organic compounds
14,15-Didehydrohellebrigenin
aGuangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, Institute of Traditional Chinese Medicine and Natural Products, Jinan University, Guangzhou 510632, People's Republic of China
*Correspondence e-mail: trwjiang@jnu.edu.cn
The title compound, C24H30O5, is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihydroxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclohexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclohexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O—H⋯O hydrogen bond in the molecule involving the hydroxy groups. In the crystal, O—H⋯O hydrogen bonds link the molecules into chains propagating along [010]. The chains are linked by C—H⋯O contacts into a three-dimensional network.
Related literature
For previous isolations of hellebrigenin, see: Urscheler et al. (1955); Yang et al. (2010); Zhao et al. (2010). For its inhibitory activity against adenosinetriphosphatase of the 3-acetate, 3,5-diacetate, 3-iodoacetate and 3-bromoacetate of hellebrigenin, see: Ruoho et al. (1968). For the treatment of hellebrigenin with sodium hydroxide, see: Kupchan et al. (1969). For the stereochemistry of bufalin and secohellebrigeninamide, see: Rohrer et al. (1982); Yuan et al. (2012).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Agilent, 2011); cell CrysAlis PRO; data reduction: XPREP (Sheldrick, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536812018570/su2412sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536812018570/su2412Isup2.hkl
Hellebrigenin (104.32 mg) was dissolved in a mixture of dichloromethane (2 ml) and methanol (3 ml). Hydrochloric acid (36%, 10 ml) was added. The solution was stirred for three hours at room temperature. Then the mixture was then poured into cold water and extracted with ethyl acetate. The organic phase was washed twice with water and concentrated under reduced pressure. The residue was subjected to preparative HPLC to afford the title compound (41 mg). The compound was recrystallized in methanol at room temperature to afford colourless prism-like crystals.
The C-bound H-atoms were included in calculated positions and treated as riding atoms: O-H = 0.82 Å, C-H = 0.98, 0.96, 0.97 and 0.93 Å for CH, CH3, CH2 and CH(aryl) H-atoms, respectively, with Uiso(H) = k × Ueq(O,C), where k = 1.5 for OH and CH3 H-atoms and = 1.2 for other H-atoms. The
of the title compound could not be determined crystallographically; the refined to -0.1 (3). It was assigned with reference to the known configuration of the closely related compounds bufalin (Rohrer et al., 1982) and secohellebrigeninamide (Yuan et al., 2012).Data collection: CrysAlis PRO (Agilent, 2011); cell
