Chemistry and crystal structure of leprolomin, a novel diphenyl ether from the lichen psoroma leprolomum

The isolation and structural elucidation of 3′-(2″-acetyl-3″-hydroxy-5″-methoxy-4″-methylphenoxy)- 2′, 4′-dihydroxy-6′-methoxy-5′-methylacetophenone (leprolomin) (12), an unusual lichen metabolite probably derived biogenetically by C-O phenolic coupling of two units of C-methylphloroacetophe- none, is reported. Spectroscopic data on leprolomin and its derivatives allowed the structure to be limited to six possibilities; hence the crystal structure of leprolomin triacetate (15) was determined by X-ray diffraction.