Modified Clerodanes from the Essential Oil of Dodonea viscosa Leaves

International audience; Dodonea viscosa(L.) Jacq from Reunion Island (Indian Ocean) was investigated for itsleaf essential oil composition. The plant was extracted by hydrodistillation and its essential oilanalysed by gas chromatography coupled to mass spectrometry. This study revealed that oxygenatednor-diterpenes and diterpenes were one of the major chemical classes (>50%) mainly consisting ofthree modified cyclopropylclerodanes containing a bicyclo[5.4.0]undecane ring system: one newfuranoid norditerpene, dodovisate C, and two furanoid diterpenes, the known methyl dodovisate Aand the new methyl iso-dodovisate A. These three compounds were isolated by liquid chromatographyand their structures established on the basis of spectroscopic studies. The absolute configurationof dodovisate C was elucidated through a joint experimental and theoretical (B3LYP/6-311+G(d,p))electronic circular dichroism study. The relative configurations of methyl dodovisate A and methyliso-dodovisate A were determined using linear regressions of theoretical chemical shifts versusexperimental values with the (B3LYP/6-311+G(d,p)) method.