organic compounds
5-Hydroxy-6,7-dimethoxy-2-[(E)-1-(4-methoxyphenyl)methylidene]-3,4-dihydro-2H-napthalen-1-one
aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
*Correspondence e-mail: w.harrison@abdn.ac.uk
The title compound, C20H20O5, possesses normal geometrical parameters. O—H⋯O bonds and possible C—H⋯O interactions are present.
Comment
The title compound, commonly called 2(4-methoxybenzylidene)-5-hydroxy-6,7-dimethoxytetral-1-one, (I), prepared by the condensation of anisaldehyde with 5-hydroxy-6,7-dimethoxytetral-1-one, was found to be sensitive to aerial oxidation. Its was determined in the hope of identifying structural features which might explain its ready oxidation.
All the geometrical parameters for (I) (Fig. 1 and Table 1) lie within their expected ranges (Allen et al., 1995). The six-membered C9–C14 ring adopts an envelope configuration, with C9 and C11–C14 approximately coplanar [r.m.s. deviation = 0.054 Å, maximum deviation = 0.0846 (10) for atom C14] and C10 in the flap position, displaced by 0.637 (2) Å from the mean plane. The dihedral angle between the C3 and C15 benzene rings is 66.90 (4)°. The terminal methyl groups are displaced from their attached benzene ring C-atom mean planes by 0.066 (3), 0.079 (3), and −1.113 (3) Å for atoms C1, C19, and C20, respectively.
Various O—H⋯O and possible C—H⋯O interactions exist in the (Table 2). The O3—H1 group forms a bifurcated intramolecular/intermolecular hydrogen bond. The intermolecular O—H⋯O connectivity results in chains of (I) propagating along [010]. Pairs of inversion-symmetry-related C3-benzene rings interact by π–πi [symmetry code: (i) − x, − y, 1 − z] stacking with a centroid separation of 3.6516 (9) Å and an interplane separation of 3.451 Å. Overall, we cannot observe any unusual structural features in (I) that correlate with its sensitivity to oxidation.
of (I)Experimental
A stirred solution of 102 mg of 5-hydroxy-6,7-dimethoxytetral-1-one (Cooke & Robinson, 1970) and 100 mg of 4-methoxybenzaldehyde in ethanol (10 ml) was treated dropwise with concentrated sulfuric acid (1.2 ml) over a period of 10 min (slight exothermic reaction) and the pale-brown solution was left at room temperature for 5 d. The crystals that had formed were collected and washed with cold ethanol. Recrystallization from ethanol gave (I) as pale-yellow needles (124 mg, 80%; m.p. 412–413 K) UV-vis: λmax 334 nm (∊ = 16,100); νmax (cm−1) 3312, 1654, 1600, 1578, 1252, 1167, 1120, 1009, 928, 824; 13C NMR (100 MHz): δ 21.27, 26.78, 55.33, 55.95, 61.06, 102.81, 113.92, 123.61, 128.51, 129.17, 131.66, 133.79, 136.33, 139.41, 145.70, 150.80, 159.85, and 187.28. The crystals were sensitive to oxidation, turning red on exposure to air. TLC investigations revealed a complex mixture of oxidation products. The compound was also oxidized by high-potential in methanol or dioxane solution, again giving an intractable mixture of products.
Crystal data
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Refinement
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The O-bound H atom was located in a difference map. Its position was freely refined with the constraint Uiso(H) = 1.2Ueq(O) applied. All the C-bound H atoms were placed in calculated positions (C—H = 0.95–0.99 Å) and refined as riding, with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C). The methyl groups were allowed to rotate to best fit the electron density.
