The Chemistry of the Natural Order Cupressales. 49. The Configuration of Thujopsene.

Abstract
The relative configuration of thujopsene is established by chemical, infrared, optical rotatory dispersion, and proton magnetic resonance studies. The optical rotatory dispersion curves of some conjugated cyclopropyl ketones are discussed. The 3-membered rings contribute strongly to the Cotton effect but the contribution is of opposite sign to that predicted by the octant rule. The strong positive Cotton effects of the ketones establish the absolute configuration of thujopsene.