(E)-3-Hexene-1,6-diyl dibenzoate

The title mol­ecule, C₂₀H₂₀O₄, lies on an inversion center. The central alkene moiety is not coplanar with the remainder of the mol­ecule, forming a dihedral angle of 61.61 (12)° with the O-CH₂-CH₂-C plane and a dihedral angle of 58.70 (11)° with the phenyl plane. The central C=C length is 1.326 (2) Å.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.042
• wR factor = 0.113
• Data-to-parameter ratio = 22.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

During an attempted cross metathesis reaction, the title compound, (I), was produced in an interesting side reaction. Such cross metathesis reactions, which tend to be unpredictable, occur between two olefins in the presence of a Ru catalyst known as Hoyveda's catalyst (Garber et al., 2000). In the reaction, an olefin first reacts with the Ru catalyst, and then the highly reactive intermediate reacts with a different olefin. In this case, the second step was reaction of another molecule of the first olefin, but-3-enyl benzoate, to form the title dimer. The crystal structure determination was carried out in order to identify the unexpected product.

The molecule, which lies on a crystallographic inversion center, is illustrated in Fig. 1. The central 3-hexene moiety is nonplanar, with torsion angle C3—C2—C1—C1ⁱ [symmetry code: (i) = 1 − x, 1 − y, 1 − z] of −121.21 (14)°, yielding the dihedral angles given in the abstract.

The title compound has been previously reported as an intermediate in the synthesis of the corresponding 3,4-diol (Torneiro & Still, 1997).

S2. Experimental

To 15 ml tetrahydrofuran were added but-3-enyl benzoate (0.10 g., 0.56 mmol, 1 eq.), and methyl vinyl ketone (0.85 g, 11.2 mmol, 20 eq.). Hoyveda's catalyst (0.018 g, 0.028 mmol, 0.05 eq) (Garber et al., 2000) was added to the flask in 5 ml dichloromethane. The reaction mixture was stirred until complete by TLC. The reaction mixture was purified by column chromatography to obtain the title compound after removal of solvent.

S3. Refinement

Hydrogen atoms were placed in idealized positions, with C—H bond distances 0.95–0.99 Å, and thereafter treated as riding. Displacement parameters for H were assigned as U_iso = 1.2Ueq of the attached atom.

Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO and SCALEPACK; data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. The title compound, showing the atomic numbering scheme, with displacement parameters drawn at the 50% level.

(I)

Crystal data

C20H20O4	Z = 1
Mr = 324.36	F(000) = 172
Triclinic, P1	Dx = 1.270 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.829 (3) Å	Cell parameters from 2385 reflections
b = 7.508 (2) Å	θ = 2.5–30.0°
c = 9.460 (4) Å	µ = 0.09 mm^−1
α = 67.424 (17)°	T = 100 K
β = 81.663 (15)°	Plate, colorless
γ = 71.322 (16)°	0.42 × 0.37 × 0.07 mm
V = 424.1 (3) Å^3

Data collection

KappaCCD diffractometer (with Oxford Cryostream)	1979 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.021
Graphite monochromator	θmax = 30.0°, θmin = 3.1°
ω scans with κ offsets	h = −9→9
9345 measured reflections	k = −10→10
2480 independent reflections	l = −13→13

