organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2414-3146

Ethyl α-L-sorboside

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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

Edited by R. J. Butcher, Howard University, USA (Received 30 November 2020; accepted 15 December 2020; online 18 December 2020)

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)].

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

The rare sugar L-sorbose is the first L-form hexose found in nature (Itoh et al., 1995[Itoh, H., Sato, T., Takeuchi, T., Khan, A. R. & Izumori, K. (1995). J. Ferment. Bioeng. 79, 184-185.]; Khan et al., 1992[Khan, A. R., Takahata, S., Okaya, H., Tsumura, T. & Izumori, K. (1992). J. Ferment. Bioeng. 74, 149-152.]; Nordenson et al., 1979[Nordenson, S., Takagi, S. & Jeffrey, G. A. (1979). Acta Cryst. B35, 1005-1007.]). Ethyl L-sorboside (Fig. 1[link]) 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.

[Figure 1]
Figure 1
An ORTEP view of the title compound with the atom-labelling scheme. The displacement ellipsoids of all non-hydrogen atoms are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radii.

In this study, we aimed to create a single crystal of ethyl L-sorboside. The space group is non-centrosymmetric, P212121, and there are total of four sorboside mol­ecules in the unit cell (Z = 4). The crystal structure of ethyl L-sorboside features a three-dimensional hydrogen-bonded network (Table 1[link]), with each mol­ecule inter­acting with six neighbours. There are four inter­molecular hydrogen bonds and an additional intra­molecular hydrogen bond (Fig. 2[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA 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-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (ii) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]; (iii) [x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1].
[Figure 2]
Figure 2
A packing diagram of the title compound, showing the hydrogen-bonding network (dotted lines).

Synthesis and crystallization

Ethyl L-sorboside, α-sorbo­pyran­oside form, was prepared by Fischer glycosidation from L-sorbose and ethanol (Taguchi et al., 2018[Taguchi, H., Sogo, K., Ishii, T., Yoshihara, A. & Fukada, K. (2018). IUCrData, 3, x180114.]). 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 absolute structure were also confirmed by the Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]) parameter.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C8H16O6
Mr 208.21
Crystal system, space group Orthorhombic, P212121
Temperature (K) 296
a, b, c (Å) 6.8203 (8), 8.6934 (10), 15.865 (2)
V3) 940.63 (19)
Z 4
Radiation type Cu Kα
μ (mm−1) 1.09
Crystal size (mm) 0.10 × 0.10 × 0.10
 
Data collection
Diffractometer Rigaku R-AXIS RAPID
Absorption correction Multi-scan (ABSCOR; Rigaku, 1995[Rigaku (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan.])
Tmin, Tmax 0.462, 0.897
No. of measured, independent and observed [F2 > 2.0σ(F2)] reflections 10373, 1721, 1602
Rint 0.091
(sin θ/λ)max−1) 0.602
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.090, 1.07
No. of reflections 1721
No. of parameters 127
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.20, −0.27
Absolute structure Flack x determined using 581 quotients [(I+)−(I)]/[(I+)+(I)] (Parsons et al., 2013[Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249-259.])
Absolute structure parameter 0.06 (12)
Computer programs: RAPID-AUTO (Rigaku, 2009[Rigaku (2009). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan.]), SIR2014 (Burla et al., 2015[Burla, M. C., Caliandro, R., Carrozzini, B., Cascarano, G. L., Cuocci, C., Giacovazzo, C., Mallamo, M., Mazzone, A. & Polidori, G. (2015). J. Appl. Cryst. 48, 306-309.]), SHELXL2018/3 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]) and CrystalStructure (Rigaku, 2019[Rigaku (2019). CrystalStructure. Rigaku Corporation, Tokyo, Japan.]).

Structural data


Computing details top

Data collection: RAPID-AUTO (Rigaku, 2009); cell refinement: 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).

