(3,6-Dimeth­oxy­naphthalen-2-yl)(phen­yl)methanone

In the title compound, C₁₉H₁₆O₃, the dihedral angle between the naphthalene ring system and the phenyl ring is 68.32 (5)°. The bridging carbonyl C—C(=O)—C plane makes a dihedral angle of 54.32 (5)° with the naphthalene ring system and 21.45 (6)° with the phenyl ring. An inter­molecular C—H...O hydrogen bond exists between the H atom of one meth­oxy group and the O atom of the second meth­oxy group in an adjacent mol­ecule. The crystal packing is additionally stabilized by a weak C—H...O inter­molecular inter­action between an H atom of the naphthalene ring and the O atom of the carbonyl group.

Key indicators

• Single-crystal X-ray study
• T = 193 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.034
• wR factor = 0.098
• Data-to-parameter ratio = 13.5

checkCIF/PLATON results

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Alert level C
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          3

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

In the course of our study on selective electrophilic aromatic aroylation of 2,7-dimethoxynaphthalene, peri-aroylnaphthalene compounds have proved to be formed regioselectively with the aid of suitable acidic mediator (Okamoto & Yonezawa, 2009). Recently, we have reported the structures of 1,8-diaroyl-2,7-dimethoxynaphthalenes such as 1,8-bis(4-methylbenzoyl)-2,7-dimethoxynaphthalene (Muto et al., 2010) and 1,8-bis(4-aminobenzoyl)-2,7-dimethoxynaphthalene (Nishijima et al., 2010). The aroyl groups at the 1,8-positions of the naphthalene rings in these compounds are bonded in a nearly perpendicular manner but the benzene rings of the aroyl groups tilt slightly toward the exo sides of the naphthalene rings. Such 1-aroylnaphthalene homologues as (2,7-dimethoxynaphthalen-1-yl)(3-nitrophenyl)methanone (Kataoka et al., 2010) are also revealed to have essentially the same non-coplanar structure as observed for 1,8-diaroylated naphthalenes. Furthermore, we reported the crystal structure analysis of the corresponding β-isomers of 3-aroyl-2,7-dimethoxynaphthalenes such as 2-(4-chlorobenzoyl)-3,6-dimethoxynaphthalene (Nakaema, Okamoto et al., 2008) and (4-fluorophenyl) (3,6-dimethoxy-2-naphthyl)methanone (Watanabe et al., 2010). In the 3-aroylated naphthalenes, which are generally regarded to be thermodynamically more stable than the corresponding 1-positioned isomeric molecules, the aroyl groups are connected to the naphthalene rings in a moderately twisted fashion. On the other hand, there are several unique structural features in the benzoylated naphthalene homologues, 1-benzoyl-2,7-dimethoxynaphthalene (Kato et al., 2010) and 1,8-dibenzoyl-2,7-dimethoxynaphthalene (Nakaema, Watanabe et al., 2008). 1-Benzoyl-2,7-dimethoxynaphthalene contains three independent conformers and each of them forms a columnar structure, respectively. As a part of our ongoing study on the synthesis and structure of these homologous molecules, the crystal structure analysis of the title compound, a 3-monoaroylnaphthalene, is discussed in this article.

The molecular structure of the title molecule is displayed in Fig. 1. The benzene group is bonded to the naphthalene ring with a non-coplanar configuration. The dihedral angle between the best planes of the benzene ring (C12—C17) and the naphthalene ring (C1—C10) is 68.32 (5)°. The bridging carbonyl plane (O1—C3—C11—C12) makes a relatively large dihedral angle of 54.32 (5)° with the naphthalene ring (C1—C10) [C2—C3—C11—O1 torsion angle = -125.86 (12)°], whereas it makes a rather small dihedral angle of 21.45 (6)° with benzene ring (C12—C17) [O1—C11—C12—C13 torsion angle = -156.47 (11)°].

The crystal packing exhibits a weak C—H···O intermolecular interaction between the oxygen atom of the carbonyl group and the hydrogen atom of the naphthalene ring (Table 1, Fig. 2). The packing is additionally stabilized by a C—H···O hydrogen bond between the hydrogen of the 2-methoxy group, which is situated adjacent to the benzoyl group, and the ethereal oxygen atom of the 7-methoxy group in the neighboring molecule (Table 1, Fig. 3).

