Ethyl 3,4-dimethyl-1H-pyrrole-2-carboxyl­ate

Wu, W.-N.; Li, X.-X.; Wang, Q.-F.; Li, Y.-W.

doi:10.1107/S160053681003179X

organic compounds

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Volume 66| Part 9| September 2010| Page o2309

https://doi.org/10.1107/S160053681003179X

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Ethyl 3,4-dimethyl-1H-pyrrole-2-carboxylate

Wei-Na Wu,^a ^* Xiao-Xia Li,^b Qiu-Fen Wang ^a and Yan-Wei Li ^a

^aDepartment of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000, People's Republic of China, and ^bInstitute of Functional Materials, Jiangxi University of Finance & Economics, Nanchang 330013, People's Republic of China
^*Correspondence e-mail: wuwn08@hpu.edu.cn

(Received 16 July 2010; accepted 8 August 2010; online 18 August 2010)

The non-H atoms of the title compound, C₉H₁₃NO₂, are almost coplanar (r.m.s. deviation = 0.0358 Å). Weak intermolecular N—H⋯O hydrogen bonds link the molecules into zigzag chains along the b axis with graph-set motif C(5). The chains are further linked into a three-dimensional network by C—H⋯O hydrogen bonds and C—H⋯π interactions.

Related literature

Schiff bases containing pyrrole units have been extensively investigated due to their excellent coordination abilities, see: Wu et al. (2003 ). For our studies on bis(pyrrol-2-yl-methyleneamine) ligands, see: Wang et al., (2008 ). For a similar structure, 5-formyl-3,4-dimethyl-1H-pyrrole-2-carboxylate, see Wu et al. (2009 ). For the preparation, see: Helms et al. (1992 ). For graph-set motifs, see: Etter et al. (1990 ).

Experimental

Crystal data

C₉H₁₃NO₂
M_r = 167.20
Monoclinic, P 2₁ /c
a = 7.7485 (2) Å
b = 7.0611 (2) Å
c = 17.2167 (5) Å
β = 95.103 (2)°
V = 938.24 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.28 × 0.26 × 0.18 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2007 ) T_min = 0.977, T_max = 0.985
8174 measured reflections
2146 independent reflections
1579 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.136
S = 1.04
2146 reflections
112 parameters
H-atom parameters constrained
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the N1,C1–C4 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.86	2.13	2.9264 (16)	154
C4—H4⋯Cg1ⁱⁱ	0.93	2.92	3.7520 (17)	149
C9—H9A⋯Cg1ⁱⁱⁱ	0.96	2.86	3.650 (2)	141
Symmetry codes: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x, y+1, z.

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S160053681003179X/fb2205sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681003179X/fb2205Isup2.hkl

checkCIF report

Comment top

Schiff bases containing pyrrole units have been extensively investigated due to their excellent coordination abilities (Wu et al., 2003). As a part of our studies on bis(pyrrol-2-yl-methyleneamine) ligands (Wang et al., 2008), the crystal structure of the title compound is reported here.

The non-hydrogen atoms of the title molecule (Fig. 1) are situated in a fair plane (r.m.s. deviation of the non-hydrogen atoms being 0.0358 Å). In the crystal structure, the molecules are linked by weak intermolecular N—H···O hydrogen bonds, forming zig-zag chains with the graph-set motifs C(5) (Etter & MacDonald, 1990). The chains are extended along the b axis (Tab. 1, Fig. 2, Fig. 3). The structure is also stabilized by the C—H···O hydrogen bonds (Tab. 1) and C—H···π-electron ring interactions (Tab. 1).

Related literature top

Schiff bases containing pyrrole units have been extensively investigated due to their excellent coordination abilities, see: Wu et al. (2003). For our studies on bis(pyrrol-2-yl-methyleneamine) ligands, see: Wang et al., (2008). For a similar structure, 5-formyl-3,4-dimethyl-1H-pyrrole-2-carboxylate, see Wu et al. (2009). For the preparation, see: Helms et al. (1992). For graph-set motifs, see: Etter & MacDonald (1990);

