Process for the stereospecific preparation of (Z)-1-(2,4- dichlorophenyl)- 2-(imidazol-1-yl)-0-(2,4-dichlorobenzyl)-ethanon e oxime ether

摘要

For preparing substantially pure (Z)-1-(2,4-dichlorophenyl)-2- (imidazol-1-yl)-0-(2,4-dichlorobenzyl)-ethanon e oxime ether having the formula ##STR1## i.e. the cis-isomer of said oxime ether in a stereospecifically pure form, the pure (Z)-stereoisomer of the corresponding ethanone oxime is first converted into an alkali salt in a polar solvent, such as acetone or dimethylformamide, using an alkali in an amount somewhat less than the equimolar amount with respect to the said ethanone oxime, and is then converted to the desired ether by reacting it at a temperature not higher than 40 C. with a halogen compound capable of forming the desired ether. Isolation of the ether product is obtained as the free base or by precipitating it as an acid addition salt upon addition of a suitable organic or mineral acid, preferably nitric acid.