Biogenesis of Geranium Oil Compounds: On the Origin of Oxygen in cis-/trans-Rose Oxide

By feeding experiments with labeled [1,1-2H2,18O]citronellol, it could be shown that Pelargonium graveolens is able to convert the fed precursor into cis-/trans-rose oxide. The labeling pattern and diastereomeric ratio of the resulting cis-/trans-rose oxides are in agreement with a mechanism which includes the enzymatic oxidation of citronellol in the allylic position and subsequent cyclization of the resulting diol to cis-/trans-rose oxide with...