Experimental top

The title compound was prepared according to Helms et al. (1992). Acetic acid (114 ml) was placed in a 1-L round-bottom flask and heated to 85 °C. Sodium acetate (31.09 g), 27.54 g of sodium 2-methyl-3-oxo-l-butene-1-oxide, 37.20 g of diethyl 2-(hydroxyimino)malonate, and a solution of 47 ml of acetic acid in 19.6 ml of H₂O were then added in the respective order. The reaction temperature was raised to 95 °C, and 43.26 g of Zn-dust was added over 45 min while maintaining the temperature between 95 and 110 °C. After the addition of Zn-dust had been completed, the mixture was stirred while keeping its temperature at 110 °C for further 45 min. The reaction mixture was then poured into 500 ml of ice water. The obtained solid was filtered, washed with water and subsequently dissolved in dichloromethane. The solution was washed with saturated sodium hydrogencarbonate, dried with anhydrous sodium sulfate and then the solvent was removed under reduced pressure. The crude product was purified by column chromatography on a silica gel [R_f = 0.68, petroleum ether-ethyl acetate (100:1) as an eluent] to yield 4.82 g (13%) of the title compound. Colourless block crystals [average size: 0.25× 0.25 × 0.20 mm] were obtained by slow evaporation of the ethyl acetate solution at room temperature.

Structure description top

Schiff bases containing pyrrole units have been extensively investigated due to their excellent coordination abilities, see: Wu et al. (2003). For our studies on bis(pyrrol-2-yl-methyleneamine) ligands, see: Wang et al., (2008). For a similar structure, 5-formyl-3,4-dimethyl-1H-pyrrole-2-carboxylate, see Wu et al. (2009). For the preparation, see: Helms et al. (1992). For graph-set motifs, see: Etter & MacDonald (1990);

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The title molecule with the displacement ellipsoids shown at the 50% probability level.
	Fig. 2. The crystal packing for the title compound via N—H···O hydrogen bonds shown as the dashed lines.
	Fig. 3. A view showing zig-zag chains with the graph-set motifs C(5) pertinent to the N—H···O hydrogen bonds (the dashed lines) in the title structure. The atoms not involved in this motif have been omitted for clarity.

Ethyl 3,4-dimethyl-1H-pyrrole-2-carboxylate top

Crystal data top

C₉H₁₃NO₂	F(000) = 360
M_r = 167.20	D_x = 1.184 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3131 reflections
a = 7.7485 (2) Å	θ = 2.4–24.8°
b = 7.0611 (2) Å	µ = 0.08 mm⁻¹
c = 17.2167 (5) Å	T = 296 K
β = 95.103 (2)°	Block, colourless
V = 938.24 (5) Å³	0.28 × 0.26 × 0.18 mm
Z = 4

Data collection top

Bruker SMART APEX CCD diffractometer	2146 independent reflections
Radiation source: fine-focus sealed tube	1579 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
φ and ω scans	θ_max = 27.5°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2007)	h = −9→10
T_min = 0.977, T_max = 0.985	k = −9→9
8174 measured reflections	l = −22→22

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.044	Hydrogen site location: difference Fourier map
wR(F²) = 0.136	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0691P)² + 0.1432P] where P = (F_o² + 2F_c²)/3
2146 reflections	(Δ/σ)_max < 0.001
112 parameters	Δρ_max = 0.21 e Å⁻³
0 restraints	Δρ_min = −0.17 e Å⁻³
49 constraints

Crystal data top

C₉H₁₃NO₂	V = 938.24 (5) Å³
M_r = 167.20	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 7.7485 (2) Å	µ = 0.08 mm⁻¹
b = 7.0611 (2) Å	T = 296 K
c = 17.2167 (5) Å	0.28 × 0.26 × 0.18 mm
β = 95.103 (2)°

