Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101011842/de1171sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270101011842/de1171Isup2.hkl |
CCDC reference: 174838
The synthesis of (I) was carried out by hydrolysing β,β-dimethyl acryloyl shikonin with sodium hydroxide, followed by esterification with cinnamic anhydride or cinnamoyl chloride or cinnamic acid and DCC. Which procedure was used here? Define DCC. Crystals of (I) of diffraction quality were grown from hexane-methylene chloride solution (is a mixed solvent correct?) at room temperature.
The hydroxyl H atoms H5 and H8 were located from the difference Fourier map and refined freely. The remaining H atoms were placed in geometrically idealized positions and allowed to ride on their parent atoms, with C—H = 093–0.98 Å and Uiso(H) = 1.2Ueq(C). Query. Three reflections [most disagreeable, Δ(F2)/σ > 6.4] were suppressed during the last cycles of refinement.
Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: NRCVAX (Gabe et al., 1989), ORTEP (Johnson, 1965) and PLUTO (Motherwell & Clegg, 1978); software used to prepare material for publication: SHELXL97.
C25H22O6 | Dx = 1.361 Mg m−3 |
Mr = 418.43 | Melting point = 93–94 K |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.1677 (1) Å | Cell parameters from 510 reflections |
b = 15.7416 (3) Å | θ = 4.1–27.4° |
c = 10.5141 (2) Å | µ = 0.10 mm−1 |
β = 90.763 (1)° | T = 100 K |
V = 1020.72 (3) Å3 | Block, red |
Z = 2 | 0.5 × 0.1 × 0.1 mm |
F(000) = 440 |
Bruker SMART CCD area-detector diffractometer | 4357 independent reflections |
Radiation source: fine-focus sealed tube | 4011 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.028 |
ω scan | θmax = 27.5°, θmin = 1.9° |
Absorption correction: ψ-scan (XPREP; Sheldrick, 1994) | h = −8→7 |
Tmin = 0.885, Tmax = 1.000 | k = −20→20 |
7463 measured reflections | l = −13→11 |
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.096 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.09 | w = 1/[σ2(Fo2) + (0.0219P)2 + 0.7688P] where P = (Fo2 + 2Fc2)/3 |
4357 reflections | (Δ/σ)max = 0.002 |
290 parameters | Δρmax = 0.25 e Å−3 |
1 restraint | Δρmin = −0.25 e Å−3 |
C25H22O6 | V = 1020.72 (3) Å3 |
Mr = 418.43 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 6.1677 (1) Å | µ = 0.10 mm−1 |
b = 15.7416 (3) Å | T = 100 K |
c = 10.5141 (2) Å | 0.5 × 0.1 × 0.1 mm |
β = 90.763 (1)° |
Bruker SMART CCD area-detector diffractometer | 4357 independent reflections |
