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In the title compound, (2R,4R,5S,5aR)-rel-(-)-4-(1,3-benzodioxol-5-yl)-2,3,4,5-tetra­hydro-7-methoxy-5-methyl-8H-2,5a-methano-benzoepin-8-one, C20H20O5, the tetra­hydro­furan ring has an envelope conformation, and the semi­quinone ring is somewhat non-planar, with deviations from coplanarity of up to 0.1603 (13) Å.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801017482/ob6082sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801017482/ob6082Isup2.hkl
Contains datablock I

CCDC reference: 176030

Key indicators

  • Single-crystal X-ray study
  • T = 297 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.033
  • wR factor = 0.085
  • Data-to-parameter ratio = 7.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

REFLT_03 From the CIF: _diffrn_reflns_theta_max 74.90 From the CIF: _reflns_number_total 1748 Count of symmetry unique reflns 1704 Completeness (_total/calc) 102.58% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 44 Fraction of Friedel pairs measured 0.026 Are heavy atom types Z>Si present no WARNING: CuKa measured Friedel data can be used to determine absolute structure in a light-atom study only if the Friedel fraction is large.

Comment top

The title neolignan, (I), has been previously reported from Piper futokadsura (Ogiso et al., 1968), Magnolia denudata (Iida et al., 1982), Magnolia liliflora (Iida & Ito, 1983; Talapatra et al., 1982) and other plants (Shizuri & Yamamura, 1983). The crystal structure of an orthorhombic (P212121) polymorph has been previously reported (Roychowdhury & Gosh, 1984), but its coordinates are not available. The conformation of the molecule in the orthorhombic polymorph is reported by Roychowdhury & Gosh to be somewhat different from what we find, even in the portion of the molecule with three fused rings, which might be expected to be rather rigid. They report the tetrahydrofuran ring to be a half chair, while in the present trigonal polymorph, it is clearly envelope, with C7' lying 0.689 (3) Å out of the best plane of the other four atoms. Further, they report that all atoms of the semiquinone ring `except (the spiro C atom) lie on a plane since the torsion angles associated with this group are within 6° of zero'. We find larger deviations, with torsion angles about C3'—C4' and C4'—C5' differing from zero by 12.7 (3) and 19.8 (3)°, respectively. In the present structure, the six atoms of the semiquinone ring deviate from coplanarity by distances ranging from -0.0310 (14) Å for C3' to 0.1603 (13) Å for C1'. We find the C8—C1' bond to be somewhat elongated at 1.583 (2) Å, which was also noted by Roychowdhury & Gosh (1.589 Å).

In the title structure, a short intermolecular C4'···O2(y-x, 1 - x, z - 1/3) contact exists with a distance of 2.968 (3) Å.

Experimental top

Leaves of Magnolia soulangiana, collected in Vancouver, BC, Canada, were air-dried, ground, and extracted with CH2Cl2 at room temperature for 24 h. The crude extract was separated by standard vacuum liquid chromatography procedures (Cantrell et al., 1996), using silica gel and n-hexane/ethyl acetate mixtures of increasing polarity. Fractions 58–61 (of 66) yielded crystals of futoenone.

