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The title 4,6-O-benzyl­idene-α-D-gluco­pyran­oside (systematic name: methyl 4-methoxy-2-oxo-8-phenyl-1,2,5a,6,9a,9b-hexa­hydro-4H,8H-7,9-dioxa­cyclo­penta­[c]­chromene-3-carboxyl­ate), C18H18O8, has been synthesized from the reaction of methyl 4,6-O-benzyl­idene-α-D-2-ketogluco­pyran­oside with diethyl or di­methyl malonate. The compound adopts a chair–chair conformation. The newly formed five-membered ring is fused to the gluco­pyran­oside ring along the C2—C3 bond and is planar with an r.m.s. deviation of 0.0091 Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101015505/da1200sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101015505/da1200Isup2.hkl
Contains datablock I

CCDC reference: 175117

Comment top

C-Branched monosaccharides are important chiral synthons in both organic chemistry and in biological substances, and some have been found as components of living cells (Adinolfi et al., 1995, 1996). The stereoselective addition of a nucleophile to a glycosidulose is an efficient route to the synthesis of C-branched sugars (Sato et al., 1994; Adinolfi et al., 2000). In these previous syntheses, the hydroxyl groups of the glycosiduloses have been fully protected, since unprotected and partially protected glycosiduloses have proven to be difficult to synthesize selectively, are unstable in basic medium and usually exist in different forms (Liu & Tsuda, 1993, 1996a). Thus, very little is known about the syntheses and structures of C-branched glucopyranosides made from partially protected 2-ketoglucosides. We report here the X-ray structure of (II), which was synthesized from the partially protected 2-ketoglucoside (I) by reaction with diethyl or dimethyl malonate in strong basic solution.

Compound (II) adopts a chair–chair conformation. Atoms C11 and C5 are displaced by -0.6769 (2) and 0.7023 (6) Å from the least-squares plane defined by atoms O4, O6, C4 and C6 (r.m.s. deviation 0.0022 Å), giving a flattened chair conformation. Atoms C2 and C5 deviate by -0.5444 (3) and 0.7216 (3) Å, respectively, from the plane defined by atoms C3, C4, C1 and O5 (r.m.s. deviation 0.0055 Å), resulting in a chair which is more distorted from a perfect chair conformation than the former, as can be expected from the different substitution pattern. The associated non-bonding distances are 2.786 (5) Å for C11,,,C5 and 2.763 (4) Å for C5,,,C2. The five-membered ring (C2, C3, C8, C18 and O3) is fused to the glucopyranoside ring along the C3—C2 bond in the equatorial position at C3. The short C2—C8 distance of 1.328 (5) Å is typical for a double bond having two carbonyl groups as neighbours, and the five-membered ring is consequently very planar, with an r.m.s. deviation of 0.0091 Å among the five atoms. Atom C3 exhibits the largest out-of-plane displacement of 0.0124 (2) Å, and C18 is closest to the mean plane [0.0028 (2) Å]. In addition, the phenyl ring is approximately parallel to the least-squares C6/C4/O4/O6 and C5/O5/C2/C3 planes, forming interplanar angles of 9.7 (2) and 5.3 (3)°, respectively. Similarly, the five-membered C2/C3/C8/C18/O3 ring is inclined at angles of 34.98 (9), 25.89 (8) and 29.82 (8)° to the C12–C17, C4/C6/O4/O6 and C2/C3/C5/O5 planes, respectively. The absolute structure was deduced based on compound (I), which is known to be an α-D-2-ketoglucopyranoside. As shown in the packing diagram (Fig. 2), the molecules stack along the b direction in an efficient manner.

Related literature top

For related literature, see: Adinolfi et al. (1995, 1996, 2000); Liu & Tsuda (1993, 1996a, 1996b); Sato et al. (1994).

Experimental top

The title compound was synthesized by the aldol condensation of compound (I) (400 mg, 1.43 mmol; Liu & Tsuda, 1996b) in CHCl3 with diethyl or dimethyl malonate (5.62 mmol) in the presence of sodium methoxide (516 mg, 9.56 mmol). The product (350 mg) was obtained as colourless crystals melting at 443–445 K after recrystallization from methanol/acetone.