Absorption correction: ψ-scan (XPREP; Sheldrick, 1994) | 4011 reflections with I > 2σ(I) |
Tmin = 0.885, Tmax = 1.000 | Rint = 0.028 |
7463 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 1 restraint |
wR(F2) = 0.096 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.09 | Δρmax = 0.25 e Å−3 |
4357 reflections | Δρmin = −0.25 e Å−3 |
290 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 | 0.6313 (4) | 0.08045 (14) | 0.4190 (2) | 0.0173 (4) | |
O1 | 0.4586 (3) | 0.04035 (11) | 0.40111 (15) | 0.0225 (4) | |
C2 | 0.7810 (4) | 0.09387 (14) | 0.3125 (2) | 0.0198 (5) | |
H2 | 0.7436 | 0.0729 | 0.2324 | 0.024* | |
C3 | 0.9693 (4) | 0.13538 (14) | 0.3278 (2) | 0.0200 (5) | |
H3 | 1.0606 | 0.1411 | 0.2586 | 0.024* | |
C4 | 1.0356 (3) | 0.17213 (14) | 0.4512 (2) | 0.0165 (4) | |
O4 | 1.2094 (3) | 0.21283 (10) | 0.46141 (15) | 0.0207 (3) | |
C5 | 0.9503 (3) | 0.19095 (13) | 0.67999 (19) | 0.0146 (4) | |
O5 | 1.1341 (3) | 0.23606 (10) | 0.70031 (15) | 0.0184 (3) | |
H5 | 1.201 (5) | 0.240 (2) | 0.629 (3) | 0.038 (9)* | |
C6 | 0.8138 (3) | 0.17673 (14) | 0.78492 (19) | 0.0147 (4) | |
H6 | 0.8546 | 0.1974 | 0.8645 | 0.018* | |
C7 | 0.6217 (3) | 0.13288 (13) | 0.7716 (2) | 0.0148 (4) | |
C8 | 0.5603 (3) | 0.10094 (13) | 0.6490 (2) | 0.0141 (4) | |
O8 | 0.3717 (3) | 0.05787 (10) | 0.63994 (16) | 0.0190 (3) | |
H8 | 0.366 (5) | 0.038 (2) | 0.562 (3) | 0.050 (10)* | |
C9 | 0.6946 (3) | 0.11375 (13) | 0.5441 (2) | 0.0148 (4) | |
C10 | 0.8928 (4) | 0.15915 (13) | 0.5599 (2) | 0.0139 (4) | |
C11 | 0.4692 (3) | 0.11656 (13) | 0.88009 (19) | 0.0145 (4) | |
H11 | 0.3215 | 0.1316 | 0.8532 | 0.017* | |
O11 | 0.5373 (2) | 0.17241 (10) | 0.98345 (14) | 0.0166 (3) | |
C12 | 0.4713 (4) | 0.02440 (14) | 0.9277 (2) | 0.0183 (4) | |
H12A | 0.3679 | 0.0191 | 0.9960 | 0.022* | |
H12B | 0.4230 | −0.0124 | 0.8590 | 0.022* | |
C13 | 0.6898 (4) | −0.00625 (15) | 0.9753 (2) | 0.0183 (4) | |
H13 | 0.8110 | 0.0170 | 0.9367 | 0.022* | |
C14 | 0.7272 (4) | −0.06321 (14) | 1.0671 (2) | 0.0176 (4) | |
C15 | 0.9552 (4) | −0.08868 (17) | 1.1043 (2) | 0.0264 (5) | |
H15A | 0.9738 | −0.1485 | 1.0902 | 0.040* | |
H15B | 0.9802 | −0.0761 | 1.1926 | 0.040* | |
H15C | 1.0566 | −0.0576 | 1.0537 | 0.040* | |
C16 | 0.5514 (4) | −0.10676 (16) | 1.1415 (2) | 0.0243 (5) | |
H16A | 0.5406 | −0.0808 | 1.2238 | 0.036* | |
H16B | 0.5865 | −0.1658 | 1.1514 | 0.036* | |
H16C | 0.4155 | −0.1013 | 1.0967 | 0.036* | |
C17 | 0.3800 (3) | 0.20142 (15) | 1.06159 (19) | 0.0182 (4) | |
O17 | 0.1894 (3) | 0.18486 (13) | 1.04712 (15) | 0.0268 (4) | |
