1-Ethoxymethyl-5-methyl-9-phenyl-6,7,8,9-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepine-2,4(3H,5H)-dione

The title compound, C17H22N4O3, comprises a 1,4-diazepine ring in a twist-boat conformation fused to a pyrimidine ring. The dihedral angle between the pyrimidine and phenyl rings is 80.8 (1)°. The crystal packing features N—H⋯O and C—H⋯O hydrogen bonds.

The title compound, C 17 H 22 N 4 O 3 , comprises a 1,4-diazepine ring in a twist-boat conformation fused to a pyrimidine ring. The dihedral angle between the pyrimidine and phenyl rings is 80.8 (1) . The crystal packing features N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds.

Comment
The title compound ( Fig. 1) belongs to a class having pyrimidodiazepine scaffold which in recent years has exhibited a range of biological activities such as antitumor agents (Insuasty et al., 2008;Chen et al., 2012), HIV-integrase inhibitors (Ferreira et al., 2009) and receptor tyrosine kinase inhibitors (Gracias et al., 2008). The title compound is gained during the structural modification work of our previously reported HIV-1 reverse transcriptase inhibitor (Wang et al., 2006). The main goal of this modification is to enhance the physicochemical properties and the flexibility of the seven-membered ring fused to the pyrimidine ring.
In the title compound, the dihedral angle between the phenyl ring and the pyrimidine ring is 80.8 (1)°. The diazepine ring exhibits a twist-boat conformation. To make a clear description of this boat conformation, the C4, C6, N3 and N4 atoms are regarded as coplanar, so that the C2, C7 and C5 atoms lie at the same side of the plane.

Refinement
H atoms were positioned geometrically, with C-H = 0.93 Å for aryl, 0.97 Å for the methylene, and 0.96 Å for the methyl H atoms, N-H = 0.93 Å. U iso (H) = 1.5U eq (C) for the methyl groups, 1.2U eq (C) for methylene, and 0.07U eq (N).      (7) 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.3598 (