Data collection: COLLECT (Nonius, 1998); cell SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997), and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
Supporting information
10.1107/S1600536805041097/wk6071sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536805041097/wk6071Isup2.hkl
A stirred solution of 102 mg of 5-hydroxy-6,7-dimethoxytetral-1-one (Cooke & Robinson, 1970) and 100 mg of 4-methoxybenzaldehyde in ethanol (10 ml) was treated dropwise with concentrated sulfuric acid (1.2 ml) over a period of 10 min (slight exothermic reaction) and the pale-brown solution was left at room temperature for 5 d. The crystals that had formed were collected and washed with cold ethanol. Recrystallization from ethanol gave (I) as pale-yellow needles (124 mg, 80%; m.p. 412–413 K) UV-vis: λmax 334 nm (ε = 16,100); νmax (cm−1) 3312, 1654, 1600, 1578, 1252, 1167, 1120, 1009, 928, 824; 13C NMR (100 MHz): δ 21.27, 26.78, 55.33, 55.95, 61.06, 102.81, 113.92, 123.61, 128.51, 129.17, 131.66, 133.79, 136.33, 139.41, 145.70, 150.80, 159.85, and 187.28. The crystals were sensitive to oxidation, turning red on exposure to air. TLC investigations revealed a complex mixture of oxidation products. The compound was also oxidized by high-potential in methanol or dioxane solution, again giving an intractable mixture of products.
The O-bound H atom was located in a difference map. Its position was freely refined with the constraint Uiso(H) = 1.2Ueq(O) applied. All the C-bound H atoms were placed in calculated positions (C—H = 0.95–0.99 Å) and refined as riding, with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C). The methyl groups was allowed to rotate to best fit the electron density.
Data collection: COLLECT (Nonius, 1998); cell
SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997), and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.C20H20O5 | F(000) = 1440 |
Mr = 340.36 | Dx = 1.347 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 3939 reflections |
a = 18.3264 (5) Å | θ = 2.9–27.5° |
b = 13.3022 (5) Å | µ = 0.10 mm−1 |
c = 15.7673 (6) Å | T = 120 K |
β = 119.1321 (16)° | Block, pale yellow |
V = 3357.5 (2) Å3 | 0.22 × 0.20 × 0.12 mm |
Z = 8 |
Nonius KappaCCD diffractometer | 3856 independent reflections |
Radiation source: fine-focus sealed tube | 3231 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
ϕ and ω scans | θmax = 27.5°, θmin = 3.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2003) | h = −23→23 |
Tmin = 0.979, Tmax = 0.989 | k = −17→17 |
20240 measured reflections | l = −20→20 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difmap (O-H) and geom (C-H) |
R[F2 > 2σ(F2)] = 0.045 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.114 | w = 1/[σ2(Fo2) + (0.0447P)2 + 3.3509P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
