3,9-Di-tert-butyl-2,4,8,10-tetra­oxaspiro­[5.5]undeca­ne

Abstract

The title compound, C₁₅H₂₈O₄, was prepared by the condensation of pivalaldehyde with penta­erythritol. In the crystal, the two halves of the mol­ecule are related by a crystallographic twofold rotation axis passing through the central spiro-C atom. The two non-planar six-membered heterocycles both adopt chair conformations with the two tert-butyl groups both located in the equatorial positions.

Related literature

For general background to spiranes, see: Cismaş et al. (2005 ▶); Mihiş et al. (2008 ▶); Sun et al. (2010 ▶).

Experimental

Crystal data

• C₁₅H₂₈O₄

• M _r = 272.37

• Monoclinic,

• a = 26.726 (4) Å

• b = 5.7894 (8) Å

• c = 11.2635 (15) Å

• β = 113.846 (4)°

• V = 1594.0 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 0.08 mm⁻¹

• T = 295 K

• 0.35 × 0.32 × 0.15 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.972, T _max = 0.988

• 4400 measured reflections

• 1513 independent reflections

• 1347 reflections with I > 2σ(I)

• R _int = 0.019

Refinement

• R[F ² > 2σ(F ²)] = 0.042

• wR(F ²) = 0.145

• S = 1.03

• 1513 reflections

• 90 parameters

• H-atom parameters constrained

• Δρ_max = 0.21 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

Data collection: APEX2 (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

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

supplementary crystallographic information

Comment

Owing to the characteristic axial and helical chirality, the stereochemistry of spiranes with six-membered rings has been extensively studied (Cismaş et al., 2005). In the past three decades, most of these investigations were carried out with spiranes containing 1,3-dioxane units (Mihiş et al., 2008; Sun et al., 2010). We herein present the structure of 3,9-di(tert-butyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (Fig. 1).

In the title compound, a 2-fold rotation axis passes through the central spiro-C atom (C1). The two non-planar sixmembered heterocycle [(O1/O2/C1–C4) and (O1A/O2A/C1/C2A–C4A)] both adopt chair conformations. The two tert-butyl groups locate at the equatorial position of C3 and C3A in the two six-member O-heterocycles, respectively, which give the title molecule with minimum conformational energy.

Experimental

To a solution of pivaldehyde (7.3 mmol,0.63 g) and pentaerythritol (4 mmol, 0.54 g) in toluene (30 ml), phosphotungstic acid (30 mg) was added as catalyst. The mixtures were refluxed for 6 h to complete the reaction. After reaction, the solvent was evaporated under vacuum and the resulting solid was washed with 5% sodium bicarbonate (20 ml) and 50% ethanol (20 ml). The pure product recrystallized from ethanol to afford a white solid (65% yield, m.p. 451–452 K). Single crystals suitable for X-ray diffraction were also obtained by evaporation of an ethanol solution.

Refinement

All the H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.96–0.98 Å, and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C_methyl).

Figures

Fig. 1.

The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. [symmetry code: -x, y, -z + 1/2].

Crystal data

C15H28O4	F(000) = 600
Mr = 272.37	Dx = 1.135 Mg m−3
Monoclinic, C2/c	Melting point = 451–452 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 26.726 (4) Å	Cell parameters from 3133 reflections
b = 5.7894 (8) Å	θ = 3.1–25.8°
c = 11.2635 (15) Å	µ = 0.08 mm−1
β = 113.846 (4)°	T = 295 K
V = 1594.0 (4) Å3	Block, colorless
Z = 4	0.35 × 0.32 × 0.15 mm

Data collection

Bruker APEXII CCD diffractometer	1513 independent reflections
Radiation source: fine-focus sealed tube	1347 reflections with I > 2σ(I)
graphite	Rint = 0.019
φ and ω scans	θmax = 25.8°, θmin = 3.3°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −26→32
Tmin = 0.972, Tmax = 0.988	k = −6→7
4400 measured reflections	l = −13→13

