Ethyl 2-amino-4-(3-nitro­phen­yl)-4H-1-benzothieno[3,2-b]pyran-3-carboxyl­ate

Mohamed Bakhouch; Ghali Al Houari; Mohamed El Yazidi; Mohamed Saadi; Lahcen El Ammari

doi:10.1107/S1600536814008538

. 2014 Apr 18;70(Pt 5):o587. doi: 10.1107/S1600536814008538

Ethyl 2-amino-4-(3-nitrophenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate

Mohamed Bakhouch ^a, Ghali Al Houari ^a, Mohamed El Yazidi ^a,^*, Mohamed Saadi ^b, Lahcen El Ammari ^b

PMCID: PMC4011203 PMID: 24860386

Abstract

The molecule of the title compound, C₂₀H₁₆N₂O₅S, is built up by one fused five-membered and two fused six-membered rings linked to ethoxycarbonyl and 3-nitrophenyl groups. The benzothienopyran ring system is nearly planar (r.m.s deviation = 0.0392 Å) and forms a dihedral angle of 86.90 (6)° with the aromatic ring of the nitrobenzene group. In the crystal, molecules are linked by N—H⋯O hydrogen bonds and by π–π interactions between the phenyl ring and the six-membered heterocyle [intercentroid distance = 3.5819 (8) Å], forming a three-dimensional network.

Related literature

For background to the organic synthesis of the title compound, see: House (1972 ▶); Kabashima et al. (2000 ▶); Jung (1991 ▶). For the preparation of heterocyclic compounds using condensation reactions, see: Boughaleb et al. (2011 ▶); Cabiddu et al. (2002 ▶); Pradhan & Asish (2005 ▶).

Experimental

Crystal data

C₂₀H₁₆N₂O₅S
M _r = 396.41
Triclinic,
a = 8.3670 (2) Å
b = 9.4319 (2) Å
c = 12.8948 (4) Å
α = 102.505 (1)°
β = 106.493 (1)°
γ = 94.840 (1)°
V = 940.96 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 296 K
0.42 × 0.31 × 0.26 mm

Data collection

Bruker X8 APEX diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.673, T _max = 0.746
20668 measured reflections
4857 independent reflections
3954 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.137
S = 1.05
4857 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.25 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: 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/S1600536814008538/rz5118sup1.cif

e-70-0o587-sup1.cif^{(24.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814008538/rz5118Isup2.hkl

e-70-0o587-Isup2.hkl^{(237.9KB, hkl)}

Click here for additional data file.^{(7KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814008538/rz5118Isup3.cml

CCDC reference: 997474

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1B⋯O2	0.86	2.09	2.6950 (17)	127
N1—H1B⋯O2ⁱ	0.86	2.30	3.0327 (17)	143
N1—H1A⋯O5ⁱⁱ	0.86	2.30	3.1489 (19)	169

Open in a new tab

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.

supplementary crystallographic information

1. Comment

The Michael reaction is one of the most efficient methods for effecting carbon–carbon bond formation and has wide synthetic applications (House, 1972; Kabashima et al., 2000). This reaction and its close variants have been extensively used in organic synthesis (Jung, 1991). Generally, Michael additions are conducted in a suitable solvent in the presence of a strong base either at room or at elevated temperatures. In continuing our previous works on the preparation of hetrocyclic compounds by using condensation reactions (Boughaleb et al., 2011), we now wish to describe the behavior of ethylcyanoacetate with respect to (Z)-2-(3-nitrobenzylidene)-1-benzo[b]thiophen-3(2H)-one and derivatives in ethanol, with the presence of piperidine as a basic catalyst (Cabiddu et al., 2002; Pradhan & Asish, 2005). We have shown that cyclocondensation start with a Michael 1,4-additon, followed by intramolecular cyclization via nucleophilic addition of the hydroxyl group to the cyano group and not onto the carboxylate, to afford the tricyclic heterocycle ethyl2-amino-4-(3-nitrophenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate.

The molecule of the title compound, is formed by tree fused rings linked to an ethyl-3-carboxylate nd a 3-nitrophenyl group as shown in Fig. 1. The three fused rings (S1/C1–C11/O1) are almost coplanar, with the maximum deviation from the mean plane of -0.089 (2) Å at C9, and make a dihedral angle of 86.90 (6)° with the plane through the attached nitrophenyl group.

In the crystal, molecules are linked by N—H···O hydrogen bonds and by π–π interactions in a three-dimensional network as shown in Fig. 2 and Table 1.

2. Experimental

In a 100 ml flask equipped with a condenser was dissolved 4 mmol of (Z)-2-(3-nitrobenzylidene)-1-benzo[b]thiophen-3(2H)-one and 5 mmol of ethyl cyanoacetate in 30 ml of ethanol. Then, 1 ml of piperidine was added, and the reaction mixture was refluxed for 6 h. Thin layer chromatography revealed the formation of a single product. The organic phase was evaporated under reduce pressure. The resulting residue was recristallized from ethanol (Yield: 68%; m.p.: 493 K).