CrysAlis PRO (Agilent, 2011); data reduction: XPREP (Sheldrick, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C24H30O5 | F(000) = 428 |
Mr = 398.48 | Dx = 1.276 Mg m−3 |
Monoclinic, P21 | Cu Kα radiation, λ = 1.54184 Å |
a = 10.7628 (4) Å | Cell parameters from 1435 reflections |
b = 6.6016 (2) Å | θ = 3.0–62.5° |
c = 14.6376 (5) Å | µ = 0.71 mm−1 |
β = 94.224 (3)° | T = 291 K |
V = 1037.20 (6) Å3 | Prism, colourless |
Z = 2 | 0.40 × 0.26 × 0.23 mm |
Oxford Gemini S Ultra Sapphire CCD diffractometer | 2238 independent reflections |
Radiation source: fine-focus sealed tube | 2042 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
ω scan | θmax = 62.6°, θmin = 3.0° |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | h = −6→12 |
Tmin = 0.819, Tmax = 1.000 | k = −7→4 |
3100 measured reflections | l = −16→16 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.042 | H-atom parameters constrained |
wR(F2) = 0.115 | w = 1/[σ2(Fo2) + (0.0726P)2 + 0.1057P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
2238 reflections | Δρmax = 0.24 e Å−3 |
266 parameters | Δρmin = −0.20 e Å−3 |
1 restraint | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0045 (12) |
C24H30O5 | V = 1037.20 (6) Å3 |
Mr = 398.48 | Z = 2 |
Monoclinic, P21 | Cu Kα radiation |
a = 10.7628 (4) Å | µ = 0.71 mm−1 |
b = 6.6016 (2) Å | T = 291 K |
c = 14.6376 (5) Å | 0.40 × 0.26 × 0.23 mm |
β = 94.224 (3)° |
Oxford Gemini S Ultra Sapphire CCD diffractometer | 2238 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | 2042 reflections with I > 2σ(I) |
Tmin = 0.819, Tmax = 1.000 | Rint = 0.023 |
3100 measured reflections |
R[F2 > 2σ(F2)] = 0.042 | 1 restraint |
wR(F2) = 0.115 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.24 e Å−3 |
2238 reflections | Δρmin = −0.20 e Å−3 |
266 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles |
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 | ||
O1 | 0.40415 (18) | 0.7669 (4) | 1.06950 (14) | 0.0564 (7) | |
O2 | 0.3968 (2) | 0.9967 (4) | 0.91061 (15) | 0.0605 (8) | |
O3 | 0.1076 (3) | 1.2425 (4) | 0.8935 (2) | 0.0882 (11) | |
O4 | −0.6574 (2) | 0.2486 (7) | 0.5959 (2) | 0.0998 (13) | |
O5 | −0.4844 (3) | 0.2651 (7) | 0.69025 (19) | 0.1009 (13) | |
C1 | 0.1594 (2) | 0.8911 (5) | 0.98577 (16) | 0.0395 (8) | |
C2 | 0.1910 (3) | 0.6866 (5) | 1.02785 (18) | 0.0438 (9) | |
C3 | 0.3250 (3) | 0.6280 (5) | 1.01530 (18) | 0.0478 (9) | |
C4 | 0.3517 (3) | 0.6385 (5) | 0.91490 (19) | 0.0475 (9) | |
C5 | 0.3174 (2) | 0.8405 (5) | 0.86880 (19) | 0.0451 (9) | |
