2,3:4,6-Di-O-isopropyl­idene-α-L-sorbofuran­ose and 2,3-O-isopropyl­idene-α-L-sorbofuran­ose

In the title compounds, C₁₂H₂₀O₆, (I), and C₉H₁₆O₆, (II), the five-membered furan­ose ring adopts a ⁴T₃ conformation and the five-membered 1,3-dioxolane ring adopts an E₃ conformation. The six-membered 1,3-dioxane ring in (I) adopts an almost ideal ^OC₃ conformation. The hydrogen-bonding patterns for these compounds differ substanti­ally: (I) features just one intra­molecular O—H...O hydrogen bond [O...O = 2.933 (3) Å], whereas (II) exhibits, apart from the corresponding intra­molecular O—H...O hydrogen bond [O...O = 2.7638 (13) Å], two inter­molecular bonds of this type [O...O = 2.7708 (13) and 2.7730 (12) Å]. This study illustrates both the similarity between the con­formations of furan­ose, 1,3-dioxolane and 1,3-di­oxane rings in analogous isopropyl­idene-substituted carbohydrate structures and the only negligible influence of the presence of a 1,3-dioxane ring on the conformations of furan­ose and 1,3-dioxolane rings. In addition, in comparison with reported analogs, replacement of the –CH₂OH group at the C1-furan­ose position by another group can considerably affect the conformation of the 1,3-dioxolane ring.

S1. Comment

The title isopropylidene derivatives of L-sorbofuranose, namely 2,3:4,6-di-O-isopropylidene-α-L-sorbofuranose, (I), and 2,3-O-isopropylidene-α-L-sorbofuranose, (II), are useful intermediates in organic synthesis. They have been used as starting materials for the stepwise synthesis of 1-deoxynojirimycin (Beaupere et al., 1989), the 6,6-difluoro analog (Szarek et al., 1997) and N-butyl-1-deoxynojirimycin (N-Bu DNJ, Zavesca) (Boucheron et al., 2005; Godin et al., 2002), known as a very efficient glycosidase inhibitors used, inter alia, as a therapeutic in the treatment for lysosomal disease. In the context of studies on the synthesis of iminosugar derivatives related to nojirimycin and mannojirimycin, we have prepared (I) from L-sorbose using acetone as isopropylidenation agent and concentrated sulfuric acid as a catalyst. Subsequent selective acid hydrolysis of the 4,6-O-isopropylidene group in (I) afforded the monoisopropylidenated compound (II).

The molecular structures of (I) and (II) are illustrated in Figs. 1 and 2 [the numbering of atoms corresponds to the numbering according to the IUPAC Nomenclature of Carbohydrates (McNaught, 1996)]. The puckering parameters (Cremer & Pople, 1975) Q = 0.250 (2)Å and ϕ = 112.(6)°, and the relevant dihedral angles (see Table 2) are indicative of the E₃ (E_O3) conformation for the O2/C2/C3/O3/C7 five-membered 1,3-dioxolane ring in (I). Considering the values for (I) of the relevant torsion angles (Table 2) and the puckering parameters Q = 0.370 (3)Å and ϕ = 127.0 (4)°, the five-membered O5/C2–C5 furanose ring adopts a ⁴T₃ (^C5T_C4) conformation, with atom C4 lying in the exo and C5 the endo direction with respect to the O5/C2/C3 reference plane. Based on the values of relevant torsion angles (Table 2) and the puckering parameters Q = 0.509 (3)Å, ϕ = 300.0 (19)° and θ = 8.7 (3)°, the O4/C4–C6/O6/C10 six-membered 1,3-dioxane ring adopts an almost ideal ^OC₃ (^O4C_C6) conformation slightly shifted to the E₅ direction. Similar for compound (II), the puckering parameters Q = 0.2810 (11)Å and ϕ = 110.4 (2)° and the relevant dihedral angles (Table 2) are indicative of the E₃ (E_O3) conformation for the O2/C2/C3/O3/C7 five-membered 1,3-dioxolane ring. Analogously, considering the values of the relevant torsion angles (Table 2) and the puckering parameters Q = 0.3958 (11)Å and ϕ = 123.07 (16)°, the five-membered O5/C2–C5 furanose ring adopts a ⁴T₃ (^C5T_C4) conformation.

