organic compounds
7,7′-Dihydroxy-4,4′-dimethyl-3,4-dihydro-2H,2′H-4,6′-bichromene-2,2′-dione
aCEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra, Portugal, and bDepartment of Chemistry, Aligarh Muslim University, Aligarh 202002, India
*Correspondence e-mail: psidonio@pollux.fis.uc.pt
The title compound, C20H16O6, which contains one chiral centre, crystallizes as a racemate. The mean planes of the two coumarin units make a dihedral angle of 88.07 (2)°. The pyrone ring containing the chiral centre adopts a sofa conformation. In the crystal, four molecules are linked by O—H⋯O hydrogen bonds, forming a tetrameric ring with graph-set motif R44(32). These tetramers are further linked by O—H⋯O hydrogen bonds into a three-dimensional network.
Related literature
For the chemical reactivity and bioactivity of et al. (2004). For a review on bicoumarins, see: Basa (1988). For the synthesis of bicoumarins, see: Ilyas & Parveen (1996); Sharma et al. (1977); Gašparová et al. (2009). For the synthesis of the title compound, see: Parveen et al. (1991). For hydrogen-bond motifs, see: Etter et al. (1990).
and derivatives, see: FylaktakidouExperimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2003); cell SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97.
Supporting information
https://doi.org/10.1107/S160053681005244X/bt5436sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681005244X/bt5436Isup2.hkl
Polyphospharic acid was prepared by mixing orthophosphoric acid (15 mL) and phosphorus pentaoxide (23.5 g) followed by heating on a water bath for 1.5 hr. A catalytic amount of polyphosphoric acid (160 g) was added to resorcinol (11 g, 100 mmol) and ethyl acetoacetate (13 mL, 100 mmol) and was heated on a water bath (75–80 °C) for 20 min. with stirring. The viscous mixture was then poured into ice cold water and the resulting solid (18 g, m.p. 180 °C) was crystallized with EtOH as shinning crystal (7 g), it was characterized as 7-hydroxy-4-methyl coumarin by comparison with authentic sample. The mother liquor showed the presence of two bands I&II (TLC, silica-gel, benzene-ethylacetate 2:1) which was separated into individual compounds by preparative thin layer
in the same solvent. The compound I was identified as 7-hydroxy-4-methyl coumarin while the compound II (m.p. 305 °C) was characterized as a novel coumarin dimer, (I), by IR, 1H NMR, 13C NMR & MS spectra.All H atoms were located in a difference Fourier synthesis, placed in calculated positions and refined as riding on their parent atoms, using SHELXL97 (Sheldrick, 2008) defaults.
Studies of natural and synthetic
and its derivatives have been present for a number of years. and their derivatives are characterized by excellent chemical reactivity and bioactivity (Fylaktakidou et al., 2004). Bicoumarins are a comparatively new class of naturally occurring compounds (Basa, 1988) and are reputed for their biological activities such as anticoagulant, anticancer, antifungal agents. Only few bicoumarins have been synthesized (Ilyas & Parveen, 1996; Sharma & Seshadri, 1977; Gašparová et al., 2009). Considering the biological importance and scarcity of work on coumarin dimer a novel coumarin dimer 7,7'-dihydroxy-4,4'-dimethyl-3,4-dihydro-2H,2'H-4,6'- bichromene-2,2'-dione (I) was synthesized by the reinvestigation of synthesis of 7-hydroxy-4-methyl coumarin with the condensation of resorcinol and ethyl acetoacetate in different molar ratio using catalytic amount of polyphospharic acid (PPA) (Parveen et al., 1991). The increase in molar ratio of ethyl acetoacetate leads to a slight increase of coumarin dimer (I).The title compound, (I), Fig. 1, has one chiral carbon atom (the C11 atom). Both enantiomers are present in the
forming a racemate.In the molecule of (I), the mean planes of the two coumarin units make a dihedral angle of 88.07 (2). In one of the coumarin units, the the dihedral angle between the least-squares planes of the pyrone and benzene rings is 3.36 (6)°. In the other coumarin unit the pyrone ring adopts an
and the dihedral angle with the aromatic ring is 13.23 (6)°.In the crystal, the molecules are linked by O—H···O hydrogen bonds (Fig. 2, Table 2) forming rings with four molecules, graph-set motif R44(32), according to the Etter's graph-set theory (Etter et al., 1990), centered about inversion centres. These rings are linked, with each molecule participating in two rings, forming a three-dimensional network. The structure is stabilized further by weak C—H···O hydrogen bonds.
