyrrolidone and/or Or a method for producing 2-formylquinoxalines, which is carried out using 1,3-dialkyl-2-imidazolidinone as a reaction medium.