organic compounds
Ethyl α-L-sorboside
aDepartment of Advanced Materials Science, Faculty of Engineering, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, Japan, and bFushimi Pharmaceutical Co Ltd, 307 Minatomachi, Marugame, Kagawa 763-8605, Japan
*Correspondence e-mail: ishii.tomohiko@kagawa-u.ac.jp
Ethyl L-sorboside, C8H16O6, was prepared from the rare sugar L-sorbose, C6H12O6, and crystallized. It was confirmed that ethyl L-sorboside formed α-pyranose with a 2C5 conformation. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming a three-dimensional network. The unit-cell volume of the title ethyl α-L-sorboside is 940.63 Å3 (Z = 4), which is about 194.69 Å3 (26.1%) bigger than that of L-sorbose [745.94 Å3 (Z = 4)].
Keywords: crystal structure; hydrogen bonding; rare sugar; alkyl sorboside.
CCDC reference: 2046786
Structure description
The rare sugar L-sorbose is the first L-form hexose found in nature (Itoh et al., 1995; Khan et al., 1992; Nordenson et al., 1979). Ethyl L-sorboside (Fig. 1) is an α-pyranose form in which the OH group located on the C-2 position in the rare sugar L-sorbose is converted into the ethoxy group OC2H5. The molecular weight of C8H16O6 is 208. On the other hand, the molecular weight of C6H12O6 is 180. So, the increase in molecular weight is about 16%. In contrast, the volume has increased by 26%. This point is characteristic. In other words, sorbose is highly crystalline and has a high density. On the other hand, the addition of the ethoxy group, which is hydrophobic, weakens inter-molecular interactions between sugar molecules, resulting in a decrease in density and an increase in volume.
In this study, we aimed to create a single crystal of ethyl L-sorboside. The is non-centrosymmetric, P212121, and there are total of four sorboside molecules in the (Z = 4). The of ethyl L-sorboside features a three-dimensional hydrogen-bonded network (Table 1), with each molecule interacting with six neighbours. There are four intermolecular hydrogen bonds and an additional intramolecular hydrogen bond (Fig. 2).
Synthesis and crystallization
Ethyl L-sorboside, α-sorbopyranoside form, was prepared by Fischer glycosidation from L-sorbose and ethanol (Taguchi et al., 2018). The Fisher method produces isomers such as α-, β-, and furanose. Therefore, chromatographic separation using an ion-exchange resin was performed. After the separation step, the solution was evaporated to syrup. Small single crystals were obtained by keeping the flask at room temperature. It is obvious that the synthesized ethyl α-L-sorbose is still in the L-form after dehydrative condensation, because L-sorbose is used as the starting material. The were also confirmed by the Flack (1983) parameter.