3856 reflections | Δρmax = 0.28 e Å−3 |
233 parameters | Δρmin = −0.23 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0030 (5) |
C20H20O5 | V = 3357.5 (2) Å3 |
Mr = 340.36 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 18.3264 (5) Å | µ = 0.10 mm−1 |
b = 13.3022 (5) Å | T = 120 K |
c = 15.7673 (6) Å | 0.22 × 0.20 × 0.12 mm |
β = 119.1321 (16)° |
Nonius KappaCCD diffractometer | 3856 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2003) | 3231 reflections with I > 2σ(I) |
Tmin = 0.979, Tmax = 0.989 | Rint = 0.042 |
20240 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.114 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.28 e Å−3 |
3856 reflections | Δρmin = −0.23 e Å−3 |
233 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 | ||
C1 | 0.89149 (10) | 0.29139 (12) | 0.40275 (12) | 0.0293 (4) | |
H1A | 0.9509 | 0.3029 | 0.4249 | 0.044* | |
H1B | 0.8599 | 0.2957 | 0.3318 | 0.044* | |
H1C | 0.8841 | 0.2245 | 0.4234 | 0.044* | |
C2 | 0.78079 (9) | 0.35687 (11) | 0.42500 (10) | 0.0215 (3) | |
C3 | 0.75285 (9) | 0.42983 (11) | 0.46647 (11) | 0.0232 (3) | |
H3 | 0.7889 | 0.4831 | 0.5033 | 0.028* | |
C4 | 0.67302 (9) | 0.42464 (11) | 0.45401 (10) | 0.0215 (3) | |
H4 | 0.6545 | 0.4747 | 0.4822 | 0.026* | |
C5 | 0.61872 (9) | 0.34639 (10) | 0.40022 (10) | 0.0200 (3) | |
C6 | 0.64855 (9) | 0.27408 (11) | 0.36052 (11) | 0.0228 (3) | |
H6 | 0.6133 | 0.2197 | 0.3251 | 0.027* | |
C7 | 0.72791 (9) | 0.27932 (11) | 0.37116 (11) | 0.0236 (3) | |
H7 | 0.7461 | 0.2302 | 0.3418 | 0.028* | |
C8 | 0.53592 (9) | 0.33069 (11) | 0.38987 (10) | 0.0206 (3) | |
H8 | 0.5207 | 0.2621 | 0.3878 | 0.025* | |
C9 | 0.47747 (9) | 0.39649 (10) | 0.38278 (10) | 0.0198 (3) | |
C10 | 0.47752 (9) | 0.50872 (10) | 0.36893 (10) | 0.0201 (3) | |
H10A | 0.5238 | 0.5272 | 0.3565 | 0.024* | |
H10B | 0.4865 | 0.5435 | 0.4288 | 0.024* | |
C11 | 0.39419 (9) | 0.54235 (11) | 0.28324 (10) | 0.0208 (3) | |
H11A | 0.3924 | 0.6167 | 0.2799 | 0.025* | |
H11B | 0.3899 | 0.5167 | 0.2220 | 0.025* | |
C12 | 0.32103 (8) | 0.50453 (10) | 0.29296 (10) | 0.0191 (3) | |
C13 | 0.32654 (9) | 0.41647 (10) | 0.34387 (10) | 0.0197 (3) | |
C14 | 0.40214 (9) | 0.35263 (10) | 0.38071 (10) | 0.0205 (3) | |
C15 | 0.25951 (9) | 0.38177 (11) | 0.35495 (11) | 0.0220 (3) | |
H15 | 0.2650 | 0.3219 | 0.3904 | 0.026* | |
C16 | 0.18553 (9) | 0.43493 (11) | 0.31411 (11) | 0.0231 (3) | |
C17 | 0.17730 (9) | 0.52133 (11) | 0.25892 (11) | 0.0225 (3) | |
C18 | 0.24411 (9) | 0.55464 (11) | 0.24764 (10) | 0.0206 (3) | |
C19 | 0.12370 (12) | 0.32182 (13) | 0.37813 (16) | 0.0405 (4) | |
H19A | 0.0704 | 0.3096 | 0.3769 | 0.061* | |
H19B | 0.1677 | 0.3323 | 0.4453 | 0.061* | |
H19C | 0.1378 | 0.2636 | 0.3508 | 0.061* | |
C20 | 0.03432 (10) | 0.53371 (13) | 0.13886 (14) | 0.0375 (4) | |
