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Acta Cryst. (2009). E65, o314-o315    [ doi:10.1107/S1600536809001019 ]

Dimethyl 2,2'-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: a less densely packed polymorph

A. Nallasivam, M. Nethaji, N. Vembu, B. Jaswant and N. Sulochana

Abstract top

The title molecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o312-o313]. The main difference between the two polymorphs is in the conformation of the oxomethylacetate groups with regard to the almost planar [total puckering amplitude 0.047 (2) Å] chromene ring. In the title compound, the best planes of the oxomethylacetate groups through the non-H atoms are almost perpendicular to the chromene ring [making dihedral angles of 89.61 (6) and 80.59 (5)°], while in the second polymorph the molecules are close to planar. Both crystal structures are stabilized by C-H...O.

Comment top

Chromenes (benzopyrans) and their derivatives have numerous biological and pharmacological properties (Tang et al., 2007) such as antisterility (Brooks, 1998) and anticancer activity (Hyana & Saimoto, 1987). In addition, polyfunctional chromene units are present in numerous natural products (Hatakeyama et al., 1988). 4H-chromenes are important synthons for some natural products (Liu et al., 2007). As a part of our structural investigations on 4H-chromene derivatives and compounds containing the benzopyran fragment, the single-crystal X-ray diffraction study on the title compound was carried out.

The chromene ring is almost planar. This planarity is common for the related chromene derivatives (Wei et al., 2003; Wang et al., 2003). The total puckering amplitude of the chromene ring in the title structure is 0.047 (2) Å. The interplanar angle between the chromene ring and the 2-phenyl ring is 17.20 (7)° thereby indicating the distorted coplanar arrangement (Fig. 1). This angle is substantially larger than in the other polymorph (Nallasivam et al., 2009) that is only 2.90 (6)°. In the title structure, both oxomethylacetate groups are almost perpendicular to the plane of the chromene ring; the planes through their non-hydrogen atoms contain the angles with the plane through the non-hydrogen chromene-ring atoms equal to 89.61 (6) and 80.59 (5)° for the groups attached at C5 and C7, respectively. This is the main difference to the second polymorph (Nallasivam et al., 2009) where the respective angles are 6.60 (64), 22 (4) and 12.45 (5)° for the chains A and B attached to C5 and to the chain attached to C7.

It should be noted that the title compound is considerably less densely packed than the second polymorph (the respective unit cell volumes are 941.3 (3) (the title structure) and 915.5 (3) Å3 (Nallasivam et al., 2009). The reason plausibly consists in the different shapes of the molecules in both polymorphs; a more planar shape of the second polymorph enables a denser packing of the molecules in spite of a partial disorder of the oxomethylacetate group attached to C5.

The weak interactions are of a similar character in both polymorphs: C—H···O, C—H···π electron and π-π electron interactions. However, the number of weak interactions in the title structure is lower than in the second polymorph (Nallasivam et al., 2009).

The weak C–H···O and C–H···π interactions are given in Tab. 1; Desiraju & Steiner, 1999). The C19—H19A···O17i and C19—H19A···O18i interactions constitute a pair of bifurcated donor bonds generating a ring of graph set R21(6) (Bernstein et al., 1995; Etter, 1990). There is also a face to face interaction between two symmetry related (1-x, -y, 1-z) (O1\C2\C3\C4\C9\C10) rings with mutual distance between the centroids being 3.633 (1) Å.

Related literature top

For a more densely packed molecule, see: Nallasivam et al. (2009). For the biological and pharmacological properties of benzopyrans and their derivatives, see: Brooks (1998); Hatakeyama et al. (1988); Hyana & Saimoto (1987); Tang et al. (2007). For the importance of 4H-chromenes, see Liu et al. (2007); Wang, Fang et al. (2003); Wand, Zheng et al. (2003). Cg3 is the centroid of the C11–C16 ring. For hydrogen-bond motifs, see: Bernstein et al. (1995); Desiraju & Steiner (1999); Etter (1990).

