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Acta Cryst. (2009). E65, o2325    [ doi:10.1107/S1600536809034333 ]

Bis[5-(4-methoxybenzyl)furan-3-yl]methanone

M. Bolte, L. Schwarz and A. S. K. Hashmi

Abstract top

The title compound, C25H22O5, was obtained by a dehydrogenative carbonylation reaction. It crystallizes with one half-molecule in the asymmetric unit. The molecules have crystallographic C2 symmetry and the two atoms of the carbonyl group are located on the rotation axis. The methoxy groups are coplanar with the benzene ring to which they are attached [C-C-O-C = 1.0 (6)°]. The two furan rings are inclined at 17.3 (3)° with respect to each other and the dihedral angle between the furan ring and the benzene ring is 75.83 (12)°. The crystal structure is stabilized by C-H...O hydrogen bonds.

Comment top

The palladium-catalysed cycloisomerization of allenyl ketones delivers furan derivatives (Hashmi, 1995; Hashmi & Schwarz, 1997; Hashmi et al., 1999, 2000, 2004; Hashmi, Ruppert, Knöfel & Bats, 1997). In the context of these investigations, we also conducted the reaction of 1-(4-methoxy-phenyl)penta-3,4-dien-2-one in one atmosphere of carbon monoxide with 0.5 mol% of the PdCl2(MeCN)2 catalyst in acetonitrile. Besides starting material (7%), the monomeric cyclization product 2-(4-methoxybenzyl)furan (3%) and the cyclization/dimerization product (E)-1-[4-methoxybenzyl]-3-{5-[4-(methoxybenzyl]furan-3-yl}but-2-en-1-one (8%) as a new product type the title compound could be isolated (11%). The overall reaction to this new product type is a dehydrogenative carbonylation, mechanistic details are yet unknown.

The title compound crystallizes with half a molecule in the asymmetric unit. The molecules have crystallographic C2 symmetry and the two atoms of the carbonyl group are located on the rotation axis. The methoxy groups are coplanar with the phenyl ring to which they are attached [C3—C4—O41—C42 1.0 (6)°]. The two furan rings are inclined by 17.3 (3)° with respect to each other and the dihedral angle between the furan ring and the phenyl ring is 75.83 (12)°. The crystal structure is stabilized by C—H···O hydrogen bonds.

Related literature top

The palladium-catalysed cycloisomerization of allenyl ketones delivers furan derivatives, see: Hashmi (1995); Hashmi & Schwarz (1997); Hashmi et al. (1999, 2000, 2004); Hashmi, Ruppert, Knöfel & Bats (1997).

Experimental top

1.30 mmol (245 mg) of 1-(4-methoxy-phenyl)penta-3,4-dien-2-one were dissolved in 7.7 ml MeCN and degassed. The solution was stirred under one atmosphere of CO for two hours, then 6.6 µmol (1.7 mg) Pd(MeCN)2Cl2 in 0.3 ml MeCN were added. After stirring for 20 h at room temperature the solvent was removed in vacuo and the residue was purified by column chromatography on silica gel (eluting with hexanes/ethyl acetate, 5:1). Thus 11% (28.5 mg, 70.8 µmol) of the title compound were obtained. Rf (H/EE, 5:1) = 0.18. 1H NMR (CDCl3, 250 MHz): δ = 3.79 (s, 6 H), 3.91 (s, 4 H), 6.42 (d, J = 0.9 Hz, 2 H), 6.83- 6.88 (m, 4 H), 7.13–7.20 (m, 4 H), 7.84 (d, J = 0.9 Hz, 2 H). 13C NMR (CDCl3, 62.9 MHz): δ = 33.37 (t, 2 C), 55.14 (q, 2 C), 105.62 (d, 2 C), 113.93 (d, 4 C), 128.16 (s, 2 C), 128.81 (s, 2 C), 129.63 (d, 4 C), 145.69 (d, 2 C), 156.96 (s, 2 C), 158.37 (s, 2 C), 189.94 (s).

Refinement top

H atoms were located in a difference map but finally geometrically positioned and refined using a riding model with fixed individual displacement parameters [Uiso(H) = 1.2 Ueq(C) or Uiso(H) = 1.5 Ueq(Cmethyl)] and with Caromatic—H= 0.95 Å, Cmethyl—H = 0.98Å and Cmethylene—H = 0.99 Å.

