Absolute Configuration of Oplopanone Derivatives From Serphidium stenocephalum: ECD Spectra of Acyclic Ketones With Front-Octant Contributions

作者：Shafiq Nusrat; Saleem Muhammad; Riaz Naheed; Tousif Muhammad Imran; Jabbar Abdul; Tareen Rasool Bakhsh; Pescitelli Gennaro^*

来源：Chirality, 2014, 26(1): 39-43.

DOI：10.1002/chir.22263

• natural products
• structure elucidation
• electronic circular dichroism
• TDDFT calculations
• ketone octant rule

The electronic circular dichroism (ECD) spectra of two sesquiterpenoids (1 and 2) related to oplopanone, obtained from a methanolic extract of the plant Serphidium stenocephalum (Artemisia stenocephala), were measured and reproduced by means of time-dependent density functional theory (TDDFT) calculations, establishing their absolute configuration. The application of ketone octant rule for carbonyl n-* ECD band to compounds 1 and 2, which include an acyclic carbonyl group, was critically assessed. The peculiar oplopanone skeleton makes a straightforward application of the octant rule impossible, because of the uncertainty related to the shape of the so-called third nodal surface separating front and back octants. The various group contributions to the carbonyl n-* ECD band were estimated with TDDFT calculations on selected molecular models obtained by consecutive dissections from 1. Chirality 26:39-43, 2013.

• 出版日期2014-1