Experimental top

The title compound was prepared from the more densely packed polymorph (Nallasivam et al., 2009). The crude product of the above polymorph (1.26 mmol, 0.5 g) was dissolved in dichloromethane (10 ml). The content was cooled to 283–288 K and AlCl3 (1.50 mmol, 0.2 g) was added. Acetyl chloride (21.21 mmol, 1.5 ml) was added dropwise over a period of 15–20 min. The reaction mixture was maintained for 10–12 hrs at 283–288 K, quenched with HCl/ice mixture, extracted with dichloromethane and purified by column chromatography, using 20 ml of 1:1 (volume) mixture of ethyl acetate and n-hexane. Diffraction quality prism shaped crystals of the title compound, the less densely packed polymorph, with average size about 0.35 mm along its long edge were obtained. Yield: 80%

Refinement top

All the H-atoms were observed in the difference electron density map. However, they were situated into idealized positions with C–H = 0.93, 0.97 and 0.96Å for aryl, methylene and methyl H, respectively, and constrained to ride on their parent atoms with Uiso(H)=1.2Ueq(C) for the aryl and methylene H and Uiso(H)=1.5Ueq(C) for the methyl H.

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SMART (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The title molecule showing the displacement ellipsoids depicted at the 50% probability level for all non-H atoms. The hydrogen atoms are drawn as spheres of arbitrary radius.
Dimethyl 2,2'-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate top
Crystal data top
C21H18O8Z = 2
Mr = 398.35F(000) = 416
Triclinic, P1Dx = 1.406 Mg m−3
Hall symbol: -P 1Melting point = 418–420 K
a = 9.4024 (16) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.8506 (17) ÅCell parameters from 576 reflections
c = 11.1570 (18) Åθ = 2.0–27.0°
α = 67.817 (3)°µ = 0.11 mm−1
β = 80.300 (3)°T = 293 K
γ = 89.683 (3)°Prism, colourless
V = 941.3 (3) Å30.42 × 0.35 × 0.29 mm
Data collection top
Bruker SMART APEX CCD
diffractometer		4316 independent reflections
Radiation source: fine-focus sealed tube2424 reflections with I > 2σ(I)
graphiteRint = 0.026
Detector resolution: 0.3 pixels mm-1θmax = 28.0°, θmin = 2.0°
ω scansh = −12→12
Absorption correction: multi-scan
(SADABS; Sheldrick, 1998)		k = −12→12
Tmin = 0.955, Tmax = 0.969l = −14→12
8351 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.055Hydrogen site location: difference Fourier map
wR(F2) = 0.140H-atom parameters constrained
S = 0.98 w = 1/[σ2(Fo2) + (0.0653P)2]
where P = (Fo2 + 2Fc2)/3
4316 reflections(Δ/σ)max < 0.001
264 parametersΔρmax = 0.17 e Å−3
0 restraintsΔρmin = −0.17 e Å−3
72 constraints
Crystal data top
C21H18O8γ = 89.683 (3)°
Mr = 398.35V = 941.3 (3) Å3
Triclinic, P1Z = 2
a = 9.4024 (16) ÅMo Kα radiation
b = 9.8506 (17) ŵ = 0.11 mm−1
c = 11.1570 (18) ÅT = 293 K
α = 67.817 (3)°0.42 × 0.35 × 0.29 mm
β = 80.300 (3)°
Data collection top
