Ethyl 2-diethylamino-4-oxo-3,5-diphenyl-4,5-dihydro-3H-pyrrolo[3,2-d]pyrimidine-7-carboxylate

In the title compound, C25H26N4O3, the two fused pyrrolo[3,2-d]pyrimidine rings form a dihedral angle of 3.7 (2)°. The two substituent phenyl rings are twisted with respect to the pyrrole and pyrimidine rings, making dihedral angles of 57.2 (2) and 69.0 (2)°, respectively. The ethyl and ethoxy groups are disordered over two positions; the site occupancies are 0.53 (1) and 0.47 (1) for ethyl, and 0.63 (1) and 0.37 (1) for ethoxy. The crystal packing features C—H⋯O hydrogen bonds.

In the title compound, C 25 H 26 N 4 O 3 , the two fused pyrrolo[3,2d]pyrimidine rings form a dihedral angle of 3.7 (2) . The two substituent phenyl rings are twisted with respect to the pyrrole and pyrimidine rings, making dihedral angles of 57.2 (2) and 69.0 (2) , respectively. The ethyl and ethoxy groups are disordered over two positions; the site occupancies are 0.53 (1) and 0.47 (1) for ethyl, and 0.63 (1) and 0.37 (1) for ethoxy. The crystal packing features C-HÁ Á ÁO hydrogen bonds.

Experimental
The title compound was obtained in good yield via aza-Wittig reaction. Crystals suitable for single-crystal X-ray diffraction were obtained by recrystallization from a mixture of ethanol and dichloromethane (1:1 v/v) at room temperature.

Refinement
All H atoms were located in difference maps and treated as riding atoms with C-H = 0.93 Å, U iso =1.2U eq (C) for Csp 2 , C-H = 0.97 Å, U iso = 1.2U eq (C) for CH 2 , C-H = 0.96 Å, U iso = 1.5U eq (C) for CH 3 . N-H = 0.86 Å, U iso = 1.2U eq (N) for NH. Fig. 1. The molecular structure of the title compound showing the atom-labeling scheme with displacement ellipsoids drawn at the 30% probability level.

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 Rfactors(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.