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Acta Crystallogr Sect E Struct Rep Online. 2010 April 1; 66(Pt 4): o760.
Published online 2010 March 6. doi:  10.1107/S1600536810007920
PMCID: PMC2983991

16-O-Methyl­cafestol

Abstract

The title compound [systematic name: (3bS,5aS,7R,8R,10aR,10bS)-7-meth­oxy-10b-methyl-3b,4,5,6,7,8,9,10,10a,10b,11,12-dodeca­hydro-5a,8-methano-5aH-cyclo­hepta­l[5,6]naph­tho[2,1-b]furan-7-methanol], C21H30O3, was isolated from the beans of Coffea robusta. The mol­ecule contains five fused rings including a furan ring. The two six-membered rings are in chair conformations, but the third six-membered ring and the five-membered aliphatic ring adopt envelope conformations. Inter­molecular O—H(...)O hydrogen bonding is present in the crystal structure.

Related literature

For related structures, see: Beattie & Mills (1955 [triangle]); Djerassi et al. (1959 [triangle]); Finnegan & Djerassi (1960 [triangle]); Scott et al. (1962 [triangle]); Ducruix et al. (1977 [triangle]); Chakrabarti & Venkatesan (1981 [triangle]). For a total synthesis of cafestol, see: Corey et al. (1987 [triangle]). For the absolute configuration of a related compound, see: Djerassi et al. (1953 [triangle]). For the relative configuration, see: Scharnhop & Winterhalter (2009 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-0o760-scheme1.jpg

Experimental

Crystal data

  • C21H30O3
  • M r = 330.45
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o760-efi1.jpg
  • a = 10.6399 (9) Å
  • b = 7.0001 (5) Å
  • c = 11.5765 (12) Å
  • β = 92.640 (5)°
  • V = 861.31 (13) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 93 K
  • 0.50 × 0.33 × 0.20 mm

Data collection

  • Rigaku SPIDER diffractometer
  • 6921 measured reflections
  • 2116 independent reflections
  • 1961 reflections with I > 2σ(I)
  • R int = 0.029

Refinement

  • R[F 2 > 2σ(F 2)] = 0.031
  • wR(F 2) = 0.069
  • S = 1.00
  • 2116 reflections
  • 223 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.22 e Å−3
  • Δρmin = −0.15 e Å−3

Data collection: RAPID-AUTO (Rigaku, 2004 [triangle]); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810007920/xu2727sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810007920/xu2727Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors are grateful to the analytical staff of Chengdu Institute of Biology, CAS, for measuring the NMR spectra.

supplementary crystallographic information

Comment

Coffea robusta is a species of coffee which has its origins in western Africa. As a part of our research on the bioactive constituents in coffee, the title compound was isolated. Its relative configuration was obtained from ESI-MS and NMR analyses, which were compared with a recent report (Scharnhop et al., 2009), and confirmed by Single-crystal X-ray diffraction study. The molecule of the title compound contains a five-ring system A/B/C/D/E(Fig. 1). There is a trans junction between ring A(C1—C5/C10)and ring B(C5—C10). Cis junction are present between ring B and ring C(C8—C9/C11—C14) and ring C and ring D(C8/C13—C16). Ring A and D are both in envelope-like conformations, with C10 and C16 at the flap, respectively. Ring B and C both adopt chair conformations. The furan ring E(C5—C6/C18—C19/O1), of course, is planar. Intermolecular O—H···O hydrogen bonding helps to stabilize the crystal structure(Fig. 2).

Experimental

The powdered seeds of Coffea robusta were extracted with cyclohexane and filtered. The filtrate was evaporated under reduced pressure. Then the residue was hydrolyzed with KOH in EtOH and extracted with tert-Butyl methyl ether(TBME). The extract was chromatograhed over Silica gel column with eluent of petroleum ether/ethyl acetate(3:1) to provide the title compound as white solid. It was recrystallized in acetone to afford suitable crystals for Single-crystal X-ray diffraction analysis.

Refinement

Hydroxyl H atom was located in a difference Fourier map and was refined isotropically. Other H atoms were located geometrically with C—H = 0.95-1.00 Å, and were refined in riding mode with Uiso(H) = 1.2Ueq(C). The absolute configuration could not be determined from the X-ray analysis, owing to the absence of significant anomalous scattering, and Friedel pairs were merged. The absolute configuration was assigned by a comparison between the measured Optical Rotatory Power ([α]24D = -121° (c=0.4, CHCl3)) and a previous work (For Cafestol: [α]24D = -97° (CHCl3)) (Djerassi et al., 1953).

