7,9-Dimethyl-3-phenyl­naphtho[1,2-b]furan-4,5-dione

In the title compound, C₂₀H₁₄O₃, π–π stacking inter­actions [3.474 (2)–3.789 (2) Å] dominate the crystal structure. The dihedral angle between the phenyl ring and fused-ring system is 32.3 (3)°.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.040
• wR factor = 0.119
• Data-to-parameter ratio = 15.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT333_ALERT_2_C Large Average Benzene C-C Dist.  C9     -C18           1.45 Ang.
PLAT335_ALERT_2_C Large Benzene C-C Range .......  C9     -C18           0.18 Ang.
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C10    -   C11    ...       1.55 Ang.

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 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
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Polycyclic ortho-quinonoid structures constitute a large category of significant compounds which possess a broad spectrum of biological activities such as antioxidant activity (Ng et al., 2000), cytotoxicity (Park et al., 1999), antifungal activity (Chang et al., 1991), antineoplastic activity (Kongkathip et al., 2003). Recently, we are engaged in a program directed at searching for new bioactive ortho-quinoid compounds. As part of our investigation (Shen et al., 2005), we reported the synthesis and single-crystal structure of 7, 9-dimethyl-3-phenylnaphtho [1, 2 - b] furan-4, 5-dione (I).

The X-ray study of (I) confirms the previously proposed molecular structure based on spectroscopic data (Figure. 1).

The C—C, C=C, C—O and C=O distances show no remarkable features, except that the bond C10—C11(1.548 (2) Å) is significantly longer than normal distance of C—C bond.

A structural feature of (I) is the presence of intermolecular strong π-π stacking interactions between adjacent molecules. The geometric parameters are within the acceptable range (Janiak, 2000). The Cg1···Cg2ⁱ, Cg1···Cg3ⁱⁱ and Cg2···Cg3ⁱⁱ distances are 3.474 (2), 3.789 (2) and 3.690 (2) Å respectively [symmetry code: (i) -x, 1 - y, 2 - z, (ii)-x, -y, 2 - z, Cg1, Cg2 and Cg3 are centroids of the C10-containing ring, C13-containing ring and the O1-containing ring] (Figure. 2).

The naphtho[1,2-b]furan-4,5-dione part of the title molecule is approximately coplanar, the interplanar distances between neighbouring 13-membered ring planes are 3.458 (2) and 3.527 (2) Å.

Obviously, aromatic π-π stacking interactions play a key role in assembling the supramolecular structure.

Related literature

For related literature, see: Chang et al. (1991); Janiak (2000); Ng et al. (2000); Kongkathip et al. (2003); Park et al. (1999); Shen et al. (2005). Cg1, Cg2 and Cg3 are centroids

of the C10-containing ring, the C13-containing ring

and the O1-containing ring.

For related literature, see: Kongkathip et al. (2003).

S2. Experimental

The title compound was prepared from 3-phenylbenzofuran-4,5-dione and N-(2-methylpenta-1,3-dienyl)acetamide by the strategy of Diels-Alder. N-(2-methylpenta-1,3-dienyl)acetamide (0.139 g, 1 mmol) and 3-phenylbenzofuran-4,5-dione (0.240 g, 1 mmol) were added to benzene (30 ml), and refluxed for 5 h. Then, silica gel (10 g, 80–120 mesh) was added to the solution and the solvent was removed in vacuum at 45°C.

The resulted dry reaction-mixture-coated silica gel was then stirred at 45°C for 24 h. Purification by chromatography on silica gel (CHCl₃/CH₃OH) gave target compound (I) in 65% yield.

Crystals of (I) suitable for X-ray analysis were grown from CDCl₃ solution.

¹H-NMR (300 MHz, CDCl₃, TMS): δ 2.35(s, 3H), 2.67(s, 3H), 7.23(s, 1H), 7.35–7.42(m, 3H), 7.59(s, 1H), 7.64 (d, 1H), 7.75(s, 1H).

