Carb­oxy­methyl ursolate monohydrate

Yan Zhong; ZhaoHui Dai; YanBo Teng; Bin Wu; JianPing Zhou

doi:10.1107/S1600536811001619

. 2011 Jan 15;67(Pt 2):o428. doi: 10.1107/S1600536811001619

Carboxymethyl ursolate monohydrate

Yan Zhong ^a,^b, ZhaoHui Dai ^c, YanBo Teng ^c, Bin Wu ^c, JianPing Zhou ^a,^*

PMCID: PMC3051648 PMID: 21523096

Abstract

In the title compound, C₂₈H₅₀O₅·H₂O, all of the six-membered rings of the pentacyclic triterpene skeleton adopt chair conformations. In the crystal, molecules are linked by O—H⋯O and C—H⋯O hydrogen bonds.

Related literature

For the synthesis, see: Wen et al. (2006 ▶). The crystal structure of ursolic acid is known from its ethanol solvate, see: Simon et al. (1992 ▶). For methyl uroslate-3-bromoacetate, see: Stout & Stevens (1963 ▶). For methyl ursolate-3-p-bromobenzoate, see: Paton & Paul (1979 ▶). For background to ursolic acid derivatives and their biological activity, see: Es-saady et al. (1996 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₃₂H₅₀O₅·H₂O
M _r = 532.74
Monoclinic,
a = 13.338 (3) Å
b = 8.1010 (16) Å
c = 14.311 (3) Å
β = 106.26 (3)°
V = 1484.5 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.976, T _max = 0.992
5692 measured reflections
5446 independent reflections
4536 reflections with I > 2σ(I)
R _int = 0.025
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.134
S = 1.00
5446 reflections
350 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994) ▶; cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); 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.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811001619/hb5787sup1.cif

e-67-0o428-sup1.cif^{(30.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811001619/hb5787Isup2.hkl

e-67-0o428-Isup2.hkl^{(266.6KB, 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
OW—HWB⋯O2ⁱ	0.85	2.41	2.839 (3)	112
OW—HWB⋯O4ⁱ	0.85	2.58	3.365 (3)	154
O1—H1A⋯O4ⁱⁱ	0.82	1.98	2.758 (3)	159
OW—HWA⋯O1ⁱⁱⁱ	0.86	1.88	2.681 (3)	154
O5—H5B⋯OW	0.85	1.74	2.575 (3)	165
C12—H12A⋯OWⁱ	0.93	2.57	3.455 (3)	159

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

The authors acknowledge support from the Natural Science Fundation of Jiangsu Province (No. BK2010538). The authors also thank Professor Hua-Qin Wang of the Analysis Centre, Nanjing University, for collecting the crystallographic data.

supplementary crystallographic information

Experimental

To a solution of ursolic acid (5.0 g, 11 mmol) in DMF (125 ml) were added ethyl chloroacetate (1.17 ml, 11 mmol) and K2CO3 (4.5 g, 33 mmol). The reaction mixture was stirred at room temperature for 5 h, then filtered and concentrated to give ethoxycarbonylmethyl ursolate as a yellow oil, which is pure enough for the next step. The ester was dissolved in MeOH (50 ml), THF (75 ml) and 4 N NaOH (30 ml). The mixture was stirred at room temperature for 18 h. After solvent evaporation under reduced pressure, H2O (90 ml) was added. The mixture was acidified with 4 N HCl until the pH was adjusted to 3.0 and the product was extracted with CHCl₃ (75 ml). The organic layer was separated and dried in Na₂SO₄. Filtration and concentration under reduce pressure provided carboxymethyl ursolate as a white powder. The colorless block of the title compound used in x-ray diffraction studies were grown in a mixture of ethyl acetate and hexane by a slow evaporation at room temperature.