Abstract
Methylation of bikaverin (Ib) with diazomethane afforded monomethylbikaverin (Ic). Reductive acetylation of Ia, b, c with acetic anhydride and sodium acetate in the presence of zinc powder gave rise to benzoxanthene derivatives (IIc, d, e), respectively. Ib was hydrolyzed with aqueous sodium hydroxide to give everninic acid (III) and orcinol (IV). However, hydrolysis of Ic with alcoholic potassium hydroxide gave rise to cyclopentenoxanthene derivative (V). Ozonolysis of Ic gave xanthone derivative (XI).
