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Water distilled essential oils from leaves of Plectranthus tenuicaulis (Hook. f.) J. K. Morton collected in Gabon were analyzed using GC-FID and GC-MS. The main constituent, unusual within the genus Plectranthus, was isolated and formally identified as being the (+)-(R)enantiomer of (E)-6,7-epoxyocimene [(E)-myroxide]. This enantiomer, which represents about 75% of the essential oil, has been previously identified as a pheromone emitted by the male fruit-spotting bug Amblypelta nitida; this insect is responsible of destruction of most fruit crops in tropical and subtropical areas. The potential application of P. tenuicaulis essential oil in crop protection programs is discussed and the atypical chemical profile of the gabonese essential oil is compared with those previously reported in the genus Plectranthus (or Coleus).

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International audience(R)-(E)-6,7-Epoxyocimene, the major constituent of the essential oil from Plectranthus tenuicaulis, as well as the racemic (Z)-isomer previously synthesized from commercial (Z)-beta-ocimene were used as starting material for the synthesis of fragrant derivatives. Among the 14 compounds obtained from these precursors (alcohols, diols, diepoxy, sulfur and carbonyl derivatives), four were described for the first time and three were enantiomerically pure. All compounds were fully characterized by one- and two-dimensional nuclear magnetic resonance analysis as well as by gas chromatography and mass spectroscopy (electron ionization). Additionally, their odour properties were evaluate