Metabolites of bird's nest fungi. Part 4. The isolation and structure determination of cybullol, a metabolite of Cyathus bulleri Brodie

Cybullol, a metabolite of Cyathus bulleri Brodie, has been shown to be (2S,5S,6S,10S)-cis-6, trans-10-dimethyl-r-2-cis-5-decalindiol (1) by a combination of chemical and physical methods. The mass spectra and the 1 H and 13 C magnetic resonance spectra of cybullol and derivatives are discussed. The absolute configuration of cybullol was deduced from the circular dichroism spectrum of the ketol 3. Cybullol has been transformed into the fungal metabolite (−)-geosmin (11). This correlation establishes the absolute configuration of (−)-geosmin.