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In order to study structure-activity relationships, a series of mono-, di- and trioxygenated xanthones has been synthesized and the structures of methyl 2-(3,4-dimethoxyphenoxy)benzoate, C16H16O5, 2-(3,4-dimethoxyphenoxy)benzoic acid, C15H14O5, 1,2-dimethoxy-9H-xanthen-9-one, C15H12O4, and 1,2,8-trimethoxy-9H-xanthen-9-one, C16H14O5, have been determined. The first two compounds both assume skew conformations, the dihedral angles between the two phenyl rings being 80.04 (8) and 83.0 (1)°, respectively. The latter two compounds are essentially planar and their methoxy substituents assume orientations consistent with minimum steric interactions.
Supporting information
CCDC references: 175090; 175091; 175092; 175093
The synthesis of (I) [step (1) in the Scheme] was carried out according to the
method of Fernandes et al. (1995). A mixture of 2-bromobenzoic acid
methyl ester (16.2 g, 75 mmol), 3,4-dimethoxyphenol (11.9 g, 77 mmol), copper
bronze (9.8 g, 155 mmol) and Na2CO3 (21.3 g, 154 mmol) in dry pyridine
(240 ml) was thoroughly degassed with nitrogen and refluxed for 26 h. The
mixture was then cooled to room temperature, filtered and concentrated,
furnishing a dark-brown oily liquid which was dissolved in methylene chloride
and then washed with 0.5 N NaOH. The organic layer was dried over Na2SO4,
filtered and concentrated under reduced presssure to provide an oily brown
liquid (18.2 g). This was purified by column chromatography [petroleum ether
(313–333 K boiling fraction)/diethyl ether (5:5)]. Evaporation of the solvent
under reduced pressure furnished a solid product, (I) (9.0 g, 41%), which was
crystallized from a mixture of diethyl ether/n-hexane.
The synthesis of (II) [step (2) in the Scheme] was carried out according to the
method of Fernandes et al. (1995). Compound (I) (8.2 g, 28 mmol) was
dissolved in methanol/tetrahydrofuran (1:1) and treated with aqueous 5 N NaOH
solution (12 ml) at room temperature for 96 h. The crude product was washed
with ether, and the aqueous layer was separated, washed with methylene
chloride, acidified with 5 N HCl and extracted with methylene chloride. The
organic phase was dried over Na2SO4, filtered and concentrated under
reduced pressure, furnishing a white solid, (II) (7.6 g, 98%), which was
crystallized from methylene chloride.
The synthesis of (III) [step (3) in the Scheme] was carried out according to
the method of Fernandes et al. (1995). To a 2M solution of LDA
(please define LDA) in tetrahydrofuran/heptane/ethylbenzene (2.5 ml, 5 mmol,
ratio of solvents?), a solution of (II) (2.688 mg, 2.5 mmol) in dry
tetrahydrofuran (25 ml) was added dropwise over 1 h at 273 K under a nitrogen
atmosphere. The reaction mixture was allowed to reach room temperature over 1 h. The reaction was quenched by addition of 5% HCl and then extracted with
methylene chloride. The organic phase was washed with 5% Na2CO3, dried
over Na2SO4, filtered and concentrated under reduced pressure, to furnish
an oily brown liquid. This crude product was purified by column chromatography
[chloroform/n-hexane (7:3)]. After evaporation of the solvent, the solid,
(III) (476.3 mg, 74%), was crystallized from a mixture of methylene
chloride/n-hexane.
Compound (IV) was isolated from the wood of Callophyllum teysmanii var.
inophylloide, using the method of Kijjoa et al. (2000).
All H atoms in (I), H5 and H6 in (II), H4 and H8 in (III) and the aromatic H
atoms in (IV) were located from difference Fourier maps and refined freely
with isotropic displacement parameters. The remaining H atoms could not be
clearly located from the difference maps, and were placed geometrically and
refined riding on their parent C atoms at distances of 0.93 Å (aromatic) and
0.96 Å (methyl), with Uiso(H) = xUeq(C), where x =
1.2 and 1.5, respectively. A degree of racemic twinning was indicated for
compound (IV) and a twin correction with two equal components was applied.
This improved the refinement marginally.
For all compounds, data collection: IPDS (Stoe & Cie, 1994); cell refinement: IPDS; data reduction: IPDS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 and ORTEP-3.
(I) Methyl 2-(3,4-dimethoxyphenoxy)benzoate
top
Crystal data top
C16H16O5 | Dx = 1.322 Mg m−3 |
Mr = 288.29 | Melting point = 335–336 K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71069 Å |
a = 15.306 (7) Å | Cell parameters from 1232 reflections |
b = 7.788 (4) Å | θ = 5.0–28.1° |
c = 16.426 (7) Å | µ = 0.10 mm−1 |
β = 132.31 (3)° | T = 293 K |
V = 1448.0 (12) Å3 | Square prism, colourless |
Z = 4 | 0.30 × 0.25 × 0.20 mm |
F(000) = 608 | |
Data collection top
Stoe IPDS diffractometer | 2221 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.068 |
Graphite monochromator | θmax = 28.1°, θmin = 5.0° |
Image Plate scans | h = −20→19 |
13194 measured reflections | k = −10→10 |
3439 independent reflections | l = −21→21 |
Refinement top
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.165 | All H-atom parameters refined |
S = 1.05 | w = 1/[σ2(Fo2) + (0.068P)2 + 0.376P] where P = (Fo2 + 2Fc2)/3 |
3439 reflections | (Δ/σ)max < 0.001 |
254 parameters | Δρmax = 0.23 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
Crystal data top
C16H16O5 | V = 1448.0 (12) Å3 |
Mr = 288.29 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 15.306 (7) Å | µ = 0.10 mm−1 |
b = 7.788 (4) Å | T = 293 K |
c = 16.426 (7) Å | 0.30 × 0.25 × 0.20 mm |
β = 132.31 (3)° | |
Data collection top
Stoe IPDS diffractometer | 2221 reflections with I > 2σ(I) |
13194 measured reflections | Rint = 0.068 |
3439 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.165 | All H-atom parameters refined |
