Stereoselective Synthesis of 3,5-Alkadienoic Esters from 2,4-Dienoic Isomers

Abstract
The treatment of (2E,4Z)-2,4-alkadienoic esters with lithium diisopropylamide (LDA) at −80 °C gave (3E,5E)-isomers with 81–98% stereoselectivity. In contrast, the treatment of (2E,4E)-isomers under the same conditions gave (3E,5Z)-isomers with 72–80% stereoselectivity. The application to the synthesis of megatomoic acid is described. Carbon-13 NMR data regarding these 3,5-dienoates were obtained.