FIELD: agriculture. SUBSTANCE: method involves preparing 3-(2-chloro- 3,3,3-trifluorprop-1-ene-1-yl)-2,2-dimethyl- cyclopropanecarboxylic acid lower alkyl ester. The method comprises (a) reacting compound of formula (I): 
, wherein X is fluorine or bromine, with tri- (lower alkyl)orthoacetate containing up to four carbon atoms in each alkyl group in the presence of at least catalytic amount of acid catalyst at elevated temperature for time period sufficient to prepared compound of formula (III): 
wherein R is alkyl containing up to four carbon atoms and (b) treating the resulting compound of formula (III) by using at least one molar equivalent of base to obtain 3-(2-chloro-3,3,3-trifluoroprop-1-ene- 1-yl)-2,2-dimethylcyclopropanecarboxylic acid lower alkyl ester. The resulting products are used as intermediate compounds for preparation of insecticides. New synthesis makes it possible for the manufacturer to use flexible procedures. EFFECT: more efficient preparation method. 12 cl, 9 ex