To date, only a few crystal structures of this general type have been described. Among them, the most closely related structure is 2,3:4,6-di-O-isopropylidene-α-L-xylo-hex-2-ulosonic acid (2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid) [CSD (Allen, 2002) refcode DIPKGA (Takagi & Jeffrey, 1978)]. Related structures include 1-phthalimido-1-deoxy-2,3:4,6-di-O-isopropylidene-α-L-sorbofuranose (refcode PHISOR; Glass & Johnson, 1976), cis-6-(2-deoxy-3,5-O-isopropylidene-1,2-isopropylidenedioxy-β-L-xylo-furanosyl)-2,3-dimethyl-1,2,5-oxadiazinane (refcode XAKKUP; Gravestock et al., 2000) and [2R,3S,4S,5S,5(2S,3S,4R,5S)]-5-(2,3,4-trihydroxy-5-hydroxymethyl-2,3:4,5'-di-O-isopropylidene-2-tetrahydrofuranyl)-4-methyl-2-phenyltetrahydrofuran-3-carbaldehyde (refcode TEZHAI; Kollmann et al., 2007) have the exocyclic CH₂OH group replaced by a more complicated organic functionality and, finally, (2,3-O-isopropylidene-α-L-sorbofuranose)trimethylplatinum(IV) tetrafluoroborate (refcode GOZJEK; Junicke et al., 1999) is a metal–carbohydrate complex where 2,3-O-isopropylidene-α-L-sorbofuranose represents a tridentate ligand coordinated via the hydroxyl groups at C1, C4 and C6 positions to the Pt^IV centre.

A comparison of (I) and (II) with these structures shows only small differences in the conformation of furanose ring. Only TEZHAI exhibited the ⁴E (C4 furanose atom in endo direction) conformation, while the ⁴T₃ conformation was observed for the other structures. Conformational similarity can be also seen for 1,3-dioxane ring in (I) and in related structures. Thus, in (I), PHISOR, TEZHAI and DIPKGA, the ⁰C₃ conformation is slightly distorted to the E₅ direction, while a slight shift to the ⁴H₅ direction is observed for XAKKUP. Regarding the 1,3-dioxolane ring, its conformation is considerably affected by the substitution at C1 furanose position (CH₂OH versus other substituent). In this respect, the 1,3-dioxolane ring in (I), (II) and GOZJEK adopts the E₃ (O3 atom in an endo direction) conformation, while ⁴T₃ (for TEZHAI and XAKKUP), ³E (for DIPKGA) and the ⁴T₃ conformation shifted halfway to the ⁴E direction (for PHISOR) is observed.

Although the presence of a 1,3-dioxane ring fused to a furanose ring at the 4,6-positions imposes some conformational rigidity on (I), its influence on conformation of furanose (in a significant shift of E₃ → ⁴T₃) and 1,3-dioxolane ring is, as seen from comparison with (II), negligible (see Fig. 3). The most dramatic change in the conformation is apparent in the C2—C1—O1—H1 torsion angle from 8 to 127° for (I) and (II), respectively.

The hydrogen-bonding patterns are very different in both compounds. For (I), there is one strong intramolecular O—H···O hydrogen bond (Fig. 1) and some weak intermolecular C—H···O hydrogen bonds (see Table 1 for details). For (II), there are strong O—H···O hydrogen bonds, one intramolecular (denoted as a in Table 3) and two intermolecular (b and c), together with other weak intermolecular C—H···O hydrogen bonds (Table 3). On the first-level graph-set, defined by Bernstein et al. (1995) and Grell et al. (1999), string S(7) (bond a) and chains C(8) (b) and C(6) (c) were identified. On the second-level graph-set, chains C₂²(9) and C₂²(14) formed by hydrogen bonds (b and c) could be recognized. On the third-level graph set, rings R₅⁵(21) can be found (a, b and c), see Fig. 4 and Table 3.

Related literature

For related literature, see: Beaupere et al. (1989); Boucheron et al. (2005); Cremer & Pople (1975); Glass & Johnson (1976); Godin et al. (2002); Gravestock et al. (2000); Grell et al. (1999); Junicke et al. (1999); Kollmann et al. (2007); McNaught (1996); Slobodin (1947); Szarek et al. (1997); Takagi & Jeffrey (1978).

S2. Experimental

Compound (I) was prepared according to a slight modification of the procedure of Slobodin (1947) (fast neutralization under efficient cooling using NaOH instead of KHCO₃; four extractions with ethyl acetate instead of 11 extractions with CHCl₃ was deemed sufficient). Compound (II) was obtained by heating (I) in 60% acetic acid at 348 K for 40 min, followed by evaporation of the solvent under reduced pressure and crystallization of the product from a mixture of ethyl acetate and hexane. The analytical data for (I) and (II) were in accordance with those published previously (Szarek et al., 1997; Beaupere et al., 1989). Colourless single crystals of adequate quality for diffraction analysis were obtained by slow crystallization of (I) from a 2:1 (v/v) mixture of diethyl ether and n-hexane under moderate cooling in a refrigerator. Analogous crystallization using a mixture of of ethyl acetate and n-hexane (2:1 v/v) afforded suitable crystals of (II).

