Ethyl 7-oxo-3,5-diphenyl-1,4-diazepane-2-carboxyl­ate

G Jagadeesan; K Sethusankar; P Selvakumar; S Thennarasu; A B Mandal

doi:10.1107/S1600536812017084

. 2012 Apr 25;68(Pt 5):o1525–o1526. doi: 10.1107/S1600536812017084

Ethyl 7-oxo-3,5-diphenyl-1,4-diazepane-2-carboxylate

G Jagadeesan ^a, K Sethusankar ^b,^*, P Selvakumar ^c, S Thennarasu ^c, A B Mandal ^c

PMCID: PMC3344629 PMID: 22590391

Abstract

The title compound, C₂₀H₂₂N₂O₃, crystallizes with two independent molecules in the asymmetric unit. In both molecules, the diazepane rings adopt chair conformations. The mean planes of the diazepane rings in the two molecules form dihedral angles of 71.6 (4)/40.3 (5) and 75.9 (5)/58.6 (7)° with the neighbouring benzene rings. The carbonyl-group O atoms deviate significantly from the diazepane rings, by 0.685 (14) and 0.498 (13) Å. The ethoxycarbonyl groups show conformational difference between two molecules, as reflected in the orientation of the carbonyl O atoms and the C—C—O—C torsion angle of −179.0 (2)° in one molecule and 73.2 (2)° in the other. In one molecule there is a short N—H⋯O contact that generates an S(5) ring motif. In the crystal, N—H⋯O interactions generate R ₂ ²(8) graph-set motifs and C—H⋯O interactions generate R ₂ ²(10) and R ₂ ²(14) graph-set motifs. C—H⋯π interactions also occur.

Related literature

For the biological importance of diazepanes, see: Wlodarczyk et al. (2005 ▶); Gopalakrishnan et al. (2007 ▶). For a related structure, see: Kumar et al. (2009 ▶). For puckering parameters, see: Cremer & Pople (1975 ▶). For graph-set notation, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₂₀H₂₂N₂O₃
M _r = 338.40
Triclinic,
a = 9.5352 (3) Å
b = 14.8809 (4) Å
c = 15.0800 (4) Å
α = 61.650 (1)°
β = 82.153 (2)°
γ = 71.344 (2)°
V = 1783.86 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 K
0.30 × 0.30 × 0.25 mm

Data collection

Bruker Kappa APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ▶) T _min = 0.975, T _max = 0.979
39936 measured reflections
9437 independent reflections
6221 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.181
S = 1.15
9437 reflections
465 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); 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 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812017084/pv2527sup1.cif

e-68-o1525-sup1.cif^{(27.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812017084/pv2527Isup2.hkl

e-68-o1525-Isup2.hkl^{(461.5KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812017084/pv2527Isup3.cml

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

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

Cg1 and Cg2 are the centroids of the C33–C38 and C26–C31 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O2	0.85 (2)	2.45 (2)	2.776 (2)	104 (2)
N2—H2⋯O6ⁱ	0.85 (2)	2.26 (2)	3.091 (1)	170 (2)
N4—H4A⋯O3ⁱⁱ	0.85 (2)	2.14 (2)	2.983 (1)	169 (2)
C2—H2B⋯O2ⁱⁱⁱ	0.97	2.53	3.233 (2)	130
C39—H39A⋯O5^iv	0.97	2.48	3.355 (2)	150
C9—H9⋯Cg1^v	0.93	2.89	3.735 (3)	152
C16—H16⋯Cg2^vi	0.93	2.91	3.712 (1)	146

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

Acknowledgments

GJ and KS thank Dr Babu Varghese, SAIF, IIT, Chennai, India, for the X-ray intensity data collection and Dr V. Murugan, Head of the Department of Physics, RKM Vivekananda College, Chennai, India, for providing facilities in the department to carry out this work.

supplementary crystallographic information

Comment

The title compound belongs to an important class of heterocyclic compounds that have widespread applications from pharmaceuticals (Wlodarczyk et al., 2005) to biology (Gopalakrishnan et al., 2007).

