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Acta Crystallogr Sect E Struct Rep Online. 2008 July 1; 64(Pt 7): o1261.
Published online 2008 June 13. doi:  10.1107/S1600536808017248
PMCID: PMC2961841

(1RS,4SR)-3-Dichloro­methyl­ene-1,4-dimethyl-2-oxabicyclo­[2.2.2]oct-5-ene

Abstract

X-ray crystallography was used to confirm the structure of the enantio-enriched title compound, C10H12Cl2O, a bicylic enol ether. A bridged boat-like structure is adopted and the dichloro­methyl­ene C atom is positioned significantly removed from the core bicyclic unit. In the crystal structure, mol­ecules pack to form sheets approximately perpendicular to the a and c axes.

Related literature

For related literature, see: Yamabe et al. (1996 [triangle]); Machiguchi et al. (1999 [triangle]); Khanjin et al. (1999 [triangle]); Ussing et al. (2006 [triangle]); Robertson & Fowler (2006 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1261-scheme1.jpg

Experimental

Crystal data

  • C10H12Cl2O
  • M r = 219.11
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1261-efi1.jpg
  • a = 9.3365 (1) Å
  • b = 9.6327 (2) Å
  • c = 11.4259 (2) Å
  • β = 92.7347 (11)°
  • V = 1026.43 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.59 mm−1
  • T = 150 K
  • 0.44 × 0.32 × 0.18 mm

Data collection

  • Nonius KappaCCD diffractometer
  • Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997 [triangle]) T min = 0.83, T max = 0.90
  • 4320 measured reflections
  • 2321 independent reflections
  • 2094 reflections with I > 2σ(I)
  • R int = 0.021

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034
  • wR(F 2) = 0.093
  • S = 1.01
  • 2321 reflections
  • 118 parameters
  • 2 restraints
  • H-atom parameters constrained
  • Δρmax = 0.36 e Å−3
  • Δρmin = −0.38 e Å−3

Data collection: COLLECT (Nonius, 2001 [triangle]); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997 [triangle]); data reduction: Görbitz (1999 [triangle]) and DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 [triangle]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 [triangle]); molecular graphics: CAMERON (Watkin et al., 1996 [triangle]); software used to prepare material for publication: CRYSTALS.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808017248/lh2637sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808017248/lh2637Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank the Oxford Chemical Crystallography Service for use of instrumentation and Dr Amber L. Thompson for her advice.

supplementary crystallographic information

Comment

The reaction between dienes and ketenes to produce cyclobutanones was long considered to be a textbook example of a [2 + 2] cycloaddition that could be understood in terms of a π2s + π2aWoodward–Hoffmann formalism. More recently, evidence has been presented for a stepwise hetero-Diels–Alder/Claisen rearrangement pathway (Yamabe et al., 1996) and it was reported that the periselectivity of these cycloadditions is responsive to the nature of the diene (Machiguchi et al., 1999). The situation is, however, more complex and a combined theoretical and experimental study of the reaction of cyclopentadiene with either dichloro- or diphenylketene revealed that both [4 + 2] and [2 + 2] adducts may be produced directly through parallel reaction pathways traversing a bifurcating energy surface (Ussing et al. 2006). Our studies sought to address certain mechanistic aspects of the Claisen rearrangement of bicyclic enol ethers structurally analogous to those produced in diene/ketene [4 + 2] cycloadditions (Robertson & Fowler, 2006); within this study, although crystals were obtained as a racemate, the title compound was prepared in an enantioenriched form in order to determine if access to non-racemic cyclobutanones could be achieved.

The relationship between computed distances of reacting termini and activation energies has been discussed for structurally similar Claisen precursors in the context of the mechanism of chorismate mutase (Khanjin et al., 1999). The molecular stucture (Fig. 1) shows the dichloromethylene carbon to be significantly removed from the carbon at C5 (3.5523 Å) and yet the title compound can be induced to undergo the Claisen rearrangement under mild thermal conditions to yield (1RS, 6SR)-8,8-dichloro-3,6-dimethylbicyclo[4.2.0]oct-3-en-7-one. Also of note are the sheets of molecules which form approximatedly perpendicular to the a- and c-axes as shown in Fig. 2 and Fig. 3.

