Methyl 5,7-dihydr­oxy-2,2,9-trimethyl-6,11-dioxo-6,11-dihydro-2H-anthra[2,3-b]pyran-8-carboxyl­ate

Noungoue Tchamo, D.; Brelot, L.; Antheaume, C.; Ngouela, S.; Lobstein, A.

doi:10.1107/S160053680803794X

Volume 64
Part 12
Pages o2414-o2415
December 2008

Received 30 September 2008
Accepted 14 November 2008
Online 22 November 2008

Key indicators
Single-crystal X-ray study
T = 173 K
Mean (C-C) = 0.003 Å
R = 0.072
wR = 0.171
Data-to-parameter ratio = 15.1
Details

Methyl 5,7-dihydroxy-2,2,9-trimethyl-6,11-dioxo-6,11-dihydro-2H-anthra[2,3-b]pyran-8-carboxylate

Diderot Noungoue Tchamo,^a ^* Lydia Brelot,^b Cyril Antheaume,^c Silvère Ngouela ^a and Annelise Lobstein ^d

^aDepartment of Organic Chemistry, Faculty of Science, University of Yaoundé I, P.O. Box 812 Yaoundé, Cameroon,^bInstitut de Chimie de Strasbourg, Université Louis Pasteur, Service de Radiocristallographie, UMR 7177 CNRS, 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France,^cLaboratory of NMR, LC1 IFR85, University Louis Pasteur, Faculty of Pharmacy, Strasbourg, France, and ^dLaboratory of Pharmacognosy, LC1 UMR-CNRS 7175, University Louis Pasteur, Faculty of Pharmacy, Strasbourg, France
Correspondence e-mail: didetchamo@yahoo.fr

The title compound, C₂₂H₁₈O₇, also known as laurentiquinone B, is a new anthraquinone which was isolated from Vismia laurentii, a Cameroonian medicinal plant. The asymmetric unit contains two independent molecules. Each of them contains four fused rings, three of which are coplanar and typical of anthracene, while the heterocyclic rings adopt envelope conformations. Intramolecular O-HO hydrogen bonds result in the formation of two planar rings, which are also almost coplanar with the adjacent rings. In the crystal structure, intermolecular O-HO and C-HO hydrogen bonds link the molecules and a [pi] - [pi] contact is also present [centroid-centroid distance = 3.967 (3) Å].

Related literature

For the biosynthesis of anthraquinones, see: Birch et al. (1965); Shibata & Ikekawa (1963). For the bioactivity of anthraquinones, see: ; Adwankar & Chitnis (1982); Sittie et al. (1999); Rath et al. (1995); Ismail et al. (1997); Nagem & de Oliveira (1997); Nguemeving et al. (2006). For the pharmacology of Vismia laurentii, see: Kerharo (1974); Macfoy & Sama (1983). For other classes of natural products isolated from Vismia species, see: Simmonds et al. (1985); Nagem & de Oliveira (1997); Seo et al. (2000); Nguemeving et al. (2006). For related structures, see: Noungoue et al. (2008).

Experimental

Crystal data

C₂₂H₁₈O₇
M_r = 394.36
Triclinic, $[P \overline 1]$
a = 6.9234 (4) Å
b = 16.0765 (9) Å
c = 17.5304 (9) Å
= 108.746 (2)°
= 98.725 (3)°
= 94.147 (2)°
V = 1810.97 (17) Å³
Z = 4
Mo K radiation
= 0.11 mm^-1
T = 173 (2) K
0.30 × 0.20 × 0.15 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: none
17235 measured reflections
8260 independent reflections
4538 reflections with I > 2(I)
R_int = 0.062

Refinement

R[F² > 2(F²)] = 0.072
wR(F²) = 0.171
S = 1.02
8260 reflections
547 parameters
H atoms treated by a mixture of independent and constrained refinement
_max = 0.28 e Å^-3
_min = -0.25 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
O4-H4OO3	0.91 (3)	1.72 (3)	2.567 (2)	152 (3)
O11-H11OO10	0.88 (3)	1.75 (4)	2.568 (2)	153 (3)
O9-H9OO10	0.92 (3)	1.72 (3)	2.558 (2)	150 (3)
O2-H2OO3	0.88 (3)	1.77 (3)	2.562 (2)	148 (3)
O2-H20O9ⁱ	0.88 (3)	2.31 (3)	2.654 (2)	103 (2)
C34-H34O7ⁱⁱ	0.95	2.59	3.441 (2)	150
C44-H44BO7ⁱⁱ	0.98	2.51	3.423 (2)	155
C44-H44CO8ⁱⁱ	0.98	2.58	3.419 (2)	144
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) -x+1, -y+1, -z.

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; 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 data and figures for this paper are available from the IUCr electronic archives (Reference: HK2545 ).

Acknowledgements

The authors thank the `Service de Coopération et d'Action Culturelle de l'Ambassade de France au Cameroun' for a fellowship awarded to DNT at ULP Strasbourg and also J. Kister for his help to crystallize the compound.

References

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organic compounds