1-Hydr­oxy-3-(3-methyl­but-2-en­yloxy)xanthone

Gales, L.; Castanheiro, R.A.P.; Pinto, M.M.M.; Damas, A.M.

doi:10.1107/S1600536809040069

organic compounds

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ISSN: 2056-9890

Volume 65| Part 11| November 2009| Pages o2718-o2719

https://doi.org/10.1107/S1600536809040069

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1-Hydroxy-3-(3-methylbut-2-enyloxy)xanthone

Luis Gales,^a Raquel A. P. Castanheiro,^b Madalena M. M. Pinto ^b and Ana M. Damas ^a ^*

^aInstituto de Biologia Molecular e Celular, & Instituto de Ciências Biomédicas Abel Salazar, Portugal, and ^bCentro de Química Medicinal da Universidade do Porto (CEQUIMED–UP), e Serviço de Química Orgânica, Faculdade de Farmácia, Universidade do Porto, Portugal
^*Correspondence e-mail: amdamas@ibmc.up.pt

(Received 24 July 2009; accepted 1 October 2009; online 13 October 2009)

In the title compound, C₁₈H₁₆O₄, a monoprenylated xanthone, the xanthone skeleton exhibits an essentially planar conformation (r.m.s. deviation 0.0072 Å) and the isoprenyl side chain remains approximately in the mean plane of the xanthone unit, making a dihedral angle of 4.5 (2)°. The hydroxyl group forms an intramolecular O—H⋯O hydrogen bond. Moreover, there is a weak intermolecular C—H⋯O interaction between a ring C atom and the xanthene O atom. In the crystal structure, there are no intermolecular hydrogen bonds and the crystallographic packing is governed by van der Waals forces, leading to an arrangement in which the molecules assemble with their planes parallel to each other, having a separation of 3.6 (3) Å.

Related literature

For a review of the biological activity of prenylated xanthones, see: Pinto et al. (2005 ). For background literature and synthesis of prenylated xanthones, see: Pinto et al. (2005); Epifano et al. (2007 ); Castanheiro et al. (2007 ). For the synthesis of the title compound using microwave radiation, see: Castanheiro et al. (2009 ). For analysis of related structures of xanthone derivatives, see: Gales et al. (2001 , 2005 a,b); Castanheiro et al. (2007). For the interaction with biological membranes and target proteins, see: Maia et al. (2005 ); Epifano et al. (2007). For a review of prenylated xanthone crystal structures, see: Gales & Damas, 2005 ).

Experimental

Crystal data

C₁₈H₁₆O₄
M_r = 296.31
Triclinic, $[P \overline 1]$
a = 4.8199 (3) Å
b = 11.7014 (8) Å
c = 13.6176 (10) Å
α = 77.329 (6)°
β = 88.582 (6)°
γ = 79.039 (6)°
V = 735.54 (9) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 295 K
0.4 × 0.2 × 0.1 mm

Data collection

Oxford Diffraction Gemini PX Ultra CCD area-detector diffractometer
Absorption correction: none
8520 measured reflections
2981 independent reflections
1958 reflections with I > 2σ(I)
R_int = 0.017

Refinement

R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.147
S = 1.07
2981 reflections
202 parameters
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯O11	0.82	1.85	2.5846 (17)	148
C5—H5A⋯O2ⁱ	0.93	2.60	3.514 (2)	168
Symmetry code: (i) -x+1, -y+2, -z+1.

Data collection: CrysAlis CCD (Oxford Diffraction, 2004 $[Oxford Diffraction (2004). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2004 $[Oxford Diffraction (2004). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Johnson & Burnett, 1996 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536809040069/bv2126sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536809040069/bv2126Isup2.hkl

checkCIF report

Comment top

Prenylated xanthones have been reported to mediate a number of important biological activities, concerning a large variety of targets with therapeutic value. The presence of the prenyl side chains seems to enhance the interaction with biological membranes and with target proteins (Maia et al., 2005 and Epifano et al., 2007) and we plan to further study these kind of interactions.