Experimental

The title compound was crystallized by concentration of a sample dissolved in petroleum ether. [α]D25-36.1 (CHCl3, c = 1.0).

Refinement

Changes in illuminated volume were kept to a minimum, and were taken into account (Görbitz, 1999) by the multi-scan inter-frame scaling (DENZO/SCALEPACK, Otwinowski & Minor, 1997).

The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically. The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C—H in the range 0.93–0.98) and Uiso(H) (in the range 1.2–1.5 times Ueq of the parent atom), after which the positions were refined with riding constraints.

Figures

Fig. 1.
The title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitary radius.
Fig. 2.
The title compound viewed along the a-axis with H atoms omitted.
Fig. 3.
The title compound viewed along the b-axis with H atoms omitted.

Crystal data

C10H12Cl2O1F000 = 456
Mr = 219.11Dx = 1.418 Mg m3
Monoclinic, P21/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 15784 reflections
a = 9.3365 (1) Åθ = 5–27º
b = 9.6327 (2) ŵ = 0.59 mm1
c = 11.4259 (2) ÅT = 150 K
β = 92.7347 (11)ºPrism, colourless
V = 1026.43 (3) Å30.44 × 0.32 × 0.18 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer2094 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.021
T = 150 Kθmax = 27.4º
ω scansθmin = 5.1º
Absorption correction: multi-scan(DENZO/SCALEPACK; Otwinowski & Minor, 1997)h = −12→12
Tmin = 0.83, Tmax = 0.90k = −12→12
4320 measured reflectionsl = −14→14
2321 independent reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.034H-atom parameters constrained
wR(F2) = 0.093  Method = Modified Sheldrick w = 1/[σ2(F2) + (0.05P)2 + 0.71P], where P = [max(Fo2,0) + 2Fc2]/3
S = 1.01(Δ/σ)max = 0.001
2321 reflectionsΔρmax = 0.36 e Å3
118 parametersΔρmin = −0.38 e Å3
2 restraintsExtinction correction: None

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
C10.02322 (16)0.72676 (17)0.56170 (14)0.0234
O20.12271 (11)0.62312 (12)0.61475 (10)0.0217
C30.26458 (15)0.64956 (16)0.59821 (13)0.0192
C40.28716 (17)0.77747 (17)0.52291 (14)0.0230
C50.21390 (19)0.89526 (18)0.58719 (15)0.0293
C60.07027 (19)0.86685 (17)0.60962 (15)0.0274
C70.04601 (18)0.72396 (18)0.43089 (14)0.0280
C80.19575 (18)0.75082 (18)0.40893 (14)0.0267
C9−0.12456 (17)0.6806 (2)0.59357 (17)0.0326
C100.44060 (19)0.8143 (2)0.49372 (17)0.0339
C110.35800 (16)0.56064 (17)0.64983 (14)0.0215
Cl120.29697 (4)0.42007 (4)0.72783 (4)0.0295
Cl130.54194 (4)0.56859 (5)0.64989 (4)0.0320
H510.26310.97750.61230.0403*
H610.00730.92650.65090.0362*
H71−0.02140.79250.39070.0397*
H720.01580.63440.39980.0386*
H810.19900.82930.35870.0379*
H820.23470.67120.36750.0381*
H91−0.19170.74920.56520.0477*
H92−0.12610.67240.68040.0498*
H93−0.15290.59410.55900.0483*
H1010.43190.89760.44400.0529*
H1020.50320.83740.56080.0543*
H1030.48640.74090.44720.0531*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0213 (7)0.0229 (7)0.0254 (8)0.0045 (6)−0.0044 (6)−0.0009 (6)
O20.0175 (5)0.0225 (6)0.0251 (5)0.0016 (4)0.0005 (4)0.0041 (4)
C30.0188 (7)0.0205 (7)0.0183 (7)−0.0023 (5)0.0005 (5)−0.0019 (6)
C40.0257 (7)0.0220 (7)0.0209 (7)−0.0043 (6)−0.0022 (5)0.0018 (6)
C50.0373 (8)0.0221 (8)0.0275 (8)0.0009 (7)−0.0073 (7)−0.0031 (7)
C60.0339 (8)0.0229 (8)0.0251 (8)0.0055 (7)−0.0030 (6)−0.0032 (6)
C70.0347 (8)0.0264 (8)0.0223 (8)0.0014 (7)−0.0067 (6)−0.0013 (6)
C80.0352 (8)0.0268 (8)0.0178 (7)−0.0025 (7)−0.0026 (6)0.0010 (6)
C90.0212 (8)0.0328 (9)0.0435 (10)0.0028 (7)−0.0005 (7)−0.0031 (8)
C100.0309 (9)0.0345 (10)0.0360 (9)−0.0126 (7)−0.0013 (7)0.0072 (8)
C110.0189 (7)0.0234 (7)0.0222 (7)−0.0011 (6)0.0001 (5)0.0004 (6)
Cl120.0292 (2)0.0261 (2)0.0329 (2)−0.00012 (15)−0.00257 (16)0.01006 (16)
Cl130.0183 (2)0.0372 (3)0.0401 (3)0.00107 (15)−0.00273 (16)0.00256 (18)

