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

Angannan Nallasivam; Munirathinam Nethaji; Nagarajan Vembu; Buckle Jaswant; Nagarajan Sulochana

doi:10.1107/S1600536809001019

. 2009 Jan 14;65(Pt 2):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

Angannan Nallasivam ^a, Munirathinam Nethaji ^b, Nagarajan Vembu ^c,^*, Buckle Jaswant ^d, Nagarajan Sulochana ^a

PMCID: PMC2968320 PMID: 21581921

Abstract

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.

Related literature

For the second polymorph, 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 ▶).For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶); Desiraju & Steiner (1999 ▶); Etter (1990 ▶).

Experimental

Crystal data

C₂₁H₁₈O₈
M _r = 398.35
Triclinic,
a = 9.4024 (16) Å
b = 9.8506 (17) Å
c = 11.1570 (18) Å
α = 67.817 (3)°
β = 80.300 (3)°
γ = 89.683 (3)°
V = 941.3 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 (2) K
0.42 × 0.35 × 0.29 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1998 ▶) T _min = 0.955, T _max = 0.969
8351 measured reflections
4316 independent reflections
2424 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.055
wR(F ²) = 0.140
S = 0.98
4316 reflections
264 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); 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, 2003 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809001019/fb2124sup1.cif

e-65-0o314-sup1.cif^{(21.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809001019/fb2124Isup2.hkl

e-65-0o314-Isup2.hkl^{(211.5KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C19—H19A⋯O17ⁱ	0.97	2.54	3.214 (3)	127
C19—H19A⋯O18ⁱ	0.97	2.58	3.366 (2)	138

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Symmetry codes: (i) Inline graphic .

Acknowledgments

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.

supplementary crystallographic information

Comment

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.

Experimental

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%