For literature on the chemical reactivity and bioactivity of
and derivatives see: Fylaktakidou et al., (2004) For a review on bicoumarins see: Basa, (1988) For the synthesis of bicoumarins see: Ilyas & Parveen, (1996); Sharma et al., (1977); Gašparová et al., (2009). For the synthesis of the title compound, see: Parveen et al. (1991). For hydrogen bond motifs, see: Etter et al. (1990).Data collection: SMART (Bruker, 2003); cell
SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. A plot of the title compound. Displacement ellipsoids are drawn at the 50% probability level. | |
Fig. 2. One of the R44(32) rings. The hydrogen bonds are depicted by dashed lines. |
C20H16O6 | F(000) = 736 |
Mr = 352.33 | Dx = 1.397 Mg m−3 |
Monoclinic, P21/c | Melting point: 578 K |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 9.0432 (2) Å | Cell parameters from 6612 reflections |
b = 11.5111 (2) Å | θ = 2.5–26.9° |
c = 17.2212 (4) Å | µ = 0.10 mm−1 |
β = 110.870 (1)° | T = 293 K |
V = 1675.06 (6) Å3 | Block, colourless |
Z = 4 | 0.39 × 0.29 × 0.22 mm |
Bruker APEXII CCD area-detector diffractometer | 4457 independent reflections |
Radiation source: fine-focus sealed tube | 3459 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
φ and ω scans | θmax = 29.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | h = −12→12 |
Tmin = 0.863, Tmax = 0.977 | k = −15→15 |
44743 measured reflections | l = −23→23 |
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)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.109 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0494P)2 + 0.3328P] where P = (Fo2 + 2Fc2)/3 |
4457 reflections | (Δ/σ)max = 0.001 |
239 parameters | Δρmax = 0.24 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C20H16O6 | V = 1675.06 (6) Å3 |
Mr = 352.33 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.0432 (2) Å | µ = 0.10 mm−1 |
b = 11.5111 (2) Å | T = 293 K |
c = 17.2212 (4) Å | 0.39 × 0.29 × 0.22 mm |
β = 110.870 (1)° |
Bruker APEXII CCD area-detector diffractometer | 4457 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 3459 reflections with I > 2σ(I) |
Tmin = 0.863, Tmax = 0.977 | Rint = 0.032 |
44743 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.109 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.24 e Å−3 |
4457 reflections | Δρmin = −0.19 e Å−3 |
239 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.74647 (10) | 0.54064 (8) | 0.87909 (5) | 0.0368 (2) | |
O2 | 0.54717 (11) | 0.46437 (9) | 0.90479 (6) | 0.0493 (3) | |
O3 | 1.15727 (12) | 0.69823 (9) | 0.80504 (6) | 0.0451 (2) | |
