Process for the preparation of boll weevil sex pheromone components

摘要

A new intermediate of formula I ##STR1## in which X is chlorine, bromine or hydrogen and Y is a free or protected --CHO group, which is used in the manufacture of boll weevil sex pheromone components of formula II ##STR2## in which Z is --CHO or --CH.sub.2 OH, by catalytic hydrogenation, optionally with protection of the formyl group of II by acetalisation. Compound II is prepared by formylation of isophorone directly or after reduction and dehydration.