(Z)-Ethyl 2-(4-chlorophenyl)-3-[(2,4-difluorophenyl)amino]prop-2-enoate

In the title compound, C17H14ClF2NO2, the aminoacryloyloxy group makes dihedral angles of 47.55 (11)° with the 4-chlorophenyl group and 8.74 (12)° with the difluorophenyl group; the dihedral angle between the rings is 52.32 (11)°. The structure of the title compound reveals a Z configuration with respect to the C=C double bond in the aminoacrylate fragment. A bifurcated intramolecular N—H⋯(O,F) hydrogen bond occurs. In the crystal, molecules are linked into chains by C—H⋯O hydrogen bonds.

In the title compound, C 17 H 14 ClF 2 NO 2 , the aminoacryloyloxy group makes dihedral angles of 47.55 (11) with the 4-chlorophenyl group and 8.74 (12) with the difluorophenyl group; the dihedral angle between the rings is 52.32 (11) . The structure of the title compound reveals a Z configuration with respect to the C C double bond in the aminoacrylate fragment. A bifurcated intramolecular N-HÁ Á Á(O,F) hydrogen bond occurs. In the crystal, molecules are linked into chains by C-HÁ Á ÁO hydrogen bonds.

Related literature
For background to Schiff bases, see: You & Zhu, 2006. For applications of enamines, see: Xiao et al. (2007Xiao et al. ( , 2008a Table 1 Hydrogen-bond geometry (Å , ).  Comment A 2-aryl-3-arylaminoacrylate contains characteristic N-C═C bond and is therefore identified as enamine. It is well known that Schiff base harbors an N═C-C bond, which indicates that an enamine is the tautomeric isomer of the correspond Schiff base. Enamines, like Schiff bases (You & Zhu, 2006), show good antimicrobial activities (Xiao et al., 2007;Xiao et al., 2008a), especially against bacterium. On the other hand, an enamine is the key intermediate for anticancer agents, 3-arylquinolone (Xiao et al., 2008b) and3-arylquinoline (Xiao et al., 2008c). In a continuation of our work on the structural characterization of enamine derivatives, we report herein the crystal structure of the title compound, (I).
The bond length of C13-N1 (1.344 (4) Å) is shorter than standard C-N single bond (1.48 Å) but longer than C-N double bond (1.28 Å), indicating that the p orbital of N1 is conjugated with the π molecular orbital of C13-C14 double bond. For the same reason, C1-N1 (1.394 (4) Å) is single bond with some double-bond character. The stereochemistry of the double bond in aminoacrylate moiety was assigned as (E)-configuration based on X-ray crystallography ( Fig. 1) of the title compound.

Experimental
Equimolar quantities (6 mmol) of ethyl 2-(4-chlorophenyl)-3-oxopropanoate (1.36 g) and 2,4-difluorobenzenamine (0.77 g) in absolute alcohol (18 ml) were heated at 344-354 K for 2 h. The excess solvent was removed under reduced pressure. The residue was purified by a flash chromatography with EtOAc-petrolum ether (1:6, v/v) 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.

Refinement
The H atom bonded to N1 was located in a difference Fourier map. All other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C-H = 0.93, 0.96 and 0.97 Å for the aromatic, CH 3 and CH 2 type H atoms, respectively. U iso = 1.2U eq (parent atoms) were assigned for aromatic and CH 2 type H-atoms and 1.5U eq (parent atoms) for CH 3 type H-atoms.