Figures

Fig. 1.
View of the title molecule showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
Fig. 2.
The crystal packing of the title molecule, viewed down the a axis. H atoms were omitted for clarity.

Crystal data

C21H30O3F(000) = 360
Mr = 330.45Dx = 1.274 Mg m3
Monoclinic, P21Melting point: 448 K
Hall symbol: P 2ybMo Kα radiation, λ = 0.71073 Å
a = 10.6399 (9) ÅCell parameters from 2892 reflections
b = 7.0001 (5) Åθ = 3.4–27.5°
c = 11.5765 (12) ŵ = 0.08 mm1
β = 92.640 (5)°T = 93 K
V = 861.31 (13) Å3Prism, colorless
Z = 20.50 × 0.33 × 0.20 mm

Data collection

Rigaku SPIDER diffractometer1961 reflections with I > 2σ(I)
Radiation source: Rotating AnodeRint = 0.029
graphiteθmax = 27.5°, θmin = 3.4°
ω scansh = −12→13
6921 measured reflectionsk = −9→9
2116 independent reflectionsl = −15→13

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.069H atoms treated by a mixture of independent and constrained refinement
S = 1.00w = 1/[σ2(Fo2) + (0.0309P)2 + 0.16P] where P = (Fo2 + 2Fc2)/3
2116 reflections(Δ/σ)max < 0.001
223 parametersΔρmax = 0.22 e Å3
1 restraintΔρmin = −0.15 e Å3

Special details

Experimental. 13C NMR (150 MHz, CDCl3, δ, p.p.m.): 148.8(C3), 140.6(C19), 120.1(C4), 108.3(C18), 87.0(C16), 60.5(C17), 52.1(C5), 49.1(C15), 48.9(C21), 44.4(C8), 44.3(C9), 41.5(C13), 41.0(C7), 38.7(C10), 37.8(C14), 35.8(C1), 25.7(C12), 23.1(C6), 20.6(C2), 19.2(C11), 13.3(C20).
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 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)

