Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106021603/av3012sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106021603/av3012Isup2.hkl |
CCDC reference: 618613
The synthesis of (I) was performed starting from L-rhamnose using the methodology described by Rainer et al. (1992) and Norberg et al. (1986). Compound (I) has previously been prepared via a different route (Byramova et al., 1985). The synthesis product was analyzed with MALDI-MS: [M+Na]+ m/z, calculated for C17H22NaO6: 345.13; found: 345.26. 1H and 13C NMR data of (I) referenced to internal TMS (δ = 0.0) in CDCl3 solution at 298 K were assigned by one- and two-dimensional NMR spectroscopy techniques using a Varian Inova spectrometer operating at a proton frequency of 600 MHz. The monosaccharide was dissolved in hot ethanol and an excess of n-pentane was added at ambient temperature. Crystals for X-ray crystallographic analysis were formed at 253 K. The scattering power of the crystals was weak. Thus, it was decided to collect data with synchrotron radiation on beamline I711 at the Swedish synchrotron radiation facility, MAXLAB, Lund, Sweden.
H atoms were positioned geometrically and allowed to ride on their parent atoms, with CH, CH3 and aromatic C—H bonds of 1.00, 0.98 and 0.95 Å, respectively, and with Uiso(H) = Ueq(C), or 1.5Ueq(C) for methyl H. [Please check added text] The Flack parameter (Flack, 1983) derived from the refinement using unmerged data [x = 0.43 (15)] was inconclusive. Thus, the reflection data were merged in the final refinement. The absolute configuration was set by the a priori knowledge of the absolute configuration of the synthesis components.
Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: PLATON (Spek, 2003).
C17H22O6 | F(000) = 688 |
Mr = 322.35 | Dx = 1.282 Mg m−3 |
Orthorhombic, P212121 | Synchrotron radiation, λ = 1.350 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 999 reflections |
a = 9.720 (8) Å | θ = 3.0–29.0° |
b = 10.654 (11) Å | µ = 0.52 mm−1 |
c = 16.127 (14) Å | T = 100 K |
V = 1670 (3) Å3 | Prism, colourless |
Z = 4 | 0.15 × 0.10 × 0.08 mm |
Bruker SMART 1K area-detector diffractometer | 2244 independent reflections |
Radiation source: Beamline I711, Maxlab, Lund, Sweden | 2133 reflections with I > 2σ(I) |
Silicon monochromator | Rint = 0.095 |
Detector resolution: 10 pixels mm-1 | θmax = 63.4°, θmin = 4.4° |
ω scan at different ϕ and 2θ | h = −12→12 |
Absorption correction: part of the refinement model (ΔF) (SADABS; Sheldrick, 2002) | k = −13→12 |
Tmin = 0.98, Tmax = 1.00 | l = −21→20 |
18820 measured reflections |
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)] = 0.033 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.088 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0492P)2 + 0.241P] where P = (Fo2 + 2Fc2)/3 |
