Tuberostemoamide hemihydrate

Rong-Rong Zhang; Zhi-Guo Ma; Guo-Qiang Li; Paul Pui-Hay But; Ren-Wang Jiang

doi:10.1107/S1600536811043340

. 2011 Oct 29;67(Pt 11):o3056. doi: 10.1107/S1600536811043340

Tuberostemoamide hemihydrate

Rong-Rong Zhang ^a, Zhi-Guo Ma ^a, Guo-Qiang Li ^a, Paul Pui-Hay But ^b, Ren-Wang Jiang ^a,^*

PMCID: PMC3247448 PMID: 22220066

Abstract

In the crystal structure of the title compound {systematic name: (1′S,2R,2′R,3′S,6′R)-3′-ethyl-4-methyl-5H-5′-oxa-10′-azaspiro[furan-2,4′-tricyclo[8.3.0.0^2,6]tridecane]-5,11′-dione hemihydrate}, C₁₇H₂₃NO₄·0.5H₂O, the asymmetric unit contains two molecules of tuberostemoamide with similar conformations and one water molecule. The tuberostemoamide molecule is composed of one seven-membered ring (A) and three five-membered rings (B, C and D). Ring A exists in a chair conformation, both rings B and C exist in envelope conformations, and ring D is almost planar with a mean deviation of 0.0143 (4) Å in one molecule and 0.0095 (3) Å in the other.. The dihedral angles between the planes of rings C and D are 75.1 (3)° in one molecule and 74.5 (3)° for the other. The solvent water molecule links the tuberostemoamide molecules through O—H⋯O(ketone) hydrogen bonds. Weak C—H⋯O interactions are also present, involving both the water molecule and a heterocyclic ether O-atom acceptor.

Related literature

For general background, see: Pilli & Ferreira de Oliveira (2000 ▶); Jiang et al. (2006 ▶). For the biological activity of Stemona alkaloids, see: Xu et al. (2010 ▶); Lin et al. (2008 ▶); Hu et al. (2009 ▶).

Experimental

Crystal data

C₁₇H₂₃NO₄·0.5H₂O
M _r = 314.37
Orthorhombic,
a = 8.6412 (2) Å
b = 10.7998 (2) Å
c = 36.1685 (7) Å
V = 3375.36 (12) Å³
Z = 8
Cu Kα radiation
μ = 0.73 mm⁻¹
T = 298 K
0.42 × 0.30 × 0.27 mm

Data collection

Oxford Diffraction Gemini S Ultra CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.822, T _max = 1.000
8573 measured reflections
4837 independent reflections
4514 reflections with I > 2I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.142
S = 1.06
4837 reflections
412 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.24 e Å⁻³
Absolute structure: Flack (1983 ▶), 1743 Friedel pairs
Flack parameter: −0.1 (2)

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1998 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XP (Bruker, 1998 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811043340/zs2152sup1.cif

e-67-o3056-sup1.cif^{(32.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811043340/zs2152Isup2.hkl

e-67-o3056-Isup2.hkl^{(237KB, 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
O1W—H1WA⋯O1	0.81	1.98	2.796 (3)	175
O1W—H1WB⋯O1′	0.83	1.97	2.784 (3)	171
C5′—H5′A⋯O3ⁱ	0.97	2.58	3.545 (4)	178
C10—H10A⋯O1Wⁱⁱ	0.98	2.58	3.450 (4)	149

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

Acknowledgments

This work was supported by a grant from the New Century Excellent Talents Scheme of the Ministry of Education (grant No. NCET-08–0612), the Guangdong High Level Talent Scheme (to RWJ) and the Fundamental Research Funds for the Central Universities (grant No. 21609202)

supplementary crystallographic information

Comment

The title compound 2(C₁₇H₂₃NO₄) . H₂O (Fig. 1) is a hydrate of tuberostemoamide which has been isolated from the roots of Stemona tuberosa. This plant is a rich source of Stemona alkaloids (Pilli & Ferreira de Oliveira, 2000; Jiang et al., 2006) with anti-tussive activity (Xu et al., 2010). Although the phytochemical properties of tuberostemoamide have been studied Hu et al., 2009); Lin et al., 2008) the crystal structure has not previously been reported. In this study, we report the structure of tuberostemoamide hemihydrate.

The asymmetric unit contains two molecules of tuberostemoamide [(1) and (2)] with similar conformations and one water molecule (Fig. 1). The tuberostemoamide molecule is composed of one seven-membered ring (A) and three five-membered rings (B, C and D). Ring A exists in a chair conformation. Ring B exists in an envelope conformation with C1 displaced by 0.4695 Å from the least-squares plane of the remaining four atoms (C2, C3, N4 and C9A), and the corresponding value for molecule (2) is 0.4868 Å. Ring C also exhibits an envelope conformation with C10 displaced by 0.5930 Å from the least-squares plane of the remaining four atoms (C8, C8, O2 and C11), and the corresponding value for molecule (2) is 0.5886 Å. Ring D is planar with a mean deviation 0.0142 Å for (1) and 0.0101 Å for (2). The dihedral angles between the planes of the rings C and D in molecule (1) is 75.1 (3)° and 74.5 (3)° for molecule (2). The absolute configuration for the compound was not determined with certainty in this analysis.

The water molecule links the tuberostemoamide molecules through O—H···O(ketone) hydrogen bonds (Table 1) with only weak intermolecular C—H···O interactions present, involving both the water molecule and a hetero-ring ether O-acceptor (Fig. 2).

Experimental

The dry ground herbal sample Radix stemonae (8.0 kg) was refluxed with 95% EtOH. After evaporation of the solvent, the crude extract was acidified with 4% HCl and filtered, and the filtrate was washed with diethyl ether (800 ml). The pH of the aqueous layer was raised to 9 with aqueous ammonia (35%) and then extracted with Et₂O (800 ml). The Et₂O layer was evaporated to afford the crude alkaloids (25 g), which was subjected to column chromatography over silica gel, and eluted with cyclohexane-ethyl acetate (10:1 to 0:1) to yield fourteen fractions. Fraction 8 (4 g) was subjected to reverse phase silica gel chromatography to yield seven subfractions, after which the second subfraction (60% CH₃CN, 8 mg) was purified by preparative HPLC eluted by 25% CH₃CN to yield tuberostemoamide (4 mg). The colorless crystals were obtained from a methanol solution at room temperature.