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 2046786
https://doi.org/10.1107/S2414314620016259/bv4033sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314620016259/bv4033Isup2.hkl
Data collection: RAPID-AUTO (Rigaku, 2009); cell
RAPID-AUTO (Rigaku, 2009); data reduction: RAPID-AUTO (Rigaku, 2009); program(s) used to solve structure: SIR2014 (Burla et al., 2015); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: CrystalStructure (Rigaku, 2019); software used to prepare material for publication: CrystalStructure (Rigaku, 2019).C8H16O6 | Dx = 1.470 Mg m−3 |
Mr = 208.21 | Cu Kα radiation, λ = 1.54187 Å |
Orthorhombic, P212121 | Cell parameters from 9046 reflections |
a = 6.8203 (8) Å | θ = 5.1–68.6° |
b = 8.6934 (10) Å | µ = 1.09 mm−1 |
c = 15.865 (2) Å | T = 296 K |
V = 940.63 (19) Å3 | Block, colorless |
Z = 4 | 0.10 × 0.10 × 0.10 mm |
F(000) = 448.00 |
Rigaku R-AXIS RAPID diffractometer | 1602 reflections with F2 > 2.0σ(F2) |
Detector resolution: 10.000 pixels mm-1 | Rint = 0.091 |
ω scans | θmax = 68.3°, θmin = 5.6° |
Absorption correction: multi-scan (ABSCOR; Rigaku, 1995) | h = −7→8 |
Tmin = 0.462, Tmax = 0.897 | k = −10→10 |
10373 measured reflections | l = −19→18 |
1721 independent reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.037 | H-atom parameters constrained |
wR(F2) = 0.090 | w = 1/[σ2(Fo2) + (0.0379P)2 + 0.0827P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
1721 reflections | Δρmax = 0.20 e Å−3 |
127 parameters | Δρmin = −0.27 e Å−3 |
0 restraints | Absolute structure: Flack x determined using 581 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.06 (12) |
Secondary atom site location: difference Fourier map |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F2. R-factor (gt) are based on F. The threshold expression of F2 > 2.0 sigma(F2) is used only for calculating R-factor (gt). H atoms were positioned geometrically (C—H = 0.98, 0.97 or 0.96 Å, and O—H = 0.82 Å) and refined using as riding with Uiso(H) = 1.2Ueq(C or O), allowing for free rotation of the OH groups. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.0029 (3) | 0.18389 (19) | 0.69407 (12) | 0.0427 (6) | |
H1 | −0.027589 | 0.171200 | 0.743583 | 0.051* | |
O2 | 0.3056 (3) | 0.46513 (18) | 0.70305 (10) | 0.0272 (4) | |
O3 | 0.0535 (3) | 0.66379 (18) | 0.63075 (10) | 0.0309 (5) | |
H3 | −0.023262 | 0.711551 | 0.600806 | 0.037* | |
O4 | 0.2892 (3) | 0.71889 (18) | 0.48325 (11) | 0.0313 (5) | |
H4 | 0.222838 | 0.785460 | 0.506192 | 0.038* | |
O5 | 0.6053 (3) | 0.51250 (18) | 0.46175 (12) | 0.0393 (6) | |
H5 | 0.633778 | 0.456529 | 0.421987 | 0.047* | |
O6 | 0.2702 (3) | 0.28944 (17) | 0.59356 (11) | 0.0257 (4) | |
C1 | −0.0118 (4) | 0.3405 (3) | 0.67368 (18) | 0.0331 (6) | |
H1A | −0.052757 | 0.397130 | 0.723326 | 0.040* | |