xyzUiso*/Ueq
O10.09240 (11)0.1142 (2)0.60603 (10)0.0202 (3)
O20.91263 (11)0.64850 (18)0.83888 (10)0.0180 (3)
O31.04079 (14)0.3897 (2)0.97682 (12)0.0259 (3)
C10.41584 (16)0.0015 (3)0.73392 (16)0.0173 (4)
H1A0.4554−0.05120.66510.021*
H1B0.4492−0.07050.80220.021*
C20.27216 (16)−0.0310 (3)0.72069 (16)0.0196 (4)
H2A0.2544−0.15770.68570.024*
H2B0.2349−0.02720.79750.024*
C30.21656 (16)0.1217 (3)0.64550 (14)0.0167 (4)
C40.27270 (16)0.2813 (3)0.60818 (14)0.0159 (4)
C50.41066 (16)0.3158 (3)0.63354 (15)0.0148 (4)
H50.45510.24950.57070.018*
C60.45291 (16)0.5236 (3)0.62997 (15)0.0174 (4)
H6A0.42380.59300.69830.021*
H6B0.41670.58650.55940.021*
C70.59643 (16)0.5269 (3)0.62984 (15)0.0175 (4)
H7A0.62540.66130.62790.021*
H7B0.62380.46320.55890.021*
C80.65845 (16)0.4275 (3)0.73580 (14)0.0148 (4)
C90.60201 (16)0.2259 (2)0.75520 (15)0.0141 (4)
H90.62910.14850.68810.017*
C100.45483 (16)0.2142 (3)0.74799 (15)0.0145 (4)
C110.66860 (16)0.1311 (3)0.86261 (14)0.0175 (4)
H11A0.61070.03500.89350.021*
H11B0.74330.06170.83670.021*
C120.71155 (17)0.2649 (3)0.96239 (15)0.0188 (4)
H12A0.64000.28541.01270.023*
H12B0.77930.20091.00940.023*
C130.75979 (16)0.4604 (3)0.92313 (15)0.0161 (4)
H130.78220.54360.99120.019*
C140.65661 (17)0.5522 (3)0.84587 (15)0.0167 (4)
H14A0.67650.68720.82880.020*
H14B0.57400.54570.88170.020*
C150.80304 (16)0.4041 (3)0.72158 (14)0.0166 (4)
H15A0.82270.27160.69860.020*
H15B0.83190.49230.66140.020*
C160.86878 (16)0.4516 (3)0.84003 (15)0.0159 (4)
C170.97698 (17)0.3184 (3)0.87504 (15)0.0198 (4)
H17A0.94410.18870.88970.024*
H17B1.03620.30990.81170.024*
C180.17903 (17)0.3819 (3)0.53822 (16)0.0201 (4)
H180.18970.49900.49830.024*
C190.07310 (17)0.2766 (3)0.54064 (16)0.0213 (4)
H19−0.00460.31010.50230.026*
C200.39111 (16)0.2962 (3)0.85393 (15)0.0181 (4)
H20A0.42780.23710.92440.022*
H20B0.30070.26900.84750.022*
H20C0.40430.43470.85730.022*
C211.01924 (17)0.6855 (3)0.77196 (17)0.0233 (4)
H21A1.00820.62170.69680.028*
H21B1.09530.63680.81290.028*
H21C1.02750.82350.76010.028*
H3O1.052 (2)0.302 (4)1.021 (2)0.043 (8)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0154 (6)0.0215 (7)0.0235 (7)−0.0012 (6)−0.0020 (5)−0.0019 (6)
O20.0194 (6)0.0162 (7)0.0184 (6)−0.0047 (5)0.0000 (5)0.0010 (5)
O30.0326 (8)0.0219 (8)0.0221 (7)−0.0020 (6)−0.0116 (6)0.0034 (6)
C10.0173 (9)0.0132 (9)0.0210 (9)−0.0003 (7)−0.0024 (7)0.0013 (7)
C20.0195 (9)0.0148 (9)0.0245 (10)−0.0037 (7)−0.0004 (7)0.0005 (7)
C30.0129 (8)0.0196 (9)0.0172 (8)−0.0006 (8)−0.0015 (6)−0.0029 (8)
C40.0178 (9)0.0166 (9)0.0135 (8)0.0014 (7)0.0009 (6)−0.0031 (7)
C50.0152 (8)0.0135 (9)0.0157 (8)−0.0008 (7)0.0002 (6)−0.0001 (7)
C60.0190 (9)0.0149 (9)0.0181 (9)−0.0007 (7)−0.0007 (7)0.0046 (7)
C70.0180 (9)0.0169 (9)0.0174 (9)−0.0043 (7)−0.0002 (7)0.0034 (7)
C80.0156 (8)0.0135 (8)0.0154 (8)−0.0015 (7)0.0008 (6)0.0010 (7)
C90.0145 (8)0.0129 (8)0.0148 (9)−0.0011 (7)0.0007 (6)−0.0016 (7)
C100.0156 (8)0.0123 (8)0.0154 (9)−0.0008 (7)−0.0009 (7)0.0012 (7)
C110.0181 (9)0.0138 (8)0.0204 (9)−0.0018 (8)−0.0016 (7)0.0021 (8)
C120.0204 (9)0.0207 (10)0.0152 (9)−0.0047 (8)−0.0016 (7)0.0031 (8)
C130.0187 (9)0.0160 (9)0.0135 (8)−0.0038 (7)0.0007 (7)−0.0025 (7)
C140.0170 (9)0.0132 (8)0.0199 (9)−0.0024 (7)0.0018 (7)−0.0026 (7)
C150.0164 (8)0.0181 (9)0.0155 (8)−0.0021 (7)0.0014 (6)−0.0003 (7)
C160.0168 (9)0.0133 (9)0.0176 (9)−0.0038 (7)−0.0011 (7)−0.0005 (7)
C170.0199 (9)0.0204 (10)0.0189 (9)−0.0016 (8)−0.0030 (7)−0.0015 (8)
C180.0207 (9)0.0206 (10)0.0190 (9)0.0023 (8)−0.0006 (7)−0.0002 (8)
C190.0182 (9)0.0253 (10)0.0201 (9)0.0035 (8)−0.0024 (7)0.0001 (8)
C200.0167 (8)0.0204 (9)0.0171 (9)−0.0037 (8)0.0007 (7)0.0000 (8)
C210.0212 (9)0.0271 (11)0.0215 (10)−0.0078 (8)0.0002 (7)0.0039 (8)

Geometric parameters (Å, °)

