organic compounds
(+)-Methyl 3β-acetoxy-13-carboxy-19-hydroxy-11-oxo-C-norolean-18-en-30-oate γ-lactone
aInstitute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9/163, A-1060 Vienna, Austria, and bInstitute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164SC, A-1060 Vienna, Austria
*Correspondence e-mail: kurt.mereiter@tuwien.ac.at
The title compound, C33H46O7, is an unusual oxydation product of the therapeutic agent glycyrrhetinic acid that has, in comparison to the latter, a distinctly altered triterpene structure with one five- and four six-membered carbocycles complemented by a γ-lactone ring with a spiro-junction and a ring double bond. The junction between the five-membered ring C, a cyclopentanone ring, and the six-membered ring D, previously in question, was found to be cis, confirming earlier structure assignments based solely on chemical transformations. In the solid state, the compound exhibits five intra- and four intermolecular C—H⋯O interactions with H⋯O distances less than or equal to 2.70 Å and C—H⋯O greater than 100°.
Related literature
For the synthesis and structure elucidation of the title compound by chemical methods, see: Brownlie & Spring (1956); Jeger et al. (1944). For overviews of the therapeutic aspects of the parent compounds glycyrrhetinic acid and glycyrrhizin, see: Asl & Hosseinzadeh (2008); Baran et al. (1974); Kitagawa (2002). For recent research on the synthesis of new derivatives of glycyrrhetinic acid and their medicinal potency, see: Classen-Houben et al. (2009); Beseda et al. (2010); Amer et al. (2010).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT, SADABS and XPREP (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).
Supporting information
10.1107/S1600536810036901/bt5349sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536810036901/bt5349Isup2.hkl
The title compound was synthesized similar to the method of Brownlie & Spring (1956). To a solution of methyl glycyrrhetate acetate (500 mg, 0.98 mmol) in glacial acetic acid (30 ml) was added selenium dioxide (500 mg, 4.51 mmol) and the mixture stirred at 120 °C oil bath temperature. After 24 h the solvent was removed under vacuum, the residue diluted with water (100 ml) and extracted with dichloromethane (3 × 40 ml). The combined organic phase was washed with brine (10 ml) and dried over MgSO4. The δ 4.46 (m,1H), 3.72 (s, 3H), 3.07 (s, 1H), 2.60 (m, 1H), 2.04 (s, 3H), 2.18–0.80 (m, 19H),1.42 (s, 3H), 1.182 (s, 3H), 1.15 (s, 6H), 1.09 (s, 3H), 0.88 (s, 3H). 13C NMR (50 MHz, CDCl3): δ 203.8, 174.6, 174.3, 170.7, 151.4, 119.1, 80.3, 67.6, 65.5, 55.1, 52.7, 48.3,43.2, 42.3, 37.7, 36.6, 36.3, 35.6, 35.1, 33.9, 32.6, 31.2, 30.6, 28.0, 26.7,26.6, 23.2, 23.0, 21.2, 21.0, 18.8, 17.1, 16.3.
was removed by filtration, and the filtrate transferred to a round-bottom flask. The solution was evaporated to a constant weight with a rotary evaporator to leave 180 mg (36%) of pale-yellow material. An analytical sample was obtained by recrystallization from ethanol and melted at 291–292 °C. 1H NMR (200 MHz, CDCl3):All H atoms were placed in calculated positions and thereafter treated as riding. A torsional parameter was refined for each methyl group. Uiso(H) = 1.2Ueq(Cnon-methyl) and Uiso(H) = 1.5Ueq(Cmethyl) were used. Prior to final