Refinement top

The absolute configuration could not be determined. H atoms were placed in calculated positions with C—H distances in the range 0.93–0.98 Å and thereafter treated as riding. A torsional parameter was refined for each methyl group; Uiso = 1.2Ueq of the attached atom (1.5 for methyl groups).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: maXus (Mackay et al., 1999); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The atom-numbering scheme for (I) with ellipsoids at the 40% probability level.
(2R,4R,5S,5aR)-rel-(-)-4-(1,3-benzodioxol-5-yl)-2,3,4,5- tetrahydro-7-methoxy-5-methyl-8H-2,5a-methano-benzoepin-8-one top
Crystal data top
C20H20O5Dx = 1.369 Mg m3
Mr = 340.36Cu Kα radiation, λ = 1.54180 Å
Trigonal, P31Cell parameters from 25 reflections
a = 7.5210 (6) Åθ = 23.5–42.6°
c = 25.2821 (13) ŵ = 0.81 mm1
V = 1238.50 (15) Å3T = 297 K
Z = 3Trigonal prism, colorless
F(000) = 5400.45 × 0.34 × 0.34 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
1727 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.044
Graphite monochromatorθmax = 74.9°, θmin = 5.2°
θ/2θ scansh = 99
Absorption correction: ψ scan
(North et al., 1968)
k = 99
Tmin = 0.614, Tmax = 0.724l = 031
4948 measured reflections3 standard reflections every 120 min
1748 independent reflections intensity decay: 1.0%
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)] = 0.033H-atom parameters constrained
wR(F2) = 0.085 w = 1/[σ2(Fo2) + (0.0526P)2 + 0.0948P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max < 0.001
1748 reflectionsΔρmax = 0.23 e Å3
229 parametersΔρmin = 0.17 e Å3
1 restraintExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0076 (11)
Crystal data top
C20H20O5Z = 3
Mr = 340.36Cu Kα radiation
Trigonal, P31µ = 0.81 mm1
a = 7.5210 (6) ÅT = 297 K
c = 25.2821 (13) Å0.45 × 0.34 × 0.34 mm
V = 1238.50 (15) Å3
Data collection top
Enraf-Nonius CAD-4
diffractometer
1727 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.044
Tmin = 0.614, Tmax = 0.7243 standard reflections every 120 min
4948 measured reflections intensity decay: 1.0%
1748 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0331 restraint
wR(F2) = 0.085H-atom parameters constrained
S = 1.10Δρmax = 0.23 e Å3
1748 reflectionsΔρmin = 0.17 e Å3
229 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
O11.1479 (2)0.8471 (3)0.50004 (7)0.0556 (4)
O21.0624 (3)0.7416 (3)0.58724 (7)0.0585 (5)
O30.0405 (2)0.3643 (3)0.39544 (6)0.0447 (4)
O40.0828 (3)0.2487 (3)0.31202 (9)0.0627 (5)
O50.1715 (3)0.0237 (3)0.23485 (7)0.0586 (5)
C10.5913 (3)0.5173 (3)0.47896 (7)0.0339 (4)
C20.7965 (3)0.6495 (3)0.46484 (7)0.0360 (4)
H20.83370.69030.42990.043*
C30.9402 (3)0.7163 (3)0.50433 (8)0.0371 (4)
C40.8881 (3)0.6548 (3)0.55644 (8)0.0406 (4)
C50.6907 (4)0.5273 (4)0.57151 (8)0.0443 (5)
H50.65620.48720.60660.053*
C60.5414 (3)0.4591 (3)0.53158 (8)0.0405 (4)
H60.40460.37220.54050.049*
C70.4204 (3)0.4515 (3)0.43851 (7)0.0332 (4)
H70.30090.32930.45300.040*
C80.4647 (3)0.3891 (3)0.38414 (7)0.0317 (4)
H80.59750.50080.37190.038*
C90.4833 (4)0.1974 (4)0.38983 (9)0.0458 (5)
H9A0.58520.22090.41600.069*
H9B0.52310.16650.35650.069*
H9C0.35340.08400.40050.069*
C101.2275 (4)0.8593 (5)0.55230 (11)0.0607 (7)
