4,4-Di­methyl-3,5,8,10-tetraoxatri­cyclo­[5.2.1.0^2,6]­decane

The title compound, C₈H₁₂O₄, is formed as a by-product in the preparation of the protected sugar 2,3-O-iso­propyl­idene-β-D-ribose under acid-catalysed conditions (H₂SO₄/acetone) from D-ribose [Fleetwood & Hughes (1999). Carbohydr. Res. 317, 204–209]. The absolute configuration was assigned on the basis of the known D-ribose configuration.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.033
• wR factor = 0.069
• Data-to-parameter ratio = 6.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           25.00
         From the CIF: _reflns_number_total                771
         Count of symmetry unique reflns          775
         Completeness (_total/calc)             99.48%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.

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S1. Comment

NO COMMENT

S2. Experimental

Compound (I) is formed as a by-product in the preparation of the protected sugar (II) from D-ribose under acid-catalyzed conditions (H₂SO₄/acetone). Full details of the synthesis are given in Fleetwood & Hughes (1999).

S3. Refinement

As no elements heavier than Si were present in the title compound, the Flack (1983) parameter was meaningless and Friedel pairs were merged. All H atoms were placed geometrically and included in the refinement in riding-motion approximation, with U_iso equal to 1.2U_eq of the corresponding carrier atom (1.5U_eq for methyl H atoms).

Computing details

Data collection: COLLECT (Hooft, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997) and COLLECT (Hooft, 1998); data reduction: DENZO (Otwinowski & Minor, 1997), COLLECT and maXus (Mackay et al., 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: CAMERON (Watkin et al., 1993); software used to prepare material for publication: WinGX (Farrugia, 1998).

Figures

Fig. 1. Displacement ellipsoid plot with displacement ellipsoids drawn at the 30% probability level.

4,4-Dimethyl-3,5,8,10-tetraoxatricyclo[5.2.1.0^2,6]decane

Crystal data

C8H12O4	F(000) = 184
Mr = 172.18	Dx = 1.428 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
a = 8.1183 (7) Å	Cell parameters from 3809 reflections
b = 5.9280 (5) Å	θ = 4.2–25.0°
c = 9.0398 (7) Å	µ = 0.12 mm^−1
β = 113.000 (7)°	T = 120 K
V = 400.46 (6) Å^3	Block, colourless
Z = 2	0.20 × 0.10 × 0.10 mm

Data collection

Bruker–Nonius KappaCCD area-detector diffractometer	771 independent reflections
Radiation source: Bruker Nonius FR591 Rotating anode	620 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.069
Detector resolution: 9.091 pixels mm^1 pixels mm^-1	θmax = 25.0°, θmin = 4.2°
ϕ and ω scans to fill the asymmetric unit	h = −9→9
Absorption correction: multi-scan (SORTAV; Blessing, 1997)	k = −6→7
Tmin = 0.977, Tmax = 0.989	l = −10→10
3809 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.033	w = 1/[σ^2(Fo^2) + (0.0343P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.069	(Δ/σ)max = 0.001
S = 1.03	Δρmax = 0.16 e Å^−3
771 reflections	Δρmin = −0.17 e Å^−3
112 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.051 (9)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983)
Secondary atom site location: difference Fourier map