Related literature

For electrophilic aromatic substitution of naphthalene derivatives affording peri-aroylated compounds regioselectively, see: Okamoto & Yonezawa (2009). For the structures of closely related compounds, see: Kataoka et al. (2010); Kato et al. (2010); Muto et al. (2010); Nakaema, Okamoto et al. (2008); Nakaema, Watanabe et al. (2008); Nishijima et al. (2010); Watanabe et al. (2010).

S2. Experimental

A mixture of 2,7-dimethoxynaphthalene (3.74 g, 19.9 mmol), FeCl₃ (4.95 g, 37.1 mmol), trichloromethylbenzene (2.9 ml, 20 mmol) and dichloromethane (50 ml) was stirred at 293 K for 6 h, and the reaction mixture was poured into ice-cooled water followed by extraction with CHCl₃ (30 ml × 3). The combined extracts were washed with 2 M aqueous NaOH followed by washing with brine. The organic layer thus obtained was dried over anhydrous MgSO₄. The solvent was removed under reduced pressure to give cakes (yield 72%). The crude product was purified by flush silica gel chromatography (CHCl₃). Colorless platelet single crystals suitable for X-ray diffraction were obtained by crystallization from hexane and chloroform (yield 21%).

Spectroscopic Data:

¹H NMR δ (400 MHz, CDCl₃); 3.83 (3H, s), 3.95 (3H, s), 7.05 (1H, dd, J = 2.4, 9.2 Hz), 7.11 (1H, d, J = 2.4 Hz), 7.14 (1H, s), 7.44 (2H, t, J = 8.0 Hz), 7.56 (1H, t, J = 7.6 Hz), 7.69 (1H, d, J = 9.2 Hz), 7.78 (1H, s), 7.83–7.85 (2H, m) p.p.m..

¹³C NMR δ (75 MHz, CDCl₃); 55.34, 55.54, 105.00, 105.38, 117.02, 123.15, 127.89, 128.18, 129.93, 130.01, 130.07, 132.87, 137.11, 138.06, 155.83, 159.30, 196.02 p.p.m..

IR (KBr): 1627 (C═O), 1580, 1502 (Ar, naphthalene), 1213 cm^-1.

HRMS (m/z): [M + H]⁺ Calcd for C₁₉H₁₇O₃, 293.1178; found, 293.1203.

m.p. = 438.7–441.5 K.

S3. Refinement

H atom positions were derived from geometrical considerations and were subsequently refined as riding atoms, with C—H = 0.95 (aromatic) and 0.98 (methyl) Å, and with U_iso(H) = 1.2U_eq(C) or 1.5(methyl).

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); 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 (Sheldrick, 2008).

Figures

	Fig. 1. Molecular structure with displacement ellipsoids at 50% probability level for non-H atoms.
	Fig. 2. The C4—H4···O1 intermolecular interaction [symmetry code: (i) – x + 2, – y, – z + 1].
	Fig. 3. The C18—H18B···O3 intermolecular interaction [symmetry code: (ii) x – 1, y, z – 1].

(3,6-Dimethoxynaphthalen-2-yl)(phenyl)methanone

Crystal data

C19H16O3	F(000) = 616
Mr = 292.32	Dx = 1.301 Mg m^−3
Monoclinic, P21/c	Melting point = 438.7–441.5 K
Hall symbol: -P 2ybc	Cu Kα radiation, λ = 1.54187 Å
a = 8.7186 (2) Å	Cell parameters from 16018 reflections
b = 20.4650 (4) Å	θ = 4.3–68.2°
c = 8.5675 (2) Å	µ = 0.71 mm^−1
β = 102.475 (1)°	T = 193 K
V = 1492.57 (6) Å^3	Platelet, colorless
Z = 4	0.60 × 0.50 × 0.20 mm

