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Microwave assisted synthesis and structure–activity relationship of 4-hydroxy-N′-[1-phenylethylidene]-2H/2-methyl-1,2-benzothiazine-3-carbohydrazide 1,1-dioxides as anti-microbial agents

Authors
Journal
European Journal of Medicinal Chemistry
0223-5234
Publisher
Elsevier
Volume
46
Issue
6
Identifiers
DOI: 10.1016/j.ejmech.2011.03.020
Keywords
  • 1
  • 2-Benzothiazine 1
  • 1-Dioxide
  • Benzothiazine Carbohydrazides
  • Microwaves Assisted Synthesis
  • 1
  • 4-Dihydropyrazolo[4
  • 3-C][1
  • 2]Benzothiazin-3-Ol 5
  • 5-Dioxide
  • Sodium Saccharin

Abstract

Abstract A series of 4-hydroxy-N′-[1-phenylethylidene]-2H/2-methyl, 1,2-benzothiazine-3-carbohydrazide 1,1-dioxides was synthesized from commercially available sodium saccharin. Base catalyzed ring expansion of methyl (1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3H)-yl)acetate followed by ultrasound mediated hydrazinolysis and subsequent reaction with 1-phenylethanones under the influence of microwaves yielded the title compounds. Besides, microwave assisted synthesis of 1,4-dihydropyrazolo[4,3-c][1,2]benzothiazin-3-ol 5,5-dioxide and 4-methyl-1,4-dihydropyrazolo[4,3-c][1,2]benzothiazin-3-ol 5,5-dioxide is also discussed. Most of the synthesized compounds were found to possess moderate to significant anti-microbial (anti-bacterial and anti-fungal) activities. It is found that compounds with greater lipophilicity (N-methyl analogues) possessed higher anti-bacterial activities.

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