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

The insect pheromone (2R,4R,6R,8R)-4,6,8-trimethyl-2-undecyl formate ( lardolurel 7c) and (2R,4R,6R,8R)-4,6,8-trimethyl-2-decyl formate (9-no rlardolure, 7b) have been synthesized from the corresponding homologou s chiral methyl-branched esters 1b and 1c, which have been obtained fr om the preengland wax of the domestic goose Anser a. f. domesticus, Th e 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-Norlardol ure (7b) shows a weak pheromone activity.