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Sheldrick, 2008); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. Perspective view of the title compound with the atom numbering; displacement ellipsoids are at the 50% probability level. Symmetry operator for generating equivalent atoms: (A) 1 - x, y, 1/2 - z.
Bis[5-(4-methoxybenzyl)furan-3-yl]methanone top
Crystal data top
C25H22O5F(000) = 848
Mr = 402.43Dx = 1.308 Mg m−3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 5761 reflections
a = 42.050 (2) Åθ = 5.2–24.8°
b = 5.9183 (2) ŵ = 0.09 mm−1
c = 8.3269 (3) ÅT = 183 K
β = 99.594 (2)°Plate, colourless
V = 2043.29 (14) Å30.60 × 0.30 × 0.05 mm
Z = 4
Data collection top
Siemens CCD three-circle
diffractometer		1506 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.045
graphiteθmax = 26.2°, θmin = 2.0°
ω scansh = −50→51
8458 measured reflectionsk = −7→7
1854 independent reflectionsl = −10→9
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.081H-atom parameters constrained
wR(F2) = 0.195 w = 1/[σ2(Fo2) + (0.0374P)2 + 9.4535P]
where P = (Fo2 + 2Fc2)/3
S = 1.25(Δ/σ)max < 0.001
1854 reflectionsΔρmax = 0.31 e Å−3
138 parametersΔρmin = −0.23 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0039 (8)
Crystal data top
C25H22O5V = 2043.29 (14) Å3
Mr = 402.43Z = 4
Monoclinic, C2/cMo Kα radiation
a = 42.050 (2) ŵ = 0.09 mm−1
b = 5.9183 (2) ÅT = 183 K
c = 8.3269 (3) Å0.60 × 0.30 × 0.05 mm
β = 99.594 (2)°
Data collection top
Siemens CCD three-circle
diffractometer		1506 reflections with I > 2σ(I)
8458 measured reflectionsRint = 0.045
1854 independent reflectionsθmax = 26.2°
Refinement top
R[F2 > 2σ(F2)] = 0.081H-atom parameters constrained
wR(F2) = 0.195Δρmax = 0.31 e Å−3
S = 1.25Δρmin = −0.23 e Å−3
1854 reflectionsAbsolute structure: ?
138 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.37264 (9)0.2789 (7)0.4374 (5)0.0332 (9)
C20.35544 (9)0.0841 (7)0.4534 (5)0.0385 (10)
H20.3643−0.02670.53070.046*
C30.32526 (9)0.0460 (7)0.3586 (5)0.0389 (10)
H30.3137−0.08870.37160.047*
C40.31251 (9)0.2064 (7)0.2458 (5)0.0328 (9)
O410.28319 (6)0.1887 (5)0.1431 (4)0.0422 (8)
C420.26472 (10)−0.0101 (9)0.1577 (6)0.0534 (13)
H42A0.2618−0.02900.27120.080*
H42B0.2761−0.14180.12370.080*
H42C0.24360.00380.08810.080*
C50.32947 (9)0.4037 (7)0.2275 (5)0.0363 (10)
H50.32070.51420.14990.044*
C60.35934 (9)0.4378 (7)0.3238 (5)0.0364 (10)
H60.37090.57290.31140.044*
C70.40530 (9)0.3207 (8)0.5416 (5)0.0415 (11)
H7A0.40470.46800.59740.050*
H7B0.40920.20220.62650.050*
C110.43293 (9)0.3219 (7)0.4488 (5)0.0339 (9)
C120.45192 (8)0.4804 (7)0.4054 (4)0.0308 (9)
H120.45090.63730.42790.037*
C130.47441 (8)0.3727 (6)0.3184 (5)0.0297 (9)
C310.50000.4907 (9)0.25000.0297 (12)
O320.50000.6987 (7)0.25000.0418 (10)
C140.46659 (10)0.1524 (7)0.3128 (6)0.0418 (11)
H140.47740.03870.26180.050*
O150.44090 (7)0.1147 (5)0.3907 (4)0.0466 (9)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0262 (19)0.044 (2)0.032 (2)0.0024 (17)0.0115 (16)−0.0021 (18)
C20.034 (2)0.045 (3)0.037 (2)0.0054 (18)0.0087 (18)0.0062 (19)
C30.035 (2)0.039 (2)0.045 (2)−0.0023 (18)0.0119 (19)0.005 (2)
C40.0239 (18)0.041 (2)0.035 (2)0.0018 (16)0.0100 (16)−0.0027 (18)
O410.0297 (14)0.0454 (18)0.0502 (18)−0.0019 (13)0.0032 (13)0.0012 (14)