H3 | 1.1142 | 0.6550 | 0.7656 | 0.068* | |
O4 | 1.12946 (11) | 1.04007 (8) | 0.96142 (5) | 0.0417 (2) | |
O5 | 1.02955 (13) | 1.03756 (9) | 0.82593 (6) | 0.0524 (3) | |
O6 | 1.36961 (17) | 1.09547 (11) | 1.24734 (7) | 0.0741 (4) | |
H6 | 1.4319 | 1.0663 | 1.2899 | 0.111* | |
C15 | 1.32138 (13) | 0.89438 (10) | 1.03809 (7) | 0.0316 (2) | |
C1 | 0.67075 (14) | 0.51800 (11) | 0.93326 (8) | 0.0354 (3) | |
C2 | 0.74199 (14) | 0.55917 (10) | 1.01676 (8) | 0.0342 (3) | |
H2 | 0.6960 | 0.5393 | 1.0554 | 0.041* | |
C3 | 0.87346 (13) | 0.62569 (10) | 1.04157 (7) | 0.0299 (2) | |
C4 | 0.94702 (13) | 0.65387 (9) | 0.98182 (7) | 0.0269 (2) | |
C5 | 0.88131 (13) | 0.60745 (10) | 0.90244 (7) | 0.0291 (2) | |
C6 | 0.94786 (14) | 0.62367 (11) | 0.84276 (7) | 0.0341 (3) | |
H6A | 0.9014 | 0.5908 | 0.7903 | 0.041* | |
C7 | 1.08379 (14) | 0.68894 (10) | 0.86131 (7) | 0.0319 (2) | |
C8 | 1.14982 (13) | 0.74657 (9) | 0.93879 (7) | 0.0286 (2) | |
C9 | 1.07994 (13) | 0.72530 (9) | 0.99702 (7) | 0.0281 (2) | |
H9 | 1.1234 | 0.7602 | 1.0489 | 0.034* | |
C10 | 0.94310 (18) | 0.66923 (12) | 1.12910 (8) | 0.0429 (3) | |
H10A | 0.8821 | 0.6405 | 1.1606 | 0.064* | |
H10B | 0.9415 | 0.7526 | 1.1291 | 0.064* | |
H10C | 1.0503 | 0.6425 | 1.1537 | 0.064* | |
C11 | 1.29393 (13) | 0.82800 (10) | 0.95799 (7) | 0.0318 (2) | |
C12 | 1.26202 (16) | 0.92183 (11) | 0.88992 (8) | 0.0386 (3) | |
H12A | 1.3578 | 0.9666 | 0.8997 | 0.046* | |
H12B | 1.2353 | 0.8842 | 0.8363 | 0.046* | |
C13 | 1.13148 (16) | 1.00189 (10) | 0.88775 (8) | 0.0378 (3) | |
C14 | 1.24095 (14) | 0.99771 (10) | 1.03566 (7) | 0.0338 (3) | |
C16 | 1.42053 (15) | 0.85861 (11) | 1.11672 (8) | 0.0393 (3) | |
H16 | 1.4763 | 0.7894 | 1.1218 | 0.047* | |
C17 | 1.43867 (16) | 0.92269 (12) | 1.18742 (8) | 0.0456 (3) | |
H17 | 1.5052 | 0.8961 | 1.2390 | 0.055* | |
C18 | 1.35767 (17) | 1.02674 (13) | 1.18141 (8) | 0.0460 (3) | |
C19 | 1.25766 (17) | 1.06437 (12) | 1.10452 (8) | 0.0428 (3) | |
H19 | 1.2024 | 1.1338 | 1.0994 | 0.051* | |
C20 | 1.44116 (15) | 0.75869 (12) | 0.96108 (9) | 0.0440 (3) | |
H20A | 1.4596 | 0.6973 | 1.0012 | 0.066* | |
H20B | 1.5313 | 0.8094 | 0.9767 | 0.066* | |
H20C | 1.4245 | 0.7261 | 0.9073 | 0.066* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0348 (4) | 0.0447 (5) | 0.0291 (4) | −0.0113 (4) | 0.0090 (4) | −0.0025 (4) |
O2 | 0.0374 (5) | 0.0640 (6) | 0.0427 (5) | −0.0179 (4) | 0.0095 (4) | 0.0013 (5) |
O3 | 0.0555 (6) | 0.0535 (6) | 0.0338 (5) | −0.0153 (5) | 0.0250 (4) | −0.0071 (4) |
O4 | 0.0494 (5) | 0.0416 (5) | 0.0294 (4) | 0.0115 (4) | 0.0082 (4) | 0.0055 (4) |
