Pigments of fungi. Part 51.1 Structure and stereochemistry of coupled pre-anthraquinones of the pseudophlegmacin type from Australian toadstools belonging to the genus Dermocybe

Abstract

(3′R,P)-Anhydropseudophlegmacin-9,10-quinone 6′,8′-di-O-methyl ether 4 and the corresponding 1,6′,8′-tri-O-methyl ether 5 are isolated together with the atropisomeric green pigments austroviridin B 10 and austroviridin A 11 from the fruiting bodies of indigenous Australian toadstools belonging to the genus Dermocybe. The structures of these pigments are determined by spectroscopic methods, while their absolute configurations are established from the respective CD spectra and by reductive cleavage of 5 to a mixture of (R)-torosachrysone 8-O-methyl ether 12 and emodin 1-O-methyl ether 14.