C18 | 0.4685 (4) | 0.25339 (15) | 1.1664 (2) | 0.0191 (4) | |
H18 | 0.3771 | 0.2668 | 1.2331 | 0.023* | |
C19 | 0.6715 (4) | 0.28248 (14) | 1.1718 (2) | 0.0176 (4) | |
H19 | 0.7571 | 0.2718 | 1.1014 | 0.021* | |
C20 | 0.7746 (4) | 0.32971 (14) | 1.2774 (2) | 0.0172 (4) | |
C21 | 0.6812 (4) | 0.33297 (14) | 1.3995 (2) | 0.0191 (4) | |
H21 | 0.5473 | 0.3078 | 1.4137 | 0.023* | |
C22 | 0.7910 (4) | 0.37412 (15) | 1.4982 (2) | 0.0224 (5) | |
H22 | 0.7304 | 0.3759 | 1.5786 | 0.027* | |
C23 | 0.9904 (4) | 0.41266 (15) | 1.4776 (2) | 0.0252 (5) | |
H23 | 1.0625 | 0.4398 | 1.5444 | 0.030* | |
C24 | 1.0823 (4) | 0.41081 (15) | 1.3576 (2) | 0.0248 (5) | |
H24 | 1.2146 | 0.4373 | 1.3437 | 0.030* | |
C25 | 0.9745 (4) | 0.36890 (15) | 1.2580 (2) | 0.0208 (5) | |
H25 | 1.0367 | 0.3671 | 1.1780 | 0.025* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0221 (11) | 0.0135 (10) | 0.0164 (10) | 0.0031 (9) | −0.0016 (8) | 0.0008 (8) |
O1 | 0.0240 (9) | 0.0254 (9) | 0.0180 (8) | −0.0034 (7) | −0.0015 (7) | −0.0046 (7) |
C2 | 0.0292 (12) | 0.0180 (11) | 0.0120 (10) | 0.0035 (9) | 0.0006 (9) | 0.0001 (8) |
C3 | 0.0257 (12) | 0.0206 (11) | 0.0139 (10) | 0.0044 (9) | 0.0057 (9) | 0.0014 (9) |
C4 | 0.0194 (11) | 0.0142 (10) | 0.0160 (10) | 0.0031 (9) | 0.0019 (8) | 0.0031 (8) |
O4 | 0.0202 (8) | 0.0217 (8) | 0.0202 (8) | −0.0016 (7) | 0.0039 (6) | 0.0024 (6) |
C5 | 0.0150 (10) | 0.0114 (10) | 0.0174 (10) | 0.0004 (8) | −0.0006 (8) | 0.0009 (8) |
O5 | 0.0167 (8) | 0.0219 (8) | 0.0166 (7) | −0.0052 (6) | 0.0027 (6) | −0.0011 (6) |
C6 | 0.0171 (10) | 0.0146 (10) | 0.0122 (9) | 0.0008 (8) | 0.0002 (8) | −0.0021 (8) |
C7 | 0.0146 (10) | 0.0144 (10) | 0.0153 (10) | 0.0019 (8) | −0.0002 (8) | 0.0024 (8) |
C8 | 0.0143 (10) | 0.0132 (10) | 0.0149 (10) | 0.0016 (8) | −0.0012 (8) | −0.0009 (8) |
O8 | 0.0172 (8) | 0.0222 (8) | 0.0176 (8) | −0.0035 (6) | −0.0011 (6) | −0.0033 (6) |
C9 | 0.0161 (10) | 0.0123 (9) | 0.0161 (10) | 0.0022 (8) | −0.0006 (8) | −0.0012 (8) |
C10 | 0.0173 (10) | 0.0137 (9) | 0.0108 (9) | 0.0011 (8) | 0.0023 (8) | 0.0013 (7) |
C11 | 0.0137 (10) | 0.0184 (10) | 0.0115 (9) | −0.0004 (8) | −0.0012 (8) | −0.0002 (8) |
O11 | 0.0146 (7) | 0.0217 (8) | 0.0134 (7) | −0.0007 (6) | 0.0023 (6) | −0.0033 (6) |
C12 | 0.0180 (11) | 0.0190 (11) | 0.0179 (10) | −0.0033 (9) | 0.0008 (8) | 0.0032 (9) |
C13 | 0.0164 (11) | 0.0226 (11) | 0.0161 (10) | −0.0004 (9) | 0.0042 (8) | 0.0012 (9) |
C14 | 0.0174 (11) | 0.0180 (11) | 0.0174 (10) | 0.0013 (9) | 0.0025 (8) | −0.0036 (8) |