Bruker SMART APEX CCD
diffractometer		4316 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1998)		2424 reflections with I > 2σ(I)
Tmin = 0.955, Tmax = 0.969Rint = 0.026
8351 measured reflectionsθmax = 28.0°
Refinement top
R[F2 > 2σ(F2)] = 0.055H-atom parameters constrained
wR(F2) = 0.140Δρmax = 0.17 e Å−3
S = 0.98Δρmin = −0.17 e Å−3
4316 reflectionsAbsolute structure: ?
264 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
O10.40612 (14)0.11111 (15)0.61070 (13)0.0480 (4)
C20.3081 (2)0.0338 (2)0.5793 (2)0.0442 (5)
C30.2882 (2)0.0715 (2)0.4561 (2)0.0527 (6)
H30.22340.01330.43870.063*
C40.3620 (2)0.1982 (3)0.3475 (2)0.0537 (6)
C50.5576 (2)0.4028 (2)0.29261 (19)0.0449 (5)
C60.6546 (2)0.4693 (2)0.3356 (2)0.0492 (5)
H60.71230.55100.27580.059*
C70.6676 (2)0.4163 (2)0.4671 (2)0.0465 (5)
C80.5847 (2)0.2951 (2)0.5581 (2)0.0474 (5)
H80.59420.25820.64620.057*
C90.4678 (2)0.2784 (2)0.38264 (19)0.0426 (5)
C100.4865 (2)0.2302 (2)0.51311 (19)0.0424 (5)
C110.2310 (2)−0.0864 (2)0.6973 (2)0.0438 (5)
C120.2836 (2)−0.1350 (2)0.8139 (2)0.0505 (5)
H120.3721−0.09560.81660.061*
C130.2065 (2)−0.2414 (2)0.9265 (2)0.0571 (6)
H130.2432−0.27331.00420.069*
C140.0759 (3)−0.2999 (3)0.9234 (2)0.0643 (7)
H140.0226−0.36940.99970.077*
C150.0242 (3)−0.2560 (3)0.8081 (3)0.0711 (7)
H15−0.0632−0.29790.80580.085*
C160.1004 (2)−0.1503 (3)0.6951 (2)0.0625 (6)
H160.0643−0.12160.61710.075*
O170.33591 (19)0.2322 (2)0.23630 (16)0.0923 (6)
O180.54047 (15)0.44833 (16)0.16484 (13)0.0563 (4)
C190.6399 (2)0.5593 (2)0.06901 (19)0.0516 (5)
H19A0.64120.5540−0.01620.062*
H19B0.73600.54130.09000.062*
C200.6040 (2)0.7112 (2)0.06058 (19)0.0472 (5)
O210.48863 (17)0.74539 (18)0.09905 (16)0.0719 (5)
O220.71948 (15)0.80238 (16)−0.00131 (15)0.0588 (4)
C230.6961 (3)0.9562 (3)−0.0494 (3)0.0925 (9)
H23A0.65180.9818−0.12590.139*
H23B0.78701.0117−0.07210.139*
H23C0.63370.97810.01760.139*
O240.76487 (16)0.49744 (16)0.49501 (14)0.0630 (4)
C250.8002 (2)0.4478 (2)0.6227 (2)0.0540 (6)
H25A0.71260.41180.68800.065*
H25B0.84380.52920.63540.065*
C260.9035 (2)0.3269 (3)0.6417 (2)0.0522 (6)
O270.94183 (18)0.2686 (2)0.56667 (18)0.0864 (6)
O280.94756 (16)0.29423 (18)0.75606 (15)0.0627 (4)
C291.0535 (3)0.1846 (3)0.7853 (3)0.0833 (8)
H29A1.01410.09410.78690.125*
H29B1.07750.16910.86960.125*
H29C1.13890.21790.71890.125*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0492 (8)0.0528 (9)0.0363 (8)−0.0084 (7)−0.0069 (6)−0.0110 (7)
C20.0403 (11)0.0490 (13)0.0444 (13)0.0008 (9)−0.0075 (9)−0.0192 (11)
C30.0504 (12)0.0624 (15)0.0464 (14)−0.0076 (11)−0.0092 (10)−0.0217 (12)
C40.0526 (12)0.0672 (15)0.0401 (13)−0.0024 (11)−0.0141 (10)−0.0167 (12)
C50.0510 (12)0.0457 (12)0.0345 (12)0.0042 (10)−0.0118 (9)−0.0099 (10)
C60.0558 (12)0.0445 (12)0.0395 (12)−0.0049 (10)−0.0098 (10)−0.0066 (10)
C70.0506 (12)0.0455 (13)0.0419 (13)−0.0025 (10)−0.0141 (10)−0.0126 (10)
C80.0552 (12)0.0493 (13)0.0350 (12)−0.0010 (10)−0.0134 (10)−0.0109 (10)
