(3,6-Dimeth­oxy-2-naphth­yl)(4-fluoro­benzo­yl)methanone

Shoji Watanabe; Toyokazu Muto; Atsushi Nagasawa; Akiko Okamoto; Noriyuki Yonezawa

doi:10.1107/S1600536810006859

. 2010 Feb 27;66(Pt 3):o712. doi: 10.1107/S1600536810006859

(3,6-Dimethoxy-2-naphthyl)(4-fluorobenzoyl)methanone

Shoji Watanabe ^a, Toyokazu Muto ^a, Atsushi Nagasawa ^a, Akiko Okamoto ^a, Noriyuki Yonezawa ^a,^*

PMCID: PMC2983725 PMID: 21580450

Abstract

In the title compound, C₁₉H₁₅FO₃, the dihedral angle between the naphthalene ring system and the benzene ring is 62.93 (5)°. The bridging carbonyl C—C(=O)—C plane makes dihedral angles of 45.55 (6) and 28.62 (7)°, respectively, with the naphthalene ring system and the benzene ring. Weak intermolecular C—H⋯O hydrogen bonds and C—H⋯π interactions stabilize the crystal packing.

Related literature

For general background to the regioselective formation of peri-aroylnaphthalene compounds, see: Okamoto & Yonezawa (2009 ▶). For related structures, see: Hijikata et al. (2010 ▶); Mitsui et al. (2008 ▶); Nakaema et al. (2007 ▶, 2008 ▶); Watanabe et al. (2010a ▶,b ▶).

Experimental

Crystal data

C₁₉H₁₅FO₃
M _r = 310.31
Monoclinic,
a = 8.3690 (2) Å
b = 19.7603 (5) Å
c = 9.3897 (2) Å
β = 105.126 (2)°
V = 1499.01 (6) Å³
Z = 4
Cu Kα radiation
μ = 0.84 mm⁻¹
T = 193 K
0.55 × 0.50 × 0.45 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: numerical (NUMABS; Higashi, 1999 ▶) T _min = 0.657, T _max = 0.705
26258 measured reflections
2738 independent reflections
2530 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.090
S = 1.02
2738 reflections
211 parameters
H-atom parameters constrained
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.11 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 ▶); program(s) used to solve structure: SIR2004 (Burla et al., 2005 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810006859/bt5198sup1.cif

e-66-0o712-sup1.cif^{(19.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810006859/bt5198Isup2.hkl

e-66-0o712-Isup2.hkl^{(134.5KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C1–C5/C10 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C18—H18B⋯Cg1ⁱ	0.98	2.85	3.7479 (14)	152
C17—H17⋯O1ⁱⁱ	0.95	2.55	3.2930 (16)	136
C18—H18A⋯O3ⁱⁱⁱ	0.98	2.39	3.3603 (16)	169

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors would express their gratitude to professor Keiichi Noguchi for his technical advice. This work was partially supported by the Ogasawara Foundation for the Promotion of Science & Engineering, Tokyo, Japan.

supplementary crystallographic information

Comment

In the course of our study 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). The aroyl groups at the 1,8-positions of the naphthalene rings in these compounds are twisted almost perpendicularly but the benzene ring moieties of the aroyl groups tilt slightly toward the exo sides of the naphthalene rings.

Recently, we reported the structures of 1,8-diaroyl-2,7-dimethoxynaphthalenes, i. e., 1,8-bis(4-chlorobenzoyl)-2,7-dimethoxynaphthalene (Nakaema et al., 2007), bis(4-bromobenzoyl)(2,7-dimethoxynaphthalene-1,8-diyl)dimethanone (Watanabe et al., 2010a). In addition, the crystal structural analysis of 1-aroyl-2,7-dimethoxynaphthalenes, i. e., methyl 4-(2,7-dimethoxy-1-naphthoyl)benzoate (Hijikata et al., 2010) and 1-(4-nitorobenzoyl)-2,7-dimethoxynaphthalene (Watanabe et al. 2010b), also has revealed essentially the same non-coplanar structure as the 1,8-diaroylated naphthalenes.

Furthermore, the structure of 3-aroyl-2,7-dimetoxynaphthalenes such as 2-(4-chlorobenzoyl)-3,6-dimethoxynaphthalene (Nakaema et al., 2008), which are generally regarded to be thermodynamically more stable than the corresponding 1-positioned isomeric molecules, 1-(4-chlorobenzoyl)-2,7-dimethoxynaphthalene (Mitsui et al., 2008), has been also studied. As a part of our ongoing work on the formation reaction and the structure of the aroylated naphthalene derivatives, the synthesis and crystal structure of (I), a 3-monoaroylnaphthalene bearing fluoro group, is discussed in this report. (I) was prepared by electrophilic aromatic aroylation reaction of 2,7-dimethoxynaphthalene with 4-fluorobenzoic acid.

An ORTEPIII (Burnett & Johnson, 1996) plot of (I) is displayed in Fig. 1. The 4-fluorophenyl group is twisted away from the attached naphthalene ring. The dihedral angle between the best planes of the fluorophenyl ring (C12—C17) and the naphthalene ring (C1—C10) is 62.93 (5)°. The bridging carbonyl plane (O1—C11—C3—C12) makes relatively large dihedral angle of 45.55 (6)° with the naphthalene ring (C1—C10) [C4—C3—C11—O1 torsion angle = 43.90 (17)°], whereas it makes rather small one of 28.62 (7)° with 4-fluorophenyl ring (C12—C17) [O1—C11—C12—C17 torsion angle = 28.69 (18)°].

Molecules are linked by C—H···π interactions (Fig. 2). The methyl group acts as an hydrogen-bond donor and π system of the naphthalene ring [C1—C5/C10 ring (with centroid Cg1)] of an adjacent molecule acts as an accepter (C18—H18B···π).

The crystal packing is additionally stabilized by two types of intermolecular weak C—H···O hydrogen bondings: One is between the aromatic hydrogen (H17) at meta position to the F group, and the carbonyl oxygen (O1) (Fig.3, Table 1). The other is between an hydrogen (H18A) of the 2-methoxy group which is situated adjacent to the fluorophenyl group, and the ethereal oxygen (O3) of the 7-methoxy group in a neighboring molecule .

Experimental

The title compound was prepared by treatment of a mixture of 2,7-dimethoxynaphthalene (0.20 mmol) and 4-fluoroobenzoic acid (0.21 mmol) with phosphorus pentoxide–methanesulfonic acid mixture (P₂O₅–MsOH [1/10 w/w]; 0.44 ml) at 60°C for 24 hours followed by a typical work-up procedure (30% yield; Okamoto & Yonezawa, 2009). Colorless block single crystals suitable for X-ray diffraction were obtained by recrystallization from chloroform.