Refinement top

All H atoms were fixed at ideal positions with a common isotropic displacement parameter (Uiso = 0.08 Å2).

Computing details top

Data collection: R-AXIS Software (Rigaku, 1997); cell refinement: R-AXIS Software; data reduction: R-AXIS Software; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TEXSAN (Molecular Structure Corporation, 1992); software used to prepare material for publication: TEXSAN.

Figures top
[Figure 1] Fig. 1. The molecular structure of (II) drawn with 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. Packing diagram viewed down the b axis.
(I) top
Crystal data top
C18H18O8Dx = 1.397 Mg m3
Mr = 362.32Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121Cell parameters from 188 reflections
a = 22.469 (5) Åθ = 2.8–26.0°
b = 4.6467 (9) ŵ = 0.11 mm1
c = 16.501 (3) ÅT = 291 K
V = 1722.8 (6) Å3Prism, colorless
Z = 40.30 × 0.30 × 0.20 mm
F(000) = 760
Data collection top
Rigaku R-AXIS-IV IP
diffractometer
2244 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.045
Graphite monochromatorθmax = 27.5°, θmin = 1.5°
Detector resolution: 100 pixels mm-1h = 029
Oscillation frames scansk = 66
2635 measured reflectionsl = 020
2608 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.054H-atom parameters not refined
wR(F2) = 0.103 w = 1/[σ2(Fo2) + (0.0456P)2 + 0.0022P]
where P = (Fo2 + 2Fc2)/3
S = 1.13(Δ/σ)max = 0.006
2608 reflectionsΔρmax = 0.17 e Å3
236 parametersΔρmin = 0.14 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0112 (11)
Crystal data top
C18H18O8V = 1722.8 (6) Å3
Mr = 362.32Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 22.469 (5) ŵ = 0.11 mm1
b = 4.6467 (9) ÅT = 291 K
c = 16.501 (3) Å0.30 × 0.30 × 0.20 mm
Data collection top
Rigaku R-AXIS-IV IP
diffractometer
2244 reflections with I > 2σ(I)
2635 measured reflectionsRint = 0.045
2608 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0540 restraints
wR(F2) = 0.103H-atom parameters not refined
S = 1.13Δρmax = 0.17 e Å3
2608 reflectionsΔρmin = 0.14 e Å3
236 parameters
Special details top

