1-Benzyl-1,4-diazepan-5-one

The title compound, C12H16N2O, is a diazepane intermediate that can be used as an inhibitor of human nitric oxide synthesis. In the molecule, the seven-membered ring has a chair-like conformation and the two rings are approximately perpendicular to one another, with a C—N—C—C torsion angle of 77.8 (4)°. Intermolecular N—H⋯O hydrogen bonds link the molecules into dimers around a centre of symmetry, with C—H⋯O interactions linking the dimers into infinite sheets.

The title compound, C 12 H 16 N 2 O, is a diazepane intermediate that can be used as an inhibitor of human nitric oxide synthesis. In the molecule, the seven-membered ring has a chair-like conformation and the two rings are approximately perpendicular to one another, with a C-N-C-C torsion angle of 77.8 (4) . Intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules into dimers around a centre of symmetry, with C-HÁ Á ÁO interactions linking the dimers into infinite sheets.

Comment
The title compound is a 1-substituted 1,4-diazepan-5-one; an important class of heterocyclic compounds that have widespread applications from pharmaceuticals (Wlodarczyk et al., 2006) to biology (Gopalakrishnan et al., 2007). As part of our studies in this area, we report herein the synthesis and crystal structure of the title compound, (I).
In the molecule (Fig. 1) the 7-membered ring has a chair-like conformation with C1,C2,C3 and C4 forming the planar seat of the chair and N2 out of the plane on one side and N1-C5 out of the plane on the other side. The two rings are approximately perpendicular to one another with a C3-N2-C6-C7 torsion angle of 77.8 (4)°. Intermolecular N-H···O hydrogen bonds link the molecules into dimers around a center of symmetry with C-H···O interactions linking the dimers into infinite sheets (Fig. 2).
Experimental 1-Benzyl-piperidin-4-one (18.9 g,0.1 mol) was added into a stirred mixture of sulfuric acid (40 ml) and dichloromethane (80 ml) at 273 K. Then, at 273 K, sodium azide (32.5 g,0.5 mol) was cautiously added over a period of 3 h and the resulting mixture was stirred for 1 h with the temperature kept at approximately 278 K. Then ice (1 kg) was quickly added and the solution was alkalized with ammonium hydroxide (15%,200 mL) to pH=11. The organic layer was separated with the water fraction extracted with dichloromethane (3x100mL). The organic extracts were combined,dried over NaSO 4 , and concentrated in vacuo. The residue was recrystallized from EtOAc to give the title compound, (I) (yield: 13.0 g, 65%).
Crystals of (I) suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH) and 0.93 Å fro aromatic carbons and 0.97 Å for all others, and constrained to ride on their parent atoms, with U iso (H) = xUeq(C,N), where x = 1.5 for methyl H, and x = 1.2 for all other H atoms. Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. 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 > 2sigma(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.