S = 1.05 | Δρmax = 0.23 e Å−3 |
3439 reflections | Δρmin = −0.22 e Å−3 |
254 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 | x | y | z | Uiso*/Ueq | |
O1 | 0.24922 (13) | 0.95469 (19) | 0.36254 (10) | 0.0701 (5) | |
O2 | 0.52741 (18) | 1.1418 (3) | 0.67270 (13) | 0.1062 (8) | |
O3 | 0.43905 (15) | 0.9146 (2) | 0.56698 (12) | 0.0799 (5) | |
O4 | 0.08949 (12) | 0.7792 (2) | 0.00103 (11) | 0.0648 (4) | |
O5 | −0.10491 (12) | 0.6765 (2) | −0.05112 (10) | 0.0647 (4) | |
C1 | 0.27071 (16) | 1.1278 (3) | 0.37561 (14) | 0.0511 (4) | |
C2 | 0.36879 (16) | 1.1880 (3) | 0.48176 (15) | 0.0532 (4) | |
C3 | 0.3895 (2) | 1.3644 (3) | 0.49603 (19) | 0.0668 (6) | |
C4 | 0.3174 (2) | 1.4790 (3) | 0.4103 (2) | 0.0730 (6) | |
C5 | 0.2212 (2) | 1.4168 (3) | 0.30683 (19) | 0.0649 (5) | |
C6 | 0.19786 (18) | 1.2434 (3) | 0.28934 (16) | 0.0563 (5) | |
C1' | 0.15623 (18) | 0.8911 (3) | 0.25623 (14) | 0.0586 (5) | |
C2' | 0.17351 (18) | 0.8712 (3) | 0.18365 (15) | 0.0575 (5) | |
C3' | 0.08389 (16) | 0.8010 (2) | 0.08024 (14) | 0.0522 (4) | |
C4' | −0.02158 (16) | 0.7463 (3) | 0.05170 (14) | 0.0534 (5) | |
C5' | −0.03561 (19) | 0.7676 (3) | 0.12593 (16) | 0.0616 (5) | |
C6' | 0.0536 (2) | 0.8416 (3) | 0.22907 (16) | 0.0636 (5) | |
C7 | 0.45267 (17) | 1.0809 (3) | 0.58277 (15) | 0.0580 (5) | |
C8 | 0.1928 (3) | 0.8416 (4) | 0.0255 (3) | 0.0776 (7) | |
C9 | −0.2103 (2) | 0.6147 (4) | −0.0804 (2) | 0.0687 (6) | |
C10 | 0.5178 (3) | 0.8075 (5) | 0.6633 (2) | 0.0852 (8) | |
H3 | 0.460 (2) | 1.401 (3) | 0.572 (2) | 0.079 (7)* | |
H4 | 0.336 (2) | 1.602 (4) | 0.424 (2) | 0.088 (8)* | |
H5 | 0.167 (2) | 1.495 (3) | 0.246 (2) | 0.075 (7)* | |
H6 | 0.134 (2) | 1.201 (3) | 0.2192 (19) | 0.067 (6)* | |
H2' | 0.244 (2) | 0.902 (3) | 0.2046 (18) | 0.066 (6)* | |
H5' | −0.108 (2) | 0.731 (3) | 0.105 (2) | 0.073 (7)* | |
H6' | 0.044 (2) | 0.854 (3) | 0.2804 (19) | 0.072 (6)* | |
H8A | −0.252 (2) | 0.556 (3) | −0.151 (2) | 0.086 (8)* | |
H8B | −0.254 (2) | 0.715 (4) | −0.084 (2) | 0.079 (7)* | |
H8C | −0.190 (2) | 0.531 (3) | −0.025 (2) | 0.074 (7)* | |
H9A | 0.181 (3) | 0.818 (4) | −0.040 (3) | 0.110 (10)* | |
H9B | 0.262 (3) | 0.777 (4) | 0.091 (2) | 0.092 (9)* | |
H9C | 0.205 (3) | 0.969 (4) | 0.042 (2) | 0.096 (9)* | |
H10A | 0.505 (4) | 0.841 (6) | 0.710 (3) | 0.153 (16)* | |
H10B | 0.594 (4) | 0.830 (5) | 0.699 (3) | 0.133 (13)* | |
H10C | 0.494 (4) | 0.694 (6) | 0.640 (3) | 0.156 (16)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0700 (9) | 0.0592 (9) | 0.0393 (7) | −0.0049 (7) | 0.0198 (7) | −0.0001 (6) |
O2 | 0.0953 (14) | 0.0945 (14) | 0.0488 (9) | 0.0103 (10) | 0.0160 (9) | −0.0106 (8) |
O3 | 0.0726 (10) | 0.0693 (10) | 0.0459 (7) | 0.0002 (8) | 0.0188 (7) | 0.0077 (7) |
O4 | 0.0586 (8) | 0.0822 (10) | 0.0578 (8) | −0.0099 (7) | 0.0409 (7) | −0.0071 (7) |
O5 | 0.0508 (7) | 0.0875 (10) | 0.0450 (7) | −0.0137 (7) | 0.0279 (6) | −0.0088 (7) |
C1 | 0.0484 (9) | 0.0586 (11) | 0.0441 (9) | 0.0014 (8) | 0.0302 (8) | −0.0011 (8) |
C2 | 0.0470 (9) | 0.0632 (11) | 0.0480 (9) | 0.0010 (8) | 0.0315 (8) | −0.0019 (8) |
C3 | 0.0608 (12) | 0.0680 (13) | 0.0596 (12) | −0.0046 (10) | 0.0356 (10) | −0.0085 (10) |
C4 | 0.0787 (15) | 0.0574 (13) | 0.0778 (15) | −0.0022 (11) | 0.0505 (13) | −0.0036 (11) |
C5 | 0.0685 (13) | 0.0639 (13) | 0.0645 (12) | 0.0128 (10) | 0.0457 (11) | 0.0107 (10) |
C6 | 0.0533 (10) | 0.0653 (12) | 0.0465 (10) | 0.0054 (9) | 0.0320 (9) | 0.0041 (8) |
C1' | 0.0565 (11) | 0.0567 (11) | 0.0392 (9) | 0.0012 (8) | 0.0227 (8) | 0.0024 (7) |
C2' | 0.0466 (10) | 0.0581 (11) | 0.0510 (10) | −0.0022 (8) | 0.0260 (8) | 0.0031 (8) |
C3' | 0.0499 (9) | 0.0553 (10) | 0.0441 (9) | 0.0015 (8) | 0.0286 (8) | 0.0021 (7) |
C4' | 0.0468 (9) | 0.0608 (11) | 0.0409 (9) | −0.0004 (8) | 0.0248 (8) | 0.0015 (8) |
C5' | 0.0514 (11) | 0.0782 (14) | 0.0503 (10) | −0.0023 (10) | 0.0323 (9) | 0.0017 (9) |
C6' | 0.0650 (12) | 0.0744 (14) | 0.0472 (10) | 0.0019 (10) | 0.0361 (10) | 0.0020 (9) |
C7 | 0.0469 (9) | 0.0748 (13) | 0.0436 (9) | 0.0021 (9) | 0.0269 (8) | −0.0064 (9) |
C8 | 0.0762 (16) | 0.0856 (19) | 0.0892 (18) | −0.0148 (14) | 0.0630 (15) | −0.0064 (15) |
C9 | 0.0535 (11) | 0.0801 (16) | 0.0600 (13) | −0.0126 (11) | 0.0331 (10) | −0.0059 (12) |
C10 | 0.0695 (16) | 0.088 (2) | 0.0566 (13) | 0.0065 (14) | 0.0256 (12) | 0.0197 (13) |
Geometric parameters (Å, º) top
O1—C1 | 1.370 (3) | C1—C2 | 1.411 (3) |
O1—C1' | 1.405 (2) | C2—C3 | 1.394 (3) |
O4—C3' | 1.371 (2) | C2—C7 | 1.493 (3) |
O4—C8 | 1.429 (3) | C3—C4 | 1.380 (3) |
O5—C4' | 1.369 (2) | C3—H3 | 1.00 (3) |
O5—C9 | 1.422 (3) | C4—C5 | 1.387 (3) |
O2—C7 | 1.200 (2) | C4—H4 | 0.98 (3) |
O3—C7 | 1.310 (3) | C5—C6 | 1.377 (3) |
O3—C10 | 1.444 (3) | C5—H5 | 0.97 (3) |
C1'—C6' | 1.368 (3) | C6—H6 | 0.93 (2) |
C1'—C2' | 1.393 (3) | C8—H9A | 0.98 (3) |
C2'—C3' | 1.389 (3) | C8—H9B | 1.00 (3) |
C2'—H2' | 0.92 (2) | C8—H9C | 1.02 (3) |
C3'—C4' | 1.410 (3) | C9—H8A | 0.99 (3) |
C4'—C5' | 1.383 (3) | C9—H8B | 1.00 (3) |
C5'—C6' | 1.397 (3) | C9—H8C | 0.98 (3) |
C5'—H5' | 0.96 (3) | C10—H10A | 0.94 (4) |
C6'—H6' | 0.96 (3) | C10—H10B | 0.90 (4) |
C1—C6 | 1.391 (3) | C10—H10C | 0.93 (5) |
| | | |
C1—O1—C1' | 118.49 (15) | C3—C4—C5 | 119.0 (2) |
C3'—O4—C8 | 117.06 (18) | C3—C4—H4 | 119.0 (16) |
C4'—O5—C9 | 117.00 (17) | C5—C4—H4 | 122.0 (16) |
C7—O3—C10 | 116.7 (2) | C6—C5—C4 | 120.7 (2) |
C6'—C1'—C2' | 121.82 (18) | C6—C5—H5 | 118.6 (15) |
C6'—C1'—O1 | 119.00 (19) | C4—C5—H5 | 120.7 (15) |
C2'—C1'—O1 | 119.07 (19) | C5—C6—C1 | 120.3 (2) |
C3'—C2'—C1' | 119.4 (2) | C5—C6—H6 | 120.7 (14) |
C3'—C2'—H2' | 120.3 (14) | C1—C6—H6 | 119.0 (14) |
C1'—C2'—H2' | 120.3 (14) | O4—C8—H9A | 106.1 (19) |
O4—C3'—C2' | 124.63 (18) | O4—C8—H9B | 107.9 (17) |
O4—C3'—C4' | 115.85 (16) | H9A—C8—H9B | 111 (2) |
