Bicyclo­[2.2.1]hept-7-yl p-bromo­benzoate

Barry A Lloyd; Atta M Arif

doi:10.1107/S1600536812041268

. 2012 Oct 6;68(Pt 11):o3086–o3087. doi: 10.1107/S1600536812041268

Bicyclo[2.2.1]hept-7-yl p-bromobenzoate

Barry A Lloyd ^a,^*, Atta M Arif ^b

PMCID: PMC3515191 PMID: 23284418

Abstract

The title compound, C₁₄H₁₅BrO₂, contains a sterically unencumbered norbornyl group. The dihedral angle between the plane of the carboxylate group and the mean plane of the adjacent benzene ring is 5.3 (2)°. The dihedral angle between the plane of the carboxylate group and the norbornyl methano C—O bond is 4.5 (1)°, the methano C atom deviating by 0.141 (2) Å from this plane. In the crystal, molecules pack as pairs of enantiomers, with a distance of 3.747 (1) Å between the centroids of nearest parallel benzene rings.

Related literature

For calculated and experimental norbornane and related structures, see: Allinger et al. (1989 ▶); Pfund et al. (1980 ▶). For related polycyclic p-bromobenzoate structures, see: Lloyd & Arif (2012 ▶); Lloyd et al. (1995 ▶, 2000 ▶). For a high resolution low temperature powder synchrotron X-ray diffraction structure of norbornane, see: Fitch & Jobic (1993 ▶). For some norbornyl bond lengths and angles, see: Watson et al. (1992 ▶). For possible C—O bond-length correlation to reactivity in a 7-norbornenyl benzoate, see: Jones et al. (1992 ▶).

Experimental

Crystal data

C₁₄H₁₅BrO₂
M _r = 295.17
Monoclinic,
a = 11.7401 (2) Å
b = 6.3767 (1) Å
c = 17.7462 (3) Å
β = 109.584 (1)°
V = 1251.68 (4) Å³
Z = 4
Mo Kα radiation
μ = 3.27 mm⁻¹
T = 150 K
0.30 × 0.25 × 0.18 mm

Data collection

Nonius KappaCCD Diffractometer
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997 ▶) T _min = 0.440, T _max = 0.591
5495 measured reflections
2882 independent reflections
2469 reflections with I > 2σ(I)
R _int = 0.015

Refinement

R[F ² > 2σ(F ²)] = 0.022
wR(F ²) = 0.055
S = 1.03
2882 reflections
215 parameters
All H-atom parameters refined
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: WinGX (Farrugia, 2012 ▶), ORTEP-3 for Windows (Farrugia, 2012 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: Mercury (Macrae et al., 2008 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Click here for additional data file.^{(17.8KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812041268/fj2598sup1.cif

e-68-o3086-sup1.cif^{(17.8KB, cif)}

Click here for additional data file.^{(141.5KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812041268/fj2598Isup2.hkl

e-68-o3086-Isup2.hkl^{(141.5KB, hkl)}

Click here for additional data file.^{(1.6KB, mol)}

Supplementary material file. DOI: 10.1107/S1600536812041268/fj2598Isup3.mol

Click here for additional data file.^{(4.7KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812041268/fj2598Isup4.cml

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

Acknowledgments

We thank the Weber State Chemistry Department for supporting this work, the University of Utah Chemistry Department X-ray crystallographic facility, and the late Professor Evan L. Allred who began this work.

supplementary crystallographic information

Comment

Many norbornyl structures have been previously determined, but precise bond lengths and angles are derivative dependent (Watson et al., 1992). The Cambridge Crystallographic Database contains only five 7-norbornyl benzoate structures, but these are complicated by additional substituents and their associated steric interactions (for example, see Pfund et al., 1980). An ORTEP-3 drawing (Farrugia, 2012) of title compound structure 1 is shown in Fig. 1, and a cell packing diagram is shown in Fig. 2. Structure 1 norbornyl group bond lengths and bond angles agree with reported values, but their precision is about ten times better than geometry averaged values (Watson et al., 1992). Structure 1 was determined so that bond length, bond angle, least-squares plane, and nonbonding contact comparisons could be made with other related p-bromobenzoate structures (Lloyd & Arif, 2012, Lloyd et al., 2000 and Lloyd et al., 1995).

No nonhydrogen atom intermolecular contacts exist shorter than van der Waals radii sums, the smallest being O1ⁱ···C13ⁱⁱ at 3.257 (2) Å [symmetry code: (ii) x, -1 + y, z]. Least squares planes are defined as C1—C7—C4 (plane 1), C1—C2—C3—C4 (plane 2), and C1—C6—C5—C4 (plane 3). Interplanar 1:2, 1:3, and 1:4 angles are: 121.2 (1)°, 125.5 (1)°, and 113.3 (1)°, respectively. Angle 1:2 is 1.4° larger than the corresponding 296 K structure 2 (Fig. 3) angle (Lloyd et al., 1995), but smaller than corresponding angles of our other seven norbornenyl structures. Structure 1 angle 1: 3 is larger than analogous angles in all eight norbornenyl structures, and angle 2:3 is smaller for all except structure 3. Smaller 1:2 and larger 1:3 angles in structure 1 are likely a consequence of a longer C2—C3 norbornyl single bond (versus a shorter norbornenyl C2=C3 double bond) which bends C7 toward plane 2. The slightly larger structure 1 2:3 angle versus3 might result from intramolecular H3B···H5A and H2B···H6A contacts, 2.35 (3) and 2.40 (3) Å, respectively (Lloyd & Arif, 2012). Reactant structural features (such as C7—O2 bond length) that might portend the large norbornenyl: norbornyl solvolytic reactivity ratio are not obvious, and the late transition state idea (Jones et al., 1992) is supported.

Experimental

7-Norbornyl p-bromobenzoate (title compound 1) was made from commercial bicyclo[2.2.1]heptan-7-ol (7-norborneol, Alfa Products). Under a dry nitrogen atmosphere, 1.06 g freshly distilled (about 300 K, 7 Pa) p-bromobenzoyl chloride, 15 ml reagent grade dichloromethane, 0.802 g dry, freshly distilled (from CaH₂ under N₂) pyridine, and 0.540 g of sublimed (373 K, 7 Pa) 7-norborneol were combined and the mixture was refluxed for 15 min, then stirred for 2 d at 296 K. The reaction mixture was poured into 10 ml of 5% HCl solution, and layers were separated. The dichloromethane layer was washed twice more with 5% HCl solution, the dichloromethane was evaporated, and the residue was dissolved in about 3 ml of ether. The mixture was chromatographed on Florisil (petroleum ether, then ether). Recovered 1.22 g of 1, 85.3% yield, mp 350–351 K after two recrystallizations from petroleum ether/ether: ¹H NMR (CDCl₃, 90 MHz) δ 1.10–1.57 (4 H, m), 1.57–2.09 (4 H, m), 2.31 (2 H, m), 4.99 (1 H, s), 7.57 (2 H, d), 7.88 (2 H, d). Crystals were regrown slowly by dissolving 1.0 g of 1 in 5 ml of anhydrous ether in a 30 ml beaker. The beaker was placed inside a desiccator along with a 20 ml beaker containing 15 ml of petroleum ether (bp 303–333 K), and the desiccator was placed inside a freezer at 253 K. A one-hole rubber stopper was placed in the desiccator neck with glass wool inserted into the hole, allowing for slow evaporation. Crystals began forming after 3 d and they were filtered out after 5 d. One of these crystals was selected for X-ray analysis.