Determination by NMR methods of the structure and stereochemistry of astellatol, a new and unusual sesterterpene

The full structure of astellatol, a new complex sesterterpene isolated from Aspergillus variecolor, was determined solely by the use of one‐ and two‐dimensional NMR techniques. The carbon skeleton was deduced from a two‐dimensional INADEQUATE spectrum, and the proton shifts were deduced from a two‐dimensional CH correlation (HMQC) experiment. Analysis of a two‐dimensional proton DQFCOSY spectrum and a series of homonuclear NOE difference spectra allowed the determination of the full stereochemistry.