¹³C NMR (75 MHz, CDCl₃): δ 21.16, 21.68, 118.71, 124.14, 127.19, 128.29, 128.30, 128.33, 128.34, 128.35, 129.09, 129.46, 129.63, 135.47, 139.33, 140.19, 140.81, 163.30, 174.84, 181.10.

ESI-MS(m/z): 303 ([M+H]⁺).

S3. Refinement

All H atoms were positioned geometrically and refined with a riding model, with distances 0.96 (CH₃) and 0.93 Å (CH) with U_iso(H) = 1.2 (1.5 for methyl groups) times U_eq(C).

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL (Bruker, 1999).

Figures

	Fig. 1. The molecular structure of (I), with atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. Part of the crystal structure of (I) formed by π-π stacking interactions. Labels Cg represent the centroids of rings. H atoms have been omitted for clarity. Symmetry code:(i) -x, 1 - y, 2 - z, (ii) -x, -y, 2 - z.

7,9-Dimethyl-3-phenylnaphtho[1,2-b]furan-4,5-dione

Crystal data

C20H14O3	F(000) = 632
Mr = 302.31	Dx = 1.373 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1012 reflections
a = 7.792 (2) Å	θ = 2.8–26.9°
b = 7.602 (2) Å	µ = 0.09 mm^−1
c = 24.746 (7) Å	T = 293 K
β = 93.610 (5)°	Block, red
V = 1463.0 (7) Å^3	0.50 × 0.38 × 0.27 mm
Z = 4

Data collection

Bruker SMART 1K CCD area-detector diffractometer	3174 independent reflections
Radiation source: fine-focus sealed tube	2534 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
φ and ω scans	θmax = 27.1°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.956, Tmax = 0.976	k = −9→9
9844 measured reflections	l = −31→30

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.119	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0585P)^2 + 0.3061P] where P = (Fo^2 + 2Fc^2)/3
3174 reflections	(Δ/σ)max = 0.001
210 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.20 e Å^−3