C2'—C3'—C4' | 119.52 (18) | O4—C8—H9C | 112.0 (17) |
O5—C4'—C5' | 124.52 (18) | H9A—C8—H9C | 110 (2) |
O5—C4'—C3' | 115.94 (17) | H9B—C8—H9C | 109 (2) |
C5'—C4'—C3' | 119.54 (18) | O5—C9—H8A | 104.1 (16) |
C4'—C5'—C6' | 120.9 (2) | O5—C9—H8B | 108.6 (15) |
C4'—C5'—H5' | 118.5 (14) | H8A—C9—H8B | 114 (2) |
C6'—C5'—H5' | 120.6 (14) | O5—C9—H8C | 109.6 (15) |
C1'—C6'—C5' | 118.8 (2) | H8A—C9—H8C | 110 (2) |
C1'—C6'—H6' | 120.8 (14) | H8B—C9—H8C | 110 (2) |
C5'—C6'—H6' | 120.3 (14) | O2—C7—O3 | 121.8 (2) |
O1—C1—C6 | 122.28 (17) | O2—C7—C2 | 122.8 (2) |
O1—C1—C2 | 117.67 (16) | O3—C7—C2 | 115.42 (16) |
C6—C1—C2 | 120.03 (19) | O3—C10—H10A | 105 (3) |
C3—C2—C1 | 117.90 (18) | O3—C10—H10B | 111 (2) |
C3—C2—C7 | 115.82 (18) | H10A—C10—H10B | 107 (4) |
C1—C2—C7 | 126.26 (19) | O3—C10—H10C | 107 (3) |
C4—C3—C2 | 122.0 (2) | H10A—C10—H10C | 111 (4) |
C4—C3—H3 | 122.7 (15) | H10B—C10—H10C | 115 (4) |
C2—C3—H3 | 115.3 (15) | | |
(II) 2-(3,4-Dimethoxyphenoxy)benzoic acid
top
Crystal data top
C15H14O5 | F(000) = 288 |
Mr = 274.26 | Dx = 1.356 Mg m−3 |
Triclinic, P1 | Melting point = 420–422 K |
a = 7.920 (4) Å | Mo Kα radiation, λ = 0.71069 Å |
b = 8.550 (5) Å | Cell parameters from 854 reflections |
c = 11.360 (7) Å | θ = 4.7–24.2° |
α = 76.02 (7)° | µ = 0.10 mm−1 |
β = 82.46 (7)° | T = 293 K |
γ = 64.20 (6)° | Rectangular prism, colourless |
V = 671.8 (7) Å3 | 0.7 × 0.4 × 0.3 mm |
Z = 2 | |
Data collection top
Stoe IPDS diffractometer | 1618 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.047 |
Graphite monochromator | θmax = 24.1°, θmin = 4.7° |
Image Plate scans | h = −9→8 |
4584 measured reflections | k = −9→9 |
1923 independent reflections | l = −12→12 |
Refinement top
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)] = 0.050 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.159 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.098P)2 + 0.065P] where P = (Fo2 + 2Fc2)/3 |
1923 reflections | (Δ/σ)max = 0.001 |
189 parameters | Δρmax = 0.14 e Å−3 |
0 restraints | Δρmin = −0.15 e Å−3 |
Crystal data top
C15H14O5 | γ = 64.20 (6)° |
Mr = 274.26 | V = 671.8 (7) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.920 (4) Å | Mo Kα radiation |
b = 8.550 (5) Å | µ = 0.10 mm−1 |
c = 11.360 (7) Å | T = 293 K |
α = 76.02 (7)° | 0.7 × 0.4 × 0.3 mm |
β = 82.46 (7)° | |
Data collection top
Stoe IPDS diffractometer | 1618 reflections with I > 2σ(I) |
4584 measured reflections | Rint = 0.047 |
1923 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.050 | 0 restraints |
wR(F2) = 0.159 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.14 e Å−3 |
1923 reflections | Δρmin = −0.15 e Å−3 |
189 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 | x | y | z | Uiso*/Ueq | |
O1 | 0.25935 (19) | 0.52786 (18) | 0.28297 (15) | 0.0871 (5) | |
O2 | 0.4304 (2) | 0.2115 (2) | 0.41975 (16) | 0.0960 (6) | |
O3 | 0.2642 (2) | 0.05641 (19) | 0.49096 (16) | 0.0931 (6) | |
H3 | 0.3679 | −0.0181 | 0.5146 | 0.140* | |
O4 | 0.2559 (2) | 0.91095 (18) | −0.10998 (11) | 0.0805 (5) | |
O5 | 0.2565 (2) | 1.14851 (18) | −0.00850 (13) | 0.0818 (5) | |
C1 | 0.0937 (3) | 0.5098 (2) | 0.31241 (16) | 0.0662 (5) | |
C2 | 0.1019 (3) | 0.3482 (2) | 0.38412 (15) | 0.0633 (5) | |
C3 | −0.0656 (3) | 0.3280 (3) | 0.41072 (17) | 0.0736 (6) | |
H3A | −0.0624 | 0.2209 | 0.4569 | 0.088* | |
C4 | −0.2344 (3) | 0.4611 (3) | 0.3708 (2) | 0.0801 (6) | |
H4 | −0.3443 | 0.4449 | 0.3898 | 0.096* | |
C5 | −0.2392 (3) | 0.6200 (3) | 0.3017 (2) | 0.0786 (6) | |
H5 | −0.354 (4) | 0.709 (3) | 0.270 (2) | 0.089 (6)* | |
C6 | −0.0778 (3) | 0.6457 (3) | 0.27240 (18) | 0.0739 (6) | |
H6 | −0.082 (3) | 0.755 (3) | 0.223 (2) | 0.079 (6)* | |
C1' | 0.2517 (3) | 0.6894 (3) | 0.21153 (19) | 0.0718 (6) | |
C2' | 0.2543 (3) | 0.7141 (2) | 0.08560 (18) | 0.0704 (6) | |
H2' | 0.2557 | 0.6265 | 0.0498 | 0.085* | |
C3' | 0.2548 (3) | 0.8701 (2) | 0.01435 (16) | 0.0645 (5) | |
C4' | 0.2555 (3) | 1.0000 (2) | 0.06998 (17) | 0.0644 (5) | |
C5' | 0.2544 (3) | 0.9711 (3) | 0.19456 (18) | 0.0731 (6) | |
H5' | 0.2548 | 1.0572 | 0.2312 | 0.088* | |
C6' | 0.2527 (3) | 0.8147 (3) | 0.26675 (17) | 0.0757 (6) | |
H6' | 0.2522 | 0.7958 | 0.3509 | 0.091* | |
C7 | 0.2768 (3) | 0.1981 (2) | 0.43362 (15) | 0.0662 (5) | |
C8 | 0.2560 (3) | 0.7846 (3) | −0.1720 (2) | 0.0867 (7) | |
H8A | 0.2564 | 0.8300 | −0.2579 | 0.130* | |
H8B | 0.1459 | 0.7631 | −0.1479 | 0.130* | |
H8C | 0.3659 | 0.6755 | −0.1518 | 0.130* | |
C9 | 0.2548 (4) | 1.2853 (3) | 0.0412 (2) | 0.0920 (7) | |
H9A | 0.2560 | 1.3810 | −0.0233 | 0.138* | |
H9B | 0.3636 | 1.2402 | 0.0892 | 0.138* | |
H9C | 0.1437 | 1.3277 | 0.0913 | 0.138* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0685 (8) | 0.0683 (9) | 0.1013 (10) | −0.0262 (7) | −0.0054 (7) | 0.0201 (7) |
O2 | 0.0748 (9) | 0.0744 (10) | 0.1130 (12) | −0.0262 (7) | −0.0031 (8) | 0.0168 (8) |
O3 | 0.0889 (10) | 0.0682 (9) | 0.1075 (12) | −0.0331 (7) | −0.0163 (8) | 0.0155 (8) |
O4 | 0.1120 (11) | 0.0721 (8) | 0.0622 (8) | −0.0446 (8) | 0.0002 (7) | −0.0121 (6) |
O5 | 0.1122 (11) | 0.0623 (8) | 0.0762 (9) | −0.0453 (7) | −0.0060 (7) | −0.0049 (6) |
C1 | 0.0688 (11) | 0.0651 (10) | 0.0585 (10) | −0.0270 (9) | 0.0032 (8) | −0.0066 (8) |
C2 | 0.0727 (11) | 0.0606 (10) | 0.0512 (9) | −0.0260 (8) | 0.0031 (7) | −0.0085 (7) |
C3 | 0.0829 (13) | 0.0700 (12) | 0.0662 (11) | −0.0347 (10) | 0.0049 (9) | −0.0098 (9) |
C4 | 0.0702 (12) | 0.0863 (14) | 0.0822 (13) | −0.0343 (10) | 0.0029 (10) | −0.0146 (11) |
C5 | 0.0685 (12) | 0.0785 (13) | 0.0776 (12) | −0.0235 (10) | −0.0064 (9) | −0.0084 (10) |
C6 | 0.0738 (12) | 0.0655 (11) | 0.0705 (11) | −0.0242 (9) | −0.0048 (9) | −0.0012 (9) |
C1' | 0.0612 (10) | 0.0615 (10) | 0.0773 (12) | −0.0229 (8) | −0.0021 (8) | 0.0076 (9) |