O5 | 0.0673 (7) | 0.0513 (6) | 0.0321 (5) | 0.0083 (5) | 0.0099 (5) | 0.0129 (4) |
O6 | 0.0944 (10) | 0.0718 (8) | 0.0366 (6) | 0.0264 (7) | −0.0004 (6) | −0.0133 (5) |
C15 | 0.0309 (6) | 0.0287 (5) | 0.0329 (6) | −0.0062 (4) | 0.0087 (5) | 0.0019 (4) |
C1 | 0.0316 (6) | 0.0374 (6) | 0.0360 (6) | −0.0017 (5) | 0.0105 (5) | 0.0052 (5) |
C2 | 0.0345 (6) | 0.0376 (6) | 0.0341 (6) | 0.0009 (5) | 0.0165 (5) | 0.0032 (5) |
C3 | 0.0351 (6) | 0.0268 (5) | 0.0295 (5) | 0.0035 (4) | 0.0134 (5) | 0.0015 (4) |
C4 | 0.0292 (5) | 0.0251 (5) | 0.0255 (5) | 0.0020 (4) | 0.0087 (4) | 0.0015 (4) |
C5 | 0.0288 (5) | 0.0285 (5) | 0.0278 (5) | −0.0021 (4) | 0.0073 (4) | 0.0010 (4) |
C6 | 0.0407 (6) | 0.0372 (6) | 0.0226 (5) | −0.0054 (5) | 0.0091 (5) | −0.0026 (4) |
C7 | 0.0388 (6) | 0.0327 (6) | 0.0268 (5) | −0.0007 (5) | 0.0147 (5) | 0.0023 (4) |
C8 | 0.0312 (5) | 0.0247 (5) | 0.0290 (5) | −0.0001 (4) | 0.0099 (5) | 0.0021 (4) |
C9 | 0.0329 (6) | 0.0254 (5) | 0.0246 (5) | 0.0005 (4) | 0.0085 (4) | 0.0002 (4) |
C10 | 0.0587 (8) | 0.0417 (7) | 0.0325 (6) | −0.0083 (6) | 0.0215 (6) | −0.0054 (5) |
C11 | 0.0327 (6) | 0.0290 (5) | 0.0336 (6) | −0.0028 (4) | 0.0116 (5) | 0.0023 (4) |
C12 | 0.0486 (7) | 0.0342 (6) | 0.0373 (6) | −0.0056 (5) | 0.0208 (6) | 0.0042 (5) |
C13 | 0.0509 (7) | 0.0309 (6) | 0.0314 (6) | −0.0048 (5) | 0.0143 (6) | 0.0069 (5) |
C14 | 0.0343 (6) | 0.0330 (6) | 0.0298 (6) | −0.0015 (5) | 0.0063 (5) | 0.0050 (5) |
C16 | 0.0359 (6) | 0.0341 (6) | 0.0402 (7) | 0.0004 (5) | 0.0040 (5) | 0.0033 (5) |
C17 | 0.0428 (7) | 0.0480 (7) | 0.0334 (6) | 0.0006 (6) | −0.0017 (6) | 0.0035 (6) |
C18 | 0.0499 (8) | 0.0469 (7) | 0.0339 (7) | 0.0001 (6) | 0.0061 (6) | −0.0047 (6) |
C19 | 0.0492 (8) | 0.0371 (6) | 0.0379 (7) | 0.0059 (6) | 0.0104 (6) | 0.0001 (5) |
C20 | 0.0363 (7) | 0.0437 (7) | 0.0543 (8) | 0.0002 (5) | 0.0190 (6) | −0.0004 (6) |
O1—C1 | 1.3646 (14) | C7—C8 | 1.4176 (16) |
O1—C5 | 1.3751 (13) | C8—C9 | 1.3844 (15) |
O2—C1 | 1.2166 (15) | C8—C11 | 1.5424 (15) |
O3—C7 | 1.3604 (13) | C9—H9 | 0.9300 |
O3—H3 | 0.8200 | C10—H10A | 0.9600 |
O4—C13 | 1.3489 (15) | C10—H10B | 0.9600 |
O4—C14 | 1.4036 (14) | C10—H10C | 0.9600 |
O5—C13 | 1.2052 (15) | C11—C20 | 1.5367 (17) |
O6—C18 | 1.3561 (17) | C11—C12 | 1.5437 (16) |
O6—H6 | 0.8200 | C12—C13 | 1.4876 (19) |
C15—C14 | 1.3871 (17) | C12—H12A | 0.9700 |
C15—C16 | 1.3936 (17) | C12—H12B | 0.9700 |
C15—C11 | 1.5180 (16) | C14—C19 | 1.3749 (18) |
C1—C2 | 1.4308 (17) | C16—C17 | 1.3824 (19) |
C2—C3 | 1.3492 (16) | C16—H16 | 0.9300 |
C2—H2 | 0.9300 | C17—C18 | 1.388 (2) |
C3—C4 | 1.4472 (15) | C17—H17 | 0.9300 |
