6,11-Dihydrodibenz[b,e]oxepin-11-one

In the title compound, C14H10O2, the seven-membered oxepine ring adopts a twist-boat conformation with a dihedral angle between the mean planes of the two fused benzene rings of 42.0 (1)°. In the crystal, molecules are linked into chains propagating along the c axis by intermolecular C—H⋯O hydrogen bonds and the chains are arranged in layers parallel to (100).

In the title compound, C 14 H 10 O 2 , the seven-membered oxepine ring adopts a twist-boat conformation with a dihedral angle between the mean planes of the two fused benzene rings of 42.0 (1) . In the crystal, molecules are linked into chains propagating along the c axis by intermolecular C-HÁ Á ÁO hydrogen bonds and the chains are arranged in layers parallel to (100).
QNMHA thanks the University of Mysore for use of its research facilities. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.

Comment
The title compound is used as an intermediate for the synthesis of doxepin, which is a psychotropic agent with tricyclic antidepressant and anxiolytic properties. Doxepin is a tricyclic compound and displays a range of pharmacological actions including maintaining adrenergic innervation. Its mechanism of action is not fully understood, but it appears to block re-uptake of monoaminergic neurotransmitters into presynaptic terminals. It also possesses anticholinergic activity and modulates antagonism of histamine H(1)-and H(2)-receptors. The dibenz[b,e]oxepin nucleus constitutes the fundamental structure of many products with biological activity (Kumazawa et al., 1994). The dibenzo[c,e]thiepine derivatives (Truce et al., 1956) exhibit remarkable chiroptical properties (Tomascovic et al., 2000). The comparative NMR and IR spectral, X-ray structural and theoretical studies of eight related 6-arylidenedibenzo[b,e]thiepin-11-one-5,5-dioxides have been reported (Kolehmainen et al., 2007). In view of the importance of oxepines, this paper reports the crystal structure of the title compound.
The seven-membered oxepin ring adopts a twist-boat conformation with the dihedral angle between the mean planes of the two fused benzene rings measuring 42.0 (1)° (Fig. 1). This conformation is assisted by sp 3 hybridization of atoms C8 and O2 within the ring. The ketone oxygen atom (O1) lies in an equatorial position from the ring on opposite sides of the C8 and O2 atoms (C3-C2-C1-O1 = -19.1 (4)° and C13-C14-C1-O1 = 35.3 (4)°). Bond lengths and angles are all within expected ranges (Allen, 2002). The molecules are linked into chains propagating along the c-axis by C10-H10A···O1 intermolecular hydrogen bonds and the chains are arranged in layers parallel to the (100) (Fig. 2).

Experimental
The title compound was obtained as a gift sample from R. L. Fine Chem, Bangalore, India. The compound was used without further purification. X-ray quality crystals (m.p. 327-329 K) were obtained by slow evaporation from a methanol solution.

Refinement
All of the H atoms were placed in their calculated positions and then refined using the riding model with C-H = 0.95-0.99 Å, and with U iso (H) = 1.18-1.21U eq (C). Fig. 1. Molecular structure of the title compound, showing atom-labeling scheme and 50% probability displacement ellipsoids.