Wt: 431.50,M.P.: 209–210 °C; Yield 59% Rf 0.80; IR (cm−1): 1700(C]O ester), 3142(N–H), 1142, 1326 (>S]O); 1513 (C]N); 3479 (NH–C]O), 1H NMR

(δppm): 2.11 (s, 6H, Di-Methyl), 7.14–7.94 (m, 14H, Ar–H); Elemental analysis for C24H21N3O3S; Calculated: C, 66.74; H, 4.86; SB203580 ic50 N, 9.70; O,11.12; S,7.41 Found: C, 66.83; H, 4.83; N, 9.70; O,11.21; S,7.49, [M + H]+: 432.16. Wt: 443.60,M.P.: 207–208 °C; Yield 81% Rf 0.80; IR (cm−1): 1705(C]O ester), 3130(NH),1175, 1313 (>S]O); 1516 (C]N); 3404 (NH–C]O), 1H NMR (δppm): 2.12 (s, 6H, Di-Methyl), 1.34–1.82 (m, 20H, –(CH2)10–), 3.53(m,–NH–CH-)7.38–7.68 (m, 4H, Ar–H); Elemental analysis for C24H33N3O3S; Calculated: C, 64.92; H, 7.43; N, 9.46; O,10.82; S,7.21 Found: C, 64.98; H, 7.49; N, 9.89; O,10.73; S,7.10, [M + H]+: 444.56. The activity was determined using the disc diffusion method i.e. the zone of inhibition was measured in mm. All the compounds, (2a–j) were screened in vitro at a concentration of 100 μg/ml using DMSO as a solvent. Their antibacterial activities against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative strains (Escherichia coli and Pseudomonas aeruginosa) were measured. Antifungal

evaluation was carried out against Candida albicans and Aspergillus niger at a concentration of 100 μg/ml. The antibacterial drug ciprofloxacin (10 μg/disc) and antifungal drug fluconazole (10 μg/disc) EGFR inhibitor were also tested under similar conditions against these organisms. Each experiment was performed in triplicate and the average tabulated. We synthesized novel N-alkyl-2-(3,5-dimethyl-1,1-dioxido-2H-1,2,6-thiadiazin-4-yl)benzamides bearing novel substituent groups at the fourth position of the 1,2,6-thiadiazine ring. Historically acyl chloride mediated procedures for preparation of amides have been employed. In our study we found that at the temperatures typically used for these reactions there was decomposition of our starting material. In an effort to overcome this we then employed DCC at room temperature. almost The byproduct DCU persisted in the workup of

the reaction and thus any products could not be purified. 18 In the end we used CDI for the coupling reaction which afforded typical yields of 80+%. The spectroscopic data for all the compounds were consistent with those observed for similar 1,2,6-thiadiazine 1,1-dioxide molecules and our compounds were fully characterized using by 1H NMR, high-resolution mass spectroscopy and elemental analysis. 19 All of the compounds demonstrated activity against the bacterial strains. In particular, this family of molecules was more active against the Gram-positive species S. aureus and B. subtilis than the Gram-negative E. coli and P. aeruginosa. The best results were achieved with molecules that had a cyclic aliphatic group i.e.2c, 2e and 2g (See Scheme 2). We were unable to synthesize the derivative with a benzyl group at the same position.