However, the synthesis of prenylated xanthones usually involves toxic reagents and is considered not only very demanding but also environmentally unfriendly (Castanheiro et al., 2007). We have looked for an alternative method to obtain prenylated xanthones. The title compound was the first example of a prenylated xanthone synthesized by the microwave irradiation method (Castanheiro et al., 2009). In fact, microwave-assisted heating under controlled conditions is an invaluable technology for medicinal chemistry because it often dramatically reduces reaction times.

In the crystal, the title compound molecules are essentially planar (Fig. 1). The isoprenyl side chain adopts a nearly coplanar conformation relatively to the xanthone skeleton (corresponding dihedral angle 4.5 (2)°). This is an exception because in the crystal structures of other prenylated xanthones, the isoprenyl side chain is usually out of the plane of the xanthones moiety (for a review of prenylated xanthone crystal structures see: Gales & Damas, 2005). Moreover, the hydroxyl substituent bound to C1 forms a strong intramolecular hydrogen bond to O11 [O1—H1A···O11 = 2.5845 (17) Å].

In the crystal structure, the title compound forms stacking planes (Fig. 2) with intermolecular separation of 3.6 Å. The packing of the molecules is governed by van der Waals forces and there are no intermolecular hydrogen bonds.

Related literature top

For a review of the biological activity of prenylated xanthones, see: Pinto et al. (2005). For background literature and synthesis of prenylated xanthones, see: Pinto et al. (2005); Epifano et al. (2007); Castanheiro et al. (2007). For the synthesis of the title compound using microwave radiation, see: Castanheiro et al. (2009). For analysis of related structures of xanthone derivatives, see: Gales et al. (2001, 2005a,b); Castanheiro et al. (2007). For the interaction with biological membranes and target proteins, see: Maia et al. (2005); Epifano et al. (2007). For a review of prenylated xanthone crystal structures, see: Gales & Damas, 2005).

Experimental top

Prenylation was carried out using prenyl bromide in alkaline medium under microwave irradiation according to the procedure reported by Castanheiro et al. (2009). Single crystals suitable for X-ray crystallographic analysis were grown by recrystallization from slow evaporation of a CH₂Cl₂/PE (60–80) solution.

Structure description top

For a review of the biological activity of prenylated xanthones, see: Pinto et al. (2005). For background literature and synthesis of prenylated xanthones, see: Pinto et al. (2005); Epifano et al. (2007); Castanheiro et al. (2007). For the synthesis of the title compound using microwave radiation, see: Castanheiro et al. (2009). For analysis of related structures of xanthone derivatives, see: Gales et al. (2001, 2005a,b); Castanheiro et al. (2007). For the interaction with biological membranes and target proteins, see: Maia et al. (2005); Epifano et al. (2007). For a review of prenylated xanthone crystal structures, see: Gales & Damas, 2005).

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2004); cell refinement: CrysAlis CCD (Oxford Diffraction, 2004); data reduction: CrysAlis RED (Oxford Diffraction, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Johnson & Burnett, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title compound, with atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. The packing of the title compound, showing parallel stacking planes 3.6Å apart. H atoms have been omitted.

1-Hydroxy-3-(3-methylbut-2-enyloxy)xanthone top

Crystal data top

C₁₈H₁₆O₄	Z = 2
M_r = 296.31	F(000) = 312
Triclinic, P1	D_x = 1.338 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 4.8199 (3) Å	Cell parameters from 1141 reflections
b = 11.7014 (8) Å	θ = 4.0–24.3°
c = 13.6176 (10) Å	µ = 0.09 mm⁻¹
α = 77.329 (6)°	T = 295 K
β = 88.582 (6)°	Plate, yellow
γ = 79.039 (6)°	0.4 × 0.2 × 0.1 mm
V = 735.54 (9) Å³

Data collection top

Oxford Diffraction Gemini PX Ultra CCD area-detector diffractometer	1958 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.017
Graphite monochromator	θ_max = 26.4°, θ_min = 2.6°
ω and θ scans	h = −5→6
8520 measured reflections	k = −14→14
2981 independent reflections	l = −17→16

