anti-1′,6′,7′,8′,9′,14′,15′,16′-Octa­chloro­dispiro­[1,3-dioxolane-2,17′-penta­cyclo­[12.2.1.16,9.02,13.05,10]octa­decane-18′,2′′-1,3-dioxolane]-7′,15′-diene

Megan E Tenbusch; Matthew D Brooker; Jacob C Timmerman; Daniel S Jones; Markus Etzkorn

doi:10.1107/S1600536810024669

. 2010 Jul 3;66(Pt 8):o1882. doi: 10.1107/S1600536810024669

anti-1′,6′,7′,8′,9′,14′,15′,16′-Octachlorodispiro[1,3-dioxolane-2,17′-pentacyclo[12.2.1.1^6,9.0^2,13.0^5,10]octadecane-18′,2′′-1,3-dioxolane]-7′,15′-diene

Megan E Tenbusch ^a, Matthew D Brooker ^a, Jacob C Timmerman ^a, Daniel S Jones ^a,^*, Markus Etzkorn ^a,^*

PMCID: PMC3007477 PMID: 21588218

Abstract

The title compound, C₂₂H₂₀Cl₈O₄, was prepared as part of the synthesis of precursors for the preparation of fluorinated molecular tweezers. The molecule sits on an inversion center, thus requiring that the cyclooctane ring adopt a chair conformation.

Related literature

For related structures, see: Garcia et al. (1991b ▶,c ▶). For related chemistry on analogous polycyclic scaffolds, see: Garcia et al. (1991a ▶); Chou et al. (2005 ▶)

Experimental

Crystal data

C₂₂H₂₀Cl₈O₄
M _r = 631.98
Monoclinic,
a = 9.5332 (7) Å
b = 7.9121 (6) Å
c = 17.014 (2) Å
β = 101.099 (8)°
V = 1259.3 (2) Å³
Z = 2
Cu Kα radiation
μ = 8.44 mm⁻¹
T = 295 K
0.25 × 0.20 × 0.08 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: multi-scan (Blessing, 1995 ▶) T _min = 0.190, T _max = 0.561
4703 measured reflections
2275 independent reflections
1702 reflections with I > 2σ(I)
R _int = 0.047
3 standard reflections every 62 reflections intensity decay: 13%

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.118
S = 1.05
2275 reflections
155 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.47 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: DIRDIF08 (Beurskens et al., 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810024669/jh2171sup1.cif

e-66-o1882-sup1.cif^{(15.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810024669/jh2171Isup2.hkl

e-66-o1882-Isup2.hkl^{(109.6KB, hkl)}

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

Acknowledgments

This work was supported in part by funds provided by The University of North Carolina at Charlotte.

supplementary crystallographic information

Comment

The twofold Diels-Alder reaction of cyclooctadiene 1 with two equivalents of cyclopentadiene or cyclopentadienone derivatives (2a-c) furnishes the corresponding polycyclic bisadducts endo,endo,syn-3 and endo,endo,anti- 4 in a 1:4 ratio (Garcia et al., 1991a,b,c). For the synthesis of compounds with new luminescent properties (Chou et al., 2005) or the construction of molecular tweezers syn derivative 3 is an ideal starting material with the required orientation of both double bonds on one side of the molecule. Nevertheless, the separation of syn isomer 3c from anti ketal 4c prior to subsequent functionalization was often unsatisfactory in our hands. Thus, we converted cyclooctadiene 1 with the spiroketal 2 d to the spiropolycyclic bisadducts 3 d and 4 d in 85–90% yield, typically with an isomer distribution that did not differ significantly from the non-spirocyclic ketal case (1+2c). Furthermore, compound 3 d was easily separated from anti-isomer 4 d by repeated recrystallization from hot diethyl ether, i.e., the ether solution becomes more enriched in syn-isomer 3 d, and initially the clean anti-isomer 4 d precipitates upon cooling. We were able to grow single crystals of 4 d from chloroform and determined the crystal structure of compound 4 d, thus confirming the correct spectroscopic assignment of both isomers.

Two closely related structures have been found. The first (Garcia et al., 1991b) has an open ketal structure on each of the bridgehead carbon atoms, while the second (Garcia et al., 1991c) has no substituents on the bridgehead carbon atoms. Each of these two structures sits on an inversion center and thus assumes a conformation nearly identical to that of the title compound.

Experimental

A mixture of cyclooctadiene 1 (3 g, 29 mmol) and spiroketal 2 d (15 g, 57 mmol) was refluxed in toluene (5 ml) for three hours. The beige paste was filtered, washed with methylene chloride (70 ml), dried and washed again with methanol (ca 15 ml) to remove small amounts of the mono-Diels-Alder adduct. The remaining colorless solid (14.5 g, 83%) contained a 1:4 mixture of 3 d and 4 d, respectively. After one recrystallization from hot diethyl ether the pure anti-isomer 4 d was obtained as a colorless precipitate.

Mp.> 295 °C (decomposition); IR (KBr): ν~ = 2952, 2905 (CH₂),1596 (C═C), 1467 (CH₂deformation), 1355, 1284, 1267, 1245, 1222, 1181, 1132, 1105,1091, 1037 (C—Cl), 1009, 946, 891, 851, 809, 770, 730 cm^-1; ¹H NMR (CDCl₃; 500 MHz): δ = 4.20–4.10 (m, 8H; H-4, -5, -4", -5"), 2.78–2.62 (m, 4H; H-2', -5', 10', -13'), 2.20–2.00 (m, 4H; H-3', -4', -11', -12'), 0.95–0.75 (m, 4H; H-3', -4', -11', -12'); ¹³C NMR (CDCL₃,75.6 MHz): δ=128.5 (C-7', -8', -15', -16'), 120.5 (C-17', -18'), 77.6 (C-1', -6', 9', -14'), 67.7* (C-4, -4"), 66.5* (C-5, -5"), 51.8(C-2', -5', -10', 13'), 21.9 (C-3', -4', -11', -12'); EA: calc. C (41.81) H (3.19); found C: 41.83, H: 3.16 (calc.).