H1B | −0.111982 | 0.353631 | 0.630877 | 0.040* | |
C2 | 0.1802 (4) | 0.4074 (3) | 0.64149 (16) | 0.0238 (6) | |
C3 | 0.1421 (4) | 0.5445 (3) | 0.58310 (15) | 0.0225 (5) | |
H3A | 0.050371 | 0.512312 | 0.538941 | 0.027* | |
C4 | 0.3292 (4) | 0.5991 (2) | 0.54174 (16) | 0.0242 (6) | |
H4A | 0.420080 | 0.636598 | 0.584961 | 0.029* | |
C5 | 0.4209 (4) | 0.4673 (3) | 0.49524 (16) | 0.0251 (6) | |
H5A | 0.334371 | 0.435115 | 0.449203 | 0.030* | |
C6 | 0.4498 (4) | 0.3347 (3) | 0.55571 (16) | 0.0283 (6) | |
H6A | 0.505486 | 0.248021 | 0.525599 | 0.034* | |
H6B | 0.541691 | 0.364895 | 0.599347 | 0.034* | |
C7 | 0.3484 (6) | 0.3705 (3) | 0.77397 (18) | 0.0434 (8) | |
H7A | 0.392720 | 0.269868 | 0.755600 | 0.052* | |
H7B | 0.232444 | 0.357408 | 0.808608 | 0.052* | |
C8 | 0.5050 (5) | 0.4492 (4) | 0.8224 (2) | 0.0500 (9) | |
H8A | 0.538256 | 0.388699 | 0.870993 | 0.060* | |
H8B | 0.618825 | 0.461344 | 0.787445 | 0.060* | |
H8C | 0.459315 | 0.548465 | 0.840200 | 0.060* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0666 (16) | 0.0315 (10) | 0.0301 (10) | −0.0161 (9) | 0.0115 (10) | 0.0011 (8) |
O2 | 0.0373 (11) | 0.0233 (9) | 0.0210 (9) | −0.0029 (8) | −0.0068 (8) | 0.0021 (7) |
O3 | 0.0390 (12) | 0.0297 (9) | 0.0241 (9) | 0.0174 (8) | 0.0028 (9) | 0.0013 (7) |
O4 | 0.0418 (12) | 0.0220 (8) | 0.0299 (10) | 0.0040 (8) | 0.0069 (9) | 0.0058 (7) |
O5 | 0.0410 (12) | 0.0257 (9) | 0.0512 (13) | −0.0061 (8) | 0.0240 (10) | −0.0085 (9) |
O6 | 0.0287 (10) | 0.0190 (8) | 0.0292 (10) | −0.0008 (7) | 0.0060 (8) | −0.0011 (6) |
C1 | 0.0334 (16) | 0.0325 (14) | 0.0335 (15) | −0.0032 (12) | 0.0054 (13) | 0.0051 (11) |
C2 | 0.0277 (14) | 0.0217 (12) | 0.0221 (13) | 0.0013 (10) | 0.0001 (11) | −0.0003 (9) |
C3 | 0.0250 (14) | 0.0213 (11) | 0.0213 (12) | 0.0031 (10) | 0.0019 (10) | −0.0016 (10) |
C4 | 0.0292 (15) | 0.0196 (11) | 0.0239 (13) | −0.0014 (10) | 0.0021 (11) | −0.0001 (9) |
C5 | 0.0260 (14) | 0.0215 (12) | 0.0279 (14) | −0.0037 (10) | 0.0088 (11) | −0.0035 (9) |
C6 | 0.0268 (16) | 0.0236 (12) | 0.0344 (15) | 0.0044 (11) | 0.0057 (12) | −0.0015 (10) |
C7 | 0.066 (2) | 0.0321 (14) | 0.0324 (16) | −0.0072 (14) | −0.0163 (16) | 0.0080 (12) |
C8 | 0.057 (2) | 0.0532 (18) | 0.0398 (18) | −0.0050 (16) | −0.0183 (17) | 0.0121 (14) |
O1—C1 | 1.403 (3) | C2—C3 | 1.532 (3) |
O1—H1 | 0.8200 | C3—C4 | 1.512 (3) |
O2—C2 | 1.392 (3) | C3—H3A | 0.9800 |
O2—C7 | 1.424 (3) | C4—C5 | 1.499 (3) |
O3—C3 | 1.418 (3) | C4—H4A | 0.9800 |
O3—H3 | 0.8200 | C5—C6 | 1.512 (3) |
O4—C4 | 1.421 (3) | C5—H5A | 0.9800 |
O4—H4 | 0.8200 | C6—H6A | 0.9700 |
O5—C5 | 1.420 (3) | C6—H6B | 0.9700 |
O5—H5 | 0.8200 | C7—C8 | 1.483 (4) |
O6—C2 | 1.416 (3) | C7—H7A | 0.9700 |
O6—C6 | 1.419 (3) | C7—H7B | 0.9700 |
C1—C2 | 1.521 (4) | C8—H8A | 0.9600 |
