Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801017779/om6065sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801017779/om6065Isup2.hkl |
CCDC reference: 176035
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 63–66 (of 66) yielded crystals of denudatin A.
The absolute configuration could not be determined. H atoms were placed in calculated positions with C—H bond distances in the range 0.95–1.00 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).
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.
C20H20O5 | F(000) = 720 |
Mr = 340.36 | Dx = 1.315 Mg m−3 |
Monoclinic, C2 | Mo Kα radiation, λ = 0.71073 Å |
a = 17.8678 (17) Å | Cell parameters from 25 reflections |
b = 6.7905 (18) Å | θ = 10.2–23.4° |
c = 16.382 (2) Å | µ = 0.09 mm−1 |
β = 120.114 (10)° | T = 100 K |
V = 1719.4 (5) Å3 | Needle, colorless |
Z = 4 | 0.45 × 0.20 × 0.15 mm |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.056 |
Radiation source: fine-focus sealed tube | θmax = 30.0°, θmin = 1.4° |
Graphite monochromator | h = −24→21 |
θ/2θ scans | k = 0→9 |
3590 measured reflections | l = −19→21 |
2619 independent reflections | 3 standard reflections every 120 min |
1813 reflections with I > 2σ(I) | intensity decay: <1% |
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)] = 0.061 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.166 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0922P)2 + 0.03P] where P = (Fo2 + 2Fc2)/3 |
2619 reflections | (Δ/σ)max < 0.001 |
228 parameters | Δρmax = 0.42 e Å−3 |
1 restraint | Δρmin = −0.23 e Å−3 |
C20H20O5 | V = 1719.4 (5) Å3 |
Mr = 340.36 | Z = 4 |
Monoclinic, C2 | Mo Kα radiation |
a = 17.8678 (17) Å | µ = 0.09 mm−1 |
b = 6.7905 (18) Å | T = 100 K |
c = 16.382 (2) Å | 0.45 × 0.20 × 0.15 mm |
β = 120.114 (10)° |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.056 |
3590 measured reflections | 3 standard reflections every 120 min |
2619 independent reflections | intensity decay: <1% |
1813 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.061 | 1 restraint |
wR(F2) = 0.166 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.42 e Å−3 |
2619 reflections | Δρmin = −0.23 e Å−3 |
228 parameters |
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 | ||
O1 | 0.67641 (18) | 0.0531 (5) | 0.6518 (2) | 0.0387 (7) | |
