Synthesis , Characterization and Biological Activities of 3 , 5-Diaryltetrahydro-N-[ ( phenylamino ) methyl ]-1 , 4-thiazine-1 , 1-dioxide

Synthesis of 3,5-diaryltetrahydro-N[(4’-nitroanilino)methyl-thiazine1,1-dioxide and N-[(4’-methylanilino)methyl-]-1,4-thiazine-1,1-dioxides by condensing 3,5-diaryl-tetrahydro-1,4-thiazine-1,1-dioxide with formaldehyde and 4-nitroaniline/4-methylaniline in the presence of hydrochloric acid is reported. The structures of the synthesized compounds have been confirmed by elemental and spectral analysis. The preliminary screening of the compounds for their biological activities gives significant results.


Introduction
The studies related to 1,4-thiomorpholine-1,1-dioxides are of recent origin [1][2][3] .Amongst the various methods known, condensation of either sulfonyl diacetic acid or dialkyl sulfonyl diaceate with araldehydes in the presence of ammonia or aliphatic amines was considered as an important route 4 .Heterocycles containing nitrogen and sulphur have potential pharmacological properties.One such class of compounds are 1,4-thiomorpholine-1,1dioxides which possess two important pharmacophores i.e.-NH-and -SO 2 -.
The structures of all these new products were elucidated by their elemental analysis, IR, 1 H NMR and 13 C NMR data.

Experimental
All the melting points were noted in open capillaries and are uncorrected.IR absorption spectra were recorded on a FT-IR spectrophotometer using KBr pellet and 1 HNMR spectra on AV-300 spectrometer (300 MHz) using DMSO as internal standard.Purity of the compounds was routinely checked by TLC using silica gel G.

Antimicrobial activity
The compounds 3a-j were evaluated in vitro for antibacterial activity against Escherchia coli, Klebsiella pnemoniae, Staphyylococcus aureus, Bacillus subtilis and for antifungal activity against Aspergillus niger and Aspergillus fumigatus in acetone of 25 µg concentration by cup-plate method.After 24 h of incubation at 37°C the zones of inhibition were measured in mm.The activity was compared with the known antibiotics, viz., norfloxacin, griseofulvin at the same concentration.The results are given in Table 1.Of the compounds tested, 3c and 3d, 3h and 3i inhibit the growth of tested bacteria and fungi at a minimum concentration of 25 µg/mL.3b and 3g showed moderate activity at higher concentrations ranging from 50 to 200 µg/mL.3a, 3f, 3e and 3j do not have inhibitioneven at 200 µg/mL.when compared to the standard norfloxacin and griseofulvin.

Conclusion
From the present investigation, the following conclusions can be drawn: • Thiazine compounds shows excellent biological activities • Further studies in these field is needed

Table 1 .
Antibacterial activities of compounds 3a-3j (Diameter of the zone of inhibition in mm)