Data collection

Rigaku R-AXIS RAPID diffractometer	2735 independent reflections
Radiation source: rotating anode	2509 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.044
Detector resolution: 10.000 pixels mm^-1	θmax = 68.2°, θmin = 4.3°
ω scans	h = −10→10
Absorption correction: numerical (NUMABS; Higashi, 1999)	k = −24→24
Tmin = 0.677, Tmax = 0.872	l = −10→10
26682 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.034	H-atom parameters constrained
wR(F^2) = 0.098	w = 1/[σ^2(Fo^2) + (0.0584P)^2 + 0.2227P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
2735 reflections	Δρmax = 0.23 e Å^−3
202 parameters	Δρmin = −0.17 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0131 (8)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² 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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.78878 (10)	0.03272 (4)	0.31564 (10)	0.0421 (2)
O2	0.82137 (9)	0.20198 (4)	0.16422 (9)	0.0365 (2)
O3	1.49637 (9)	0.28351 (4)	0.80270 (10)	0.0420 (2)
C1	1.04784 (12)	0.23386 (5)	0.36717 (13)	0.0299 (2)
H1	1.0346	0.2786	0.3379	0.036*
C2	0.94725 (12)	0.18810 (5)	0.28459 (13)	0.0297 (2)
C3	0.96544 (12)	0.12068 (5)	0.32677 (12)	0.0301 (2)
C4	1.08301 (13)	0.10241 (5)	0.45329 (12)	0.0314 (3)
H4	1.0931	0.0577	0.4834	0.038*
C5	1.18928 (12)	0.14824 (5)	0.53981 (12)	0.0307 (3)
C6	1.31320 (13)	0.13009 (5)	0.66941 (13)	0.0361 (3)
H6	1.3272	0.0854	0.6992	0.043*
C7	1.41212 (13)	0.17582 (6)	0.75144 (14)	0.0378 (3)
H7	1.4948	0.1629	0.8374	0.045*
C8	1.39183 (12)	0.24263 (6)	0.70863 (13)	0.0335 (3)
C9	1.27567 (12)	0.26199 (5)	0.58315 (13)	0.0314 (3)
H9	1.2648	0.3069	0.5544	0.038*
C10	1.17134 (12)	0.21514 (5)	0.49575 (12)	0.0288 (2)
C11	0.85594 (12)	0.06982 (5)	0.24066 (13)	0.0312 (2)
C12	0.83398 (13)	0.06328 (5)	0.06375 (13)	0.0320 (3)
C13	0.94512 (15)	0.08664 (5)	−0.01647 (14)	0.0386 (3)
H13	1.0356	0.1089	0.0408	0.046*
C14	0.92417 (18)	0.07753 (6)	−0.18018 (15)	0.0495 (3)
H14	1.0017	0.0925	−0.2343	0.059*
C15	0.7911 (2)	0.04677 (6)	−0.26460 (16)	0.0550 (4)
H15	0.7757	0.0418	−0.3772	0.066*