2244 reflections | (Δ/σ)max < 0.001 |
212 parameters | Δρmax = 0.26 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
C17H22O6 | V = 1670 (3) Å3 |
Mr = 322.35 | Z = 4 |
Orthorhombic, P212121 | Synchrotron radiation, λ = 1.350 Å |
a = 9.720 (8) Å | µ = 0.52 mm−1 |
b = 10.654 (11) Å | T = 100 K |
c = 16.127 (14) Å | 0.15 × 0.10 × 0.08 mm |
Bruker SMART 1K area-detector diffractometer | 2244 independent reflections |
Absorption correction: part of the refinement model (ΔF) (SADABS; Sheldrick, 2002) | 2133 reflections with I > 2σ(I) |
Tmin = 0.98, Tmax = 1.00 | Rint = 0.095 |
18820 measured reflections |
R[F2 > 2σ(F2)] = 0.033 | 0 restraints |
wR(F2) = 0.088 | H-atom parameters constrained |
S = 1.08 | Δρmax = 0.26 e Å−3 |
2244 reflections | Δρmin = −0.21 e Å−3 |
212 parameters |
Experimental. Absolute structure known from synthesis. |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.40567 (16) | 0.16439 (16) | 0.43467 (10) | 0.0149 (3) | |
H1 | 0.3319 | 0.1155 | 0.4634 | 0.015* | |
C2 | 0.34421 (15) | 0.22351 (16) | 0.35718 (9) | 0.0139 (3) | |
H2 | 0.2911 | 0.3005 | 0.3724 | 0.014* | |
C3 | 0.44466 (16) | 0.25333 (15) | 0.28705 (9) | 0.0152 (3) | |
H3 | 0.4805 | 0.3408 | 0.2932 | 0.015* | |
C4 | 0.56396 (16) | 0.16052 (15) | 0.28293 (10) | 0.0149 (3) | |
H4 | 0.5315 | 0.0791 | 0.2591 | 0.015* | |
C5 | 0.62472 (16) | 0.13851 (16) | 0.36931 (10) | 0.0166 (3) | |
H5 | 0.6538 | 0.2201 | 0.3945 | 0.017* | |
C6 | 0.74363 (18) | 0.04612 (18) | 0.36988 (11) | 0.0223 (3) | |
H6A | 0.7804 | 0.0391 | 0.4263 | 0.022* | |
H6B | 0.8161 | 0.0759 | 0.3325 | 0.022* | |
H6C | 0.7111 | −0.0363 | 0.3512 | 0.022* | |
C7 | 0.23802 (17) | 0.17501 (17) | 0.23437 (10) | 0.0180 (3) | |
C8 | 0.2254 (2) | 0.0600 (2) | 0.17966 (11) | 0.0302 (4) | |
H8A | 0.1422 | 0.0133 | 0.1947 | 0.030* | |
H8B | 0.3062 | 0.0063 | 0.1874 | 0.030* | |
H8C | 0.2197 | 0.0861 | 0.1215 | 0.030* | |
C9 | 0.11593 (17) | 0.26332 (19) | 0.22673 (11) | 0.0238 (4) | |
H9A | 0.0311 | 0.2179 | 0.2401 | 0.024* | |
H9B | 0.1106 | 0.2954 | 0.1699 | 0.024* | |
H9C | 0.1274 | 0.3336 | 0.2653 | 0.024* | |
C10 | 0.72022 (16) | 0.14471 (16) | 0.16789 (10) | 0.0150 (3) | |
C11 | 0.80582 (15) | 0.21873 (16) | 0.10960 (9) | 0.0137 (3) | |
C12 | 0.87984 (18) | 0.15474 (17) | 0.04875 (10) | 0.0191 (3) | |
H12 | 0.8750 | 0.0658 | 0.0458 | 0.019* | |
C13 | 0.96073 (19) | 0.22041 (19) | −0.00766 (11) | 0.0245 (4) | |
H13 | 1.0108 | 0.1766 | −0.0492 | 0.024* | |
C14 | 0.96792 (19) | 0.35107 (18) | −0.00285 (11) | 0.0229 (4) | |
H14 | 1.0236 | 0.3964 | −0.0409 | 0.023* | |
C15 | 0.89381 (17) | 0.41507 (17) | 0.05756 (11) | 0.0194 (3) | |