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
xyzUiso*/Ueq
O10.15952 (6)0.4688 (3)0.32087 (6)0.0498 (4)
O20.31517 (7)0.0894 (5)0.07470 (8)0.0791 (6)
O30.23100 (5)0.3476 (4)0.07963 (7)0.0557 (4)
O40.10271 (5)0.5107 (3)0.04932 (5)0.0393 (3)
O50.10115 (5)0.1443 (3)0.24604 (6)0.0410 (3)
O60.00484 (5)0.4733 (3)0.09490 (6)0.0436 (3)
O70.31436 (7)0.3078 (4)0.22505 (8)0.0711 (5)
O80.27567 (6)0.0519 (4)0.32712 (7)0.0607 (4)
C10.15797 (8)0.2072 (4)0.27957 (9)0.0389 (5)
H1A0.16990.05160.31620.047*
C20.20214 (8)0.2292 (4)0.21037 (8)0.0391 (5)
C30.18521 (8)0.4054 (5)0.13776 (9)0.0420 (5)
H3A0.18580.61010.15210.050*
C40.12355 (7)0.3216 (4)0.11118 (8)0.0366 (4)
H4A0.12370.12300.09110.044*
C50.08295 (8)0.3454 (4)0.18538 (9)0.0371 (4)
H5A0.08500.54110.20730.044*
C60.01979 (8)0.2799 (5)0.15934 (9)0.0440 (5)
H6A0.01680.08220.14090.053*
H6B0.00730.30610.20450.053*
C70.13260 (11)0.4512 (6)0.39997 (10)0.0705 (8)
H7A0.13730.63170.42750.106*
H7B0.15150.30160.43070.106*
H7C0.09100.40870.39440.106*
C80.25321 (8)0.0942 (4)0.19680 (9)0.0425 (5)
C90.28524 (8)0.1123 (5)0.24944 (10)0.0456 (5)
C100.29887 (11)0.2571 (6)0.38519 (13)0.0804 (8)
H10A0.29090.19040.43920.121*
H10B0.34110.27670.37780.121*
H10C0.28010.44040.37710.121*
C110.04338 (7)0.4382 (4)0.02755 (9)0.0381 (5)
H11A0.04200.23770.00920.046*
C120.02272 (8)0.6318 (4)0.03955 (9)0.0396 (5)
C130.03775 (9)0.6585 (6)0.05419 (10)0.0552 (6)
H13A0.06470.55840.02210.066*
C140.05827 (10)0.8321 (7)0.11589 (11)0.0683 (7)
H14A0.09900.85020.12490.082*
C150.01877 (10)0.9780 (6)0.16404 (10)0.0665 (7)
H15A0.03281.09750.20500.080*
C160.04172 (10)0.9485 (6)0.15192 (10)0.0578 (6)
H16A0.06851.04440.18540.069*
C170.06238 (9)0.7749 (5)0.08959 (9)0.0461 (5)
H17A0.10310.75440.08130.055*
C180.27312 (9)0.1657 (6)0.11221 (11)0.0524 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0637 (8)0.0490 (8)0.0367 (5)0.0051 (8)0.0023 (6)0.0055 (6)
O20.0533 (8)0.1257 (16)0.0582 (6)0.0181 (11)0.0180 (7)0.0163 (10)
O30.0397 (7)0.0855 (11)0.0421 (5)0.0016 (9)0.0034 (6)0.0185 (7)
O40.0361 (6)0.0450 (7)0.0367 (5)0.0006 (7)0.0030 (5)0.0078 (5)
O50.0400 (6)0.0398 (7)0.0432 (5)0.0055 (7)0.0008 (5)0.0077 (5)
O60.0387 (6)0.0491 (8)0.0430 (5)0.0079 (7)0.0036 (5)0.0010 (5)
O70.0637 (9)0.0732 (11)0.0762 (8)0.0200 (10)0.0085 (8)0.0125 (9)
O80.0665 (9)0.0702 (10)0.0456 (6)0.0046 (9)0.0106 (6)0.0135 (7)
C10.0405 (10)0.0395 (11)0.0366 (7)0.0002 (10)0.0013 (7)0.0056 (8)
C20.0417 (10)0.0406 (11)0.0351 (7)0.0081 (9)0.0060 (7)0.0047 (7)
C30.0353 (9)0.0491 (12)0.0417 (7)0.0045 (10)0.0025 (7)0.0061 (8)
C40.0358 (9)0.0365 (10)0.0376 (7)0.0006 (9)0.0009 (7)0.0028 (8)
C50.0414 (9)0.0340 (9)0.0358 (7)0.0012 (10)0.0023 (7)0.0011 (7)