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
C1	0.33460 (19)	0.0790 (2)	0.94412 (6)	0.0528 (4)
H1	0.4424	0.0311	0.9392	0.063*
C2	0.21428 (17)	0.10566 (18)	0.90371 (5)	0.0454 (3)
C3	0.24088 (19)	0.06386 (18)	0.84666 (5)	0.0482 (3)
C4	0.4054 (2)	0.0779 (2)	0.82849 (6)	0.0577 (4)
H4	0.4939	0.1223	0.8515	0.069*
C5	0.4389 (2)	0.0267 (3)	0.77658 (7)	0.0717 (5)
H5	0.5498	0.0361	0.7650	0.086*
C6	0.3096 (3)	−0.0379 (3)	0.74210 (7)	0.0749 (5)
H6	0.3328	−0.0736	0.7074	0.090*
C7	0.1453 (3)	−0.0498 (2)	0.75908 (7)	0.0695 (5)
H7	0.0574	−0.0931	0.7356	0.083*
C8	0.1096 (2)	0.0023 (2)	0.81090 (6)	0.0579 (4)
H8	−0.0023	−0.0040	0.8218	0.069*
C9	0.06983 (16)	0.17866 (17)	0.93019 (5)	0.0422 (3)
C10	−0.09938 (18)	0.23874 (19)	0.91119 (6)	0.0486 (3)
C11	−0.21411 (17)	0.30834 (18)	0.95534 (6)	0.0493 (3)
C12	−0.14654 (17)	0.31760 (17)	1.01237 (5)	0.0440 (3)
C13	−0.25251 (18)	0.38256 (18)	1.05073 (6)	0.0500 (3)
H13	−0.3638	0.4180	1.0401	0.060*
C14	−0.19467 (19)	0.39517 (18)	1.10448 (6)	0.0505 (3)
C15	−0.02604 (19)	0.34631 (18)	1.11827 (6)	0.0496 (3)
H15	0.0150	0.3590	1.1542	0.059*
C16	0.08540 (17)	0.27926 (17)	1.08151 (5)	0.0450 (3)
C17	0.02245 (16)	0.26205 (16)	1.02753 (5)	0.0405 (3)
C18	0.11923 (16)	0.19215 (17)	0.98400 (5)	0.0412 (3)
C19	−0.3093 (2)	0.4566 (2)	1.14715 (7)	0.0664 (4)
H19A	−0.4067	0.5171	1.1303	0.100*
H19B	−0.2465	0.5349	1.1715	0.100*
H19C	−0.3480	0.3570	1.1669	0.100*
C20	0.2641 (2)	0.2282 (2)	1.10205 (6)	0.0600 (4)
H20A	0.2802	0.2562	1.1399	0.090*
H20B	0.3465	0.2916	1.0824	0.090*
H20C	0.2799	0.1041	1.0971	0.090*
O1	0.28067 (12)	0.13026 (14)	0.99344 (4)	0.0518 (3)
O2	−0.15827 (15)	0.23743 (19)	0.86475 (4)	0.0759 (4)
O3	−0.35925 (14)	0.35313 (18)	0.94093 (5)	0.0736 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0484 (7)	0.0687 (9)	0.0413 (7)	0.0050 (7)	0.0042 (6)	−0.0011 (7)
C2	0.0484 (7)	0.0455 (7)	0.0423 (7)	−0.0051 (6)	0.0027 (5)	0.0041 (6)
C3	0.0602 (8)	0.0444 (7)	0.0398 (7)	−0.0017 (6)	0.0017 (6)	0.0050 (6)
C4	0.0627 (9)	0.0629 (9)	0.0479 (8)	−0.0017 (7)	0.0065 (7)	−0.0002 (7)
C5	0.0794 (12)	0.0828 (12)	0.0548 (10)	0.0027 (9)	0.0181 (8)	0.0006 (9)
C6	0.1036 (14)	0.0796 (12)	0.0421 (9)	0.0043 (10)	0.0096 (9)	−0.0019 (8)
C7	0.0918 (13)	0.0705 (11)	0.0444 (8)	−0.0075 (9)	−0.0095 (8)	0.0001 (8)
C8	0.0670 (9)	0.0598 (9)	0.0460 (8)	−0.0077 (7)	−0.0029 (7)	0.0057 (7)
C9	0.0450 (7)	0.0410 (7)	0.0401 (7)	−0.0064 (5)	−0.0009 (5)	0.0063 (5)
C10	0.0491 (7)	0.0497 (7)	0.0459 (8)	−0.0045 (6)	−0.0056 (6)	0.0082 (6)
C11	0.0431 (7)	0.0486 (8)	0.0555 (8)	−0.0039 (6)	−0.0036 (6)	0.0087 (6)
C12	0.0439 (7)	0.0393 (7)	0.0486 (8)	−0.0061 (5)	0.0022 (5)	0.0063 (5)
C13	0.0443 (7)	0.0456 (7)	0.0603 (9)	−0.0009 (6)	0.0055 (6)	0.0046 (6)
C14	0.0554 (8)	0.0393 (7)	0.0577 (9)	−0.0035 (6)	0.0113 (6)	0.0000 (6)
C15	0.0579 (8)	0.0457 (7)	0.0452 (7)	−0.0057 (6)	0.0039 (6)	−0.0020 (6)
C16	0.0487 (7)	0.0418 (7)	0.0441 (7)	−0.0058 (5)	0.0003 (6)	0.0016 (5)
C17	0.0424 (7)	0.0366 (6)	0.0425 (7)	−0.0063 (5)	0.0023 (5)	0.0050 (5)
C18	0.0403 (6)	0.0414 (7)	0.0415 (7)	−0.0044 (5)	−0.0001 (5)	0.0056 (5)
C19	0.0674 (10)	0.0653 (10)	0.0681 (11)	0.0055 (8)	0.0161 (8)	−0.0080 (8)
C20	0.0544 (8)	0.0803 (11)	0.0442 (8)	0.0030 (8)	−0.0051 (6)	−0.0052 (7)
O1	0.0449 (5)	0.0695 (6)	0.0404 (5)	0.0060 (4)	−0.0017 (4)	−0.0002 (4)
O2	0.0706 (7)	0.1068 (10)	0.0479 (6)	0.0163 (7)	−0.0150 (5)	0.0029 (6)
O3	0.0486 (6)	0.1003 (10)	0.0703 (8)	0.0121 (6)	−0.0092 (5)	0.0031 (7)

