Polyporic Acid and Derivatives

The structures of phlebiarubrone (23) and its dihydroxy derivative (25) were confirmed by synthesis involving methylenation of the potassium salts of polyporic acid (11) and atromentin (13), respectively, with methylene sulphate in the presence of sodium bicarbonate (22, 

Silica gel Merck 60 F254 (benzene ethyl formate formic acid = 10 5 3). 

Phlebiarubrone and polyporic acid have also been synthesised beginning with l,2-dimethoxy-4,5-(methylenedioxy)benzene l78). The co-occurrence of pigments (23) to (26) is of biogenetic interest in that it suggests a pattern of consecutive hydroxylations beginning with phlebiarubrone which has no parallel with polyporic acid itself. 

From mycelial mats of Phlebiopsis gigantea ( = Peniophora gigantea) the colourless 2, 3, 5-trimethoxy-p-terphenyl (27) has been isolated 134) which appears to be biogenetically related to polyporic acid. 

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