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Method for the preparation of 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid

IP.com Disclosure Number: IPCOM000248979D
Publication Date: 2017-Jan-25

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention relates to method for the preparation of 3-fluoroalkyl-1—methylpyrazol-4- carboxylic acid, wherein it comprises the following steps: step 1, fluoroacetyl fluoride derivative shown in Formula I undergoes condensation with dimethylamino vinyl methyl ketone, as a result, 3-dimethylamino methylene-fluoro-2,4-pentanedione derivative shown in Formula II is formed; step 2, ring closing reaction takes place between said 3-dimethylamino methylene-fluoro-2,4-pentanedione shown in Formula II and methylhydrazine, in this way, 3-fluoroalkyl-1-methyl-4-acetyl pyrazol derivative shown in Formula III is obtained; step 3, the said 3-fluoroalkyl-1-methyl-4-acetyl pyrazol derivative shown in Formula III is oxidized in the presence of alkali, and then acidified, in this way, 3-fluoroalkyl-1-methylpyrazol-4- carboxylic acid shown in Formula IV is formed. Preparing method of present invention, wherein the required preparing route is simple, the raw material cost is low, the resulting yield of each step is high, and it is suitable for industrialization.

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1

Abstraction of Specification

METHOD FOR THE PREPARATION OF 3-FLUOROALKYL-1-METHYLPYRAZOL-4- CARBOXYLIC ACID

5

The present invention relates to method for the preparation of 3-fluoroalkyl-1—methylpyrazol-4- carboxylic acid, wherein it comprises the following steps: step 1, fluoroacetyl fluoride derivative shown in Formula I undergoes condensation with dimethylamino vinyl methyl ketone, as a result, 3- dimethylamino methylene-fluoro-2,4-pentanedione derivative shown in Formula II is formed; step 2, ring closing reaction takes place between said 3-dimethylamino methylene-fluoro-2,4-pentanedione 10 shown in Formula II and methylhydrazine, in this way, 3-fluoroalkyl-1-methyl-4-acetyl pyrazol derivative shown in Formula III is obtained; step 3, the said 3-fluoroalkyl-1-methyl-4-acetyl pyrazol derivative shown in Formula III is oxidized in the presence of alkali, and then acidified, in this way, 3- fluoroalkyl-1-methylpyrazol-4-carboxylic acid shown in Formula IV is formed. Preparing method of present invention, wherein the required preparing route is simple, the raw material cost is low, the 15 resulting yield of each step is high, and it is suitable for industrialization.

2

Claims

1. Method for the preparation of 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid, wherein it comprises the following steps: step 1, fluoroacetyl fluoride derivative shown in Formula I undergoes condensation with dimethyl 5 amino vinyl methyl ketone, as a result, 3-dimethylamino methylene-1, 1-difluoro-2, 4-pentanedione derivative shown in Formula II is formed:

wherein, R1 is hydrogen, fluorine or chlorine atom; R2 is fluorine or chlorine atom; 10 step 2, ring closing reaction takes place between said 3-dimethylamino methylene-1, 1-difluoro-2, 4- pentanedione shown in Formula II and methylhydrazine, in this way, 3-fluoroalkyl-1-methyl-4- acetyl pyrazol derivative shown in Formula III is obtained;

15 step 3, the said 3-fluoroalkyl-1-methyl-4-acetyl pyrazol derivative shown in Formula III is oxidized in the presence of alkali, and then acidified, in this way, 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid shown in Formula IV is formed. 20

3

Claims

2. Method for the preparation of 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid of Claim 1, wherein

in step 1, a gas of the said fluoro acetyl derivative of Formula I is directly introduced to a 5 dichloromethane solution containing dimethyl amino vinyl methyl ketone, and the reaction temperature is -5~0 ℃.

3. Method for the preparation of 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid of Claim 1, wherein in step 2, the reaction temperature is -40~0 ℃, the reaction time is 1~8h, and the molar ratio between said methylhydrazine and 3-dimethylamino methylene-fluoro-2,4-pentanedione of Formula 10 II is 1.1: 1~1.5: 1.

4. Method for the preparation of 3-fluoroalkyl-1-methylpyrazol-4-carboxylic acid of Claim 3, wherein the said reaction temperature of said step 2 is -25~20 ℃, and the reaction time is 1~2h.

5. Method for the prepara...