In the title compounds, C
12H
20O
6, (I), and C
9H
16O
6, (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 –CH
2OH group at the C1-furanose position by another group can considerably affect the conformation of the 1,3-dioxolane ring.
Supporting information
CCDC references: 730099; 730100
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).
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 Uiso(H) =
1.2Ueq(C), 1.5Ueq(Cmethyl) and 1.5Ueq(O).
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).
(I) 2,3:4,6-di-
O-isopropylidene-
α-L-sorbofuranose
top
Crystal data top
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) Å3 | Irregular block, colourless |
Z = 4 | 0.78 × 0.48 × 0.32 mm |
Data collection top
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 top
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)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.098 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0661P)2 + 0.1325P] where P = (Fo2 + 2Fc2)/3 |
1483 reflections | (Δ/σ)max < 0.001 |
168 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
Crystal data top
C12H20O6 | V = 1371.1 (6) Å3 |
Mr = 260.28 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 6.7203 (16) Å | µ = 0.10 mm−1 |
b = 9.286 (2) Å | T = 153 K |
c = 21.972 (5) Å | 0.78 × 0.48 × 0.32 mm |
Data collection top
Siemens SMART CCD area-detector diffractometer | 1483 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 1236 reflections with I > 2σ(I) |
Tmin = 0.440, Tmax = 0.969 | Rint = 0.067 |
15054 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.037 | 0 restraints |
wR(F2) = 0.098 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.20 e Å−3 |
1483 reflections | Δρmin = −0.24 e Å−3 |
168 parameters | |
Special details top
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 (Å2) top | 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 (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
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) top
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) top
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···O5i | 0.99 | 2.59 | 3.551 (3) | 165 |
C4—H4···O1ii | 1.00 | 2.49 | 3.278 (3) | 135 |
C8—H8A···O5iii | 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
top
Crystal data top
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) Å3 | Irregular block, colourless |
Z = 4 | 1.08 × 1.06 × 0.54 mm |
Data collection top
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 top
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)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.00 | w = 1/[σ2(Fo2) + (0.0553P)2 + 0.0956P] where P = (Fo2 + 2Fc2)/3 |
2219 reflections | (Δ/σ)max < 0.001 |
141 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
Crystal data top
C9H16O6 | V = 1056.34 (9) Å3 |
Mr = 220.22 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 6.7321 (3) Å | µ = 0.12 mm−1 |
b = 9.1945 (5) Å | T = 153 K |
c = 17.0658 (9) Å | 1.08 × 1.06 × 0.54 mm |
Data collection top
Siemens SMART CCD area-detector diffractometer | 2219 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2019 reflections with I > 2σ(I) |
Tmin = 0.690, Tmax = 0.940 | Rint = 0.037 |
19061 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.082 | H-atom parameters constrained |
S = 1.00 | Δρmax = 0.27 e Å−3 |
2219 reflections | Δρmin = −0.23 e Å−3 |
141 parameters | |
Special details top
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 (Å2) top | 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 (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
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) top
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) top
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···O6i | 0.84 | 1.94 | 2.7708 (13) | 168 |
O6—H6···O4ii | 0.84 | 1.95 | 2.7730 (12) | 165 |
C8—H8A···O5iii | 0.98 | 2.45 | 3.3682 (15) | 155 |
C9—H9C···O3iv | 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. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C12H20O6 | C9H16O6 |
Mr | 260.28 | 220.22 |
Crystal system, space group | Orthorhombic, P212121 | Orthorhombic, P212121 |
Temperature (K) | 153 | 153 |
a, b, c (Å) | 6.7203 (16), 9.286 (2), 21.972 (5) | 6.7321 (3), 9.1945 (5), 17.0658 (9) |
V (Å3) | 1371.1 (6) | 1056.34 (9) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.10 | 0.12 |
Crystal size (mm) | 0.78 × 0.48 × 0.32 | 1.08 × 1.06 × 0.54 |
|
Data collection |
Diffractometer | Siemens SMART CCD area-detector diffractometer | Siemens SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.440, 0.969 | 0.690, 0.940 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15054, 1483, 1236 | 19061, 2219, 2019 |
Rint | 0.067 | 0.037 |
(sin θ/λ)max (Å−1) | 0.603 | 0.765 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.098, 1.00 | 0.031, 0.082, 1.00 |
No. of reflections | 1483 | 2219 |
No. of parameters | 168 | 141 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.20, −0.24 | 0.27, −0.23 |
Hydrogen-bond geometry (Å, º) for (I) top
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···O5i | 0.99 | 2.59 | 3.551 (3) | 165 |
C4—H4···O1ii | 1.00 | 2.49 | 3.278 (3) | 135 |
C8—H8A···O5iii | 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. |
Hydrogen-bonding geometry for (II) (Å, °) topLabel | D—H···A | | D—H | H···A | D···A | D—H···A |
a | O4—H4···O1 | | 0.84 | 1.95 | 2.7638 (13) | 164 |
b | O1—H1···O6i | | 0.84 | 1.94 | 2.7708 (13) | 168 |
c | O6—H6···O4ii | | 0.84 | 1.95 | 2.7730 (12) | 165 |
d | C8—H8A···O5iii | | 0.98 | 2.45 | 3.3682 (15) | 155 |
e | C9—H9C···O3iv | | 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. |
Selected torsion angles (°) for (I) and (II). top | (I) | (II) |
O2—C2—C3—O3 | 13.8 (2) | 16.32 (11) |
C7-O3—C3—C2 | -25.6 (2) | -29.03 (10) |
C3—O3—C7—O2 | 27.7 (2) | 30.81 (11) |
C2—O2—C7—O3 | -18.3 (2) | -19.73 (12) |
C7—O2—C2—C3 | 2.7 (2) | 2.05 (12) |
| | |
O5—C2—C3—C4 | 10.8 (2) | 13.88 (11) |
C2—C3—C4—C5 | -29.7 (2) | -32.62 (10) |
C3—C4—C5—O5 | 38.5 (2) | 40.80 (10) |
C2—O5—C5—C4 | -33.6 (2) | -34.03 (10) |
C5—O5—C2—C3 | 14.5 (2) | 12.61 (11) |
| | |
O4—C4—C5—C6 | 44.4 (3) | |
C4—C5—C6—O6 | -45.0 (3) | |
C10—O6—C6—C5 | 53.1 (3) | |
C6—O6—C10—O4 | -59.2 (3) | |
C4—O4—C10—O6 | 59.8 (3) | |
C10—O4—C4—C5 | -52.7 (3) | |
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 (EO3) 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 (C5TC4) 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 (O4CC6) 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 (EO3) 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 (C5TC4) 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 PtIV 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.