H20A | −0.0113 | 0.5828 | 0.1106 | 0.056* | |
H20B | 0.0167 | 0.4755 | 0.1625 | 0.056* | |
H20C | 0.0485 | 0.5119 | 0.0893 | 0.056* | |
O1 | 0.86164 (6) | 0.36594 (8) | 0.44389 (8) | 0.0279 (3) | |
O2 | 0.40156 (6) | 0.26562 (8) | 0.40761 (8) | 0.0273 (3) | |
O3 | 0.23724 (7) | 0.63713 (8) | 0.19300 (8) | 0.0249 (3) | |
H1 | 0.1879 (12) | 0.6628 (14) | 0.1686 (13) | 0.030* | |
O4 | 0.11660 (7) | 0.40919 (8) | 0.32184 (9) | 0.0307 (3) | |
O5 | 0.10613 (6) | 0.57905 (8) | 0.21820 (8) | 0.0282 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0298 (8) | 0.0329 (9) | 0.0298 (8) | 0.0080 (7) | 0.0181 (7) | 0.0051 (7) |
C2 | 0.0208 (7) | 0.0228 (7) | 0.0202 (7) | 0.0030 (5) | 0.0095 (6) | 0.0049 (6) |
C3 | 0.0245 (7) | 0.0198 (7) | 0.0218 (7) | −0.0007 (6) | 0.0085 (6) | −0.0006 (6) |
C4 | 0.0241 (7) | 0.0183 (7) | 0.0201 (7) | 0.0025 (5) | 0.0091 (6) | −0.0008 (5) |
C5 | 0.0219 (7) | 0.0176 (7) | 0.0173 (7) | 0.0025 (5) | 0.0071 (6) | 0.0027 (5) |
C6 | 0.0249 (7) | 0.0175 (7) | 0.0230 (7) | 0.0005 (6) | 0.0093 (6) | −0.0009 (6) |
C7 | 0.0275 (7) | 0.0209 (7) | 0.0227 (7) | 0.0038 (6) | 0.0126 (6) | −0.0006 (6) |
C8 | 0.0230 (7) | 0.0157 (7) | 0.0194 (7) | −0.0007 (5) | 0.0073 (6) | 0.0004 (5) |
C9 | 0.0204 (7) | 0.0183 (7) | 0.0176 (7) | −0.0009 (5) | 0.0067 (6) | −0.0005 (5) |
C10 | 0.0207 (7) | 0.0170 (7) | 0.0218 (7) | −0.0005 (5) | 0.0098 (6) | 0.0003 (5) |
C11 | 0.0229 (7) | 0.0177 (7) | 0.0227 (7) | 0.0025 (5) | 0.0119 (6) | 0.0017 (5) |
C12 | 0.0206 (7) | 0.0172 (7) | 0.0180 (7) | 0.0003 (5) | 0.0083 (6) | −0.0039 (5) |
C13 | 0.0203 (7) | 0.0176 (7) | 0.0187 (7) | −0.0012 (5) | 0.0074 (6) | −0.0041 (5) |
C14 | 0.0219 (7) | 0.0174 (7) | 0.0179 (7) | −0.0005 (5) | 0.0063 (6) | −0.0013 (5) |
C15 | 0.0244 (7) | 0.0173 (7) | 0.0237 (7) | −0.0026 (5) | 0.0112 (6) | −0.0037 (6) |
C16 | 0.0225 (7) | 0.0199 (7) | 0.0283 (8) | −0.0044 (6) | 0.0135 (6) | −0.0083 (6) |
C17 | 0.0199 (7) | 0.0186 (7) | 0.0269 (8) | 0.0009 (5) | 0.0097 (6) | −0.0067 (6) |
C18 | 0.0241 (7) | 0.0153 (7) | 0.0203 (7) | 0.0007 (5) | 0.0091 (6) | −0.0031 (5) |
C19 | 0.0414 (10) | 0.0286 (9) | 0.0667 (13) | −0.0028 (7) | 0.0382 (10) | 0.0037 (8) |
C20 | 0.0239 (8) | 0.0273 (9) | 0.0457 (11) | 0.0008 (6) | 0.0047 (8) | −0.0037 (7) |
O1 | 0.0229 (5) | 0.0297 (6) | 0.0331 (6) | 0.0009 (4) | 0.0151 (5) | −0.0015 (5) |
O2 | 0.0232 (5) | 0.0178 (5) | 0.0358 (6) | −0.0010 (4) | 0.0105 (5) | 0.0046 (4) |
O3 | 0.0227 (5) | 0.0195 (5) | 0.0307 (6) | 0.0063 (4) | 0.0115 (5) | 0.0049 (4) |
O4 | 0.0259 (6) | 0.0259 (6) | 0.0465 (7) | −0.0022 (4) | 0.0223 (5) | −0.0010 (5) |
O5 | 0.0196 (5) | 0.0199 (5) | 0.0402 (7) | 0.0022 (4) | 0.0106 (5) | −0.0068 (5) |
C1—O1 | 1.4314 (19) | C11—H11A | 0.9900 |
C1—H1A | 0.9800 | C11—H11B | 0.9900 |
C1—H1B | 0.9800 | C12—C13 | 1.396 (2) |