O1—C191.376 (2)C9—C101.566 (2)
O1—C31.379 (2)C9—H91.0000
O2—C211.427 (2)C10—C201.539 (2)
O2—C161.455 (2)C11—C121.540 (2)
O3—C171.423 (2)C11—H11A0.9900
O3—H3O0.81 (3)C11—H11B0.9900
C1—C21.546 (2)C12—C131.538 (3)
C1—C101.552 (2)C12—H12A0.9900
C1—H1A0.9900C12—H12B0.9900
C1—H1B0.9900C13—C141.526 (3)
C2—C31.484 (3)C13—C161.542 (2)
C2—H2A0.9900C13—H131.0000
C2—H2B0.9900C14—H14A0.9900
C3—C41.347 (3)C14—H14B0.9900
C4—C181.439 (2)C15—C161.547 (2)
C4—C51.503 (2)C15—H15A0.9900
C5—C61.524 (3)C15—H15B0.9900
C5—C101.557 (2)C16—C171.522 (3)
C5—H51.0000C17—H17A0.9900
C6—C71.527 (2)C17—H17B0.9900
C6—H6A0.9900C18—C191.348 (3)
C6—H6B0.9900C18—H180.9500
C7—C81.533 (2)C19—H190.9500
C7—H7A0.9900C20—H20A0.9800
C7—H7B0.9900C20—H20B0.9800
C8—C141.546 (2)C20—H20C0.9800
C8—C91.554 (2)C21—H21A0.9800
C8—C151.563 (2)C21—H21B0.9800
C9—C111.552 (2)C21—H21C0.9800
C19—O1—C3105.49 (14)C9—C11—H11A108.1
C21—O2—C16116.12 (14)C12—C11—H11B108.1
C17—O3—H3O107.8 (19)C9—C11—H11B108.1
C2—C1—C10114.20 (14)H11A—C11—H11B107.3
C2—C1—H1A108.7C13—C12—C11114.28 (14)
C10—C1—H1A108.7C13—C12—H12A108.7
C2—C1—H1B108.7C11—C12—H12A108.7
C10—C1—H1B108.7C13—C12—H12B108.7
H1A—C1—H1B107.6C11—C12—H12B108.7
C3—C2—C1108.51 (15)H12A—C12—H12B107.6
C3—C2—H2A110.0C14—C13—C12107.89 (15)
C1—C2—H2A110.0C14—C13—C16101.10 (14)
C3—C2—H2B110.0C12—C13—C16114.82 (15)
C1—C2—H2B110.0C14—C13—H13110.9
H2A—C2—H2B108.4C12—C13—H13110.9
C4—C3—O1110.95 (16)C16—C13—H13110.9
C4—C3—C2127.93 (15)C13—C14—C8102.08 (14)
O1—C3—C2121.11 (16)C13—C14—H14A111.4
C3—C4—C18106.28 (15)C8—C14—H14A111.4
C3—C4—C5120.92 (16)C13—C14—H14B111.4
C18—C4—C5132.55 (17)C8—C14—H14B111.4
C4—C5—C6115.76 (15)H14A—C14—H14B109.2
C4—C5—C10110.29 (14)C16—C15—C8106.93 (13)
C6—C5—C10112.40 (14)C16—C15—H15A110.3
C4—C5—H5105.9C8—C15—H15A110.3
C6—C5—H5105.9C16—C15—H15B110.3
C10—C5—H5105.9C8—C15—H15B110.3
C5—C6—C7108.12 (15)H15A—C15—H15B108.6
C5—C6—H6A110.1O2—C16—C17110.11 (14)
C7—C6—H6A110.1O2—C16—C13102.62 (14)
C5—C6—H6B110.1C17—C16—C13116.09 (15)
C7—C6—H6B110.1O2—C16—C15109.12 (14)
H6A—C6—H6B108.4C17—C16—C15114.21 (15)
C6—C7—C8112.69 (14)C13—C16—C15103.85 (14)
C6—C7—H7A109.1O3—C17—C16109.38 (16)
C8—C7—H7A109.1O3—C17—H17A109.8
C6—C7—H7B109.1C16—C17—H17A109.8
C8—C7—H7B109.1O3—C17—H17B109.8
H7A—C7—H7B107.8C16—C17—H17B109.8
C7—C8—C14112.44 (15)H17A—C17—H17B108.2
C7—C8—C9111.91 (14)C19—C18—C4106.20 (17)
C14—C8—C9111.97 (14)C19—C18—H18126.9
C7—C8—C15110.65 (13)C4—C18—H18126.9
C14—C8—C15101.29 (13)C18—C19—O1111.06 (16)
C9—C8—C15108.00 (14)C18—C19—H19124.5
