Straightforward Preparation of (2E,4Z)-2,4-Heptadien-1-ol and (2E,4Z)-2,4-Heptadienal

Abstract

A concise synthesis of (2E,4Z)-2,4-heptadien-1-ol and (2E,4Z)-2,4-heptadienal is presented. Commercially available (Z)-2-penten-1-ol was converted to ethyl-(2E,4Z)-2,4-heptadienoate by reaction with activated MnO₂ and (carboethoxymethylene)triphenylphosphorane in the presence of benzoic acid as a catalyst. Ethyl-(2E,4Z)-2,4-heptadienoate was converted to (2E,4Z)-2,4-heptadien-1-ol with LiAlH₄. The alcohol was partially oxidized to (2E,4Z)-2,4-heptadienal with MnO₂. The title compounds are male-specific, antennally active volatile compounds from the Saltcedar leaf beetle, Diorhabda elongata Brulle (Coleoptera: Chrysomelidae) and have potential use in the biological control of the invasive weed saltcedar (Tamarix spp).

Keywords:

• Ethyl-(2E,4Z)-2,4-heptadienoate
• (2E,4Z)-2,4-heptadien-1-ol
• (2E,4Z)-2,4-heptadienal
• Oxidation-Wittig reaction
• Saltcedar leaf beetle
• Diorabda elongata Brulle (Coleoptera: Chrysomelidae)

Acknowledgments

I thank Bruce W. Zilkowski and Robert J. Bartelt for acquiring mass spectral data, David Weisleder for acquiring NMR spectra, and Robert J. Bartelt for helpful discussions.