N′-[(E)-2-Chlorobenzylidene]-2-(6-methoxynaphthalen-2-yl)propanohydrazide

In the title compound, C21H19ClN2O2, the benzene ring and the naphthalene ring system are oriented at a dihedral angle of 65.24 (10)°. In the crystal, N—H⋯O, C—H⋯N and C—H⋯O hydrogen bonds link the molecules, forming chains along the b-axis direction. Further C—H⋯O hydrogen bonds link the chains, forming corrugated sheets lying parallel to (10-1).

In the title compound, C 21 H 19 ClN 2 O 2 , the benzene ring and the naphthalene ring system are oriented at a dihedral angle of 65.24 (10) . In the crystal, N-HÁ Á ÁO, C-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds link the molecules, forming chains along the b-axis direction. Further C-HÁ Á ÁO hydrogen bonds link the chains, forming corrugated sheets lying parallel to (101).
The support of NSF-MRI grant No. 1228232 for the purchase of the diffractometer is gratefully acknowledged.

Comment
Naproxen ((+)-(S)-2-(6-methoxynaphthalen-2-yl)propanoic acid), among many non-steroidal anti-inflammatory drugs (NSAIDs), is used mainly in the treatment of pain, rehumatiod and inflammatory diseases (Merlet et al., 2013). It was reported that the presence of a carboxylic acid group in the parent drug leads to many undesirable side-effects such as gastrointestinal toxicity and ulceration (Uzgören-Baran et al., 2012;Tozkoparan et al., 2012). Recently, it was found that masking the carboxylic acid residue in the parent drug of NSAIDs led to safer pro-drug profiles and enhanced the chromophore efficacy (Koopaei et al., 2013). On the other hand, hydrazide-hydrazone scaffold compounds have been found to possess significant anti-inflammatory effects (Almasirad et al., 2005;Almasirad et al., 2006). Based on these findings the title compound was designed to be a hydrazone profile incorporating the Naproxen core structure without a carboxylic acid substituent. °, respectively. In (I), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, the N-H···O and C-H···N hydrogen bonds link the molecules, forming chains along the b-axis (Table 1 and Fig. 2). However, sensible C-H···O contacts are also present that link molecules into chains along c and extend the packing along the c axis.

Experimental
A mixture of 1 mmol (244 mg) Naproxen acid hydrazide [2-(6-methoxy-2-naphthyl)propanehydrazide] and 1 mmol (141 mg) 2-chlorobenzaldehyde was refluxed in 30 ml ethanol for 5hr in the presence of a few catalytic drops of glacial acetic acid. The mixture was cooled and separated, the solid filtered off, dried under vacuum and recrytallized from ethanol to furnish white crystals in a good quality suitable for X-ray diffraction. Mp 488-451 K.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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 Cl1