4-Acetyl-1H-pyrrole-2-carbaldehyde

Sun, T.; Xie, J.-W.; Zhao, R.-Y.; Zhu, A.-G.; Ge, Y.-Q.

doi:10.1107/S1600536812039153

organic compounds

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ISSN: 2056-9890

Volume 68| Part 10| October 2012| Page o2947

https://doi.org/10.1107/S1600536812039153

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4-Acetyl-1H-pyrrole-2-carbaldehyde

Tao Sun,^a Jia-Wei Xie,^a Ren-Ying Zhao,^a Ai-Guo Zhu ^a and Yan-Qing Ge ^a ^*

^aTaishan Medical University, Tai'an 271016, People's Republic of China
^*Correspondence e-mail: yqge@yahoo.cn

(Received 20 August 2012; accepted 13 September 2012; online 19 September 2012)

The title compound, C₇H₇NO₂, was synthesized via a one-pot Vilsmeier–Haack and subsequent Friedel–Crafts reaction. The pyrazole ring makes dihedral angles of 4.50 (9) and 2.06 (8)°, respectively, with the aldehyde and acetyl groups. In the crystal, classical N—H⋯O hydrogen bonds and weak C—H⋯O interactions assemble the molecules into a chain along the b axis.

Related literature

For the synthetic procedure, see: Ge et al. (2009 ). For related structures, see: Ge et al. (2011 ); Hao et al. (2012 ).

Experimental

Crystal data

C₇H₇NO₂
M_r = 137.14
Monoclinic, P 2₁ /n
a = 3.811 (5) Å
b = 13.219 (5) Å
c = 13.167 (5) Å
β = 95.602 (5)°
V = 660.2 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 293 K
0.15 × 0.13 × 0.10 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.541, T_max = 0.556
3752 measured reflections
1348 independent reflections
1010 reflections with I > 2σ(I)
R_int = 0.056

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.128
S = 1.04
1348 reflections
93 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O2ⁱ	0.86	2.11	2.876 (2)	148
C7—H7A⋯O1ⁱⁱ	0.96	2.54	3.453 (5)	159
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812039153/im2396sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812039153/im2396Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536812039153/im2396Isup3.cml

checkCIF report

Comment top

Synthesis of nitrogen-containing heterocyclic compounds has been a subject of great interest due to the wide application in agrochemical and pharmaceutical fields (Ge et al.; 2009, 2011). Some pyrrole derivatives which belong to this category exhibit interesting biological properties, such as anti-bacterial, anti-inflammatory, anti-oxidant, anti-tumor, anti-fungal, and immune suppressant activities. The title pyrazole (I) (Fig. 1) was synthesized in order to study its biological properties. (I) was screened for anticancer activities and found to be inactive. We report here the crystal structure of the title compound. In the title compound, C₇H₇NO₂, the pyrazole ring makes dihedral angles of 4.50 (9)° and 2.06 (8)°, respectively, with the aldehyde group and acetyl group. The crystal structure is determined by classical intermolecular N—H···O (H1A···O2 = 2.11 Å) hydrogen bonding and weak C—H···O (H7A···O1 = 2.54 Å) interactions, which assemble the molecules into a one-dimensional chain structure.

Related literature top

For the synthetic procedure, see: Ge et al. (2009). For related structures, see: Ge et al. (2011); Hao et al. (2012).

Experimental top

A solution of dimethylformamide (5.5 mmol) in 1,2-dichloroethane (10 ml) in a 3-necked flask was cooled in an ice bath. To the stirred and cooled solution was added a solution of oxalyl chloride (5.5 mmol) in 1,2-dichloroethane (10 ml) over a period of 10 min. The suspension of white solid was then allowed to stir at room temperature for 15 min. The suspension was cooled in ice and a solution of pyrrole (5 mmol) in 1.2-dichloroethane (10 ml) was added over 10 min. The light orange solution obtained was allowed to stir 15 min at room temperature.To this was added aluminium chloride (11 mmol), followed by acetyl chloride (5 mmol), rapidly and at room temperature. The mixture was stirred for 3 h. The mixture was then poured onto about 50 ml of ice and water, 50% aqueous sodium hydroxide (4 ml) was added, and the mixture was stirred rapidly for about 10 min. The mixture was than made slightly acidic with concentrated hydrochloric acid and the organic and aqueous layers were separated. The aqueous layer was extracted with ethyl ether. The organic extracts were washed with water, dried, filtered and concentrated. The final product was isolated by column chromatography on silica gel (yield 76%). Crystals of (I) suitable for X-ray diffraction were obtained by allowing a refluxed solution of the product in ethyl acetate (0.10 M) to cool slowly to room temperature (without temperature control) and allowing the solvent to evaporate for 3 d.

