organic compounds
5α-Pregna-1,20-dien-3-one
aHainan Provincial Key Laboratory of Tropical Pharmaceutical Herb Chemistry, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou, Hainan 571158, People's Republic of China, bSchool of Pharmacy, Guangdong Medical College, Dongguan, Guangdong 523808, People's Republic of China, cSchool of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001, People's Republic of China, dCollege of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang, Henan 471022, People's Republic of China, and eKey Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, Ministry of Education, School of Chemistry and Chemical Engineering, Guangxi Normal University, Guilin, Guangxi 541004, People's Republic of China
*Correspondence e-mail: chgying123@163.com
The title compound, C21H30O, was isolated from the soft coral Sinularia sp. The molecule contains four alicyclic rings, all trans-fused, among which three six-membered rings are in different distorted chair conformations while a five-membered ring assumes an envelope form.
Related literature
For general background to marine pregnanes isolated from marine organisms, see: Higgs & Faulkner (1977); Blackman et al. (1985); Hooper & Davies-Coleman (1995); Kittakoop et al. (1999); Li et al. (2009); Yan et al. (2004, 2007); Zhang et al. (2005); Seo et al. (1995).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2004); cell SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536810000863/gk2251sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810000863/gk2251Isup2.hkl
The soft coral Sinularia sp. was collected by SCUBA diving off coral reef at a depth of 15–20 m at Sanya in Hainan Island, PR China, in June 2005. The sample was frozen immediately after collection. The species was identified by Professor Renlin Zou (South China Sea Institute of Oceanology, Chinese Academy of Sciences). The soft coral (800 g, wet weight) was homogenized and extracted with MeOH for three times at room temperature, and the MeOH extracts were combined and then concentrated under vacuo to give a dark brown residue (25.6 g). The residue was partitioned between H2O and EtOAc. The ethyl acetate fraction was subjected to
over silica gel and Sephadex LH-20 to give the pure title compound (54.9 mg). The crystalline compound was obtained through the slow evaporation of the ethyl acetate solution of the title compound.All H atoms were positioned geometrically and treated as riding, with C—H bond lengths constrained to 0.93 Å (CH), 0.97 Å (CH2) 0.96 Å (methyl CH3), and with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl).
Soft corals have been well recognized as marine organisms containing large quantities of α-pregna-1,20-dien-3-one was firstly isolated as a marine natural product from an unknown coral (Higgs et al., 1977), subsequently from a soft coral of the genus Capnella (Blackman et al., 1985; Hooper et al., 1995), Scleronephthya pallida (Kittakoop et al., 1999), Scleronephthya sp. (Yan et al., 2004), Spongodes sp. (Yan et al., 2004; Yan et al., 2007), all of those belong to the family Nephtheidae. Furthermore, the title compound was also reported to be isolated from the family Alcyoniidae from two soft corals Sinularia papillosa (Zhang et al., 2005) and Alcyonium gracillimun(Seo et al., 1995). In course of our investigations of bioactive substances from marine organisms (Li et al., 2009), a soft coral Sinularia sp. which was collected from Sanya, was studied. In this paper, we describe the isolation, structure elucidation and of the title compound.
that exhibit various biological activities. In this regard, 5The molecular structure of the title compound is shown in Fig. 1. The four fused rings are in different distorted conformations. Due to the C1=C2 double bond, ring A is highly distorted with a half-chair conformation. Rings B and C have slightly flattened chair conformations. Ring D assumes an unusual
probably induced by the vinyl substituent. Sstablization of the is due only to weak van der Waals interactions.For general background, see: Higgs & Faulkner (1977); Blackman et al. (1985); Hooper & Davies-Coleman (1995); Kittakoop et al. (1999); Li et al. (2009); Yan et al. (2004, 2007); Zhang et al. (2005); Seo et al. (1995).
