organic compounds
Tetra-tert-butyl 13,14-dioxapentacyclo[8.2.1.14,7.02,9.03,8]tetradeca-5,11-diene-5,6,11,12-tetracarboxylate
aDepartment of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6, and bDepartment of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1
*Correspondence e-mail: alough@chem.utoronto.ca
The stereochemistry of the title compound, C32H44O10, at the cyclobutane ring is cis-anti-cis. The molecule lies across an inversion center. In the crystal, weak C—H⋯O hydrogen bonds connect molecules into chains along [100], forming R22(6) rings.
Related literature
For related structures, see: Lough et al. (2012a,b). For the synthetic background, see: Ballantine et al. (2009). For hydrogen-bond motifs, see: Bernstein et al. (1995).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supporting information
https://doi.org/10.1107/S1600536812039220/hb6953sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812039220/hb6953Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812039220/hb6953Isup3.cml
tert-Butoxy-7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate 1 (45 mg, 0.15 mmol) was weighed into an oven-dried vial, purged with nitrogen and transferred into a Dry Box. In the Dry Box, Cp*Ru(COD)Cl (10 mol%) was added to another oven dried vial and dissolved in 1,2-dichloroethane (0.5 ml). The Ru-catalyst was then transferred into the vial containing the 7-oxanorbornadiene. The vial was sealed with a screw cap and removed from the Dry Box. The reaction was heated at 333 K with stirring for 20 h. The crude product was purified by
(EtOAc:hexanes = 2:3) followed by recrystallization in hexanes to give the dimer (I). Colourless blocks were grown by slow evaportation of a solution of (I) in hexanes.Hydrogen atoms were placed in calculated positions with C—H distances of 0.98 and 1.00 Å. They were included in the
in a riding-model approximation with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(Cmethyl).We have recently investigated the Ru-catalyzed isomerization and dimerization reaction of oxanorbornadiene compounds (Ballantine et al., 2009). When dissolved in 1,2-dichloroethane in the presence of Cp*Ru(COD)Cl, tert-butoxy-7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate will dimerize into the title compound (I) (see Fig. 1). The desired product was resolved using fractional crystallization in hexanes. The stereochemistry of the product was determined by this single-crystal X-ray analysis and was found to have a cis-anti-cis stereochemistry at the cyclobutane ring of the dimer.
The molecular structure of (I) is shown in Fig. 2. In the crystal, weak C—H···O hydrogen bonds connect molecules into one-dimensional chains (Fig. 3) along [100] forming R22(6) rings (Bernstein et al., 1995).
For related structures see the preceding (Lough et al., 2012a) and following (Lough et al., 2012b) papers
For related structures, see: Lough et al. (2012a,b). For the synthetic background, see: Ballantine et al. (2009). For hydrogen-bond motifs, see: Bernstein et al. (1995).
Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C32H44O10 | Z = 1 |
Mr = 588.67 | F(000) = 316 |
Triclinic, P1 | Dx = 1.242 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 5.8376 (10) Å | Cell parameters from 4249 reflections |
b = 9.4895 (17) Å | θ = 2.2–27.5° |
c = 14.924 (3) Å | µ = 0.09 mm−1 |
α = 99.926 (4)° | T = 150 K |
β = 98.545 (4)° | Block, colourless |
γ = 100.462 (4)° | 0.45 × 0.25 × 0.15 mm |
V = 786.9 (2) Å3 |
Bruker Kappa APEX DUO CCD diffractometer | 3559 independent reflections |
Radiation source: fine-focus sealed tube | 3024 reflections with I > 2σ(I) |
Bruker Triumph monochromator | Rint = 0.015 |
φ and ω scans | θmax = 27.5°, θmin = 1.4° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −7→4 |
Tmin = 0.698, Tmax = 0.746 | k = −12→12 |
6490 measured reflections | l = −19→18 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.104 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0475P)2 + 0.3125P] where P = (Fo2 + 2Fc2)/3 |
3559 reflections | (Δ/σ)max = 0.001 |
196 parameters | Δρmax = 0.33 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
C32H44O10 | γ = 100.462 (4)° |
Mr = 588.67 | V = 786.9 (2) Å3 |
Triclinic, P1 | Z = 1 |
a = 5.8376 (10) Å | Mo Kα radiation |
b = 9.4895 (17) Å | µ = 0.09 mm−1 |
c = 14.924 (3) Å | T = 150 K |
α = 99.926 (4)° | 0.45 × 0.25 × 0.15 mm |
β = 98.545 (4)° |
Bruker Kappa APEX DUO CCD diffractometer | 3559 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 3024 reflections with I > 2σ(I) |
Tmin = 0.698, Tmax = 0.746 | Rint = 0.015 |
6490 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.104 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.33 e Å−3 |
3559 reflections | Δρmin = −0.21 e Å−3 |
196 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.22773 (14) | 0.65121 (9) | 0.02699 (6) | 0.01803 (19) | |
O2 | 0.35940 (19) | 0.52069 (10) | 0.29004 (7) | 0.0282 (2) | |
O3 | 0.26592 (16) | 0.74251 (10) | 0.32725 (6) | 0.0217 (2) | |
O4 | 0.68115 (18) | 0.95566 (11) | 0.29352 (7) | 0.0298 (2) | |
O5 | 0.80759 (16) | 0.97519 (9) | 0.15871 (6) | 0.0207 (2) | |
C1 | 0.3636 (2) | 0.67330 (13) | 0.18207 (8) | 0.0174 (2) | |
C2 | 0.2523 (2) | 0.55902 (13) | 0.09395 (8) | 0.0165 (2) | |
H2A | 0.1029 | 0.4910 | 0.0973 | 0.020* | |
C3 | 0.4520 (2) | 0.48426 (13) | 0.06656 (8) | 0.0154 (2) | |
H3 | 0.5361 | 0.4416 | 0.1152 | 0.018* | |
C4 | 0.6083 (2) | 0.61021 (12) | 0.03288 (8) | 0.0146 (2) | |
H4 | 0.7801 | 0.6364 | 0.0622 | 0.018* | |
C5 | 0.4701 (2) | 0.73280 (13) | 0.05005 (8) | 0.0164 (2) | |
H5A | 0.5070 | 0.8137 | 0.0160 | 0.020* | |
C6 | 0.5012 (2) | 0.78123 (13) | 0.15483 (8) | 0.0167 (2) | |
C7 | 0.3337 (2) | 0.63815 (13) | 0.27330 (8) | 0.0180 (2) | |
C8 | 0.2067 (2) | 0.72280 (14) | 0.41859 (8) | 0.0211 (3) | |
C9 | 0.4200 (3) | 0.69922 (18) | 0.48118 (10) | 0.0332 (3) | |
H9A | 0.5579 | 0.7767 | 0.4830 | 0.050* | |
H9B | 0.4535 | 0.6038 | 0.4572 | 0.050* | |
H9C | 0.3865 | 0.7020 | 0.5438 | 0.050* | |
C10 | 0.1460 (3) | 0.86826 (18) | 0.45469 (11) | 0.0375 (4) | |
H10A | 0.0047 | 0.8794 | 0.4143 | 0.056* | |
H10B | 0.2793 | 0.9481 | 0.4555 | 0.056* | |