C90.0438 (11)0.0453 (12)0.0369 (12)0.0033 (9)−0.0097 (9)−0.0128 (10)
C100.0419 (11)0.0437 (12)0.0390 (12)0.0014 (9)−0.0064 (9)−0.0131 (10)
C110.0408 (11)0.0475 (13)0.0435 (13)0.0011 (9)−0.0028 (9)−0.0197 (10)
C120.0480 (12)0.0552 (14)0.0453 (13)−0.0071 (10)−0.0045 (10)−0.0173 (11)
C130.0656 (14)0.0572 (15)0.0430 (13)−0.0072 (12)−0.0034 (11)−0.0154 (11)
C140.0662 (15)0.0590 (16)0.0587 (16)−0.0149 (12)0.0072 (12)−0.0201 (13)
C150.0577 (14)0.0760 (18)0.0725 (19)−0.0235 (13)−0.0037 (13)−0.0235 (15)
C160.0535 (13)0.0744 (17)0.0553 (15)−0.0121 (12)−0.0116 (11)−0.0192 (13)
O170.1010 (13)0.1168 (16)0.0438 (10)−0.0444 (11)−0.0271 (9)−0.0072 (10)
O180.0704 (10)0.0583 (10)0.0319 (8)−0.0116 (8)−0.0143 (7)−0.0058 (7)
C190.0572 (13)0.0548 (14)0.0345 (12)−0.0026 (11)−0.0052 (10)−0.0091 (10)
C200.0446 (12)0.0586 (14)0.0347 (12)0.0011 (11)−0.0120 (9)−0.0118 (10)
O210.0556 (10)0.0754 (12)0.0693 (12)0.0106 (9)−0.0034 (8)−0.0140 (9)
O220.0544 (9)0.0552 (10)0.0648 (10)−0.0084 (8)−0.0096 (8)−0.0209 (8)
C230.102 (2)0.0577 (18)0.114 (3)−0.0123 (15)−0.0184 (18)−0.0293 (17)
O240.0775 (10)0.0589 (10)0.0459 (9)−0.0207 (8)−0.0219 (8)−0.0078 (8)
C250.0633 (13)0.0581 (14)0.0429 (13)−0.0102 (11)−0.0143 (10)−0.0195 (11)
C260.0450 (12)0.0653 (15)0.0486 (14)−0.0105 (11)−0.0063 (10)−0.0250 (12)
O270.0782 (12)0.1268 (16)0.0877 (14)0.0158 (11)−0.0217 (10)−0.0756 (13)
O280.0654 (10)0.0762 (11)0.0526 (10)0.0131 (8)−0.0187 (8)−0.0282 (9)
C290.0669 (16)0.091 (2)0.100 (2)0.0190 (15)−0.0314 (15)−0.0389 (18)
Geometric parameters (Å, °) top
O1—C21.368 (2)C14—H140.9300
O1—C101.379 (2)C15—C161.378 (3)
C2—C31.327 (3)C15—H150.9300
C2—C111.474 (3)C16—H160.9300
C3—C41.446 (3)O18—C191.416 (2)
C3—H30.9300C19—C201.503 (3)
C4—O171.225 (2)C19—H19A0.9700
C4—C91.463 (3)C19—H19B0.9700
C5—O181.361 (2)C20—O211.193 (2)
C5—C61.372 (3)C20—O221.324 (2)
C5—C91.421 (3)O22—C231.433 (3)
C6—C71.386 (3)C23—H23A0.9600
C6—H60.9300C23—H23B0.9600
C7—O241.365 (2)C23—H23C0.9600
C7—C81.376 (3)O24—C251.417 (2)
C8—C101.384 (3)C25—C261.507 (3)
C8—H80.9300C25—H25A0.9700
C9—C101.392 (3)C25—H25B0.9700
C11—C121.382 (3)C26—O271.192 (2)
C11—C161.391 (3)C26—O281.330 (2)
C12—C131.382 (3)O28—C291.448 (3)
C12—H120.9300C29—H29A0.9600
C13—C141.370 (3)C29—H29B0.9600
C13—H130.9300C29—H29C0.9600
C14—C151.366 (3)
C2—O1—C10119.73 (16)C14—C15—C16120.6 (2)
C3—C2—O1121.22 (18)C14—C15—H15119.7
C3—C2—C11127.40 (19)C16—C15—H15119.7
O1—C2—C11111.35 (17)C15—C16—C11120.3 (2)
C2—C3—C4123.5 (2)C15—C16—H16119.9
C2—C3—H3118.3C11—C16—H16119.9
C4—C3—H3118.3C5—O18—C19117.84 (16)
O17—C4—C3121.2 (2)O18—C19—C20112.95 (17)
O17—C4—C9124.2 (2)O18—C19—H19A109.0
C3—C4—C9114.51 (18)C20—C19—H19A109.0
O18—C5—C6123.80 (18)O18—C19—H19B109.0
O18—C5—C9115.77 (18)C20—C19—H19B109.0
C6—C5—C9120.43 (18)H19A—C19—H19B107.8
C5—C6—C7120.84 (19)O21—C20—O22125.3 (2)
C5—C6—H6119.6O21—C20—C19125.6 (2)
C7—C6—H6119.6O22—C20—C19109.07 (18)
