rac-(1S,2R)-Diethyl 6-hydr­oxy-1-(4-methoxy­phen­yl)-3-oxo-2,3-di­hydro-1H-benzo[f]chromen-2-yl]­phospho­nate

Jakub Wojciechowski; Henryk Krawczyk; Łukasz Albrecht; Wojciech M Wolf

doi:10.1107/S1600536808015857

. 2008 Jun 7;64(Pt 7):o1240–o1241. doi: 10.1107/S1600536808015857

rac-(1S,2R)-Diethyl 6-hydroxy-1-(4-methoxyphenyl)-3-oxo-2,3-dihydro-1H-benzo[f]chromen-2-yl]phosphonate

Jakub Wojciechowski ^a, Henryk Krawczyk ^b, Łukasz Albrecht ^b, Wojciech M Wolf ^a,^*

PMCID: PMC2961657 PMID: 21202876

Abstract

In the title compound, C₂₄H₂₅O₇P, the δ-valerolactonyl ring exists in a distorted screw-boat conformation with the diethoxyphosphoryl substituent occupying an axial position. The latter adopts an almost syn-periplanar conformation around the P—C bond. The molecules form centrosymmetric dimers connected by O—H⋯O hydrogen bonds.

Related literature

For the biological activity of 4-aryl-3,4-dihydrocoumarins, see: Bailly et al. (2003 ▶); Roelens et al. (2005 ▶); Zhang et al. (2006 ▶). For their synthesis, see: Aoki et al. (2005 ▶); Krawczyk et al. (2007a ▶); Li et al. (2005 ▶); Rizzi et al. (2006 ▶). For a comparison structure, see: Krawczyk et al. (2007b ▶).

For the atomic charges fitted to electrostatic potential, see: Frisch et al. (2004 ▶); Breneman & Wiberg (1990 ▶). For repulsive interactions between O atoms, see: Gillespie & Popelier, (2001 ▶). For hydrogen-bond graph-set terminology, see: Bernstein et al. (1995 ▶); Etter (1990 ▶). For ring puckering analysis, see: Boeyens (1978 ▶); Cremer & Pople (1975 ▶); Frisch et al. (2004 ▶). For details of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₂₄H₂₅O₇P
M _r = 456.41
Monoclinic,
a = 21.6231 (17) Å
b = 10.0018 (8) Å
c = 22.4011 (17) Å
β = 111.806 (1)°
V = 4498.0 (6) Å³
Z = 8
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 293 (2) K
0.30 × 0.20 × 0.15 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T _min = 0.951, T _max = 0.976
37601 measured reflections
5076 independent reflections
3585 reflections with I > 2σ(I)
R _int = 0.043

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.137
S = 1.05
5076 reflections
310 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT-Plus (Bruker, 2003 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL and publCIF (Westrip, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808015857/ng2458sup1.cif

e-64-o1240-sup1.cif^{(23.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808015857/ng2458Isup2.hkl

e-64-o1240-Isup2.hkl^{(308.1KB, hkl)}

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

Enhanced figure: interactive version of Fig. 4

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H6⋯O4ⁱ	0.83	1.87	2.701 (2)	178

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Symmetry code: (i) Inline graphic .

Acknowledgments

Atomic charges were calculated in the ACK CYFRONET, Kraków, Poland; support through computational grants 055/1999 and 056/1999 is gratefully acknowledged.