C1—H1C | 0.9800 | C12—C18 | 1.4006 (19) |
C2—O1 | 1.3670 (17) | C13—C15 | 1.401 (2) |
C2—C7 | 1.387 (2) | C13—C14 | 1.4814 (19) |
C2—C3 | 1.399 (2) | C14—O2 | 1.2345 (17) |
C3—C4 | 1.380 (2) | C15—C16 | 1.379 (2) |
C3—H3 | 0.9500 | C15—H15 | 0.9500 |
C4—C5 | 1.404 (2) | C16—O4 | 1.3703 (17) |
C4—H4 | 0.9500 | C16—C17 | 1.405 (2) |
C5—C6 | 1.396 (2) | C17—O5 | 1.3739 (17) |
C5—C8 | 1.460 (2) | C17—C18 | 1.393 (2) |
C6—C7 | 1.382 (2) | C18—O3 | 1.3625 (18) |
C6—H6 | 0.9500 | C19—O4 | 1.429 (2) |
C7—H7 | 0.9500 | C19—H19A | 0.9800 |
C8—C9 | 1.345 (2) | C19—H19B | 0.9800 |
C8—H8 | 0.9500 | C19—H19C | 0.9800 |
C9—C14 | 1.484 (2) | C20—O5 | 1.4344 (19) |
C9—C10 | 1.5089 (19) | C20—H20A | 0.9800 |
C10—C11 | 1.5326 (19) | C20—H20B | 0.9800 |
C10—H10A | 0.9900 | C20—H20C | 0.9800 |
C10—H10B | 0.9900 | O3—H1 | 0.863 (19) |
C11—C12 | 1.5079 (19) | ||
O1—C1—H1A | 109.5 | C10—C11—H11B | 109.3 |
O1—C1—H1B | 109.5 | H11A—C11—H11B | 108.0 |
H1A—C1—H1B | 109.5 | C13—C12—C18 | 117.77 (13) |
O1—C1—H1C | 109.5 | C13—C12—C11 | 121.30 (12) |
H1A—C1—H1C | 109.5 | C18—C12—C11 | 120.88 (13) |
H1B—C1—H1C | 109.5 | C12—C13—C15 | 121.75 (13) |
O1—C2—C7 | 124.01 (13) | C12—C13—C14 | 119.91 (12) |
O1—C2—C3 | 116.18 (13) | C15—C13—C14 | 118.15 (13) |
C7—C2—C3 | 119.77 (13) | O2—C14—C13 | 120.63 (13) |
C4—C3—C2 | 120.17 (14) | O2—C14—C9 | 121.63 (13) |
C4—C3—H3 | 119.9 | C13—C14—C9 | 117.74 (12) |
C2—C3—H3 | 119.9 | C16—C15—C13 | 119.69 (14) |
C3—C4—C5 | 120.91 (13) | C16—C15—H15 | 120.2 |
C3—C4—H4 | 119.5 | C13—C15—H15 | 120.2 |
C5—C4—H4 | 119.5 | O4—C16—C15 | 124.72 (14) |
C6—C5—C4 | 117.68 (13) | O4—C16—C17 | 115.72 (13) |
C6—C5—C8 | 117.64 (13) | C15—C16—C17 | 119.55 (13) |
C4—C5—C8 | 124.46 (13) | O5—C17—C18 | 117.14 (13) |
C7—C6—C5 | 121.96 (14) | O5—C17—C16 | 122.55 (13) |
C7—C6—H6 | 119.0 | C18—C17—C16 | 120.24 (13) |
C5—C6—H6 | 119.0 | O3—C18—C17 | 121.38 (13) |
C6—C7—C2 | 119.49 (13) | O3—C18—C12 | 117.78 (13) |
C6—C7—H7 | 120.3 | C17—C18—C12 | 120.84 (13) |
C2—C7—H7 | 120.3 | O4—C19—H19A | 109.5 |
C9—C8—C5 | 131.19 (13) | O4—C19—H19B | 109.5 |
C9—C8—H8 | 114.4 | H19A—C19—H19B | 109.5 |
C5—C8—H8 | 114.4 | O4—C19—H19C | 109.5 |
C8—C9—C14 | 116.14 (13) | H19A—C19—H19C | 109.5 |
C8—C9—C10 | 126.81 (13) | H19B—C19—H19C | 109.5 |
C14—C9—C10 | 116.86 (12) | O5—C20—H20A | 109.5 |
C9—C10—C11 | 110.23 (12) | O5—C20—H20B | 109.5 |
C9—C10—H10A | 109.6 | H20A—C20—H20B | 109.5 |
C11—C10—H10A | 109.6 | O5—C20—H20C | 109.5 |
C9—C10—H10B | 109.6 | H20A—C20—H20C | 109.5 |
C11—C10—H10B | 109.6 | H20B—C20—H20C | 109.5 |
H10A—C10—H10B | 108.1 | C2—O1—C1 | 116.93 (12) |
C12—C11—C10 | 111.52 (11) | C18—O3—H1 | 110.8 (12) |
C12—C11—H11A | 109.3 | C16—O4—C19 | 116.69 (12) |
C10—C11—H11A | 109.3 | C17—O5—C20 | 115.58 (11) |
C12—C11—H11B | 109.3 | ||