C1—H1A | 0.9700 | C8—H8B | 0.9600 |
C1—H1B | 0.9700 | C8—H8C | 0.9600 |
C1—O1—H1 | 109.5 | O4—C4—H4A | 109.5 |
C2—O2—C7 | 118.2 (2) | C5—C4—H4A | 109.5 |
C3—O3—H3 | 109.5 | C3—C4—H4A | 109.5 |
C4—O4—H4 | 109.5 | O5—C5—C4 | 109.99 (19) |
C5—O5—H5 | 109.5 | O5—C5—C6 | 109.5 (2) |
C2—O6—C6 | 113.59 (17) | C4—C5—C6 | 108.94 (19) |
O1—C1—C2 | 112.8 (2) | O5—C5—H5A | 109.5 |
O1—C1—H1A | 109.0 | C4—C5—H5A | 109.5 |
C2—C1—H1A | 109.0 | C6—C5—H5A | 109.5 |
O1—C1—H1B | 109.0 | O6—C6—C5 | 111.6 (2) |
C2—C1—H1B | 109.0 | O6—C6—H6A | 109.3 |
H1A—C1—H1B | 107.8 | C5—C6—H6A | 109.3 |
O2—C2—O6 | 111.8 (2) | O6—C6—H6B | 109.3 |
O2—C2—C1 | 115.5 (2) | C5—C6—H6B | 109.3 |
O6—C2—C1 | 106.1 (2) | H6A—C6—H6B | 108.0 |
O2—C2—C3 | 104.35 (19) | O2—C7—C8 | 106.9 (2) |
O6—C2—C3 | 108.20 (18) | O2—C7—H7A | 110.3 |
C1—C2—C3 | 110.8 (2) | C8—C7—H7A | 110.3 |
O3—C3—C4 | 111.19 (19) | O2—C7—H7B | 110.3 |
O3—C3—C2 | 108.60 (18) | C8—C7—H7B | 110.3 |
C4—C3—C2 | 111.3 (2) | H7A—C7—H7B | 108.6 |
O3—C3—H3A | 108.6 | C7—C8—H8A | 109.5 |
C4—C3—H3A | 108.6 | C7—C8—H8B | 109.5 |
C2—C3—H3A | 108.6 | H8A—C8—H8B | 109.5 |
O4—C4—C5 | 108.6 (2) | C7—C8—H8C | 109.5 |
O4—C4—C3 | 110.6 (2) | H8A—C8—H8C | 109.5 |
C5—C4—C3 | 109.02 (19) | H8B—C8—H8C | 109.5 |
C7—O2—C2—O6 | −71.6 (3) | C1—C2—C3—C4 | −172.6 (2) |
C7—O2—C2—C1 | 49.9 (3) | O3—C3—C4—O4 | −63.0 (2) |
C7—O2—C2—C3 | 171.7 (2) | C2—C3—C4—O4 | 175.78 (17) |
C6—O6—C2—O2 | −55.5 (2) | O3—C3—C4—C5 | 177.69 (19) |
C6—O6—C2—C1 | 177.7 (2) | C2—C3—C4—C5 | 56.5 (3) |
C6—O6—C2—C3 | 58.9 (3) | O4—C4—C5—O5 | 64.3 (3) |
O1—C1—C2—O2 | −88.5 (3) | C3—C4—C5—O5 | −175.1 (2) |
O1—C1—C2—O6 | 36.0 (3) | O4—C4—C5—C6 | −175.7 (2) |
O1—C1—C2—C3 | 153.2 (2) | C3—C4—C5—C6 | −55.2 (3) |
O2—C2—C3—O3 | −60.3 (2) | C2—O6—C6—C5 | −60.9 (3) |
O6—C2—C3—O3 | −179.47 (19) | O5—C5—C6—O6 | 177.60 (19) |
C1—C2—C3—O3 | 64.7 (3) | C4—C5—C6—O6 | 57.3 (3) |
O2—C2—C3—C4 | 62.5 (2) | C2—O2—C7—C8 | 172.0 (2) |
O6—C2—C3—C4 | −56.7 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O3i | 0.82 | 2.00 | 2.811 (3) | 169 |
O3—H3···O4ii | 0.82 | 1.94 | 2.750 (3) | 167 |
O4—H4···O3 | 0.82 | 2.52 | 2.879 (2) | 108 |
O4—H4···O5ii | 0.82 | 2.00 | 2.791 (2) | 163 |
O5—H5···O6iii | 0.82 | 2.35 | 2.988 (2) | 136 |
Symmetry codes: (i) −x, y−1/2, −z+3/2; (ii) x−1/2, −y+3/2, −z+1; (iii) x+1/2, −y+1/2, −z+1. |
Acknowledgements
The authors are sincerely grateful to Professor Genta Sakane (Okayama University of Science) for excellent discussion and useful technical advice.
Funding information
The authors are grateful to Grants-in-Aid for Rare Sugar Research of Kagawa University and the Strategic Foundational Technology Improvement Support Operation (Supporting Industry Program) for financial support.
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