The Assignment of the Absolute Configuration of Non-Cyclic Sesquiterpenes by Vibrational and Electronic Circular Dichroism: The Example of <i>Chiliadenus lopadusanus</i> Metabolites

Abstract

9-Hydroxynerolidol, 9-oxonerolidol, and chiliadenol B are three farnesane-type sesquiterpenoids isolated from Chiliadenus lopadusanus that have shown an interesting activity against human pathogens as Gram+ and Gram− bacteria resistant to antibiotics. However, the absolute configuration (AC) of these interesting sesquiterpenes has not been assigned so far. Vibrational and electronic circular dichroism spectra have been recorded and correlations are pointed out for the three compounds. Density functional theory (DFT) calculations are used in conjunction with Mosher’s method of investigation to assign AC. Statistical analysis is considered to quantitatively define the choice of AC from VCD spectra.

Keywords

• <i>Chiliadenus lopadusanus</i>
• farnesane-type sesquiterpenes
• 9-hydroxynerolidol
• 9-oxonerolidol and chiliadenol B
• VCD
• ECD