[4+2]-Cyclodimer of sabinone: formation, crystal structure, and NMR spectra

Oxidation of (+)-sabinol, (1S,3R,5S)-1-isopropyl-4-methylidenebicyclo[3.1.0]hexan-3-ol, by active MnO2 afforded not the expected sabinone but only its [4+2]-cyclodimer. The molecular structure of the latter was established by X-ray diffraction analysis. The 1H and 13C NMR spectra of this cyclodimer were interpreted using 2D NMR spectroscopy.