Structure of cervinomycin, a novel xantone antibiotic active against anaerobe and mycoplasma

The structures of cervinomycins A1 (1) and A2 (2), a potent anti-anaerobic and anti-mycoplasmal antibiotic were investigated by means of recent NMR techniques of O-methyl ether (3) and C,O-dimethyl ether (4) obtained by methylation of 2 with CH3I in the presence of Ag2O. The antibiotic 2 posesses a polycyclic structure involving a xanthone skeleton. The structure of 1 was confirmed to be a hydroquinone of 2 from the evidences that oxidation of 1 with Ag2O and acetylation of 1 with (CH3CO)2O in pyridine afforded quantitatively 2 and triacetylcervinomycin A1 (7), respectively.