Geometric parameters (Å, º)

C1—C2	1.342 (2)	C11—O3	1.2130 (17)
C1—O1	1.3721 (17)	C11—C12	1.476 (2)
C1—H1	0.9300	C12—C13	1.388 (2)
C2—C9	1.4480 (19)	C12—C17	1.4110 (19)
C2—C3	1.474 (2)	C13—C14	1.381 (2)
C3—C4	1.389 (2)	C13—H13	0.9300
C3—C8	1.391 (2)	C14—C15	1.387 (2)
C4—C5	1.383 (2)	C14—C19	1.500 (2)
C4—H4	0.9300	C15—C16	1.393 (2)
C5—C6	1.370 (3)	C15—H15	0.9300
C5—H5	0.9300	C16—C17	1.3999 (19)
C6—C7	1.375 (3)	C16—C20	1.503 (2)
C6—H6	0.9300	C17—C18	1.4538 (18)
C7—C8	1.387 (2)	C18—O1	1.3496 (16)
C7—H7	0.9300	C19—H19A	0.9600
C8—H8	0.9300	C19—H19B	0.9600
C9—C18	1.3666 (18)	C19—H19C	0.9600
C9—C10	1.4457 (19)	C20—H20A	0.9600
C10—O2	1.2105 (17)	C20—H20B	0.9600
C10—C11	1.548 (2)	C20—H20C	0.9600
C2—C1—O1	112.39 (13)	C13—C12—C11	118.62 (13)
C2—C1—H1	123.8	C17—C12—C11	120.70 (12)
O1—C1—H1	123.8	C14—C13—C12	120.77 (13)
C1—C2—C9	104.32 (12)	C14—C13—H13	119.6
C1—C2—C3	123.16 (13)	C12—C13—H13	119.6
C9—C2—C3	132.53 (12)	C13—C14—C15	117.72 (13)
C4—C3—C8	118.45 (14)	C13—C14—C19	121.81 (14)
C4—C3—C2	118.80 (13)	C15—C14—C19	120.46 (14)
C8—C3—C2	122.66 (14)	C14—C15—C16	123.84 (14)
C5—C4—C3	120.75 (16)	C14—C15—H15	118.1
C5—C4—H4	119.6	C16—C15—H15	118.1
C3—C4—H4	119.6	C15—C16—C17	117.52 (13)
C6—C5—C4	120.33 (17)	C15—C16—C20	118.41 (13)
C6—C5—H5	119.8	C17—C16—C20	124.07 (12)
C4—C5—H5	119.8	C16—C17—C12	119.40 (12)
C5—C6—C7	119.72 (17)	C16—C17—C18	125.04 (12)
C5—C6—H6	120.1	C12—C17—C18	115.55 (12)
C7—C6—H6	120.1	O1—C18—C9	110.17 (11)
C6—C7—C8	120.56 (17)	O1—C18—C17	121.37 (11)
C6—C7—H7	119.7	C9—C18—C17	128.46 (12)
C8—C7—H7	119.7	C14—C19—H19A	109.5
C7—C8—C3	120.15 (16)	C14—C19—H19B	109.5
C7—C8—H8	119.9	H19A—C19—H19B	109.5
C3—C8—H8	119.9	C14—C19—H19C	109.5
C18—C9—C10	119.23 (12)	H19A—C19—H19C	109.5
C18—C9—C2	106.88 (11)	H19B—C19—H19C	109.5