C15 | 0.0182 (11) | 0.0300 (13) | 0.0310 (12) | 0.0011 (10) | −0.0001 (9) | 0.0119 (11) |
C16 | 0.0213 (11) | 0.0255 (12) | 0.0262 (12) | 0.0007 (10) | 0.0030 (9) | 0.0089 (10) |
C17 | 0.0181 (11) | 0.0239 (12) | 0.0129 (9) | 0.0019 (9) | 0.0032 (8) | 0.0035 (8) |
O17 | 0.0160 (8) | 0.0456 (11) | 0.0189 (8) | −0.0014 (8) | 0.0016 (6) | −0.0067 (8) |
C18 | 0.0204 (11) | 0.0231 (11) | 0.0140 (10) | 0.0038 (9) | 0.0019 (8) | −0.0010 (8) |
C19 | 0.0225 (11) | 0.0185 (10) | 0.0119 (9) | 0.0017 (8) | 0.0036 (8) | 0.0000 (8) |
C20 | 0.0209 (11) | 0.0138 (10) | 0.0168 (10) | 0.0028 (9) | 0.0008 (8) | −0.0010 (9) |
C21 | 0.0207 (11) | 0.0170 (10) | 0.0194 (11) | 0.0020 (9) | 0.0001 (8) | 0.0007 (9) |
C22 | 0.0339 (13) | 0.0180 (11) | 0.0154 (10) | 0.0038 (10) | 0.0021 (9) | −0.0022 (9) |
C23 | 0.0326 (13) | 0.0186 (11) | 0.0244 (11) | 0.0005 (10) | −0.0055 (10) | −0.0048 (10) |
C24 | 0.0242 (12) | 0.0176 (11) | 0.0326 (12) | −0.0033 (9) | −0.0014 (10) | −0.0010 (10) |
C25 | 0.0233 (11) | 0.0199 (11) | 0.0192 (10) | 0.0004 (9) | 0.0024 (9) | −0.0002 (9) |
C1—O1 | 1.250 (3) | C13—C14 | 1.335 (3) |
C1—C9 | 1.464 (3) | C13—H13 | 0.9300 |
C1—C2 | 1.476 (3) | C14—C16 | 1.510 (3) |
C2—C3 | 1.340 (3) | C14—C15 | 1.509 (3) |
C2—H2 | 0.9300 | C15—H15A | 0.9600 |
C3—C4 | 1.474 (3) | C15—H15B | 0.9600 |
C3—H3 | 0.9300 | C15—H15C | 0.9600 |
C4—O4 | 1.252 (3) | C16—H16A | 0.9600 |
C4—C10 | 1.467 (3) | C16—H16B | 0.9600 |
C5—O5 | 1.352 (3) | C16—H16C | 0.9600 |
C5—C10 | 1.400 (3) | C17—O17 | 1.212 (3) |
C5—C6 | 1.414 (3) | C17—C18 | 1.472 (3) |
O5—H5 | 0.87 (3) | C18—C19 | 1.334 (3) |
C6—C7 | 1.377 (3) | C18—H18 | 0.9300 |
C6—H6 | 0.9300 | C19—C20 | 1.474 (3) |
C7—C8 | 1.430 (3) | C19—H19 | 0.9300 |
C7—C11 | 1.510 (3) | C20—C25 | 1.396 (3) |
C8—O8 | 1.349 (3) | C20—C21 | 1.415 (3) |
C8—C9 | 1.403 (3) | C21—C22 | 1.391 (3) |
O8—H8 | 0.88 (4) | C21—H21 | 0.9300 |
C9—C10 | 1.424 (3) | C22—C23 | 1.391 (4) |
C11—O11 | 1.455 (2) | C22—H22 | 0.9300 |
C11—C12 | 1.535 (3) | C23—C24 | 1.390 (4) |
C11—H11 | 0.9800 | C23—H23 | 0.9300 |
O11—C17 | 1.358 (3) | C24—C25 | 1.398 (3) |
C12—C13 | 1.511 (3) | C24—H24 | 0.9300 |
C12—H12A | 0.9700 | C25—H25 | 0.9300 |
C12—H12B | 0.9700 | ||
O1—C1—C9 | 122.1 (2) | C14—C13—C12 | 126.8 (2) |
O1—C1—C2 | 119.9 (2) | C14—C13—H13 | 116.6 |
C9—C1—C2 | 118.0 (2) | C12—C13—H13 | 116.6 |
C3—C2—C1 | 121.9 (2) | C13—C14—C16 | 124.2 (2) |
C3—C2—H2 | 119.1 | C13—C14—C15 | 121.1 (2) |
C1—C2—H2 | 119.1 | C16—C14—C15 | 114.71 (19) |
C2—C3—C4 | 121.8 (2) | C14—C15—H15A | 109.5 |
