Ethyl 2-(7-oxo-3,5-diphenyl-1,4-diazepan-2-yl)acetate

In the title compound, C21H24N2O3, the diazepane ring adopts a chair conformation. The central diazepane ring forms dihedral angles 67.80 (7) and 72.29 (5)° with the two benzene rings. The ethoxycarbonyl group is disordered over two conformations with site-occupancy factors of 0.643 (5) and 0.357 (5). In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops.

In the title compound, C 21 H 24 N 2 O 3 , the diazepane ring adopts a chair conformation. The central diazepane ring forms dihedral angles 67.80 (7) and 72.29 (5) with the two benzene rings. The ethoxycarbonyl group is disordered over two conformations with site-occupancy factors of 0.643 (5) and 0.357 (5). In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds generate R 2 2 (8) loops.

Comment
The 1,4-diazepane derivatives are of considerable importance due to their wide spectrum of biological activities (Hirokawa et al., 1998).
H 2 SO 4 placed in a conical flask equipped with magnetic stirrer. After the complete dissolution, the temperature of the solution was brought to 298 K. Sodium azide (600 mg) was added in portions over a period of 20 minutes with vigorous stirring. The solution was then poured slowly on to crushed ice with vigorous stirring, and the pH was adjusted at approximately 8.0 using 4 N sodium hydroxide solution and extracted with chloroform. The combined organic layer was dried over sodium sulfate and evaporated to get the crude product. The crude product was purified by recrystallization from benzene and ethanol (1:1) to afford colourless prismatic crystals of the title compound suitable for X-ray crystallographic studies.

Figure 1
The molecular structure of the title compound with the atom numbering scheme, displacement ellipsoids are drawn at 30% probability level. H-atoms are present as small spheres of arbitary radius. The minor fraction of the disordered ethoxy carbonyl moiety has been represented by broken bonds.

Figure 2
The crystal packing of the title compound viewed down the a axis, showing hydrogen bonds resulting in R 2 2 (8) graph-set ring motif. H-atoms not involved in hydrogen bonds have been excluded for clarity. 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 Occ. (