Ethyl α-L-sorboside top
Crystal data top
C8H16O6Dx = 1.470 Mg m3
Mr = 208.21Cu Kα radiation, λ = 1.54187 Å
Orthorhombic, P212121Cell parameters from 9046 reflections
a = 6.8203 (8) Åθ = 5.1–68.6°
b = 8.6934 (10) ŵ = 1.09 mm1
c = 15.865 (2) ÅT = 296 K
V = 940.63 (19) Å3Block, colorless
Z = 40.10 × 0.10 × 0.10 mm
F(000) = 448.00
Data collection top
Rigaku R-AXIS RAPID
diffractometer
1602 reflections with F2 > 2.0σ(F2)
Detector resolution: 10.000 pixels mm-1Rint = 0.091
ω scansθmax = 68.3°, θmin = 5.6°
Absorption correction: multi-scan
(ABSCOR; Rigaku, 1995)
h = 78
Tmin = 0.462, Tmax = 0.897k = 1010
10373 measured reflectionsl = 1918
1721 independent reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.037H-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 reflectionsΔρmax = 0.20 e Å3
127 parametersΔρmin = 0.27 e Å3
0 restraintsAbsolute structure: Flack x determined using 581 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.06 (12)
Secondary atom site location: difference Fourier map
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.0029 (3)0.18389 (19)0.69407 (12)0.0427 (6)
H10.0275890.1712000.7435830.051*
O20.3056 (3)0.46513 (18)0.70305 (10)0.0272 (4)
O30.0535 (3)0.66379 (18)0.63075 (10)0.0309 (5)
H30.0232620.7115510.6008060.037*
O40.2892 (3)0.71889 (18)0.48325 (11)0.0313 (5)
H40.2228380.7854600.5061920.038*
O50.6053 (3)0.51250 (18)0.46175 (12)0.0393 (6)
H50.6337780.4565290.4219870.047*
O60.2702 (3)0.28944 (17)0.59356 (11)0.0257 (4)
C10.0118 (4)0.3405 (3)0.67368 (18)0.0331 (6)
H1A0.0527570.3971300.7233260.040*
H1B0.1119820.3536310.6308770.040*
C20.1802 (4)0.4074 (3)0.64149 (16)0.0238 (6)
C30.1421 (4)0.5445 (3)0.58310 (15)0.0225 (5)
H3A0.0503710.5123120.5389410.027*
C40.3292 (4)0.5991 (2)0.54174 (16)0.0242 (6)
H4A0.4200800.6365980.5849610.029*
C50.4209 (4)0.4673 (3)0.49524 (16)0.0251 (6)
H5A0.3343710.4351150.4492030.030*
C60.4498 (4)0.3347 (3)0.55571 (16)0.0283 (6)
H6A0.5054860.2480210.5255990.034*
H6B0.5416910.3648950.5993470.034*
C70.3484 (6)0.3705 (3)0.77397 (18)0.0434 (8)
H7A0.3927200.2698680.7556000.052*
H7B0.2324440.3574080.8086080.052*
C80.5050 (5)0.4492 (4)0.8224 (2)0.0500 (9)
H8A0.5382560.3886990.8709930.060*
H8B0.6188250.4613440.7874450.060*
H8C0.4593150.5484650.8402000.060*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0666 (16)0.0315 (10)0.0301 (10)0.0161 (9)0.0115 (10)0.0011 (8)
O20.0373 (11)0.0233 (9)0.0210 (9)0.0029 (8)0.0068 (8)0.0021 (7)
O30.0390 (12)0.0297 (9)0.0241 (9)0.0174 (8)0.0028 (9)0.0013 (7)
O40.0418 (12)0.0220 (8)0.0299 (10)0.0040 (8)0.0069 (9)0.0058 (7)
O50.0410 (12)0.0257 (9)0.0512 (13)0.0061 (8)0.0240 (10)0.0085 (9)
O60.0287 (10)0.0190 (8)0.0292 (10)0.0008 (7)0.0060 (8)0.0011 (6)
C10.0334 (16)0.0325 (14)0.0335 (15)0.0032 (12)0.0054 (13)0.0051 (11)
C20.0277 (14)0.0217 (12)0.0221 (13)0.0013 (10)0.0001 (11)0.0003 (9)