C6 | 0.3428 (3) | 0.8346 (7) | 0.7677 (2) | 0.0609 (13) | |
C7 | 0.2526 (3) | 0.6979 (6) | 0.71152 (19) | 0.0552 (10) | |
C8 | 0.1166 (2) | 0.7489 (5) | 0.72275 (17) | 0.0435 (9) | |
C9 | 0.0893 (2) | 0.7573 (5) | 0.82503 (16) | 0.0358 (8) | |
C10 | 0.1798 (2) | 0.9001 (4) | 0.88277 (16) | 0.0376 (8) | |
C11 | −0.0483 (2) | 0.8023 (5) | 0.83501 (19) | 0.0438 (9) | |
C12 | −0.1299 (2) | 0.6349 (5) | 0.79095 (17) | 0.0427 (9) | |
C13 | −0.1110 (2) | 0.6065 (5) | 0.68901 (16) | 0.0390 (8) | |
C14 | 0.0279 (2) | 0.6028 (5) | 0.67349 (16) | 0.0414 (8) | |
C15 | 0.0524 (3) | 0.4602 (6) | 0.61287 (19) | 0.0544 (10) | |
C16 | −0.0631 (3) | 0.3465 (6) | 0.5790 (2) | 0.0597 (10) | |
C17 | −0.1499 (3) | 0.3905 (5) | 0.65465 (18) | 0.0439 (9) | |
C18 | −0.1773 (3) | 0.7733 (6) | 0.6318 (2) | 0.0599 (11) | |
C19 | 0.1572 (3) | 1.1166 (5) | 0.8511 (2) | 0.0560 (11) | |
C20 | −0.2876 (3) | 0.3558 (5) | 0.63458 (18) | 0.0459 (9) | |
C21 | −0.3594 (3) | 0.3021 (8) | 0.7029 (2) | 0.0707 (13) | |
C22 | −0.3499 (3) | 0.3797 (7) | 0.5489 (2) | 0.0683 (13) | |
C23 | −0.4722 (3) | 0.3462 (7) | 0.5348 (2) | 0.0660 (13) | |
C24 | −0.5468 (3) | 0.2853 (7) | 0.6046 (3) | 0.0716 (13) | |
H1 | 0.47040 | 0.71120 | 1.08520 | 0.0850* | |
H1A | 0.21060 | 0.99380 | 1.01750 | 0.0470* | |
H1B | 0.07300 | 0.92230 | 0.99440 | 0.0470* | |
H2 | 0.40780 | 0.97540 | 0.96580 | 0.0910* | |
H2A | 0.13570 | 0.58490 | 0.99960 | 0.0530* | |
H2B | 0.17820 | 0.69050 | 1.09270 | 0.0530* | |
H3 | 0.34000 | 0.48970 | 1.03780 | 0.0570* | |
H4A | 0.30580 | 0.53130 | 0.88210 | 0.0570* | |
H4B | 0.43970 | 0.61350 | 0.90990 | 0.0570* | |
H6A | 0.33670 | 0.97090 | 0.74300 | 0.0730* | |
H6B | 0.42710 | 0.78710 | 0.76200 | 0.0730* | |
H7A | 0.26790 | 0.55840 | 0.72980 | 0.0660* | |
H7B | 0.26840 | 0.70970 | 0.64730 | 0.0660* | |
H8 | 0.10020 | 0.88370 | 0.69650 | 0.0520* | |
H9 | 0.10440 | 0.62050 | 0.84930 | 0.0430* | |
H11A | −0.06290 | 0.81300 | 0.89940 | 0.0530* | |
H11B | −0.07020 | 0.93080 | 0.80600 | 0.0530* | |
H12A | −0.21660 | 0.66700 | 0.79790 | 0.0510* | |
H12B | −0.11100 | 0.50860 | 0.82290 | 0.0510* | |
H15 | 0.13140 | 0.43410 | 0.59380 | 0.0650* | |
H16A | −0.04700 | 0.20260 | 0.57370 | 0.0720* | |
H16B | −0.09700 | 0.39790 | 0.52020 | 0.0720* | |
H17 | −0.12410 | 0.29820 | 0.70490 | 0.0530* | |
H18A | −0.26480 | 0.76990 | 0.64050 | 0.0900* | |
H18B | −0.16490 | 0.75220 | 0.56830 | 0.0900* | |
H18C | −0.14390 | 0.90280 | 0.65080 | 0.0900* | |
H19 | 0.18410 | 1.15340 | 0.79450 | 0.0670* | |
H21 | −0.32140 | 0.28980 | 0.76170 | 0.0850* | |
H22 | −0.30540 | 0.42010 | 0.49990 | 0.0820* | |