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	0.9472 (4)	0.3881 (5)	0.8485 (3)	0.0211 (7)
H1	0.9986	0.4416	0.9625	0.025*
C2	0.7454 (4)	0.3654 (5)	0.7754 (3)	0.0211 (7)
H2	0.6829	0.5133	0.7403	0.025*
O3	0.6810 (2)	0.2413 (3)	0.8764 (2)	0.0225 (5)
C4	0.5576 (4)	0.0780 (5)	0.7770 (3)	0.0198 (7)
O5	0.6405 (2)	0.0061 (3)	0.6699 (2)	0.0198 (5)
C6	0.7175 (4)	0.2033 (5)	0.6332 (3)	0.0192 (7)
H6	0.6421	0.2701	0.5265	0.023*
C7	0.9112 (4)	0.1654 (5)	0.6539 (3)	0.0196 (7)
H7	0.9295	0.0263	0.5996	0.024*
O8	0.9668 (2)	0.3694 (3)	0.6012 (2)	0.0226 (5)
C9	1.0001 (4)	0.5267 (6)	0.7325 (3)	0.0263 (7)
H9B	0.9251	0.6636	0.6967	0.032*
H9A	1.1277	0.5713	0.7814	0.032*
O10	1.0063 (2)	0.1653 (3)	0.8225 (2)	0.0203 (5)
C11	0.3781 (4)	0.1855 (6)	0.6853 (3)	0.0251 (7)
H11A	0.3925	0.3110	0.6208	0.038*
H11B	0.3285	0.2421	0.7611	0.038*
H11C	0.2966	0.0732	0.6144	0.038*
C12	0.5486 (4)	−0.1174 (5)	0.8775 (3)	0.0252 (7)
H12A	0.6698	−0.1733	0.9394	0.038*
H12B	0.4767	−0.2379	0.8078	0.038*
H12C	0.4934	−0.0693	0.9513	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0221 (16)	0.0209 (18)	0.0209 (15)	−0.0011 (14)	0.0088 (12)	−0.0061 (13)
C2	0.0220 (15)	0.0201 (17)	0.0243 (15)	0.0000 (14)	0.0123 (12)	−0.0006 (13)
O3	0.0213 (11)	0.0294 (14)	0.0188 (10)	−0.0035 (10)	0.0098 (8)	−0.0053 (9)
C4	0.0212 (16)	0.0239 (19)	0.0163 (14)	−0.0005 (13)	0.0096 (12)	−0.0049 (12)
O5	0.0234 (11)	0.0211 (12)	0.0191 (10)	−0.0027 (9)	0.0131 (8)	−0.0026 (9)
C6	0.0220 (16)	0.0177 (19)	0.0191 (14)	−0.0026 (14)	0.0091 (11)	0.0017 (12)
C7	0.0221 (17)	0.0207 (17)	0.0198 (14)	−0.0044 (14)	0.0121 (11)	0.0017 (13)
O8	0.0266 (11)	0.0203 (12)	0.0228 (11)	−0.0007 (10)	0.0117 (8)	0.0028 (9)
C9	0.0282 (17)	0.0197 (18)	0.0337 (17)	−0.0042 (14)	0.0152 (13)	−0.0024 (14)
O10	0.0206 (11)	0.0213 (12)	0.0189 (9)	0.0024 (9)	0.0075 (8)	0.0003 (9)
C11	0.0189 (16)	0.0290 (19)	0.0283 (15)	0.0000 (15)	0.0102 (12)	−0.0026 (14)
C12	0.0267 (17)	0.0276 (18)	0.0254 (15)	−0.0007 (15)	0.0147 (12)	0.0000 (14)

Geometric parameters (Å, º)

C1—O10	1.456 (4)	C6—H6	1.0000
C1—C2	1.514 (4)	C7—O10	1.414 (3)
C1—C9	1.520 (4)	C7—O8	1.436 (3)
C1—H1	1.0000	C7—H7	1.0000
C2—O3	1.422 (3)	O8—C9	1.450 (3)
C2—C6	1.549 (4)	C9—H9B	0.9900
C2—H2	1.0000	C9—H9A	0.9900
O3—C4	1.430 (3)	C11—H11A	0.9800
C4—O5	1.443 (3)	C11—H11B	0.9800
C4—C12	1.491 (4)	C11—H11C	0.9800
C4—C11	1.508 (4)	C12—H12A	0.9800
O5—C6	1.425 (3)	C12—H12B	0.9800
C6—C7	1.526 (4)	C12—H12C	0.9800
O10—C1—C2	102.6 (2)	O10—C7—O8	104.4 (2)
O10—C1—C9	100.3 (2)	O10—C7—C6	103.60 (19)
C2—C1—C9	107.2 (2)	O8—C7—C6	106.1 (2)
O10—C1—H1	115.0	O10—C7—H7	113.9
C2—C1—H1	115.0	O8—C7—H7	113.9
C9—C1—H1	115.0	C6—C7—H7	113.9
O3—C2—C1	111.8 (2)	C7—O8—C9	104.61 (18)
O3—C2—C6	103.9 (2)	O8—C9—C1	101.8 (2)
C1—C2—C6	101.5 (2)	O8—C9—H9B	111.4
O3—C2—H2	112.9	C1—C9—H9B	111.4
C1—C2—H2	112.9	O8—C9—H9A	111.4
C6—C2—H2	112.9	C1—C9—H9A	111.4
C2—O3—C4	106.84 (19)	H9B—C9—H9A	109.3
O3—C4—O5	103.1 (2)	C7—O10—C1	95.6 (2)
O3—C4—C12	109.4 (2)	C4—C11—H11A	109.5
O5—C4—C12	109.0 (2)	C4—C11—H11B	109.5
O3—C4—C11	110.4 (2)	H11A—C11—H11B	109.5
O5—C4—C11	111.1 (2)	C4—C11—H11C	109.5
C12—C4—C11	113.3 (2)	H11A—C11—H11C	109.5
C6—O5—C4	106.0 (2)	H11B—C11—H11C	109.5
O5—C6—C7	112.1 (2)	C4—C12—H12A	109.5
O5—C6—C2	104.5 (2)	C4—C12—H12B	109.5
C7—C6—C2	100.4 (2)	H12A—C12—H12B	109.5
O5—C6—H6	113.0	C4—C12—H12C	109.5
C7—C6—H6	113.0	H12A—C12—H12C	109.5
C2—C6—H6	113.0	H12B—C12—H12C	109.5