Method of preparation of acid, 2,2 - dimethyl - 3 - (b - fluoro - b - trifluoromethyl - vinyl) - cyclopropanecarboxylic, and its use as of the preparation of pyrethroids

摘要

A process for the preparation of 2,2-dimethyl-3-( beta -fluoro- beta -trifluoro- methyl-vinyl)-cyclopropanecarboxylic acid of the formula: IMAGE in which a halide of 2,4-dihalo- 4,5,5,5-tetrafluoropentanoic acid of the formula: IMAGE in which X, Y and Z may be the same or different and each represent a chlorine or bromine atom, is reacted with isobutene in the presence of a base and an inert solvent to yield 2-halo-2-(2'-halo- 2',3',3',3'-tetrafluoropropyl)-3,3-dimethyl- cyclobutanone of the formula: IMAGE which is heated in an inert solvent and in the presence of a quaternary ammonium salt or a tertiary aliphatic amine, to yield 2-(2'-halo- 2',3',3',3'-tetrafluoropropyl)-3,3-dimethyl- 4-halo-cyclobutanone of the formula: IMAGE which is treated with an alkaline base in an inert solvent to yield the compound of formula (I). The compound of formula (I) is a useful intermediate for the preparation of pyrethroids. Novel compounds of the formula IMAGE where R' is Cl, Br, OH or OR where R is C1-C4 alkyl are disclosed.