Research on potentially bioactive aza and thiaza polycyclic compounds containing a bridgehead nitrogen atom. III. Synthesis and antimicrobial activity of some 1,4‐benzothiazines and pyrrolobenzothiazines

Abstract

Cyclization reactions of N‐(2,2‐dialkoxyethyl)‐1,4‐benzothiazine lactams 2 and 1,4‐benzothiazine‐sulfones 10 lead to the corresponding pyrrolo[1,2,3‐de]‐1,4‐benzothiazines 4 and 12, respectively, by using the dioxane/p‐toluenesulfonic acid or polyphosphoric acid/chloroform systems. In contrast, in the same reaction conditions, 1,4‐benzothiazines 5a‐h do not provide the expected pyrrolobenzothiazines 7, and as for 5c‐h considerable amount of the 2‐amino‐phenyl‐sulfide 8 was obtained. The results of microbiological assays are reported.

Crystal structure of (Z)-2-benzylidene-4-methyl-2H-benzo[b][1,4]thiazin-3(4H)-one

“…For background to the pharmacological activity and potential applications of benzothiazines, see: Schiaffella et al (2006); Gupta et al (2009); Armenise et al (2000); Bansode et al (2009); Dixit et al (2009); Dixit et al (2008); Thomas et al (2003). For medicinal applications; see: Warren et al (1987); Armenise et al (2012); Sabatini et al (2008); Jacquot et al (2001); Kalluraya et al (2005); Munirajasekar et al (2011).…”

“…Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT-Plus (Bruker, 2009); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010 Over the years, 4H-1,4-benzothiazines have constituted an important class of heterocycles which, even when part of a complex molecule, possess a wide spectrum of biological activities (Schiaffella et al, 2006;Gupta et al, 2009;Armenise et al, 2000). Due to the presence of a fold along the nitrogen-sulfur axis, the biological activity of some 1,4-benzothiazines is similar to that of phenothiazines, featuring the same structural specificity (Bansode et al, 2009;Dixit et al, 2009;Dixit et al, 2008;Thomas et al, 2003).…”

Functionalized 1,4‐Benzothiazine: A Versatile Scaffold with Diverse Biological Properties

“…Over the years, 4 H ‐1,4‐benzothiazines have constituted an important class of heterocycles which, even when part of a complex molecule 1, possess a wide spectrum of biological activities 2–4. Due to the presence of a fold along the nitrogen sulfur axis, the biological activity of some 1,4‐benzothiazines is similar to that of phenothiazines, featuring the same structural specificity 5–10.…”

High yield synthesis of 4H‐1,4‐benzothiazine‐1,1‐dioxide derivatives

“…In particular the synthesis of the S-oxidized system, 4H-1,4-benzothiazine-1,1-dioxide, has been the object of several studies and patents for industrial and pharmacological applications [2][3][4][5]. The synthesis of such systems usually started from 2-aminobenzenethiols which were treated with -diketones to give the 2,3-disubstituted heterocyclic ring through the formation of an intermediate enaminoketone [4][5][6][7][8].…”