STUDIES ON TERPENOIDS AND STEROIDS .25. COMPLETE H-1-NMR AND C-13-NMR SPECTRAL ASSIGNMENTS OF SALACIQUINONE, A NEW 7-OXO-QUINONEMETHIDE DINORTRITERPENOID

A new 7-oxo-quinonemethide dinortriterpenoid, salaciquinone [1], and a known quinonemethide dinortriterpenoid, isoiguesterin [3], were isolated from the toot bark of Salacia reticulata var. beta-diandra (Celastraceae). The structure elucidation of salaciquinone was based on derailed 2D and nOe-difference nmr spectroscopy, leading to the complete assignment of the H-1- and C-13-nmr spectra and revision of some H-1-nmr spectral assignments made previously for the related 7-oxo-quinonemethide nortriterpenoid, dispermoquinone [2]. Complete H-1- and C-13-nmr spectral assignments of isoiguesterin were also made, also leading to revision of some C-13-nmr assignments previously made for this compound.