H10A1.32220.80710.55220.073*
H10B1.30131.00120.56390.073*
C110.2894 (4)0.1053 (5)0.19187 (10)0.0603 (7)
H11A0.25130.20790.18580.090*
H11B0.26310.02370.16050.090*
H11C0.43280.17080.20040.090*
C1'0.2961 (3)0.3639 (3)0.34259 (7)0.0322 (4)
C2'0.0864 (3)0.2419 (3)0.36637 (7)0.0359 (4)
C3'0.0398 (3)0.0420 (3)0.35842 (9)0.0444 (5)
H3'0.15830.02980.37860.053*
C4'0.0103 (3)0.0621 (3)0.31786 (9)0.0439 (5)
C5'0.1776 (3)0.0751 (3)0.28038 (8)0.0404 (4)
C6'0.3121 (3)0.2697 (3)0.29222 (7)0.0369 (4)
H6'0.41770.34810.26870.044*
C7'0.3057 (3)0.5726 (3)0.33730 (8)0.0401 (4)
H7'10.44570.68500.33390.048*
H7'20.22450.57450.30780.048*
C8'0.2118 (3)0.5766 (4)0.39009 (9)0.0425 (5)
H8'0.16290.67540.38990.051*
C9'0.3607 (4)0.6189 (4)0.43475 (8)0.0425 (5)
H9'10.29870.62530.46780.051*
H9'20.48320.75110.42920.051*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0400 (7)0.0791 (11)0.0386 (9)0.0229 (8)0.0077 (7)0.0096 (8)
O20.0596 (10)0.0853 (12)0.0309 (9)0.0364 (9)0.0199 (7)0.0184 (8)
O30.0414 (7)0.0673 (9)0.0283 (7)0.0294 (7)0.0021 (6)0.0008 (7)
O40.0682 (11)0.0391 (8)0.0628 (12)0.0132 (7)0.0149 (9)0.0062 (7)
O50.0782 (11)0.0523 (9)0.0327 (9)0.0231 (9)0.0089 (8)0.0164 (7)
C10.0410 (9)0.0439 (9)0.0172 (8)0.0215 (8)0.0002 (7)0.0029 (7)
C20.0413 (9)0.0500 (10)0.0160 (8)0.0224 (8)0.0003 (7)0.0008 (7)
C30.0394 (9)0.0480 (10)0.0258 (10)0.0234 (8)0.0024 (7)0.0072 (8)
C40.0532 (11)0.0560 (11)0.0214 (9)0.0338 (9)0.0119 (8)0.0141 (8)
C50.0612 (12)0.0594 (12)0.0148 (9)0.0320 (10)0.0023 (8)0.0037 (8)
C60.0448 (10)0.0524 (11)0.0186 (9)0.0200 (8)0.0023 (7)0.0027 (8)
C70.0362 (8)0.0471 (9)0.0162 (8)0.0208 (7)0.0005 (6)0.0026 (7)
C80.0335 (8)0.0417 (9)0.0164 (8)0.0162 (7)0.0003 (6)0.0039 (7)
C90.0547 (11)0.0564 (12)0.0353 (12)0.0346 (10)0.0098 (9)0.0097 (9)
C100.0530 (13)0.0927 (19)0.0395 (14)0.0388 (13)0.0171 (11)0.0310 (13)
C110.0661 (15)0.0802 (17)0.0251 (11)0.0295 (13)0.0038 (10)0.0183 (11)
C1'0.0365 (8)0.0386 (8)0.0151 (8)0.0140 (7)0.0001 (7)0.0003 (6)
C2'0.0367 (9)0.0518 (10)0.0176 (8)0.0209 (8)0.0013 (7)0.0045 (7)
C3'0.0373 (9)0.0525 (11)0.0301 (10)0.0126 (8)0.0008 (8)0.0133 (8)
C4'0.0447 (10)0.0405 (9)0.0348 (11)0.0124 (8)0.0133 (8)0.0052 (8)
C5'0.0517 (10)0.0432 (9)0.0217 (9)0.0203 (8)0.0079 (8)0.0040 (8)
C6'0.0443 (9)0.0428 (9)0.0151 (8)0.0154 (8)0.0013 (7)0.0004 (7)
C7'0.0508 (10)0.0433 (10)0.0222 (10)0.0205 (8)0.0025 (8)0.0027 (7)
C8'0.0510 (10)0.0538 (11)0.0316 (11)0.0329 (9)0.0030 (8)0.0022 (8)
C9'0.0536 (11)0.0582 (11)0.0241 (10)0.0341 (10)0.0044 (8)0.0105 (8)
Geometric parameters (Å, º) top
O1—C31.372 (3)C9—H9A0.9600
O1—C101.435 (3)C9—H9B0.9600
O2—C41.377 (3)C9—H9C0.9600
O2—C101.416 (4)C10—H10A0.9700
O3—C2'1.351 (3)C10—H10B0.9700
O3—C8'1.473 (3)C11—H11A0.9600
O4—C4'1.224 (3)C11—H11B0.9600
O5—C5'1.358 (3)C11—H11C0.9600
O5—C111.431 (3)C1'—C6'1.491 (2)
C1—C61.392 (3)C1'—C2'1.498 (2)
C1—C21.401 (3)C1'—C7'1.541 (3)
C1—C71.519 (2)C2'—C3'1.332 (3)
C2—C31.369 (3)C3'—C4'1.450 (3)
C2—H20.9300C3'—H3'0.9300
C3—C41.386 (3)C4'—C5'1.499 (3)
C4—C51.359 (3)C5'—C6'1.332 (3)
C5—C61.402 (3)C6'—H6'0.9300
C5—H50.9300C7'—C8'1.517 (3)
C6—H60.9300C7'—H7'10.9700
C7—C9'1.537 (3)C7'—H7'20.9700
C7—C81.542 (2)C8'—C9'1.508 (3)
C7—H70.9800C8'—H8'0.9800
C8—C91.523 (3)C9'—H9'10.9700
