4-(4-Methoxyphenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile

In the title compound, C20H17N3O4, the central pyran ring adopts a boat conformation with the O atom and diagonally opposite C atoms displaced by 0.1171 (1) and 0.1791 (1) Å, respectively, from the mean plane defined by the other four atoms. The coplanar atoms of the pyran ring and the methoxybenzene ring are nearly perpendicular, as evidenced by the dihedral angle 87.01 (1)°. The amine H atom forms an intramolecular N—H⋯O(nitro) hydrogen bond. In the crystal, molecules are linked into dimeric aggregates by N—H⋯O(nitro) hydrogen bonds, generating an R 2 2(12) graph-set motif.

In the title compound, C 20 H 17 N 3 O 4 , the central pyran ring adopts a boat conformation with the O atom and diagonally opposite C atoms displaced by 0.1171 (1) and 0.1791 (1) Å , respectively, from the mean plane defined by the other four atoms. The coplanar atoms of the pyran ring and the methoxybenzene ring are nearly perpendicular, as evidenced by the dihedral angle 87.01 (1) . The amine H atom forms an intramolecular N-HÁ Á ÁO(nitro) hydrogen bond. In the crystal, molecules are linked into dimeric aggregates by N-HÁ Á ÁO(nitro) hydrogen bonds, generating an R 2 2 (12) graph-set motif.
In the title compound, Fig. 1, the six-membered central pyran ring adopts a boat conformation as evidenced by the puckering parameters q 2 = 0.1713 (16) Å, θ = 98.1 (5)°, φ = 3.5 (6)° (Cremer & Pople, 1975). The dihedral angle between the methoxybenzene ring and the flat part of the pyran ring is 87.01 (1)° which means that the methoxybenzene ring is nearly perpendicular to the pyran ring. The acetonitrile group is almost coplanar with the plane of the pyrazole ring [the N3-C21-C2-C1 torsion angle is 174.04 (16)  In the crystal structure, N2-H2···O2 hydrogen bonds link molecules into dimeric pairs, Table 1. Each of these pairs generate a graph set motif of R 2 2 (12) (Bernstein et al., 1995), Fig. 2. In addition, there is a N-H···O intramolecular interaction which stabilizes the structure.

Experimental
A mixture of benzoylacetonitrile (1.0 mmol), 4-methoxy aldehyde (1.0 mmol), Et 3 N (1.0 mmol) and EtOH (10 ml) were taken in 50 ml round bottom flask. The reaction mixture was stirred at room temperature for 5-10 min. Then Nmethyl-1-(methylthio)-2-nitroethenamine was added into the reaction mixture followed by refluxing at 353 K. The consumption of starting material was monitored by TLC. After 90 min, the solid product was filtered and washed with diethyl ether (5 ml) and dried under vacuum in 92% yield; M.pt: 481 K.

Refinement
H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.98 Å and N-H = 0.86 Å, and with U iso = 1.2U eq (C, N) for N, CH 2 and CH H atoms and U iso = 1.5U eq (C) for CH 3 H atoms.

Special details
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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.