O2 | 0.80453 (17) | 0.2200 (4) | 0.74401 (18) | 0.0337 (6) | |
O3 | 0.28018 (19) | 0.1076 (5) | 0.0946 (2) | 0.0406 (7) | |
O4 | 0.55930 (16) | 0.3352 (4) | 0.31577 (17) | 0.0310 (6) | |
C1 | 0.6435 (2) | 0.4419 (6) | 0.4791 (3) | 0.0249 (7) | |
C2 | 0.6220 (2) | 0.2735 (5) | 0.5134 (3) | 0.0271 (8) | |
H2 | 0.5693 | 0.2046 | 0.4761 | 0.032* | |
C3 | 0.6807 (2) | 0.2143 (6) | 0.6026 (3) | 0.0279 (8) | |
C4 | 0.7574 (2) | 0.3153 (6) | 0.6584 (2) | 0.0277 (8) | |
C5 | 0.7785 (2) | 0.4829 (6) | 0.6281 (3) | 0.0313 (8) | |
H5 | 0.8302 | 0.5539 | 0.6673 | 0.038* | |
C6 | 0.7196 (2) | 0.5441 (6) | 0.5359 (3) | 0.0302 (8) | |
H6 | 0.7322 | 0.6585 | 0.5116 | 0.036* | |
C7 | 0.5849 (2) | 0.5086 (5) | 0.3790 (2) | 0.0256 (8) | |
H7 | 0.6172 | 0.6030 | 0.3610 | 0.031* | |
C8 | 0.4983 (2) | 0.6023 (5) | 0.3569 (3) | 0.0268 (8) | |
H8 | 0.4732 | 0.5266 | 0.3899 | 0.032* | |
C9 | 0.5092 (2) | 0.8178 (6) | 0.3876 (3) | 0.0317 (9) | |
H9A | 0.5476 | 0.8262 | 0.4561 | 0.048* | |
H9B | 0.4526 | 0.8736 | 0.3706 | 0.048* | |
H9C | 0.5344 | 0.8919 | 0.3559 | 0.048* | |
C10 | 0.7626 (3) | 0.0321 (6) | 0.7303 (3) | 0.0359 (9) | |
H10A | 0.7943 | −0.0705 | 0.7169 | 0.043* | |
H10B | 0.7609 | −0.0063 | 0.7877 | 0.043* | |
C1' | 0.2958 (2) | 0.4395 (6) | 0.1448 (3) | 0.0285 (8) | |
C2' | 0.3308 (3) | 0.2401 (6) | 0.1414 (3) | 0.0306 (8) | |
C3' | 0.4236 (3) | 0.2069 (6) | 0.1969 (3) | 0.0318 (8) | |
H3' | 0.4475 | 0.0830 | 0.1953 | 0.038* | |
C4' | 0.4741 (2) | 0.3518 (6) | 0.2497 (3) | 0.0273 (8) | |
O5 | 0.47960 (16) | 0.6938 (4) | 0.20825 (18) | 0.0320 (6) | |
C5' | 0.4452 (2) | 0.5614 (5) | 0.2505 (3) | 0.0261 (8) | |
C6' | 0.3485 (2) | 0.5819 (6) | 0.1995 (2) | 0.0279 (8) | |
H6' | 0.3240 | 0.7006 | 0.2063 | 0.033* | |
C7' | 0.1989 (2) | 0.4613 (6) | 0.0821 (3) | 0.0335 (9) | |
H7'1 | 0.1830 | 0.4228 | 0.0171 | 0.040* | |
H7'2 | 0.1700 | 0.3684 | 0.1041 | 0.040* | |
C8' | 0.1649 (2) | 0.6641 (7) | 0.0795 (3) | 0.0421 (11) | |
H8' | 0.1893 | 0.7707 | 0.0632 | 0.050* | |
C9' | 0.1032 (3) | 0.7030 (11) | 0.0983 (4) | 0.073 (2) | |
H9'1 | 0.0775 | 0.5994 | 0.1148 | 0.088* | |
H9'2 | 0.0842 | 0.8348 | 0.0955 | 0.088* | |
C10' | 0.4577 (3) | 0.6498 (7) | 0.1140 (3) | 0.0400 (10) | |
H10C | 0.4817 | 0.5210 | 0.1122 | 0.060* | |
H10D | 0.4819 | 0.7511 | 0.0911 | 0.060* | |