In the title structure there are two crystallographically independent molecules (1 and 2) in an asymmetric unit (Fig. 1 and Fig. 2, respectively). The central diazepane rings (C4/C5/C12/C19/C20/N1/N2) and (C24/C25/C32/C39/C40/N3/N4) in the molecule 1 and 2 form dihedral angles of 71.6 (4)°, 40.3 (5)° and 75.9 (5)°, 58.6 (7)° with the neighbouring benzene rings (C6–C11), (C13–C18) and (C26–C31), (C33–C38), respectively. The dihedral angles between the pairs of benzene rings (C6–C11), (C13–C18) and (C26–C31), (C33–C38) are 54.8 (7)° and 58.4 (6)°, respectively. The sum of the bond angles around the atoms N₂ (362°) and N₄ (359.8°) of the diazepane rings indicate sp² hybridization, whereas the other N atoms, [N₁ (328.6°) and N₃ (331.2°)] indicate sp³ hybridization.

The atoms O3 and O6 deviate by 0.685 (14) Å and 0.498 (13) Å from the least square plane of the diazepane rings (C4/C5/C12/C19/C20/N1/N2) and (C24/C25/C32/C39/C40/N3/N4), respectively. The ethyl carboxylate groups exhibit significant conformational difference between the two molecules as reflected by the orientation of the carbonyl O-atoms and the torsion angles of C1—C2—O1—C3 is -179.0 (2)° for molecule 1 and C21—C22—O4—C23 is 73.2 (2)° in molecule 2. The conformational differences in the two molecules of the asymmetric unit of the title compound are evident in Fig. 3.

The diazepane rings (C4/C5/C12/C19/C20/N1/N2) and (C24/C25/C32/C39/C40/N3/N4) adopt chair conformations with puckering parameters (Cremer & Pople, 1975) Q₂ = 0.382 (2) Å, Q₃ = 0.678 (2) Å, φ₂ = 180.4 (2)°, φ₃ = 359.71 (14)° and Q₂ = 0.333 (2) Å, Q₃ = 0.670 (2) Å, φ₂ = 182.9 (3)°, φ₃ = 2.44 (14)°, respectively. The title compound exhibits structural similarities with another reported structure (Kumar et al., 2009).

The crystal packing is stabilized by intramolecular N–H···O, intermolecular N–H···O, C–H···O and C–H···π interactions (Table 1). The N2–H2···O2, N2–H2···O6ⁱ, N2–H4A···O3ⁱⁱ, C2–H2B···O2ⁱⁱⁱ and C39–H39B···O5^iv hydrogen bonds generates S(5) ring motif, dimers R²₂(8), R²₂(10) and R²₂(14) graphset motifs, respectively (Bernstein, et al., 1995). The crystal packing is further stabilized by C9—H9···Cg1^v and C16—H16···Cg2^vi interactions where Cg1 is center of gravity of (C33–C38) ring and Cg2 is center of gravity of (C26–C31) ring (Fig. 4; symmetry codes are given in Table 1)

Experimental

In a typical reaction, powdered ethyl 4-oxo-2,6-diphenyl piperidine- 3-carboxylate hydrochloride (2 g) was dissolved in an ice cold conc. H₂SO₄ (10 ml) in chloroform (5 ml) placed in a conical flask equipped with a magnetic stirrer. After the complete dissolution, the temperature of the solution was brought to 298 K. Sodium azide (600 mg) was added in portions over a period of 20 minutes with vigorous stirring. After the addition was over, the solution was poured slowly on to crushed ice with vigorous stirring, and the PH was adjusted to 8.0 using 4 N sodium hydroxide and extracted with chloroform. The combined organic layer was dried over sodium sulfate and evaporated to get the crude product which was purified by recrystallization from benzene and ethanol (1:1) to afford colourless prisms of the title compound.