1-(4-Chlorophenyl)-2-[4-hydroxy-3-(3-methoxybenzoyl)-1,1-dioxo-2H-1λ⁶,2-benzothiazin-2-yl]ethanone

Abstract

Key indicators: single-crystal X-ray study; T = 123 K; mean (C-C) = 0.004 Å; R factor = 0.054; wR factor = 0.111; data-to-parameter ratio = 15.8.In the title molecule, C 24 H 18 ClNO 6 S, the heterocyclic thiazine ring adopts a half-chair conformation with the S and N atoms displaced by 0.406 (5) and 0.444 (5) Å , respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The methoxybenzoyl and the chlorophenyl rings lie roughly parallel to each other, with a dihedral angle between the mean planes of these rings of 8.86 (10) . The molecular structure is consolidated by intramolecular O-HÁ Á ÁO and C-HÁ Á ÁO interactions and the crystal packing is stabilized by intermolecular O-HÁ Á ÁO and C-HÁ Á ÁCl hydrogen bonds. Table 1 Hydrogen-bond geometry (Å , ). etc. A few benzothiazines have also been studied as precursors for azodisperse dyes for polyesters (Rajagopal & Seshadri 1990). In continuation of our research on the synthesis of biologically active benzothiazine derivatives (Siddiqui et al., 2007;Ahmad et al., 2010), we herein report the synthesis and crystal structure of the title compound. Related literatureThe bond distances and angles in the title compound ( Fig. 1) agree very well with the corresponding bond distances and angles reported in closely related compounds (Siddiqui et al., 2008). The heterocyclic thiazine ring adopts a half chair conformation with the S1 and N1 atoms displaced by 0.406 (5) and 0.444 (5) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The methoxybenzoyl and the chlorophenyl rings lie roughly parallel to each other with a dihedral angle between the mean planes of these rings of 8.86 (10)°; the distance between the centroids of these rings is 3.828 (14) Å. The molecular structure of the title compound is consolidated by intramolecular interactions O3-H3O···O4 and C24-H24···O2 and the crystal packing is stabilized by intermolecular O3-H3O···O4 and C3-H3···Cl1 hydrogen bonds ( Fig. 2 and Table 1). S2. ExperimentalA mixture of (4-hydroxy-1,1-dioxido-2H-1,2-benzothiazin-3-yl)(3-methoxyphenyl) methanone (5.0 g, 0.015 mol), K 2 CO 3 (2.07 g, 0.015 mol) and 4-chlorophenacyl bromide (3.50 g, 0.015 mol) in acetonitrile (30 ml) was refluxed for 3 h. The contents of the flask were poured on ice cold HCl (5%, 30 ml). The precipitate of the title compound thus formed was