Synthesis of (<i>S</i>)-4-methylgeranyl esters, the pheromone components of the ponerine ant, <i>Holcoponera striatula</i>, and their (<i>R</i>)-isomers

(2E,4S)-3,4,7-Trimethylocta-2,6-dien-1-yl octanoate [(S)-1], decanoate [(S)-2], and dodecanoate [(S)-3] are the main trail pheromone components of the Dufour's gland secretion of the ponerine ant, Holcoponera striatula. We synthesized these pheromone components from an optically active alcohol, (R)-5, by using Johnson-Claisen rearrangement reaction as the key step for constructing a methyl-branched alkyl chain. The alcohol (R)-5 was prepared by using the enzymatic resolution of its racemate. To investigate the biological activity of the enantiomers of these pheromone components, we synthesized the antipodes (R)-1, (R)-2, and (R)-3.