Crystal structure of N-[(2-hydroxynaphthalen-1-yl)(4-methylphenyl)methyl]acetamide

In the title molecule, C20H19NO2, the naphthalene ring system subtends a dihedral angle of 82.50 (7)° with the benzene ring and an intramolecular N—H⋯O hydrogen bond closes an S(6) ring. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, which generate C(8) chains propagating in the [010] direction. The crystal structure also features weak π–π interactions [centroid–centroid separation = 3.7246 (10) Å].

Supporting information for this paper is available from the IUCr electronic archives (Reference: HB7375).

S1. Comment
1-Amidoalkyl-2-naphthol scaffolds are of significant medicinal relevance since they can be converted into hypertensive and bradycardiac active 1-aminoalkyl-2-naphthols by amine hydrolysis reactions [Schleiss et al., 2008]. As part of our studies in this area, we now describe the synthesis and structure of the title compound, (I).
The conformation of (I), together with the atom-numbering scheme, is shown in Fig. 1. In the structure, all bond lengths are comparable with those in previously reported structures (Mosslemin et al., 2007, NizamMohideen et al., 2009. Atom

S2. Experimental
The compound N-[(phenyl)-(2-hydroxy-naphthalen-1-yl)-methyl]acetamide was synthesized by using benzaldehyde, 2naphthol and acetamide by using Cp2ZrCl2 as a catalyst at room temperature. A mixture of 2-naphthol (1 mmol), benzaldehyde (1 mmol), acetamide (1.2 mmol) and zirconocene dichloride (20 mol%) was stirred in ethylene dichloride (5 ml) at room temperature for 10 h. After completion of reaction, as indicated by TLC, the reaction mixture was quenched in cold water. The obtained crude solid was filtered and purified by column chromatography on silica gel (Merck. 60-120 mesh, ethyl acetate: hexane)to afford the pure product in 72% yield. The identity of the compound was ascertained on the basis of FTIR, 1HNMR and 13CNMR spectroscopy as well as by mass spectrometry. The physical and spectroscopic data are consistent with the proposed structure and are in harmony with the literature values (Shaterian et al., 2008 153.43,139.67, 135.80, 132.64, 129.72, 129.08,128.86, 126.92,126.36, 123.53,122.98, 119.18, 118.82which is in agreement with the proposed structure. The Mass spectrum MS (EI): of this compound displayed the molecular ion peak at m/z = 306 (M+) which is in agreement with the proposed structure.

S3. Refinement
All H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.93-0.98 A; and with U iso (H) = 1.2U eq (C), except for the methyl groups where U iso (H) = 1.5U eq (C).

Figure 1
The molecular configuration of (I). Displacement ellipsoids are drawn at the 30% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.