(Z)-Ethyl 3-(2,4-difluoro­anilino)-2-(4-methoxy­phen­yl)acrylate

Zhu-Ping Xiao; He-Ying Xiao

doi:10.1107/S1600536808036982

. 2008 Nov 20;64(Pt 12):o2371. doi: 10.1107/S1600536808036982

(Z)-Ethyl 3-(2,4-difluoroanilino)-2-(4-methoxyphenyl)acrylate

Zhu-Ping Xiao ^a,^*, He-Ying Xiao ^a

PMCID: PMC2959944 PMID: 21581343

Abstract

The title compound, C₁₈H₁₇F₂NO₃, consists of three individually planar subunits, namely two benzene rings and one aminoacrylate group. The aminoacrylate group forms dihedral angles of 5.92 (7) and 50.21 (6)° with the difluoro and methoxy benzene rings, respectively. The dihedral angle between the two benzene rings is 55.25 (7)°. The molecules exhibit intramolecular N—H⋯O and N—H⋯F interactions and form a three-dimensional network via intermolecular C—H⋯O and C—H⋯π hydrogen bonds.

Related literature

For general background, see: Xiao, Fang et al. (2008 ▶); Xiao, Li et al. (2008 ▶); Xiao, Xue et al. (2007 ▶). For related structures, see: Xiao, Li, Shi et al. (2008 ▶); Xiao, Lv et al. (2008 ▶); Xiao, Fang et al. (2007 ▶).

Experimental

Crystal data

C₁₈H₁₇F₂NO₃
M _r = 333.33
Monoclinic,
a = 17.295 (4) Å
b = 7.2940 (15) Å
c = 14.233 (3) Å
β = 113.73 (3)°
V = 1643.7 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 298 (2) K
0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.969, T _max = 0.989
3108 measured reflections
2974 independent reflections
1889 reflections with I > 2σ(I)
R _int = 0.016

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.156
S = 1.02
2974 reflections
224 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; 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: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808036982/bq2102sup1.cif

e-64-o2371-sup1.cif^{(19.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808036982/bq2102Isup2.hkl

e-64-o2371-Isup2.hkl^{(146KB, 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
C6—H6⋯O1ⁱ	0.93	2.51	3.280 (3)	140
C18—H18C⋯Cg1ⁱⁱ	0.96	2.92	3.631	132
N1—H1⋯F1	0.88 (2)	2.31 (2)	2.678 (2)	105.0 (18)
N1—H1⋯O1	0.88 (2)	2.02 (2)	2.678 (3)	131 (2)

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Symmetry codes: (i) Inline graphic ; (ii) . Cg1 is the centroid of C7–C12 ring.

Acknowledgments

The work was financed by a grant (No. JSDXKYZZ0801) from Jishou University for talent introduction, China.

supplementary crystallographic information

Comment

An enamine, a tautomer of a Schiff base, shows a high similarity to the corresponding Schiff base in chemical structure which shows diverse biological activities. Our recent work affirmed that enamine, like Schiff base, exhibited high antibacterial activity (Xiao, Xue et al., 2007; Xiao, Fang et al., 2008; Xiao, Li et al., 2008). Meanwhile, an enamine is the key mediate for anticancer agents, 3-arylquinolone and 3-arylquinoline (Xiao, Li et al. 2008; Xiao, Lv et al., 2008; Xiao, Fang et al.,2008). We herein report the crystal structure of the title compound, (I), an enamine.

As shown in Fig. 1, (I) is structurally divided into three subunits, and each moiety forms a plane, namely, C1 to C6 forms a plane with the mean deviation of 0.0015 Å, defined as plane I; C7 to C12 forms a plane with the mean deviation of 0.0035 Å, defined as plane II; N1, C13, C14, C15, O1 and O2 is nearly coplanar with the mean deviation of 0.0371 Å, defined as plane III. Plane III make a dihedral angle with plane I and plane II of 5.921 (74) and 50.207 (56) °, while the dihedral angle between plane I and plane II is 55.247 (72) °. The bond distance C13—C14 (1.360 (3) Å) falls in the range of a typical double bond, and C13—N1 bond (1.343 (3) Å) is shorter than the standard C—N single bond (1.48 Å), but longer than a C—N double bond (1.28 Å). This clearly indicates that the p orbital of N1 is conjugated with the π molecular orbital of C13—C14 double bond. All other double bonds and single bonds in the molecule fall in normal range of bond lengths.

The molecule is stabilized by intramolecular interactions N1—H1···O1 and N1—H1···F1 (Table 1), and form one-dimensional infinite chains via intermolecular hydrogen bonds C6—H6···O1 (Table 1). These chains are interconnected via weak C18—H18C···π (centroid of C7-C12 ring) interactions (Table 1 and Fig. 2).

Experimental

Equimolar quantities (6 mmol) of ethyl 2-(4-methoxyphenyl)-3- oxopropanoate (1.33 g) and 2,4-difluorobenzenamine (0.77 g) in absolute alcohol (18 ml) were heated at 344–354 K for 1.5 h. The excess solvent was removed under reduced pressure. The residue was purified by a flash chromatography with EtOAc-petrolum ether to afford two fractions. The second fraction gave a E-isomer, and the first fraction, after partial solvent evaporated, furnished colorless blocks of (I) suitable for single-crystal structure determination.