Data collection: APEX2 (Bruker, 2004); cell
SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXS97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. View of the title molecular structure with atom numbering scheme and 30% probability displacement ellipsoids for non-hydrogen atoms. |
C21H30O | F(000) = 656 |
Mr = 298.45 | Dx = 1.130 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 7653 reflections |
a = 7.2619 (13) Å | θ = 2.1–26.0° |
b = 10.998 (2) Å | µ = 0.07 mm−1 |
c = 21.964 (4) Å | T = 293 K |
V = 1754.2 (6) Å3 | Block, colorless |
Z = 4 | 0.25 × 0.22 × 0.20 mm |
Bruker APEXII CCD diffractometer | 1995 independent reflections |
Radiation source: fine-focus sealed tube | 1563 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.053 |
Detector resolution: 0 pixels mm-1 | θmax = 26.0°, θmin = 2.1° |
φ and ω scans | h = −8→6 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | k = −13→13 |
Tmin = 0.984, Tmax = 0.987 | l = −27→25 |
7653 measured reflections |
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)] = 0.051 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0531P)2] where P = (Fo2 + 2Fc2)/3 |
1995 reflections | (Δ/σ)max < 0.001 |
201 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
C21H30O | V = 1754.2 (6) Å3 |
Mr = 298.45 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.2619 (13) Å | µ = 0.07 mm−1 |
b = 10.998 (2) Å | T = 293 K |
c = 21.964 (4) Å | 0.25 × 0.22 × 0.20 mm |
Bruker APEXII CCD diffractometer | 1995 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1563 reflections with I > 2σ(I) |
Tmin = 0.984, Tmax = 0.987 | Rint = 0.053 |
7653 measured reflections |
R[F2 > 2σ(F2)] = 0.051 | 0 restraints |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.13 e Å−3 |
1995 reflections | Δρmin = −0.18 e Å−3 |
201 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.4468 (4) | 0.1678 (3) | 0.18505 (11) | 0.0607 (8) | |
H1 | 0.5613 | 0.1344 | 0.1760 | 0.073* | |
C2 | 0.4398 (5) | 0.2554 (3) | 0.22674 (13) | 0.0709 (10) | |
H2 | 0.5495 | 0.2815 | 0.2442 | 0.085* | |
C3 | 0.2683 (5) | 0.3124 (3) | 0.24637 (12) | 0.0684 (9) | |
C4 | 0.0964 (4) | 0.2700 (3) | 0.21577 (12) | 0.0602 (8) | |
H4A | 0.0108 | 0.3375 | 0.2127 | 0.072* | |
H4B | 0.0391 | 0.2075 | 0.2405 | 0.072* | |
C5 | 0.1328 (4) | 0.2193 (2) | 0.15234 (11) | 0.0470 (7) | |
H5 | 0.1822 | 0.2870 | 0.1284 | 0.056* | |
C6 | −0.0413 (4) | 0.1780 (3) | 0.11961 (11) | 0.0507 (7) | |
H6A | −0.1328 | 0.2422 | 0.1210 | 0.061* | |
H6B | −0.0918 | 0.1071 | 0.1399 | 0.061* | |
C7 | 0.0026 (4) | 0.1469 (2) | 0.05360 (11) | 0.0500 (7) | |