H10E | 0.3947 | 0.6469 | 0.0736 | 0.060* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0362 (14) | 0.0289 (15) | 0.0473 (16) | −0.0063 (12) | 0.0182 (12) | 0.0093 (13) |
O2 | 0.0352 (13) | 0.0239 (14) | 0.0369 (14) | 0.0001 (12) | 0.0142 (11) | 0.0026 (12) |
O3 | 0.0524 (17) | 0.0230 (15) | 0.0442 (16) | −0.0073 (13) | 0.0226 (14) | −0.0067 (13) |
O4 | 0.0297 (12) | 0.0192 (13) | 0.0378 (13) | 0.0088 (11) | 0.0122 (10) | −0.0019 (12) |
C1 | 0.0233 (15) | 0.0163 (16) | 0.0358 (18) | 0.0035 (13) | 0.0154 (14) | 0.0007 (15) |
C2 | 0.0251 (16) | 0.0171 (17) | 0.0389 (19) | −0.0036 (14) | 0.0160 (14) | −0.0009 (14) |
C3 | 0.0333 (18) | 0.0134 (15) | 0.0418 (19) | 0.0001 (15) | 0.0225 (15) | 0.0009 (15) |
C4 | 0.0278 (17) | 0.0249 (19) | 0.0315 (17) | 0.0006 (16) | 0.0156 (14) | −0.0039 (16) |
C5 | 0.0278 (17) | 0.0200 (18) | 0.041 (2) | −0.0059 (14) | 0.0136 (15) | −0.0061 (16) |
C6 | 0.0291 (17) | 0.0177 (17) | 0.043 (2) | −0.0010 (14) | 0.0172 (15) | 0.0021 (16) |
C7 | 0.0248 (15) | 0.0156 (16) | 0.0337 (18) | 0.0022 (13) | 0.0126 (14) | 0.0006 (14) |
C8 | 0.0248 (16) | 0.0148 (17) | 0.0376 (19) | 0.0018 (14) | 0.0132 (14) | −0.0014 (15) |
C9 | 0.0282 (17) | 0.0156 (17) | 0.041 (2) | 0.0023 (15) | 0.0100 (15) | −0.0052 (16) |
C10 | 0.039 (2) | 0.025 (2) | 0.045 (2) | 0.0046 (17) | 0.0211 (17) | 0.0072 (17) |
C1' | 0.0285 (17) | 0.0226 (18) | 0.0314 (18) | −0.0022 (15) | 0.0128 (14) | −0.0019 (16) |
C2' | 0.042 (2) | 0.0199 (18) | 0.0294 (18) | −0.0024 (16) | 0.0172 (15) | −0.0027 (15) |
C3' | 0.042 (2) | 0.0174 (17) | 0.0347 (19) | 0.0046 (16) | 0.0180 (16) | −0.0016 (15) |
C4' | 0.0331 (18) | 0.0164 (17) | 0.0353 (18) | 0.0059 (14) | 0.0193 (15) | 0.0035 (15) |
O5 | 0.0311 (13) | 0.0211 (14) | 0.0399 (14) | −0.0010 (11) | 0.0149 (11) | 0.0040 (12) |
C5' | 0.0260 (15) | 0.0143 (16) | 0.0341 (18) | −0.0001 (13) | 0.0122 (14) | −0.0020 (14) |
C6' | 0.0259 (16) | 0.0208 (18) | 0.0317 (17) | 0.0025 (15) | 0.0105 (14) | −0.0021 (15) |
C7' | 0.0320 (19) | 0.029 (2) | 0.0322 (19) | −0.0078 (16) | 0.0105 (15) | −0.0022 (17) |
C8' | 0.0254 (18) | 0.038 (3) | 0.043 (2) | 0.0015 (17) | 0.0030 (16) | −0.0118 (19) |
C9' | 0.035 (2) | 0.083 (5) | 0.079 (4) | 0.004 (3) | 0.012 (2) | −0.038 (4) |
C10' | 0.040 (2) | 0.038 (2) | 0.042 (2) | 0.0111 (19) | 0.0208 (17) | 0.0122 (19) |
