Synthesis of asymmetrical methyl‐branched chiral ketones from the corresponding homologous wax esters. A new synthesis of the insect pheromone lardolure and of 9‐norlardolure

Abstract

AbstractThe insect pheromone (2R4R6R,8R)‐4,6,8‐trimethyl‐2‐undecyl formate (lardolure, 7c) and (2R,4R,6R,8R)‐4,6,8‐trimethyl‐2‐decyl formate (9‐norlardolure, 7b) have been synthesized from the corresponding homologous chiral methyl‐branched esters 1b and 1c, which have been obtained from the preengland wax of the domestic goose Anser a. f. domesticus. The intermediate (4R,6R,8R)‐4,6,8‐trimethyl‐2‐undecanone (4c) and (4R,6R,8R)‐4,6,8‐trimethyl‐2‐decanone (4b), the (2R)‐alcohols 5c and 5b, as well as some analogous compounds, have been characterized. 9‐Norlardolure (7b) shows a weak pheromone activity.