H15 | 0.8990 | 0.5040 | 0.0605 | 0.019* | |
C16 | 0.81219 (16) | 0.34999 (16) | 0.11373 (10) | 0.0155 (3) | |
H16 | 0.7611 | 0.3941 | 0.1546 | 0.016* | |
C17 | 0.4911 (2) | 0.22159 (18) | 0.56583 (10) | 0.0235 (4) | |
H17A | 0.5180 | 0.2937 | 0.5999 | 0.035* | |
H17B | 0.5704 | 0.1658 | 0.5585 | 0.035* | |
H17C | 0.4166 | 0.1757 | 0.5934 | 0.035* | |
O1 | 0.44505 (12) | 0.26463 (11) | 0.48656 (7) | 0.0177 (2) | |
O2 | 0.25509 (12) | 0.13414 (11) | 0.31830 (7) | 0.0165 (2) | |
O3 | 0.36144 (12) | 0.24391 (12) | 0.21417 (7) | 0.0193 (3) | |
O4 | 0.66485 (11) | 0.21687 (12) | 0.22819 (7) | 0.0167 (2) | |
O5 | 0.51651 (11) | 0.08257 (11) | 0.41771 (7) | 0.0165 (2) | |
O10 | 0.70053 (14) | 0.03238 (12) | 0.16229 (8) | 0.0227 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0159 (7) | 0.0132 (7) | 0.0157 (7) | −0.0003 (6) | −0.0006 (5) | 0.0003 (6) |
C2 | 0.0147 (7) | 0.0116 (7) | 0.0154 (7) | −0.0007 (6) | 0.0003 (5) | 0.0024 (5) |
C3 | 0.0160 (7) | 0.0129 (8) | 0.0168 (7) | −0.0005 (6) | 0.0004 (5) | 0.0025 (5) |
C4 | 0.0154 (6) | 0.0109 (7) | 0.0184 (7) | −0.0011 (6) | 0.0024 (6) | 0.0012 (6) |
C5 | 0.0161 (7) | 0.0147 (8) | 0.0189 (7) | −0.0005 (6) | 0.0003 (6) | 0.0008 (6) |
C6 | 0.0206 (8) | 0.0210 (9) | 0.0254 (8) | 0.0047 (7) | −0.0029 (6) | 0.0000 (7) |
C7 | 0.0193 (7) | 0.0191 (8) | 0.0156 (7) | −0.0033 (7) | −0.0018 (6) | 0.0039 (6) |
C8 | 0.0413 (11) | 0.0278 (10) | 0.0215 (8) | −0.0051 (8) | −0.0038 (7) | −0.0048 (7) |
C9 | 0.0172 (7) | 0.0312 (10) | 0.0231 (8) | −0.0011 (7) | −0.0047 (6) | 0.0077 (7) |
C10 | 0.0159 (7) | 0.0127 (8) | 0.0164 (7) | 0.0003 (5) | −0.0019 (5) | −0.0010 (6) |
C11 | 0.0125 (6) | 0.0135 (7) | 0.0150 (7) | 0.0006 (6) | −0.0007 (5) | −0.0011 (6) |
C12 | 0.0231 (8) | 0.0146 (8) | 0.0197 (7) | 0.0012 (6) | 0.0012 (6) | −0.0037 (6) |
C13 | 0.0273 (8) | 0.0243 (9) | 0.0218 (8) | 0.0022 (7) | 0.0079 (7) | −0.0047 (7) |
C14 | 0.0230 (8) | 0.0233 (10) | 0.0226 (8) | −0.0013 (7) | 0.0052 (6) | 0.0031 (7) |
C15 | 0.0201 (7) | 0.0138 (8) | 0.0245 (8) | −0.0002 (6) | 0.0014 (6) | 0.0009 (6) |
C16 | 0.0148 (7) | 0.0123 (8) | 0.0194 (7) | 0.0004 (6) | −0.0002 (6) | −0.0015 (6) |
C17 | 0.0312 (9) | 0.0218 (9) | 0.0175 (8) | 0.0000 (7) | −0.0065 (7) | 0.0006 (7) |
O1 | 0.0242 (6) | 0.0139 (6) | 0.0151 (5) | 0.0005 (5) | −0.0020 (4) | −0.0002 (4) |
O2 | 0.0194 (6) | 0.0154 (6) | 0.0147 (5) | −0.0042 (5) | −0.0021 (4) | 0.0035 (4) |
O3 | 0.0181 (5) | 0.0243 (7) | 0.0154 (5) | −0.0007 (5) | −0.0002 (4) | 0.0063 (5) |
O4 | 0.0180 (5) | 0.0115 (6) | 0.0205 (5) | −0.0028 (4) | 0.0054 (4) | −0.0022 (4) |
O5 | 0.0189 (5) | 0.0110 (5) | 0.0195 (5) | 0.0014 (4) | 0.0009 (4) | 0.0025 (4) |
O10 | 0.0342 (7) | 0.0103 (6) | 0.0235 (6) | −0.0024 (5) | 0.0047 (5) | −0.0017 (5) |
