2-(Dihalovinyl) cyclopropane carboxylate insecticides prodn. - by reacting alkenol and orthoformate, addition of carbon tetrahalide, basic cyclisation and dehydrohalogenation

摘要

Cyclopropanecarboxylates of formula (I), are prepd. by reacting alkenols (II) with orthoesters (III) to give unsatd. esters, (IV), which, opt. after transesterification to (V), are subjected to CX4 addition to give (VI) and these dehydrohalogenated with base. (R is R1 or R8; R1 is lower alkyl; R2 and R3 are H, lower alkyl or cycloalkyl, phenyl or aralkyl; or R2 and R3 are together 2C alkylene or where one of them is not H the other can be lower alkoxycarbonyl or alkanoyl, aroyl, di (lower alkyl)amido or CN; R7 is H, lower alkyl ro cycloalkyl, phenyl or aralkyl; R8 is a gp. of formula (VII) R9 is H or CN; R10 is H, lower alkyl, phenoxy, benzyl or phenylmercapto; R11 is H or lower alkyl; R12 is O, S or vinylene; X is halo). The final stage proceeds via intermediates X, Y and Z which give (I) on further loss of HX (I) have insecticides and are prepd. more easily and in higher yields than by known processes. The prod. contain 50-90% of the more active trans isomers. Specif. claimed are (I) where X is Cl, R2 and R3 are CH3 and R is ethyl or 3-phenoxybenzyl.