Quadrone, a new antitumor agent from

Structure of a new antibiotic, terrecyclol, from Aspergillus terreus Thom.

“…This experiment was conducted with the diazomethane adduct of the methyl ester of II, the 400 MHz !H-NMR spectrum of which was completely analyzed.2* The results are shown in Scheme 1, and the relative stereochemistry of quadrone, which was proposed by Ranieri and Calton,4) was supported by the NOE experiment.…”

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

“…The synthesis of the cytotoxic sesquiterpenoid quadrone ( 55 ) from Aspergillus terreus [52–53] started from tricyclic ketone 52 [54], which was converted into tricycle 53 in 12 steps. Trans -divinylcyclopropane 53 underwent the desired DVCPR after trans - cis -isomerization of the vinyl moiety at 175 °C, forming bridged tetracycle 54 , which already contained the crucial seven-membered ring present in the target molecule 55 .…”

The Use of Carbon-13 Nuclear Magnetic Resonance Spectroscopy in Natural Products Chemistry

“…Shielding data have been determined for ail ant hone (410), chaparrinone (411), glaucarubinone (412), glaucarubin (413), samaderine B (414), quassin (415), brucein B (416) and brucein C (417). Shielding data have been determined for ail ant hone (410), chaparrinone (411), glaucarubinone (412), glaucarubin (413), samaderine B (414), quassin (415), brucein B (416) and brucein C (417).…”