C2' | 0.0740 (11) | 0.0551 (10) | 0.0777 (12) | −0.0262 (8) | 0.0001 (9) | −0.0085 (8) |
C3' | 0.0680 (10) | 0.0577 (10) | 0.0615 (10) | −0.0242 (8) | 0.0016 (8) | −0.0075 (8) |
C4' | 0.0682 (10) | 0.0552 (9) | 0.0660 (10) | −0.0256 (8) | −0.0005 (8) | −0.0069 (8) |
C5' | 0.0785 (12) | 0.0719 (12) | 0.0687 (11) | −0.0310 (10) | −0.0014 (9) | −0.0157 (9) |
C6' | 0.0753 (12) | 0.0817 (13) | 0.0608 (10) | −0.0300 (10) | −0.0016 (9) | −0.0039 (9) |
C7 | 0.0777 (12) | 0.0599 (10) | 0.0545 (9) | −0.0278 (9) | 0.0041 (8) | −0.0053 (8) |
C8 | 0.0982 (15) | 0.0931 (15) | 0.0790 (13) | −0.0444 (12) | 0.0063 (11) | −0.0323 (11) |
C9 | 0.1114 (17) | 0.0695 (13) | 0.1067 (17) | −0.0490 (12) | −0.0016 (13) | −0.0180 (12) |
Geometric parameters (Å, º) top
O1—C1 | 1.376 (2) | C2'—C1' | 1.393 (3) |
O1—C1' | 1.403 (2) | C2'—H2' | 0.9300 |
O2—C7 | 1.257 (3) | C1'—C6' | 1.369 (3) |
O3—C7 | 1.268 (2) | C5—C4 | 1.382 (3) |
O3—H3 | 0.8200 | C5—H5 | 0.94 (3) |
O4—C3' | 1.370 (2) | C5'—C6' | 1.394 (3) |
O4—C8 | 1.425 (3) | C5'—H5' | 0.9300 |
O5—C4' | 1.366 (2) | C6'—H6' | 0.9300 |
O5—C9 | 1.410 (3) | C3—C4 | 1.369 (3) |
C4'—C5' | 1.376 (3) | C3—H3A | 0.9300 |
C4'—C3' | 1.407 (3) | C4—H4 | 0.9300 |
C1—C6 | 1.391 (3) | C8—H8A | 0.9600 |
C1—C2 | 1.403 (3) | C8—H8B | 0.9600 |
C2—C3 | 1.397 (3) | C8—H8C | 0.9600 |
C2—C7 | 1.480 (3) | C9—H9A | 0.9600 |
C3'—C2' | 1.384 (3) | C9—H9B | 0.9600 |
C6—C5 | 1.375 (3) | C9—H9C | 0.9600 |
C6—H6 | 0.96 (2) | | |
| | | |
C3'—O4—C8 | 118.16 (17) | O2—C7—O3 | 121.77 (18) |
C7—O3—H3 | 109.5 | O2—C7—C2 | 121.20 (17) |
C1—O1—C1' | 118.16 (15) | O3—C7—C2 | 117.04 (19) |
C4'—O5—C9 | 117.90 (17) | C4'—C5'—C6' | 121.0 (2) |
O5—C4'—C5' | 125.47 (19) | C4'—C5'—H5' | 119.5 |
O5—C4'—C3' | 114.88 (16) | C6'—C5'—H5' | 119.5 |
C5'—C4'—C3' | 119.65 (18) | C1'—C6'—C5' | 118.81 (18) |
O1—C1—C6 | 121.75 (17) | C1'—C6'—H6' | 120.6 |
O1—C1—C2 | 117.97 (16) | C5'—C6'—H6' | 120.6 |
C6—C1—C2 | 120.27 (19) | C4—C3—C2 | 121.93 (19) |
C3—C2—C1 | 117.91 (17) | C4—C3—H3A | 119.0 |
C3—C2—C7 | 117.95 (17) | C2—C3—H3A | 119.0 |
C1—C2—C7 | 124.14 (18) | C3—C4—C5 | 119.1 (2) |
O4—C3'—C2' | 125.06 (19) | C3—C4—H4 | 120.5 |
O4—C3'—C4' | 115.35 (16) | C5—C4—H4 | 120.5 |
C2'—C3'—C4' | 119.59 (18) | O4—C8—H8A | 109.5 |
C5—C6—C1 | 119.70 (19) | O4—C8—H8B | 109.5 |
C5—C6—H6 | 120.7 (13) | H8A—C8—H8B | 109.5 |
C1—C6—H6 | 119.6 (13) | O4—C8—H8C | 109.5 |
C3'—C2'—C1' | 119.4 (2) | H8A—C8—H8C | 109.5 |
C3'—C2'—H2' | 120.3 | H8B—C8—H8C | 109.5 |
C1'—C2'—H2' | 120.3 | O5—C9—H9A | 109.5 |
C6'—C1'—C2' | 121.58 (18) | O5—C9—H9B | 109.5 |
C6'—C1'—O1 | 119.29 (19) | H9A—C9—H9B | 109.5 |
C2'—C1'—O1 | 119.0 (2) | O5—C9—H9C | 109.5 |
C6—C5—C4 | 121.1 (2) | H9A—C9—H9C | 109.5 |
C6—C5—H5 | 119.8 (15) | H9B—C9—H9C | 109.5 |
C4—C5—H5 | 119.0 (15) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O2i | 0.82 | 1.81 | 2.612 (3) | 168 |
O3—H3···O3i | 0.82 | 2.78 | 3.449 (4) | 140 |
Symmetry code: (i) −x+1, −y, −z+1. |
(III) 1,2-Dimethoxy-9
H-xanthen-9-one
top
Crystal data top
C15H12O4 | Dx = 1.407 Mg m−3 |
Mr = 256.25 | Melting point = 406–408 K |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71069 Å |
a = 4.953 (2) Å | Cell parameters from 1542 reflections |
b = 13.930 (6) Å | θ = 3.7–24.1° |
c = 17.670 (8) Å | µ = 0.10 mm−1 |
β = 97.23 (6)° | T = 293 K |
V = 1209.5 (9) Å3 | Rectangular prism, yellow |
Z = 4 | 0.60 × 0.25 × 0.20 mm |
F(000) = 536 | |
Data collection top
Stoe IPDS diffractometer | 1225 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.056 |
Graphite monochromator | θmax = 24.1°, θmin = 3.7° |
Image Plate scans | h = −5→5 |
7542 measured reflections | k = −15→15 |
1807 independent reflections | l = −20→20 |
Refinement top
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)] = 0.052 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.168 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.08P)2 + 0.422P] where P = (Fo2 + 2Fc2)/3 |
1807 reflections | (Δ/σ)max = 0.001 |
180 parameters | Δρmax = 0.17 e Å−3 |
0 restraints | Δρmin = −0.16 e Å−3 |
Crystal data top
C15H12O4 | V = 1209.5 (9) Å3 |
Mr = 256.25 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 4.953 (2) Å | µ = 0.10 mm−1 |
b = 13.930 (6) Å | T = 293 K |
c = 17.670 (8) Å | 0.60 × 0.25 × 0.20 mm |
β = 97.23 (6)° | |
Data collection top
Stoe IPDS diffractometer | 1225 reflections with I > 2σ(I) |
7542 measured reflections | Rint = 0.056 |
1807 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.052 | 0 restraints |
wR(F2) = 0.168 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.17 e Å−3 |
1807 reflections | Δρmin = −0.16 e Å−3 |
180 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 | x | y | z | Uiso*/Ueq | |
O10 | 0.1782 (4) | 0.04584 (12) | 0.12661 (11) | 0.0671 (6) | |
O11 | 0.6932 (4) | 0.25908 (13) | 0.31078 (12) | 0.0722 (6) | |
O12 | 0.9964 (5) | 0.11133 (14) | 0.36272 (12) | 0.0788 (7) | |
O13 | 0.2837 (5) | 0.32503 (13) | 0.20306 (12) | 0.0824 (7) | |
C1 | 0.6361 (6) | 0.17037 (18) | 0.27668 (16) | 0.0614 (7) | |
C2 | 0.8009 (6) | 0.0927 (2) | 0.30233 (16) | 0.0634 (7) | |
C3 | 0.7572 (6) | 0.00285 (19) | 0.26745 (17) | 0.0661 (8) | |
H3 | 0.8704 | −0.0484 | 0.2836 | 0.079* | |
C4 | 0.5477 (6) | −0.0101 (2) | 0.20938 (16) | 0.0644 (8) | |
H4 | 0.502 (6) | −0.076 (2) | 0.1884 (16) | 0.074 (8)* | |
C5 | −0.2023 (7) | 0.0912 (2) | 0.04099 (17) | 0.0735 (8) | |
H5 | −0.2205 | 0.0277 | 0.0249 | 0.088* | |
C6 | −0.3784 (7) | 0.1603 (3) | 0.00908 (18) | 0.0820 (9) | |
H6 | −0.5162 | 0.1432 | −0.0293 | 0.098* | |
C7 | −0.3548 (7) | 0.2560 (2) | 0.03311 (19) | 0.0795 (9) | |
H7 | −0.4756 | 0.3021 | 0.0109 | 0.095* | |
C8 | −0.1530 (7) | 0.2813 (2) | 0.08945 (18) | 0.0739 (9) | |
