Incorporation of oxygen‐18 into the oxirane ring ofcis‐9,10‐epoxyoctadecanoic acid

The synthesis ofcis‐9,10‐epoxyoctadecanoic acid by tissue slices of wheat plants infected withPuccinia graminis tritici (Wheat stem rust) has been investigated further. Synthetic methylcis‐9,10‐epoxyoctadecanoate and the same ester isolated from incubation in an atmosphere containing18O2, or a medium containing H218O, were analyzed by mass spectrometry. These analyses revealed that molecular oxygen was incorporated into the oxirane ring ofcis‐9,10‐epoxyoctadecanoic acid.