Germacra‐1(10),5‐dien‐4α‐ol in Fortunella sp. leaf oils

AbstractThe composition of an oil sample isolated from leaves of Fortunella japonica (Thunb.) Swingle was investigated by combination of chromatographic and spectroscopic techniques. Among the compounds present at appreciable amounts, a special attention was brought to sesquiterpenes bearing a tertiary alcohol function and particularly to germacra‐1(10),5‐dien‐4α‐ol. Indeed, identification of diastereoisomers α and β of germacra‐1(10),5‐dien‐4‐ol has been the subject of controversy in the literature. We report here for the first time 13C NMR data of the α isomer. The criteria for differentiation of both diastereoisomers are discussed. In parallel, leaf oils from four other Fortunella species (F. crassifolia, F. hindsii, F. margarita and F. obovata) have been analyzed by GC(RI) and 13C NMR. The main components of the investigated Fortunella leaf oils were β‐elemol (8.7‐30.9%), germacrene D (2.1–16.3%), β‐eudesmol (4.6–13.1%) and Δ9‐10‐eremophilen‐11‐ol (1.4–11.2%). The occurrence of germacra‐1(10),5‐dien‐4α‐ol (1.1–7.7%) was observed in the five Fortunella leaf oils. Copyright © 2015 John Wiley & Sons, Ltd.