Ethyl 2-[6-(4-methylbenzoyl)-7-phenyl-2,3-dihydro-1H-pyrrolizin-5-yl]-2-oxoacetate

In the title compound, C25H23NO4, the pyrrolizine ring is approximately planar with an r.m.s deviation from planarity of 0.0053 Å, while the fused dihydropyrrolizine ring adopts an envelope conformation with the C atom connected to two CH2 as the flap. The dihedral angles between the fused ring system and the phenyl and methylbenzoyl rings are 41.65 (11) and 66.30 (8)°, respectively. In the crystal, weak C—H⋯O hydrogen bonds and C—H⋯π interactions occur. One molecule is linked to five adjacent ones through eight hydrogen bonds, forming a three-dimensional network.

In the title compound, C 25 H 23 NO 4 , the pyrrolizine ring is approximately planar with an r.m.s deviation from planarity of 0.0053 Å , while the fused dihydropyrrolizine ring adopts an envelope conformation with the C atom connected to two CH 2 as the flap. The dihedral angles between the fused ring system and the phenyl and methylbenzoyl rings are 41.65 (11) and 66.30 (8) , respectively. In the crystal, weak C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions occur. One molecule is linked to five adjacent ones through eight hydrogen bonds, forming a three-dimensional network.
The torsion angle of O1/C9/C10/O2 was 131.5 (4)°. As a result, three side chains of ring A arranged themselves like propeller due to steric.
In the crystal, a series of weak intermolecular C-H···O (Table 1)
A solution of ethyl oxalyl monochloride in anhydrous CH 2 Cl 2 was added. The mixture was stirred for 4 h at room temperature, and cooled to 273 K, an aqueous solution of HCl(w/w10%) was then added and the resulting solution was stirred for 1 h. After addition of water to form a clear aqueous layer, the organic layer was separated and dried(anhydrous Na 2 SO 4 ). Then the solution was evaporated under reduced pressure and purified by chromatography on silica gel column, eluting with a petroleum ether/acetone mixture (2:1) to give 65% yield of light yellow solid. The purity of the title compound was verified by elemental analysis: calculated for C 25 H 23 NO 4 : C 74.80, H 5.77, N 3.49; found C 65.72, H 4.39, N 3.83. EI-MS m/z: 402 (M+H) + .
The crystal appropriate for X-ray data collection was obtained from acetone solution at room temperature after two days.

Refinement
All H atoms were placed in geometically idealized positions and constrained to ride on their parent atoms with C-H distances of 0.93(0.97 for CH 2 )Å for CH, and U iso (H) = 1.2(1.5 for CH3)U eq (C). Four H atoms taking part in the hydrogen-bonds can be found on the difference Fourier maps although the position of H20B was not perfect.   The C-H···π interaction, dashed lines. Non-essential H atoms are omitted for clarity. Symmetry code: (i) -x, -y, -z.  (2) 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.