H7A | −0.1075 | 0.1149 | 0.0344 | 0.060* | |
H7B | 0.0363 | 0.2210 | 0.0324 | 0.060* | |
C8 | 0.1565 (3) | 0.0555 (2) | 0.04637 (11) | 0.0417 (6) | |
H8 | 0.1119 | −0.0234 | 0.0610 | 0.050* | |
C9 | 0.3289 (3) | 0.0902 (2) | 0.08406 (11) | 0.0414 (6) | |
H9 | 0.3736 | 0.1667 | 0.0666 | 0.050* | |
C10 | 0.2826 (4) | 0.1193 (2) | 0.15166 (11) | 0.0446 (6) | |
C11 | 0.4847 (4) | −0.0019 (2) | 0.07458 (11) | 0.0500 (7) | |
H11A | 0.4480 | −0.0796 | 0.0916 | 0.060* | |
H11B | 0.5932 | 0.0255 | 0.0964 | 0.060* | |
C12 | 0.5332 (4) | −0.0188 (2) | 0.00707 (11) | 0.0477 (7) | |
H12A | 0.5836 | 0.0564 | −0.0089 | 0.057* | |
H12B | 0.6266 | −0.0814 | 0.0032 | 0.057* | |
C13 | 0.3649 (3) | −0.0546 (2) | −0.02996 (11) | 0.0430 (6) | |
C14 | 0.2141 (3) | 0.0410 (2) | −0.01977 (11) | 0.0429 (6) | |
H14 | 0.2689 | 0.1190 | −0.0315 | 0.051* | |
C15 | 0.0723 (4) | 0.0120 (3) | −0.06889 (11) | 0.0591 (8) | |
H15A | 0.0036 | 0.0842 | −0.0802 | 0.071* | |
H15B | −0.0133 | −0.0498 | −0.0551 | 0.071* | |
C16 | 0.1885 (4) | −0.0347 (3) | −0.12272 (13) | 0.0706 (9) | |
H16A | 0.1441 | −0.1135 | −0.1360 | 0.085* | |
H16B | 0.1811 | 0.0215 | −0.1567 | 0.085* | |
C17 | 0.3882 (4) | −0.0446 (3) | −0.09989 (11) | 0.0528 (7) | |
H17 | 0.4484 | 0.0334 | −0.1083 | 0.063* | |
C18 | 0.3017 (4) | −0.1838 (2) | −0.01350 (13) | 0.0591 (8) | |
H18A | 0.4009 | −0.2398 | −0.0204 | 0.089* | |
H18B | 0.1985 | −0.2059 | −0.0384 | 0.089* | |
H18C | 0.2664 | −0.1863 | 0.0286 | 0.089* | |
C19 | 0.2221 (5) | 0.0030 (3) | 0.18588 (12) | 0.0617 (9) | |
H19A | 0.3250 | −0.0512 | 0.1895 | 0.093* | |
H19B | 0.1252 | −0.0363 | 0.1636 | 0.093* | |
H19C | 0.1785 | 0.0245 | 0.2257 | 0.093* | |
C20 | 0.5016 (5) | −0.1414 (3) | −0.12920 (12) | 0.0672 (9) | |
H20 | 0.4512 | −0.2189 | −0.1317 | 0.081* | |
C21 | 0.6668 (5) | −0.1253 (4) | −0.15167 (14) | 0.0843 (12) | |
H21A | 0.7218 | −0.0490 | −0.1500 | 0.101* | |
H21B | 0.7292 | −0.1903 | −0.1693 | 0.101* | |
O1 | 0.2658 (4) | 0.3879 (3) | 0.28688 (11) | 0.1084 (10) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.052 (2) | 0.083 (2) | 0.0466 (16) | −0.0024 (18) | −0.0062 (13) | −0.0025 (15) |
C2 | 0.061 (2) | 0.096 (3) | 0.0553 (18) | −0.013 (2) | −0.0124 (15) | −0.0138 (18) |
C3 | 0.079 (2) | 0.080 (2) | 0.0458 (16) | −0.006 (2) | −0.0011 (16) | −0.0092 (16) |
C4 | 0.064 (2) | 0.069 (2) | 0.0477 (17) | 0.0012 (17) | 0.0080 (15) | −0.0002 (14) |
C5 | 0.0485 (17) | 0.0497 (16) | 0.0428 (14) | −0.0039 (14) | 0.0042 (12) | 0.0054 (11) |
C6 | 0.0385 (16) | 0.0609 (17) | 0.0528 (15) | 0.0040 (15) | 0.0040 (12) | 0.0011 (13) |