the 3554 Friedel pairs were merged.Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT, SADABS and XPREP (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).Fig. 1. The molecular structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level. | |
Fig. 2. The molecular structure of (I) in a side-view showing the conformation of the rings more clearly. Hydrogen atoms omitted for clarity. | |
Fig. 3. Molecular structure of (I) (top) in comparison with the parent compound glycyrrhetinic acid (bottom) in its DMSO solvate (Beseda et al., 2010). Hydrogen atoms omitted for clarity, ring designation in large italics (only for bottom molecule), configuration of the asymmetric carbon atoms green (I), blue arrows indicate the C=C double bonds. Atom numeration in (I) follows a widely accepted designation in glycyrrhetinic acid. | |
Fig. 4. Packing diagram of (I) in a view down the a axis. Hydrogen atoms omitted for clarity. |
C33H46O7 | Dx = 1.285 Mg m−3 |
Mr = 554.70 | Melting point: 565 K |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 9893 reflections |
a = 7.6310 (4) Å | θ = 2.6–30.5° |
b = 16.7922 (9) Å | µ = 0.09 mm−1 |
c = 22.3822 (13) Å | T = 100 K |
V = 2868.1 (3) Å3 | Prism, colourless |
Z = 4 | 0.56 × 0.44 × 0.32 mm |
F(000) = 1200 |
Bruker Kappa APEXII CCD diffractometer | 4654 independent reflections |
Radiation source: fine-focus sealed tube | 4540 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
ϕ and ω scans | θmax = 30.0°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −10→10 |
Tmin = 0.88, Tmax = 0.97 | k = −23→22 |
41398 measured reflections | l = −30→31 |
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0571P)2 + 0.3708P] where P = (Fo2 + 2Fc2)/3 |
4654 reflections | (Δ/σ)max < 0.001 |
370 parameters | Δρmax = 0.34 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C33H46O7 | V = 2868.1 (3) Å3 |
Mr = 554.70 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.6310 (4) Å | µ = 0.09 mm−1 |
b = 16.7922 (9) Å | T = 100 K |
c = 22.3822 (13) Å | 0.56 × 0.44 × 0.32 mm |
Bruker Kappa APEXII CCD diffractometer | 4654 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 4540 reflections with I > 2σ(I) |
Tmin = 0.88, Tmax = 0.97 | Rint = 0.026 |
41398 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.34 e Å−3 |
4654 reflections | Δρmin = −0.19 e Å−3 |
370 parameters |
Geometry. All e.s.d.'s 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. |
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 | 0.58647 (12) | 0.36304 (5) | 0.59280 (3) | 0.01542 (16) | |
O2 | 0.21014 (12) | 0.38578 (6) | 0.30563 (4) | 0.02061 (18) | |
O3 | 0.07765 (16) | 0.16391 (6) | 0.05217 (4) | 0.0278 (2) | |
O4 | 0.02940 (13) | 0.20027 (5) | 0.14712 (4) | 0.02104 (18) | |
O5 | 0.49099 (13) | 0.23786 (5) | 0.60940 (4) | 0.02102 (18) | |
O6 | 0.51640 (14) | 0.21478 (5) | 0.28433 (4) | 0.02095 (19) | |
O7 | 0.38773 (12) | 0.22126 (5) | 0.19472 (4) | 0.01530 (16) | |
C1 | 0.38579 (15) | 0.34494 (7) | 0.43805 (5) | 0.01347 (19) | |
H1A | 0.2624 | 0.3473 | 0.4245 | 0.016* | |
H1B | 0.4337 | 0.2923 | 0.4267 | 0.016* | |
C2 | 0.39189 (15) | 0.35369 (7) | 0.50625 (5) | 0.0144 (2) | |
H2A | 0.3375 | 0.4049 | 0.5180 | 0.017* | |
H2B | 0.3242 | 0.3100 | 0.5250 | 0.017* | |
C3 | 0.57997 (15) | 0.35113 (7) | 0.52821 (5) | 0.01303 (19) | |
H3 | 0.6294 | 0.2974 | 0.5190 | 0.016* | |
C4 | 0.70187 (15) | 0.41476 (6) | 0.50091 (5) | 0.01278 (19) | |