C3—C10 | 1.4978 (16) | C18—C19 | 1.3805 (19) |
C4—C5 | 1.3887 (15) | C19—H19 | 0.9300 |
C4—C9 | 1.4019 (15) | C20—H20A | 0.9600 |
C5—C6 | 1.3763 (16) | C20—H20B | 0.9600 |
C6—C7 | 1.3776 (16) | C20—H20C | 0.9600 |
C6—H6A | 0.9300 | ||
C1—O1—C5 | 121.03 (9) | H10A—C10—H10C | 109.5 |
C7—O3—H3 | 109.5 | H10B—C10—H10C | 109.5 |
C13—O4—C14 | 119.83 (10) | C15—C11—C20 | 111.76 (10) |
C18—O6—H6 | 109.5 | C15—C11—C8 | 110.66 (9) |
C14—C15—C16 | 115.58 (11) | C20—C11—C8 | 110.33 (10) |
C14—C15—C11 | 119.34 (10) | C15—C11—C12 | 105.29 (9) |
C16—C15—C11 | 125.07 (11) | C20—C11—C12 | 108.35 (10) |
O2—C1—O1 | 115.72 (11) | C8—C11—C12 | 110.32 (10) |
O2—C1—C2 | 126.38 (11) | C13—C12—C11 | 112.62 (10) |
O1—C1—C2 | 117.90 (10) | C13—C12—H12A | 109.1 |
C3—C2—C1 | 122.46 (11) | C11—C12—H12A | 109.1 |
C3—C2—H2 | 118.8 | C13—C12—H12B | 109.1 |
C1—C2—H2 | 118.8 | C11—C12—H12B | 109.1 |
C2—C3—C4 | 118.58 (10) | H12A—C12—H12B | 107.8 |
C2—C3—C10 | 121.05 (11) | O5—C13—O4 | 117.23 (12) |
C4—C3—C10 | 120.37 (10) | O5—C13—C12 | 125.71 (12) |
C5—C4—C9 | 116.57 (10) | O4—C13—C12 | 117.05 (11) |
C5—C4—C3 | 118.02 (10) | C19—C14—C15 | 123.86 (11) |
C9—C4—C3 | 125.41 (10) | C19—C14—O4 | 114.47 (11) |
O1—C5—C6 | 115.82 (10) | C15—C14—O4 | 121.62 (11) |
O1—C5—C4 | 121.80 (10) | C17—C16—C15 | 122.11 (12) |
C6—C5—C4 | 122.37 (10) | C17—C16—H16 | 118.9 |
C5—C6—C7 | 119.49 (10) | C15—C16—H16 | 118.9 |
C5—C6—H6A | 120.3 | C16—C17—C18 | 120.06 (12) |
C7—C6—H6A | 120.3 | C16—C17—H17 | 120.0 |
O3—C7—C6 | 119.98 (10) | C18—C17—H17 | 120.0 |
O3—C7—C8 | 119.00 (10) | O6—C18—C19 | 116.71 (13) |
C6—C7—C8 | 121.03 (10) | O6—C18—C17 | 123.94 (13) |
C9—C8—C7 | 116.82 (10) | C19—C18—C17 | 119.34 (13) |
C9—C8—C11 | 121.40 (10) | C14—C19—C18 | 119.04 (12) |
C7—C8—C11 | 121.78 (10) | C14—C19—H19 | 120.5 |
C8—C9—C4 | 123.42 (10) | C18—C19—H19 | 120.5 |
C8—C9—H9 | 118.3 | C11—C20—H20A | 109.5 |
C4—C9—H9 | 118.3 | C11—C20—H20B | 109.5 |
C3—C10—H10A | 109.5 | H20A—C20—H20B | 109.5 |
C3—C10—H10B | 109.5 | C11—C20—H20C | 109.5 |
H10A—C10—H10B | 109.5 | H20A—C20—H20C | 109.5 |
C3—C10—H10C | 109.5 | H20B—C20—H20C | 109.5 |
C5—O1—C1—O2 | 175.48 (11) | C16—C15—C11—C8 | 92.09 (14) |
C5—O1—C1—C2 | −4.23 (16) | C14—C15—C11—C12 | 32.87 (14) |
O2—C1—C2—C3 | −174.86 (13) | C16—C15—C11—C12 | −148.70 (12) |
O1—C1—C2—C3 | 4.81 (18) | C9—C8—C11—C15 | −10.98 (14) |
C1—C2—C3—C4 | −1.56 (17) | C7—C8—C11—C15 | 169.78 (10) |
C1—C2—C3—C10 | 178.78 (12) | C9—C8—C11—C20 | 113.22 (12) |
C2—C3—C4—C5 | −2.19 (16) | C7—C8—C11—C20 | −66.02 (14) |
C10—C3—C4—C5 | 177.46 (11) | C9—C8—C11—C12 | −127.09 (11) |
C2—C3—C4—C9 | 177.44 (11) | C7—C8—C11—C12 | 53.67 (14) |