C16	0.67992 (18)	0.02314 (7)	−0.18521 (16)	0.0546 (4)
H16	0.5884	0.0018	−0.2432	0.066*
C17	0.70235 (15)	0.03068 (6)	−0.02102 (15)	0.0436 (3)
H17	0.6274	0.0135	0.0337	0.052*
C18	0.78092 (13)	0.26937 (5)	0.13734 (15)	0.0371 (3)
H18A	0.7644	0.2890	0.2367	0.044*
H18B	0.6843	0.2730	0.0545	0.044*
H18C	0.8663	0.2923	0.1024	0.044*
C19	1.47866 (16)	0.35166 (6)	0.77225 (16)	0.0468 (3)
H19A	1.4949	0.3611	0.6648	0.056*
H19B	1.5563	0.3757	0.8514	0.056*
H19C	1.3727	0.3652	0.7795	0.056*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0504 (5)	0.0376 (4)	0.0393 (5)	−0.0111 (4)	0.0122 (4)	0.0032 (3)
O2	0.0385 (4)	0.0293 (4)	0.0366 (4)	0.0020 (3)	−0.0034 (3)	−0.0004 (3)
O3	0.0390 (5)	0.0418 (5)	0.0411 (5)	−0.0081 (3)	−0.0008 (4)	−0.0024 (4)
C1	0.0344 (5)	0.0250 (5)	0.0309 (6)	0.0011 (4)	0.0086 (4)	0.0016 (4)
C2	0.0317 (5)	0.0303 (5)	0.0273 (5)	0.0022 (4)	0.0067 (4)	0.0012 (4)
C3	0.0344 (5)	0.0282 (5)	0.0291 (5)	−0.0002 (4)	0.0095 (4)	−0.0009 (4)
C4	0.0376 (6)	0.0267 (5)	0.0308 (6)	0.0017 (4)	0.0096 (5)	0.0024 (4)
C5	0.0327 (5)	0.0311 (5)	0.0293 (5)	0.0015 (4)	0.0091 (4)	0.0016 (4)
C6	0.0387 (6)	0.0333 (6)	0.0353 (6)	0.0025 (4)	0.0053 (5)	0.0056 (4)
C7	0.0348 (6)	0.0421 (6)	0.0341 (6)	0.0019 (5)	0.0022 (5)	0.0048 (5)
C8	0.0305 (5)	0.0392 (6)	0.0314 (6)	−0.0038 (4)	0.0079 (4)	−0.0028 (4)
C9	0.0329 (5)	0.0298 (5)	0.0324 (6)	−0.0009 (4)	0.0093 (4)	0.0000 (4)
C10	0.0298 (5)	0.0305 (5)	0.0278 (5)	0.0005 (4)	0.0099 (4)	0.0000 (4)
C11	0.0330 (5)	0.0262 (5)	0.0345 (6)	0.0018 (4)	0.0076 (4)	0.0019 (4)
C12	0.0375 (6)	0.0243 (5)	0.0330 (6)	0.0023 (4)	0.0053 (4)	−0.0010 (4)
C13	0.0491 (7)	0.0298 (5)	0.0386 (6)	−0.0008 (5)	0.0135 (5)	−0.0006 (5)
C14	0.0766 (9)	0.0365 (6)	0.0407 (7)	0.0071 (6)	0.0247 (7)	0.0016 (5)
C15	0.0892 (11)	0.0407 (7)	0.0322 (7)	0.0188 (7)	0.0062 (7)	−0.0044 (5)
C16	0.0614 (8)	0.0492 (8)	0.0447 (8)	0.0046 (6)	−0.0076 (6)	−0.0125 (6)
C17	0.0428 (6)	0.0416 (6)	0.0438 (7)	−0.0027 (5)	0.0034 (5)	−0.0060 (5)
C18	0.0373 (6)	0.0318 (6)	0.0390 (6)	0.0040 (4)	0.0014 (5)	0.0045 (4)
C19	0.0488 (7)	0.0413 (7)	0.0480 (7)	−0.0118 (5)	0.0053 (6)	−0.0059 (5)

