(5-Benzoyl-3,6-dimeth­oxy­naphthalen-2-yl)(phen­yl)methanone

Yuichi Kato; Atsushi Nagasawa; Kosuke Sasagawa; Akiko Okamoto; Noriyuki Yonezawa

doi:10.1107/S160053681101508X

. 2011 Apr 29;67(Pt 5):o1250. doi: 10.1107/S160053681101508X

(5-Benzoyl-3,6-dimethoxynaphthalen-2-yl)(phenyl)methanone

Yuichi Kato ^a, Atsushi Nagasawa ^a, Kosuke Sasagawa ^a, Akiko Okamoto ^a,^*, Noriyuki Yonezawa ^a

PMCID: PMC3089136 PMID: 21754541

Abstract

The asymmetric unit of the title compound, C₂₆H₂₀O₄, contains two independent conformers. The aromatic rings of the aroyl groups are twisted with respect to the naphthalene ring systems to form dihedral angles of 66.58 (6) and 66.45 (6)° in one conformer, and 75.00 (7) and 81.17 (6)° in the other conformer. The crystal packing is stabilized by weak intermolecular C—H⋯O hydrogen bonds and by C—H⋯π interactions.

Related literature

For information on the electrophilic aromatic substitution of naphthalene derivatives, see: Okamoto & Yonezawa (2009 ▶). For the structures of closely related compounds, see: Kataoka et al. (2010 ▶); Kato et al. (2010 ▶, 2011 ▶); Nakaema et al. (2008 ▶); Nishijima et al. (2010 ▶); Watanabe et al. (2010 ▶).

Experimental

Crystal data

C₂₆H₂₀O₄
M _r = 396.42
Triclinic,
a = 8.42828 (15) Å
b = 12.5953 (2) Å
c = 20.0578 (4) Å
α = 96.222 (1)°
β = 99.688 (1)°
γ = 102.727 (1)°
V = 2023.76 (6) Å³
Z = 4
Cu Kα radiation
μ = 0.71 mm⁻¹
T = 193 K
0.60 × 0.40 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: numerical (NUMABS; Higashi, 1999 ▶) T _min = 0.677, T _max = 0.933
32431 measured reflections
7263 independent reflections
5957 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.115
S = 1.08
7263 reflections
546 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku, 2010 ▶); program(s) used to solve structure: IL MILIONE (Burla et al., 2007 ▶); 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/S160053681101508X/rz2585sup1.cif

e-67-o1250-sup1.cif^{(33.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681101508X/rz2585Isup2.hkl

e-67-o1250-Isup2.hkl^{(348.2KB, hkl)}

Supplementary material file. DOI: 10.1107/S160053681101508X/rz2585Isup3.cml

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

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

Cg1 and Cg2 are the centroids of the C19–C24 and C4–C9 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C15—H15⋯O3ⁱ	0.95	2.57	3.5191 (19)	176
C25—H25C⋯O4ⁱⁱ	0.98	2.56	3.348 (2)	138
C51—H51C⋯O8ⁱⁱⁱ	0.98	2.47	3.371 (2)	152
C3—H3⋯Cg1^iv	0.95	2.59	3.416 (11)	145
C14—H14⋯Cg2^v	0.95	2.86	3.578 (9)	133

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

Acknowledgments

The authors thank Professor Keiichi Noguchi, Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, for technical advice. This work was partially supported by the Mukai Science and Technology Foundation.

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). Recently, we have reported the crystal structures of several 1,8-diaroylated naphthalene homologues exemplified by 1,8-bis(4-aminobenzoyl)-2,7-dimethoxynaphthalene (Nishijima et al., 2010) and 1,8-dibenzoyl-2,7-dimethoxynaphthalene (Nakaema et al., 2008). The aroyl groups at the 1,8-positions of the naphthalene rings in these compounds are connected in an almost perpendicular fashion. In this course, the crystal structures of 1-monoaroylated naphthalene compounds and the β-isomers of 3-monoaroylated compounds have been also clarified such as 1-benzoyl-2,7-dimethoxynaphthalene (Kato, et al., 2010), 1-(3-nitrobenzoyl)-2,7-dimethoxynaphthalene (Kataoka et al., 2010), 3-benzoyl-2,7-dimethoxynaphthalene (Kato et al., 2011), and (3,6-dimethoxy-2-naphthyl)(4-fluorophenyl)methanone (Watanabe et al., 2010). 1-Aroylated naphthalene compounds have been revealed to have essentially the same non-coplanar structure as the 1,8-diaroylated naphthalenes. 3-Substituted aroylnaphthalene compounds are generally regarded to be thermodynamically more stable than the corresponding 1-positioned isomeric molecules, with the aroyl groups connected to the naphthalene rings in a moderately twisted fashion. As a part of our continuous study on the molecular structures of this kind of homologous molecules, the crystal structure of title compound, a 1,6-dibenzoylated naphthalene derivative, is discussed in this paper.