H8 | −0.131 (6) | 0.347 (2) | 0.1089 (17) | 0.081 (9)* | |
C9 | 0.2513 (6) | 0.23974 (19) | 0.18346 (16) | 0.0643 (8) | |
C11 | 0.5135 (7) | 0.2855 (2) | 0.36529 (19) | 0.0802 (9) | |
H11A | 0.5650 | 0.3473 | 0.3864 | 0.120* | |
H11B | 0.5259 | 0.2387 | 0.4054 | 0.120* | |
H11C | 0.3299 | 0.2882 | 0.3404 | 0.120* | |
C12 | 1.1668 (8) | 0.0336 (2) | 0.3915 (2) | 0.0874 (10) | |
H12A | 1.2944 | 0.0557 | 0.4333 | 0.131* | |
H12B | 1.2637 | 0.0094 | 0.3518 | 0.131* | |
H12C | 1.0569 | −0.0166 | 0.4088 | 0.131* | |
C4a | 0.3821 (6) | 0.06718 (18) | 0.18490 (15) | 0.0595 (7) | |
C8a | 0.0339 (6) | 0.21248 (19) | 0.12325 (15) | 0.0616 (7) | |
C9a | 0.4242 (6) | 0.15965 (17) | 0.21638 (15) | 0.0590 (7) | |
C10a | 0.0032 (6) | 0.1177 (2) | 0.09776 (15) | 0.0637 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O10 | 0.0663 (14) | 0.0570 (11) | 0.0760 (12) | 0.0006 (9) | 0.0010 (10) | −0.0071 (9) |
O11 | 0.0668 (15) | 0.0565 (11) | 0.0931 (14) | −0.0060 (9) | 0.0087 (10) | −0.0137 (10) |
O12 | 0.0740 (15) | 0.0685 (12) | 0.0886 (14) | 0.0055 (10) | −0.0094 (11) | −0.0082 (10) |
O13 | 0.0887 (18) | 0.0516 (12) | 0.1030 (16) | 0.0015 (10) | −0.0036 (12) | −0.0062 (10) |
C1 | 0.0600 (19) | 0.0510 (15) | 0.0737 (17) | −0.0050 (12) | 0.0099 (13) | −0.0052 (12) |
C2 | 0.0582 (19) | 0.0609 (16) | 0.0698 (16) | −0.0010 (12) | 0.0028 (13) | −0.0038 (12) |
C3 | 0.068 (2) | 0.0551 (16) | 0.0750 (17) | 0.0035 (12) | 0.0107 (14) | 0.0009 (13) |
C4 | 0.068 (2) | 0.0502 (15) | 0.0755 (18) | −0.0007 (13) | 0.0092 (14) | −0.0043 (12) |
C5 | 0.068 (2) | 0.0779 (19) | 0.0739 (19) | −0.0058 (15) | 0.0058 (15) | −0.0072 (15) |
C6 | 0.073 (2) | 0.095 (2) | 0.0761 (19) | 0.0000 (18) | 0.0013 (16) | 0.0039 (17) |
C7 | 0.072 (2) | 0.082 (2) | 0.084 (2) | 0.0077 (16) | 0.0042 (17) | 0.0097 (17) |
C8 | 0.073 (2) | 0.0691 (19) | 0.080 (2) | 0.0038 (15) | 0.0115 (16) | 0.0060 (15) |
C9 | 0.064 (2) | 0.0543 (16) | 0.0757 (17) | 0.0002 (13) | 0.0128 (14) | 0.0000 (13) |
C11 | 0.081 (2) | 0.0732 (19) | 0.086 (2) | 0.0033 (16) | 0.0103 (17) | −0.0193 (16) |
C12 | 0.082 (3) | 0.081 (2) | 0.094 (2) | 0.0100 (17) | −0.0081 (18) | 0.0014 (17) |
C4a | 0.0576 (19) | 0.0537 (15) | 0.0671 (16) | −0.0026 (12) | 0.0067 (13) | −0.0025 (12) |
C8a | 0.0592 (19) | 0.0591 (16) | 0.0668 (16) | −0.0001 (12) | 0.0087 (13) | 0.0021 (12) |
C9a | 0.0580 (19) | 0.0480 (14) | 0.0714 (16) | −0.0024 (11) | 0.0100 (13) | −0.0029 (11) |
C10a | 0.062 (2) | 0.0618 (16) | 0.0681 (16) | 0.0017 (13) | 0.0112 (13) | 0.0001 (13) |
Geometric parameters (Å, º) top
O10—C10a | 1.379 (3) | C5—C6 | 1.372 (5) |
O10—C4a | 1.381 (3) | C5—H5 | 0.9300 |
O11—C1 | 1.388 (3) | C11—H11A | 0.9600 |
O11—C11 | 1.439 (4) | C11—H11B | 0.9600 |
O12—C2 | 1.373 (3) | C11—H11C | 0.9600 |
O12—C12 | 1.426 (4) | C8—C7 | 1.365 (5) |
O13—C9 | 1.242 (3) | C8—H8 | 0.98 (3) |
C2—C1 | 1.396 (4) | C7—C6 | 1.400 (5) |
C2—C3 | 1.400 (4) | C7—H7 | 0.9300 |
C9a—C1 | 1.406 (4) | C3—C4 | 1.376 (4) |
C9a—C4a | 1.408 (4) | C3—H3 | 0.9300 |
C9a—C9 | 1.480 (4) | C4—H4 | 1.00 (3) |
C8a—C10a | 1.397 (4) | C6—H6 | 0.9300 |
C8a—C8 | 1.412 (4) | C12—H12A | 0.9600 |
C8a—C9 | 1.465 (4) | C12—H12B | 0.9600 |
C4a—C4 | 1.389 (4) | C12—H12C | 0.9600 |
C10a—C5 | 1.387 (4) | | |
| | | |
C10a—O10—C4a | 119.1 (2) | O11—C11—H11C | 109.5 |
C1—O11—C11 | 114.1 (2) | H11A—C11—H11C | 109.5 |
C2—O12—C12 | 117.5 (2) | H11B—C11—H11C | 109.5 |
O12—C2—C1 | 115.6 (2) | C7—C8—C8a | 121.0 (3) |
O12—C2—C3 | 124.5 (3) | C7—C8—H8 | 122.3 (18) |
C1—C2—C3 | 119.9 (3) | C8a—C8—H8 | 116.7 (18) |
C1—C9a—C4a | 117.1 (2) | C8—C7—C6 | 119.5 (3) |
C1—C9a—C9 | 123.9 (2) | C8—C7—H7 | 120.3 |
C4a—C9a—C9 | 119.0 (2) | C6—C7—H7 | 120.3 |
C10a—C8a—C8 | 117.8 (3) | C4—C3—C2 | 120.4 (3) |
C10a—C8a—C9 | 121.3 (3) | C4—C3—H3 | 119.8 |
C8—C8a—C9 | 120.9 (3) | C2—C3—H3 | 119.8 |
O10—C4a—C4 | 114.4 (2) | C3—C4—C4a | 119.4 (3) |
O10—C4a—C9a | 123.3 (2) | C3—C4—H4 | 120.7 (17) |
C4—C4a—C9a | 122.3 (3) | C4a—C4—H4 | 119.7 (17) |
O10—C10a—C5 | 116.3 (3) | O13—C9—C8a | 120.5 (3) |
O10—C10a—C8a | 121.9 (3) | O13—C9—C9a | 124.3 (3) |
C5—C10a—C8a | 121.7 (3) | C8a—C9—C9a | 115.2 (2) |
O11—C1—C2 | 118.0 (3) | C5—C6—C7 | 121.3 (3) |
O11—C1—C9a | 121.0 (2) | C5—C6—H6 | 119.4 |
C2—C1—C9a | 120.9 (2) | C7—C6—H6 | 119.4 |
C6—C5—C10a | 118.8 (3) | O12—C12—H12A | 109.5 |
C6—C5—H5 | 120.6 | O12—C12—H12B | 109.5 |
C10a—C5—H5 | 120.6 | H12A—C12—H12B | 109.5 |
O11—C11—H11A | 109.5 | O12—C12—H12C | 109.5 |
O11—C11—H11B | 109.5 | H12A—C12—H12C | 109.5 |
H11A—C11—H11B | 109.5 | H12B—C12—H12C | 109.5 |
(IV) 1,2,8-Trimethoxy-9
H-xanthen-9-one
top
Crystal data top
C16H14O5 | Dx = 1.411 Mg m−3 |
Mr = 286.27 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 1345 reflections |
a = 5.273 (1) Å | θ = 4.1–24.2° |
b = 15.443 (4) Å | µ = 0.11 mm−1 |
c = 16.550 (6) Å | T = 293 K |
V = 1347.7 (7) Å3 | Rectangular prism, colourless |
Z = 4 | 0.8 × 0.5 × 0.3 mm |
F(000) = 600 | |
Data collection top
Stoe IPDS diffractometer | 1887 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.039 |
Graphite monochromator | θmax = 24.2°, θmin = 4.1° |
Image Plate scans | h = −5→5 |
8453 measured reflections | k = −17→17 |
2068 independent reflections | l = −18→18 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.042 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.108 | w = 1/[σ2(Fo2) + (0.046P)2 + 0.426P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.001 |
2068 reflections | Δρmax = 0.14 e Å−3 |
210 parameters | Δρmin = −0.11 e Å−3 |
0 restraints | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: not reliably determined |
Crystal data top
C16H14O5 | V = 1347.7 (7) Å3 |
Mr = 286.27 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 5.273 (1) Å | µ = 0.11 mm−1 |
b = 15.443 (4) Å | T = 293 K |