H23 | −0.50960 | 0.36410 | 0.47610 | 0.0790* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0446 (11) | 0.0602 (15) | 0.0613 (12) | 0.0074 (11) | −0.0164 (9) | −0.0076 (12) |
O2 | 0.0543 (12) | 0.0632 (16) | 0.0627 (12) | −0.0261 (12) | −0.0045 (10) | −0.0051 (12) |
O3 | 0.116 (2) | 0.0359 (15) | 0.112 (2) | 0.0128 (16) | 0.0031 (17) | 0.0009 (16) |
O4 | 0.0522 (14) | 0.124 (3) | 0.120 (2) | −0.0018 (18) | −0.0148 (14) | −0.038 (2) |
O5 | 0.0697 (16) | 0.150 (3) | 0.0816 (17) | −0.025 (2) | −0.0037 (13) | 0.007 (2) |
C1 | 0.0372 (13) | 0.0389 (16) | 0.0414 (13) | −0.0009 (12) | −0.0037 (10) | −0.0075 (13) |
C2 | 0.0453 (15) | 0.0443 (18) | 0.0412 (13) | −0.0040 (13) | −0.0007 (11) | 0.0019 (13) |
C3 | 0.0476 (15) | 0.0405 (18) | 0.0535 (15) | 0.0029 (14) | −0.0081 (12) | −0.0001 (14) |
C4 | 0.0372 (14) | 0.0475 (19) | 0.0573 (15) | 0.0057 (13) | 0.0012 (11) | −0.0085 (15) |
C5 | 0.0384 (14) | 0.0475 (19) | 0.0486 (14) | −0.0148 (14) | −0.0012 (11) | −0.0030 (14) |
C6 | 0.0495 (16) | 0.080 (3) | 0.0543 (16) | −0.0202 (18) | 0.0106 (13) | 0.0022 (18) |
C7 | 0.0486 (16) | 0.075 (2) | 0.0433 (14) | −0.0173 (16) | 0.0113 (11) | −0.0056 (16) |
C8 | 0.0496 (15) | 0.0422 (18) | 0.0382 (13) | −0.0053 (14) | 0.0008 (11) | 0.0031 (13) |
C9 | 0.0392 (13) | 0.0307 (15) | 0.0370 (12) | −0.0043 (12) | −0.0011 (9) | −0.0034 (12) |
C10 | 0.0413 (13) | 0.0304 (15) | 0.0404 (13) | −0.0012 (12) | −0.0026 (10) | −0.0007 (12) |
C11 | 0.0411 (14) | 0.0432 (18) | 0.0458 (14) | 0.0023 (13) | −0.0048 (11) | −0.0111 (13) |
C12 | 0.0375 (13) | 0.0494 (18) | 0.0408 (13) | −0.0058 (13) | 0.0007 (10) | −0.0094 (14) |
C13 | 0.0458 (14) | 0.0342 (16) | 0.0361 (12) | −0.0023 (13) | −0.0039 (10) | −0.0006 (12) |
C14 | 0.0467 (14) | 0.0467 (18) | 0.0306 (11) | −0.0092 (14) | 0.0020 (10) | 0.0004 (13) |
C15 | 0.0555 (17) | 0.061 (2) | 0.0475 (15) | −0.0072 (17) | 0.0087 (12) | −0.0118 (17) |
C16 | 0.0653 (18) | 0.062 (2) | 0.0520 (15) | −0.0126 (18) | 0.0053 (14) | −0.0218 (16) |
C17 | 0.0509 (15) | 0.0412 (17) | 0.0388 (12) | −0.0044 (14) | −0.0010 (11) | −0.0025 (13) |
C18 | 0.069 (2) | 0.0444 (19) | 0.0628 (18) | −0.0022 (17) | −0.0196 (14) | 0.0090 (17) |
C19 | 0.069 (2) | 0.0352 (18) | 0.0610 (17) | −0.0103 (17) | −0.0131 (15) | 0.0044 (16) |
C20 | 0.0526 (15) | 0.0406 (17) | 0.0431 (13) | −0.0074 (15) | −0.0064 (12) | −0.0031 (14) |
C21 | 0.0501 (17) | 0.106 (3) | 0.0540 (17) | −0.021 (2) | −0.0095 (13) | 0.010 (2) |
C22 | 0.072 (2) | 0.082 (3) | 0.0487 (16) | −0.021 (2) | −0.0097 (15) | 0.0023 (19) |
C23 | 0.0618 (19) | 0.079 (3) | 0.0527 (16) | −0.0093 (19) | −0.0253 (15) | −0.0017 (18) |
C24 | 0.0517 (18) | 0.079 (3) | 0.081 (2) | 0.002 (2) | −0.0169 (16) | −0.020 (2) |
