{2,7-Dimeth­oxy-8-[4-(2-methyl­prop­yl)benzo­yl]naphthalen-1-yl}[4-(2-methyl­prop­yl)phen­yl]methanone

Kosuke Sasagawa; Daichi Hijikata; Rei Sakamoto; Akiko Okamoto; Noriyuki Yonezawa

doi:10.1107/S1600536812045953

. 2012 Nov 14;68(Pt 12):o3348. doi: 10.1107/S1600536812045953

{2,7-Dimethoxy-8-[4-(2-methylpropyl)benzoyl]naphthalen-1-yl}[4-(2-methylpropyl)phenyl]methanone

Kosuke Sasagawa ^a, Daichi Hijikata ^a, Rei Sakamoto ^a, Akiko Okamoto ^a,^*, Noriyuki Yonezawa ^a

PMCID: PMC3588949 PMID: 23476185

Abstract

In the molecule of the title compound, C₃₄H₃₆O₄, the two 4-isobutylbenzoyl groups at the 1- and 8-positions of the naphthalene ring system are aligned almost antiparallel, and the benzene rings make a dihedral angle of 21.59 (7)°. The dihedral angles between the benzene rings and the naphthalene ring system are 69.26 (6) and 64.29 (5)°. There are no classical hydrogen bonds in the structure, but inversion-related molecules engage in π–π stacking, with an interplanar spacing between related naphthalene groups of 3.4120 (16) Å.

Related literature

For details of the formation reaction of aroylated naphthalene compounds via electrophilic aromatic substitution of naphthalene derivatives, see: Okamoto & Yonezawa (2009 ▶); Okamoto et al. (2011 ▶). For the structures of closely related compounds, see: Hijikata et al. (2010 ▶); Muto et al. (2010 ▶); Sasagawa, Hijikata et al. (2011 ▶); Sasagawa, Muto et al. (2011 ▶); Sasagawa et al. (2012 ▶). graphic file with name e-68-o3348-scheme1.jpg

Experimental

Crystal data

C₃₄H₃₆O₄
M _r = 508.63
Monoclinic,
a = 18.5280 (4) Å
b = 7.83885 (15) Å
c = 20.2304 (4) Å
β = 103.642 (1)°
V = 2855.33 (10) Å³
Z = 4
Cu Kα radiation
μ = 0.60 mm⁻¹
T = 193 K
0.60 × 0.40 × 0.05 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: numerical (NUMABS; Higashi, 1999 ▶) T _min = 0.714, T _max = 0.971
50913 measured reflections
5237 independent reflections
3838 reflections with I > 2σ(I)
R _int = 0.052

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.126
S = 1.12
5237 reflections
350 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▶); cell refinement: PROCESS-AUTO; data reduction: PROCESS-AUTO; 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

Click here for additional data file.^{(26.7KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812045953/pk2455sup1.cif

e-68-o3348-sup1.cif^{(26.7KB, cif)}

Click here for additional data file.^{(251.3KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812045953/pk2455Isup2.hkl

e-68-o3348-Isup2.hkl^{(251.3KB, hkl)}

Click here for additional data file.^{(10.7KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812045953/pk2455Isup3.cml

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

Acknowledgments

The authors express their gratitude to Professor Keiichi Noguchi, Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, for technical advice. This work was partially supported by a Sasagawa Scientific Research Grant from the Japan Science Society.

