Phytochemical Study of <i>Senecio volckmannii</i> Assisted by CASE-3D with Residual Dipolar Couplings and Isotropic ¹H/¹³C NMR Chemical Shifts

Abstract

Nine new eremophilanolides, with seven known sesquiterpenoids, and 4-hydroxyacetophenone were isolated from the aerial parts of Senecio volckmannii var. volckmannii. The structures of these compounds were fully characterized using a combination of spectroscopic techniques including multinuclear and multidimensional NMR and mass spectrometry. The recently published Computer Assisted 3D Structure Elucidation (CASE-3D) protocol was applied in the configurational and conformational analysis of many of these eremophilanolides on the basis of Residual Dipolar Couplings (RDCs) and/or DFT predicted ¹H/¹³C chemical shifts.