Regioselective construction of six-membered fused heterocyclic rings via Pd/C-mediated C–C coupling followed by iodocyclization strategy: a new entry to 2H-1,2-benzothiazine-1,1-dioxides

Synthesis and Microbiological Evaluation of 1-(4-Methyl-6-Nitro-2h-Benzo[b] [1,4]thiazine-3(4h)-Ylidene)hydrazine-1,1-Dioxide Derivatives

“…[1,4]thiazin-3(4H)-one 3b (2.4 g, 0.01 mol) and potassium hydroxide (1.1g, 0.02 mol) were dissolved in DMSO (20 ml) and ethanol (25 ml). The mixture was stirred for 10 minutes before methyl iodide (1.2 ml, 0.02 mol) was added.…”

“…The title compound was prepared from 2,4-dimethyl-6-nitro-2H-benzo[b] [1,4]thiazin-3(4H)-one (4b) and hydrazine hydrate. Product was extracted with cyclohexane (3x50 ml) and purified by column chromatography on silica gel with a mixture of toluene-ethyl acetate (8:2) [1,4]thiazin-3(4H)-ylidene)hydrazine derivative (5a-f) (0.01 mol) in glacial acetic acid (20 ml) and 30% hydrogen peroxide (5 ml) were added and refluxed for 15 minutes.…”

“…Research in the synthetic chemistry of 1,4-benzothiazine derivatives during the past few decades was mainly attributed to their unique chemical, physical, and biological properties [1][2][3][4][5][6][7]. The synthesis of the sulfoxide system, many sulfones have been shown to exhibit biological activity for the industrial and pharmacological applications [8,9].…”

“…This condition has been enforced to the researcher to investigate for the new antimicrobial substance which is more efficient and having lesser side effect with improved physical properties. The alkylation of 4-N position of 2H-benzo [1,4]thiazine's affords bactericidal and antifungal derivatives. With the aim to investigate more potent antimicrobial activity of structurally related compounds, several 1-(4-methyl-6-nitro-2H-benzo[b] [1,4]thiazin-3(4H)-ylidene)hydrazine-1,1-dioxide derivatives 6a-f were synthesized (Fig.…”

“…The synthesis of compounds 6a-f started from the treatment of 2-chloro-5-nitroaniline 1 with sodium sulfide and sulfur gave sodium-2-amino-4-nitrobenzenethiol 2, which was cyclised with β-heloesters in ethanolic solution [10] to yield 2H-benzo[b] [1,4]thiazin-3(4H)-one derivatives 3a-b. Compounds 4a-b were synthesized by methylation of compounds 3a-b by methyl iodide in dimethyl sulfoxide (DMSO)/ethanol [11], which was refluxed with some nitrogen containing nucleophilic hydrazines in methanol [12] to yield 1-(4-methyl-6-nitro-2H-benzo[b] [1,4]thiazine-3-yl)hydrazines 5a-f. The further step, that is, the oxidation of the sulfur, was usually performed with 30% hydrogen peroxide in glacial acetic acid [13] to produce their sulfones 6a-f.…”