C1—O1 | 1.410 (2) | C8—H8B | 0.9800 |
C1—O5 | 1.413 (2) | C8—H8C | 0.9800 |
C1—C2 | 1.522 (2) | C9—H9A | 0.9800 |
C1—H1 | 1.0000 | C9—H9B | 0.9800 |
C2—O2 | 1.432 (2) | C9—H9C | 0.9800 |
C2—C3 | 1.527 (2) | C10—O10 | 1.215 (3) |
C2—H2 | 1.0000 | C10—O4 | 1.352 (2) |
C3—O3 | 1.430 (2) | C10—C11 | 1.482 (2) |
C3—C4 | 1.525 (2) | C11—C12 | 1.395 (2) |
C3—H3 | 1.0000 | C11—C16 | 1.401 (3) |
C4—O4 | 1.449 (2) | C12—C13 | 1.391 (3) |
C4—C5 | 1.531 (2) | C12—H12 | 0.9500 |
C4—H4 | 1.0000 | C13—C14 | 1.396 (3) |
C5—O5 | 1.439 (2) | C13—H13 | 0.9500 |
C5—C6 | 1.518 (2) | C14—C15 | 1.390 (2) |
C5—H5 | 1.0000 | C14—H14 | 0.9500 |
C6—H6A | 0.9800 | C15—C16 | 1.390 (2) |
C6—H6B | 0.9800 | C15—H15 | 0.9500 |
C6—H6C | 0.9800 | C16—H16 | 0.9500 |
C7—O2 | 1.432 (2) | C17—O1 | 1.430 (2) |
C7—O3 | 1.444 (2) | C17—H17A | 0.9800 |
C7—C8 | 1.515 (3) | C17—H17B | 0.9800 |
C7—C9 | 1.520 (3) | C17—H17C | 0.9800 |
C8—H8A | 0.9800 | ||
O1—C1—O5 | 112.05 (13) | C7—C8—H8B | 109.5 |
O1—C1—C2 | 106.29 (14) | H8A—C8—H8B | 109.5 |
O5—C1—C2 | 113.32 (13) | C7—C8—H8C | 109.5 |
O1—C1—H1 | 108.3 | H8A—C8—H8C | 109.5 |
O5—C1—H1 | 108.3 | H8B—C8—H8C | 109.5 |
C2—C1—H1 | 108.3 | C7—C9—H9A | 109.5 |
O2—C2—C1 | 108.77 (14) | C7—C9—H9B | 109.5 |
O2—C2—C3 | 101.59 (13) | H9A—C9—H9B | 109.5 |
C1—C2—C3 | 116.31 (13) | C7—C9—H9C | 109.5 |
O2—C2—H2 | 109.9 | H9A—C9—H9C | 109.5 |
C1—C2—H2 | 109.9 | H9B—C9—H9C | 109.5 |
C3—C2—H2 | 109.9 | O10—C10—O4 | 123.43 (16) |
O3—C3—C4 | 110.40 (13) | O10—C10—C11 | 124.41 (16) |
O3—C3—C2 | 103.43 (13) | O4—C10—C11 | 112.16 (15) |
C4—C3—C2 | 112.55 (13) | C12—C11—C16 | 119.89 (16) |
O3—C3—H3 | 110.1 | C12—C11—C10 | 118.40 (16) |
C4—C3—H3 | 110.1 | C16—C11—C10 | 121.70 (15) |
C2—C3—H3 | 110.1 | C13—C12—C11 | 120.39 (17) |
O4—C4—C3 | 105.81 (13) | C13—C12—H12 | 119.8 |
O4—C4—C5 | 110.89 (13) | C11—C12—H12 | 119.8 |
C3—C4—C5 | 110.66 (13) | C12—C13—C14 | 119.56 (17) |
O4—C4—H4 | 109.8 | C12—C13—H13 | 120.2 |
C3—C4—H4 | 109.8 | C14—C13—H13 | 120.2 |
C5—C4—H4 | 109.8 | C15—C14—C13 | 120.14 (17) |
O5—C5—C6 | 106.53 (14) | C15—C14—H14 | 119.9 |
O5—C5—C4 | 105.96 (13) | C13—C14—H14 | 119.9 |
C6—C5—C4 | 113.48 (13) | C16—C15—C14 | 120.52 (18) |
O5—C5—H5 | 110.2 | C16—C15—H15 | 119.7 |
C6—C5—H5 | 110.2 | C14—C15—H15 | 119.7 |
C4—C5—H5 | 110.2 | C15—C16—C11 | 119.48 (16) |
C5—C6—H6A | 109.5 | C15—C16—H16 | 120.3 |
C5—C6—H6B | 109.5 | C11—C16—H16 | 120.3 |
H6A—C6—H6B | 109.5 | O1—C17—H17A | 109.5 |
C5—C6—H6C | 109.5 | O1—C17—H17B | 109.5 |
H6A—C6—H6C | 109.5 | H17A—C17—H17B | 109.5 |
H6B—C6—H6C | 109.5 | O1—C17—H17C | 109.5 |
O2—C7—O3 | 105.76 (13) | H17A—C17—H17C | 109.5 |
O2—C7—C8 | 108.31 (15) | H17B—C17—H17C | 109.5 |
O3—C7—C8 | 110.31 (15) | C1—O1—C17 | 111.89 (14) |
O2—C7—C9 | 110.83 (14) | C7—O2—C2 | 106.37 (13) |
