(Z)-3-(3,4-Dimeth­oxy­benzyl­idene)-2,3-dihydro-1,5-benzothia­zepin-4(5H)-one

M Bakthadoss; R Selvakumar; N Manikandan; S Murugavel

doi:10.1107/S1600536813007423

. 2013 Mar 23;69(Pt 4):o562–o563. doi: 10.1107/S1600536813007423

(Z)-3-(3,4-Dimethoxybenzylidene)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one

M Bakthadoss ^a,^‡, R Selvakumar ^a, N Manikandan ^b, S Murugavel ^c,^*

PMCID: PMC3629613 PMID: 23634100

Abstract

In the title compound, C₁₈H₁₇NO₃S, the seven-membered thiazepine ring adopts a slightly distorted sofa conformation. The dihedral angle between the mean plane of the benzothiazepine ring system and the benzene ring is 5.9 (1)°. The molecular conformation is stabilized by an intramolecular C—H⋯S hydrogen bond, which generates an S(7) ring motif. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link inversion-related molecules into dimers, incorporating R ₁ ²(6) and R ₂ ²(8) ring motifs; the acceptor O atom is bifurcated. These dimers are further linked by C—H⋯O hydrogen bonds, forming supramolecular tapes running along the a axis. These are connected into the three-dimensional architecture by C—H⋯π interactions.

Related literature

For the pharmaceutical properties of thiazepine derivatives, see: Tomascovic et al. (2000 ▶); Rajsner et al. (1971 ▶); Metys et al. (1965 ▶). For related structures, see: Lakshmanan et al. (2012 ▶); Selvakumar et al. (2012 ▶); Murugavel et al. (2013 ▶). For ring-puckering parameters, see: Cremer & Pople (1975 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). graphic file with name e-69-0o562-scheme1.jpg

Experimental

Crystal data

C₁₈H₁₇NO₃S
M _r = 327.39
Triclinic,
a = 7.0249 (4) Å
b = 10.7949 (7) Å
c = 10.8826 (7) Å
α = 91.783 (3)°
β = 97.562 (2)°
γ = 108.512 (2)°
V = 773.42 (8) Å³
Z = 2
Mo Kα radiation
μ = 0.22 mm⁻¹
T = 293 K
0.23 × 0.21 × 0.15 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.950, T _max = 0.967
14052 measured reflections
3082 independent reflections
2545 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.121
S = 1.06
3082 reflections
210 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: APEX2 and SAINT (Bruker, 2004 ▶); data reduction: SAINT and XPREP (Bruker, 2004 ▶); 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: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Click here for additional data file.^{(25.6KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536813007423/tk5207sup1.cif

e-69-0o562-sup1.cif^{(25.6KB, cif)}

Click here for additional data file.^{(148.1KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813007423/tk5207Isup2.hkl

e-69-0o562-Isup2.hkl^{(148.1KB, hkl)}

Click here for additional data file.^{(6.3KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813007423/tk5207Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12—H12⋯S1	0.93	2.76	3.605 (2)	151
N1—H1⋯O1ⁱ	0.86	2.12	2.967 (2)	170
C6—H6⋯O1ⁱ	0.93	2.52	3.318 (2)	144
C5—H5⋯O3ⁱⁱ	0.93	2.46	3.377 (3)	167
C17—H17C⋯Cg1ⁱⁱⁱ	0.96	2.84	3.724 (2)	154
C18—H18A⋯Cg1^iv	0.96	2.90	3.841 (3)	166

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

Acknowledgments

The authors thank Dr Babu Vargheese, SAIF, IIT, Madras, India, for the data collection.

supplementary crystallographic information

Comment

The title compound is used as an intermediate for the synthesis of dosulepin, which is an antidepressant of the tricyclic family. Dosulepin prevents reabsorbing of serotonin and noradrenaline in the brain, helps to prolong the mood lightening effect of any released noradrenaline and serotonin, thus relieving depression. The dibenzo[c,e]thiazepin derivatives exhibit chiroptical properties (Tomascovic et al., 2000). Dibenzo[b,e]thiazepin-5,5-dioxide derivatives possess anti-histamine and anti-allergenic activities (Rajsner et al., 1971). Benzene thiazepin derivatives are identified as a new type of effective anti-histamine compounds (Metys et al., 1965). In view of this biological importance, the crystal structure of the title compound has been carried out and the results are presented here.

Fig. 1. shows a displacement ellipsoid plot of (I), with the atom numbering scheme. The seven membered thiazepine ring (N1/S1/C1/C2/C7/C8/C9) adopts slightly distorted sofa conformation as indicated by puckering parameters (Cremer & Pople, 1975): QT = 0.7878 (17) Å, φ₂ = 57.8 (2)° and φ₃ = 16.3 (2)°. The atom O1 deviates by 0.463 (1) Å from the least-squares plane of the thiazepin ring. The dihedral angle between the benzothiazepin ring system and the benzene ring is 5.9 (1)°. The sum of angles at N1 atom of the thiazepin ring (359.9°) is in accordance with sp² hybridization. The geometric parameters of the title molecule agree well with those reported for similar structures (Selvakumar et al., 2012, Lakshmanan et al., 2012).

The molecular conformation is stabilized by an intramolecular C12—H12···S1 hydrogen bond, which generates an S(7) ring motif (Bernstein et al., 1995). In the crystal, intermolecular bifurcated acceptor N1—H1···O1ⁱ and C6—H6···O1ⁱ (Table 1) hydrogen bonds link inverted-related molecules into dimers, incorporating R₁²(6) and R₂²(8) ring motifs. These dimers are further linked by C5—H5···O3ⁱⁱ (Table 1) hydrogen bonds forming supramolecular tapes running along the a axis (Fig. 2). The crystal packing is further stabilized by C17—H17C···Cg interactions, in which atom C17 acts as a hydrogen bond donor via H17C, to a symmetry related C2–C7 benzene ring (Table 1), thereby generating cyclic centrosymmetric dimers. This dimers are further linked by C18—H18A···Cg^iv (Table 1) interactions into supramolecular tapes running along the b axis (Fig. 3 and Table 1; Cg is the centroid of the C2–C7 benzene ring).

Experimental

A mixture of (Z)-methyl 2-(bromomethyl)-3-(3,4-dimethoxyphenyl)acrylate 2 mmol) and o-aminothiophenol (2 mmol) in the presence of potassium tert-butoxide (4.8 mmol) in dry THF (10 ml) was stirred at room temperature for 1 h. After the completion of the reaction as indicated by TLC, the reaction mixture was concentrated and the resulting crude mass was diluted with water (20 ml) and extracted with ethyl acetate (3 x 20 ml). The organic layer was washed with brine (2 x 20 ml) and dried over anhydrous sodium sulfate. The organic layer was concentrated, which successfully provide the crude final product ((Z)-3-(3,4-dimethoxybenzylidene)-2,3-dihydrobenzo[b][1,4]). The final product was purified by column chromatography on silica gel to afford the title compound in good yield (46%). Single crystals suitable for X-ray diffraction were obtained by slow evaporation of its ethylacetate solution at room temperature.