H10C | 0.1146 | 0.8712 | 0.5176 | 0.056* | |
C11 | −0.0074 (3) | 0.59823 (18) | 0.40294 (11) | 0.0347 (3) | |
H11A | −0.1297 | 0.6103 | 0.3540 | 0.052* | |
H11B | −0.0703 | 0.5989 | 0.4603 | 0.052* | |
H11C | 0.0392 | 0.5049 | 0.3844 | 0.052* | |
C12 | 0.6722 (2) | 0.91271 (13) | 0.21227 (8) | 0.0169 (2) | |
C13 | 0.9780 (2) | 1.11711 (14) | 0.19571 (9) | 0.0212 (3) | |
C14 | 0.8388 (3) | 1.23483 (16) | 0.21650 (13) | 0.0371 (4) | |
H14A | 0.7595 | 1.2190 | 0.2685 | 0.056* | |
H14B | 0.7199 | 1.2307 | 0.1618 | 0.056* | |
H14C | 0.9469 | 1.3311 | 0.2327 | 0.056* | |
C15 | 1.1022 (3) | 1.13826 (18) | 0.11508 (11) | 0.0380 (4) | |
H15A | 0.9856 | 1.1420 | 0.0615 | 0.057* | |
H15B | 1.1795 | 1.0563 | 0.0992 | 0.057* | |
H15C | 1.2216 | 1.2301 | 0.1325 | 0.057* | |
C16 | 1.1550 (3) | 1.10905 (18) | 0.27928 (11) | 0.0344 (4) | |
H16A | 1.0756 | 1.1054 | 0.3325 | 0.052* | |
H16B | 1.2846 | 1.1957 | 0.2937 | 0.052* | |
H16C | 1.2190 | 1.0208 | 0.2655 | 0.052* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0147 (4) | 0.0190 (4) | 0.0187 (4) | 0.0016 (3) | 0.0010 (3) | 0.0033 (3) |
O2 | 0.0417 (6) | 0.0206 (5) | 0.0259 (5) | 0.0099 (4) | 0.0126 (4) | 0.0059 (4) |
O3 | 0.0300 (5) | 0.0195 (4) | 0.0184 (4) | 0.0067 (4) | 0.0118 (4) | 0.0039 (3) |
O4 | 0.0303 (5) | 0.0322 (6) | 0.0183 (5) | −0.0081 (4) | 0.0071 (4) | −0.0046 (4) |
O5 | 0.0246 (5) | 0.0151 (4) | 0.0186 (4) | −0.0039 (3) | 0.0061 (3) | 0.0003 (3) |
C1 | 0.0169 (6) | 0.0167 (6) | 0.0176 (6) | 0.0030 (4) | 0.0048 (4) | 0.0004 (4) |
C2 | 0.0154 (6) | 0.0167 (6) | 0.0158 (6) | −0.0001 (4) | 0.0041 (4) | 0.0018 (4) |
C3 | 0.0157 (6) | 0.0141 (5) | 0.0145 (6) | −0.0005 (4) | 0.0035 (4) | 0.0009 (4) |
C4 | 0.0137 (5) | 0.0144 (6) | 0.0139 (5) | −0.0002 (4) | 0.0029 (4) | 0.0009 (4) |
C5 | 0.0160 (6) | 0.0155 (6) | 0.0160 (6) | 0.0004 (4) | 0.0025 (4) | 0.0017 (4) |
C6 | 0.0169 (6) | 0.0159 (6) | 0.0166 (6) | 0.0036 (4) | 0.0045 (4) | 0.0005 (4) |
C7 | 0.0159 (6) | 0.0175 (6) | 0.0181 (6) | −0.0006 (4) | 0.0046 (4) | 0.0000 (4) |
C8 | 0.0267 (7) | 0.0247 (7) | 0.0144 (6) | 0.0071 (5) | 0.0088 (5) | 0.0045 (5) |
C9 | 0.0363 (8) | 0.0394 (8) | 0.0230 (7) | 0.0129 (6) | 0.0008 (6) | 0.0028 (6) |
C10 | 0.0595 (11) | 0.0365 (9) | 0.0257 (8) | 0.0253 (8) | 0.0185 (7) | 0.0062 (6) |
C11 | 0.0293 (8) | 0.0438 (9) | 0.0320 (8) | 0.0004 (6) | 0.0146 (6) | 0.0107 (7) |
C12 | 0.0168 (6) | 0.0155 (6) | 0.0179 (6) | 0.0024 (4) | 0.0043 (4) | 0.0022 (4) |
C13 | 0.0200 (6) | 0.0161 (6) | 0.0227 (6) | −0.0052 (5) | 0.0013 (5) | 0.0031 (5) |
C14 | 0.0375 (9) | 0.0171 (7) | 0.0513 (10) | 0.0022 (6) | 0.0024 (7) | 0.0016 (6) |
C15 | 0.0415 (9) | 0.0357 (8) | 0.0305 (8) | −0.0128 (7) | 0.0109 (6) | 0.0080 (6) |
C16 | 0.0213 (7) | 0.0430 (9) | 0.0339 (8) | −0.0044 (6) | −0.0031 (6) | 0.0137 (7) |
O1—C5 | 1.4442 (14) | C8—C10 | 1.5164 (19) |
O1—C2 | 1.4453 (14) | C8—C9 | 1.5171 (19) |
O2—C7 | 1.2135 (16) | C9—H9A | 0.9800 |
O3—C7 | 1.3220 (15) | C9—H9B | 0.9800 |
O3—C8 | 1.4892 (15) | C9—H9C | 0.9800 |
O4—C12 | 1.2010 (16) | C10—H10A | 0.9800 |
O5—C12 | 1.3402 (15) | C10—H10B | 0.9800 |