O1—C2—C3—C4 | −177.79 (13) | C8—C9—C14—O2 | 17.3 (2) |
C7—C2—C3—C4 | 0.1 (2) | C10—C9—C14—O2 | −167.35 (13) |
C2—C3—C4—C5 | 0.3 (2) | C8—C9—C14—C13 | −161.95 (13) |
C3—C4—C5—C6 | 0.4 (2) | C10—C9—C14—C13 | 13.43 (18) |
C3—C4—C5—C8 | 174.93 (13) | C12—C13—C15—C16 | 0.6 (2) |
C4—C5—C6—C7 | −1.4 (2) | C14—C13—C15—C16 | −174.39 (13) |
C8—C5—C6—C7 | −176.37 (13) | C13—C15—C16—O4 | −178.69 (13) |
C5—C6—C7—C2 | 1.8 (2) | C13—C15—C16—C17 | 2.3 (2) |
O1—C2—C7—C6 | 176.59 (13) | O4—C16—C17—O5 | 2.5 (2) |
C3—C2—C7—C6 | −1.1 (2) | C15—C16—C17—O5 | −178.41 (13) |
C6—C5—C8—C9 | −149.65 (16) | O4—C16—C17—C18 | 179.17 (13) |
C4—C5—C8—C9 | 35.8 (2) | C15—C16—C17—C18 | −1.7 (2) |
C5—C8—C9—C14 | −175.38 (14) | O5—C17—C18—O3 | −4.4 (2) |
C5—C8—C9—C10 | 9.8 (3) | C16—C17—C18—O3 | 178.77 (13) |
C8—C9—C10—C11 | 128.49 (15) | O5—C17—C18—C12 | 175.17 (13) |
C14—C9—C10—C11 | −46.34 (16) | C16—C17—C18—C12 | −1.7 (2) |
C9—C10—C11—C12 | 52.21 (16) | C13—C12—C18—O3 | −176.06 (12) |
C10—C11—C12—C13 | −27.58 (18) | C11—C12—C18—O3 | 1.4 (2) |
C10—C11—C12—C18 | 155.07 (13) | C13—C12—C18—C17 | 4.4 (2) |
C18—C12—C13—C15 | −3.9 (2) | C11—C12—C18—C17 | −178.16 (13) |
C11—C12—C13—C15 | 178.71 (13) | C7—C2—O1—C1 | 1.7 (2) |
C18—C12—C13—C14 | 170.99 (12) | C3—C2—O1—C1 | 179.45 (13) |
C11—C12—C13—C14 | −6.4 (2) | C15—C16—O4—C19 | 1.3 (2) |
C12—C13—C14—O2 | −164.91 (14) | C17—C16—O4—C19 | −179.67 (14) |
C15—C13—C14—O2 | 10.1 (2) | C18—C17—O5—C20 | 113.18 (16) |
C12—C13—C14—C9 | 14.32 (19) | C16—C17—O5—C20 | −70.03 (19) |
C15—C13—C14—C9 | −170.65 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H1···O2i | 0.863 (19) | 2.02 (2) | 2.8248 (15) | 154.8 (17) |
O3—H1···O5 | 0.863 (19) | 2.289 (18) | 2.7308 (15) | 111.9 (15) |
C6—H6···O5ii | 0.95 | 2.48 | 3.2668 (18) | 140 |
C7—H7···O3ii | 0.95 | 2.59 | 3.4591 (18) | 153 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) x+1/2, y−1/2, z. |
Experimental details
Crystal data | |
Chemical formula | C20H20O5 |
Mr | 340.36 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 120 |
a, b, c (Å) | 18.3264 (5), 13.3022 (5), 15.7673 (6) |
β (°) | 119.1321 (16) |
V (Å3) | 3357.5 (2) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.22 × 0.20 × 0.12 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2003) |
Tmin, Tmax | 0.979, 0.989 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 20240, 3856, 3231 |
Rint | 0.042 |
(sin θ/λ)max (Å−1) | 0.651 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.114, 1.07 |
No. of reflections | 3856 |
No. of parameters | 233 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.28, −0.23 |
Computer programs: COLLECT (Nonius, 1998), SCALEPACK (Otwinowski & Minor, 1997), SCALEPACK and DENZO (Otwinowski & Minor, 1997), and SORTAV (Blessing, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), SHELXL97.