O1—C3 | 1.448 (4) | C20—C22 | 1.387 (4) |
O2—C5 | 1.446 (4) | C22—C23 | 1.336 (5) |
O3—C19 | 1.187 (4) | C23—C24 | 1.404 (5) |
O4—C24 | 1.212 (4) | C1—H1A | 0.9700 |
O5—C21 | 1.367 (5) | C1—H1B | 0.9700 |
O5—C24 | 1.384 (5) | C2—H2A | 0.9700 |
O1—H1 | 0.8200 | C2—H2B | 0.9700 |
O2—H2 | 0.8200 | C3—H3 | 0.9800 |
C1—C10 | 1.541 (3) | C4—H4A | 0.9700 |
C1—C2 | 1.512 (4) | C4—H4B | 0.9700 |
C2—C3 | 1.517 (5) | C6—H6A | 0.9700 |
C3—C4 | 1.520 (4) | C6—H6B | 0.9700 |
C4—C5 | 1.528 (5) | C7—H7A | 0.9700 |
C5—C10 | 1.560 (3) | C7—H7B | 0.9700 |
C5—C6 | 1.525 (4) | C8—H8 | 0.9800 |
C6—C7 | 1.522 (5) | C9—H9 | 0.9800 |
C7—C8 | 1.523 (4) | C11—H11A | 0.9700 |
C8—C9 | 1.548 (3) | C11—H11B | 0.9700 |
C8—C14 | 1.503 (4) | C12—H12A | 0.9700 |
C9—C10 | 1.559 (4) | C12—H12B | 0.9700 |
C9—C11 | 1.528 (3) | C15—H15 | 0.9300 |
C10—C19 | 1.517 (4) | C16—H16A | 0.9700 |
C11—C12 | 1.525 (4) | C16—H16B | 0.9700 |
C12—C13 | 1.532 (3) | C17—H17 | 0.9800 |
C13—C14 | 1.529 (3) | C18—H18A | 0.9600 |
C13—C17 | 1.559 (5) | C18—H18B | 0.9600 |
C13—C18 | 1.528 (5) | C18—H18C | 0.9600 |
C14—C15 | 1.333 (4) | C19—H19 | 0.9300 |
C15—C16 | 1.505 (5) | C21—H21 | 0.9300 |
C16—C17 | 1.528 (4) | C22—H22 | 0.9300 |
C17—C20 | 1.507 (5) | C23—H23 | 0.9300 |
C20—C21 | 1.355 (4) | ||
C21—O5—C24 | 120.8 (3) | C3—C2—H2A | 109.00 |
C3—O1—H1 | 110.00 | C3—C2—H2B | 109.00 |
C5—O2—H2 | 109.00 | H2A—C2—H2B | 108.00 |
C2—C1—C10 | 112.9 (2) | O1—C3—H3 | 109.00 |
C1—C2—C3 | 111.4 (2) | C2—C3—H3 | 109.00 |
O1—C3—C2 | 107.4 (2) | C4—C3—H3 | 109.00 |
O1—C3—C4 | 110.8 (3) | C3—C4—H4A | 109.00 |
C2—C3—C4 | 110.8 (2) | C3—C4—H4B | 109.00 |
C3—C4—C5 | 114.2 (3) | C5—C4—H4A | 109.00 |
O2—C5—C10 | 107.6 (2) | C5—C4—H4B | 109.00 |
C4—C5—C6 | 110.6 (3) | H4A—C4—H4B | 108.00 |
C4—C5—C10 | 111.3 (2) | C5—C6—H6A | 109.00 |
C6—C5—C10 | 111.9 (2) | C5—C6—H6B | 109.00 |
O2—C5—C6 | 106.6 (2) | C7—C6—H6A | 109.00 |
O2—C5—C4 | 108.6 (2) | C7—C6—H6B | 109.00 |
C5—C6—C7 | 112.8 (3) | H6A—C6—H6B | 108.00 |
C6—C7—C8 | 113.0 (3) | C6—C7—H7A | 109.00 |
C9—C8—C14 | 109.1 (2) | C6—C7—H7B | 109.00 |
C7—C8—C9 | 111.4 (2) | C8—C7—H7A | 109.00 |
C7—C8—C14 | 112.8 (3) | C8—C7—H7B | 109.00 |
C8—C9—C10 | 113.0 (2) | H7A—C7—H7B | 108.00 |
C8—C9—C11 | 110.72 (19) | C7—C8—H8 | 108.00 |
C10—C9—C11 | 113.7 (2) | C9—C8—H8 | 108.00 |
C1—C10—C5 | 108.88 (19) | C14—C8—H8 | 108.00 |
C5—C10—C9 | 109.7 (2) | C8—C9—H9 | 106.00 |
C5—C10—C19 | 109.3 (2) | C10—C9—H9 | 106.00 |
C9—C10—C19 | 108.9 (2) | C11—C9—H9 | 106.00 |
C1—C10—C9 | 112.3 (2) | C9—C11—H11A | 110.00 |
C1—C10—C19 | 107.7 (2) | C9—C11—H11B | 110.00 |
C9—C11—C12 | 110.5 (2) | C12—C11—H11A | 110.00 |