C10—C9—C2	133.87 (12)	C16—C20—H20A	109.5
O2—C10—C9	126.13 (14)	C16—C20—H20B	109.5
O2—C10—C11	118.14 (13)	H20A—C20—H20B	109.5
C9—C10—C11	115.72 (12)	C16—C20—H20C	109.5
O3—C11—C12	122.51 (14)	H20A—C20—H20C	109.5
O3—C11—C10	117.24 (13)	H20B—C20—H20C	109.5
C12—C11—C10	120.25 (12)	C18—O1—C1	106.23 (10)
C13—C12—C17	120.68 (13)
O1—C1—C2—C9	−0.80 (17)	C10—C11—C12—C17	−0.52 (19)
O1—C1—C2—C3	179.16 (12)	C17—C12—C13—C14	0.4 (2)
C1—C2—C3—C4	−31.4 (2)	C11—C12—C13—C14	−179.45 (12)
C9—C2—C3—C4	148.53 (15)	C12—C13—C14—C15	2.1 (2)
C1—C2—C3—C8	145.23 (16)	C12—C13—C14—C19	−176.95 (13)
C9—C2—C3—C8	−34.8 (2)	C13—C14—C15—C16	−2.6 (2)
C8—C3—C4—C5	−2.0 (2)	C19—C14—C15—C16	176.49 (14)
C2—C3—C4—C5	174.80 (15)	C14—C15—C16—C17	0.5 (2)
C3—C4—C5—C6	0.4 (3)	C14—C15—C16—C20	−178.85 (13)
C4—C5—C6—C7	0.8 (3)	C15—C16—C17—C12	2.02 (18)
C5—C6—C7—C8	−0.3 (3)	C20—C16—C17—C12	−178.68 (13)
C6—C7—C8—C3	−1.3 (3)	C15—C16—C17—C18	−178.94 (12)
C4—C3—C8—C7	2.4 (2)	C20—C16—C17—C18	0.4 (2)
C2—C3—C8—C7	−174.24 (14)	C13—C12—C17—C16	−2.48 (19)
C1—C2—C9—C18	1.27 (15)	C11—C12—C17—C16	177.34 (12)
C3—C2—C9—C18	−178.68 (14)	C13—C12—C17—C18	178.39 (11)
C1—C2—C9—C10	179.28 (15)	C11—C12—C17—C18	−1.80 (17)
C3—C2—C9—C10	−0.7 (3)	C10—C9—C18—O1	−179.68 (11)
C18—C9—C10—O2	178.62 (15)	C2—C9—C18—O1	−1.32 (14)
C2—C9—C10—O2	0.8 (3)	C10—C9—C18—C17	−0.2 (2)
C18—C9—C10—C11	−2.22 (18)	C2—C9—C18—C17	178.16 (12)
C2—C9—C10—C11	179.96 (13)	C16—C17—C18—O1	2.71 (19)
O2—C10—C11—O3	2.1 (2)	C12—C17—C18—O1	−178.22 (11)
C9—C10—C11—O3	−177.14 (13)	C16—C17—C18—C9	−176.72 (13)
O2—C10—C11—C12	−178.18 (14)	C12—C17—C18—C9	2.35 (19)
C9—C10—C11—C12	2.59 (19)	C9—C18—O1—C1	0.84 (15)
O3—C11—C12—C13	−1.0 (2)	C17—C18—O1—C1	−178.69 (12)
C10—C11—C12—C13	179.29 (12)	C2—C1—O1—C18	0.02 (17)
O3—C11—C12—C17	179.19 (14)