C2—C3—H3 | 119.1 | C14—C15—H15B | 109.5 |
C4—C3—H3 | 119.1 | H15A—C15—H15B | 109.5 |
O4—C4—C10 | 121.78 (19) | C14—C15—H15C | 109.5 |
O4—C4—C3 | 120.26 (19) | H15A—C15—H15C | 109.5 |
C10—C4—C3 | 117.96 (19) | H15B—C15—H15C | 109.5 |
O5—C5—C10 | 122.15 (18) | C14—C16—H16A | 109.5 |
O5—C5—C6 | 117.80 (18) | C14—C16—H16B | 109.5 |
C10—C5—C6 | 120.05 (18) | H16A—C16—H16B | 109.5 |
C5—O5—H5 | 108 (2) | C14—C16—H16C | 109.5 |
C7—C6—C5 | 121.37 (19) | H16A—C16—H16C | 109.5 |
C7—C6—H6 | 119.3 | H16B—C16—H16C | 109.5 |
C5—C6—H6 | 119.3 | O17—C17—O11 | 123.4 (2) |
C6—C7—C8 | 119.01 (19) | O17—C17—C18 | 124.3 (2) |
C6—C7—C11 | 123.53 (18) | O11—C17—C18 | 112.29 (18) |
C8—C7—C11 | 117.46 (18) | C19—C18—C17 | 124.1 (2) |
O8—C8—C9 | 122.29 (18) | C19—C18—H18 | 117.9 |
O8—C8—C7 | 117.28 (18) | C17—C18—H18 | 117.9 |
C9—C8—C7 | 120.43 (19) | C18—C19—C20 | 126.9 (2) |
C8—O8—H8 | 106 (2) | C18—C19—H19 | 116.5 |
C8—C9—C10 | 119.70 (18) | C20—C19—H19 | 116.5 |
C8—C9—C1 | 120.14 (19) | C25—C20—C21 | 119.2 (2) |
C10—C9—C1 | 120.15 (19) | C25—C20—C19 | 119.09 (19) |
C5—C10—C9 | 119.44 (18) | C21—C20—C19 | 121.7 (2) |
C5—C10—C4 | 120.37 (19) | C22—C21—C20 | 119.6 (2) |
C9—C10—C4 | 120.19 (18) | C22—C21—H21 | 120.2 |
O11—C11—C7 | 106.56 (16) | C20—C21—H21 | 120.2 |
O11—C11—C12 | 109.04 (16) | C21—C22—C23 | 120.7 (2) |
C7—C11—C12 | 113.88 (18) | C21—C22—H22 | 119.7 |
O11—C11—H11 | 109.1 | C23—C22—H22 | 119.7 |
C7—C11—H11 | 109.1 | C22—C23—C24 | 120.2 (2) |
C12—C11—H11 | 109.1 | C22—C23—H23 | 119.9 |
C17—O11—C11 | 116.98 (16) | C24—C23—H23 | 119.9 |
C13—C12—C11 | 114.42 (18) | C23—C24—C25 | 119.6 (2) |
C13—C12—H12A | 108.7 | C23—C24—H24 | 120.2 |
C11—C12—H12A | 108.7 | C25—C24—H24 | 120.2 |
C13—C12—H12B | 108.7 | C20—C25—C24 | 120.7 (2) |
C11—C12—H12B | 108.7 | C20—C25—H25 | 119.6 |
H12A—C12—H12B | 107.6 | C24—C25—H25 | 119.6 |
O1—C1—C2—C3 | −179.0 (2) | C3—C4—C10—C9 | −1.3 (3) |
C9—C1—C2—C3 | −0.3 (3) | C6—C7—C11—O11 | 14.0 (3) |
C1—C2—C3—C4 | −1.7 (3) | C8—C7—C11—O11 | −165.76 (17) |
C2—C3—C4—O4 | −177.8 (2) | C6—C7—C11—C12 | −106.3 (2) |
C2—C3—C4—C10 | 2.4 (3) | C8—C7—C11—C12 | 74.0 (2) |
O5—C5—C6—C7 | 178.7 (2) | C7—C11—O11—C17 | 148.35 (17) |
C10—C5—C6—C7 | −0.9 (3) | C12—C11—O11—C17 | −88.3 (2) |
C5—C6—C7—C8 | 0.3 (3) | O11—C11—C12—C13 | −59.5 (2) |
C5—C6—C7—C11 | −179.47 (19) | C7—C11—C12—C13 | 59.3 (2) |
C6—C7—C8—O8 | 179.60 (19) | C11—C12—C13—C14 | 148.8 (2) |
C11—C7—C8—O8 | −0.7 (3) | C12—C13—C14—C16 | −0.8 (4) |
C6—C7—C8—C9 | 0.3 (3) | C12—C13—C14—C15 | 179.4 (2) |