O1—C3 | 1.384 (5) | C9—H9C | 0.9800 |
O1—C10 | 1.435 (5) | C10—H10A | 0.9900 |
O2—C4 | 1.382 (4) | C10—H10B | 0.9900 |
O2—C10 | 1.439 (5) | C1'—C6' | 1.333 (5) |
O3—C2' | 1.233 (5) | C1'—C2' | 1.505 (5) |
O4—C4' | 1.359 (4) | C1'—C7' | 1.512 (5) |
O4—C7 | 1.481 (4) | C2'—C3' | 1.454 (5) |
C1—C6 | 1.389 (5) | C3'—C4' | 1.322 (5) |
C1—C2 | 1.409 (5) | C3'—H3' | 0.9500 |
C1—C7 | 1.506 (5) | C4'—C5' | 1.516 (5) |
C2—C3 | 1.363 (5) | O5—C10' | 1.422 (5) |
C2—H2 | 0.9500 | O5—C5' | 1.447 (5) |
C3—C4 | 1.389 (5) | C5'—C6' | 1.502 (5) |
C4—C5 | 1.368 (6) | C6'—H6' | 0.9500 |
C5—C6 | 1.402 (5) | C7'—C8' | 1.497 (6) |
C5—H5 | 0.9500 | C7'—H7'1 | 0.9900 |
C6—H6 | 0.9500 | C7'—H7'2 | 0.9900 |
C7—C8 | 1.539 (5) | C8'—C9' | 1.312 (7) |
C7—H7 | 1.0000 | C8'—H8' | 0.9500 |
C8—C9 | 1.529 (5) | C9'—H9'1 | 0.9500 |
C8—C5' | 1.534 (5) | C9'—H9'2 | 0.9500 |
C8—H8 | 1.0000 | C10'—H10C | 0.9800 |
C9—H9A | 0.9800 | C10'—H10D | 0.9800 |
C9—H9B | 0.9800 | C10'—H10E | 0.9800 |
C3—O1—C10 | 104.6 (3) | O2—C10—H10B | 110.3 |
C4—O2—C10 | 104.6 (3) | H10A—C10—H10B | 108.6 |
C4'—O4—C7 | 108.7 (3) | C6'—C1'—C2' | 120.7 (3) |
C6—C1—C2 | 120.6 (3) | C6'—C1'—C7' | 124.5 (4) |
C6—C1—C7 | 119.4 (3) | C2'—C1'—C7' | 114.7 (3) |
C2—C1—C7 | 119.9 (3) | O3—C2'—C3' | 121.8 (4) |
C3—C2—C1 | 116.7 (3) | O3—C2'—C1' | 119.4 (3) |
C3—C2—H2 | 121.6 | C3'—C2'—C1' | 118.8 (3) |
C1—C2—H2 | 121.6 | C4'—C3'—C2' | 118.9 (4) |
C2—C3—O1 | 128.3 (3) | C4'—C3'—H3' | 120.5 |
C2—C3—C4 | 122.3 (4) | C2'—C3'—H3' | 120.5 |
O1—C3—C4 | 109.4 (3) | C3'—C4'—O4 | 125.7 (4) |
C5—C4—O2 | 128.3 (3) | C3'—C4'—C5' | 125.5 (3) |
C5—C4—C3 | 122.2 (3) | O4—C4'—C5' | 108.7 (3) |
O2—C4—C3 | 109.5 (3) | C10'—O5—C5' | 116.0 (3) |
C4—C5—C6 | 116.3 (3) | O5—C5'—C6' | 108.8 (3) |
C4—C5—H5 | 121.8 | O5—C5'—C4' | 110.5 (3) |
C6—C5—H5 | 121.8 | C6'—C5'—C4' | 112.6 (3) |
C1—C6—C5 | 121.8 (4) | O5—C5'—C8 | 105.2 (3) |
C1—C6—H6 | 119.1 | C6'—C5'—C8 | 119.9 (3) |
C5—C6—H6 | 119.1 | C4'—C5'—C8 | 99.2 (3) |
O4—C7—C1 | 108.9 (3) | C1'—C6'—C5' | 122.3 (3) |
O4—C7—C8 | 104.0 (3) | C1'—C6'—H6' | 118.8 |
C1—C7—C8 | 116.6 (3) | C5'—C6'—H6' | 118.8 |
O4—C7—H7 | 109.0 | C8'—C7'—C1' | 114.8 (3) |
C1—C7—H7 | 109.0 | C8'—C7'—H7'1 | 108.6 |
C8—C7—H7 | 109.0 | C1'—C7'—H7'1 | 108.6 |
C9—C8—C5' | 116.9 (3) | C8'—C7'—H7'2 | 108.6 |
C9—C8—C7 | 111.8 (3) | C1'—C7'—H7'2 | 108.6 |