C7 | 0.0376 (15) | 0.0606 (17) | 0.0519 (15) | 0.0020 (15) | −0.0075 (12) | 0.0021 (12) |
C8 | 0.0352 (15) | 0.0439 (15) | 0.0461 (14) | −0.0050 (13) | −0.0032 (11) | 0.0046 (11) |
C9 | 0.0386 (15) | 0.0432 (15) | 0.0425 (13) | −0.0045 (13) | −0.0013 (11) | 0.0055 (11) |
C10 | 0.0430 (16) | 0.0523 (15) | 0.0386 (13) | −0.0017 (14) | −0.0032 (12) | 0.0046 (11) |
C11 | 0.0402 (16) | 0.0606 (18) | 0.0493 (15) | 0.0031 (14) | −0.0084 (12) | −0.0012 (13) |
C12 | 0.0408 (17) | 0.0443 (15) | 0.0580 (16) | 0.0010 (13) | −0.0012 (12) | −0.0028 (12) |
C13 | 0.0400 (16) | 0.0423 (15) | 0.0468 (15) | −0.0025 (13) | −0.0002 (12) | 0.0019 (11) |
C14 | 0.0392 (15) | 0.0463 (15) | 0.0432 (14) | −0.0017 (13) | −0.0053 (12) | 0.0050 (11) |
C15 | 0.0547 (18) | 0.074 (2) | 0.0490 (17) | 0.0044 (17) | −0.0140 (14) | −0.0022 (14) |
C16 | 0.072 (2) | 0.092 (2) | 0.0473 (16) | 0.003 (2) | −0.0123 (16) | −0.0092 (16) |
C17 | 0.0557 (19) | 0.0532 (17) | 0.0494 (16) | −0.0035 (16) | 0.0026 (13) | −0.0025 (13) |
C18 | 0.061 (2) | 0.0501 (17) | 0.0664 (17) | −0.0050 (16) | −0.0004 (15) | 0.0007 (14) |
C19 | 0.071 (2) | 0.0659 (19) | 0.0482 (16) | 0.0009 (18) | 0.0012 (14) | 0.0170 (13) |
C20 | 0.075 (2) | 0.077 (2) | 0.0502 (17) | 0.000 (2) | 0.0013 (16) | −0.0143 (15) |
C21 | 0.071 (3) | 0.108 (3) | 0.074 (2) | 0.013 (2) | 0.009 (2) | −0.027 (2) |
O1 | 0.114 (2) | 0.125 (2) | 0.0864 (17) | 0.003 (2) | −0.0065 (16) | −0.0523 (16) |
C1—C2 | 1.330 (4) | C11—H11B | 0.9700 |
C1—C10 | 1.498 (4) | C12—C13 | 1.520 (3) |
C1—H1 | 0.9300 | C12—H12A | 0.9700 |
C2—C3 | 1.460 (5) | C12—H12B | 0.9700 |
C2—H2 | 0.9300 | C13—C18 | 1.536 (4) |
C3—O1 | 1.217 (3) | C13—C14 | 1.534 (4) |
C3—C4 | 1.493 (4) | C13—C17 | 1.549 (3) |
C4—C5 | 1.524 (4) | C14—C15 | 1.525 (3) |
C4—H4A | 0.9700 | C14—H14 | 0.9800 |
C4—H4B | 0.9700 | C15—C16 | 1.541 (4) |
C5—C6 | 1.523 (4) | C15—H15A | 0.9700 |
C5—C10 | 1.547 (4) | C15—H15B | 0.9700 |
C5—H5 | 0.9800 | C16—C17 | 1.539 (4) |
C6—C7 | 1.523 (4) | C16—H16A | 0.9700 |
C6—H6A | 0.9700 | C16—H16B | 0.9700 |
C6—H6B | 0.9700 | C17—C20 | 1.492 (4) |
C7—C8 | 1.512 (3) | C17—H17 | 0.9800 |
C7—H7A | 0.9700 | C18—H18A | 0.9600 |
C7—H7B | 0.9700 | C18—H18B | 0.9600 |
C8—C14 | 1.520 (3) | C18—H18C | 0.9600 |
C8—C9 | 1.549 (3) | C19—H19A | 0.9600 |
C8—H8 | 0.9800 | C19—H19B | 0.9600 |
C9—C11 | 1.532 (3) | C19—H19C | 0.9600 |
C9—C10 | 1.556 (3) | C20—C21 | 1.309 (4) |
C9—H9 | 0.9800 | C20—H20 | 0.9300 |
C10—C19 | 1.547 (4) | C21—H21A | 0.9300 |
C11—C12 | 1.535 (4) | C21—H21B | 0.9300 |
C11—H11A | 0.9700 | ||
C2—C1—C10 | 124.4 (3) | H11A—C11—H11B | 107.9 |
