Method for synthesizing 3-(difluoromethyl)-1-methyl-1h-pyrazole-4-carboxylic acid and intermediates thereof

A method for synthesizing 3-(difluoromethyl)-1-methyl-1h-pyrazole-4-carboxylic acid represented by the following Formula III,

• comprising the steps of:
• (A) a diethyl ester compound represented by the following Formula IV is reacted under the action of an amine, a base and a carbonylating agent to form an acrylic diester compound represented by the following Formula I,
• wherein,
• wherein the definition of R1 is the same as above;
• (B) the above compound represented by the Formula I is reacted with a fluoride reagent, a Lewis acid and a methyl hydrazine to form a pyrazole ring-containing diester compound represented by the following Formula II,
• wherein the definition of R1 is the same as above;
• (C) a heterocyclic-containing diester compound represented by the Formula II is reacted with a base to form the 3-(difluoromethyl)-1-methyl-1h-pyrazole-4-carboxylic acid represented by the Formula III.