Geometric parameters (Å, º)

O1—C11	1.2224 (13)	C9—C10	1.4188 (15)
O2—C2	1.3637 (13)	C9—H9	0.9500
O2—C18	1.4299 (13)	C11—C12	1.4921 (15)
O3—C8	1.3649 (13)	C12—C13	1.3884 (16)
O3—C19	1.4211 (15)	C12—C17	1.3891 (16)
C1—C2	1.3706 (15)	C13—C14	1.3873 (17)
C1—C10	1.4168 (15)	C13—H13	0.9500
C1—H1	0.9500	C14—C15	1.379 (2)
C2—C3	1.4265 (14)	C14—H14	0.9500
C3—C4	1.3731 (15)	C15—C16	1.386 (2)
C3—C11	1.4948 (15)	C15—H15	0.9500
C4—C5	1.4110 (15)	C16—C17	1.3864 (18)
C4—H4	0.9500	C16—H16	0.9500
C5—C10	1.4198 (14)	C17—H17	0.9500
C5—C6	1.4212 (15)	C18—H18A	0.9800
C6—C7	1.3607 (17)	C18—H18B	0.9800
C6—H6	0.9500	C18—H18C	0.9800
C7—C8	1.4166 (16)	C19—H19A	0.9800
C7—H7	0.9500	C19—H19B	0.9800
C8—C9	1.3668 (16)	C19—H19C	0.9800
C2—O2—C18	116.93 (8)	O1—C11—C3	120.03 (10)
C8—O3—C19	117.45 (9)	C12—C11—C3	119.46 (9)
C2—C1—C10	120.71 (9)	C13—C12—C17	119.52 (11)
C2—C1—H1	119.6	C13—C12—C11	121.46 (10)
C10—C1—H1	119.6	C17—C12—C11	118.97 (10)
O2—C2—C1	124.67 (9)	C14—C13—C12	120.04 (12)
O2—C2—C3	114.85 (9)	C14—C13—H13	120.0
C1—C2—C3	120.42 (10)	C12—C13—H13	120.0
C4—C3—C2	119.11 (10)	C15—C14—C13	120.24 (13)
C4—C3—C11	119.23 (9)	C15—C14—H14	119.9
C2—C3—C11	121.62 (9)	C13—C14—H14	119.9
C3—C4—C5	121.82 (10)	C14—C15—C16	120.00 (12)
C3—C4—H4	119.1	C14—C15—H15	120.0
C5—C4—H4	119.1	C16—C15—H15	120.0
C4—C5—C10	118.63 (10)	C15—C16—C17	119.92 (13)
C4—C5—C6	122.61 (10)	C15—C16—H16	120.0
C10—C5—C6	118.76 (10)	C17—C16—H16	120.0
C7—C6—C5	120.92 (10)	C16—C17—C12	120.23 (12)
C7—C6—H6	119.5	C16—C17—H17	119.9
C5—C6—H6	119.5	C12—C17—H17	119.9
C6—C7—C8	120.02 (10)	O2—C18—H18A	109.5
C6—C7—H7	120.0	O2—C18—H18B	109.5
C8—C7—H7	120.0	H18A—C18—H18B	109.5
O3—C8—C9	125.00 (10)	O2—C18—H18C	109.5
O3—C8—C7	114.12 (10)	H18A—C18—H18C	109.5
C9—C8—C7	120.88 (10)	H18B—C18—H18C	109.5
C8—C9—C10	120.06 (10)	O3—C19—H19A	109.5
C8—C9—H9	120.0	O3—C19—H19B	109.5
C10—C9—H9	120.0	H19A—C19—H19B	109.5
C1—C10—C9	121.37 (10)	O3—C19—H19C	109.5
C1—C10—C5	119.28 (10)	H19A—C19—H19C	109.5
C9—C10—C5	119.34 (10)	H19B—C19—H19C	109.5
O1—C11—C12	120.47 (10)
C18—O2—C2—C1	−8.42 (15)	C8—C9—C10—C1	178.71 (10)
C18—O2—C2—C3	168.77 (9)	C8—C9—C10—C5	−0.15 (15)
C10—C1—C2—O2	176.97 (9)	C4—C5—C10—C1	0.12 (15)
C10—C1—C2—C3	−0.07 (16)	C6—C5—C10—C1	−179.74 (9)
O2—C2—C3—C4	−175.98 (9)	C4—C5—C10—C9	179.01 (9)
C1—C2—C3—C4	1.34 (16)	C6—C5—C10—C9	−0.85 (15)
O2—C2—C3—C11	1.64 (14)	C4—C3—C11—O1	51.76 (14)
C1—C2—C3—C11	178.96 (9)	C2—C3—C11—O1	−125.86 (11)
C2—C3—C4—C5	−1.91 (16)	C4—C3—C11—C12	−126.07 (10)
C11—C3—C4—C5	−179.58 (9)	C2—C3—C11—C12	56.32 (14)
C3—C4—C5—C10	1.18 (16)	O1—C11—C12—C13	−156.48 (11)
C3—C4—C5—C6	−178.96 (10)	C3—C11—C12—C13	21.34 (15)
C4—C5—C6—C7	−179.10 (10)	O1—C11—C12—C17	20.86 (15)
C10—C5—C6—C7	0.75 (16)	C3—C11—C12—C17	−161.33 (10)
C5—C6—C7—C8	0.35 (17)	C17—C12—C13—C14	0.16 (17)
C19—O3—C8—C9	2.94 (16)	C11—C12—C13—C14	177.48 (10)
C19—O3—C8—C7	−176.95 (10)	C12—C13—C14—C15	1.68 (18)
C6—C7—C8—O3	178.50 (10)	C13—C14—C15—C16	−1.88 (19)
C6—C7—C8—C9	−1.40 (17)	C14—C15—C16—C17	0.2 (2)
O3—C8—C9—C10	−178.60 (9)	C15—C16—C17—C12	1.61 (19)
C7—C8—C9—C10	1.28 (16)	C13—C12—C17—C16	−1.80 (17)
C2—C1—C10—C9	−179.52 (9)	C11—C12—C17—C16	−179.19 (11)
C2—C1—C10—C5	−0.65 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O1^i	0.95	2.58	3.4439 (13)	151
C18—H18B···O3^ii	0.98	2.42	3.3742 (15)	164

Symmetry codes: (i) −x+2, −y, −z+1; (ii) x−1, y, z−1.