Structure description top

For the synthetic procedure, see: Ge et al. (2009). For related structures, see: Ge et al. (2011); Hao et al. (2012).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of compound, showing displacement ellipsoids drawn at the 30% probability level.
	Fig. 2. The one-dimensional infinite chain structure, which is formed by intermolecular N—H···O hydrogen bonding and weak C—H···O interactions.

4-Acetyl-1H-pyrrole-2-carbaldehyde top

Crystal data top

C₇H₇NO₂	F(000) = 288
M_r = 137.14	D_x = 1.380 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2yn	Cell parameters from 1324 reflections
a = 3.811 (5) Å	θ = 3.1–25.7°
b = 13.219 (5) Å	µ = 0.10 mm⁻¹
c = 13.167 (5) Å	T = 293 K
β = 95.602 (5)°	Block, colorless
V = 660.2 (9) Å³	0.15 × 0.13 × 0.10 mm
Z = 4

Data collection top

Bruker APEXII CCD area-detector diffractometer	1348 independent reflections
Radiation source: fine-focus sealed tube	1010 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.056
phi and ω scans	θ_max = 26.4°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −4→4
T_min = 0.541, T_max = 0.556	k = −15→16
3752 measured reflections	l = −12→16

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H-atom parameters constrained
wR(F²) = 0.128	w = 1/[σ²(F_o²) + (0.0703P)²] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
1348 reflections	Δρ_max = 0.20 e Å⁻³
93 parameters	Δρ_min = −0.14 e Å⁻³
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.031 (9)

Crystal data top

C₇H₇NO₂	V = 660.2 (9) Å³
M_r = 137.14	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 3.811 (5) Å	µ = 0.10 mm⁻¹
b = 13.219 (5) Å	T = 293 K
c = 13.167 (5) Å	0.15 × 0.13 × 0.10 mm
β = 95.602 (5)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	1348 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	1010 reflections with I > 2σ(I)
T_min = 0.541, T_max = 0.556	R_int = 0.056
3752 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.128	H-atom parameters constrained
S = 1.04	Δρ_max = 0.20 e Å⁻³
1348 reflections	Δρ_min = −0.14 e Å⁻³
93 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
N1	0.4828 (4)	0.16971 (9)	0.21257 (10)	0.0472 (4)
H1A	0.4131	0.1739	0.2726	0.057*
O2	0.7983 (4)	0.23425 (9)	−0.10389 (9)	0.0634 (4)
C4	0.5018 (4)	0.24663 (12)	0.14876 (11)	0.0448 (4)
H4	0.4423	0.3133	0.1619	0.054*
C6	0.6799 (4)	0.27169 (12)	−0.02967 (12)	0.0459 (4)
C2	0.5910 (4)	0.08234 (11)	0.16858 (11)	0.0452 (4)
O1	0.4742 (4)	−0.03023 (10)	0.29831 (10)	0.0777 (5)
C3	0.6811 (4)	0.10776 (11)	0.07349 (12)	0.0437 (4)
H3	0.7652	0.0638	0.0264	0.052*
C5	0.6236 (4)	0.21205 (11)	0.05991 (11)	0.0413 (4)
C7	0.5885 (6)	0.38131 (13)	−0.02795 (14)	0.0606 (5)
H7A	0.6548	0.4132	−0.0887	0.091*
H7B	0.7126	0.4126	0.0308	0.091*
H7C	0.3392	0.3887	−0.0248	0.091*
C1	0.5825 (5)	−0.01457 (13)	0.21628 (14)	0.0582 (5)
H1	0.6661	−0.0696	0.1819	0.070*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0623 (9)	0.0475 (8)	0.0331 (7)	−0.0014 (6)	0.0119 (6)	−0.0040 (6)
O2	0.0926 (10)	0.0596 (8)	0.0412 (7)	−0.0007 (6)	0.0225 (6)	−0.0005 (6)
C4	0.0576 (10)	0.0385 (8)	0.0390 (9)	0.0007 (7)	0.0082 (7)	−0.0040 (7)
C6	0.0535 (9)	0.0477 (9)	0.0366 (9)	−0.0042 (7)	0.0046 (7)	−0.0013 (7)
C2	0.0538 (10)	0.0432 (9)	0.0383 (9)	−0.0001 (7)	0.0026 (7)	−0.0017 (7)
O1	0.1213 (12)	0.0589 (9)	0.0546 (9)	−0.0035 (7)	0.0173 (8)	0.0133 (7)
C3	0.0503 (9)	0.0423 (9)	0.0389 (9)	0.0017 (7)	0.0065 (7)	−0.0067 (7)
C5	0.0467 (9)	0.0420 (9)	0.0356 (8)	−0.0020 (6)	0.0053 (6)	−0.0024 (6)
C7	0.0764 (12)	0.0480 (10)	0.0585 (11)	0.0044 (9)	0.0112 (9)	0.0073 (8)
C1	0.0797 (13)	0.0467 (10)	0.0480 (10)	−0.0001 (8)	0.0052 (9)	0.0011 (8)