C10—C3—C4—C9 | −2.90 (17) | C15—C11—C12—C13 | −54.35 (13) |
C1—O1—C5—C6 | 179.56 (11) | C20—C11—C12—C13 | −174.05 (11) |
C1—O1—C5—C4 | 0.53 (16) | C8—C11—C12—C13 | 65.08 (13) |
C9—C4—C5—O1 | −176.89 (10) | C14—O4—C13—O5 | 177.23 (11) |
C3—C4—C5—O1 | 2.77 (16) | C14—O4—C13—C12 | −4.36 (16) |
C9—C4—C5—C6 | 4.14 (16) | C11—C12—C13—O5 | −138.57 (13) |
C3—C4—C5—C6 | −176.19 (11) | C11—C12—C13—O4 | 43.17 (15) |
O1—C5—C6—C7 | −179.59 (10) | C16—C15—C14—C19 | 1.57 (18) |
C4—C5—C6—C7 | −0.57 (18) | C11—C15—C14—C19 | −179.86 (12) |
C5—C6—C7—O3 | 175.00 (11) | C16—C15—C14—O4 | −175.78 (11) |
C5—C6—C7—C8 | −4.60 (18) | C11—C15—C14—O4 | 2.79 (17) |
O3—C7—C8—C9 | −173.82 (10) | C13—O4—C14—C19 | 162.46 (12) |
C6—C7—C8—C9 | 5.79 (16) | C13—O4—C14—C15 | −19.96 (17) |
O3—C7—C8—C11 | 5.46 (17) | C14—C15—C16—C17 | −0.69 (18) |
C6—C7—C8—C11 | −174.94 (10) | C11—C15—C16—C17 | −179.17 (12) |
C7—C8—C9—C4 | −2.04 (16) | C15—C16—C17—C18 | −0.5 (2) |
C11—C8—C9—C4 | 178.69 (10) | C16—C17—C18—O6 | −179.39 (15) |
C5—C4—C9—C8 | −2.76 (16) | C16—C17—C18—C19 | 0.9 (2) |
C3—C4—C9—C8 | 177.60 (10) | C15—C14—C19—C18 | −1.2 (2) |
C14—C15—C11—C20 | 150.29 (11) | O4—C14—C19—C18 | 176.31 (12) |
C16—C15—C11—C20 | −31.29 (16) | O6—C18—C19—C14 | −179.82 (14) |
C14—C15—C11—C8 | −86.33 (12) | C17—C18—C19—C14 | −0.1 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O5i | 0.82 | 2.13 | 2.9406 (13) | 169 |
O6—H6···O2ii | 0.82 | 1.91 | 2.7024 (15) | 161 |
Symmetry codes: (i) −x+2, y−1/2, −z+3/2; (ii) x+1, −y+3/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C20H16O6 |
Mr | 352.33 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 9.0432 (2), 11.5111 (2), 17.2212 (4) |
β (°) | 110.870 (1) |
V (Å3) | 1675.06 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.39 × 0.29 × 0.22 |
Data collection | |
Diffractometer | Bruker APEXII CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) |
Tmin, Tmax | 0.863, 0.977 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 44743, 4457, 3459 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.682 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.109, 1.06 |
No. of reflections | 4457 |
No. of parameters | 239 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.19 |
Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O5i | 0.82 | 2.13 | 2.9406 (13) | 169.3 |
O6—H6···O2ii | 0.82 | 1.91 | 2.7024 (15) | 161.3 |
Symmetry codes: (i) −x+2, y−1/2, −z+3/2; (ii) x+1, −y+3/2, z+1/2. |
Acknowledgements
This work was supported by the Fundação para a Ciência e a Tecnologia (FCT) under the scholarship SFRH/BD/38387/2008.