c = 16.550 (6) Å | 0.8 × 0.5 × 0.3 mm |
Data collection top
Stoe IPDS diffractometer | 1887 reflections with I > 2σ(I) |
8453 measured reflections | Rint = 0.039 |
2068 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.042 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.108 | Δρmax = 0.14 e Å−3 |
S = 1.03 | Δρmin = −0.11 e Å−3 |
2068 reflections | Absolute structure: Flack (1983) |
210 parameters | Absolute structure parameter: not reliably determined |
0 restraints | |
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 | x | y | z | Uiso*/Ueq | |
O10 | 0.1263 (4) | 0.98200 (11) | 0.76476 (10) | 0.0659 (5) | |
O11 | −0.1765 (4) | 1.02405 (12) | 0.49169 (9) | 0.0650 (5) | |
O12 | −0.4768 (4) | 0.88684 (14) | 0.50771 (12) | 0.0889 (7) | |
O13 | 0.4716 (4) | 1.23093 (12) | 0.63195 (11) | 0.0751 (6) | |
O14 | 0.0708 (4) | 1.15012 (12) | 0.57548 (11) | 0.0767 (6) | |
C1 | −0.1870 (5) | 0.98420 (16) | 0.56569 (14) | 0.0578 (6) | |
C2 | −0.3372 (5) | 0.91028 (18) | 0.57463 (16) | 0.0656 (7) | |
C3 | −0.3319 (6) | 0.8639 (2) | 0.64644 (18) | 0.0732 (8) | |
H3 | −0.450 (7) | 0.811 (2) | 0.651 (2) | 0.100 (11)* | |
C4 | −0.1762 (7) | 0.88916 (18) | 0.70914 (19) | 0.0707 (7) | |
H4 | −0.170 (7) | 0.857 (2) | 0.7581 (18) | 0.086 (9)* | |
C5 | 0.4639 (6) | 1.05602 (18) | 0.82292 (16) | 0.0665 (7) | |
H5 | 0.455 (6) | 1.015 (2) | 0.8658 (18) | 0.083 (9)* | |
C6 | 0.6424 (6) | 1.12058 (19) | 0.82110 (18) | 0.0703 (8) | |
H6 | 0.767 (6) | 1.1247 (18) | 0.8633 (18) | 0.079 (9)* | |
C7 | 0.6530 (6) | 1.17989 (19) | 0.75761 (16) | 0.0665 (7) | |
H7 | 0.773 (6) | 1.2248 (18) | 0.7577 (16) | 0.070 (8)* | |
C8 | 0.4804 (6) | 1.17423 (15) | 0.69478 (14) | 0.0591 (6) | |
C9 | 0.1117 (5) | 1.09513 (16) | 0.62757 (14) | 0.0573 (6) | |
C11 | −0.3865 (6) | 1.0794 (2) | 0.47141 (19) | 0.0817 (9) | |
H11A | −0.3601 | 1.1037 | 0.4187 | 0.123* | |
H11B | −0.3991 | 1.1251 | 0.5105 | 0.123* | |
H11C | −0.5404 | 1.0462 | 0.4715 | 0.123* | |
C12 | −0.6838 (6) | 0.8298 (2) | 0.5180 (2) | 0.0866 (9) | |
H12A | −0.7649 | 0.8203 | 0.4669 | 0.130* | |
H12B | −0.8032 | 0.8548 | 0.5551 | 0.130* | |
H12C | −0.6240 | 0.7756 | 0.5391 | 0.130* | |
C13 | 0.6603 (7) | 1.29780 (18) | 0.62707 (19) | 0.0792 (8) | |
H13A | 0.6317 | 1.3321 | 0.5795 | 0.119* | |
H13B | 0.8257 | 1.2720 | 0.6243 | 0.119* | |
H13C | 0.6497 | 1.3340 | 0.6741 | 0.119* | |
C4a | −0.0259 (5) | 0.96225 (15) | 0.69987 (14) | 0.0581 (6) | |
C8a | 0.2966 (5) | 1.10672 (15) | 0.69314 (14) | 0.0536 (6) | |
C9a | −0.0338 (5) | 1.01263 (15) | 0.62985 (13) | 0.0536 (6) | |
C10a | 0.2972 (6) | 1.04926 (16) | 0.75881 (14) | 0.0586 (6) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O10 | 0.0733 (12) | 0.0665 (10) | 0.0580 (9) | −0.0065 (9) | −0.0047 (9) | 0.0109 (8) |
O11 | 0.0660 (11) | 0.0795 (11) | 0.0495 (9) | 0.0052 (10) | 0.0019 (9) | 0.0011 (8) |
O12 | 0.0872 (15) | 0.1058 (15) | 0.0738 (13) | −0.0327 (13) | −0.0056 (12) | −0.0122 (11) |
O13 | 0.0863 (14) | 0.0677 (11) | 0.0712 (11) | −0.0177 (11) | −0.0085 (11) | 0.0100 (9) |
O14 | 0.0875 (14) | 0.0716 (11) | 0.0710 (11) | −0.0105 (10) | −0.0148 (11) | 0.0216 (9) |
C1 | 0.0582 (14) | 0.0638 (14) | 0.0515 (13) | 0.0020 (13) | 0.0025 (11) | −0.0015 (11) |
C2 | 0.0640 (16) | 0.0696 (16) | 0.0632 (15) | −0.0068 (14) | 0.0046 (14) | −0.0106 (12) |
C3 | 0.076 (2) | 0.0709 (18) | 0.0730 (18) | −0.0128 (16) | 0.0078 (16) | 0.0005 (14) |
C4 | 0.0772 (19) | 0.0676 (16) | 0.0672 (16) | −0.0063 (16) | 0.0039 (16) | 0.0091 (13) |
C5 | 0.0768 (19) | 0.0679 (15) | 0.0548 (14) | 0.0044 (15) | −0.0082 (14) | 0.0050 (13) |
C6 | 0.073 (2) | 0.0738 (17) | 0.0641 (16) | 0.0087 (15) | −0.0126 (15) | −0.0097 (14) |
C7 | 0.0680 (18) | 0.0666 (16) | 0.0648 (16) | −0.0032 (14) | −0.0056 (14) | −0.0091 (13) |
C8 | 0.0685 (16) | 0.0548 (13) | 0.0542 (13) | −0.0002 (13) | 0.0021 (12) | −0.0013 (11) |
C9 | 0.0615 (15) | 0.0580 (13) | 0.0523 (13) | 0.0056 (11) | 0.0031 (12) | 0.0048 (11) |
C11 | 0.075 (2) | 0.094 (2) | 0.0765 (18) | 0.0180 (17) | −0.0089 (16) | 0.0082 (16) |
C12 | 0.0642 (19) | 0.087 (2) | 0.109 (2) | −0.0118 (17) | −0.0058 (18) | −0.0153 (19) |
C13 | 0.084 (2) | 0.0636 (16) | 0.090 (2) | −0.0209 (15) | 0.0031 (19) | 0.0065 (14) |
C4a | 0.0590 (15) | 0.0597 (13) | 0.0554 (14) | 0.0006 (12) | 0.0013 (12) | 0.0004 (11) |
C8a | 0.0602 (15) | 0.0504 (12) | 0.0502 (12) | 0.0031 (11) | 0.0004 (11) | 0.0015 (9) |
C9a | 0.0553 (14) | 0.0553 (12) | 0.0503 (12) | 0.0015 (11) | 0.0039 (11) | 0.0018 (10) |
C10a | 0.0662 (17) | 0.0576 (13) | 0.0521 (13) | 0.0037 (12) | 0.0023 (12) | 0.0001 (10) |
Geometric parameters (Å, º) top
O10—C4a | 1.375 (3) | C7—H7 | 0.94 (3) |
O10—C10a | 1.379 (3) | C9a—C1 | 1.404 (3) |
O11—C1 | 1.372 (3) | C9a—C9 | 1.488 (3) |
O11—C11 | 1.438 (3) | C4—C3 | 1.379 (4) |
O12—C2 | 1.378 (3) | C4—H4 | 0.95 (3) |
O12—C12 | 1.413 (4) | C13—H13A | 0.9600 |
O13—C8 | 1.360 (3) | C13—H13B | 0.9600 |
O13—C13 | 1.436 (3) | C13—H13C | 0.9600 |
O14—C9 | 1.229 (3) | C12—H12A | 0.9600 |
C8a—C10a | 1.403 (3) | C12—H12B | 0.9600 |
C8a—C8 | 1.424 (4) | C12—H12C | 0.9600 |
C8a—C9 | 1.470 (3) | C1—C2 | 1.398 (4) |
C5—C6 | 1.371 (4) | C2—C3 | 1.387 (4) |
C5—C10a | 1.382 (4) | C6—H6 | 0.96 (3) |
C5—H5 | 0.95 (3) | C3—H3 | 1.03 (4) |
C8—C7 | 1.385 (4) | C11—H11A | 0.9600 |
C4a—C4 | 1.388 (4) | C11—H11B | 0.9600 |
C4a—C9a | 1.396 (3) | C11—H11C | 0.9600 |
C7—C6 | 1.395 (4) | | |
| | | |
C4a—O10—C10a | 119.53 (19) | O13—C13—H13A | 109.5 |
C1—O11—C11 | 116.4 (2) | O13—C13—H13B | 109.5 |
C8—O13—C13 | 118.8 (2) | H13A—C13—H13B | 109.5 |
C10a—C8a—C8 | 116.5 (2) | O13—C13—H13C | 109.5 |
C10a—C8a—C9 | 119.8 (2) | H13A—C13—H13C | 109.5 |
C8—C8a—C9 | 123.7 (2) | H13B—C13—H13C | 109.5 |
C6—C5—C10a | 118.3 (3) | O12—C12—H12A | 109.5 |
