(1S,2S,4R)-7-tert-But­oxy­bicyclo­[2.2.1]hept-5-en-2-yl (2S)-2-(6-meth­oxy­naphthalen-2-yl)propano­ate

Alan J Lough; David A Petrone; William Tam

doi:10.1107/S1600536811024238

. 2011 Jun 30;67(Pt 7):o1848. doi: 10.1107/S1600536811024238

(1S,2S,4R)-7-tert-Butoxybicyclo[2.2.1]hept-5-en-2-yl (2S)-2-(6-methoxynaphthalen-2-yl)propanoate

Alan J Lough ^a,^*, David A Petrone ^b, William Tam ^b

PMCID: PMC3151886 PMID: 21837213

Abstract

In the title molecule, C₂₅H₃₀O₄, the napthalene ring system is slightly bowed, with a dihedral angle of 4.37 (13)° between the two benzene rings.

Related literature

For the synthesis of anti-2,7-disubstituted norbornadienes from racemic 7-tert-butoxy-bicyclo[2.2.1]hepta-5-en-2-ol, see: Tsui et al. (2009 ▶).

Experimental

Crystal data

C₂₅H₃₀O₄
M _r = 394.49
Monoclinic,
a = 11.8328 (11) Å
b = 6.0084 (4) Å
c = 15.2205 (15) Å
β = 96.705 (4)°
V = 1074.72 (16) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 150 K
0.50 × 0.20 × 0.12 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T _min = 0.480, T _max = 0.990
8333 measured reflections
2649 independent reflections
2023 reflections with I > 2σ(I)
R _int = 0.071

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.122
S = 1.05
2649 reflections
267 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Data collection: COLLECT (Nonius, 2002 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXTL (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811024238/pk2333sup1.cif

e-67-o1848-sup1.cif^{(19.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811024238/pk2333Isup2.hkl

e-67-o1848-Isup2.hkl^{(130.1KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811024238/pk2333Isup3.cml

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

Acknowledgments

The authors wish to acknowledge NSERC Canada and the University of Toronto for funding.

supplementary crystallographic information

Comment

Recently, we have investigated the synthesis of anti-2,7-disubstituted norbornadienes from racemic 7-tert-butoxy-bicyclo[2.2.1]hepta-5-en-2-ol (±) (I) (Tsui et al., 2009). In order to synthesize a chiral anti-2,7-disubstituted norbornadiene, we have studied the resolution of the racemic mixture of 7-tert-butoxy-bicyclo[2.2.1]hepta-5-en-2-ol (±) (I) through the use of α-chiral carboxylic acids as resolving agents. We found that when (S)-(+)-6-methoxy-α-methyl-2-naphthaleneacetic acid (II) (See Fig. 2) is used as the resolving agent, the diastereomeric mixture of (III) and (IV) is obtained. This mixture has been resolved using fractional crystallization which afforded diastereomer (IV) with dr > 99:1. The absolute position of the ester on the bicyclic framework has been elucidated by this single-crystal x-ray analysis.

Experimental

7-tert-butoxy-bicyclo[2.2.1]hepta-5-en-2-ol (±)-I (1.2 g, 6.4 mmol), (S)-(+)-6-methoxy-a-methyl-2-napthaleneacetic acid (II) (1.63 g, 7.08 mmol), DCC (1.58 g, 7.68 mmol), and DMAP (0.156 g, 1.28 mmol) were weighted into a dry round bottom flask and purged with nitrogen. Dried CH₂Cl₂ (64 ml) was added through a vented septum to dissolve all solids forming a 0.1 M solution with respect to (±)-I. The reaction vessel was sealed and its contents were stirred at room temperature for 21 h while monitoring the reaction progression by TLC. The crude product was purified using flash column chromatography (EtOAc:hexanes = 30:70) to provide diastereomers (III) and (IV) in equal ratio as an off white semi-solid (2.33 g, 5.9 mmol, 92%). Fractional crystallization with MeOH was used to separate these species and to grow suitable crystals of (IV).