References
Basa, S. B. (1988). Phytochemistry, 27, 1933–1941. CrossRef CAS Google Scholar
Bruker (2003). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262. CrossRef CAS Web of Science IUCr Journals Google Scholar
Fylaktakidou, K. C., Hadjipavlou-Litina, D. J., Litinas, K. E. & Nicolaides, D. N. (2004). Curr. Pharm. Des. 10, 3813–3833. Web of Science CrossRef PubMed CAS Google Scholar
Gašparová, R., Kotlebová, K. & Lácová, M. (2009). Nova Biotechnol. 9, 349–354. Google Scholar
Ilyas, M. & Parveen, M. (1996). Tetrahedron, 52, 3991–3996. CrossRef CAS Web of Science Google Scholar
Parveen, M., Khan, N. U.-D. & Logani, M. K. (1991). J. Indian Chem. Soc. 68, 617–618. CAS Google Scholar
Sharma, D. K. & Seshadri, T. R. (1977). Indian J. Chem. 15, 939–341. Google Scholar
Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Studies of natural and synthetic coumarins and its derivatives have been present for a number of years. Coumarins and their derivatives are characterized by excellent chemical reactivity and bioactivity (Fylaktakidou et al., 2004). Bicoumarins are a comparatively new class of naturally occurring compounds (Basa, 1988) and are reputed for their biological activities such as anticoagulant, anticancer, antifungal agents. Only few bicoumarins have been synthesized (Ilyas & Parveen, 1996; Sharma & Seshadri, 1977; Gašparová et al., 2009). Considering the biological importance and scarcity of work on coumarin dimer a novel coumarin dimer 7,7'-dihydroxy-4,4'-dimethyl-3,4-dihydro-2H,2'H-4,6'- bichromene-2,2'-dione (I) was synthesized by the reinvestigation of synthesis of 7-hydroxy-4-methyl coumarin with the condensation of resorcinol and ethyl acetoacetate in different molar ratio using catalytic amount of polyphospharic acid (PPA) (Parveen et al., 1991). The increase in molar ratio of ethyl acetoacetate leads to a slight increase of coumarin dimer (I).
The title compound, (I), Fig. 1, has one chiral carbon atom (the C11 atom). Both enantiomers are present in the crystal structure, forming a racemate.
In the molecule of (I), the mean planes of the two coumarin units make a dihedral angle of 88.07 (2). In one of the coumarin units, the the dihedral angle between the least-squares planes of the pyrone and benzene rings is 3.36 (6)°. In the other coumarin unit the pyrone ring adopts an envelope conformation and the dihedral angle with the aromatic ring is 13.23 (6)°.
In the crystal, the molecules are linked by O—H···O hydrogen bonds (Fig. 2, Table 2) forming rings with four molecules, graph-set motif R44(32), according to the Etter's graph-set theory (Etter et al., 1990), centered about inversion centres. These rings are linked, with each molecule participating in two rings, forming a three-dimensional network. The structure is stabilized further by weak C—H···O hydrogen bonds.