[2,7-Dibutoxy-8-(4-fluorobenzoyl)naphthalen-1-yl](4-fluorophenyl)methanone

In the title compound, C32H30F2O4, the benzene rings of the benzoyl groups make dihedral angles of 74.55 (6) and 74.39 (7)° with the naphthalene ring system. In the crystal, intra- and intermolecular C—H⋯π interactions are observed between the butoxy group and the aromatic rings. There are also C—H⋯F hydrogen bonds present that link the molecules into chains propagating along [010].

In the title compound, C 32 H 30 F 2 O 4 , the benzene rings of the benzoyl groups make dihedral angles of 74.55 (6) and 74.39 (7) with the naphthalene ring system. In the crystal, intra-and intermolecular C-HÁ Á Á interactions are observed between the butoxy group and the aromatic rings. There are also C-HÁ Á ÁF hydrogen bonds present that link the molecules into chains propagating along [010].  Table 1 Hydrogen-bond geometry (Å , ).

Related literature
Cg1 and Cg2 are the centroids of the C12-C17 and C5-C10 rings, respectively. In the course of our studies on electrophilic aromatic aroylation of 2,7-dimethoxynaphthalene, peri-aroylnaphthalene compounds have proven to be formed regioselectively with the aid of suitable acidic mediators (Okamoto & Yonezawa, 2009;Okamoto, Mitsui et al., 2011). In one application, the authors have integrated the resulting molecular unit to a poly(ether ketone) backbone via nucleophilic aromatic substitution polycondensation (Okamoto et al., 2012). The fashion, but the benzene ring moieties of the aroyl groups tilt slightly toward the exo sides of the naphthalene rings. As a part of our continuous studies on the molecular structures of this kind of homologous molecules, the X-ray crystal structure of the title compound is presented herein.
The molecular structure of the title compound is displayed in Fig. 1. Two benzoyl groups at the 1,8-positions of the naphthalene ring are situated in opposite directions, with an anti orientation. The benzene rings of the benzoyl groups make dihedral angles with the naphthalene ring system of 74.55 (6) and 74.39 (7)°, respectively. The dihedral angle between these benzene rings is 44.61 (8)°.
In the crystal structure, the molecular packing of the title compound is stabilized mainly by two types of C-H···π interactions: a) an intramolecular C-H···π interaction between the benzene ring of the aroyl group (C12-C17; Cg1) and one methylene H atom (H27B) of the butoxy group (C27-H27B···Cg1= 2.79 Å; Fig. 2 and Table 1); and b) an intermolecular C-H···π interaction between the centroid of the C5-C10 ring (Cg2) and one methylene H atom (H26A) of the butoxy group (C26-H26A···Cg2 i = 2.54 Å; Fig. 2 and Table 1). There is also a C-H···F hydrogen bond present (Table 1) that links the molecules to form chains propagating along the b axis direction.

Experimental
The title compound was prepared by treating a mixture of 2,7-dibutoxynaphthalene (3.0 mmol, 817 mg) and 4-fluorobenzoic acid (6.6 mmol, 924 mg) with a phosphorus pentoxide-methanesulfonic acid mixture (P 2 O 5 -MsOH [1/10 w/w] 13.2 ml). After the reaction mixture had been stirred at 333 K for 1 h, the mixture was poured into ice-cold water and extracted with CHCl 3 . The organic layer thus obtained was dried over anhydrous MgSO 4 . The solvent was removed under reduced pressure to give a cake. The crude product was purified by recrystallization from CHCl 3 -hexane (v/v = 1:2) Block-like colourless crystals of the title compound, suitable for X-ray diffraction analysis, were obtained by crystallization from hexane. Spectroscopic data for the title compound are available in the archived CIF.

Refinement
All the H atoms were included in calculated positions and treated as riding on their parent atoms: C-H = 0.95 (aromatic ), 0.98 (methyl), 0.99 (methylene) Å, with U iso (H) = 1.2U eq (C). The positions of methyl H atoms were rotationally optimized.      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.