Acute toxicity evaluation of derivatives of 6-nitro-2H-Benzo[1,4]thiazin-3-one

The synthesis and physico-chemical properties of five derivatives of 6-nitro-2Hbenzo[1,4]thiazin-3-one are described. Alkylation, amination following by benzoylation procedures were used in the molecular modification from that structure, on the positions N(4) and C(6): The derivatives 6-amino-2H-benzo[1,4]thiazin-3-one (BTZ 1R),4-methyl-6-nitro-2H-benzo[1,4]thiazin-3-one (BTZ 2), 6-amino-4-methyl-2H-benzo[1,4]thiazin-3-one (BTZ 2R), N-[4-methyl-3-oxo-3,4-dihydro-2H-benzo[1,4]thiazin-6-yl]-benzamide (BTZ 3) were synthesized and structurally characterized by spectroscopic infrared, mass, 1H-NMR and 13C-NMR. Their Lethal Doses (LD50) and toxic effects were evaluated. LD50 values were determined by probits methods. The LD50 results revealed that methylation at N-4 and the reduction of the nitro group to amine at C(6) resulted in increased toxicity.