(2E,6E)-2,6-Difurfuryl­idene­cyclo­hexa­none

The complete mol­ecule of the title compound, C₁₆H₁₄O₃, is generated by crystallographic mirror symmetry, with two C atoms and one O atom lying on the mirror plane. The mol­ecule adopts an E configuration about the C=C bond and the dihedral angle between the furan rings is 16.1 (2)°.

Related literature

For general background to the use of bis­(aryl­methyl­idene)cyclo­alkanones as building blocks for the synthesis of biologically active heterocycles, see: Guilford et al. (1999). For related structures, see: Liu & Chen (2009); Liu (2009); Shi et al. (2008).

Experimental

Crystal data

• C₁₆H₁₄O₃

• M_r = 254.27

• Orthorhombic, P n m a

• a = 7.7313 (11) Å

• b = 15.658 (2) Å

• c = 10.3388 (14) Å

• V = 1251.5 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 295 K

• 0.15 × 0.10 × 0.06 mm

Data collection

• Siemens SMART CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.986, T_max = 0.995

• 6025 measured reflections

• 1158 independent reflections

• 731 reflections with I > 2σ(I)

• R_int = 0.072

Refinement

• R[F² > 2σ(F²)] = 0.047

• wR(F²) = 0.122

• S = 1.03

• 1158 reflections

• 92 parameters

• H-atom parameters constrained

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.16 e Å⁻³

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

Bis(arylmethylidene)cycloalkanones are widely used as building blocks for the synthesis of biologically active heterocycles (Guilford et al., 1999). In the present paper, we describe the crystal stucture of the title compound. The molecule posseses normal geometric parameters and adopts an E-configuration about the central olefinic bonds (Fig. 1). The cyclohexanone ring and the furan rings are alomst coplanar which allows conjugation. Similar structures have been observed in the related substituted cyclopentanone and cyclohexanone analogues reported by Liu & Chen (2009); Liu (2009); Shi et al. (2008).

Related literature

For general background to the use of bis(arylmethylidene)cycloalkanones as building blocks for the synthesis of biologically active heterocycles, see: Guilford et al. (1999). For related structures, see: Liu & Chen (2009); Liu (2009); Shi et al. (2008).

S2. Experimental

Tetrabutylammonium bromide (0.5 mmol) and NaOH (10 mmol) were dissolved in the mixture of water (10 ml) and ethanol (4 ml). The solution was stirred at room temperature for 10 min, followed by dropwise addition of a mixture of furaldehyde (20 mmol) and cyclohexanone (10 mmol).The mixture was stirred at the temperature of 303 K for 2 h. When the reaction was complete, the residue was filtered. The precipitate was washed by water and recrystallized from ethyl acetate to yield yellow blocks of (I). Analysis calculated for C₁₆H₁₄O₃: C 75.59, H 5.51%; found: C 75.65, H 5.46%.

S3. Refinement

All H-atoms were initially located in a difference Fourier map and were placed in geometrically idealized positions, with C—H = 0.93 - 0.97 Å and refined as riding with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 30% probability level. Atoms with the suffix A are generated by (x, 3/2–y, z).

(2E,6E)-2,6-Difurfurylidenecyclohexanone

Crystal data

C16H14O3	Dx = 1.349 Mg m^−3
Mr = 254.27	Melting point: 417 K
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 472 reflections
a = 7.7313 (11) Å	θ = 2.6–19.2°
b = 15.658 (2) Å	µ = 0.09 mm^−1
c = 10.3388 (14) Å	T = 295 K
V = 1251.5 (3) Å^3	Block, yellow
Z = 4	0.15 × 0.10 × 0.06 mm
F(000) = 536

Data collection

Siemens SMART CCD diffractometer	1158 independent reflections
Radiation source: fine-focus sealed tube	731 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.072
ω scans	θmax = 25.1°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.986, Tmax = 0.995	k = −15→18
6025 measured reflections	l = −12→9

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)] = 0.047	H-atom parameters constrained
wR(F^2) = 0.122	w = 1/[σ^2(Fo^2) + (0.0454P)^2 + 0.2592P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
1158 reflections	Δρmax = 0.17 e Å^−3
92 parameters	Δρmin = −0.16 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: 0.017 (2)