C11—C12—C13 | 112.8 (2) | C12—C11—H11B | 110.00 |
C12—C13—C17 | 112.0 (2) | H11A—C11—H11B | 108.00 |
C12—C13—C14 | 110.37 (18) | C11—C12—H12A | 109.00 |
C14—C13—C18 | 110.6 (2) | C11—C12—H12B | 109.00 |
C17—C13—C18 | 112.3 (2) | C13—C12—H12A | 109.00 |
C12—C13—C18 | 110.8 (2) | C13—C12—H12B | 109.00 |
C14—C13—C17 | 100.4 (2) | H12A—C12—H12B | 108.00 |
C13—C14—C15 | 110.7 (2) | C14—C15—H15 | 124.00 |
C8—C14—C13 | 120.8 (2) | C16—C15—H15 | 124.00 |
C8—C14—C15 | 128.5 (2) | C15—C16—H16A | 112.00 |
C14—C15—C16 | 111.9 (3) | C15—C16—H16B | 111.00 |
C15—C16—C17 | 101.6 (3) | C17—C16—H16A | 112.00 |
C13—C17—C20 | 116.0 (3) | C17—C16—H16B | 111.00 |
C16—C17—C20 | 118.3 (2) | H16A—C16—H16B | 109.00 |
C13—C17—C16 | 104.1 (2) | C13—C17—H17 | 106.00 |
O3—C19—C10 | 124.6 (3) | C16—C17—H17 | 106.00 |
C17—C20—C22 | 124.2 (3) | C20—C17—H17 | 106.00 |
C17—C20—C21 | 120.1 (3) | C13—C18—H18A | 109.00 |
C21—C20—C22 | 115.7 (3) | C13—C18—H18B | 110.00 |
O5—C21—C20 | 123.8 (3) | C13—C18—H18C | 109.00 |
C20—C22—C23 | 121.8 (3) | H18A—C18—H18B | 109.00 |
C22—C23—C24 | 123.0 (3) | H18A—C18—H18C | 109.00 |
O5—C24—C23 | 114.9 (3) | H18B—C18—H18C | 110.00 |
O4—C24—O5 | 118.9 (4) | O3—C19—H19 | 118.00 |
O4—C24—C23 | 126.2 (4) | C10—C19—H19 | 118.00 |
C2—C1—H1A | 109.00 | O5—C21—H21 | 118.00 |
C2—C1—H1B | 109.00 | C20—C21—H21 | 118.00 |
C10—C1—H1A | 109.00 | C20—C22—H22 | 119.00 |
C10—C1—H1B | 109.00 | C23—C22—H22 | 119.00 |
H1A—C1—H1B | 108.00 | C22—C23—H23 | 118.00 |
C1—C2—H2A | 109.00 | C24—C23—H23 | 119.00 |
C1—C2—H2B | 109.00 | ||
C24—O5—C21—C20 | −1.4 (8) | C11—C9—C10—C1 | 58.1 (3) |
C21—O5—C24—O4 | 179.1 (5) | C11—C9—C10—C5 | 179.4 (2) |
C21—O5—C24—C23 | −0.3 (7) | C11—C9—C10—C19 | −61.1 (3) |
C10—C1—C2—C3 | 57.9 (3) | C8—C9—C11—C12 | 61.7 (3) |
C2—C1—C10—C5 | −56.2 (3) | C10—C9—C11—C12 | −169.8 (2) |
C2—C1—C10—C9 | 65.5 (3) | C1—C10—C19—O3 | −14.4 (4) |
C2—C1—C10—C19 | −174.6 (2) | C5—C10—C19—O3 | −132.5 (3) |
C1—C2—C3—O1 | 67.1 (3) | C9—C10—C19—O3 | 107.6 (3) |
C1—C2—C3—C4 | −54.0 (3) | C9—C11—C12—C13 | −58.5 (3) |
O1—C3—C4—C5 | −66.2 (3) | C11—C12—C13—C14 | 46.1 (3) |
C2—C3—C4—C5 | 52.8 (3) | C11—C12—C13—C17 | 157.0 (2) |
C3—C4—C5—O2 | 65.4 (3) | C11—C12—C13—C18 | −76.8 (3) |
C3—C4—C5—C6 | −177.9 (3) | C12—C13—C14—C8 | −42.0 (4) |
C3—C4—C5—C10 | −52.9 (3) | C12—C13—C14—C15 | 138.7 (3) |
O2—C5—C6—C7 | −171.8 (3) | C17—C13—C14—C8 | −160.3 (2) |
C4—C5—C6—C7 | 70.3 (3) | C17—C13—C14—C15 | 20.4 (3) |
C10—C5—C6—C7 | −54.4 (4) | C18—C13—C14—C8 | 81.0 (3) |
O2—C5—C10—C1 | −66.4 (3) | C18—C13—C14—C15 | −98.3 (3) |
O2—C5—C10—C9 | 170.4 (2) | C12—C13—C17—C16 | −148.9 (2) |