C6—C5—H5 | 122.3 (19) | O12—C12—H12B | 109.5 |
C10a—C5—H5 | 119.3 (19) | H12A—C12—H12B | 109.5 |
O13—C8—C7 | 123.8 (2) | O12—C12—H12C | 109.5 |
O13—C8—C8a | 115.7 (2) | H12A—C12—H12C | 109.5 |
C7—C8—C8a | 120.5 (2) | H12B—C12—H12C | 109.5 |
O10—C10a—C5 | 114.7 (2) | O11—C1—C2 | 118.9 (2) |
O10—C10a—C8a | 122.0 (2) | O11—C1—C9a | 120.8 (2) |
C5—C10a—C8a | 123.3 (3) | C2—C1—C9a | 120.1 (2) |
O10—C4a—C4 | 115.3 (2) | O12—C2—C3 | 124.3 (3) |
O10—C4a—C9a | 122.8 (2) | O12—C2—C1 | 115.6 (2) |
C4—C4a—C9a | 121.9 (2) | C3—C2—C1 | 120.0 (3) |
C8—C7—C6 | 119.9 (3) | C5—C6—C7 | 121.4 (3) |
C8—C7—H7 | 119.4 (17) | C5—C6—H6 | 120.0 (18) |
C6—C7—H7 | 120.7 (17) | C7—C6—H6 | 118.5 (18) |
C4a—C9a—C1 | 118.1 (2) | C4—C3—C2 | 120.7 (3) |
C4a—C9a—C9 | 118.9 (2) | C4—C3—H3 | 121.5 (19) |
C1—C9a—C9 | 123.0 (2) | C2—C3—H3 | 117.8 (19) |
C2—O12—C12 | 118.6 (2) | O11—C11—H11A | 109.5 |
O14—C9—C8a | 123.4 (2) | O11—C11—H11B | 109.5 |
O14—C9—C9a | 121.3 (2) | H11A—C11—H11B | 109.5 |
C8a—C9—C9a | 115.3 (2) | O11—C11—H11C | 109.5 |
C3—C4—C4a | 119.1 (3) | H11A—C11—H11C | 109.5 |
C3—C4—H4 | 121 (2) | H11B—C11—H11C | 109.5 |
C4a—C4—H4 | 120 (2) | | |
Experimental details
| (I) | (II) | (III) | (IV) |
Crystal data |
Chemical formula | C16H16O5 | C15H14O5 | C15H12O4 | C16H14O5 |
Mr | 288.29 | 274.26 | 256.25 | 286.27 |
Crystal system, space group | Monoclinic, P21/c | Triclinic, P1 | Monoclinic, P21/n | Orthorhombic, P212121 |
Temperature (K) | 293 | 293 | 293 | 293 |
a, b, c (Å) | 15.306 (7), 7.788 (4), 16.426 (7) | 7.920 (4), 8.550 (5), 11.360 (7) | 4.953 (2), 13.930 (6), 17.670 (8) | 5.273 (1), 15.443 (4), 16.550 (6) |
α, β, γ (°) | 90, 132.31 (3), 90 | 76.02 (7), 82.46 (7), 64.20 (6) | 90, 97.23 (6), 90 | 90, 90, 90 |
V (Å3) | 1448.0 (12) | 671.8 (7) | 1209.5 (9) | 1347.7 (7) |
Z | 4 | 2 | 4 | 4 |
Radiation type | Mo Kα | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 0.10 | 0.10 | 0.10 | 0.11 |
Crystal size (mm) | 0.30 × 0.25 × 0.20 | 0.7 × 0.4 × 0.3 | 0.60 × 0.25 × 0.20 | 0.8 × 0.5 × 0.3 |
|
Data collection |
Diffractometer | Stoe IPDS diffractometer | Stoe IPDS diffractometer | Stoe IPDS diffractometer | Stoe IPDS diffractometer |
Absorption correction | – | – | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13194, 3439, 2221 | 4584, 1923, 1618 | 7542, 1807, 1225 | 8453, 2068, 1887 |
Rint | 0.068 | 0.047 | 0.056 | 0.039 |
(sin θ/λ)max (Å−1) | 0.663 | 0.575 | 0.575 | 0.576 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.165, 1.05 | 0.050, 0.159, 1.06 | 0.052, 0.168, 1.07 | 0.042, 0.108, 1.03 |
No. of reflections | 3439 | 1923 | 1807 | 2068 |
No. of parameters | 254 | 189 | 180 | 210 |
H-atom treatment | All H-atom parameters refined | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.23, −0.22 | 0.14, −0.15 | 0.17, −0.16 | 0.14, −0.11 |
Absolute structure | ? | ? | ? | Flack (1983) |
Absolute structure parameter | ? | ? | ? | not reliably determined |
Selected bond lengths (Å) for (I) topO1—C1 | 1.370 (3) | C2'—C3' | 1.389 (3) |
O1—C1' | 1.405 (2) | C3'—C4' | 1.410 (3) |
O4—C3' | 1.371 (2) | C4'—C5' | 1.383 (3) |
O4—C8 | 1.429 (3) | C5'—C6' | 1.397 (3) |
O5—C4' | 1.369 (2) | C1—C6 | 1.391 (3) |
O5—C9 | 1.422 (3) | C1—C2 | 1.411 (3) |
O2—C7 | 1.200 (2) | C2—C3 | 1.394 (3) |
O3—C7 | 1.310 (3) | C2—C7 | 1.493 (3) |
O3—C10 | 1.444 (3) | C3—C4 | 1.380 (3) |
C1'—C6' | 1.368 (3) | C4—C5 | 1.387 (3) |
C1'—C2' | 1.393 (3) | C5—C6 | 1.377 (3) |
Selected bond lengths (Å) for (II) topO1—C1 | 1.376 (2) | C1—C2 | 1.403 (3) |
O1—C1' | 1.403 (2) | C2—C3 | 1.397 (3) |
O2—C7 | 1.257 (3) | C2—C7 | 1.480 (3) |
O3—C7 | 1.268 (2) | C3'—C2' | 1.384 (3) |
O4—C3' | 1.370 (2) | C6—C5 | 1.375 (3) |
O4—C8 | 1.425 (3) | C2'—C1' | 1.393 (3) |
O5—C4' | 1.366 (2) | C1'—C6' | 1.369 (3) |
O5—C9 | 1.410 (3) | C5—C4 | 1.382 (3) |
C4'—C5' | 1.376 (3) | C5'—C6' | 1.394 (3) |
C4'—C3' | 1.407 (3) | C3—C4 | 1.369 (3) |
C1—C6 | 1.391 (3) | | |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O2i | 0.82 | 1.81 | 2.612 (3) | 168 |
O3—H3···O3i | 0.82 | 2.78 | 3.449 (4) | 140 |
Symmetry code: (i) −x+1, −y, −z+1. |
Selected bond lengths (Å) for (III) topO10—C10a | 1.379 (3) | C9a—C9 | 1.480 (4) |
O10—C4a | 1.381 (3) | C8a—C10a | 1.397 (4) |
O11—C1 | 1.388 (3) | C8a—C8 | 1.412 (4) |
O11—C11 | 1.439 (4) | C8a—C9 | 1.465 (4) |
O12—C2 | 1.373 (3) | C4a—C4 | 1.389 (4) |
O12—C12 | 1.426 (4) | C10a—C5 | 1.387 (4) |
O13—C9 | 1.242 (3) | C5—C6 | 1.372 (5) |
C2—C1 | 1.396 (4) | C8—C7 | 1.365 (5) |
C2—C3 | 1.400 (4) | C7—C6 | 1.400 (5) |
C9a—C1 | 1.406 (4) | C3—C4 | 1.376 (4) |
C9a—C4a | 1.408 (4) | | |
Selected bond lengths (Å) for (IV) topO10—C4a | 1.375 (3) | C5—C6 | 1.371 (4) |
O10—C10a | 1.379 (3) | C5—C10a | 1.382 (4) |
O11—C1 | 1.372 (3) | C8—C7 | 1.385 (4) |
O11—C11 | 1.438 (3) | C4a—C4 | 1.388 (4) |
O12—C2 | 1.378 (3) | C4a—C9a | 1.396 (3) |
O12—C12 | 1.413 (4) | C7—C6 | 1.395 (4) |
O13—C8 | 1.360 (3) | C9a—C1 | 1.404 (3) |
O13—C13 | 1.436 (3) | C9a—C9 | 1.488 (3) |
O14—C9 | 1.229 (3) | C4—C3 | 1.379 (4) |
C8a—C10a | 1.403 (3) | C1—C2 | 1.398 (4) |
C8a—C8 | 1.424 (4) | C2—C3 | 1.387 (4) |
C8a—C9 | 1.470 (3) | | |
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Xanthones are major secondary metabolites of the plants of the family Guttiferae (Bennett & Lee, 1989). Both synthetic and naturally occurring xanthones have been reported to mediate various biological effects, such as hepatoprotection (Fernandes et al., 1995) and reversible monoamine oxidase A inhibitors (Thull et al., 1993; Fujimoto et al., 1998). As part of our ongoing research concerning the variety of biological properties of this class of compounds, we have investigated the xanthone constituents of Calophyllum teysmanii var. inophylloide and studied their immunomodulatory activity (Gonzalez et al., 1999).
