抄録
Aquayamycin, found in 1967, is an antibiotic isolated from Streptomyces misawanensis, and one of the most potent inhibitors of tyrosine hydroxylase and dopamine β-hydroxylase and active against Gram positive bacteria. Aquayamycin (1), n-butyl acetate solvate C_<25>H_<26>O_<10>・C_6H_<12>O_2, easily affords a triacetyl derivative. Hydrogenation of aquayamycin affords a dihydro derivative and acid treatment of dihydroaquayamycin affords a dehydrated product (3). On the other hand, treatment of aquayamycin with barium hydroxide affords an another dehydrated product (4a). Zinc-dust distillation of aquayamycin affords a naphthacene derivative. These results suggest that C-D ring junction of aquayamycin must be elaborated not only to afford benz(α)anthraquinone but also naphthacenequinone upon reaction conditions. The substituent of A ring has been shown to be 6-methyl-4,5-dihydroxy-tetrahydropyran by nmr spectra. Treatment of aquayamycin with 8% methanolic hydrogen chloride affords an anthraquinone methyl ester (7a). Treatment of 7a with base affords an acid (8), which affords pentaacetyl derivative of 4a by the treatment of acetic anhydride and pyridine at 105°. An interesting photochemical transformation of aquayamycin was observed. UV irradiation of aquayamycin in methanol affords an anthraquinone derivative (9), which is transformed into 4a by treatment with pyridine. Such photochemical rearrangement is understandable if C-D ring junction is trans. These evidences reasonably supports a unique naphthoquinone derivative of aquayamycin as shown 1.
