The synthesis of (E)- and (Z)-3-hexenyl nonanoate, known constituents of essential oil containing plants, and two related compounds is reported. These compounds were assembled from nonanoyl chloride or nonanoic acid and the respective alcohols. In particular, it was found that the use of triethylamine as a co-solvent was necessary to avoid acid-mediated isomerization of the alkenes, which resulted in an inseparable mixture of products. The antimicrobial activity of the four hexenyl and hexyl nonanoate compounds was undertaken using microdilution minimum inhibitory concentration (MIC) analysis against eight test microorganisms. All four compounds demonstrated activity, with (E)-3-hexenyl nonanoate 1b having the highest inhibition (MIC value of 0.45 mg mL–1) against Pseudomonas aeruginosa ATCC 27858. Furthermore, this compound demonstrated the highest broad-spectrum activity (mean MIC value of 1.24 ± 0.50 mg mL–1) with noteworthy activity against all pathogens tested.Keywords: Essential oil constituent, (E)- and (Z)-3-hexenyl nonanoate, antimicrobial, ester synthesis, acid-induced alkene isomerizations PDF and supplemetary file attached.