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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0517P)^2 + 0.0772P] where P = (Fo^2 + 2Fc^2)/3
2480 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.30 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
O1	0.11730 (10)	0.70498 (11)	0.12298 (8)	0.02549 (17)
O2	−0.22346 (11)	0.81072 (11)	0.17281 (8)	0.02958 (19)
C1	0.43531 (15)	0.47590 (14)	0.46947 (11)	0.0250 (2)
H1	0.3689	0.3797	0.5361	0.030*
C2	0.38650 (15)	0.56267 (15)	0.30258 (11)	0.0253 (2)
H2A	0.4299	0.4536	0.2603	0.030*
H2B	0.4647	0.6609	0.2465	0.030*
C3	0.15700 (14)	0.66633 (15)	0.27988 (11)	0.0241 (2)
H3A	0.0760	0.5787	0.3515	0.029*
H3B	0.1178	0.7943	0.2987	0.029*
C4	−0.08221 (14)	0.77226 (14)	0.08580 (11)	0.0226 (2)
C5	−0.10756 (14)	0.79355 (13)	−0.07446 (11)	0.0227 (2)
C6	−0.30669 (15)	0.86558 (15)	−0.13057 (12)	0.0263 (2)
H6	−0.4226	0.8959	−0.0660	0.032*
C7	−0.33613 (17)	0.89324 (15)	−0.28083 (12)	0.0291 (2)
H7	−0.4718	0.9449	−0.3196	0.035*
C8	−0.16690 (17)	0.84526 (15)	−0.37391 (12)	0.0302 (2)
H8	−0.1869	0.8639	−0.4765	0.036*
C9	0.03194 (17)	0.77001 (16)	−0.31778 (12)	0.0297 (2)
H9	0.1473	0.7358	−0.3816	0.036*
C10	0.06215 (15)	0.74486 (15)	−0.16834 (12)	0.0262 (2)
H10	0.1981	0.6946	−0.1302	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0179 (3)	0.0336 (4)	0.0233 (3)	−0.0050 (3)	−0.0009 (2)	−0.0104 (3)
O2	0.0215 (4)	0.0377 (4)	0.0268 (4)	−0.0053 (3)	0.0022 (3)	−0.0124 (3)
C1	0.0202 (4)	0.0246 (4)	0.0279 (5)	−0.0047 (3)	−0.0003 (3)	−0.0085 (4)
C2	0.0202 (4)	0.0283 (5)	0.0269 (5)	−0.0061 (4)	−0.0005 (3)	−0.0101 (4)
C3	0.0208 (4)	0.0276 (5)	0.0224 (5)	−0.0053 (3)	−0.0011 (3)	−0.0087 (4)
C4	0.0183 (4)	0.0222 (4)	0.0256 (5)	−0.0054 (3)	−0.0003 (3)	−0.0072 (3)
C5	0.0218 (4)	0.0202 (4)	0.0247 (5)	−0.0053 (3)	−0.0007 (3)	−0.0071 (3)
C6	0.0220 (5)	0.0257 (5)	0.0304 (5)	−0.0044 (4)	−0.0013 (4)	−0.0111 (4)
C7	0.0277 (5)	0.0271 (5)	0.0328 (5)	−0.0053 (4)	−0.0072 (4)	−0.0109 (4)
C8	0.0381 (6)	0.0270 (5)	0.0262 (5)	−0.0093 (4)	−0.0037 (4)	−0.0094 (4)
C9	0.0305 (5)	0.0300 (5)	0.0280 (5)	−0.0073 (4)	0.0037 (4)	−0.0125 (4)
C10	0.0226 (5)	0.0254 (5)	0.0280 (5)	−0.0048 (4)	0.0003 (4)	−0.0090 (4)

Geometric parameters (Å, º)

O1—C4	1.3405 (13)	C5—C6	1.3933 (14)
O1—C3	1.4479 (13)	C5—C10	1.3946 (14)
O2—C4	1.2104 (12)	C6—C7	1.3905 (15)
C1—C1^i	1.326 (2)	C6—H6	0.95
C1—C2	1.5006 (15)	C7—C8	1.3865 (16)
C1—H1	0.95	C7—H7	0.95
C2—C3	1.5153 (15)	C8—C9	1.3901 (16)
C2—H2A	0.99	C8—H8	0.95
C2—H2B	0.99	C9—C10	1.3898 (15)
C3—H3A	0.99	C9—H9	0.95
C3—H3B	0.99	C10—H10	0.95
C4—C5	1.4920 (15)
C4—O1—C3	115.89 (7)	C6—C5—C10	119.82 (10)
C1^i—C1—C2	124.60 (12)	C6—C5—C4	118.50 (9)
C1^i—C1—H1	117.7	C10—C5—C4	121.68 (9)
C2—C1—H1	117.7	C7—C6—C5	120.16 (9)
C1—C2—C3	110.66 (8)	C7—C6—H6	119.9
C1—C2—H2A	109.5	C5—C6—H6	119.9
C3—C2—H2A	109.5	C8—C7—C6	119.80 (10)
C1—C2—H2B	109.5	C8—C7—H7	120.1
C3—C2—H2B	109.5	C6—C7—H7	120.1
H2A—C2—H2B	108.1	C7—C8—C9	120.31 (10)
O1—C3—C2	106.81 (8)	C7—C8—H8	119.8
O1—C3—H3A	110.4	C9—C8—H8	119.8
C2—C3—H3A	110.4	C10—C9—C8	120.04 (10)
O1—C3—H3B	110.4	C10—C9—H9	120.0
C2—C3—H3B	110.4	C8—C9—H9	120.0
H3A—C3—H3B	108.6	C9—C10—C5	119.85 (10)
O2—C4—O1	123.51 (9)	C9—C10—H10	120.1
O2—C4—C5	124.63 (9)	C5—C10—H10	120.1
O1—C4—C5	111.86 (8)
C1^i—C1—C2—C3	−121.21 (14)	C10—C5—C6—C7	−1.46 (14)
C4—O1—C3—C2	171.48 (8)	C4—C5—C6—C7	178.05 (8)
C1—C2—C3—O1	−167.53 (7)	C5—C6—C7—C8	1.24 (15)
C3—O1—C4—O2	4.11 (14)	C6—C7—C8—C9	−0.11 (15)
C3—O1—C4—C5	−175.94 (7)	C7—C8—C9—C10	−0.80 (16)
O2—C4—C5—C6	1.05 (14)	C8—C9—C10—C5	0.58 (15)
O1—C4—C5—C6	−178.90 (8)	C6—C5—C10—C9	0.54 (15)
O2—C4—C5—C10	−179.45 (9)	C4—C5—C10—C9	−178.95 (9)
O1—C4—C5—C10	0.60 (13)

Symmetry code: (i) −x+1, −y+1, −z+1.