C60.0434 (11)0.0455 (12)0.0432 (8)0.0011 (11)0.0016 (8)0.0072 (8)
C70.0855 (16)0.0828 (19)0.0433 (9)0.0026 (17)0.0112 (10)0.0102 (11)
C80.0352 (10)0.0525 (13)0.0399 (8)0.0051 (10)0.0017 (7)0.0041 (8)
C90.0364 (10)0.0527 (13)0.0478 (8)0.0048 (11)0.0023 (8)0.0029 (9)
C100.0827 (16)0.0913 (19)0.0670 (10)0.0067 (18)0.0229 (12)0.0327 (13)
C110.0359 (10)0.0362 (11)0.0424 (7)0.0013 (10)0.0007 (7)0.0046 (7)
C120.0454 (10)0.0384 (11)0.0350 (7)0.0053 (10)0.0058 (7)0.0080 (7)
C130.0457 (12)0.0695 (15)0.0504 (9)0.0021 (13)0.0055 (9)0.0011 (10)
C140.0545 (13)0.0925 (19)0.0579 (10)0.0126 (15)0.0150 (10)0.0034 (13)
C150.0786 (15)0.0732 (16)0.0476 (9)0.0125 (15)0.0193 (10)0.0051 (11)
C160.0729 (14)0.0590 (14)0.0414 (8)0.0022 (14)0.0065 (9)0.0062 (9)
C170.0490 (11)0.0464 (12)0.0430 (8)0.0026 (11)0.0026 (8)0.0033 (9)
C180.0383 (10)0.0758 (15)0.0430 (8)0.0019 (12)0.0022 (8)0.0079 (10)
Geometric parameters (Å, º) top
O1—C11.394 (2)C6—H6A0.9700
O1—C71.441 (2)C6—H6B0.9700
O2—C181.184 (2)C7—H7A0.9600
O3—C181.378 (3)C7—H7B0.9600
O3—C31.432 (2)C7—H7C0.9600
O4—C111.421 (2)C8—C91.481 (3)
O4—C41.426 (2)C8—C181.503 (2)
O5—C11.422 (2)C10—H10A0.9600
O5—C51.429 (2)C10—H10B0.9600
O6—C111.4185 (18)C10—H10C0.9600
O6—C61.432 (2)C11—C121.500 (2)
O7—C91.190 (3)C11—H11A0.9800
O8—C91.330 (2)C12—C171.385 (3)
O8—C101.449 (3)C12—C131.386 (3)
C1—C21.516 (2)C13—C141.378 (3)
C1—H1A0.9800C13—H13A0.9300
C2—C81.327 (3)C14—C151.371 (3)
C2—C31.500 (2)C14—H14A0.9300
C3—C41.505 (2)C15—C161.381 (3)
C3—H3A0.9800C15—H15A0.9300
C4—C51.531 (2)C16—C171.387 (3)
C4—H4A0.9800C16—H16A0.9300
C5—C61.514 (2)C17—H17A0.9300
C5—H5A0.9800
C1—O1—C7112.53 (16)O1—C7—H7C109.5
C18—O3—C3110.31 (13)H7A—C7—H7C109.5
C11—O4—C4110.05 (13)H7B—C7—H7C109.5
C1—O5—C5113.28 (13)C2—C8—C9128.87 (15)
C11—O6—C6111.48 (13)C2—C8—C18108.03 (16)
C9—O8—C10116.13 (18)C9—C8—C18122.92 (17)
O1—C1—O5113.08 (15)O7—C9—O8125.19 (18)
O1—C1—C2107.04 (15)O7—C9—C8124.29 (16)
O5—C1—C2107.97 (12)O8—C9—C8110.50 (17)
O1—C1—H1A109.6O8—C10—H10A109.5
O5—C1—H1A109.6O8—C10—H10B109.5
C2—C1—H1A109.6H10A—C10—H10B109.5
C8—C2—C3110.03 (14)O8—C10—H10C109.5
C8—C2—C1131.40 (16)H10A—C10—H10C109.5
C3—C2—C1118.18 (16)H10B—C10—H10C109.5
O3—C3—C2104.50 (15)O6—C11—O4110.33 (12)
O3—C3—C4114.69 (13)O6—C11—C12108.68 (14)
C2—C3—C4108.96 (15)O4—C11—C12109.55 (15)
O3—C3—H3A109.5O6—C11—H11A109.4
C2—C3—H3A109.5O4—C11—H11A109.4
C4—C3—H3A109.5C12—C11—H11A109.4
O4—C4—C3110.57 (15)C17—C12—C13118.94 (17)
O4—C4—C5109.41 (14)C17—C12—C11121.93 (16)
C3—C4—C5107.27 (12)C13—C12—C11119.07 (17)
O4—C4—H4A109.9C14—C13—C12120.6 (2)
C3—C4—H4A109.9C14—C13—H13A119.7
C5—C4—H4A109.9C12—C13—H13A119.7
O5—C5—C6109.61 (14)C15—C14—C13120.1 (2)
O5—C5—C4110.03 (14)C15—C14—H14A120.0
