3-[(1-Bromonaphthalen-2-yl)methoxy]-5,5-dimethylcyclohex-2-enone

In the title compound, C19H19BrO2, the cyclohexenone ring adopts an envelope conformation with the C atom bearing the methyl substituents as the flap. In the crystal, weak π–π stacking is observed between parallel aromatic rings of adjacent molecules, the centroid–centroid distance being 3.694 (6) Å. The entire bromonaphthylmethyl unit is disordered over two orientations, with a site-occupancy ratio of 0.5214 (19):0.4786 (19).

In the title compound, C 19 H 19 BrO 2 , the cyclohexenone ring adopts an envelope conformation with the C atom bearing the methyl substituents as the flap. In the crystal, weakstacking is observed between parallel aromatic rings of adjacent molecules, the centroid-centroid distance being 3.694 (6) Å . The entire bromonaphthylmethyl unit is disordered over two orientations, with a site-occupancy ratio of 0.5214 (19):0.4786 (19).  In the title compound, C 19 H 19 BrO 2 , all the bond lengths and bond angles are within normal ranges. The cyclohexenone ring adopts an envelope conformation with the C atom bearing two methyl groups as the flap atom. All the atoms in the o-bromonaphthylmethyl group are disordered over two positions with site occupancy factors of 0.521 (2) and 0.479 (2).

Related literature
In the crystal structure, weak π-π stacking is observed between parallel aromatic rings of adjacent molecules, the centrods distance being 3.694 (6) Å.

Experimental
To a solution of 1-bromo-2-(bromomethyl)naphthalene (0.15 g, 0.5 mmol) and 5,5-dimethylcyclohexane-1,3-dione (0.14 g, 1.0 mmol) in DMF (3 ml) were added K 2 CO 3 (0.21 g, 1.5 mmol) and CuI (0.01 g, 0.05 mmol). The mixture was stirred at 373 K until a complete conversion. It was cooled to room temperature and added with water, then extracted with ethyl ether (5 ml × 3). The combined organic phases were concentrated under vacuum. The crude product was purified by column chromatography eluting with ethyl acetate/hexane (10-20%) to give the title compound with the yield of 32% (0.057 g, 0.16 mmol). Single crystals, suitable for X-ray diffraction analysis, were obtained by slow evaporation of the solvents from a chloroform-ethyl acetate (1:1 v/v) solution of the title compound.
The The bromonaphthalene moiety is disordered over two orientations, the site occupancies were refined to 0.5214 (19):0.4786 (19), the ADP of corresponding atoms in the disordered components were restrained as the same.  Molecular structure of the title compound with the disorder atoms, with displacement ellipsoids drawn at the 30% probability level.

Figure 2
Molecular structure of the title compound without the disorder atoms, with displacement ellipsoids drawn at the 30% probability level.  Crystal structure of the title compound with view along the a axis (disorder atoms have been omitted for clarity).

3-[(1-Bromonaphthalen-2-yl)methoxy]-5,5-dimethylcyclohex-2-enone
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.  (7)