Refinement top

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)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.147	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0771P)² + 0.0559P] where P = (F_o² + 2F_c²)/3
2981 reflections	(Δ/σ)_max < 0.001
202 parameters	Δρ_max = 0.16 e Å⁻³
0 restraints	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₁₈H₁₆O₄	γ = 79.039 (6)°
M_r = 296.31	V = 735.54 (9) Å³
Triclinic, P1	Z = 2
a = 4.8199 (3) Å	Mo Kα radiation
b = 11.7014 (8) Å	µ = 0.09 mm⁻¹
c = 13.6176 (10) Å	T = 295 K
α = 77.329 (6)°	0.4 × 0.2 × 0.1 mm
β = 88.582 (6)°

Data collection top

Oxford Diffraction Gemini PX Ultra CCD area-detector diffractometer	1958 reflections with I > 2σ(I)
8520 measured reflections	R_int = 0.017
2981 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.048	0 restraints
wR(F²) = 0.147	H-atom parameters constrained
S = 1.07	Δρ_max = 0.16 e Å⁻³
2981 reflections	Δρ_min = −0.15 e Å⁻³
202 parameters

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

	x	y	z	U_iso*/U_eq
O1	0.2991 (3)	0.54781 (11)	0.38058 (10)	0.0702 (4)
H1A	0.4106	0.5456	0.3343	0.105*
O2	0.0013 (3)	0.78593 (11)	0.61948 (9)	0.0652 (4)
O10	0.6160 (2)	0.91544 (10)	0.36924 (8)	0.0558 (3)
O11	0.6489 (3)	0.62252 (12)	0.24577 (10)	0.0734 (4)
C1	0.3046 (3)	0.64516 (14)	0.41726 (13)	0.0525 (4)
C2	0.1471 (3)	0.66156 (14)	0.50003 (12)	0.0538 (4)
H2A	0.0408	0.6055	0.5307	0.065*
C3	0.1479 (3)	0.76265 (15)	0.53766 (12)	0.0518 (4)
C4	0.3038 (3)	0.84872 (15)	0.49224 (12)	0.0538 (4)
H4A	0.3000	0.9171	0.5168	0.065*
C4A	0.4623 (3)	0.82954 (14)	0.41054 (11)	0.0480 (4)
C5	0.9287 (4)	0.99283 (16)	0.25015 (13)	0.0612 (5)
H5A	0.9186	1.0567	0.2813	0.073*
C6	1.0918 (4)	0.98563 (18)	0.16677 (14)	0.0689 (5)
H6A	1.1906	1.0462	0.1408	0.083*
C7	1.1124 (4)	0.89031 (18)	0.12043 (14)	0.0694 (5)
H7A	1.2247	0.8870	0.0642	0.083*
C8	0.9666 (4)	0.80095 (17)	0.15780 (13)	0.0634 (5)
H8A	0.9809	0.7367	0.1269	0.076*
C8A	0.7966 (3)	0.80542 (15)	0.24201 (12)	0.0520 (4)
C9	0.6388 (3)	0.71111 (15)	0.28351 (13)	0.0546 (4)
C9A	0.4708 (3)	0.72862 (14)	0.36983 (12)	0.0487 (4)
C10A	0.7792 (3)	0.90220 (15)	0.28679 (12)	0.0516 (4)
C1X	−0.1460 (4)	0.69521 (16)	0.67349 (13)	0.0652 (5)