O2—C5—C10—C19 | 51.1 (3) | C12—C13—C17—C20 | 79.3 (3) |
C4—C5—C10—C1 | 52.5 (3) | C14—C13—C17—C16 | −31.8 (3) |
C4—C5—C10—C9 | −70.7 (3) | C14—C13—C17—C20 | −163.6 (2) |
C4—C5—C10—C19 | 169.9 (2) | C18—C13—C17—C16 | 85.7 (3) |
C6—C5—C10—C1 | 176.8 (3) | C18—C13—C17—C20 | −46.1 (3) |
C6—C5—C10—C9 | 53.6 (3) | C8—C14—C15—C16 | −179.7 (3) |
C6—C5—C10—C19 | −65.8 (3) | C13—C14—C15—C16 | −0.4 (4) |
C5—C6—C7—C8 | 53.6 (4) | C14—C15—C16—C17 | −20.3 (4) |
C6—C7—C8—C9 | −52.0 (4) | C15—C16—C17—C13 | 31.8 (3) |
C6—C7—C8—C14 | −175.2 (3) | C15—C16—C17—C20 | 162.3 (3) |
C7—C8—C9—C10 | 52.9 (3) | C13—C17—C20—C21 | −85.2 (4) |
C7—C8—C9—C11 | −178.3 (3) | C13—C17—C20—C22 | 93.2 (4) |
C14—C8—C9—C10 | 178.1 (2) | C16—C17—C20—C21 | 149.9 (4) |
C14—C8—C9—C11 | −53.1 (3) | C16—C17—C20—C22 | −31.7 (5) |
C7—C8—C14—C13 | 169.8 (2) | C17—C20—C21—O5 | −179.0 (4) |
C7—C8—C14—C15 | −10.9 (4) | C22—C20—C21—O5 | 2.4 (7) |
C9—C8—C14—C13 | 45.4 (3) | C17—C20—C22—C23 | 179.8 (4) |
C9—C8—C14—C15 | −135.3 (3) | C21—C20—C22—C23 | −1.8 (6) |
C8—C9—C10—C1 | −174.6 (2) | C20—C22—C23—C24 | 0.1 (7) |
C8—C9—C10—C5 | −53.4 (3) | C22—C23—C24—O4 | −178.4 (5) |
C8—C9—C10—C19 | 66.2 (3) | C22—C23—C24—O5 | 0.9 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1 | 0.82 | 2.05 | 2.773 (3) | 147 |
O1—H1···O2i | 0.82 | 2.01 | 2.786 (3) | 158 |
C9—H9···O3ii | 0.98 | 2.58 | 3.545 (4) | 169 |
C15—H15···O4iii | 0.93 | 2.58 | 3.447 (4) | 155 |
C22—H22···O4iv | 0.93 | 2.60 | 3.233 (6) | 126 |
Symmetry codes: (i) −x+1, y−1/2, −z+2; (ii) x, y−1, z; (iii) x+1, y, z; (iv) −x−1, y+1/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C24H30O5 |
Mr | 398.48 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 291 |
a, b, c (Å) | 10.7628 (4), 6.6016 (2), 14.6376 (5) |
β (°) | 94.224 (3) |
V (Å3) | 1037.20 (6) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 0.71 |
Crystal size (mm) | 0.40 × 0.26 × 0.23 |
Data collection | |
Diffractometer | Oxford Gemini S Ultra Sapphire CCD diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2011) |
Tmin, Tmax | 0.819, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3100, 2238, 2042 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.576 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.115, 1.04 |
No. of reflections | 2238 |
No. of parameters | 266 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.20 |
Computer programs: CrysAlis PRO (Agilent, 2011), XPREP (Sheldrick, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP in SHELXTL (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1 | 0.82 | 2.05 | 2.773 (3) | 147 |
O1—H1···O2i | 0.82 | 2.01 | 2.786 (3) | 158 |