C30.0250 (14)0.0213 (11)0.0213 (12)0.0031 (10)0.0019 (10)0.0016 (10)
C40.0292 (15)0.0196 (11)0.0239 (13)0.0014 (10)0.0021 (11)0.0001 (9)
C50.0260 (14)0.0215 (12)0.0279 (14)0.0037 (10)0.0088 (11)0.0035 (9)
C60.0268 (16)0.0236 (12)0.0344 (15)0.0044 (11)0.0057 (12)0.0015 (10)
C70.066 (2)0.0321 (14)0.0324 (16)0.0072 (14)0.0163 (16)0.0080 (12)
C80.057 (2)0.0532 (18)0.0398 (18)0.0050 (16)0.0183 (17)0.0121 (14)
Geometric parameters (Å, º) top
O1—C11.403 (3)C2—C31.532 (3)
O1—H10.8200C3—C41.512 (3)
O2—C21.392 (3)C3—H3A0.9800
O2—C71.424 (3)C4—C51.499 (3)
O3—C31.418 (3)C4—H4A0.9800
O3—H30.8200C5—C61.512 (3)
O4—C41.421 (3)C5—H5A0.9800
O4—H40.8200C6—H6A0.9700
O5—C51.420 (3)C6—H6B0.9700
O5—H50.8200C7—C81.483 (4)
O6—C21.416 (3)C7—H7A0.9700
O6—C61.419 (3)C7—H7B0.9700
C1—C21.521 (4)C8—H8A0.9600
C1—H1A0.9700C8—H8B0.9600
C1—H1B0.9700C8—H8C0.9600
C1—O1—H1109.5O4—C4—H4A109.5
C2—O2—C7118.2 (2)C5—C4—H4A109.5
C3—O3—H3109.5C3—C4—H4A109.5
C4—O4—H4109.5O5—C5—C4109.99 (19)
C5—O5—H5109.5O5—C5—C6109.5 (2)
C2—O6—C6113.59 (17)C4—C5—C6108.94 (19)
O1—C1—C2112.8 (2)O5—C5—H5A109.5
O1—C1—H1A109.0C4—C5—H5A109.5
C2—C1—H1A109.0C6—C5—H5A109.5
O1—C1—H1B109.0O6—C6—C5111.6 (2)
C2—C1—H1B109.0O6—C6—H6A109.3
H1A—C1—H1B107.8C5—C6—H6A109.3
O2—C2—O6111.8 (2)O6—C6—H6B109.3
O2—C2—C1115.5 (2)C5—C6—H6B109.3
O6—C2—C1106.1 (2)H6A—C6—H6B108.0
O2—C2—C3104.35 (19)O2—C7—C8106.9 (2)
O6—C2—C3108.20 (18)O2—C7—H7A110.3
C1—C2—C3110.8 (2)C8—C7—H7A110.3
O3—C3—C4111.19 (19)O2—C7—H7B110.3
O3—C3—C2108.60 (18)C8—C7—H7B110.3
C4—C3—C2111.3 (2)H7A—C7—H7B108.6
O3—C3—H3A108.6C7—C8—H8A109.5
C4—C3—H3A108.6C7—C8—H8B109.5
C2—C3—H3A108.6H8A—C8—H8B109.5
O4—C4—C5108.6 (2)C7—C8—H8C109.5
O4—C4—C3110.6 (2)H8A—C8—H8C109.5
C5—C4—C3109.02 (19)H8B—C8—H8C109.5
C7—O2—C2—O671.6 (3)C1—C2—C3—C4172.6 (2)
C7—O2—C2—C149.9 (3)O3—C3—C4—O463.0 (2)
C7—O2—C2—C3171.7 (2)C2—C3—C4—O4175.78 (17)
C6—O6—C2—O255.5 (2)O3—C3—C4—C5177.69 (19)
C6—O6—C2—C1177.7 (2)C2—C3—C4—C556.5 (3)
C6—O6—C2—C358.9 (3)O4—C4—C5—O564.3 (3)
O1—C1—C2—O288.5 (3)C3—C4—C5—O5175.1 (2)
O1—C1—C2—O636.0 (3)O4—C4—C5—C6175.7 (2)
O1—C1—C2—C3153.2 (2)C3—C4—C5—C655.2 (3)
O2—C2—C3—O360.3 (2)C2—O6—C6—C560.9 (3)
O6—C2—C3—O3179.47 (19)O5—C5—C6—O6177.60 (19)
C1—C2—C3—O364.7 (3)C4—C5—C6—O657.3 (3)
O2—C2—C3—C462.5 (2)C2—O2—C7—C8172.0 (2)
O6—C2—C3—C456.7 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O3i0.822.002.811 (3)169
O3—H3···O4ii0.821.942.750 (3)167
O4—H4···O30.822.522.879 (2)108
O4—H4···O5ii0.822.002.791 (2)163
O5—H5···O6iii0.822.352.988 (2)136
Symmetry codes: (i) x, y1/2, z+3/2; (ii) x1/2, 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.

References

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First citationNordenson, S., Takagi, S. & Jeffrey, G. A. (1979). Acta Cryst. B35, 1005–1007.  CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
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