Geometric parameters (Å, º) top

N1—C4	1.325 (2)	C2—C1	1.429 (2)
N1—C2	1.373 (2)	O1—C1	1.211 (2)
N1—H1A	0.8600	C3—C5	1.405 (2)
O2—C6	1.2207 (18)	C3—H3	0.9300
C4—C5	1.378 (2)	C7—H7A	0.9600
C4—H4	0.9300	C7—H7B	0.9600
C6—C5	1.452 (2)	C7—H7C	0.9600
C6—C7	1.491 (2)	C1—H1	0.9300
C2—C3	1.372 (2)

C4—N1—C2	109.91 (13)	C5—C3—H3	126.1
C4—N1—H1A	125.0	C4—C5—C3	106.19 (13)
C2—N1—H1A	125.0	C4—C5—C6	126.74 (14)
N1—C4—C5	109.11 (13)	C3—C5—C6	127.07 (13)
N1—C4—H4	125.4	C6—C7—H7A	109.5
C5—C4—H4	125.4	C6—C7—H7B	109.5
O2—C6—C5	121.72 (16)	H7A—C7—H7B	109.5
O2—C6—C7	120.76 (14)	C6—C7—H7C	109.5
C5—C6—C7	117.52 (14)	H7A—C7—H7C	109.5
C3—C2—N1	106.92 (14)	H7B—C7—H7C	109.5
C3—C2—C1	129.75 (15)	O1—C1—C2	124.74 (17)
N1—C2—C1	123.23 (15)	O1—C1—H1	117.6
C2—C3—C5	107.87 (13)	C2—C1—H1	117.6
C2—C3—H3	126.1

C2—N1—C4—C5	0.08 (18)	C2—C3—C5—C6	−179.38 (15)
C4—N1—C2—C3	0.20 (18)	O2—C6—C5—C4	177.98 (16)
C4—N1—C2—C1	−176.51 (16)	C7—C6—C5—C4	−1.8 (2)
N1—C2—C3—C5	−0.40 (17)	O2—C6—C5—C3	−2.2 (2)
C1—C2—C3—C5	176.02 (16)	C7—C6—C5—C3	177.96 (15)
N1—C4—C5—C3	−0.33 (17)	C3—C2—C1—O1	−174.36 (18)
N1—C4—C5—C6	179.50 (14)	N1—C2—C1—O1	1.5 (3)
C2—C3—C5—C4	0.45 (17)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O2ⁱ	0.86	2.11	2.876 (2)	148
C7—H7A···O1ⁱⁱ	0.96	2.54	3.453 (5)	159

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

Experimental details

Crystal data
Chemical formula	C₇H₇NO₂
M_r	137.14
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	293
a, b, c (Å)	3.811 (5), 13.219 (5), 13.167 (5)
β (°)	95.602 (5)
V (Å³)	660.2 (9)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.15 × 0.13 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD area-detector
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.541, 0.556
No. of measured, independent and observed [I > 2σ(I)] reflections	3752, 1348, 1010
R_int	0.056
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.128, 1.04
No. of reflections	1348
No. of parameters	93
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.14

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O2ⁱ	0.86	2.11	2.876 (2)	148.4
C7—H7A···O1ⁱⁱ	0.96	2.54	3.453 (5)	159.2

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

Acknowledgements

This study was supported by the Shandong Natural Science Foundation (No. ZR2012BL04).

References

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