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	0.0245 (3)	0.7500	0.0550 (2)	0.0606 (7)
O2	0.1187 (2)	0.44953 (11)	0.12636 (15)	0.0689 (6)
C1	0.0568 (4)	0.7500	0.1720 (3)	0.0461 (8)
C2	0.0806 (3)	0.66875 (14)	0.24340 (19)	0.0434 (6)
C3	0.0950 (3)	0.67029 (14)	0.3886 (2)	0.0509 (7)
H3A	0.2160	0.6668	0.4129	0.061*
H3B	0.0367	0.6206	0.4239	0.061*
C4	0.0172 (4)	0.7500	0.4467 (3)	0.0527 (9)
H4A	0.0366	0.7500	0.5394	0.063*
H4B	−0.1067	0.7500	0.4319	0.063*
C5	0.0954 (3)	0.59655 (14)	0.1739 (2)	0.0494 (6)
H5	0.0794	0.6022	0.0852	0.059*
C6	0.1324 (3)	0.51243 (15)	0.2189 (2)	0.0497 (7)
C7	0.1845 (4)	0.47563 (15)	0.3310 (2)	0.0602 (7)
H7	0.2048	0.5036	0.4089	0.072*
C8	0.2024 (4)	0.38729 (16)	0.3081 (2)	0.0646 (8)
H8	0.2366	0.3460	0.3674	0.078*
C9	0.1606 (4)	0.37468 (17)	0.1841 (3)	0.0729 (9)
H9	0.1603	0.3218	0.1432	0.087*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0879 (19)	0.0532 (15)	0.0406 (13)	0.000	−0.0145 (12)	0.000
O2	0.1102 (16)	0.0485 (11)	0.0481 (10)	0.0097 (10)	0.0021 (10)	−0.0052 (8)
C1	0.051 (2)	0.051 (2)	0.0365 (17)	0.000	−0.0044 (15)	0.000
C2	0.0445 (14)	0.0456 (14)	0.0402 (12)	−0.0018 (11)	−0.0005 (10)	−0.0007 (11)
C3	0.0656 (17)	0.0479 (14)	0.0391 (12)	−0.0026 (13)	−0.0014 (11)	0.0010 (11)
C4	0.061 (2)	0.059 (2)	0.0387 (17)	0.000	0.0036 (16)	0.000
C5	0.0538 (15)	0.0524 (16)	0.0421 (13)	−0.0002 (12)	−0.0027 (11)	0.0021 (11)
C6	0.0596 (17)	0.0451 (14)	0.0445 (13)	−0.0001 (12)	0.0003 (11)	−0.0024 (11)
C7	0.0767 (19)	0.0525 (16)	0.0513 (14)	−0.0008 (14)	−0.0073 (13)	−0.0004 (12)
C8	0.081 (2)	0.0479 (16)	0.0650 (17)	0.0033 (14)	0.0018 (15)	0.0110 (13)
C9	0.109 (2)	0.0432 (16)	0.0669 (18)	0.0100 (16)	0.0138 (17)	0.0018 (14)

Geometric parameters (Å, º)

O1—C1	1.235 (3)	C4—H4A	0.9700
O2—C9	1.355 (3)	C4—H4B	0.9700
O2—C6	1.377 (2)	C5—C6	1.426 (3)
C1—C2^i	1.482 (3)	C5—H5	0.9300
C1—C2	1.482 (3)	C6—C7	1.355 (3)
C2—C5	1.344 (3)	C7—C8	1.410 (3)
C2—C3	1.506 (3)	C7—H7	0.9300
C3—C4	1.510 (3)	C8—C9	1.336 (3)
C3—H3A	0.9700	C8—H8	0.9300
C3—H3B	0.9700	C9—H9	0.9300
C4—C3^i	1.510 (3)
C9—O2—C6	107.08 (19)	C3^i—C4—H4B	109.3
O1—C1—C2^i	120.85 (13)	H4A—C4—H4B	108.0
O1—C1—C2	120.85 (13)	C2—C5—C6	128.3 (2)
C2^i—C1—C2	118.2 (3)	C2—C5—H5	115.9
C5—C2—C1	117.8 (2)	C6—C5—H5	115.9
C5—C2—C3	122.7 (2)	C7—C6—O2	108.2 (2)
C1—C2—C3	119.5 (2)	C7—C6—C5	137.0 (2)
C2—C3—C4	112.3 (2)	O2—C6—C5	114.73 (19)
C2—C3—H3A	109.1	C6—C7—C8	107.6 (2)
C4—C3—H3A	109.1	C6—C7—H7	126.2
C2—C3—H3B	109.1	C8—C7—H7	126.2
C4—C3—H3B	109.1	C9—C8—C7	106.4 (2)
H3A—C3—H3B	107.9	C9—C8—H8	126.8
C3—C4—C3^i	111.5 (3)	C7—C8—H8	126.8
C3—C4—H4A	109.3	C8—C9—O2	110.7 (2)
C3^i—C4—H4A	109.3	C8—C9—H9	124.7
C3—C4—H4B	109.3	O2—C9—H9	124.7
O1—C1—C2—C5	11.1 (4)	C9—O2—C6—C7	0.9 (3)
C2^i—C1—C2—C5	−166.16 (18)	C9—O2—C6—C5	179.0 (2)
O1—C1—C2—C3	−171.5 (3)	C2—C5—C6—C7	−10.1 (5)
C2^i—C1—C2—C3	11.2 (4)	C2—C5—C6—O2	172.5 (2)
C5—C2—C3—C4	−161.0 (2)	O2—C6—C7—C8	−0.5 (3)
C1—C2—C3—C4	21.8 (3)	C5—C6—C7—C8	−178.0 (3)
C2—C3—C4—C3^i	−55.1 (3)	C6—C7—C8—C9	0.0 (3)
C1—C2—C5—C6	174.6 (2)	C7—C8—C9—O2	0.6 (3)
C3—C2—C5—C6	−2.7 (4)	C6—O2—C9—C8	−0.9 (3)

Symmetry code: (i) x, −y+3/2, z.