H1XA	−0.0128	0.6219	0.6991	0.078*
H1XB	−0.2807	0.6790	0.6290	0.078*
C2X	−0.2946 (4)	0.74034 (17)	0.75770 (14)	0.0716 (5)
H2XA	−0.3558	0.8224	0.7476	0.086*
C3X	−0.3486 (4)	0.67573 (16)	0.84547 (13)	0.0642 (5)
C4AX	−0.5155 (5)	0.7288 (2)	0.92405 (18)	0.0985 (8)
H4AA	−0.5531	0.8142	0.9028	0.148*
H4AB	−0.4096	0.7055	0.9863	0.148*
H4AC	−0.6910	0.7007	0.9334	0.148*
C4BX	−0.2550 (6)	0.5424 (2)	0.87218 (17)	0.1053 (8)
H4BA	−0.1111	0.5186	0.8268	0.158*
H4BB	−0.4135	0.5052	0.8669	0.158*
H4BC	−0.1808	0.5184	0.9399	0.158*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0865 (9)	0.0539 (7)	0.0832 (9)	−0.0265 (6)	0.0115 (7)	−0.0323 (6)
O2	0.0812 (8)	0.0638 (8)	0.0629 (7)	−0.0349 (6)	0.0260 (6)	−0.0248 (6)
O10	0.0642 (7)	0.0533 (7)	0.0592 (7)	−0.0242 (5)	0.0179 (5)	−0.0229 (5)
O11	0.0800 (8)	0.0676 (8)	0.0872 (9)	−0.0196 (7)	0.0159 (7)	−0.0447 (7)
C1	0.0567 (9)	0.0432 (9)	0.0611 (10)	−0.0120 (7)	−0.0055 (8)	−0.0158 (7)
C2	0.0588 (10)	0.0490 (10)	0.0579 (10)	−0.0207 (8)	0.0024 (8)	−0.0118 (8)
C3	0.0562 (9)	0.0508 (10)	0.0519 (9)	−0.0157 (7)	0.0032 (7)	−0.0145 (7)
C4	0.0635 (10)	0.0489 (9)	0.0579 (9)	−0.0211 (8)	0.0108 (8)	−0.0229 (8)
C4A	0.0511 (9)	0.0435 (9)	0.0530 (9)	−0.0138 (7)	0.0024 (7)	−0.0140 (7)
C5	0.0684 (11)	0.0575 (10)	0.0618 (10)	−0.0196 (9)	0.0132 (8)	−0.0161 (8)
C6	0.0727 (12)	0.0681 (12)	0.0644 (11)	−0.0201 (10)	0.0158 (9)	−0.0071 (9)
C7	0.0728 (12)	0.0791 (14)	0.0542 (10)	−0.0099 (10)	0.0166 (9)	−0.0157 (9)
C8	0.0668 (11)	0.0676 (12)	0.0573 (10)	−0.0061 (9)	0.0053 (9)	−0.0229 (9)
C8A	0.0504 (9)	0.0562 (10)	0.0503 (9)	−0.0056 (7)	0.0025 (7)	−0.0174 (8)
C9	0.0542 (9)	0.0522 (10)	0.0617 (10)	−0.0063 (7)	−0.0029 (8)	−0.0241 (8)
C9A	0.0476 (8)	0.0463 (9)	0.0545 (9)	−0.0088 (7)	−0.0027 (7)	−0.0160 (7)
C10A	0.0525 (9)	0.0540 (10)	0.0492 (9)	−0.0100 (7)	0.0050 (7)	−0.0140 (7)
C1X	0.0767 (12)	0.0563 (11)	0.0664 (11)	−0.0262 (9)	0.0178 (9)	−0.0117 (9)
C2X	0.0800 (13)	0.0569 (11)	0.0794 (13)	−0.0187 (9)	0.0279 (10)	−0.0161 (10)
C3X	0.0750 (12)	0.0612 (11)	0.0605 (10)	−0.0236 (9)	0.0129 (9)	−0.0141 (9)
C4AX	0.1244 (19)	0.0849 (16)	0.0881 (15)	−0.0254 (14)	0.0440 (14)	−0.0225 (13)
C4BX	0.163 (2)	0.0746 (15)	0.0736 (14)	−0.0225 (15)	0.0266 (15)	−0.0095 (11)