Data collection top

Bruker SMART APEX CCD diffractometer	2146 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2007)	1579 reflections with I > 2σ(I)
T_min = 0.977, T_max = 0.985	R_int = 0.019
8174 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.136	H-atom parameters constrained
S = 1.04	Δρ_max = 0.21 e Å⁻³
2146 reflections	Δρ_min = −0.17 e Å⁻³
112 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O2	0.14704 (13)	0.48430 (14)	0.11453 (6)	0.0534 (3)
O1	−0.00527 (14)	0.33077 (15)	0.19987 (7)	0.0615 (3)
N1	0.24389 (16)	0.04205 (17)	0.20998 (7)	0.0498 (3)
H1	0.1597	0.0168	0.2377	0.060*
C2	0.41028 (18)	0.1886 (2)	0.12961 (8)	0.0463 (4)
C7	0.12075 (18)	0.34064 (19)	0.16247 (8)	0.0445 (3)
C1	0.25621 (17)	0.20054 (19)	0.16438 (8)	0.0422 (3)
C8	0.0178 (2)	0.6323 (2)	0.10833 (10)	0.0582 (4)
H8A	0.0125	0.6946	0.1583	0.070*
H8B	−0.0953	0.5796	0.0923	0.070*
C4	0.3843 (2)	−0.0672 (2)	0.20438 (10)	0.0561 (4)
H4	0.4060	−0.1820	0.2299	0.067*
C3	0.49035 (19)	0.0178 (2)	0.15508 (9)	0.0521 (4)
C9	0.0697 (3)	0.7705 (3)	0.04886 (11)	0.0686 (5)
H9A	0.1837	0.8179	0.0644	0.103*
H9B	−0.0111	0.8738	0.0447	0.103*
H9C	0.0699	0.7085	−0.0007	0.103*
C5	0.4845 (2)	0.3287 (3)	0.07667 (11)	0.0702 (5)
H5A	0.3973	0.3650	0.0363	0.105*
H5B	0.5806	0.2725	0.0536	0.105*
H5C	0.5234	0.4386	0.1060	0.105*
C6	0.6620 (2)	−0.0563 (3)	0.13353 (13)	0.0784 (6)
H6A	0.7528	0.0278	0.1533	0.118*
H6B	0.6604	−0.0640	0.0778	0.118*
H6C	0.6820	−0.1799	0.1557	0.118*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0535 (6)	0.0449 (6)	0.0639 (7)	0.0109 (4)	0.0178 (5)	0.0096 (5)
O1	0.0585 (7)	0.0564 (7)	0.0742 (8)	0.0072 (5)	0.0314 (6)	0.0035 (5)
N1	0.0523 (7)	0.0466 (7)	0.0523 (7)	0.0007 (5)	0.0151 (6)	0.0061 (5)
C2	0.0450 (7)	0.0479 (8)	0.0469 (8)	0.0013 (6)	0.0092 (6)	0.0019 (6)
C7	0.0464 (7)	0.0416 (7)	0.0467 (8)	−0.0002 (6)	0.0107 (6)	−0.0038 (6)
C1	0.0433 (7)	0.0403 (7)	0.0440 (7)	0.0001 (5)	0.0091 (6)	0.0021 (6)
C8	0.0595 (9)	0.0451 (8)	0.0711 (10)	0.0133 (7)	0.0119 (8)	0.0018 (8)
C4	0.0615 (9)	0.0468 (8)	0.0595 (9)	0.0088 (7)	0.0025 (7)	0.0079 (7)
C3	0.0462 (8)	0.0545 (9)	0.0560 (9)	0.0084 (6)	0.0059 (7)	−0.0004 (7)
C9	0.0832 (12)	0.0541 (10)	0.0685 (11)	0.0128 (9)	0.0066 (9)	0.0102 (9)
C5	0.0643 (10)	0.0732 (12)	0.0775 (12)	0.0024 (9)	0.0302 (9)	0.0191 (9)
C6	0.0571 (10)	0.0842 (13)	0.0950 (14)	0.0260 (9)	0.0134 (10)	0.0026 (11)

Geometric parameters (Å, º) top

O2—C7	1.3347 (17)	C4—C3	1.371 (2)
O2—C8	1.4446 (17)	C4—H4	0.9300
O1—C7	1.2186 (17)	C3—C6	1.506 (2)
N1—C4	1.3440 (19)	C9—H9A	0.9600
N1—C1	1.3752 (17)	C9—H9B	0.9600
N1—H1	0.8600	C9—H9C	0.9600
C2—C1	1.3849 (19)	C5—H5A	0.9600
C2—C3	1.409 (2)	C5—H5B	0.9600
C2—C5	1.494 (2)	C5—H5C	0.9600
C7—C1	1.4406 (19)	C6—H6A	0.9600
C8—C9	1.495 (2)	C6—H6B	0.9600
C8—H8A	0.9700	C6—H6C	0.9600
C8—H8B	0.9700

