cis-2-(4-Methoxyphenyl)-4-methyl-1,2-dihydronaphthalen-1-ol

The stereochemistry and regiochemistry of the title compound, C18H18O2, were determined by the X-ray analysis. There are two independent molecules in the asymmetric unit in which the dihedral angles between the benzene rings are 88.31 (4) and 86.27 (4)°. The cyclohexene rings are in half-chair conformations. In the crystal, O—H⋯O hydrogen bonds link alternating types of molecules into chains along [010] with graph-set C 2 2(4).

The stereochemistry and regiochemistry of the title compound, C 18 H 18 O 2 , were determined by the X-ray analysis. There are two independent molecules in the asymmetric unit in which the dihedral angles between the benzene rings are 88.31 (4) and 86.27 (4) . The cyclohexene rings are in halfchair conformations. In the crystal, O-HÁ Á ÁO hydrogen bonds link alternating types of molecules into chains along [010] with graph-set C 2 2 (4).

Comment
We have recently investigated the metal-catalyzed ring-opening reactions of oxanorbornadiene compounds (Jack et al., 2013). When expanding this reaction using a palladium catalyst, C1-methyl substituted oxanorbornadiene (I) (see Fig. 1) reacts with 4-methoxy-1-iodobenzene (II) in the presence of PdCl 2 (PPh 3 ) 2 , Zn, ZnCl 2 , Et 3 N in DMF, to give the ringopening product (III) as a single regio-and stereoisomer. The stereochemistry and regiochemistry of the product was determined by this single-crystal X-ray analysis. Although different regio-and stereoisomers could be formed, the only ring-opening product obtained was found to have a cis stereochemistry.
There are two independent molecules [A and B] in the asymmetric unit which are shown in Fig. 2 Fig. 3).

Refinement
Hydrogen atoms bonded to C atoms were placed in calculated positions with C-H distances ranging from 0.95-1.00 Å and included in the refinement in a riding-model approximation with U iso (H) = 1.2U eq (C) or 1.5U eq (C methyl ). H atoms bonded to O atoms were refined independently with isotropic displacement parameters.

Figure 1
The reaction scheme.  The asymmetric unit of the title compound showing 30% probability ellipsoids. The dashed line indicates a hydrogen bond.

Figure 3
Part of the crystal structure with hydrogen bonds shown as dashed lines.

cis-2-(4-Methoxyphenyl)-4-methyl-1,2-dihydronaphthalen-1-ol
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.  0.0305 (7) 0.0323 (7)