Megastigma‐5,8‐dien‐4‐one, an aroma constituent of the yellow passion fruit andVirginiatobaccoPreparative gas chromatography allowed isolation of megastigma‐5, 8 (E)‐dien‐4‐one (3) from small subfractions of both yellow passion fruit andVirginiatobacco condensates. Along with3, the Z‐isomer4occurs in the aroma of the yellow passion fruit. Both these novel flavor compounds were synthesized by a two‐step, non‐biomimetic route starting from 2, 6, 6‐trimethylcyclohex‐2‐en‐1‐one. TheE‐isomer3was also formed by acid‐catalyzed dehydration/rearrangements of ionol‐ and damascol monoepoxides5, 6, 7, 8and hydroxy‐ionols and ‐damascol9, 10and11. Such a biomimetic conversion indirectly supports the assumption that3and4might originate from the oxidative degradation of carotenoid prec