Ethanol → Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, ethyl ester

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Reaction Steps

5.25 g (0.025 mol) of the lactone of 3,3-dimethyl-4-hydroxy-6,6-dichlorohex-5-enecarboxylic acid with 15 ml of thionyl chloride is held for 3 hours at 70° C. An addition of 20 ml of ethanol is then made, and the reaction mixture is allowed to stand for 14 hours at room temperature. The reaction mixture is concentrated by evaporation, and the residue is treated briefly with sodium ethylate in ethanol, as described in Example 3. After customary processing, there is obtained in 81% yield the 2-(2',2'-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid ethyl ester having a cis-trans ratio of approximately 1:4, determined according to NMR spectrum.

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