Among the xanthones tested, 2-hydroxy-1-methoxyxanthone has been shown to exhibit the highest inhibitory activity on T-cell proliferation. Further examination of the extract of Calophyllum teysmanii var. inophylloide has led to an isolation of, among many known xanthones, the new xanthones 1,2,8-trimethoxy-9H-xanthen-9-one, (IV), and 1,3,5,7-tetramethoxyxanthone (Kijjoa et al., 2000). However, the biological activities of these xanthones have not yet been evaluated. Taking into account the variety of biological properties of xanthones, we have planned the synthesis of a series of 1,2-dioxygenated xanthones to evaluate their antitumour and immunomodulatory activities. The syntheses of some 1,2-dioxygenated xanthones have been reported previously: 1,2-dimethoxy-9H-xanthen-9-one, (III), was obtained in a very low yield by a multi-step synthesis of its intermediate 1-formyl-2-hydroxyxanthone (Golberg & Wragg, 1958). More recently, 1-hydroxy-2-methoxyxanthone has been prepared by an LDA-induced regiospecific route from diaryl ether 2-carbohexamines (Familoni et al., 1997). Please define LDA. In contrast, we have succeeded in preparing (III) by a facile one-step conversion of the diaryl intermediate 2-(3,4-dimethoxyphenoxy)benzoic acid, (II), into the corresponding xanthone. In this paper, we report the structures of the intermediate compounds, methyl 2-(3,4-dimethoxyphenoxy)benzoate, (I), and 2-(3,4-dimethoxyphenoxy)benzoic acid, (II), obtained during the synthesis of (III), as well as the structure of this xanthone compared with (IV), which is very similar and was isolated from a plant. \sch
Compounds (I) and (II) (Figs. 1 and 2) differ only in the substituent at C2, which is a methyl ester in (I) and a carboxylic acid group in (II). They both assume a skew conformation, the angle between the phenyl rings being 80.04 (8)° for (I) and 83.0 (1)° for (II). These angles are in close agreement with the value of 84.8 (1)° observed in another open-ring intermediate for the synthesis of xanthones (Damas et al., 1997).
In (I), the plane defined by C1, O1 and C1' makes an angle of 4.8 (1)° with the C1—C6 phenyl ring plane and 76.5 (2)° with the other ring, C1'-C6'. The methyl ester group is nearly coplanar with the phenyl ring, as shown by the r.m.s. deviations from the ring plane: C7 0.039 (3), O2 0.173 (4), O3 - 0.079 (4) and C10 - 0.029 (6) Å. Furthermore, the bond angles between the methyl ester group and the phenyl ring C atoms adjacent to C2 are 126.3 (2)° for C1—C2—C7 and 115.8 (2)° for C3—C2—C7. The difference between these angles (10.4°) is probably due to a requirement of minimum steric interaction of the methyl ester group with the other phenyl ring.
The two methoxy substituents do not diverge significantly from the ring plane, as shown by the torsion angles C3'-C4'-O5—C9 [177.8 (2)°] and C4'-C3'-O4—C8 [176.9 (2)°]. Again, the orientation of the two methoxy substituents appears to have been determined by the requirement of minimum steric interaction between them.
In (II), the C1—C6 phenyl ring is nearly coplanar with the C1/O1/C1' plane, the relevant angle being 1.4 (2)°. The angle between the other ring, C1'-C6', and the C1/O1/C1' plane is 84.3 (2)°. The carboxylic acid group is nearly coplanar with the phenyl ring, the r.m.s. deviations from the ring plane being 0.036 (3), 0.132 (4) and -0.034 (4) Å for C7, O2 and O3, respectively. The C1—C2—C7 angle of 124.1 (2)° is 6.2° wider than the C3—C2—C7 angle [117.9 (2)°]; this difference is smaller than observed for (I), probably because the substituent in (I) is larger. The two methoxy substituents are in the plane of the phenyl ring [C3'-C4'-O5—C9 179.2 (2)° and C4'-C3'-O4—C8 179.8 (2)°], as in (I). Compound (II) also shows two intermolecular hydrogen bonds: O3···O2i 2.612 (3) and O3···O3i 3.449 (4) Å [symmetry code: (i) 1 - x, -y, 3 - z]. Further details of these are given in Table 3.
The 1,2-dimethoxy-9H-xanthen-9-one molecule in (III) is nearly planar (Fig. 3); the three rings define a plane with an r.m.s. deviation for the fitted atoms of 0.0297 Å. The maximum deviation of the O atoms, which were not included in the calculation of the least squares plane, is 0.14 Å for O13. Of the two methoxy substituents on the phenyl ring, one methyl group lies much further out of the ring plane than does the other [C2—C1—O11—C11 - 102.5 (3), compared with C1—C2—O12—C12 179.1 (3)°]. Atom C11 is probably forced out of the phenyl plane due to the proximity of atoms O13 and O12. Adoption of these orientations of the phenyl rings with multiple methoxy substituents has been observed previously and is consistent with minimum steric interactions (Hibbs et al., 1995; Kijjoa et al., 1998).
In the 1,2,8-trimethoxy-9H-xanthen-9-one compound, (IV), isolated from the wood of Callophyllum teysmanii var. inophylloide, two of the methyl groups of the three methoxy substituents are much closer to the plane of the molecule than the other (Fig. 4), as shown by the torsion angles C1—C2—O12—C12 [-162.0 (2)°], C2—C1—O11—C11 [79.6 (3)°] and C7—C8—O13—C13 [3.9 (4)°]. As in (III), atom C11 lies out of the ring plane, probably to minimize the steric interactions due to the presence of atoms O12 and O14 on either side of the methoxy group.
Papers describing the biological activity of these four compounds are in preparation. Comparison of the three-dimensional structure of molecules (III) and (IV) with those of the xanthone constituents of Calophyllum teysmanii var. inophylloide, whose activity has been studied, will reveal details of the relationship between structure and activity for this class of compounds.