C420.040 (2)0.054 (3)0.063 (3)−0.014 (2)−0.002 (2)−0.003 (3)
C50.032 (2)0.036 (2)0.041 (2)0.0020 (17)0.0063 (18)0.0038 (18)
C60.031 (2)0.037 (2)0.044 (2)−0.0043 (17)0.0144 (18)−0.0009 (19)
C70.030 (2)0.060 (3)0.036 (2)0.000 (2)0.0095 (17)−0.001 (2)
C110.0252 (19)0.045 (2)0.031 (2)0.0035 (17)0.0023 (16)−0.0062 (18)
C120.0280 (19)0.035 (2)0.028 (2)0.0045 (16)0.0011 (16)−0.0044 (17)
C130.0245 (18)0.030 (2)0.035 (2)0.0011 (16)0.0040 (15)0.0000 (17)
C310.028 (3)0.026 (3)0.035 (3)0.0000.004 (2)0.000
O320.040 (2)0.031 (2)0.055 (3)0.0000.012 (2)0.000
C140.036 (2)0.032 (2)0.063 (3)0.0020 (18)0.023 (2)−0.002 (2)
O150.0380 (16)0.0336 (17)0.074 (2)−0.0051 (13)0.0252 (15)−0.0007 (15)
Geometric parameters (Å, °) top
C1—C21.380 (6)C6—H60.9500
C1—C61.384 (6)C7—C111.498 (5)
C1—C71.518 (5)C7—H7A0.9900
C2—C31.397 (6)C7—H7B0.9900
C2—H20.9500C11—C121.321 (6)
C3—C41.380 (6)C11—O151.380 (5)
C3—H30.9500C12—C131.433 (5)
C4—O411.383 (5)C12—H120.9500
C4—C51.390 (6)C13—C141.344 (6)
O41—C421.426 (5)C13—C311.474 (4)
C42—H42A0.9800C31—O321.231 (7)
C42—H42B0.9800C31—C13i1.474 (4)
C42—H42C0.9800C14—O151.368 (5)
C5—C61.388 (5)C14—H140.9500
C5—H50.9500
C2—C1—C6118.4 (4)C5—C6—H6119.3
C2—C1—C7121.3 (4)C11—C7—C1114.3 (3)
C6—C1—C7120.3 (4)C11—C7—H7A108.7
C1—C2—C3121.5 (4)C1—C7—H7A108.7
C1—C2—H2119.3C11—C7—H7B108.7
C3—C2—H2119.3C1—C7—H7B108.7
C4—C3—C2119.1 (4)H7A—C7—H7B107.6
C4—C3—H3120.4C12—C11—O15110.0 (3)
C2—C3—H3120.4C12—C11—C7134.5 (4)
C3—C4—O41125.1 (4)O15—C11—C7115.5 (4)
C3—C4—C5120.3 (4)C11—C12—C13107.6 (4)
O41—C4—C5114.6 (4)C11—C12—H12126.2
C4—O41—C42116.9 (3)C13—C12—H12126.2
O41—C42—H42A109.5C14—C13—C12105.7 (3)
O41—C42—H42B109.5C14—C13—C31129.5 (4)
H42A—C42—H42B109.5C12—C13—C31124.8 (4)
O41—C42—H42C109.5O32—C31—C13i118.3 (2)
H42A—C42—H42C109.5O32—C31—C13118.3 (2)
H42B—C42—H42C109.5C13i—C31—C13123.4 (5)
C6—C5—C4119.4 (4)C13—C14—O15110.5 (3)
C6—C5—H5120.3C13—C14—H14124.8
C4—C5—H5120.3O15—C14—H14124.8
C1—C6—C5121.3 (4)C14—O15—C11106.2 (3)
C1—C6—H6119.3
C6—C1—C2—C3−0.2 (6)C1—C7—C11—O15−70.6 (5)
C7—C1—C2—C3179.5 (4)O15—C11—C12—C13−1.9 (4)
C1—C2—C3—C40.4 (6)C7—C11—C12—C13179.3 (4)
C2—C3—C4—O41179.1 (4)C11—C12—C13—C141.3 (5)
C2—C3—C4—C5−0.3 (6)C11—C12—C13—C31−179.5 (3)
C3—C4—O41—C421.0 (6)C14—C13—C31—O32170.0 (4)
C5—C4—O41—C42−179.6 (4)C12—C13—C31—O32−9.0 (4)
C3—C4—C5—C60.0 (6)C14—C13—C31—C13i−10.0 (4)
O41—C4—C5—C6−179.4 (3)C12—C13—C31—C13i171.0 (4)
C2—C1—C6—C5−0.1 (6)C12—C13—C14—O15−0.2 (5)
C7—C1—C6—C5−179.8 (4)C31—C13—C14—O15−179.3 (3)
C4—C5—C6—C10.2 (6)C13—C14—O15—C11−0.9 (5)
C2—C1—C7—C11113.0 (4)C12—C11—O15—C141.8 (5)
C6—C1—C7—C11−67.3 (5)C7—C11—O15—C14−179.2 (3)
C1—C7—C11—C12108.1 (5)
Symmetry codes: (i) −x+1, y, −z+1/2.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C14—H14···O32ii0.952.233.114 (5)154
C12—H12···O15iii0.952.873.782 (5)163
Symmetry codes: (ii) x, y−1, z; (iii) x, y+1, z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C14—H14···O32i0.952.233.114 (5)154
C12—H12···O15ii0.952.873.782 (5)163
Symmetry codes: (i) x, y−1, z; (ii) x, y+1, z.
Acknowledgements top

Palladium dichloride was donated by Umicore AG & Co KG.

references
References top

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Hashmi, A. S. K., Schwarz, L. & Bats, J. (2000). Prakt. Chem. 342, 40–51.

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