Application of vibrational circular dichroism for determining the absolute configuration of <i>Bubonium graveolens</i> plant major constituents

The determination of the absolute configuration of chiral molecules is essential because of the 3D arrangement of the atoms directly affects the chemical reactivity, biological activity, and therapeutic effects. Therefore, the absolute configuration of the major chiral components of the essential oil of Bubonium graveolens plant was determined by experimental VCD studies and DFT-calculated VCD spectra. The major components of B. graveolens plant studied were trans-chrysanthemyl acetate, δ-cadinol and δ-cadinene. The absolute configurations of trans-chrysathenyl acetate isomer were 5S,9R,10R, while the two isomers of δ-cadinol had 1R,4S,5R,10S and 1R,4R,5R,10S configurations. The absolute configurations of δ-cadinene isomers were 1R,10S and 1S,10R, respectively. Only one isomer of trans-chrysanthemyl acetate is present in this plant, while two isomers of δ-cadinol and δ-cadinene are available in B. graveolens. The predicted optical rotations of 5S,9R,10R of trans-chrysanthenyl acetate and 1S,10R of δ-cadinene were dextrorotatory, while the levorotatory signs were shown by 1R,4S,5R,10S and 1R,4R,5R,10S isomers of δ-cadinol and 1R,10S isomer of δ-cadinene, respectively. This approach has contributed to a deeper understanding of the structural, conformational and optical rotation properties of the chiral chemical species present in the B. graveolens plant. This research is highly useful in chemical asymmetric synthesis, drug development and effective fragrance preparations.