O5—C13 | 1.4840 (14) | C10—H10C | 0.9800 |
C1—C6 | 1.3421 (17) | C11—H11A | 0.9800 |
C1—C7 | 1.4839 (17) | C11—H11B | 0.9800 |
C1—C2 | 1.5253 (16) | C11—H11C | 0.9800 |
C2—C3 | 1.5401 (16) | C13—C14 | 1.513 (2) |
C2—H2A | 1.0000 | C13—C15 | 1.518 (2) |
C3—C4i | 1.5498 (16) | C13—C16 | 1.5190 (18) |
C3—C4 | 1.5686 (16) | C14—H14A | 0.9800 |
C3—H3 | 1.0000 | C14—H14B | 0.9800 |
C4—C5 | 1.5392 (16) | C14—H14C | 0.9800 |
C4—C3i | 1.5498 (16) | C15—H15A | 0.9800 |
C4—H4 | 1.0000 | C15—H15B | 0.9800 |
C5—C6 | 1.5255 (16) | C15—H15C | 0.9800 |
C5—H5A | 1.0000 | C16—H16A | 0.9800 |
C6—C12 | 1.4876 (16) | C16—H16B | 0.9800 |
C8—C11 | 1.515 (2) | C16—H16C | 0.9800 |
C5—O1—C2 | 96.18 (8) | H9A—C9—H9B | 109.5 |
C7—O3—C8 | 120.96 (10) | C8—C9—H9C | 109.5 |
C12—O5—C13 | 121.03 (10) | H9A—C9—H9C | 109.5 |
C6—C1—C7 | 134.31 (11) | H9B—C9—H9C | 109.5 |
C6—C1—C2 | 105.44 (10) | C8—C10—H10A | 109.5 |
C7—C1—C2 | 119.46 (10) | C8—C10—H10B | 109.5 |
O1—C2—C1 | 101.00 (9) | H10A—C10—H10B | 109.5 |
O1—C2—C3 | 102.44 (9) | C8—C10—H10C | 109.5 |
C1—C2—C3 | 105.96 (9) | H10A—C10—H10C | 109.5 |
O1—C2—H2A | 115.2 | H10B—C10—H10C | 109.5 |
C1—C2—H2A | 115.2 | C8—C11—H11A | 109.5 |
C3—C2—H2A | 115.2 | C8—C11—H11B | 109.5 |
C2—C3—C4i | 113.90 (9) | H11A—C11—H11B | 109.5 |
C2—C3—C4 | 100.76 (9) | C8—C11—H11C | 109.5 |
C4i—C3—C4 | 90.45 (9) | H11A—C11—H11C | 109.5 |
C2—C3—H3 | 116.0 | H11B—C11—H11C | 109.5 |
C4i—C3—H3 | 116.0 | O4—C12—O5 | 126.38 (11) |
C4—C3—H3 | 116.0 | O4—C12—C6 | 124.31 (11) |
C5—C4—C3i | 115.39 (9) | O5—C12—C6 | 109.30 (10) |
C5—C4—C3 | 101.01 (9) | O5—C13—C14 | 108.34 (11) |
C3i—C4—C3 | 89.55 (9) | O5—C13—C15 | 102.62 (10) |
C5—C4—H4 | 115.7 | C14—C13—C15 | 110.74 (13) |
C3i—C4—H4 | 115.7 | O5—C13—C16 | 111.42 (11) |
C3—C4—H4 | 115.7 | C14—C13—C16 | 112.83 (13) |
O1—C5—C6 | 101.33 (9) | C15—C13—C16 | 110.40 (12) |
O1—C5—C4 | 101.79 (9) | C13—C14—H14A | 109.5 |
C6—C5—C4 | 106.44 (9) | C13—C14—H14B | 109.5 |
O1—C5—H5A | 115.2 | H14A—C14—H14B | 109.5 |
C6—C5—H5A | 115.2 | C13—C14—H14C | 109.5 |
C4—C5—H5A | 115.2 | H14A—C14—H14C | 109.5 |
C1—C6—C12 | 129.04 (11) | H14B—C14—H14C | 109.5 |
C1—C6—C5 | 105.29 (10) | C13—C15—H15A | 109.5 |
C12—C6—C5 | 125.30 (11) | C13—C15—H15B | 109.5 |
O2—C7—O3 | 126.77 (12) | H15A—C15—H15B | 109.5 |
O2—C7—C1 | 120.41 (11) | C13—C15—H15C | 109.5 |
O3—C7—C1 | 112.71 (10) | H15A—C15—H15C | 109.5 |
O3—C8—C11 | 108.87 (10) | H15B—C15—H15C | 109.5 |
O3—C8—C10 | 101.91 (10) | C13—C16—H16A | 109.5 |
C11—C8—C10 | 111.03 (12) | C13—C16—H16B | 109.5 |
O3—C8—C9 | 110.50 (11) | H16A—C16—H16B | 109.5 |
C11—C8—C9 | 112.93 (12) | C13—C16—H16C | 109.5 |
C10—C8—C9 | 111.03 (12) | H16A—C16—H16C | 109.5 |
C8—C9—H9A | 109.5 | H16B—C16—H16C | 109.5 |
C8—C9—H9B | 109.5 | ||
C5—O1—C2—C1 | 51.53 (10) | C2—C1—C6—C5 | 0.72 (12) |
C5—O1—C2—C3 | −57.73 (10) | O1—C5—C6—C1 | 32.18 (12) |
C6—C1—C2—O1 | −33.35 (12) | C4—C5—C6—C1 | −73.86 (12) |
C7—C1—C2—O1 | 155.41 (10) | O1—C5—C6—C12 | −154.29 (11) |
C6—C1—C2—C3 | 73.14 (12) | C4—C5—C6—C12 | 99.66 (13) |
C7—C1—C2—C3 | −98.11 (12) | C8—O3—C7—O2 | −1.27 (19) |