Geometric parameters (Å, °)

C1—O21.4741 (18)C7—C81.455 (2)
C1—C61.514 (2)C7—H711.008
C1—C71.520 (2)C7—H720.970
C1—C91.511 (2)C8—H810.950
O2—C31.3707 (17)C8—H820.980
C3—C41.523 (2)C9—H910.957
C3—C111.339 (2)C9—H920.996
C4—C51.531 (2)C9—H930.954
C4—C81.544 (2)C10—H1010.985
C4—C101.528 (2)C10—H1020.968
C5—C61.404 (3)C10—H1030.993
C5—H510.953C11—Cl121.7324 (16)
C6—H610.962C11—Cl131.7190 (15)
O2—C1—C6106.78 (12)C1—C7—H72108.9
O2—C1—C7106.10 (12)C8—C7—H72111.1
C6—C1—C7108.65 (14)H71—C7—H72104.6
O2—C1—C9105.44 (13)C4—C8—C7112.39 (13)
C6—C1—C9115.34 (14)C4—C8—H81110.2
C7—C1—C9113.84 (14)C7—C8—H81107.7
C1—O2—C3114.30 (12)C4—C8—H82109.5
O2—C3—C4112.89 (12)C7—C8—H82109.0
O2—C3—C11115.71 (13)H81—C8—H82107.9
C4—C3—C11131.40 (14)C1—C9—H91107.8
C3—C4—C5104.57 (13)C1—C9—H92108.7
C3—C4—C8104.84 (12)H91—C9—H92110.5
C5—C4—C8106.63 (13)C1—C9—H93113.3
C3—C4—C10117.88 (14)H91—C9—H93107.4
C5—C4—C10112.19 (14)H92—C9—H93109.1
C8—C4—C10109.92 (13)C4—C10—H101105.3
C4—C5—C6113.31 (14)C4—C10—H102114.7
C4—C5—H51122.7H101—C10—H102107.4
C6—C5—H51123.9C4—C10—H103112.5
C1—C6—C5111.77 (14)H101—C10—H103107.3
C1—C6—H61122.4H102—C10—H103109.2
C5—C6—H61125.8C3—C11—Cl12120.21 (12)
C1—C7—C8110.31 (13)C3—C11—Cl13126.97 (12)
C1—C7—H71108.8Cl12—C11—Cl13112.82 (9)
C8—C7—H71112.9

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH2637).

References

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