C7—O2—C8	116.91 (12)	C4—C3—C2	107.21 (13)
C4—N1—C1	109.16 (12)	C4—C3—C6	126.27 (15)
C4—N1—H1	125.4	C2—C3—C6	126.51 (15)
C1—N1—H1	125.4	C8—C9—H9A	109.5
C1—C2—C3	106.86 (12)	C8—C9—H9B	109.5
C1—C2—C5	128.10 (13)	H9A—C9—H9B	109.5
C3—C2—C5	125.02 (13)	C8—C9—H9C	109.5
O1—C7—O2	122.94 (13)	H9A—C9—H9C	109.5
O1—C7—C1	124.41 (14)	H9B—C9—H9C	109.5
O2—C7—C1	112.65 (12)	C2—C5—H5A	109.5
N1—C1—C2	107.69 (12)	C2—C5—H5B	109.5
N1—C1—C7	118.98 (12)	H5A—C5—H5B	109.5
C2—C1—C7	133.32 (13)	C2—C5—H5C	109.5
O2—C8—C9	107.22 (13)	H5A—C5—H5C	109.5
O2—C8—H8A	110.3	H5B—C5—H5C	109.5
C9—C8—H8A	110.3	C3—C6—H6A	109.5
O2—C8—H8B	110.3	C3—C6—H6B	109.5
C9—C8—H8B	110.3	H6A—C6—H6B	109.5
H8A—C8—H8B	108.5	C3—C6—H6C	109.5
N1—C4—C3	109.09 (14)	H6A—C6—H6C	109.5
N1—C4—H4	125.5	H6B—C6—H6C	109.5
C3—C4—H4	125.5

C8—O2—C7—O1	0.1 (2)	O1—C7—C1—C2	−177.02 (15)
C8—O2—C7—C1	179.83 (13)	O2—C7—C1—C2	3.3 (2)
C4—N1—C1—C2	−0.19 (16)	C7—O2—C8—C9	−177.04 (13)
C4—N1—C1—C7	−178.84 (13)	C1—N1—C4—C3	−0.06 (18)
C3—C2—C1—N1	0.37 (16)	N1—C4—C3—C2	0.29 (18)
C5—C2—C1—N1	−178.16 (16)	N1—C4—C3—C6	179.24 (16)
C3—C2—C1—C7	178.74 (16)	C1—C2—C3—C4	−0.40 (17)
C5—C2—C1—C7	0.2 (3)	C5—C2—C3—C4	178.18 (16)
O1—C7—C1—N1	1.2 (2)	C1—C2—C3—C6	−179.35 (16)
O2—C7—C1—N1	−178.46 (12)	C5—C2—C3—C6	−0.8 (3)

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the N1,C1–C4 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.86	2.13	2.9264 (16)	154
C5—H5A···O2	0.96	2.60	2.962 (2)	103
C4—H4···Cg1ⁱⁱ	0.93	2.92	3.7520 (17)	149
C9—H9A···Cg1ⁱⁱⁱ	0.96	2.86	3.650 (2)	141

Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x+1, y−1/2, −z+1/2; (iii) x, y+1, z.

Experimental details

Crystal data
Chemical formula	C₉H₁₃NO₂
M_r	167.20
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	7.7485 (2), 7.0611 (2), 17.2167 (5)
β (°)	95.103 (2)
V (Å³)	938.24 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.28 × 0.26 × 0.18

Data collection
Diffractometer	Bruker SMART APEX CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2007)
T_min, T_max	0.977, 0.985
No. of measured, independent and observed [I > 2σ(I)] reflections	8174, 2146, 1579
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.136, 1.04
No. of reflections	2146
No. of parameters	112
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.17

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the N1,C1–C4 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.86	2.13	2.9264 (16)	153.5
C5—H5A···O2	0.96	2.60	2.962 (2)	102.8
C4—H4···Cg1ⁱⁱ	0.93	2.92	3.7520 (17)	149
C9—H9A···Cg1ⁱⁱⁱ	0.96	2.86	3.650 (2)	141

Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x+1, y−1/2, −z+1/2; (iii) x, y+1, z.

Acknowledgements

The authors are grateful for financial support by the Doctoral Foundation of Henan Polytechnic University (B2009–70 648364).

References

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