supplementary crystallographic information

Comment

In the course of our study on selective electrophilic aromatic aroylation of the naphthalene ring core, 1,8-diaroylnaphthalene compounds have proved to be formed regioselectively by the aid of a suitable acidic mediator (Okamoto & Yonezawa, 2009, Okamoto et al., 2011). Recently, we have reported the X-ray crystal structures of 1,8-diaroylated 2,7-dimethoxynaphthalene derivatives such as [2,7-dimethoxy-8-(4-methylbenzoyl)-1-naphthyl](4-methylphenyl)methanone [1,8-bis(4-methylbenzoyl)-2,7-dimethoxynaphthalene] (Muto et al., 2010), {8-[4-(bromomethyl)benzoyl]-2,7-dimethoxynaphthalen-1-yl}[4-(bromomethyl)phenyl]methanone [1,8-bis(4-bromomethylbenzoyl)-2,7-dimethoxynaphthalene] (Sasagawa, Hijikata et al., 2011), {8-[4-(butoxy)benzoyl]-2,7-dimethoxynaphthalen-1-yl}[4-(butoxy)phenyl]methanone [1,8-bis(4-butoxylbenzoyl)-2,7-dimethoxynaphthalene] (Sasagawa, Muto et al., 2011), [2,7-dimethoxy-8-(4-propylbenzoyl)-naphthalen-1-yl](4-propylphenyl)-methanone [1,8-bis(4-butoxylbenzoyl)-2,7-dimethoxynaphthalene] (Sasagawa et al., 2012). The aroyl groups in these compounds are almost perpendicular to the naphthalene rings, and are oriented in opposite directions (anti-orientation). Moreover, we have also clarified that the aroyl groups of 2,7-dimethoxy-1,8-bis(4-phenoxybenzoyl)naphthalene (Hijikata et al., 2010) are oriented in the same direction (syn-orientation). As part of our ongoing studies on the molecular structures of these kinds of homologous molecules, the X-ray crystal structure of the title compound, 1,8-diaroylatednaphthalene bearing isobutyl groups, is discussed in this article.

The molecular structure of the title compound is displayed in Fig 1. Two 4-isobutylbenzoyl groups are situated in the anti-orientation. The dihedral angle between the best planes of the two phenyl rings is 21.59 (7)°. The dihedral angles between the best planes of the 4-isobutylphenyl rings and the naphthalene ring are 69.26 (6)° and 64.29 (5)°.

The C═O bond of the ketonic carbonyl moiety (C12═O4), carbon atom (C31) of isobutyl groups, and benzene ring lie on the same plane [torsion angles O4—C12—C19—C24 = 2.49 (18)°; C31—C22—C23—C24 = 176.11 (14)°]. The corresponding torsion angles in the other aroyl group are 172.86 (12)° [O3—C11—C13—C14] and 178.36 (17)° [C27—C16—C17—C18], respectively.

In the molecular packing, C—H···O interactions between the carbonyl oxygen atoms and hydrogen atoms of benzene ring are observed along b axis. The C—H···O interactions effectively contribute to stabilization of the molecular alignment (C21—H21···O4 = 2.34 Å; symmetry code: x,-1 + y, z; Fig. 2).

Experimental

To a 50 ml flask, 4-isobutylbenzoic acid (1.96 g, 11.0 mmol), phosphorus pentoxide–methanesulfonic acid mixture (P₂O₅–MsOH [1/10 w/w]; 22.0 ml) were placed and stirred at 333 K. To the solution thus obtained, 2,7-dimethoxynaphthalene (941 mg, 5.0 mmol) was added. After the reaction mixture was stirred at 333 K for 1.0 h, the reaction mixture was poured into ice-cold water (30 ml). The aqueous layer was extracted with CHCl₃ (15 ml × 3). The combined extracts were washed with 2 M 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 (100% yield). The crude product was purified by recrystallization from methanol (32% yield). Colorless platelet single crystals suitable for X-ray diffraction were obtained by repeated crystallization from ethanol.

Spectroscopic Data:

¹H-NMR δ (300 MHz, CDCl₃): 0.91 (12H, d, J = 6.6 Hz), 1.89 (2H, m, J= 6.6 Hz), 2.49 (4H, d, J = 6.6 Hz), 3.68 (6H, s), 7.09 (4H, d, J = 7.5 Hz), 7.20 (2H, d, J = 9.0 Hz), 7.59(2H, d, J = 7.5 Hz), 7.95 (4H, d, J = 9.0 Hz)

¹³C-NMR δ (75 MHz, CDCl₃): 22.3, 29.3, 45.4, 56.2, 111.1, 121.5, 125.3, 128.5, 128.9, 129.4, 131.7, 136.4, 146.7, 156.0, 196.2 p.p.m.

IR (KBr): 2952 (CH₃), 2911 (CH₂), 1652 (C=O), 1605, 1510, 1460 (Ar) cm^-1

HRMS (m/z): [M+H]⁺ calcd. for C₃₄H₃₇O₄, 509.2692, found, 509.2608

m.p.= 472.0—474.0 K