C2—C1—H1 | 117.8 | C13—C12—C11 | 111.3 (2) |
C10—C1—H1 | 117.8 | C13—C12—H12A | 109.4 |
C1—C2—C3 | 123.2 (3) | C11—C12—H12A | 109.4 |
C1—C2—H2 | 118.4 | C13—C12—H12B | 109.4 |
C3—C2—H2 | 118.4 | C11—C12—H12B | 109.4 |
O1—C3—C2 | 121.5 (3) | H12A—C12—H12B | 108.0 |
O1—C3—C4 | 122.0 (3) | C12—C13—C18 | 110.7 (2) |
C2—C3—C4 | 116.5 (2) | C12—C13—C14 | 108.6 (2) |
C3—C4—C5 | 112.4 (2) | C18—C13—C14 | 112.7 (2) |
C3—C4—H4A | 109.1 | C12—C13—C17 | 115.1 (2) |
C5—C4—H4A | 109.1 | C18—C13—C17 | 109.4 (2) |
C3—C4—H4B | 109.1 | C14—C13—C17 | 100.0 (2) |
C5—C4—H4B | 109.1 | C8—C14—C15 | 120.8 (2) |
H4A—C4—H4B | 107.9 | C8—C14—C13 | 114.1 (2) |
C6—C5—C4 | 113.4 (2) | C15—C14—C13 | 103.6 (2) |
C6—C5—C10 | 111.5 (2) | C8—C14—H14 | 105.7 |
C4—C5—C10 | 113.0 (2) | C15—C14—H14 | 105.7 |
C6—C5—H5 | 106.1 | C13—C14—H14 | 105.7 |
C4—C5—H5 | 106.1 | C14—C15—C16 | 104.1 (2) |
C10—C5—H5 | 106.1 | C14—C15—H15A | 110.9 |
C5—C6—C7 | 110.0 (2) | C16—C15—H15A | 110.9 |
C5—C6—H6A | 109.7 | C14—C15—H15B | 110.9 |
C7—C6—H6A | 109.7 | C16—C15—H15B | 110.9 |
C5—C6—H6B | 109.7 | H15A—C15—H15B | 109.0 |
C7—C6—H6B | 109.7 | C17—C16—C15 | 106.8 (2) |
H6A—C6—H6B | 108.2 | C17—C16—H16A | 110.4 |
C8—C7—C6 | 113.8 (2) | C15—C16—H16A | 110.4 |
C8—C7—H7A | 108.8 | C17—C16—H16B | 110.4 |
C6—C7—H7A | 108.8 | C15—C16—H16B | 110.4 |
C8—C7—H7B | 108.8 | H16A—C16—H16B | 108.6 |
C6—C7—H7B | 108.8 | C20—C17—C16 | 115.5 (3) |
H7A—C7—H7B | 107.7 | C20—C17—C13 | 116.0 (2) |
C7—C8—C14 | 111.9 (2) | C16—C17—C13 | 103.0 (2) |
C7—C8—C9 | 112.2 (2) | C20—C17—H17 | 107.3 |
C14—C8—C9 | 108.3 (2) | C16—C17—H17 | 107.3 |
C7—C8—H8 | 108.1 | C13—C17—H17 | 107.3 |
C14—C8—H8 | 108.1 | C13—C18—H18A | 109.5 |
C9—C8—H8 | 108.1 | C13—C18—H18B | 109.5 |
C11—C9—C8 | 111.2 (2) | H18A—C18—H18B | 109.5 |
C11—C9—C10 | 115.2 (2) | C13—C18—H18C | 109.5 |
C8—C9—C10 | 112.7 (2) | H18A—C18—H18C | 109.5 |
C11—C9—H9 | 105.6 | H18B—C18—H18C | 109.5 |
C8—C9—H9 | 105.6 | C10—C19—H19A | 109.5 |
C10—C9—H9 | 105.6 | C10—C19—H19B | 109.5 |
C1—C10—C19 | 106.4 (2) | H19A—C19—H19B | 109.5 |
C1—C10—C5 | 107.6 (2) | C10—C19—H19C | 109.5 |
C19—C10—C5 | 112.5 (2) | H19A—C19—H19C | 109.5 |
C1—C10—C9 | 111.6 (2) | H19B—C19—H19C | 109.5 |
C19—C10—C9 | 110.8 (2) | C21—C20—C17 | 124.9 (3) |
C5—C10—C9 | 107.9 (2) | C21—C20—H20 | 117.5 |
C9—C11—C12 | 112.4 (2) | C17—C20—H20 | 117.5 |
C9—C11—H11A | 109.1 | C20—C21—H21A | 120.0 |
C12—C11—H11A | 109.1 | C20—C21—H21B | 120.0 |
C9—C11—H11B | 109.1 | H21A—C21—H21B | 120.0 |
C12—C11—H11B | 109.1 |
Experimental details
Crystal data | |
Chemical formula | C21H30O |
