Vinyl-cyclopropane carboxylate(s) prodn. - by treating halo-cyclo:butanone(s) with alkoxide, useful as insecticides and acaricides

Process for preparing cyclopropane carboxylates of formula (I) comprises reacting alpha-halocyclobutanones of formulae (II) or (V) with an alkoxide MOR8, opt. in a diluent. R1-3 are H, halo, CN, opt. substd. alkyl or alkenyl, aralkyl, aryl, alkoxycarbonyl, alkylsulphonyl, arylsulphonyl, acyloxy or dialkylaminocarbonyl. R4-7 are H opt. substd. alkyl or alkenyl, halo, CN, aralkyl or aryl; or R1+R2; R2+R3; R1+R4;R4+R5;R4+7 or R5+R6 can together complete a carbocyclic ring of up to 8 ring members; R8 is the residue of an alcohol; M is equiv. of an alkali or alkaline earth metal; R12 is -CR3Hal.CHR1R2; -CHR3.C(Hal)R1R2 or -C(Hal)R3.C(Hal)R1R2).; (II) and (V) can be prepared in situ by halogenated the corresp. unhalogenated cpd. (I) are insecticides and acaricides for use in agriculture, protection of stored good and hygienic applications; or intermediates for other insecticides. Process uses readily available starting materials, is generally applicable and can provide (I) directly without isolation of intermediates. A typical cpd. is the m-phenoxybenzyl ester of 2,2-dimethyl-3-(alpha,beta,beta-trichlorovinyl)cyclopropanecarbox- ylic acid.