Tetra­ethyl 1,1′-(ethane-1,2-di­yl)bis­(2,5-dimethyl-1H-pyrrole-3,4-dicarboxyl­ate)

Shi-Fan Wang; Chao Li; Shuai Chen

doi:10.1107/S1600536810044119

. 2010 Nov 6;66(Pt 12):o3047. doi: 10.1107/S1600536810044119

Tetraethyl 1,1′-(ethane-1,2-diyl)bis(2,5-dimethyl-1H-pyrrole-3,4-dicarboxylate)

Shi-Fan Wang ^a,^b,^*, Chao Li ^a, Shuai Chen ^a

PMCID: PMC3011439 PMID: 21589360

Abstract

The asymmetric unit of the title compound, C₂₆H₃₆N₂O₈, comprises two independent molecules. In each molecule, the two pyrrole rings are linked by a –CH₂CH₂– bridge, with dihedral angles between the two pyrrole rings of 14.5 (3) and 16.4 (3)° in the two molecules. Each pyrrole ring carries 2- and 5-methyl substituents and ethoxycarbonyl groups at the 3- and 5-positions.

Related literature

For background to the biological applications of bispyrrole and its derivatives, see: Dairi et al. (2006 ▶); Bordner & Rapoport (1965 ▶); Rapoport & Castagnoli (1962 ▶). For the synthesis and biological properties of pyrrole derivatives containing N-substituent groups, see: Banik et al. (2004 ▶); Sagyam et al. (2007 ▶). For details of the the Paal–Knorr condensation reaction, see Amarnath et al. (1991 ▶). For representative bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₂₆H₃₆N₂O₈
M _r = 504.57
Monoclinic,
a = 12.891 (3) Å
b = 13.743 (3) Å
c = 16.717 (3) Å
β = 113.350 (14)°
V = 2719.0 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 298 K
0.20 × 0.18 × 0.17 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.982, T _max = 0.985
5726 measured reflections
5726 independent reflections
3020 reflections with I > 2σ(I)
R _int = 0.000

Refinement

R[F ² > 2σ(F ²)] = 0.062
wR(F ²) = 0.194
S = 0.99
5726 reflections
663 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.29 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810044119/sj5043sup1.cif

e-66-o3047-sup1.cif^{(39.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810044119/sj5043Isup2.hkl

e-66-o3047-Isup2.hkl^{(280.3KB, hkl)}

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

Acknowledgments

This research was supported financially by the National Key Technology R&D Program of China (grant No. 2007BAI27B05).

supplementary crystallographic information

Comment

Bis-pyrrole and its derivatives play important roles in some bioactive pyrrole natural products, (Dairi et al., 2006; Bordner & Rapoport, 1965; Rapoport & Castagnoli, 1962). Recently, the synthesis of pyrrole derivatives with N-substituent groups aroused great interest because of their significant biological activity (Banik et al., 2004; Sagyam et al., 2007). As an intermediate for further synthesis of pyrrole derivatives containing N-substituent groups, we have prepared the title compound by the Paal-Knorr condensation reaction (Amarnath et al., 1991) and obtained its strcuture is reported here.

In the asymmetric unit of the title compound, Fig. 1, there are two independent molecules, A and B. The dihedral angle between the two pyrrole rings in one molecule is 14.5 (3)°, and that in the other molecule is 16.4 (3)°. All the bond lengths are within normal ranges (Allen et al., 1987).

Experimental

12.8 ml of ethyl acetoacetate (0.10 mol) and 2.28 g (0.10 mol) of sodium metal were added into 300 ml dry ether under stirring at room temperature. Then, the mixed solution was refluxed for 24 h till the Na was depleted. 100 ml dry ether solution contained 12.5 g (0.050 mol) I₂ was added dropwise. After all of the iodine solution had been added, the reaction mixture was refluxed for 12 h and then cooled to room temperature. The undissolved solid was filtered and the ether solution was evaporated to yield diacetyl butanedioic acid diethyl ester as a gray solid (8.64 g, 67%). 5.20 g (20 mmol) of diacetyl butanedioic acid diethyl ester and 0.60 g (10 mmol) of ethylenediamine were dissolved into the mixed solution of ethanol and acetic acid (v/v, 5:1). The mixture was then refluxed for 6 h and evaporated to remove the ethanol. The residue was poured into water to give the title compound as a white solid (4.91 g, 97%). A little of the solid was dissolved in mixed solvent of acetone-water (v/v, 20:1). After standing in air over a period of about five days, the acetone is evaporated, colourless crystals suitable for X-ray diffraction analysis were formed at the bottom of the vessel.