C5'—C8—C7 | 99.7 (3) | H7'1—C7'—H7'2 | 107.5 |
C9—C8—H8 | 109.3 | C9'—C8'—C7' | 123.7 (5) |
C5'—C8—H8 | 109.3 | C9'—C8'—H8' | 118.1 |
C7—C8—H8 | 109.3 | C7'—C8'—H8' | 118.1 |
C8—C9—H9A | 109.5 | C8'—C9'—H9'1 | 120.0 |
C8—C9—H9B | 109.5 | C8'—C9'—H9'2 | 120.0 |
H9A—C9—H9B | 109.5 | H9'1—C9'—H9'2 | 120.0 |
C8—C9—H9C | 109.5 | O5—C10'—H10C | 109.5 |
H9A—C9—H9C | 109.5 | O5—C10'—H10D | 109.5 |
H9B—C9—H9C | 109.5 | H10C—C10'—H10D | 109.5 |
O1—C10—O2 | 107.0 (3) | O5—C10'—H10E | 109.5 |
O1—C10—H10A | 110.3 | H10C—C10'—H10E | 109.5 |
O2—C10—H10A | 110.3 | H10D—C10'—H10E | 109.5 |
O1—C10—H10B | 110.3 | ||
C6—C1—C2—C3 | −2.1 (5) | C6'—C1'—C2'—C3' | −1.6 (6) |
C7—C1—C2—C3 | 175.9 (4) | C7'—C1'—C2'—C3' | 178.0 (3) |
C1—C2—C3—O1 | −178.5 (3) | O3—C2'—C3'—C4' | −176.4 (4) |
C1—C2—C3—C4 | 1.0 (6) | C1'—C2'—C3'—C4' | 1.0 (6) |
C10—O1—C3—C2 | 165.7 (4) | C2'—C3'—C4'—O4 | 169.4 (4) |
C10—O1—C3—C4 | −13.8 (4) | C2'—C3'—C4'—C5' | −6.8 (6) |
C10—O2—C4—C5 | −167.4 (4) | C7—O4—C4'—C3' | −162.2 (4) |
C10—O2—C4—C3 | 12.7 (4) | C7—O4—C4'—C5' | 14.5 (4) |
C2—C3—C4—C5 | 1.2 (6) | C10'—O5—C5'—C6' | −66.5 (4) |
O1—C3—C4—C5 | −179.2 (4) | C10'—O5—C5'—C4' | 57.6 (4) |
C2—C3—C4—O2 | −178.9 (4) | C10'—O5—C5'—C8 | 163.8 (3) |
O1—C3—C4—O2 | 0.7 (4) | C3'—C4'—C5'—O5 | −110.0 (4) |
O2—C4—C5—C6 | 177.9 (4) | O4—C4'—C5'—O5 | 73.3 (4) |
C3—C4—C5—C6 | −2.2 (6) | C3'—C4'—C5'—C6' | 11.9 (6) |
C2—C1—C6—C5 | 1.1 (6) | O4—C4'—C5'—C6' | −164.8 (3) |
C7—C1—C6—C5 | −176.9 (4) | C3'—C4'—C5'—C8 | 139.9 (4) |
C4—C5—C6—C1 | 1.1 (6) | O4—C4'—C5'—C8 | −36.9 (4) |
C4'—O4—C7—C1 | 139.0 (3) | C9—C8—C5'—O5 | 48.5 (4) |
C4'—O4—C7—C8 | 14.1 (4) | C7—C8—C5'—O5 | −72.0 (3) |
C6—C1—C7—O4 | 133.0 (4) | C9—C8—C5'—C6' | −74.2 (5) |
C2—C1—C7—O4 | −45.0 (4) | C7—C8—C5'—C6' | 165.2 (3) |
C6—C1—C7—C8 | −109.8 (4) | C9—C8—C5'—C4' | 162.9 (3) |
C2—C1—C7—C8 | 72.2 (4) | C7—C8—C5'—C4' | 42.3 (3) |
O4—C7—C8—C9 | −159.9 (3) | C2'—C1'—C6'—C5' | 7.8 (6) |
C1—C7—C8—C9 | 80.2 (4) | C7'—C1'—C6'—C5' | −171.8 (4) |
O4—C7—C8—C5' | −35.7 (3) | O5—C5'—C6'—C1' | 110.8 (4) |
C1—C7—C8—C5' | −155.6 (3) | C4'—C5'—C6'—C1' | −12.1 (5) |
C3—O1—C10—O2 | 21.5 (4) | C8—C5'—C6'—C1' | −128.2 (4) |
C4—O2—C10—O1 | −21.1 (4) | C6'—C1'—C7'—C8' | 4.3 (6) |
C6'—C1'—C2'—O3 | 175.8 (4) | C2'—C1'—C7'—C8' | −175.3 (4) |
C7'—C1'—C2'—O3 | −4.5 (5) | C1'—C7'—C8'—C9' | −125.4 (4) |