supplementary crystallographic information

Comment

The 4-aryl-3,4-dihydrocoumarin (neoflavonoid) moiety is found in several natural compounds which show a wide range of biological activities. Among them, the anti-inflammatory, anti-oxidative and anti-aging properties are best recognized (Zhang et al., 2006). A number of neoflavonoids isolated from various plant sources revealed cytotoxic and chemopreventive activity against cancer (Bailly et al., 2003). Morever, some 4-aryl-3,4-dihydrocoumarin derivatives exhibit estrogenic activity (Roelens et al., 2005). The most common method for the synthesis of 4-aryl-3,4-dihydrocoumarins involves Michael type addition of electron-rich hydroxyarenes to cinnamic acids or their derivatives (Aoki et al., 2005; Li et al., 2005; Rizzi et al., 2006). Unfortunately this method is limited to the reactions of cinnamic acid bearing electron-donationg groups on the aromatic ring. Recently we developed a novel synthesis of the dihydrocoumarins based on CF₃SO₃H promoted Friedel Crafts reaction of electron-rich hydroxyarenes (Krawczyk et al., 2007a) with the (E)-3-aryl-2-(diethoxyphosphoryl)acrylic acids. The title compound (I) is a key product of that synthesis.

The title compound (I) represents a novel dihydrocoumarine analog in which the δ-valerolactone ring bears the P—C bond. A related compound (II) in which the electron-donating para-methoxy substituent was replaced by the electron-withdrawing Br atom has been published by us recently (Krawczyk et al., 2007b). A search of the Cambridge Structural Database (Version 5.29; Allen, 2002) showed that crystal structures of the related compounds have not been reported so far.

A view of (I), with atom numbering scheme is shown in Fig. 1. The δ-valerolactone and naphtalene moieties are almost coplanar with one another. The former ring adopts conformation close to a ⁴S₃ screw-boat (Boeyens, 1978), with O1, C1, C3, C4 and C9 almost coplanar (the average r.m.s. deviation from the mean plane is 0.09 Å) and C2 situated at the flap. The Cremer & Pople (1975) puckering parameters for the ring atom sequence O1/C1/C2/C3/C4/C9 are: Q = 0.489 (2) Å, θ = 113.6 (2)° and φ = 327.5 (3)°. Both exocyclic substituents, namely the diethoxyphosphoryl and phenyl groups occupy axial positions in respect to the δ-valerolactone ring.

The former group adopts an almost synperiplanar conformation along the P—C2 bond (Fig. 2). This arrangement is stabilized by electrostatic interactions of the oppositely charged phosphoryl O4 (-0.70 e) with the carbonyl C1 (0.79 e) atoms [the C1···O2 distance is 2.966 (2) Å] Atomic charges derived from electrostatic potentials were calculated using GAUSSIAN03 (Frisch et al., 2004) at the MP2/6-311++G(d,p) level for the X-ray determined coordinates. Grid points were selected according to the CHELPG procedure of Breneman & Wiberg (1990).

The phosphorus atom is located within the center of distorted tetrahedron with valency angles ranging in value from 99.90 (9) to 115.74 (11)°. On average the O—P—O type angles [111.6 (2)°] are larger then O—P—C [106.9 (2)°]. This is a general feature, often encountered in phosphorus compounds, indicating a significance of repulsive Coulombic type interactions between the oxygen atoms bearing the negative charge (Gillespie & Popelier, 2001).

A superposition of structures (I) and (II), as presented in Fig. 3, clearly shows similarity of the neoflavonoid fragments. The major difference is position of the O5—C22—C23 diethoxy group. In (I) this group points away from the naphtalene fragment while in (II) it is almost paralel and involved in the C—H—π(arom) interaction. The latter stabilizes a virtual eclipsed conformation along the axial P—C bond as was found in (II).

In the crystal molecules form centrosymmetric dimers connected by strong, practically linear hydrogen bonds linking phosphoryl and hydroxyl groups of both monomers. In terms of Etter's graph-set terminology (Etter, 1990; Bernstein, et al., 1995) this system can be described as R²₂(20).

Experimental

The solution 1,3-dihydroxynaphtalene in CH₂Cl₂, trifluoromethanesulfonic acid and (E)-2-diethoxyphosphoryl-3-(4-methoxyphenyl)acrylic acid were added and a resulting mixture was left at room temperature for 1 day. After the acrylic acid was completely reacted, saturated NaHCO₃ solution was added. The organic layer was separated, washed with water and dried over MgSO₄. Evaporation of the solvent under reduced preasure gave a crude product which was purified by column chromatography and recrystalized from diethyl ether.