Mr | 298.45 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 7.2619 (13), 10.998 (2), 21.964 (4) |
V (Å3) | 1754.2 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.25 × 0.22 × 0.20 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.984, 0.987 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7653, 1995, 1563 |
Rint | 0.053 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.051, 0.114, 1.10 |
No. of reflections | 1995 |
No. of parameters | 201 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.18 |
Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2006), SHELXTL (Sheldrick, 2008).
Acknowledgements
The authors acknowledge financial support from the National Natural Science Foundation of China (grant No. 20862005), the Program for New Century Excellent Talents in Universities (grant No. NCET-08-0656), the Youthful Fund of Guangdong Medical College (grant No. XQ0511) and the Open Research Fund Program of the Key Laboratory of Marine Drugs (Ocean University of China), the Ministry of Education [grant No. KLMD (OUC) 200801].
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Soft corals have been well recognized as marine organisms containing large quantities of secondary metabolites that exhibit various biological activities. In this regard, 5α-pregna-1,20-dien-3-one was firstly isolated as a marine natural product from an unknown coral (Higgs et al., 1977), subsequently from a soft coral of the genus Capnella (Blackman et al., 1985; Hooper et al., 1995), Scleronephthya pallida (Kittakoop et al., 1999), Scleronephthya sp. (Yan et al., 2004), Spongodes sp. (Yan et al., 2004; Yan et al., 2007), all of those belong to the family Nephtheidae. Furthermore, the title compound was also reported to be isolated from the family Alcyoniidae from two soft corals Sinularia papillosa (Zhang et al., 2005) and Alcyonium gracillimun(Seo et al., 1995). In course of our investigations of bioactive substances from marine organisms (Li et al., 2009), a soft coral Sinularia sp. which was collected from Sanya, was studied. In this paper, we describe the isolation, structure elucidation and crystal structure of the title compound.
The molecular structure of the title compound is shown in Fig. 1. The four fused rings are in different distorted conformations. Due to the C1=C2 double bond, ring A is highly distorted with a half-chair conformation. Rings B and C have slightly flattened chair conformations. Ring D assumes an unusual envelope conformation, probably induced by the vinyl substituent. Sstablization of the crystal structure is due only to weak van der Waals interactions.