Psoroma leprolomum

Leprolomin (479), isolated from Psoroma leprolomum US), is a unique lichen diphenyl ether. Unlike other lichen diphenyl ethers which appear to be derived by hydrolysis or further modification of depsidones [cf. nor-lobariol (375)], leprolomin is apparently derived from phenolic coupling of two methylphloroacetophenone units and hence would appear to be biogenetically related to the usnic acids. From spectroscopic data of leprolomin and derivatives, six possible structures were considered, the unique structure being determined by X-ray diffraction of leprolomin triacetate US). 

Elix, J. A., U. Engkaninan, A. J. Jones, C. L. Raston, M. V. Sargent, and A. H. White Chemistry and Crystal Structure of Leprolomin, a Novel Diphenyl Ether from the Lichen Psoroma leprolomum. Austral. J. Chem. 31, 2057 (1978). 

From Psoroma leprolomum (Nyl.) Ras (Lichen collected from the baric of eucalypts) (compound 12) (0.6%) [6324],... 

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