C11—C7—C8—C9 | −179.92 (19) | C11—O11—C17—O17 | −1.9 (3) |
O8—C8—C9—C10 | −179.47 (19) | C11—O11—C17—C18 | 176.89 (18) |
C7—C8—C9—C10 | −0.2 (3) | O17—C17—C18—C19 | −169.2 (2) |
O8—C8—C9—C1 | 0.4 (3) | O11—C17—C18—C19 | 12.0 (3) |
C7—C8—C9—C1 | 179.65 (19) | C17—C18—C19—C20 | −175.6 (2) |
O1—C1—C9—C8 | 0.2 (3) | C18—C19—C20—C25 | −168.2 (2) |
C2—C1—C9—C8 | −178.53 (19) | C18—C19—C20—C21 | 14.8 (3) |
O1—C1—C9—C10 | −179.9 (2) | C25—C20—C21—C22 | −0.8 (3) |
C2—C1—C9—C10 | 1.4 (3) | C19—C20—C21—C22 | 176.2 (2) |
O5—C5—C10—C9 | −178.60 (19) | C20—C21—C22—C23 | 0.6 (3) |
C6—C5—C10—C9 | 1.0 (3) | C21—C22—C23—C24 | 0.3 (4) |
O5—C5—C10—C4 | 1.6 (3) | C22—C23—C24—C25 | −0.9 (4) |
C6—C5—C10—C4 | −178.74 (19) | C21—C20—C25—C24 | 0.1 (3) |
C8—C9—C10—C5 | −0.4 (3) | C19—C20—C25—C24 | −176.9 (2) |
C1—C9—C10—C5 | 179.7 (2) | C23—C24—C25—C20 | 0.7 (4) |
C8—C9—C10—C4 | 179.33 (19) | C6—C7—C11—C12 | −106.3 (2) |
C1—C9—C10—C4 | −0.6 (3) | C7—C11—C12—C13 | 59.3 (2) |
O4—C4—C10—C5 | −1.3 (3) | C11—C12—C13—C14 | 148.8 (2) |
C3—C4—C10—C5 | 178.50 (19) | C12—C13—C14—C15 | 179.4 (2) |
O4—C4—C10—C9 | 178.93 (19) | C12—C13—C14—C16 | −0.8 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H5···O4 | 0.87 (3) | 1.81 (3) | 2.587 (2) | 148 (3) |
O8—H8···O1 | 0.88 (4) | 1.79 (3) | 2.589 (2) | 150 (3) |
C3—H3···O17i | 0.93 | 2.47 | 3.356 (3) | 160 |
C11—H11···O5ii | 0.98 | 2.56 | 3.359 (3) | 138 |
C16—H16A···O1iii | 0.96 | 2.72 | 3.631 (3) | 159 |
C21—H21···O4iv | 0.93 | 2.62 | 3.538 (3) | 170 |
Symmetry codes: (i) x+1, y, z−1; (ii) x−1, y, z; (iii) x, y, z+1; (iv) x−1, y, z+1. |
Experimental details
Crystal data | |
Chemical formula | C25H22O6 |
Mr | 418.43 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 100 |
a, b, c (Å) | 6.1677 (1), 15.7416 (3), 10.5141 (2) |
β (°) | 90.763 (1) |
V (Å3) | 1020.72 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.5 × 0.1 × 0.1 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | ψ-scan (XPREP; Sheldrick, 1994) |
Tmin, Tmax | 0.885, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7463, 4357, 4011 |
Rint | 0.028 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.096, 1.09 |
No. of reflections | 4357 |
No. of parameters | 290 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.25, −0.25 |
Computer programs: SMART (Bruker, 1998), SMART, SAINT (Bruker, 1998), SHELXS86 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), NRCVAX (Gabe et al., 1989), ORTEP (Johnson, 1965) and PLUTO (Motherwell & Clegg, 1978), SHELXL97.
