An eco-friendly synthesis and antimicrobial activities of dihydro-2H-benzo- and naphtho-1,3-oxazine derivatives.

A series of 3,4-dihydro-2H-benzo[e]-, 2,3-dihydro-1H-naphtho[1,2-e]-, 3,4-dihydro-2H-naphtho[2,1-e][1,3]oxazine and 1,2-bis(3,4-dihydrobenzo[e][1,3]oxazin-3(4H)-yl)ethane derivatives was obtained through an eco-friendly Mannich type condensation-cyclization reaction of phenols or naphthols with formaldehyde and primary amines in water at ambient temperature. Preliminary in vitro antimicrobial activity of the synthesized compounds was assessed against six pathogenic fungi, two Gram-negative and two Gram-positive bacteria. Some of the screened compounds have shown significant in vitro antimicrobial effect. Cytotoxic activities of the lead compounds (2m, 2n, 3c and 3d) against mouse fibroblast cell line (L929) were determined by MTT method. The assay results revealed that these molecules offered remarkable viability (>90%) of L929 cells at concentration of 25 microg/mL.