C11—C9—C8109.82 (14)O1—C19—H19124.5
C11—C9—C10116.03 (14)C10—C20—H20A109.5
C8—C9—C10115.59 (14)C10—C20—H20B109.5
C11—C9—H9104.7H20A—C20—H20B109.5
C8—C9—H9104.7C10—C20—H20C109.5
C10—C9—H9104.7H20A—C20—H20C109.5
C20—C10—C1108.40 (15)H20B—C20—H20C109.5
C20—C10—C5112.40 (14)O2—C21—H21A109.5
C1—C10—C5106.25 (14)O2—C21—H21B109.5
C20—C10—C9114.45 (14)H21A—C21—H21B109.5
C1—C10—C9108.50 (14)O2—C21—H21C109.5
C5—C10—C9106.46 (14)H21A—C21—H21C109.5
C12—C11—C9116.73 (16)H21B—C21—H21C109.5
C12—C11—H11A108.1
C10—C1—C2—C340.0 (2)C11—C9—C10—C1−65.34 (19)
C19—O1—C3—C40.62 (19)C8—C9—C10—C1163.96 (14)
C19—O1—C3—C2179.58 (16)C11—C9—C10—C5−179.33 (14)
C1—C2—C3—C4−10.1 (3)C8—C9—C10—C549.96 (19)
C1—C2—C3—O1171.15 (15)C8—C9—C11—C1233.6 (2)
O1—C3—C4—C18−1.1 (2)C10—C9—C11—C12−99.74 (18)
C2—C3—C4—C18−179.94 (18)C9—C11—C12—C13−36.3 (2)
O1—C3—C4—C5−176.03 (15)C11—C12—C13—C1455.56 (19)
C2—C3—C4—C55.1 (3)C11—C12—C13—C16−56.3 (2)
C3—C4—C5—C6−157.29 (16)C12—C13—C14—C8−70.78 (16)
C18—C4—C5—C629.3 (3)C16—C13—C14—C850.07 (16)
C3—C4—C5—C10−28.3 (2)C7—C8—C14—C13−160.51 (14)
C18—C4—C5—C10158.29 (18)C9—C8—C14—C1372.48 (16)
C4—C5—C6—C7−167.16 (13)C15—C8—C14—C13−42.38 (16)
C10—C5—C6—C764.86 (18)C7—C8—C15—C16138.40 (15)
C5—C6—C7—C8−58.46 (19)C14—C8—C15—C1618.98 (18)
C6—C7—C8—C14−77.13 (19)C9—C8—C15—C16−98.79 (16)
C6—C7—C8—C949.9 (2)C21—O2—C16—C1753.11 (19)
C6—C7—C8—C15170.41 (15)C21—O2—C16—C13177.30 (14)
C7—C8—C9—C11179.55 (14)C21—O2—C16—C15−72.99 (18)
C14—C8—C9—C11−53.16 (18)C14—C13—C16—O276.47 (16)
C15—C8—C9—C1157.52 (17)C12—C13—C16—O2−167.70 (14)
C7—C8—C9—C10−46.8 (2)C14—C13—C16—C17−163.39 (15)
C14—C8—C9—C1080.45 (18)C12—C13—C16—C17−47.6 (2)
C15—C8—C9—C10−168.87 (14)C14—C13—C16—C15−37.17 (17)
C2—C1—C10—C2057.47 (19)C12—C13—C16—C1578.65 (18)
C2—C1—C10—C5−63.55 (19)C8—C15—C16—O2−97.88 (16)
C2—C1—C10—C9−177.68 (14)C8—C15—C16—C17138.41 (16)
C4—C5—C10—C20−64.11 (19)C8—C15—C16—C1311.01 (19)
C6—C5—C10—C2066.70 (18)O2—C16—C17—O349.13 (19)
C4—C5—C10—C154.31 (18)C13—C16—C17—O3−66.9 (2)
C6—C5—C10—C1−174.88 (14)C15—C16—C17—O3172.30 (15)
C4—C5—C10—C9169.83 (14)C3—C4—C18—C191.1 (2)
C6—C5—C10—C9−59.36 (18)C5—C4—C18—C19175.23 (18)
C11—C9—C10—C2055.9 (2)C4—C18—C19—O1−0.8 (2)
C8—C9—C10—C20−74.85 (19)C3—O1—C19—C180.1 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O3—H3O···O2i0.81 (3)1.97 (3)2.7479 (19)163 (3)

Symmetry codes: (i) −x+2, y−1/2, −z+2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU2727).

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