C5—C8 | 1.460 (2) | C13—C14 | 1.4814 (19) |
C9—C14 | 1.484 (2) | ||
C9—C10—C11—C12 | 52.21 (16) | C12—C13—C14—C9 | 14.32 (19) |
C10—C11—C12—C13 | −27.58 (18) | C10—C9—C14—C13 | 13.43 (18) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H1···O2i | 0.863 (19) | 2.02 (2) | 2.8248 (15) | 154.8 (17) |
O3—H1···O5 | 0.863 (19) | 2.289 (18) | 2.7308 (15) | 111.9 (15) |
C6—H6···O5ii | 0.95 | 2.48 | 3.2668 (18) | 140 |
C7—H7···O3ii | 0.95 | 2.59 | 3.4591 (18) | 153 |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) x+1/2, y−1/2, z. |
Acknowledgements
We thank the EPSRC National Crystallography Service (University of Southampton) for data collection.
References
Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1995). International Tables for Crystallography, Vol. C, Section 9.5, pp. 685–706. Dordrecht: Kluwer Academic Publishers. Google Scholar
Blessing, R. H. (1995). Acta Cryst. A51, 33–38. CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2003). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cooke, R. G. & Robinson, J. B. (1970). Aust. J. Chem. 23, 1695–1698. CrossRef CAS Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
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Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
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The title compound, commonly called 2(4-methoxybenzylidene)-5-hydroxy-6,7-dimethoxytetral-1-one, (I), prepared by the condensation of anisaldehyde with 5-hydroxy-6,7-dimethoxytetral-1-one, was found to be sensitive to aerial oxidation. Its crystal structure was determined in the hope of identifying structural features which might explain its ready oxidation.
All the geometrical parameters for (I) (Fig. 1 and Table 1) lie within their expected ranges (Allen et al., 1995). The six-membered C9–C14 ring adopts an envelope configuration, with C9 and C11–C14 approximately co-planar [r.m.s. deviation = 0.054 Å, maximum deviation = −0.0846 (10) for atom C14] and C10 in the flap position, displaced by 0.637 (2) Å from the best plane. The dihedral angle between the C3 and C15 benzene rings is 66.90 (4)°. The terminal methyl groups are displaced from their attached benzene ring C-atom best planes by 0.066 (3), 0.079 (3), and −1.113 (3) Å for atoms C1, C19, and C20, respectively.
Various O—H···O and possible C—H···O interactions exist in the crystal structure of (I) (Table 2). The O3—H1 moiety forms a bifurcated intramolecular/intermolecular hydrogen bond. The intermolecular O—H···O connectivity results in chains of (I) propagating in [010]. Pairs of inversion-symmetry-generated C3-benzene rings interact by π–πi [symmetry code: (i) 3/2 − x, 1/2 − y, 1 − z] stacking with a centroid separation of 3.6516 (9) Å and an interplane separation of 3.451 Å. Overall, we cannot observe any unusual structural features in (I) that correlate with its sensitivity to oxidation.