The sesquiterpenoid nootkatone and the absolute configuration of a dibromo derivative
Nootkatone, or (4R,4aS,6R)-4,4a,5,6,7,8-hexahydro-4,4a-dimethyl-6-(1-methylethenyl)naphthalen-2 (3H)-one, C15H22O, a sesquiterpene with strong repellent properties against Formosan subterranean termites and other insects, has the valencene skeleton. The dibromo derivative (1S,3R,4S,4aS,6R,8aR)-1,3-dibromo-6-isopropyl-4,4a-dimethyl-1,2,3,4,5,6,7,8-octa hydronaphthalen-2-one. C15H24Br2O, has two independent molecules in the asymmetric unit, which differ in the rotation of the isopropyl group with respect to the main skeleton. The C-Br distances are in the range 1.950 (4)-1.960 (4) Å. Both independent molecules form zigzag chains, with very short intermolecular carbonyl-carbonyl interactions, having the perpendicular motif and O⋯C distances of 2.886 (6) and 2.898 (6) Å. These chains are flanked by intermolecular Br⋯Br interactions of distances in the range 4.067 (1)-4.218 (1) Å. The absolute configuration of the dibromo derivative was determined, from which that of nootkatone was inferred.
Publication Source (Journal or Book title)
Acta Crystallographica Section C: Crystal Structure Communications
Sauer, A., Fronczek, F., Zhu, B., Crowe, W., Henderson, G., & Laine, R. (2003). The sesquiterpenoid nootkatone and the absolute configuration of a dibromo derivative. Acta Crystallographica Section C: Crystal Structure Communications, 59 (5) https://doi.org/10.1107/S010827010300684X