| 摘要 |
A process for the preparation of a dihalogenovinylcyclopropanecarboxylic acid or an ester thereof, of the formula <IMAGE> in which Hal each independently is fluorine, chlorine or bromine, R1 and R2 each independently is hydrogen or C1-4-alkyl, or R1 and R2 together with the adjacent carbon atom form a cycloaliphatic ring with up to 7 carbon atoms, and R3 is hydrogen, C1-4-alkyl or optionally substituted arylmethyl or hetero-arylmethyl, which comprises reacting a 3-chloro-2-(2',2'-dihalovinyl)propanecarboxylic acid ester of the formula <IMAGE> in which R4 is C1-4-alkyl or optionally substituted arylmethyl or hetero-arylmethyl, with a base. The propane carboxylic acid esters are new and may be formed in situ by reacting a 3-(2',2'-dihalovinyl)- gamma -butyrolactone of the formula <IMAGE> with a chlorinating agent and then with an alcohol of the formula R4-OH. The end products are insecticidally active and can also be used as intermediates for producing other insecticides.
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