Structural Elucidation of Presilphiperfolane-7α,8α-diol, a Bioactive Sesquiterpenoid from Pulicaria vulgaris: A Combined Approach of Solvent-Induced Chemical Shifts, GIAO Calculation of Chemical Shifts, and Full Spin Analysis

Structural elucidation of a new triquinane sesquiterpenoid, presilphiperfolane-7α,8α-diol, 1a, isolated from Pulicaria vulgaris, was accomplished by combining solvent-induced removal of chemical shift degeneracy and computational (DFT-GIAO) prediction of NMR spectra with the analysis of 1H NMR splitting patterns. In addition to extensive NMR experiments (in 10 different solvents), MS, and FTIR, the identity of 1a was also confirmed by chemical...