Geometric parameters (Å, º) top

O1—C1	1.3453 (19)	C7—C8	1.369 (3)
O1—H1A	0.8200	C7—H7A	0.9300
O2—C3	1.3548 (19)	C8—C8A	1.397 (2)
O2—C1X	1.4460 (18)	C8—H8A	0.9300
O10—C10A	1.3744 (19)	C8A—C10A	1.388 (2)
O10—C4A	1.3748 (18)	C8A—C9	1.463 (2)
O11—C9	1.247 (2)	C9—C9A	1.440 (2)
C1—C2	1.371 (2)	C1X—C2X	1.479 (3)
C1—C9A	1.417 (2)	C1X—H1XA	0.9700
C2—C3	1.389 (2)	C1X—H1XB	0.9700
C2—H2A	0.9300	C2X—C3X	1.316 (2)
C3—C4	1.398 (2)	C2X—H2XA	0.9300
C4—C4A	1.369 (2)	C3X—C4AX	1.495 (3)
C4—H4A	0.9300	C3X—C4BX	1.504 (3)
C4A—C9A	1.404 (2)	C4AX—H4AA	0.9600
C5—C6	1.374 (2)	C4AX—H4AB	0.9600
C5—C10A	1.391 (2)	C4AX—H4AC	0.9600
C5—H5A	0.9300	C4BX—H4BA	0.9600
C6—C7	1.384 (3)	C4BX—H4BB	0.9600
C6—H6A	0.9300	C4BX—H4BC	0.9600

C1—O1—H1A	109.5	O11—C9—C9A	122.80 (16)
C3—O2—C1X	117.02 (13)	O11—C9—C8A	121.86 (16)
C10A—O10—C4A	119.38 (13)	C9A—C9—C8A	115.34 (15)
O1—C1—C2	118.92 (15)	C4A—C9A—C1	116.83 (15)
O1—C1—C9A	119.70 (15)	C4A—C9A—C9	121.62 (14)
C2—C1—C9A	121.37 (15)	C1—C9A—C9	121.55 (15)
C1—C2—C3	119.42 (15)	O10—C10A—C8A	123.03 (15)
C1—C2—H2A	120.3	O10—C10A—C5	115.61 (15)
C3—C2—H2A	120.3	C8A—C10A—C5	121.36 (15)
O2—C3—C2	123.65 (14)	O2—C1X—C2X	107.68 (14)
O2—C3—C4	115.03 (14)	O2—C1X—H1XA	110.2
C2—C3—C4	121.31 (15)	C2X—C1X—H1XA	110.2
C4A—C4—C3	118.15 (15)	O2—C1X—H1XB	110.2
C4A—C4—H4A	120.9	C2X—C1X—H1XB	110.2
C3—C4—H4A	120.9	H1XA—C1X—H1XB	108.5
C4—C4A—O10	116.23 (14)	C3X—C2X—C1X	126.38 (18)
C4—C4A—C9A	122.89 (14)	C3X—C2X—H2XA	116.8
O10—C4A—C9A	120.88 (14)	C1X—C2X—H2XA	116.8
C6—C5—C10A	118.31 (18)	C2X—C3X—C4AX	122.55 (19)
C6—C5—H5A	120.8	C2X—C3X—C4BX	122.09 (19)
C10A—C5—H5A	120.8	C4AX—C3X—C4BX	115.33 (16)
C5—C6—C7	121.54 (18)	C3X—C4AX—H4AA	109.5
C5—C6—H6A	119.2	C3X—C4AX—H4AB	109.5
C7—C6—H6A	119.2	H4AA—C4AX—H4AB	109.5
C8—C7—C6	119.64 (17)	C3X—C4AX—H4AC	109.5
C8—C7—H7A	120.2	H4AA—C4AX—H4AC	109.5
C6—C7—H7A	120.2	H4AB—C4AX—H4AC	109.5
C7—C8—C8A	120.57 (17)	C3X—C4BX—H4BA	109.5
C7—C8—H8A	119.7	C3X—C4BX—H4BB	109.5
C8A—C8—H8A	119.7	H4BA—C4BX—H4BB	109.5
C10A—C8A—C8	118.56 (16)	C3X—C4BX—H4BC	109.5
C10A—C8A—C9	119.75 (15)	H4BA—C4BX—H4BC	109.5
C8—C8A—C9	121.69 (16)	H4BB—C4BX—H4BC	109.5