S3. Refinement

In the absence of significant resonant scattering, the Friedel-equivalent reflections were merged for compounds (I) and (II), and therefore the absolute configuration of the molecules in (I) and (II) were not determined by diffraction techniques. However, the absolute configuration at chiral atoms C2, C3, C4 and C5 in (I) and (II) was assigned on the basis of the known arrangement in L-sorbofuranose derivatives, because isopropylidenation at O4 and O6 does not affect the arrangements of atoms O3, O4 and O5 with respect to the furanose ring in (I) and acetonation at O2 and O3 affords preferentially the cis-2,3-O-isopropylidenated product with an α configuration at anomeric atom C2. For secondary H atoms, the C—H distance was fixed at 0.99Å and for tertiary at 1.00Å. For the methyl groups, the C—H distances (0.98Å) and C—C—H angles (109.5°) were kept fixed. The O—H distances (0.84Å) and C—C—H angles (109.5°) were fixed. Isotropic displacement parameters were constrained to U_iso(H) = 1.2U_eq(C), 1.5U_eq(C_methyl) and 1.5U_eq(O).

Computing details

For both compounds, data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003) and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A view of (I), showing the atom-numbering scheme. Displacement ellipsoids are shown at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. The intramolecular O—H···O hydrogen bond is shown as a dashed line.
	Fig. 2. A view of (II), showing the atom-numbering scheme. Displacement ellipsoids are shown at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. The intramolecular O—H···O hydrogen bond is shown as a dashed line.
	Fig. 3. A projection of (I) (red in the online version of the paper) and (II) (blue) with the furanose ring fitted as a common fragment. H atoms have been omitted for clarity.
	Fig. 4. The hydrogen bonding in (II) depicted as dashed lines. H atoms not involved in the strong hydrogen bonds have been omitted for clarity. Symmetry codes and geometric details are listed in Table 3.

(I) 2,3:4,6-di-O-isopropylidene-α-L-sorbofuranose

Crystal data

C12H20O6	F(000) = 560
Mr = 260.28	Dx = 1.261 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3977 reflections
a = 6.7203 (16) Å	θ = 2.4–25.0°
b = 9.286 (2) Å	µ = 0.10 mm^−1
c = 21.972 (5) Å	T = 153 K
V = 1371.1 (6) Å^3	Irregular block, colourless
Z = 4	0.78 × 0.48 × 0.32 mm

Data collection

Siemens SMART CCD area-detector diffractometer	1483 independent reflections
Radiation source: fine-focus sealed tube	1236 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.067
ω scans	θmax = 25.4°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −8→8
Tmin = 0.440, Tmax = 0.969	k = −11→11
15054 measured reflections	l = −26→26

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.098	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0661P)^2 + 0.1325P] where P = (Fo^2 + 2Fc^2)/3
1483 reflections	(Δ/σ)max < 0.001
168 parameters	Δρmax = 0.20 e Å^−3
0 restraints	Δρmin = −0.24 e Å^−3

Special details

Experimental. Data were collected at low temperature using a Siemens SMART CCD diffractometer equipped with a LT-2 device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 1 second per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Siemens, 1995). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 3977 reflections with I>10σ(I) after integration of all the frames data using SAINT (Siemens, 1995).