O3—C7—C9 | 108.42 (15) | C3—O3—C7 | 108.68 (12) |
C8—C7—C9 | 112.97 (16) | C10—O4—C4 | 118.16 (14) |
C7—C8—H8A | 109.5 | C1—O5—C5 | 114.01 (13) |
O1—C1—C2—O2 | −157.19 (12) | C14—C15—C16—C11 | 0.5 (2) |
O5—C1—C2—O2 | 79.32 (16) | C12—C11—C16—C15 | −0.8 (2) |
O1—C1—C2—C3 | 88.94 (16) | C10—C11—C16—C15 | −179.90 (14) |
O5—C1—C2—C3 | −34.55 (19) | O5—C1—O1—C17 | −62.01 (17) |
O2—C2—C3—O3 | 33.42 (15) | C2—C1—O1—C17 | 173.71 (13) |
C1—C2—C3—O3 | 151.32 (14) | O3—C7—O2—C2 | 27.55 (16) |
O2—C2—C3—C4 | −85.74 (16) | C8—C7—O2—C2 | 145.80 (14) |
C1—C2—C3—C4 | 32.16 (19) | C9—C7—O2—C2 | −89.75 (17) |
O3—C3—C4—O4 | 78.25 (16) | C1—C2—O2—C7 | −160.68 (13) |
C2—C3—C4—O4 | −166.74 (12) | C3—C2—O2—C7 | −37.48 (15) |
O3—C3—C4—C5 | −161.57 (13) | C4—C3—O3—C7 | 103.04 (16) |
C2—C3—C4—C5 | −46.56 (18) | C2—C3—O3—C7 | −17.59 (16) |
O4—C4—C5—O5 | −179.86 (12) | O2—C7—O3—C3 | −5.03 (17) |
C3—C4—C5—O5 | 63.04 (17) | C8—C7—O3—C3 | −121.94 (16) |
O4—C4—C5—C6 | −63.31 (19) | C9—C7—O3—C3 | 113.87 (15) |
C3—C4—C5—C6 | 179.59 (13) | O10—C10—O4—C4 | −7.7 (2) |
O10—C10—C11—C12 | −6.5 (2) | C11—C10—O4—C4 | 171.77 (12) |
O4—C10—C11—C12 | 174.09 (13) | C3—C4—O4—C10 | −132.61 (14) |
O10—C10—C11—C16 | 172.67 (16) | C5—C4—O4—C10 | 107.36 (16) |
O4—C10—C11—C16 | −6.8 (2) | O1—C1—O5—C5 | −66.10 (17) |
C16—C11—C12—C13 | 0.4 (2) | C2—C1—O5—C5 | 54.17 (17) |
C10—C11—C12—C13 | 179.53 (15) | C6—C5—O5—C1 | 170.53 (13) |
C11—C12—C13—C14 | 0.3 (3) | C4—C5—O5—C1 | −68.33 (16) |
C12—C13—C14—C15 | −0.5 (3) | O10—C10—O4—C4 | −7.7 (2) |
C13—C14—C15—C16 | 0.1 (3) | C10—O4—C4—H4 | −14.2 |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O10i | 1.00 | 2.53 | 3.334 (4) | 137 |
C16—H16···O2i | 0.95 | 2.60 | 3.285 (4) | 129 |
C9—H9B···Cgii | 0.98 | 2.88 | 3.585 (4) | 130 |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C17H22O6 |
Mr | 322.35 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 100 |
a, b, c (Å) | 9.720 (8), 10.654 (11), 16.127 (14) |
V (Å3) | 1670 (3) |
Z | 4 |
Radiation type | Synchrotron, λ = 1.350 Å |
µ (mm−1) | 0.52 |
Crystal size (mm) | 0.15 × 0.10 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART 1K area-detector diffractometer |
Absorption correction | Part of the refinement model (ΔF) (SADABS; Sheldrick, 2002) |
Tmin, Tmax | 0.98, 1.00 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 18820, 2244, 2133 |
Rint | 0.095 |
(sin θ/λ)max (Å−1) | 0.662 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.088, 1.08 |
No. of reflections | 2244 |
No. of parameters | 212 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.26, −0.21 |
Computer programs: SMART (Bruker, 1998), SMART, SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Bergerhoff, 1996), PLATON (Spek, 2003).
