Crystal structure of (E)-2-benzyl­idene-4-[(3-phenyl-4,5-di­hydro­isoxazol-5-yl)meth­yl]-2H-benzo[b][1,4]thia­zin-3(4H)-one

Nada Kheira Sebbar; Mohamed Ellouz; El Mokhtar Essassi; Mohamed Saadi; Lahcen El Ammari

doi:10.1107/S2056989015009755

. 2015 May 23;71(Pt 6):o423–o424. doi: 10.1107/S2056989015009755

Crystal structure of (E)-2-benzylidene-4-[(3-phenyl-4,5-dihydroisoxazol-5-yl)methyl]-2H-benzo[b][1,4]thiazin-3(4H)-one

Nada Kheira Sebbar ^a, Mohamed Ellouz ^a, El Mokhtar Essassi ^a,^b,^*, Mohamed Saadi ^c, Lahcen El Ammari ^c

PMCID: PMC4459330 PMID: 26090204

Abstract

In the title compound, C₂₅H₂₀N₂O₂S, the dihydroisoxazole ring exhibits an envelope conformation with the methine atom being the flap, while the 1,4-thiazine ring displays a screw-boat conformation. The six-membered ring fused to the 1,4-thiazine ring makes dihedral angles of 63.04 (2) and 54.7 (2)° with the mean planes through the five-membered heterocycle and the attached phenyl ring, respectively. The phenyl group connected to the 1,4-thiazine ring is disordered over two sites [major component = 0.57 (2)]. The most prominent interactions in the crystal structure are C—H⋯O hydrogen bonds that link molecules, forming inversion dimers, and C—H⋯N hydrogen bonds that link the dimers into columns parallel to the b axis.

Keywords: crystal structure; benzothiazine; dihydroisoxazole; C—H⋯O,N hydrogen bonding

Related literature

For the biological activity and pharmaceutical properties of benzothiazines and their derivatives, see: Fringuelli et al. (1998 ▸); Rathore & Kumar (2006 ▸); Barazarte et al. (2008 ▸); Bakavoli et al. (2007 ▸). For related structures, see: Saeed et al. (2010 ▸); Afrakssou et al. (2011 ▸); Sebbar et al. (2014a ▸,b ▸).

Experimental

Crystal data

C₂₅H₂₀N₂O₂S
M _r = 412.49
Monoclinic,
a = 17.4463 (16) Å
b = 5.3024 (4) Å
c = 22.778 (2) Å
β = 106.370 (5)°
V = 2021.7 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.19 mm⁻¹
T = 296 K
0.36 × 0.31 × 0.26 mm

Data collection

Bruker X8 APEX diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▸) T _min = 0.504, T _max = 0.748
27864 measured reflections
4149 independent reflections
1980 reflections with I > 2σ(I)
R _int = 0.095

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.145
S = 1.00
4149 reflections
321 parameters
H-atom parameters constrained
Δρ_max = 0.48 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▸); cell refinement: SAINT (Bruker, 2009 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▸) and ORTEP-3 for Windows (Farrugia, 2012 ▸); software used to prepare material for publication: PLATON (Spek, 2009 ▸) and publCIF (Westrip, 2010 ▸).

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989015009755/tk5368sup1.cif

e-71-0o423-sup1.cif^{(1.1MB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015009755/tk5368Isup2.hkl

e-71-0o423-Isup2.hkl^{(330.7KB, hkl)}

Click here for additional data file.^{(7.9KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015009755/tk5368Isup3.cml

Click here for additional data file.^{(1.2MB, tif)}

. DOI: 10.1107/S2056989015009755/tk5368fig1.tif

Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles. One phenyl ring is disordered over two positions.

CCDC reference: 1402017

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C21H21O1ⁱ	0.93	2.43	3.339(4)	166
C18H18BN2ⁱⁱ	0.97	2.56	3.526(3)	178

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements and the University Mohammed V, Rabat, Morocco, for financial support.

supplementary crystallographic information

S1. Comment

Recently, a number of pharmacological tests revealed that 2H-1,4- benzothiazine derivatives present various biological activities including antifungal (Fringuelli et al., 1998), antimicrobial (Rathore et al., 2006), antimalarial (Barazarte et al., 2008) and 15-lipoxygenase inhibition properties (Bakavoli et al., 2007). In this work, we aim to prepare new derivatives of 3,4-dihydro-2H- benzo[b]1,4-thiazine for biological evaluation, as in the previous studies (Saeed et al., 2010; Afrakssou et al., 2011; Sebbar et al., 2014a, 2014b. In the reaction, the oxime reacts with (E)-4-allyl-2-benzylidene-2H-benzo[b][1,4]thiazin-3(4H)-one in a biphasic medium (water-chloroform) at 0°C over 4 h to give a unique cycloadduct: (E)-2-benzylidene-4-((3-phenyl-4, 5-dihydroisoxazol-5-yl)methyl)-2H- benzo[b][1,4]thiazin-3(4H)-one (Scheme 1).

The molecule of the title compound is build up from two fused six-membered rings linked, via two –CH₂– groups, on the one hand to a phenyl ring and on the other hand to the 3-phenyl-4,5-dihydroisoxazole system as shown in Fig. 1. The (C1 to C6) benzene cycle form dihedral angles of 63.04 (2)\ and 54.7 (2)° with the mean planes through the five-membered heterocycle and the attached phenyl ring, respectively. In the crystal, the molecules are linked by hydrogen bond (Table 1) in the way to build a dimers as shown in Fig. 2.

S2. Experimental

To a solution of (E)-4-allyl-2-benzylidene-3,4-dihydro-2H- benzo[b]1,4-thiazine (1 g, 3.4 mmol) and benzaldoxime (0.81 ml, 6.8 mmol) in chloroform (30 ml) was added dropwise a 24% sodium hypochlorite solution (10 ml) at 273 K. Stirring was continued for 4 h. The organic layer was dried over Na₂SO₄ and the solvent was evaporated under reduced pressure. The residue was then purified by column chromatography on silica gel using a mixture of hexane/ethyl acetate (v/v = 80/20) as eluent. Colourless crystals were isolated when the solvent was allowed to evaporate (yield: 74%).