Abstract Ethyl and methyl trans-2, cis-6-dodecadienoate, two Bartlett pear constituents, have been prepared by a novel two-step synthesis: 1, 6-addition of lithium di-cis-1- heptenylcuprate to ethyl or methyl trans-2, 4-pentadienoate gave exclusively the 3, 6- diolefinic esters, which were isomerized to the desired 2, 6-diolefinic esters. The double- bond geometry of the vinyl unit is retained during the addition step.
