Novel process for preparation of 1-furenyl-2,2-dimethyl-cyclopropane

Abstract

A process for the preparation of cyclopropane carboxylic acid derivatives of the formula ##STR1## wherein Z is selected from the group consisting of --CN, --COOH and --COOR.sub.1, R.sub.1 is alkyl of 1 to 6 carbon atoms and R.sub.2 and R.sub.3 are alkyl of 1 to 4 carbon atoms or taken together with the carbon atom to which they are attached form a carbon homocycle of 3 to 6 carbon atoms comprising reacting at low temperatures in a solvent in the presence of a strong base a compound of the formula ##STR2## wherein Z has the above definitions and R is alkyl of 1 to 6 carbon atoms or together form a polymethylene of 2 to 3 carbon atoms with a sulfone of the formula ##STR3## wherein R.sub.2 and R.sub.3 have the above definitions and Y is an aromatic group followed by aqueous treatment to obtain a compound of the formula ##STR4## wherein Y, R, R.sub.2, R.sub.3 and Z have the above definitions, reacting the latter at a low temperature in a solvent with a strong base while letting the temperature rise to obtain a compound of the formula ##STR5## wherein R, R.sub.2, R.sub.3 and Z have the above definitions of the cis/trans configuration richer in the trans isomer and either reacting the latter when Z is --CN or --COOR.sub.1 with a strong base in an aqueous media followed by acidification to obtain a compound of the formula ##STR6## wherein R, R.sub.2 and R.sub.3 have the above definitions having the same configuration as the compound of formula V or reacting the compound of formula V or Va with an acid agent in an aqueous media to obtain the corresponding compound of formula I with the same configuration as the compound of formula V or Va and optionally treating the latter with a weak base at room temperature to obtain the compound of formula I with a trans configuration which are valuable intermediates for the preparation of esters of cyclopropane carboxylic acid having elevated insecticidal activity.