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
O1	0.9233 (3)	0.9707 (2)	0.09736 (8)	0.0394 (5)
H1	0.8191	0.9577	0.1177	0.059*
O2	0.6209 (3)	0.93796 (18)	−0.03997 (7)	0.0296 (4)
O3	0.3917 (2)	1.09678 (18)	−0.00481 (7)	0.0286 (4)
O4	0.5305 (2)	1.02849 (19)	0.15016 (8)	0.0280 (4)
O5	0.5865 (2)	0.82378 (16)	0.05348 (8)	0.0255 (4)
O6	0.4873 (3)	0.79170 (19)	0.18309 (8)	0.0352 (5)
C1	0.8789 (3)	0.9596 (3)	0.03459 (12)	0.0319 (6)
H1A	0.9457	0.8733	0.0177	0.038*
H1B	0.9321	1.0451	0.0132	0.038*
C2	0.6563 (3)	0.9487 (3)	0.02292 (11)	0.0233 (5)
C3	0.5237 (4)	1.0734 (2)	0.04474 (11)	0.0239 (5)
H3	0.6013	1.1613	0.0560	0.029*
C4	0.4079 (4)	1.0115 (3)	0.09739 (11)	0.0241 (5)
H4	0.2741	1.0573	0.1023	0.029*
C5	0.3946 (4)	0.8528 (3)	0.07970 (11)	0.0248 (5)
H5	0.2877	0.8383	0.0486	0.030*
C6	0.3612 (4)	0.7554 (3)	0.13298 (12)	0.0311 (6)
H6A	0.2204	0.7623	0.1459	0.037*
H6B	0.3871	0.6546	0.1206	0.037*
C7	0.4864 (4)	1.0487 (3)	−0.05926 (11)	0.0273 (6)
C8	0.3315 (4)	0.9848 (3)	−0.10048 (13)	0.0390 (7)
H8A	0.2681	0.9027	−0.0802	0.058*
H8B	0.3945	0.9522	−0.1383	0.058*
H8C	0.2307	1.0577	−0.1099	0.058*
C9	0.6024 (5)	1.1697 (3)	−0.08852 (14)	0.0409 (7)
H9A	0.5116	1.2484	−0.0990	0.061*
H9B	0.6674	1.1343	−0.1255	0.061*
H9C	0.7035	1.2048	−0.0600	0.061*
C10	0.4758 (4)	0.9399 (3)	0.20076 (12)	0.0332 (6)
C11	0.2711 (4)	0.9796 (4)	0.22501 (14)	0.0437 (7)
H11A	0.1729	0.9718	0.1922	0.066*
H11B	0.2735	1.0787	0.2403	0.066*
H11C	0.2350	0.9140	0.2581	0.066*
C12	0.6366 (5)	0.9590 (4)	0.24816 (12)	0.0479 (8)
H12A	0.6038	0.9018	0.2843	0.072*
H12B	0.6459	1.0609	0.2594	0.072*
H12C	0.7643	0.9267	0.2315	0.072*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0225 (9)	0.0523 (12)	0.0433 (11)	−0.0037 (9)	−0.0060 (8)	−0.0041 (10)
O2	0.0324 (9)	0.0262 (9)	0.0301 (9)	0.0052 (8)	−0.0008 (8)	−0.0054 (7)
O3	0.0271 (8)	0.0283 (9)	0.0305 (10)	0.0056 (8)	0.0001 (8)	0.0023 (7)
O4	0.0301 (9)	0.0247 (9)	0.0291 (9)	0.0005 (8)	−0.0037 (7)	−0.0027 (7)
O5	0.0220 (8)	0.0151 (8)	0.0395 (10)	0.0021 (7)	0.0014 (8)	−0.0022 (7)
O6	0.0440 (11)	0.0265 (10)	0.0351 (11)	0.0035 (9)	−0.0100 (9)	0.0017 (8)
C1	0.0210 (12)	0.0311 (14)	0.0437 (16)	−0.0014 (11)	0.0002 (11)	−0.0073 (12)
C2	0.0208 (11)	0.0192 (12)	0.0297 (13)	−0.0018 (10)	0.0012 (10)	−0.0033 (10)
C3	0.0236 (11)	0.0162 (11)	0.0319 (13)	0.0016 (10)	−0.0001 (11)	−0.0025 (10)
C4	0.0214 (11)	0.0213 (12)	0.0296 (13)	0.0047 (10)	−0.0002 (10)	−0.0021 (10)
C5	0.0205 (11)	0.0229 (12)	0.0311 (14)	−0.0005 (11)	−0.0005 (11)	−0.0016 (10)
C6	0.0321 (14)	0.0261 (14)	0.0351 (15)	−0.0026 (11)	−0.0023 (12)	0.0025 (11)
C7	0.0314 (13)	0.0206 (12)	0.0300 (14)	0.0004 (11)	0.0023 (11)	0.0026 (11)
C8	0.0433 (15)	0.0336 (16)	0.0401 (16)	−0.0048 (13)	−0.0113 (13)	0.0035 (13)
C9	0.0481 (16)	0.0294 (15)	0.0452 (17)	−0.0100 (14)	0.0088 (15)	0.0017 (13)
C10	0.0404 (15)	0.0296 (14)	0.0296 (14)	0.0030 (13)	−0.0017 (12)	−0.0008 (12)
C11	0.0462 (16)	0.0469 (19)	0.0379 (17)	0.0051 (15)	0.0076 (14)	0.0028 (14)
C12	0.058 (2)	0.0474 (19)	0.0380 (17)	0.0050 (18)	−0.0160 (15)	−0.0056 (14)

Geometric parameters (Å, º)