O24—C7—C8125.08 (18)C20—O22—C23116.67 (18)
O24—C7—C6113.78 (18)O22—C23—H23A109.5
C8—C7—C6121.11 (19)O22—C23—H23B109.5
C7—C8—C10117.24 (19)H23A—C23—H23B109.5
C7—C8—H8121.4O22—C23—H23C109.5
C10—C8—H8121.4H23A—C23—H23C109.5
C10—C9—C5115.94 (18)H23B—C23—H23C109.5
C10—C9—C4118.98 (18)C7—O24—C25119.88 (16)
C5—C9—C4125.06 (18)O24—C25—C26111.09 (18)
O1—C10—C8113.59 (17)O24—C25—H25A109.4
O1—C10—C9121.98 (18)C26—C25—H25A109.4
C8—C10—C9124.43 (19)O24—C25—H25B109.4
C12—C11—C16118.3 (2)C26—C25—H25B109.4
C12—C11—C2121.07 (18)H25A—C25—H25B108.0
C16—C11—C2120.61 (19)O27—C26—O28124.2 (2)
C13—C12—C11120.9 (2)O27—C26—C25126.1 (2)
C13—C12—H12119.5O28—C26—C25109.75 (18)
C11—C12—H12119.5C26—O28—C29116.20 (18)
C14—C13—C12119.9 (2)O28—C29—H29A109.5
C14—C13—H13120.0O28—C29—H29B109.5
C12—C13—H13120.0H29A—C29—H29B109.5
C15—C14—C13119.9 (2)O28—C29—H29C109.5
C15—C14—H14120.0H29A—C29—H29C109.5
C13—C14—H14120.0H29B—C29—H29C109.5
C10—O1—C2—C3−0.2 (3)C4—C9—C10—C8178.82 (18)
C10—O1—C2—C11−178.52 (15)C3—C2—C11—C12165.1 (2)
O1—C2—C3—C4−2.6 (3)O1—C2—C11—C12−16.8 (3)
C11—C2—C3—C4175.34 (19)C3—C2—C11—C16−17.2 (3)
C2—C3—C4—O17−177.0 (2)O1—C2—C11—C16160.97 (18)
C2—C3—C4—C93.3 (3)C16—C11—C12—C13−1.9 (3)
O18—C5—C6—C7−179.33 (18)C2—C11—C12—C13175.95 (19)
C9—C5—C6—C70.4 (3)C11—C12—C13—C14−0.1 (3)
C5—C6—C7—O24−177.80 (18)C12—C13—C14—C151.9 (3)
C5—C6—C7—C80.5 (3)C13—C14—C15—C16−1.7 (4)
O24—C7—C8—C10177.02 (18)C14—C15—C16—C11−0.2 (4)
C6—C7—C8—C10−1.0 (3)C12—C11—C16—C152.0 (3)
O18—C5—C9—C10179.10 (16)C2—C11—C16—C15−175.8 (2)
C6—C5—C9—C10−0.7 (3)C6—C5—O18—C197.8 (3)
O18—C5—C9—C40.5 (3)C9—C5—O18—C19−171.99 (17)
C6—C5—C9—C4−179.34 (19)C5—O18—C19—C20−81.3 (2)
O17—C4—C9—C10179.1 (2)O18—C19—C20—O21−20.0 (3)
C3—C4—C9—C10−1.2 (3)O18—C19—C20—O22162.55 (15)
O17—C4—C9—C5−2.3 (3)O21—C20—O22—C23−13.6 (3)
C3—C4—C9—C5177.45 (19)C19—C20—O22—C23163.86 (19)
C2—O1—C10—C8−177.96 (16)C8—C7—O24—C258.3 (3)
C2—O1—C10—C92.3 (3)C6—C7—O24—C25−173.57 (18)
C7—C8—C10—O1−178.97 (17)C7—O24—C25—C2677.5 (2)
C7—C8—C10—C90.8 (3)O24—C25—C26—O27−6.8 (3)
C5—C9—C10—O1179.79 (16)O24—C25—C26—O28172.89 (16)
C4—C9—C10—O1−1.5 (3)O27—C26—O28—C292.7 (3)
C5—C9—C10—C80.1 (3)C25—C26—O28—C29−176.98 (18)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C19—H19A···O17i0.972.543.214 (3)127
C19—H19A···O18i0.972.583.366 (2)138
C29—H29A···Cg3ii0.963.063.765131
Symmetry codes: (i) −x+1, −y+1, −z; (ii) x+1, y, z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C19—H19A···O17i0.972.543.214 (3)127
C19—H19A···O18i0.972.583.366 (2)138
C29—H29A···Cg3ii0.963.063.765131
Symmetry codes: (i) −x+1, −y+1, −z; (ii) x+1, y, z.
Acknowledgements top

AN thanks Dr Naresh Kumar and Dr G. Vengatachalam, School of Chemistry, Bharathidasan University, Tiruchirappalli, and Organica Aromatics Pvt Ltd Bangalore, India, for providing laboratory facilities.

references
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