(E)-2-(4-Methoxyphenyl)-N-(2-pyridyl)-3-(2-pyridylamino)acrylamide

In the title compound, C20H18N4O2, the aminoacrylamide group makes a dihedral angles of 4.0 (1)° with the amino-bound pyridyl ring and 15.66 (12)° with the amide-bound pyridyl ring. The dihedral angle between the aminoacrylamide group and the pendant 4-methoxyphenyl group is 71.22 (9)°. In the crystal structure, N—H⋯N hydrogen bonds and C—H⋯O and C—H⋯N interactions help to establish the packing. Intramolecular C—H⋯O and C—H⋯(N,O) contacts also occur.

In the title compound, C 20 H 18 N 4 O 2 , the aminoacrylamide group makes a dihedral angles of 4.0 (1) with the aminobound pyridyl ring and 15.66 (12) with the amide-bound pyridyl ring. The dihedral angle between the aminoacrylamide group and the pendant 4-methoxyphenyl group is 71.22 (9) . In the crystal structure, N-HÁ Á ÁN hydrogen bonds and C-HÁ Á ÁO and C-HÁ Á ÁN interactions help to establish the packing. Intramolecular C-HÁ Á ÁO and C-HÁ Á Á(N,O) contacts also occur.

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 et al., 2007(Xiao et al., , 2008. We herein report the crystal structure of the title compound, (I).
As shown in Fig. 1, the title compound is an enamine containing a functional group of amide moiety. The title compound consists of an aminoacrylamide moiety and three aromatic ring fragments. The aminoacrylamide moiety, C8, C9, C15, N1, N3 and O2, is nearly coplanar with a mean deviation of 0.023 Å, defined as plane I; C10 to C14 and N2 forms a plane with a mean deviation of 0.005 Å, defined as plane II; C16 to C20 and N4 forms a plane with a mean deviation of 0.008 Å, defined as plane III; C2 to C7 forms the fourth plane with a mean deviation of 0.005 Å, defined as plane IV. Plane II, plane III and plane IV make a dihedral angle of 4.018 (8), 15.66 (12) and 71.22 (9) ° with plane I, respectively. The bond distance C8-C9 [1.359 (5) Å] falls in the range of a typical double bond, and C9-N1 bond [1.352 (4) 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 C8-C9 double bond. For the same reason, we speculate that the p orbital of N1 is also conjugated with pyridyl group (plane II) and the p orbital of N3 is conjugated with both pyridyl group (plane III) and carboxyl group (C15=O2). All other double bonds and single bonds in the molecule fall in normal range of bond lengths.
The first fraction gave a Z-isomer, and the second fraction, after partial solvent evaporation, furnished colourless blocks of (I) suitable for single-crystal structure determination.
supplementary materials sup-2 Figures Fig. 1. The molecular structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 30% probability level.