O1—C2—C3—C4i | −61.22 (11) | C8—O3—C7—C1 | 174.85 (10) |
C1—C2—C3—C4i | −166.66 (9) | C6—C1—C7—O2 | −123.53 (16) |
O1—C2—C3—C4 | 34.11 (10) | C2—C1—C7—O2 | 44.64 (17) |
C1—C2—C3—C4 | −71.33 (11) | C6—C1—C7—O3 | 60.08 (18) |
C2—C3—C4—C5 | 1.36 (10) | C2—C1—C7—O3 | −131.75 (11) |
C4i—C3—C4—C5 | 115.81 (10) | C7—O3—C8—C11 | −63.78 (15) |
C2—C3—C4—C3i | −114.45 (10) | C7—O3—C8—C10 | 178.84 (12) |
C4i—C3—C4—C3i | 0.0 | C7—O3—C8—C9 | 60.78 (15) |
C2—O1—C5—C6 | −51.21 (10) | C13—O5—C12—O4 | −4.86 (19) |
C2—O1—C5—C4 | 58.47 (10) | C13—O5—C12—C6 | 173.80 (10) |
C3i—C4—C5—O1 | 58.36 (12) | C1—C6—C12—O4 | −14.3 (2) |
C3—C4—C5—O1 | −36.43 (10) | C5—C6—C12—O4 | 173.77 (12) |
C3i—C4—C5—C6 | 164.08 (10) | C1—C6—C12—O5 | 167.03 (12) |
C3—C4—C5—C6 | 69.28 (11) | C5—C6—C12—O5 | −4.92 (16) |
C7—C1—C6—C12 | −3.2 (2) | C12—O5—C13—C14 | −67.15 (15) |
C2—C1—C6—C12 | −172.48 (11) | C12—O5—C13—C15 | 175.69 (12) |
C7—C1—C6—C5 | 170.05 (13) | C12—O5—C13—C16 | 57.55 (16) |
Symmetry code: (i) −x+1, −y+1, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2A···O1ii | 1.00 | 2.47 | 3.2118 (16) | 130 |
Symmetry code: (ii) −x, −y+1, −z. |
Experimental details
Crystal data | |
Chemical formula | C32H44O10 |
Mr | 588.67 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 150 |
a, b, c (Å) | 5.8376 (10), 9.4895 (17), 14.924 (3) |
α, β, γ (°) | 99.926 (4), 98.545 (4), 100.462 (4) |
V (Å3) | 786.9 (2) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.45 × 0.25 × 0.15 |
Data collection | |
Diffractometer | Bruker Kappa APEX DUO CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.698, 0.746 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6490, 3559, 3024 |
Rint | 0.015 |
(sin θ/λ)max (Å−1) | 0.651 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.104, 1.04 |
No. of reflections | 3559 |
No. of parameters | 196 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.33, −0.21 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2A···O1i | 1.00 | 2.47 | 3.2118 (16) | 130 |
Symmetry code: (i) −x, −y+1, −z. |
Acknowledgements
The University of Toronto thanks NSERC Canada for funding.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
We have recently investigated the Ru-catalyzed isomerization and dimerization reaction of oxanorbornadiene compounds (Ballantine et al., 2009). When dissolved in 1,2-dichloroethane in the presence of Cp*Ru(COD)Cl, tert-butoxy-7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate will dimerize into the title compound (I) (see Fig. 1). The desired product was resolved using fractional crystallization in hexanes. The stereochemistry of the product was determined by this single-crystal X-ray analysis and was found to have a cis-anti-cis stereochemistry at the cyclobutane ring of the dimer.
The molecular structure of (I) is shown in Fig. 2. In the crystal, weak C—H···O hydrogen bonds connect molecules into one-dimensional chains (Fig. 3) along [100] forming R22(6) rings (Bernstein et al., 1995).
For related structures see the preceding (Lough et al., 2012a) and following (Lough et al., 2012b) papers