4-Oxo-2-phenylchroman-6-yl propionate

Edyta Kostrzewa-Susłow; Agata Białońska; Tomasz Janeczko

doi:10.1107/S1600536810012298

. 2010 May 22;66(Pt 6):o1401. doi: 10.1107/S1600536810012298

4-Oxo-2-phenylchroman-6-yl propionate

Edyta Kostrzewa-Susłow ^a, Agata Białońska ^b,^*, Tomasz Janeczko ^a

PMCID: PMC2979424 PMID: 21579480

Abstract

In the structure of the title compound, C₁₈H₁₆O₄, both the S and R enantiomers appear to occupy in a random way four symmetry-equivalent sites of the unit cell in an approximately 4:1/1:4 ratio. The chiral C atom of the pyrone ring together with the phenyl ring bonded to this atom are disordered over two positions, the occupancy factor of the major component being 0.809 (5). Adjacent molecules are linked by weak C—H⋯O hydrogen bonds.

Related literature

For background to flavonoids and their properties, see: Harborne & Baxter (1999 ▶); Harborne & Williams (2000 ▶); Di Carlo et al.,(1999 ▶); Rice-Evans (2004 ▶); Wang (2000 ▶); Halliwell (1996 ▶); Rice-Evans et al. (1996 ▶); Kostrzewa-Susłow et al. (2008 ▶). For related structures, see: Shoja et al. (1998 ▶); Białońska et al. (2007 ▶).

Experimental

Crystal data

C₁₈H₁₆O₄
M _r = 296.31
Monoclinic,
a = 7.863 (2) Å
b = 17.876 (4) Å
c = 10.731 (2) Å
β = 101.28 (3)°
V = 1479.2 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.32 × 0.15 × 0.09 mm

Data collection

Kuma KM4 CCD diffractometer
23501 measured reflections
5512 independent reflections
1906 reflections with I > 2σ(I)
R _int = 0.126

Refinement

R[F ² > 2σ(F ²)] = 0.063
wR(F ²) = 0.140
S = 0.86
5512 reflections
263 parameters
186 restraints
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: CrysAlis CCD, (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2009 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XP (Bruker, 1999 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810012298/hg2666sup1.cif

e-66-o1401-sup1.cif^{(22.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810012298/hg2666Isup2.hkl

e-66-o1401-Isup2.hkl^{(269.9KB, 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
C2—H2⋯O18ⁱ	1.00	2.37	3.145 (3)	133

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Symmetry code: (i) Inline graphic .

Acknowledgments

Publication/Project "Biotransformations for pharmaceutical and cosmetics industry" No. POIG.01.03.01-00-158/09-00 was part-financed by the European Union within the European Regional Development Fund.

supplementary crystallographic information

Comment

Flavonoids, which are the subject of our research, are biologically active substances naturally occuring in plants. The colour of flowers and leaves and its intensity is correlated with their presence. Due to the strong UV absorption, flavonoids play protective role in plants. They are also nectar indicators. Flavonoids protect plants from pathogens, act as inhibitors of auxins transport and also initiate formation of root nodules in papilionaceous plants [Harborne & Baxter, 1999; Harborne & Williams, 2000].

So far, flavonoids have not been found in organisms of animals and humans, however worldwide research proved wide range of valuable biological activities of these compounds. These include antiallergic, antiatherogenic, antidiabetic, antidiarrheic, antiinflammatory, antihepatotoxic and anticancerogenic properties [Di Carlo et al., 1999; Rice-Evans, 2004; Wang, 2000]. The wide spectrum of their pharmacological activities depends on chemical structures. Especially important is presence of carbonyl group, as well as presence, number and location of hydroxyl groups. For example, the presence of hydroxyl groups in the B ring is the main factor determining antioxidant activity of flavonoids [Halliwell, 1996; Rice-Evans et al., 1996].

Transformation of flavonoids by means of microorganisms is a way of modification of their structure, as well as a helpful tool for elucidation of their metabolism in mammals [Kostrzewa-Susłow et al., 2008].

The crystal structure of 6-propionoxyflavanone, together with numbering scheme employed, is presented in Fig. 1. In the present analysis, atoms at position 2 in the pyrone ring [C2 and H2 (major component) and C2A and H2A (minor component)] and phenyl ring [C11—C16 (major component) and C11A—C16A (minor component)] are clearly resolved. The C11—C16 (or C11A—C16A) phenyl ring is oriented almost perpendicular to the plane of the C5—C10 arene ring. The angle between the plane of the C11—C16 (C11A—C16A) ring and the plane of the C5—C10 ring is equal to 79.79 (12) ° (89.8 (5) °). The angle between the plane of carboxylate group and the plane of the C5—C10 ring is equal to 75.62 (8) °. The O1, C3, C4 O17 atoms are situated approximately in the plane of the C5—C10 arene ring (maximum deviation is equal to 0.040 (3) Å for O1). While deviation of the C18 and C2 atoms from the plane formed by the C5—C10 arene ring are equal to 1.140 (4) and 0.676 (4) Å, respectively, deviation of the C2A atom from the plane is equal to -0.403 (13) Å. Thus, two enantiomers revealing various conformations occupy equivalent sites, however somewhat randomly, not systematically, arranged in the unit cell. The ratio of the two enantiomers (R:S) in an asymmetric part of the unit cell is approximately equal to 0.8:0.2, which gives a 4:1/1:4 ratio in the crystal structure overall.

Experimental

The title compound was obtained during esterification of 6-hydroksyflavanone using propionyl chloride (Fig.2). Crystals of 6-propionoxyflavanone were grown from a THF (tetrahydrofurane) solution under ambient conditions.