The structures of several derivatives of bisnorquassin (2a) are clarified. Chemical support for the mechanism of formation of this novel demethylation product of quassin (1a) is provided, which together with the recent X-ray diffraction study of bisnorquassin m-bromobenzoate (2d) offers an independent corroboration of the structure and stereochemistry of 1a deduced by Valenta.