C8—C1'1.583 (2)C9'—H9'20.9700
C8—H80.9800
C3—O1—C10105.20 (19)O5—C11—H11A109.5
C4—O2—C10105.84 (19)O5—C11—H11B109.5
C2'—O3—C8'107.78 (15)H11A—C11—H11B109.5
C5'—O5—C11115.64 (19)O5—C11—H11C109.5
C6—C1—C2119.65 (18)H11A—C11—H11C109.5
C6—C1—C7119.34 (17)H11B—C11—H11C109.5
C2—C1—C7120.80 (17)C6'—C1'—C2'111.24 (15)
C3—C2—C1117.53 (17)C6'—C1'—C7'115.85 (16)
C3—C2—H2121.2C2'—C1'—C7'99.03 (15)
C1—C2—H2121.2C6'—C1'—C8111.95 (15)
C2—C3—O1127.76 (19)C2'—C1'—C8110.03 (14)
C2—C3—C4122.06 (18)C7'—C1'—C8107.97 (15)
O1—C3—C4110.18 (18)C3'—C2'—O3124.81 (19)
C5—C4—O2128.4 (2)C3'—C2'—C1'124.61 (19)
C5—C4—C3121.93 (18)O3—C2'—C1'110.54 (17)
O2—C4—C3109.6 (2)C2'—C3'—C4'119.05 (19)
C4—C5—C6116.67 (18)C2'—C3'—H3'120.5
C4—C5—H5121.7C4'—C3'—H3'120.5
C6—C5—H5121.7O4—C4'—C3'123.4 (2)
C1—C6—C5122.16 (19)O4—C4'—C5'121.0 (2)
C1—C6—H6118.9C3'—C4'—C5'115.52 (18)
C5—C6—H6118.9C6'—C5'—O5126.2 (2)
C1—C7—C9'108.71 (15)C6'—C5'—C4'121.93 (19)
C1—C7—C8115.04 (15)O5—C5'—C4'111.84 (18)
C9'—C7—C8112.98 (15)C5'—C6'—C1'121.12 (18)
C1—C7—H7106.5C5'—C6'—H6'119.4
C9'—C7—H7106.5C1'—C6'—H6'119.4
C8—C7—H7106.5C8'—C7'—C1'99.15 (16)
C9—C8—C7109.86 (16)C8'—C7'—H7'1111.9
C9—C8—C1'113.33 (15)C1'—C7'—H7'1111.9
C7—C8—C1'110.25 (14)C8'—C7'—H7'2111.9
C9—C8—H8107.7C1'—C7'—H7'2111.9
C7—C8—H8107.7H7'1—C7'—H7'2109.6
C1'—C8—H8107.7O3—C8'—C9'108.35 (18)
C8—C9—H9A109.5O3—C8'—C7'102.87 (17)
C8—C9—H9B109.5C9'—C8'—C7'111.03 (17)
H9A—C9—H9B109.5O3—C8'—H8'111.4
C8—C9—H9C109.5C9'—C8'—H8'111.4
H9A—C9—H9C109.5C7'—C8'—H8'111.4
H9B—C9—H9C109.5C8'—C9'—C7111.32 (16)
O2—C10—O1109.09 (19)C8'—C9'—H9'1109.4
O2—C10—H10A109.9C7—C9'—H9'1109.4
O1—C10—H10A109.9C8'—C9'—H9'2109.4
O2—C10—H10B109.9C7—C9'—H9'2109.4
O1—C10—H10B109.9H9'1—C9'—H9'2108.0
H10A—C10—H10B108.3
C6—C1—C2—C30.1 (3)C8'—O3—C2'—C1'3.3 (2)
C7—C1—C2—C3174.48 (18)C6'—C1'—C2'—C3'26.0 (3)
C1—C2—C3—O1179.1 (2)C7'—C1'—C2'—C3'148.33 (19)
C1—C2—C3—C40.9 (3)C8—C1'—C2'—C3'98.7 (2)
C10—O1—C3—C2177.6 (2)C6'—C1'—C2'—O3151.92 (16)
C10—O1—C3—C42.3 (2)C7'—C1'—C2'—O329.55 (19)
C10—O2—C4—C5179.4 (2)C8—C1'—C2'—O383.43 (18)
C10—O2—C4—C30.5 (2)O3—C2'—C3'—C4'167.15 (18)
C2—C3—C4—C51.2 (3)C1'—C2'—C3'—C4'10.4 (3)
O1—C3—C4—C5178.9 (2)C2'—C3'—C4'—O4171.1 (2)
C2—C3—C4—O2178.76 (19)C2'—C3'—C4'—C5'12.7 (3)
O1—C3—C4—O21.2 (2)C11—O5—C5'—C6'15.0 (3)
O2—C4—C5—C6179.4 (2)C11—O5—C5'—C4'164.9 (2)
C3—C4—C5—C60.5 (3)O4—C4'—C5'—C6'163.9 (2)
C2—C1—C6—C50.5 (3)C3'—C4'—C5'—C6'19.8 (3)
C7—C1—C6—C5175.19 (19)O4—C4'—C5'—O516.2 (3)
C4—C5—C6—C10.3 (3)C3'—C4'—C5'—O5160.10 (18)
C6—C1—C7—C9'91.1 (2)O5—C5'—C6'—C1'176.8 (2)
C2—C1—C7—C9'83.5 (2)C4'—C5'—C6'—C1'3.1 (3)
C6—C1—C7—C8141.08 (18)C2'—C1'—C6'—C5'18.2 (3)
C2—C1—C7—C844.3 (2)C7'—C1'—C6'—C5'130.2 (2)
C1—C7—C8—C964.9 (2)C8—C1'—C6'—C5'105.4 (2)
C9'—C7—C8—C9169.50 (17)C6'—C1'—C7'—C8'161.05 (16)
C1—C7—C8—C1'169.55 (15)C2'—C1'—C7'—C8'42.06 (18)
C9'—C7—C8—C1'43.9 (2)C8—C1'—C7'—C8'72.52 (17)
C4—O2—C10—O12.0 (3)C2'—O3—C8'—C9'92.49 (18)
C3—O1—C10—O22.6 (3)C2'—O3—C8'—C7'25.1 (2)
C9—C8—C1'—C6'46.7 (2)C1'—C7'—C8'—O341.81 (18)
C7—C8—C1'—C6'170.28 (15)C1'—C7'—C8'—C9'73.9 (2)
C9—C8—C1'—C2'77.6 (2)O3—C8'—C9'—C751.3 (2)
C7—C8—C1'—C2'46.0 (2)C7'—C8'—C9'—C760.9 (2)
C9—C8—C1'—C7'175.35 (17)C1—C7—C9'—C8'172.37 (18)
C7—C8—C1'—C7'61.04 (19)C8—C7—C9'—C8'43.4 (2)
C8'—O3—C2'—C3'174.57 (18)