C6—C5—C4108.49 (13)C13—C14—H14A120.0
O5—C5—H5A109.6C14—C15—C16120.3 (2)
C6—C5—H5A109.6C14—C15—H15A119.9
C4—C5—H5A109.6C16—C15—H15A119.9
O6—C6—C5107.72 (15)C15—C16—C17119.6 (2)
O6—C6—H6A110.2C15—C16—H16A120.2
C5—C6—H6A110.2C17—C16—H16A120.2
O6—C6—H6B110.2C12—C17—C16120.40 (19)
C5—C6—H6B110.2C12—C17—H17A119.8
H6A—C6—H6B108.5C16—C17—H17A119.8
O1—C7—H7A109.5O2—C18—O3121.86 (17)
O1—C7—H7B109.5O2—C18—C8131.1 (2)
H7A—C7—H7B109.5O3—C18—C8107.07 (16)
C7—O1—C1—O577.34 (18)C3—C2—C8—C181.6 (2)
C7—O1—C1—C2163.89 (15)C1—C2—C8—C18170.92 (19)
C5—O5—C1—O163.63 (16)C10—O8—C9—O75.4 (3)
C5—O5—C1—C254.60 (19)C10—O8—C9—C8173.15 (17)
O1—C1—C2—C8112.9 (2)C2—C8—C9—O7147.1 (2)
O5—C1—C2—C8125.0 (2)C18—C8—C9—O727.5 (3)
O1—C1—C2—C375.05 (19)C2—C8—C9—O831.4 (3)
O5—C1—C2—C347.0 (2)C18—C8—C9—O8153.94 (19)
C18—O3—C3—C22.0 (2)C6—O6—C11—O463.75 (19)
C18—O3—C3—C4121.27 (18)C6—O6—C11—C12176.13 (15)
C8—C2—C3—O32.3 (2)C4—O4—C11—O662.38 (18)
C1—C2—C3—O3171.37 (16)C4—O4—C11—C12178.03 (13)
C8—C2—C3—C4125.29 (17)O6—C11—C12—C17142.21 (17)
C1—C2—C3—C448.3 (2)O4—C11—C12—C1721.6 (2)
C11—O4—C4—C3177.14 (14)O6—C11—C12—C1340.7 (2)
C11—O4—C4—C559.21 (18)O4—C11—C12—C13161.28 (17)
O3—C3—C4—O471.2 (2)C17—C12—C13—C142.1 (3)
C2—C3—C4—O4172.14 (14)C11—C12—C13—C14179.31 (19)
O3—C3—C4—C5169.61 (16)C12—C13—C14—C150.7 (4)
C2—C3—C4—C552.9 (2)C13—C14—C15—C161.1 (4)
C1—O5—C5—C6174.29 (14)C14—C15—C16—C171.4 (4)
C1—O5—C5—C466.49 (17)C13—C12—C17—C161.8 (3)
O4—C4—C5—O5176.50 (13)C11—C12—C17—C16178.91 (18)
C3—C4—C5—O563.5 (2)C15—C16—C17—C120.1 (3)
O4—C4—C5—C656.6 (2)C3—O3—C18—O2179.9 (2)
C3—C4—C5—C6176.58 (16)C3—O3—C18—C81.2 (2)
C11—O6—C6—C560.36 (18)C2—C8—C18—O2178.5 (3)
O5—C5—C6—O6176.17 (13)C9—C8—C18—O22.9 (4)
C4—C5—C6—O656.01 (19)C2—C8—C18—O30.3 (2)
C3—C2—C8—C9176.85 (19)C9—C8—C18—O3175.91 (17)
C1—C2—C8—C94.3 (3)

Experimental details

Crystal data
Chemical formulaC18H18O8
Mr362.32
Crystal system, space groupOrthorhombic, P212121
Temperature (K)291
a, b, c (Å)22.469 (5), 4.6467 (9), 16.501 (3)
V3)1722.8 (6)
Z4
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.30 × 0.30 × 0.20
Data collection
DiffractometerRigaku R-AXIS-IV IP
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2635, 2608, 2244
Rint0.045
(sin θ/λ)max1)0.651
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.054, 0.103, 1.13
No. of reflections2608
No. of parameters236
H-atom treatmentH-atom parameters not refined
Δρmax, Δρmin (e Å3)0.17, 0.14

Computer programs: R-AXIS Software (Rigaku, 1997), R-AXIS Software, SHELXS86 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), TEXSAN (Molecular Structure Corporation, 1992), TEXSAN.

 

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