A sesquiterpene-enriched fraction of ginger oil was treated with the d
ienophile 4-phenyl-1,2,4-triazoline-3,5-dione (2), which selectively f
ormed a Diels-Alder adduct with the sesquiterpene hydrocarbon zingiber
ene (1). The adduct was purified by flash chromatography, then hydroly
zed to return zingiberene in good yield and >99% purity.