Di-tert-butyl cyclo­hex-2-ene-1,4-diyl dicarbonate

Syed Nawazish Ali; Mitchell A Winnik; Sabira Begum; Alan J Lough

doi:10.1107/S1600536809040343

. 2009 Oct 10;65(Pt 11):o2690. doi: 10.1107/S1600536809040343

Di-tert-butyl cyclohex-2-ene-1,4-diyl dicarbonate

Syed Nawazish Ali ^a,^*, Mitchell A Winnik ^b, Sabira Begum ^a, Alan J Lough ^b

PMCID: PMC2971395 PMID: 21578295

Abstract

In the title molecule, C₁₆H₂₆O₆, the central cyclohexene ring is in a half-chair conformation. The carbonyl groups are in a trans arrangement with respect to each other and the dihedral angle between the mean planes of the carbonate groups is 10.8 (2)°.

Related literature

For synthetic applications of the title compound, see: Ali, Ghafouri et al. (2008 ▶). For a related structures, see: Ali, Begum et al. (2008 ▶); Rademeyer et al. (2003 ▶).

Experimental

Crystal data

C₁₆H₂₆O₆
M _r = 314.37
Monoclinic,
a = 12.6548 (11) Å
b = 5.8862 (6) Å
c = 23.126 (2) Å
β = 103.147 (5)°
V = 1677.5 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 150 K
0.10 × 0.09 × 0.02 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SORTAV; Blessing 1995 ▶) T _min = 0.865, T _max = 1.00
9313 measured reflections
2893 independent reflections
1407 reflections with I > 2σ(I)
R _int = 0.101

Refinement

R[F ² > 2σ(F ²)] = 0.068
wR(F ²) = 0.191
S = 1.00
2893 reflections
205 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.26 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 datablocks global, I. DOI: 10.1107/S1600536809040343/ez2186sup1.cif

e-65-o2690-sup1.cif^{(17.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809040343/ez2186Isup2.hkl

e-65-o2690-Isup2.hkl^{(142KB, hkl)}

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

Acknowledgments

The authors acknowledge funding from the Higher Education Commission (HEC), Pakistan, Materials and Manufacturing Ontario (MMO), Canada, NSERC Canada and the University of Toronto.

supplementary crystallographic information

Comment

The title compound (I), is a new synthetic precursor of trans-cyclohex-2-ene-1,4-diol which has been synthesized for plasticizing purposes in order to break the crystallinity of a number of polyformals, and polycarbonates (Ali, Ghafouri et al., 2008). The molecular structure of (I) is shown in Fig. 1. Unlike the crystal structure of trans-Cyclohex-2-ene-1,4-diyl bis(4-nitrophenyl) dicarbonate (Ali, Begum et al., 2008) the central cyclohexene ring is completely ordered.

Experimental

A reaction mixture containing trans-cyclohex-2-ene-1,4-diol (0.59 g, 5.18 mmol), di-tert-butyldicarbonate (2.26 g, 10.36 mmol) and N,N-dimethylaminopyridine (DMAP) (0.80 g, 6.57 mmol) was stirred in dry dichloromethane (80 ml) at room temperature in a 250 ml round-bottom flask (see Fig. 2). After 4 h, it was transferred to a separatory funnel (250 ml) and washed with CH₃COOH (30 ml x 3, 0.1 M) to remove the excess of DMAP. The lower organic phase was removed and the aqueous phase was washed with dichloromethane (30 ml x 2). All the dichloromethane solutions were combined, washed with deionized water (30 ml x 3), and dried over anhydrous MgSO₄. After filtration, the solvent was removed by rotary evaporator. The resulting oily product was dried in vacuum oven at room temperature to obtain di-tert-butyl-cyclohex-2-ene-1,4-diyl dicarbonate (I, 1.14 g, 69.5%). The product was then recrystallized from a mixture of CHCl₃: MeOH (1:1) to afford needle-shaped crystals by slow evaporation of the solvent at room temperature. In addition to the X-ray structure determination, the structure was also confirmed by comparing the ¹H and ¹³C NMR data with a related t-Boc protected compound (Rademeyer et al., 2003). ¹H NMR (CDCl₃, p.p.m., relative to TMS, 400 MHz): 5.98 (2H, br.s, CH=CH), 5.16 (2H, m, CH—O), 2.08 (2H, m, CH₂—CH₂), 1.80 (2H, m, CH₂—CH₂), 1.48 (18H, s, CH₃); ¹³C NMR (CDCl₃, p.p.m., relative to TMS, 100 MHz): 168.4 (C=O), 129.1 (CH=CH), 71.4 (2H, CH—O), 66.3 (C(CH₃)₃O), 25.2 (CH₂), 28.0 (CH₃)