5α-Pregna-1,20-dien-3-one.

The title compound, C(21)H(30)O, was isolated from the soft coral Sinularia sp. The mol-ecule 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

C21H30O

M = 298.45

Orthorhombic,

a = 7.2619 (13) Å

b = 10.998 (2) Å

c = 21.964 (4) Å

V = 1754.2 (6) Å3

Z = 4

Mo Kα radiation

μ = 0.07 mm−1

T = 293 K

0.25 × 0.22 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T min = 0.984, T max = 0.987

7653 measured reflections

1995 independent reflections

1563 reflections with I > 2σ(I)

R int = 0.053

Refinement

R[F 2 > 2σ(F 2)] = 0.051

wR(F 2) = 0.114

S = 1.10

1995 reflections

201 parameters

H-atom parameters constrained

Δρmax = 0.13 e Å−3

Δρmin = −0.18 e Å−3

Data collection: APEX2 (Bruker, 2004 ▶); cell refinement: 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.

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810000863/gk2251sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810000863/gk2251Isup2.hkl

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

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	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 = −0.17 e Å−3

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