O1—C1—C2—C3	−179.05 (15)	C4—C4A—C9A—C9	179.75 (14)
C9A—C1—C2—C3	0.7 (2)	O10—C4A—C9A—C9	−0.2 (2)
C1X—O2—C3—C2	4.5 (2)	O1—C1—C9A—C4A	178.64 (14)
C1X—O2—C3—C4	−175.47 (14)	C2—C1—C9A—C4A	−1.1 (2)
C1—C2—C3—O2	−179.37 (14)	O1—C1—C9A—C9	−0.9 (2)
C1—C2—C3—C4	0.6 (2)	C2—C1—C9A—C9	179.34 (14)
O2—C3—C4—C4A	178.50 (13)	O11—C9—C9A—C4A	−179.71 (15)
C2—C3—C4—C4A	−1.5 (2)	C8A—C9—C9A—C4A	−0.2 (2)
C3—C4—C4A—O10	−178.95 (13)	O11—C9—C9A—C1	−0.2 (2)
C3—C4—C4A—C9A	1.1 (2)	C8A—C9—C9A—C1	179.34 (13)
C10A—O10—C4A—C4	−179.75 (12)	C4A—O10—C10A—C8A	0.2 (2)
C10A—O10—C4A—C9A	0.2 (2)	C4A—O10—C10A—C5	−179.70 (13)
C10A—C5—C6—C7	−1.0 (3)	C8—C8A—C10A—O10	179.40 (14)
C5—C6—C7—C8	0.3 (3)	C9—C8A—C10A—O10	−0.7 (2)
C6—C7—C8—C8A	0.2 (3)	C8—C8A—C10A—C5	−0.7 (2)
C7—C8—C8A—C10A	−0.1 (2)	C9—C8A—C10A—C5	179.25 (15)
C7—C8—C8A—C9	−179.96 (15)	C6—C5—C10A—O10	−178.90 (14)
C10A—C8A—C9—O11	−179.85 (15)	C6—C5—C10A—C8A	1.2 (3)
C8—C8A—C9—O11	0.1 (3)	C3—O2—C1X—C2X	−178.84 (14)
C10A—C8A—C9—C9A	0.6 (2)	O2—C1X—C2X—C3X	−149.12 (19)
C8—C8A—C9—C9A	−179.45 (13)	C1X—C2X—C3X—C4AX	−176.29 (19)
C4—C4A—C9A—C1	0.2 (2)	C1X—C2X—C3X—C4BX	1.5 (3)
O10—C4A—C9A—C1	−179.79 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O11	0.82	1.85	2.5846 (17)	148
C5—H5A···O2ⁱ	0.93	2.60	3.514 (2)	168

Symmetry code: (i) −x+1, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₈H₁₆O₄
M_r	296.31
Crystal system, space group	Triclinic, P1
Temperature (K)	295
a, b, c (Å)	4.8199 (3), 11.7014 (8), 13.6176 (10)
α, β, γ (°)	77.329 (6), 88.582 (6), 79.039 (6)
V (Å³)	735.54 (9)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.4 × 0.2 × 0.1

Data collection
Diffractometer	Oxford Diffraction Gemini PX Ultra CCD area-detector
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	8520, 2981, 1958
R_int	0.017
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.147, 1.07
No. of reflections	2981
No. of parameters	202
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.15

Computer programs: CrysAlis CCD (Oxford Diffraction, 2004), CrysAlis RED (Oxford Diffraction, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Johnson & Burnett, 1996).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O11	0.82	1.85	2.5846 (17)	148.1
C5—H5A···O2ⁱ	0.93	2.60	3.514 (2)	167.9

Symmetry code: (i) −x+1, −y+2, −z+1.

Acknowledgements

The authors thank the Fundaçao para a Ciência e a Tecnologia (FCT), I&D Units 226/2003 (CEQOFFUP) and 4040/2007 (CEQUIMED), FEDER, POCI for financial support and the FCT (projects FCT /FEDER /POCI 2010 and PTDC/CTM/64191/2006) for the PhD grant to RC (SFRH/BD/13167/2003).

References

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