Essential oil of Plectranthus tenuicaulis for flavour and fragrance: Synthesis of derivatives from natural and synthetic 6,7‐epoxyocimenes

Abstract

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

Absolute configuration of the ocimene monoterpenoids from Artemisia absinthium

“…The conjugated double bonds system present in these ocimenes has been drawn either as a folded s ‐ cis or an extended s ‐ trans diene, and therefore, for the DFT calculation needed for the VCD studies, it is of relevance to know if both geometries coexist, in which case the relative abundance of them also has to be estimated, or if one atom arrangement highly predominates over the other one. Inspection of a 500 MHz 1 H NMR NOESY plot of 3 reveals the extended s ‐ trans geometry from the interactions of H‐4 at δ 2.41 and H‐7 at δ 6.76, while there is no evidence for an interaction between H‐7 at δ 6.76 and H‐10 at δ 1.85.…”

Chemical composition and biological activities of essential oil of Plectranthus tenuicaulis (Hook f.) leaves from Gabon

“…P. tenuicaulis leaves were collected in Mopia (South-eastern Gabon) and analyzed using Gas Chomatography (GC-FID), Gas Chromatography-Mass Spectrometry (GC-MS), 1 H and 13 C NMR (Agnaniet et al, 2011;Agrebi et al, 2012).…”

“…Despite the many papers that have been published on the chemistry of Plectranthus (Abdel-Mogib et al, 2002) before our works (Agnaniet et al, 2011;Agrebi et al, 2012), to our knowledge, there are no previous reports on either the biological or chemical activities of the volatile (or non-volatile) compounds of P. tenuicaulis (Hook).…”