Synthesis, characterization and antimicrobial activity of novel xanthene sulfonamide and carboxamide derivatives.

Xanthene intermediates 4a and 4b were obtained from the reduction of nitro xanthene derivatives 3a and 3b which were synthesized via condensation of dimedone with m-nitrobenzaldehyde and p-nitrobenzaldehyde, respectively. Then xanthene sulfonamide 6a-n, and xanthene carboxamide derivatives 8a-h were synthesized by reaction of amino xanthene 4a, 4b with sulfonyl chlorides 5a-g and acyl chlorides 7a-d. Structures of the novel amino xanthene compounds and xanthene sulfonamide/carboxamide derivatives were established by their spectral data and elemental analyses. Furthermore, all the synthesized compounds were tested in vitro for their antimicrobial activity. The results were compared with reference standard antibiotics, erythromycin and nystatin. 6c, 6f, 6m and 8b Compounds were found to display most effective antimicrobial activity against a series of bacteria and fungi.