O1—C1	1.415 (3)	C5—C6	1.496 (3)
O1—H1	0.8400	C5—H5	1.0000
O2—C2	1.406 (3)	C6—H6A	0.9900
O2—C7	1.433 (3)	C6—H6B	0.9900
O3—C3	1.421 (3)	C7—C8	1.502 (4)
O3—C7	1.427 (3)	C7—C9	1.512 (3)
O4—C10	1.431 (3)	C8—H8A	0.9800
O4—C4	1.431 (3)	C8—H8B	0.9800
O5—C2	1.420 (3)	C8—H8C	0.9800
O5—C5	1.437 (3)	C9—H9A	0.9800
O6—C10	1.432 (3)	C9—H9B	0.9800
O6—C6	1.430 (3)	C9—H9C	0.9800
C1—C2	1.521 (3)	C10—C12	1.511 (4)
C1—H1A	0.9900	C10—C11	1.521 (4)
C1—H1B	0.9900	C11—H11A	0.9800
C2—C3	1.538 (3)	C11—H11B	0.9800
C3—C4	1.508 (3)	C11—H11C	0.9800
C3—H3	1.0000	C12—H12A	0.9800
C4—C5	1.528 (3)	C12—H12B	0.9800
C4—H4	1.0000	C12—H12C	0.9800
C1—O1—H1	109.5	O6—C6—H6B	109.3
C2—O2—C7	110.28 (18)	C5—C6—H6B	109.3
C3—O3—C7	108.44 (16)	H6A—C6—H6B	107.9
C10—O4—C4	114.73 (19)	O3—C7—O2	104.95 (18)
C2—O5—C5	109.45 (17)	O3—C7—C8	108.7 (2)
C10—O6—C6	113.8 (2)	O2—C7—C8	109.4 (2)
O1—C1—C2	112.1 (2)	O3—C7—C9	110.7 (2)
O1—C1—H1A	109.2	O2—C7—C9	109.5 (2)
C2—C1—H1A	109.2	C8—C7—C9	113.2 (2)
O1—C1—H1B	109.2	C7—C8—H8A	109.5
C2—C1—H1B	109.2	C7—C8—H8B	109.5
H1A—C1—H1B	107.9	H8A—C8—H8B	109.5
O2—C2—O5	110.57 (19)	C7—C8—H8C	109.5
O2—C2—C1	109.7 (2)	H8A—C8—H8C	109.5
O5—C2—C1	107.4 (2)	H8B—C8—H8C	109.5
O2—C2—C3	105.17 (19)	C7—C9—H9A	109.5
O5—C2—C3	106.03 (18)	C7—C9—H9B	109.5
C1—C2—C3	117.9 (2)	H9A—C9—H9B	109.5
O3—C3—C4	108.90 (19)	C7—C9—H9C	109.5
O3—C3—C2	103.76 (19)	H9A—C9—H9C	109.5
C4—C3—C2	104.56 (19)	H9B—C9—H9C	109.5
O3—C3—H3	113.0	O6—C10—O4	109.1 (2)
C4—C3—H3	113.0	O6—C10—C12	105.1 (2)
C2—C3—H3	113.0	O4—C10—C12	106.5 (2)
O4—C4—C3	106.40 (19)	O6—C10—C11	112.1 (2)
O4—C4—C5	110.24 (19)	O4—C10—C11	111.4 (2)
C3—C4—C5	101.68 (19)	C12—C10—C11	112.1 (2)
O4—C4—H4	112.6	C10—C11—H11A	109.5
C3—C4—H4	112.6	C10—C11—H11B	109.5
C5—C4—H4	112.6	H11A—C11—H11B	109.5
O5—C5—C6	109.6 (2)	C10—C11—H11C	109.5
O5—C5—C4	103.32 (19)	H11A—C11—H11C	109.5
C6—C5—C4	113.1 (2)	H11B—C11—H11C	109.5
O5—C5—H5	110.2	C10—C12—H12A	109.5
C6—C5—H5	110.2	C10—C12—H12B	109.5
C4—C5—H5	110.2	H12A—C12—H12B	109.5
O6—C6—C5	111.8 (2)	C10—C12—H12C	109.5
O6—C6—H6A	109.3	H12A—C12—H12C	109.5
C5—C6—H6A	109.3	H12B—C12—H12C	109.5
C7—O2—C2—O5	116.75 (19)	C2—C3—C4—C5	−29.7 (2)
C7—O2—C2—C1	−124.9 (2)	C2—O5—C5—C6	−154.45 (19)
C7—O2—C2—C3	2.7 (2)	C2—O5—C5—C4	−33.6 (2)
C5—O5—C2—O2	−99.0 (2)	O4—C4—C5—O5	−74.0 (2)
C5—O5—C2—C1	141.3 (2)	C3—C4—C5—O5	38.5 (2)
C5—O5—C2—C3	14.5 (2)	O4—C4—C5—C6	44.4 (3)
O1—C1—C2—O2	179.99 (19)	C3—C4—C5—C6	156.9 (2)
O1—C1—C2—O5	−59.8 (3)	C10—O6—C6—C5	53.1 (3)
O1—C1—C2—C3	59.8 (3)	O5—C5—C6—O6	69.7 (3)
C7—O3—C3—C4	−136.56 (19)	C4—C5—C6—O6	−45.0 (3)
C7—O3—C3—C2	−25.6 (2)	C3—O3—C7—O2	27.7 (2)
O2—C2—C3—O3	13.8 (2)	C3—O3—C7—C8	144.7 (2)
O5—C2—C3—O3	−103.3 (2)	C3—O3—C7—C9	−90.4 (2)
C1—C2—C3—O3	136.4 (2)	C2—O2—C7—O3	−18.3 (2)
O2—C2—C3—C4	127.9 (2)	C2—O2—C7—C8	−134.7 (2)
O5—C2—C3—C4	10.8 (2)	C2—O2—C7—C9	100.6 (2)
C1—C2—C3—C4	−109.5 (2)	C6—O6—C10—O4	−59.2 (3)
C10—O4—C4—C3	−162.14 (19)	C6—O6—C10—C12	−173.1 (2)
C10—O4—C4—C5	−52.7 (3)	C6—O6—C10—C11	64.8 (3)
O3—C3—C4—O4	−163.87 (17)	C4—O4—C10—O6	59.8 (3)
C2—C3—C4—O4	85.7 (2)	C4—O4—C10—C12	172.9 (2)
O3—C3—C4—C5	80.7 (2)	C4—O4—C10—C11	−64.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4	0.84	2.17	2.933 (3)	151
C1—H1A···O5^i	0.99	2.59	3.551 (3)	165
C4—H4···O1^ii	1.00	2.49	3.278 (3)	135
C8—H8A···O5^iii	0.98	2.50	3.462 (3)	166

