Tetra­methyl 1,4-dimethyl-13,14-dioxa­penta­cyclo­[8.2.1.14,7.02,9.03,8]tetra­deca-5,11-diene-5,6,11,12-tetra­carboxyl­ate

Alan J Lough; Kelsey Jack; William Tam

doi:10.1107/S1600536812039219

. 2012 Sep 22;68(Pt 10):o2961. doi: 10.1107/S1600536812039219

Tetramethyl 1,4-dimethyl-13,14-dioxapentacyclo[8.2.1.1^4,7.0^2,9.0^3,8]tetradeca-5,11-diene-5,6,11,12-tetracarboxylate

Alan J Lough ^a,^*, Kelsey Jack ^b, William Tam ^b

PMCID: PMC3470330 PMID: 23125743

Abstract

In the title compound, C₂₂H₂₄O₁₄, the relative stereochemistry at the cyclobutane ring is cis-anti-cis and the methyl groups in the bicyclic rings are syn to each other. The two carboxylate groups attached to the same —C=C— bond are disordered over two sets of sites in a 0.603 (2):0.397 (2) ratio. In the crystal, weak C—H⋯O hydrogen bonds connect molecules into C(12) chains along [001] incorporating R ₂ ² ₂(10) 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

C₂₂H₂₄O₁₀
M _r = 448.41
Orthorhombic,
a = 11.5170 (14) Å
b = 13.9586 (15) Å
c = 26.413 (3) Å
V = 4246.1 (8) Å³
Z = 8
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 147 K
0.33 × 0.22 × 0.06 mm

Data collection

Bruker Kappa APEX DUO CCD diffractometer
Absorption correction: multi-scan (Bruker, 2007 ▶) T _min = 0.964, T _max = 0.993
19411 measured reflections
4850 independent reflections
2974 reflections with I > 2σ(I)
R _int = 0.055

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.096
S = 0.90
4850 reflections
322 parameters
32 restraints
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: 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 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812039219/hb6952sup1.cif

e-68-o2961-sup1.cif^{(37.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812039219/hb6952Isup2.hkl

e-68-o2961-Isup2.hkl^{(237.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812039219/hb6952Isup3.cml

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H10A⋯O2ⁱ	1.00	2.45	3.332 (2)	146
C14—H14C⋯O7ⁱⁱ	0.98	2.48	3.063 (3)	118

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The University of Toronto thanks NSERC Canada for funding.

supplementary crystallographic information

Comment

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, 1-methyl-2,3-dimethyl-7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate will dimerize into (I) (Fig. 1). The desired product was resolved using fractional crystallization in methanol. The stereochemistry and regioschemistry of the product was determined by this single-crystal X-ray analysis. The only dimer product obtained was found to have a cis-anti-cis stereochemistry at the cyclobutane ring of the dimer, and the two Me groups in the bicyclic rings were found to be syn to each other.

The molecular structure of (I) is shown in Fig. 2. Two of the carboxylate groups attached to the same –C═C– bond were refined as disordered over two sets of sites with refined occupancies 0.603 (2) and 0.397 (2). In the crystal, weak C—H···O hydrogen bonds connect molecules into C(12) chains (Bernstein et al., 1995) along [001] (Fig. 3) incorporating R²₂(10) rings.

Related structures (Lough et al., 2012a,b) are reported in the two following papers.

Experimental

1-Methyl-2,3-dimethyl-7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate (45 mg, 0.20 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 (0.3 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 18 h. The crude product was purified by column chromatography (EtOAc:hexanes=2:3) followed by recrystallization in hexanes to give the dimer (I). Slow evapotation of a solution of (I) in hexanes gave colourless plates.