Experimental details
Crystal data | |
Chemical formula | C20H20O5 |
Mr | 340.36 |
Crystal system, space group | Monoclinic, C2 |
Temperature (K) | 100 |
a, b, c (Å) | 17.8678 (17), 6.7905 (18), 16.382 (2) |
β (°) | 120.114 (10) |
V (Å3) | 1719.4 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.45 × 0.20 × 0.15 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3590, 2619, 1813 |
Rint | 0.056 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.061, 0.166, 1.04 |
No. of reflections | 2619 |
No. of parameters | 228 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.42, −0.23 |
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.
O3—C2' | 1.233 (5) | C3'—C4' | 1.322 (5) |
C1'—C6' | 1.333 (5) | C8'—C9' | 1.312 (7) |
C4'—O4—C7 | 108.7 (3) | C9'—C8'—C7' | 123.7 (5) |
C4'—O4—C7—C8 | 14.1 (4) | O4—C4'—C5'—C8 | −36.9 (4) |
C2—C1—C7—O4 | −45.0 (4) | C7—C8—C5'—C4' | 42.3 (3) |
O4—C7—C8—C5' | −35.7 (3) | C6'—C1'—C7'—C8' | 4.3 (6) |
C7—O4—C4'—C5' | 14.5 (4) | C1'—C7'—C8'—C9' | −125.4 (4) |
C10'—O5—C5'—C4' | 57.6 (4) |
The title neolignan, (I), has previously been reported from Magnolia denudata (Iida et al., 1982; Kuroyanagi et al., 2000), Magnolia liliflora (Iida & Ito, 1983) and Magnolia soulangiana (Abdallah, 1993).
The furan ring has the half-chair conformation with its O atom on the twist axis, as shown by the torsion angles in Table 1. The semiquinone ring is only slightly non-planar, with its six C atoms exhibiting an r.m.s. deviation of 0.039 Å from coplanarity, with a maximum deviation of 0.065 (3) Å. The propenyl group is twisted out of the semiquinone-ring plane primarily by rotation about the C7'—C8' bond, as indicated by the C1'—C7'—C8'—C9' torsion angle of -125.4 (4)°.
The most closely related neolignan for which the crystal structure has been previously reported is mirandin-A (Tomita, et al., 1977), which differs from the title compound, (I), in having the opposite configuration at C5' and by having a 3,4,5-trimethoxyphenyl substituent rather than the 3,4-methylenedioxyphenyl group of denudatin A. In mirandin-A, the furan ring also has a twist conformation, but with C7 on the twist axis. Its propenyl group also has a different conformation, with a C6'—C1'—C7'—C8' torsion angle of -92.7° and a C1'—C7'—C8'—C9' torsion angle of 2.0°.