Symmetry codes: (i) x+1/2, −y+3/2, −z; (ii) x−1, y, z; (iii) x−1/2, −y+3/2, −z.

(II) 2,3-O-isopropylidene-α-L-sorbofuranose

Crystal data

C9H16O6	F(000) = 472
Mr = 220.22	Dx = 1.385 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 7904 reflections
a = 6.7321 (3) Å	θ = 2.4–32.5°
b = 9.1945 (5) Å	µ = 0.12 mm^−1
c = 17.0658 (9) Å	T = 153 K
V = 1056.34 (9) Å^3	Irregular block, colourless
Z = 4	1.08 × 1.06 × 0.54 mm

Data collection

Siemens SMART CCD area-detector diffractometer	2219 independent reflections
Radiation source: fine-focus sealed tube	2019 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ω scans	θmax = 33.0°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −10→10
Tmin = 0.690, Tmax = 0.940	k = −13→13
19061 measured reflections	l = −25→25

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.082	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0553P)^2 + 0.0956P] where P = (Fo^2 + 2Fc^2)/3
2219 reflections	(Δ/σ)max < 0.001
141 parameters	Δρmax = 0.27 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Experimental. Data were collected at low temperature using a Siemens SMART CCD diffractometer equipped with a LT-2 device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal–to–detector distance of 3.97 cm, 1 second per frame. Preliminary orientation matrix was obtained from the first 100 frames using SMART (Siemens, 1995). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement on the position of 7904 reflections with I>10σ(I) after integration of all the frames data using SAINT (Siemens, 1995).

