Crystal structure of ethyl 2-(4-chlorophenyl)-3-cyclopentyl-4-oxo-1-propyl­imidazolidine-5-carboxylate

Mohamed Ali Tabarki; Youssef Ben Smida; Abderrahmen Guesmi; Rafâa Besbes

doi:10.1107/S2056989015015364

. 2015 Aug 22;71(Pt 9):o682–o683. doi: 10.1107/S2056989015015364

Crystal structure of ethyl 2-(4-chlorophenyl)-3-cyclopentyl-4-oxo-1-propylimidazolidine-5-carboxylate

Mohamed Ali Tabarki ^a, Youssef Ben Smida ^b,^*, Abderrahmen Guesmi ^b,^c, Rafâa Besbes ^a

PMCID: PMC4555374 PMID: 26396903

Abstract

The title compound, C₂₀H₂₇ClN₂O₃, was obtained via an original synthesis method. The central heterocyclic ring adopts a shallow envelope conformation, with the N atom bearing the cyclopentane ring as the flap [deviation from the other atoms = 0.442 (2) Å]. The cyclopentane ring adopts a twisted conformation about one of the C_N—C bonds: the exocyclic C—N bond adopts an equatorial orientation. The dihedral angles between the central ring (all atoms) and the pendant five- and six-membered rings are 10.3 (2) and 87.76 (14)°, respectively. In the crystal, C—H⋯O interactions link the molecules into [011] chains. A weak C—H⋯Cl interaction links the chains into (100) sheets. A mechanism for the cyclization reaction is proposed.

Keywords: crystal structure, synthesis, aziridine rearrangement, C—H⋯O and C—H⋯O interactions

Related literature

For background to the biological properties of imidazolidin-4-one rings, see: Chambel et al. (2006 ▸); Vale et al. (2008a ▸,b ▸,c ▸); Gomes et al. (2004 ▸); Araujo et al. (2005 ▸); Qin et al. (2009 ▸). For imidazolidin-4-one rings in Diels–Alder reactions, see: Lin et al. (2013 ▸). For the synthesis and mechanistic studies, see: Gomes et al. (2006 ▸); Zhang et al. (2008 ▸). graphic file with name e-71-0o682-scheme1.jpg

Experimental

Crystal data

C₂₀H₂₇ClN₂O₃
M _r = 378.89
Triclinic,
a = 9.083 (7) Å
b = 11.201 (6) Å
c = 11.846 (6) Å
α = 117.75 (4)°
β = 90.49 (5)°
γ = 104.08 (6)°
V = 1024.1 (11) Å³
Z = 2
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 298 K
0.4 × 0.3 × 0.2 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
6270 measured reflections
4439 independent reflections
2533 reflections with I > 2σ(I)
R _int = 0.024
2 standard reflections every 120 reflections intensity decay: 4%

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.180
S = 0.99
4439 reflections
295 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: CAD-4 EXPRESS (Duisenberg, 1992 ▸; Macíček & Yordanov, 1992 ▸); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▸); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▸); software used to prepare material for publication: WinGX (Farrugia, 2012 ▸) and publCIF (Westrip, 2010 ▸).

Supplementary Material

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989015015364/hb7486sup1.cif

e-71-0o682-sup1.cif^{(27KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015015364/hb7486Isup2.hkl

e-71-0o682-Isup2.hkl^{(213.1KB, hkl)}

Click here for additional data file.^{(7.6KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015015364/hb7486Isup3.cml

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

20 27 2 3 . DOI: 10.1107/S2056989015015364/hb7486fig1.tif

Synthesis protocol of C₂₀H₂₇ClN₂O₃.

Click here for additional data file.^{(1.5MB, tif)}

. DOI: 10.1107/S2056989015015364/hb7486fig2.tif

Perspective view of the title compound showing 50% displacement ellipsoids.

Click here for additional data file.^{(1.5MB, tif)}

20 27 2 3 . DOI: 10.1107/S2056989015015364/hb7486fig3.tif

Unit cell projection of C₂₀H₂₇ClN₂O₃ showing two molecules per cell.

CCDC reference: 1419261

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

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C10H2O1ⁱ	1.00(2)	2.50(3)	3.454(4)	160(2)
C3H12O3ⁱⁱ	0.99(4)	2.59(4)	3.439(5)	143(3)
C16H16BCl1ⁱⁱⁱ	0.97	2.80	3.662(6)	148

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

Acknowledgments

Financial support from the Ministry of Higher Education, Scientific Research and Technology of Tunisia is gratefully acknowledged. The authors are grateful to Professor Mohamed Faouzi Zid from the Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, for the data collection.

supplementary crystallographic information

S1. comment

The imidazolidin-4-one rings are of major interest and constitute a very important class of heterocyclic compounds because of their presence in several biologically active synthetic products (Chambel et al. 2006; Vale et al. 2008a) and their use as high antimalarial drugs (Vale et al. 2008b&c). These products exhibit also antibacterial activity (Gomes et al. 2004; Araujo et al. 2005) and inhibit binding of VCAM-1 to VLA-4 (Qin et al. 2009). On the other hand, imidazolidnione was used as organocatalyst for Diels-Alder reactions (Lin et al.2013).

In the present work we have developed an efficient strategy for the synthesis of 1-cyclopenty-2-parachlorophenyl-3-propyl-5-ethoxycarbonylimidazolidin-4-one (I) (Fig.1) via ring expansion of aziridine-2-carboxylate upon reaction with propylisocyanate. It should be mentioned that in a similar protocol, Gomes et al. (2006) report that aziridines rearrange under the effect of heating or radiation and transform into azomethines. The latter reacts subsequently on various electrophiles systems.

A result similar to one described by Zhang et al.(2008), but the authors did not explain the formation of the compounds obtained. To explain the formation of the imidazolidin-4-one we based on work that was performed by Gomes et al. (2006) and in which the authors suggest that aziridines rearrange under the effect of heating or irradiation and become an azomethine. The latter reacts subsequently on various electrophile systems. In our case, the attack of the isocyanate by the carbanion of azomethine, formed upon the refluxing in toluene aziridine, adequately explains obtaining imidazolidin-4-one after cyclization of the intermediate formed.

S2. Experimental

S2.1. Synthesis and crystallization

To a solution of ethyl 3-(4-chlorophenyl)-1-cyclopentylaziridine-2-carboxylate (2.20 mmol) in toluene (10 ml) under nitrogen atmosphere, were added n-Propylisocyanate (2.64 mmol). The mixture was refluxed during 20 hours. After completeness of the reaction, the mixture was concentrated under reduced pressure and the residue was purified by silica gel column chromatography using a mixture of n-hexane / EtOAc (5:5) as eluent to afford colourless prisms of the studied compound.

S2.2. Refinement

Hydrogen atoms were treated by a mixture of independent and constrained refinement. In fact hydrogen atoms from H1 to H15 were located in the difference Fourier Map. The others H atoms were located geometrically and refined using a riding model.