Ethyl 3,5-dimethyl-1H-pyrrole-2-carboxyl­ate

Cláudia T Arranja; Manuela Ramos Silva; Ana Matos Beja; Ana F P V Ferreira; Abílio J F N Sobral

doi:10.1107/S1600536808029929

. 2008 Sep 24;64(Pt 10):o1989. doi: 10.1107/S1600536808029929

Ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate

Cláudia T Arranja ^a, Manuela Ramos Silva ^b,^*, Ana Matos Beja ^b, Ana F P V Ferreira ^a, Abílio J F N Sobral ^a

PMCID: PMC2959273 PMID: 21201188

Abstract

In the title compound, C₉H₁₃NO₂, there are two independent molecules per asymmetric unit. The molecules are very similar and almost planar, with the ethoxycarbonyl group anti to the pyrrole N atom. The two independent molecules are joined into dimeric units by strong hydrogen bonds between NH groups and carbonyl O atoms.

Related literature

For general background, see: Bonnett (1995 ▶, 2000 ▶). For related structures, see: Paixão et al. (2002 ▶), Ramos Silva et al. (2002 ▶); Sobral & Rocha Gonsalves (2001 ▶).

Experimental

Crystal data

C₉H₁₃NO₂
M _r = 167.20
Triclinic,
a = 8.1357 (2) Å
b = 10.5568 (2) Å
c = 12.1428 (2) Å
α = 101.5451 (13)°
β = 97.8791 (14)°
γ = 110.4821 (14)°
V = 932.52 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 (2) K
0.25 × 0.20 × 0.15 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2000 ▶) T _min = 0.899, T _max = 0.987
20370 measured reflections
4456 independent reflections
2368 reflections with I > 2σ(I)
R _int = 0.028

Refinement

R[F ² > 2σ(F ²)] = 0.052
wR(F ²) = 0.182
S = 1.03
4456 reflections
223 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808029929/bt2791sup1.cif

e-64-o1989-sup1.cif^{(20.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808029929/bt2791Isup2.hkl

e-64-o1989-Isup2.hkl^{(218.3KB, hkl)}

Additional supplementary materials: 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—H1⋯O4	0.86	2.02	2.857 (2)	166
N2—H2⋯O2	0.86	2.00	2.834 (2)	163

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Acknowledgments

This work was supported by Fundação para a Ciência e a Tecnologia (FCT) under project POCI/AMB/55281/2004.

supplementary crystallographic information

Comment

Photodynamic therapy (PDT) is a developing method for the treatment of carcinomas and sarcomas. It consists in a selective absorption of a photosensitizer in a tumor, followed by irradiation with light of a selected wavelength, originating tumor necrosis. The fewer side effects of this therapeutic method when compared to chemotherapy and radiotherapy have prompted the search for new and more efficient photosensitizers, namely porphyrins (Bonnett, 1995, 2000). Pyrroles are building blocks for the synthesis of porphyrins and following our previous structural studies on pyrrole chemistry (Sobral & Rocha Gonsalves, 2001; Ramos Silva et al., 2002; Paixão et al., 2002) we present here the title compound ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate, (I), Fig. 1. There are two independent molecules per asymmetric unit. The two molecules are very similar and almost planar with the angle between molecular planes being 3.87 (5)°. The molecules show an eclipsed conformation, when viewed along the C1—C7 direction, with the ethoxycarbonylgroup anti to the pyrrole N atom. The molecules are grouped in dimers by strong hydrogen bonds between N—H groups and carbonyl O atoms (Fig.1, Table 1). The dimers stack in planes approximately 5 Å apart (Fig.2).

Experimental

The ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate was prepared by a Knorr-type reaction from the condensation of acetylacetone and ethyl oximinoacetoacetate.