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
O1	1.08504 (14)	0.47499 (11)	0.13317 (5)	0.02462 (19)
H1	1.1616	0.4116	0.1517	0.037*
O2	0.79129 (14)	0.42804 (9)	−0.04444 (5)	0.02109 (17)
O3	0.57185 (13)	0.59732 (9)	0.00054 (4)	0.01970 (17)
O4	0.72499 (14)	0.53949 (9)	0.20279 (5)	0.02040 (17)
H4	0.8427	0.5189	0.1908	0.031*
O5	0.75362 (12)	0.32123 (8)	0.07773 (5)	0.01728 (16)
O6	0.34248 (14)	0.29332 (10)	0.21358 (5)	0.0252 (2)
H6	0.3025	0.2241	0.2416	0.038*
C1	1.05278 (17)	0.44662 (14)	0.05149 (8)	0.0227 (2)
H1A	1.1138	0.3525	0.0368	0.027*
H1B	1.1146	0.5241	0.0195	0.027*
C2	0.83068 (16)	0.44197 (12)	0.03653 (6)	0.01622 (19)
C3	0.70930 (17)	0.57618 (12)	0.06294 (6)	0.01656 (19)
H3	0.7937	0.6636	0.0733	0.020*
C4	0.60026 (17)	0.52195 (12)	0.13564 (6)	0.01622 (19)
H4A	0.4706	0.5735	0.1427	0.019*
C5	0.56865 (17)	0.36174 (11)	0.11392 (6)	0.01569 (19)
H5	0.4588	0.3539	0.0747	0.019*
C6	0.53096 (18)	0.25721 (12)	0.18050 (7)	0.0188 (2)
H6A	0.5299	0.1559	0.1609	0.023*
H6B	0.6366	0.2662	0.2206	0.023*
C7	0.66284 (18)	0.54490 (12)	−0.06966 (6)	0.0185 (2)
C8	0.5025 (2)	0.48565 (15)	−0.12224 (7)	0.0255 (2)
H8A	0.4255	0.4122	−0.0938	0.038*
H8B	0.5631	0.4412	−0.1686	0.038*
H8C	0.4144	0.5650	−0.1385	0.038*
C9	0.7878 (2)	0.66200 (14)	−0.10785 (8)	0.0267 (3)
H9A	0.7016	0.7413	−0.1256	0.040*
H9B	0.8587	0.6208	−0.1528	0.040*
H9C	0.8840	0.6997	−0.0698	0.040*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0192 (4)	0.0279 (4)	0.0268 (4)	0.0038 (4)	−0.0045 (3)	−0.0039 (3)
O2	0.0260 (4)	0.0209 (4)	0.0164 (3)	0.0048 (3)	0.0015 (3)	−0.0018 (3)
O3	0.0230 (4)	0.0198 (3)	0.0163 (3)	0.0050 (3)	0.0007 (3)	0.0011 (3)
O4	0.0224 (4)	0.0220 (4)	0.0168 (3)	0.0022 (3)	−0.0022 (3)	−0.0044 (3)
O5	0.0171 (4)	0.0139 (3)	0.0208 (3)	0.0020 (3)	0.0034 (3)	0.0008 (3)
O6	0.0245 (4)	0.0256 (4)	0.0254 (4)	0.0019 (3)	0.0073 (4)	0.0093 (4)
C1	0.0155 (4)	0.0274 (5)	0.0252 (5)	0.0001 (4)	0.0022 (4)	−0.0038 (4)
C2	0.0164 (4)	0.0163 (4)	0.0160 (4)	0.0007 (4)	0.0016 (4)	−0.0010 (4)
C3	0.0191 (5)	0.0139 (4)	0.0166 (4)	0.0013 (4)	0.0010 (4)	−0.0009 (3)
C4	0.0177 (4)	0.0158 (4)	0.0152 (4)	0.0027 (4)	0.0009 (4)	−0.0008 (3)
C5	0.0156 (4)	0.0155 (4)	0.0159 (4)	0.0006 (4)	0.0007 (4)	0.0006 (3)
C6	0.0205 (5)	0.0182 (4)	0.0178 (4)	0.0007 (4)	0.0018 (4)	0.0030 (4)
C7	0.0229 (5)	0.0160 (5)	0.0166 (4)	−0.0003 (4)	0.0016 (4)	0.0013 (4)
C8	0.0276 (6)	0.0257 (5)	0.0231 (5)	−0.0049 (5)	−0.0036 (5)	−0.0001 (4)
C9	0.0341 (6)	0.0223 (5)	0.0237 (5)	−0.0087 (5)	0.0041 (5)	0.0032 (4)

Geometric parameters (Å, º)