C9—H9···O3ii | 0.98 | 2.58 | 3.545 (4) | 169 |
C15—H15···O4iii | 0.93 | 2.58 | 3.447 (4) | 155 |
C22—H22···O4iv | 0.93 | 2.60 | 3.233 (6) | 126 |
Symmetry codes: (i) −x+1, y−1/2, −z+2; (ii) x, y−1, z; (iii) x+1, y, z; (iv) −x−1, y+1/2, −z+1. |
Acknowledgements
This work was supported by a grant from the National Science Foundation of China (21072078), Guangdong High Level Talent Scheme and the Fundamental Research Funds for the Central Universities (21609202).
References
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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.
Hellebrigenin is a cardiac steroid that exists in the skin of toads (Urscheler, et al., 1955; Zhao, et al., 2010)) and the rhizomes of Helleborus thibetanus (Yang, et al., 2010). It is an inhibitor of adenosinetriphosphatase. The 3-acetate, 3,5-diacetate, 3-iodoacetate and 3-bromoacetate of hellebrigenin were shown to be potent irreversible inhibitors of the enzyme (Ruoho, et al., 1968). The lactone ring at atom C17 is not stable at base conditions. Treatment of hellebrigenin with sodium hydroxide in methanol afforded methyl isohellebrigeninate (Kupchan, et al., 1969). While treatment of hellebrigenin with N,N-dimethylformamide (DMF) resulted in a derivative named as secohellebrigeninamide (Yuan et al., 2012). Recently, hellebrigenin was treated with hydrochloric acid and the new derivative 14,15-didehydro hellebrigenin was obtained, and we report herein on its crystal structure.
The title molecule (Fig. 1) is composed of three cyclohexane rings (A, B and C), an unsaturated five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. The cyclohexane rings A, B and C have normal chair conformations. The unsaturated five-membered ring D adopts an envelope conformation. The lactone ring E is planar with a mean derivation of 0.006 (4) Å and is β-oriented at C17 in ring D. The mean planes of the lactone ring E and ring D (atoms C13/C14/C15/C16) make a dihedral angle of 59.6 (1)°. There is an O-H···O hydrogen bond in the molecule involving the hydroxyl groups (Table 1).
In the crystal, O—H···O hydrogen bonds between the hydroxyl group at C3 and the hydroxyl group at C5 link adjacent molecules into dimers (Fig 2 and Table 1). Adjacent dimers are linked by short C–H···O contacts, between the methylene group at C6 and the lactone group, to form a three-dimensional network (Table 1 and Fig. 2).
The absolute configuration determined for bufalin (Rohrer et al., 1982) and secohellebrigeninamide, (Yuan et al., 2012), two similar steroids, were invoked, giving the assignments of the chiral centres in the molecule as shown in Fig. 1.