3-[2-chloro-2-(4-chlorophenyl)ethenyl]-2，2-dimethyl cyclopropane carboxylic acid

The preparation method is to react p-chlorobenzoyl chloride and methyl bentinate in the presence of SnCl4 to obtain 3, 3-dimethyl-4-p-chlorophenacyl butyrolactone, which is then reacted with a halogenating agent in methanol The action of PCl5 generates 3, 3-dimethyl-4, 6-dichloro-6-p-chlorophenylhexene [5] methyl ester, which is dehydrochlorinated and cyclized under the action of sodium alkoxide to obtain 3-[2- Chloro-2-(4-chlorophenyl)vinyl]-2, 2-dimethylcyclopropanecarboxylic acid methyl ester is further saponified and acidified to obtain the corresponding cyclopropanecarboxylic acid.

3-[2-chloro-2-(4-chlorophenyl)vinyl]-2,2-dimethylcyclopropanecarboxylic acid is abbreviated as cypermethrin, which is the intermediate of flufenthrin.