Synthesis and antimicrobial activity of pyranobenzoquinones related to the pyranonaphthoquinone antibiotics

The synthesis and antimicrobial activity of isochromane-type analogs of the pyranonaphthoquinone antibiotics are reported. Isochromane derivatives with ( 17a, b) and without ( 22a, b) a C-4 hydroxyl moiety and their corresponding quinones ( 19a and 23), were prepared. Both quinones exhibited antimicrobial activity against Staphylococcus aureus, Bacillus atrophaeus and Streptococcus agalactiae, while the related isochromanes were inactive. The results suggest that the quinone moiety is important for biological activity while the C-4 hydroxyl may not be essential. Quinones were active regardless the presence of the alcohol moiety. [Display omitted]