Abstract: A novel process for producing a .beta.-dihalogenoethenylcyclopropane derivative of the formula, ##STR1## wherein R.sub.1 is a hydrogen atom or an alkyl group, R.sub.3 is a hydrogen atom, lower alkyl, acyl, carboxyl or alkoxycarbonyl group and R is a hydrogen atom or a lower alkyl group and each of Y.sub.1 and Y.sub.2 is a fluorine, chlorine or bromine atom respectively, which is an acidic moiety of the useful synthetic insecticides of the pyrethrin type, which process comprises a combination of a series of sequential steps starting from alkyl 3-butenyl ketone derivative of the formula (I), which may be shown according to the following reaction scheme: ##STR2## According to this process, objective compound of the formula (VI) having any cis/trans ratio can be produced by selecting the reaction condition of the Stages II-1, II-2, and IV-2.

Abstract: The present invention relates to a novel method for producing cyclopentenolone of the formula (I), ##STR1## which is a useful intermediate for producing agricultural chemicals, which comprises reacting an acetonedicarboxylic ester of the formula (VII), ##STR2## wherein R is a C.sub.1 -C.sub.6 alkyl group, with 2-propynyl chloride in the presence of magnesium alkoxide and in the presence of alkali iodide to obtain novel mono-(2-propynyl)-substituted acetonedicarboxylic ester of the formula (VI), ##STR3## wherein R is as defined above; hydrolyzing the mono-(2-propynyl)-substituted acetonedicarboxylic ester of the formula (VI) under alkaline conditions with an alkali and then reacting the hydrolyzed product with methylglyoxal of the formula, ##STR4## to obtain novel .gamma.-diketone of the formula (V), ##STR5## and ring-closing the .gamma.-diketone of the formula (V) under alkaline condition.

Abstract: A process for isomerizing 2-(.beta.,.beta.-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid represented by the formula, ##STR1## which comprises heating the acid of the formula (I) in the presence of the anhydride of the acid or a reagent producing the acid anhydride in the reaction system.The ester resulting from 2-(.beta.,.beta.-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid and, for example, 3-phenoxybenzyl alcohol is a compound which has a very wide range of insecticidal spectrum and has a very high controlling effect as a low-toxicity insecticide not only for domestic use and public health but also against insects injurious to agriculture or forestry, and in the case of the 3-phenoxybenzyl ester or 5-benzyl-3-furylmethyl ester of the 2-(.beta.,.beta.-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylic acid, the trans-isomer is lower than the cis-isomer in toxicity to warm-blooded animals.

Abstract: A new pyrethroidal pesticide containing as an active ingredient a pesticidally effective amount of novel cyclopropanecarboxylic acid esters represented by the formula, ##EQU1## wherein R is a hydrogen atom, a halogen atom, a methyl or a methoxy group, and R.sub.1 and R.sub.2 are hydrogen atom, methyl group or a halogen atom, which have a low toxicity to mammals, excellent pesticidal effect on injurious pests in cereal storage, agriculture and forestry and a wide range of uses for prevention of epidemics.

Abstract: A new cyclopropanecarboxylic acid ester represented by the formula, ##SPC1##Wherein R.sub.1 is alkyl having up to four carbon atoms, alkenyl having up to five carbon atoms, cycloalkenyl having up to six carbon atoms, alkenyl having up to five carbon atoms, benzyl, phenoxy or halogen; R.sub.2 and R.sub.3 are hydrogen, halogen or methyl; and any adjacent two of R.sub.1, R.sub.2 and R.sub.3 may combine to form polymethylene, which is useful as insecticides and acaricides having a strong insecticidal activity but a low toxicity to mammals, in agriculture, horticulture as well as public health.