Experimental details

Crystal data
Chemical formulaC20H20O5
Mr340.36
Crystal system, space groupTrigonal, P31
Temperature (K)297
a, c (Å)7.5210 (6), 25.2821 (13)
V3)1238.50 (15)
Z3
Radiation typeCu Kα
µ (mm1)0.81
Crystal size (mm)0.45 × 0.34 × 0.34
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.614, 0.724
No. of measured, independent and
observed [I > 2σ(I)] reflections
4948, 1748, 1727
Rint0.044
(sin θ/λ)max1)0.626
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.085, 1.10
No. of reflections1748
No. of parameters229
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.17

Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, maXus (Mackay et al., 1999), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
O1—C101.435 (3)O3—C8'1.473 (3)
O2—C101.416 (4)O4—C4'1.224 (3)
O3—C2'1.351 (3)C8—C1'1.583 (2)
C3—O1—C10105.20 (19)C2'—O3—C8'107.78 (15)
C4—O2—C10105.84 (19)
C2—C1—C7—C844.3 (2)C3'—C4'—C5'—C6'19.8 (3)
C8'—O3—C2'—C1'3.3 (2)C4'—C5'—C6'—C1'3.1 (3)
C6'—C1'—C2'—C3'26.0 (3)C2'—C1'—C6'—C5'18.2 (3)
C7'—C1'—C2'—O329.55 (19)C2'—C1'—C7'—C8'42.06 (18)
C1'—C2'—C3'—C4'10.4 (3)C2'—O3—C8'—C7'25.1 (2)
C2'—C3'—C4'—C5'12.7 (3)C1'—C7'—C8'—O341.81 (18)
 

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