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.145	H-atom parameters constrained
S = 1.03	w = 1/[σ2(Fo2) + (0.1P)2 + 0.4P] where P = (Fo2 + 2Fc2)/3
1513 reflections	(Δ/σ)max < 0.001
90 parameters	Δρmax = 0.21 e Å−3
0 restraints	Δρmin = −0.25 e Å−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.0000	0.5543 (3)	0.2500	0.0352 (4)
C2	0.03372 (5)	0.4010 (2)	0.36479 (11)	0.0457 (4)
H2A	0.0094	0.3201	0.3953	0.055*
H2B	0.0531	0.2865	0.3366	0.055*
C3	0.10728 (4)	0.66075 (19)	0.42765 (10)	0.0374 (3)
H3	0.1261	0.5544	0.3918	0.045*
C4	0.03957 (4)	0.7056 (2)	0.21734 (10)	0.0387 (3)
H4A	0.0598	0.6105	0.1811	0.046*
H4B	0.0191	0.8192	0.1527	0.046*
C5	0.14972 (5)	0.7871 (2)	0.54331 (11)	0.0433 (3)
C6	0.12174 (6)	0.9403 (3)	0.60883 (13)	0.0582 (4)
H6A	0.0987	1.0505	0.5473	0.087*
H6B	0.1490	1.0204	0.6805	0.087*
H6C	0.1000	0.8462	0.6398	0.087*
C7	0.18565 (6)	0.6080 (3)	0.64011 (15)	0.0683 (5)
H7A	0.1634	0.5132	0.6692	0.102*
H7B	0.2128	0.6855	0.7131	0.102*
H7C	0.2034	0.5130	0.5988	0.102*
C8	0.18477 (6)	0.9364 (3)	0.49431 (15)	0.0643 (4)
H8A	0.1981	0.8436	0.4427	0.096*
H8B	0.2152	0.9985	0.5670	0.096*
H8C	0.1630	1.0607	0.4426	0.096*
O1	0.07228 (3)	0.53230 (14)	0.46900 (7)	0.0424 (3)
O2	0.07695 (3)	0.82062 (13)	0.33090 (7)	0.0382 (3)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
C1	0.0386 (8)	0.0345 (8)	0.0284 (8)	0.000	0.0094 (6)	0.000
C2	0.0484 (7)	0.0370 (6)	0.0406 (7)	−0.0019 (5)	0.0065 (6)	0.0047 (5)
C3	0.0360 (6)	0.0408 (6)	0.0326 (6)	0.0058 (4)	0.0111 (5)	0.0006 (4)
C4	0.0391 (6)	0.0486 (7)	0.0266 (5)	−0.0005 (5)	0.0114 (5)	−0.0003 (4)
C5	0.0410 (6)	0.0457 (7)	0.0337 (6)	0.0034 (5)	0.0052 (5)	−0.0004 (5)
C6	0.0714 (9)	0.0581 (8)	0.0399 (7)	0.0047 (7)	0.0173 (6)	−0.0101 (6)
C7	0.0557 (8)	0.0646 (9)	0.0557 (8)	0.0097 (7)	−0.0074 (7)	0.0053 (7)
C8	0.0473 (7)	0.0774 (11)	0.0579 (9)	−0.0140 (7)	0.0107 (6)	−0.0029 (7)
O1	0.0457 (5)	0.0433 (5)	0.0310 (5)	−0.0019 (3)	0.0081 (4)	0.0060 (3)
O2	0.0382 (5)	0.0424 (5)	0.0296 (5)	−0.0031 (3)	0.0090 (4)	0.0028 (3)

Geometric parameters (Å, °)

C1—C2i	1.5261 (14)	C4—H4B	0.9700
C1—C2	1.5261 (14)	C5—C6	1.5288 (18)
C1—C4i	1.5281 (14)	C5—C7	1.5293 (17)
C1—C4	1.5282 (14)	C5—C8	1.5322 (19)
C2—O1	1.4281 (14)	C6—H6A	0.9600
C2—H2A	0.9700	C6—H6B	0.9600
C2—H2B	0.9700	C6—H6C	0.9600
C3—O2	1.4096 (12)	C7—H7A	0.9600
C3—O1	1.4132 (13)	C7—H7B	0.9600
C3—C5	1.5244 (15)	C7—H7C	0.9600
C3—H3	0.9800	C8—H8A	0.9600
C4—O2	1.4299 (13)	C8—H8B	0.9600
C4—H4A	0.9700	C8—H8C	0.9600
C2i—C1—C2	108.90 (12)	C3—C5—C7	108.66 (10)
C2i—C1—C4i	107.94 (6)	C6—C5—C7	109.75 (11)
C2—C1—C4i	111.00 (7)	C3—C5—C8	108.36 (10)
C2i—C1—C4	111.00 (7)	C6—C5—C8	109.63 (11)
C2—C1—C4	107.94 (6)	C7—C5—C8	109.89 (11)
C4i—C1—C4	110.06 (13)	C5—C6—H6A	109.5
O1—C2—C1	111.69 (9)	C5—C6—H6B	109.5
O1—C2—H2A	109.3	H6A—C6—H6B	109.5
C1—C2—H2A	109.3	C5—C6—H6C	109.5
O1—C2—H2B	109.3	H6A—C6—H6C	109.5
C1—C2—H2B	109.3	H6B—C6—H6C	109.5
H2A—C2—H2B	107.9	C5—C7—H7A	109.5
O2—C3—O1	110.49 (8)	C5—C7—H7B	109.5
O2—C3—C5	110.02 (9)	H7A—C7—H7B	109.5
O1—C3—C5	109.50 (8)	C5—C7—H7C	109.5
O2—C3—H3	108.9	H7A—C7—H7C	109.5
O1—C3—H3	108.9	H7B—C7—H7C	109.5
C5—C3—H3	108.9	C5—C8—H8A	109.5
O2—C4—C1	110.67 (7)	C5—C8—H8B	109.5
O2—C4—H4A	109.5	H8A—C8—H8B	109.5
C1—C4—H4A	109.5	C5—C8—H8C	109.5
O2—C4—H4B	109.5	H8A—C8—H8C	109.5
C1—C4—H4B	109.5	H8B—C8—H8C	109.5
H4A—C4—H4B	108.1	C3—O1—C2	111.29 (8)
C3—C5—C6	110.53 (10)	C3—O2—C4	111.17 (8)
C2i—C1—C2—O1	171.24 (12)	O1—C3—C5—C7	64.11 (12)
C4i—C1—C2—O1	−70.06 (12)	O2—C3—C5—C8	−54.91 (12)
C4—C1—C2—O1	50.64 (12)	O1—C3—C5—C8	−176.52 (10)
C2i—C1—C4—O2	−170.67 (8)	O2—C3—O1—C2	61.88 (11)
C2—C1—C4—O2	−51.39 (12)	C5—C3—O1—C2	−176.78 (9)
C4i—C1—C4—O2	69.89 (7)	C1—C2—O1—C3	−56.61 (11)
O2—C3—C5—C6	65.24 (12)	O1—C3—O2—C4	−63.27 (10)
O1—C3—C5—C6	−56.37 (13)	C5—C3—O2—C4	175.71 (8)
O2—C3—C5—C7	−174.28 (10)	C1—C4—O2—C3	58.78 (11)

Symmetry codes: (i) −x, y, −z+1/2.