Ethyl (1R,4S,5R,9S,10R,13S)-5,9,13-trimethyl-14-methyl­ene-14-oxotetra­cyclo­[11.2.1.01,10.04,9]hexa­decane-5-carboxyl­ate

Hao Shi

doi:10.1107/S1600536809053380

. 2009 Dec 16;66(Pt 1):o154. doi: 10.1107/S1600536809053380

Ethyl (1R,4S,5R,9S,10R,13S)-5,9,13-trimethyl-14-methylene-14-oxotetracyclo[11.2.1.0^1,10.0^4,9]hexadecane-5-carboxylate

Hao Shi ^a,^*

PMCID: PMC2980194 PMID: 21580043

Abstract

The title compound, C₂₂H₃₄O₃, was synthesized from isosteviol. The asymmetric unit contains of two independent molecules with the same absolute configurations. In both the molecules, the three six-membered rings adopt chair conformations, the stereochemistry of the A/B and B/C ring junctions are trans, and the five-membered ring D adopts an envelope conformation.

Related literature

Since the title compound was prepared from isosteviol, the configuration can be deduced from the known chirality of the isosteviol, see: Rodrigues & Lechat (1988 ▶), Xue et al. (1993 ▶). For the pharmacological activity of isosteviol, see: Liu et al. (2001 ▶); Mizushina et al. (2005 ▶); Wong et al. (2004 ▶); Zhang & Xu (2004 ▶). For ring conformations, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C₂₂H₃₄O₃
M _r = 346.49
Triclinic,
a = 6.5365 (9) Å
b = 12.5639 (15) Å
c = 13.1212 (16) Å
α = 69.174 (1)°
β = 87.518 (2)°
γ = 79.018 (1)°
V = 988.4 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.49 × 0.42 × 0.15 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1999 ▶) T _min = 0.964, T _max = 0.989
5226 measured reflections
3451 independent reflections
1824 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.067
wR(F ²) = 0.189
S = 0.90
3451 reflections
459 parameters
3 restraints
H-atom parameters constrained
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: SMART (Bruker, 1999 ▶); cell refinement: SAINT (Bruker, 1999 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97 nd PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809053380/dn2514sup1.cif

e-66-0o154-sup1.cif^{(35.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809053380/dn2514Isup2.hkl

e-66-0o154-Isup2.hkl^{(169.2KB, hkl)}

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

Table 1. Comparison of the puckering parameters (Å, °) for the six and five-membered rings in molecules 1 and 2.

Molecule		1			2
Puckering parameters	Q	θ	ϕ	Q	θ	ϕ
Ring A1, A2	0.536 (7)	180.0 (7)	273 (27)	0.545 (8)	177.2 (8)	251 (29)
Ring B1, B2	0.557 (7)	9.5 (7)	72 (4)	0.561 (7)	7.8 (7)	71 (5)
Ring C1, C2	0.633 (7)	164.8 (6)	120 (3)	0.646 (8)	163.2 (7)	131 (2)
Puckering parameters		q₂	ϕ₂		q₂	ϕ₂
Ring D1, D2		0.467 (8)	333.7 (10)		0.452 (8)	332.2 (11)

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Ring A1 atoms C2–C7, A2 C24–C29, B1 C6–C11, B2 C28–C33, C1 C10–C14/C17, C2 C32–C36/C39, D1 C14–C16/C10/C17 and D2 C36–C38/C32/C39.

Acknowledgments

This material is based upon work funded by the Zhejiang Provincial Natural Science Foundation of China under grant No. Y2090552 and the Open Foundation of Key Disciplines within the Zhejiang Provincial Key Disciplines.

supplementary crystallographic information

Comment

Since the natural diterpenoid isosteviol has good pharmacological activity against a number of significant diseases including ischemia–reperfusion injury, hypertension, and cancer (Liu, et al., 2001; Mizushina et al., 2005; Wong et al., 2004; Zhang & Xu, 2004), the title compound was derived from it. Two independent molecules with identical absolute configuration are present in the asymmetric unit . Both molecule 1 (Fig.1) and molecule 2 (Fig.2) are built up from three six-membered rings and one five-membered ring. Some geometrical features (puckering parameters, Cremer & Pople, 1975) of these rings were investigated (Table 1) using PLATON (Spek, 2009).

Since the title compound was prepared from isosteviol, the configuration can be deduced from the known chirality of the isosteviol (Rodrigues & Lechat, 1988; Xue et al., 1993), and thus Fig. 1 and Fig. 2 represents the correct absolute configuration.

Experimental

A mixture of isosteviol (1 mmol), K₂CO₃ (2 mmol) and 10 mL of DMSO was transferred into a flask connected with refluxing equipment. After stirring for 5 min, bromoethane (1.2 mmol) was added, then stirring at 40°C for 6 h, the reaction mixture was poured into 40 mL water, extracted with 3×30 mL e thyl acetate, the ethyl acetate layer was washed with 3×30 mL water, then dryed with anhydrous Na₂SO₄, purified with silion colum and the title compound was gained. Crystals suitable for X-ray structure analysis were obtained by slow evaporation from a solution of isopropyl alcohol at room temperature.