O5—C1—C2—C3 | −34.55 (19) | C2—C1—O5—C5 | 54.17 (17) |
C1—C2—C3—C4 | 32.16 (19) | C4—C5—O5—C1 | −68.33 (16) |
C2—C3—C4—C5 | −46.56 (18) | O10—C10—O4—C4 | −7.7 (2) |
C3—C4—C5—O5 | 63.04 (17) | C10—O4—C4—H4 | −14.2 |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O10i | 1.00 | 2.53 | 3.334 (4) | 137 |
C16—H16···O2i | 0.95 | 2.60 | 3.285 (4) | 129 |
C9—H9B···Cgii | 0.98 | 2.88 | 3.585 (4) | 130 |
Symmetry codes: (i) −x+1, y+1/2, −z+1/2; (ii) x−1, y, z. |
H atom | δH 3JH,H+1 | C atom | δC |
H1 | 4.95(0.8) | C1 | 98.2 |
H2 | 4.19(5.5) | C2 | 76.1 |
H3 | 4.33(7.8) | C3 | 75.9 |
H4 | 5.12(10.1) | C4 | 75.1 |
H5 | 3.87(6.2) | C5 | 64.0 |
H6 | 1.23 | C6 | 17.2 |
C7 | 109.8 | ||
H8 | 1.62 | C8 | 27.8 |
H9 | 1.35 | C9 | 26.4 |
C10 | 165.8 | ||
C11 | 129.9 | ||
H12,H16 | 8.05 | C12,C16 | 129.8 |
H13,H15 | 7.44 | C13,C15 | 128.4 |
H14 | 7.56 | C14 | 133.2 |
H17 | 3.42 | C17 | 55.0 |
The title compound, (I), is an intermediate in the synthesis of rhamnopyranosyl oligosaccharides. The crystal structure of (I) is similar to that of another rhamnose derivative published some time ago (Eriksson et al., 1999). In the light of recent conformational analysis of acetyl esters of cyclic alcohols based on molecular mechanics calculations, NMR criteria and crystal structures (González-Outeiriño et al., 2005), it was of interest to analyze the conformation of the ester group in (I).
In the study by González-Outeiriño et al. (2005), it was concluded that acetyl ester groups without flanking equatorial groups prefer a staggered conformation, whereas when two flanking equatorial substituents were present an eclipsed conformation was preferred. For the θ1 torsion angle, corresponding to H4—C4—O4—C10 in (I), the syn conformation is the one that is usually observed, since the anti conformation was calculated to be at least 8 kJ mol−1 higher in energy. For the θ2 torsion angle, corresponding to C4—O4—C10—O10 in (I), analysis of the crystal structures revealed almost exclusive preference for a cis conformation, with only a few cases having a trans (anti-periplanar) conformation. Furthermore, a Karplus-type relationship was derived for use with NMR data, viz. 3JC,H = 3.1 cos2θ − 1.25 cosθ + 2.35 (Anderson, 2005).
For (I), the torsion angles are θ1 = −14.2° and θ2 = −7.7 (2)°. Thus, the conformation at the ester group can be described as eclipsed according to González-Outeiriño et al. (2005), with θ1 as syn and θ2 as cis.
To investigate the conformational preference of the θ1 torsion angle of the monosaccharide in solution, the 1H and 13C chemical shifts, as well as selected 3JH,H coupling constants, were determined by one- and two-dimensional NMR spectroscopy (Table 3). Heteronuclear 3JC,H coupling constants can be determined using an NMR technique based on selective excitation of 13C resonances and detection of the anti-phase multiplet pattern in the 1H NMR spectrum, using band-selective proton decoupling during the acquisition period if necessary (Nishida et al., 1996). Analysis of the NMR spectrum obtained with band-selective proton decoupling of the H5 resonance revealed JH4,C10 = 4.0 Hz. Employing the Karplus-type relationship, |θ1| = 17°, if interpreted as a single syn conformer. The θ1 torsion angle in (I) is therefore anticipated to have a similar conformation in solution to that in the crystal.
A few weak intermolecular hydrogen bonds are listed in Table 2. The phenyl rings are oriented in a pattern resembling the well known herringbone pattern (Desiraju & Steiner, 1999), as shown in Fig. 2, although it appears that close C—H···π contacts are absent in the title compound. The hexapyranose ring is somewhat distorted from a regular 1C4 chair conformation, with puckering parameters (Cremer & Pople, 1975) q2 = 0.226 (2) Å, q3 = −0.489 (2) Å, ϕ2 = 122.2 (4)°, Q = 0.538 (2) Å and θ = 155.2 (2) Å. The five-membered ring has an envelope conformation on C2, with puckering parameters q2 = 0.353 (2) Å and ϕ2 = 28.5 (2)°.