C9—C1—C2—C3 | −0.3 (3) | C3—C4—C10—C9 | −1.3 (3) |
C1—C2—C3—C4 | −1.7 (3) | C7—C11—O11—C17 | 148.35 (17) |
C2—C3—C4—C10 | 2.4 (3) | C11—O11—C17—C18 | 176.89 (18) |
C10—C5—C6—C7 | −0.9 (3) | O11—C17—C18—C19 | 12.0 (3) |
C5—C6—C7—C8 | 0.3 (3) | C17—C18—C19—C20 | −175.6 (2) |
C6—C7—C8—C9 | 0.3 (3) | C25—C20—C21—C22 | −0.8 (3) |
C7—C8—C9—C10 | −0.2 (3) | C20—C21—C22—C23 | 0.6 (3) |
C2—C1—C9—C10 | 1.4 (3) | C21—C22—C23—C24 | 0.3 (4) |
C6—C5—C10—C9 | 1.0 (3) | C22—C23—C24—C25 | −0.9 (4) |
C8—C9—C10—C5 | −0.4 (3) | C21—C20—C25—C24 | 0.1 (3) |
C1—C9—C10—C4 | −0.6 (3) | C23—C24—C25—C20 | 0.7 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O5—H5···O4 | 0.87 (3) | 1.81 (3) | 2.587 (2) | 148 (3) |
O8—H8···O1 | 0.88 (4) | 1.79 (3) | 2.589 (2) | 150 (3) |
C3—H3···O17i | 0.93 | 2.469 | 3.356 (3) | 160 |
C11—H11···O5ii | 0.98 | 2.564 | 3.359 (3) | 138 |
C16—H16A···O1iii | 0.96 | 2.719 | 3.631 (3) | 159 |
C21—H21···O4iv | 0.93 | 2.619 | 3.538 (3) | 170 |
Symmetry codes: (i) x+1, y, z−1; (ii) x−1, y, z; (iii) x, y, z+1; (iv) x−1, y, z+1. |
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Arnebin-1 (β,β-dimethyl acryloyl shikonin), a naturally occurring naphthoquinone from the root of the plant Arnebia nobilis, belongs to the alkanin/shikonin family (Shukla et al., 1969). The toxic effects of this compound restricted its further development as a clinically useful therapeutic agent, in spite of its wound healing, antiinflammatory, antithrombotic, antimicrobial and anticancer activities (Papageorgiou et al., 1999). This necessitated the development of numerous analogues of shikonin with greatly reduced toxicity. One such analogue is the title compound, (I), which shows a growth-inhibiting effect on prostate cancer cells (Gaddipati et al., 2000). This prompted us to undertake the present diffraction study in order to confirm the overall three-dimensional structure of (I). \sch
The conformation of (I) and the atom-numbering scheme are shown in Fig. 1. The molecule contains one naphthaquinone ring (fused ring system A/B), to which a phenyl ring (C) is attached via an ester bond, and one chiral centre (C11). Although the present study does not establish the absolute configuration of the molecule [Flack (1983) parameter 0.3 (9)], the parent shikonin has the R configuration, as determined by the chemical degradation method (Arakawa & Nakazaki, 1961). The phenyl ring C is almost parallel with the A/B ring: the interplanar angle between the two rings is 1.7 (1)°. Moreover, the phenyl ring at C19 is anti to the carbonyl group at C17 [C17—C18—C19—C20 - 175.6 (2)°].
The molecule of (I) contains two potential hydrogen-bond donors (–OH groups O5—H5 and O8—H8), which are involved in intramolecular hydrogen-bonding interactions with carbonyl groups C4═O4 and C1═O1 (Table 2) through the formation of six-membered rings (Fig. 1). The formation of such rings is preferred over intermolecular hydrogen bonding (Bilton et al. 2000). The strong intramolecular O···O distances observed in (I) are in the same range as those found in the parent naphthazarin C at 60 K (Herbstein et al. 1985).
The hydroxyl H atoms, H5 and H8, were located in a difference Fourier map, in view of the ambiguity about their positions in related naphthazarin systems (Herbstein et al. 1985). A comparison of bond lengths in (I) with those of naphthazarin C (neutron diffraction at 60 K) and other related systems (Herbstein et al., 1985, and references therein) shows that, on average, C═O is ca 0.05 Å longer (in which molecule?), while C—OH is ca 0.03 Å shorter (in which molecule?). This suggests that, in close analogy with the crystal structure of naphthazarin C, the hydroxyl H atoms are not completely localized in (I) at 100 K and that ordering will be favoured at lower temperatures, since a complete localization is only possible at 0 K.
In addition, weak hydrogen-bonding interactions of the type C—H···O are also observed (Table 2). The crystal packing (Fig. 2) further shows that the phenyl ring C stacks with the benzoquinone ring A, due to aromatic π-π interactions. The average intermolecular stacking distance and the angle between the rings, which overlap substantially in a `face-to-face' orientation as per the model proposed by Hunter (1990), are 3.3 Å and 1.1 (1)°, respectively. The benzoquinone ring being electron deficient, it can allow for a substantial face-to-face overlap with the relatively neutral phenyl ring without much π-π repulsion.