O1—C1	1.4347 (15)	C3—C4	1.5255 (15)
O1—H1	0.8400	C3—H3	1.0000
O2—C2	1.4128 (14)	C4—C5	1.5338 (15)
O2—C7	1.4448 (14)	C4—H4A	1.0000
O3—C7	1.4292 (13)	C5—C6	1.5097 (15)
O3—C3	1.4241 (14)	C5—H5	1.0000
O4—C4	1.4298 (14)	C6—H6A	0.9900
O4—H4	0.8400	C6—H6B	0.9900
O5—C2	1.4128 (13)	C7—C8	1.5057 (17)
O5—C5	1.4391 (13)	C7—C9	1.5138 (17)
O6—C6	1.4279 (14)	C8—H8A	0.9800
O6—H6	0.8400	C8—H8B	0.9800
C1—C2	1.5175 (16)	C8—H8C	0.9800
C1—H1A	0.9900	C9—H9A	0.9800
C1—H1B	0.9900	C9—H9B	0.9800
C2—C3	1.5471 (15)	C9—H9C	0.9800
C1—O1—H1	109.5	O5—C5—C6	107.68 (9)
C2—O2—C7	109.65 (8)	O5—C5—C4	103.43 (9)
C7—O3—C3	107.60 (8)	C6—C5—C4	116.93 (9)
C4—O4—H4	109.5	O5—C5—H5	109.5
C2—O5—C5	109.15 (8)	C6—C5—H5	109.5
C6—O6—H6	109.5	C4—C5—H5	109.5
O1—C1—C2	108.52 (10)	O6—C6—C5	107.39 (9)
O1—C1—H1A	110.0	O6—C6—H6A	110.2
C2—C1—H1A	110.0	C5—C6—H6A	110.2
O1—C1—H1B	110.0	O6—C6—H6B	110.2
C2—C1—H1B	110.0	C5—C6—H6B	110.2
H1A—C1—H1B	108.4	H6A—C6—H6B	108.5
O5—C2—O2	110.29 (9)	O3—C7—O2	104.93 (8)
O5—C2—C1	107.47 (9)	O3—C7—C8	108.31 (10)
O2—C2—C1	110.61 (9)	O2—C7—C8	109.73 (10)
O5—C2—C3	106.73 (8)	O3—C7—C9	111.05 (9)
O2—C2—C3	104.96 (9)	O2—C7—C9	108.94 (10)
C1—C2—C3	116.68 (10)	C8—C7—C9	113.53 (10)
O3—C3—C4	109.89 (9)	C7—C8—H8A	109.5
O3—C3—C2	103.55 (8)	C7—C8—H8B	109.5
C4—C3—C2	103.32 (9)	H8A—C8—H8B	109.5
O3—C3—H3	113.1	C7—C8—H8C	109.5
C4—C3—H3	113.1	H8A—C8—H8C	109.5
C2—C3—H3	113.1	H8B—C8—H8C	109.5
O4—C4—C5	112.55 (9)	C7—C9—H9A	109.5
O4—C4—C3	109.42 (9)	C7—C9—H9B	109.5
C5—C4—C3	100.61 (8)	H9A—C9—H9B	109.5
O4—C4—H4A	111.3	C7—C9—H9C	109.5
C5—C4—H4A	111.3	H9A—C9—H9C	109.5
C3—C4—H4A	111.3	H9B—C9—H9C	109.5
C5—O5—C2—O2	−100.87 (10)	C2—C3—C4—O4	86.04 (10)
C5—O5—C2—C1	138.48 (9)	O3—C3—C4—C5	77.35 (10)
C5—O5—C2—C3	12.61 (11)	C2—C3—C4—C5	−32.62 (10)
C7—O2—C2—O5	116.66 (9)	C2—O5—C5—C6	−158.42 (9)
C7—O2—C2—C1	−124.60 (10)	C2—O5—C5—C4	−34.03 (10)
C7—O2—C2—C3	2.05 (12)	O4—C4—C5—O5	−75.55 (11)
O1—C1—C2—O5	−65.12 (12)	C3—C4—C5—O5	40.80 (10)
O1—C1—C2—O2	174.44 (9)	O4—C4—C5—C6	42.58 (14)
O1—C1—C2—C3	54.60 (14)	C3—C4—C5—C6	158.93 (10)
C7—O3—C3—C4	−138.85 (9)	O5—C5—C6—O6	−177.09 (8)
C7—O3—C3—C2	−29.03 (10)	C4—C5—C6—O6	67.11 (13)
O5—C2—C3—O3	−100.74 (9)	C3—O3—C7—O2	30.81 (11)
O2—C2—C3—O3	16.32 (11)	C3—O3—C7—C8	147.96 (9)
C1—C2—C3—O3	139.14 (10)	C3—O3—C7—C9	−86.73 (11)
O5—C2—C3—C4	13.88 (11)	C2—O2—C7—O3	−19.73 (12)
O2—C2—C3—C4	130.95 (9)	C2—O2—C7—C8	−135.90 (10)
C1—C2—C3—C4	−106.23 (11)	C2—O2—C7—C9	99.25 (11)
O3—C3—C4—O4	−163.98 (8)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4···O1	0.84	1.95	2.7638 (13)	164
O1—H1···O6^i	0.84	1.94	2.7708 (13)	168
O6—H6···O4^ii	0.84	1.95	2.7730 (12)	165
C8—H8A···O5^iii	0.98	2.45	3.3682 (15)	155
C9—H9C···O3^iv	0.98	2.55	3.4508 (16)	154

Symmetry codes: (i) x+1, y, z; (ii) −x+1, y−1/2, −z+1/2; (iii) x−1/2, −y+1/2, −z; (iv) x+1/2, −y+3/2, −z.