There are two independent conformers in the asymmetric unit of the title compound. The conformers, labeled (I) and (II), are shown in Fig. 1. Each conformer has essentially the same non-coplanar structure, the main difference consisting in the dihedral angles formed by the benzene rings with the naphthalene ring systems. Conformer (II) shows a larger dihedral angle for the benzene ring of the aroyl group at 6-position than that of the benzene ring of the aroyl group at 1-potision [81.17 (6) and 75.00 (7)°], whereas very similar dihedral angles are observed for conformer (I) [66.45 (6) and 66.58 (6)°]. These angles could be compared with those reported for related 1- and 3-monoaroylated naphthalenes, e. g. (2,7-dimethoxynaphthalen-1-yl)(phenyl)methanone (75.34 (7), 86.47 (7) and 76.55 (6)°; Kato et al., 2010) and (3,6-dimethoxynaphthalen-2-yl)(phenyl)methanone (68.32 (5)°; Kato et al., 2011). The torsion angles between the carbonyl groups and the naphthalene ring of conformer (I) are 116.90 (14) (C1—C10—C11—O3) and 48.7 (2)° (C5—C6—C18—O4), those of conformer (II) are 106.70 (17) (C27—C36—C37—O7) and 73.7 (2)° (C31—C32—C44—O8). In the crystal structure, the molecular packing is stabilized mainly by weak two intermolecular C—H···O hydrogen bonds in conformer (I) (Table 1, Fig. 2). Moreover, a C—H···O hydrogen bond between the hydrogen atom of a 2-methoxy group and the oxygen atom of a carbonyl group is observed in conformer (II) (Table 1, Fig. 3). The crystal structure is further stabilized by C—H···π interactions (Table 1). In the crystal structure, conformer (I) and (II) are alternately piled up along a axis as shown in Fig. 4.

Experimental

To a 50 ml flask, benzoyl chloride (3.2 mmol, 350 mg), aluminium chloride (3.4 mmo1, 450 mg) and methylene chloride (2.5 ml) were added and stirred at 273 K. To the reaction mixture thus obtained, was then added 3-benzoyl-2,7-dimethoxynaphthalene (1.0 mmol, 294 mg). After the reaction mixture was stirred at 273 K for 72 h, it was poured into ice-cold water (10 ml). The aqueous layer was extracted with CHCl₃ (10 ml × 3). The combined extracts were washed with 2M aqueous NaOH followed by washing with brine. The organic layers thus obtained were dried over anhydrous MgSO₄. The solvent was removed under reduced pressure to give cake (quant.). The crude product was purified by recrystallization from ethanol (34% yield). Colourless platelet single crystals suitable for X-ray diffraction analysis were obtained by repeated crystallization from a hexane/chloroform (1:1 v/v) solution. ¹H NMR δ (400 MHz, CDCl₃, p.p.m.); 3.60(3H, s), 3.82(3H, s), 6.88(1H, s), 7.23(1H, d, J = 8.4 Hz), 7.41–7.48(4H, m), 7.54–7.62(2H, m), 7.82–7.87(4H, m), 7.89(1H, d, J = 1.6 Hz), 7.92(1H, d, J = 9.2 Hz). ¹³C NMR δ (75 MHz, CDCl₃, p.p.m.): 55.45, 56.31, 102.36, 110.99, 121.64, 123.35, 128.24, 128.63, 128.94, 129.51, 129.87, 130.26, 132.00, 133.04, 133.54, 134.06, 137.75, 137.94, 156.08, 156.39, 195.77, 197.72. IR (KBr); 1668(C═O), 1624, 1578, 1497(Ar, naphthalene) cm^-1. HRMS (m/z); [M + H]⁺ Calcd for C₂₆H₂₁O₄, 397.1440; found, 397.1444. M.p. = 429.4–431.8 K