C5 | 0.68261 (15) | 0.40901 (6) | 0.43176 (5) | 0.01175 (19) | |
H5 | 0.7267 | 0.3546 | 0.4217 | 0.014* | |
C6 | 0.80504 (16) | 0.46575 (7) | 0.39755 (5) | 0.0160 (2) | |
H6A | 0.9228 | 0.4647 | 0.4161 | 0.019* | |
H6B | 0.7594 | 0.5208 | 0.4005 | 0.019* | |
C7 | 0.82026 (15) | 0.44215 (7) | 0.33124 (5) | 0.0155 (2) | |
H7A | 0.8955 | 0.4812 | 0.3103 | 0.019* | |
H7B | 0.8769 | 0.3893 | 0.3282 | 0.019* | |
C8 | 0.64014 (15) | 0.43912 (6) | 0.30072 (5) | 0.01179 (18) | |
C9 | 0.51682 (14) | 0.38750 (6) | 0.34039 (4) | 0.01017 (18) | |
H9 | 0.5757 | 0.3343 | 0.3420 | 0.012* | |
C10 | 0.49178 (14) | 0.41083 (6) | 0.40651 (5) | 0.01149 (18) | |
C11 | 0.36470 (15) | 0.37522 (6) | 0.29852 (5) | 0.01211 (19) | |
C12 | 0.46147 (16) | 0.25521 (6) | 0.24456 (5) | 0.0144 (2) | |
C13 | 0.45088 (15) | 0.34696 (6) | 0.23907 (5) | 0.01111 (18) | |
C14 | 0.63502 (14) | 0.39140 (6) | 0.23874 (5) | 0.01162 (18) | |
C15 | 0.64754 (15) | 0.44362 (7) | 0.18159 (5) | 0.0145 (2) | |
H15A | 0.7407 | 0.4837 | 0.1881 | 0.017* | |
H15B | 0.6864 | 0.4090 | 0.1483 | 0.017* | |
C16 | 0.48210 (16) | 0.48775 (7) | 0.16123 (5) | 0.0156 (2) | |
H16A | 0.5100 | 0.5191 | 0.1250 | 0.019* | |
H16B | 0.4464 | 0.5256 | 0.1929 | 0.019* | |
C17 | 0.32639 (15) | 0.43173 (6) | 0.14723 (5) | 0.01265 (19) | |
C18 | 0.35306 (14) | 0.35531 (6) | 0.18125 (5) | 0.01168 (19) | |
C19 | 0.32842 (15) | 0.28331 (6) | 0.15797 (5) | 0.01295 (19) | |
C20 | 0.27038 (16) | 0.26123 (7) | 0.09642 (5) | 0.0144 (2) | |
C21 | 0.20702 (17) | 0.33903 (7) | 0.06549 (5) | 0.0171 (2) | |
H21A | 0.2051 | 0.3309 | 0.0217 | 0.021* | |
H21B | 0.0859 | 0.3510 | 0.0786 | 0.021* | |
C22 | 0.32516 (17) | 0.41004 (7) | 0.08013 (5) | 0.0157 (2) | |
H22A | 0.2851 | 0.4568 | 0.0569 | 0.019* | |
H22B | 0.4463 | 0.3976 | 0.0674 | 0.019* | |
C23 | 0.89158 (16) | 0.39174 (7) | 0.51797 (5) | 0.0168 (2) | |
H23A | 0.8966 | 0.3786 | 0.5606 | 0.025* | |
H23B | 0.9701 | 0.4366 | 0.5097 | 0.025* | |
H23C | 0.9283 | 0.3454 | 0.4944 | 0.025* | |
C24 | 0.66240 (17) | 0.49816 (7) | 0.52613 (5) | 0.0168 (2) | |
H24A | 0.6884 | 0.4991 | 0.5690 | 0.025* | |
H24B | 0.5384 | 0.5108 | 0.5198 | 0.025* | |
H24C | 0.7353 | 0.5377 | 0.5056 | 0.025* | |
C25 | 0.39079 (17) | 0.48996 (7) | 0.41380 (5) | 0.0171 (2) | |
H25A | 0.3027 | 0.4945 | 0.3821 | 0.026* | |
H25B | 0.4729 | 0.5347 | 0.4110 | 0.026* | |
H25C | 0.3327 | 0.4909 | 0.4528 | 0.026* | |
C26 | 0.57387 (17) | 0.52513 (6) | 0.29370 (5) | 0.0169 (2) | |
H26A | 0.5942 | 0.5545 | 0.3309 | 0.025* | |
H26B | 0.4482 | 0.5246 | 0.2848 | 0.025* | |
H26C | 0.6370 | 0.5511 | 0.2610 | 0.025* | |
C27 | 0.78590 (16) | 0.33104 (7) | 0.23470 (5) | 0.0165 (2) | |
H27A | 0.7713 | 0.2983 | 0.1988 | 0.025* | |
H27B | 0.7849 | 0.2968 | 0.2702 | 0.025* | |
H27C | 0.8978 | 0.3596 | 0.2326 | 0.025* | |
C28 | 0.15441 (17) | 0.47305 (7) | 0.16436 (6) | 0.0181 (2) | |
H28A | 0.1514 | 0.4816 | 0.2077 | 0.027* | |
H28B | 0.0552 | 0.4395 | 0.1525 | 0.027* | |
H28C | 0.1467 | 0.5245 | 0.1438 | 0.027* | |
C29 | 0.11726 (16) | 0.20249 (7) | 0.09537 (5) | 0.0166 (2) | |
C30 | 0.42425 (19) | 0.22355 (8) | 0.06203 (6) | 0.0219 (2) | |
H30A | 0.4667 | 0.1767 | 0.0838 | 0.033* | |
H30B | 0.5193 | 0.2625 | 0.0583 | 0.033* | |
H30C | 0.3847 | 0.2075 | 0.0222 | 0.033* | |
C31 | 0.54224 (16) | 0.30102 (7) | 0.62791 (5) | 0.0152 (2) | |
C32 | 0.5655 (2) | 0.32204 (8) | 0.69276 (5) | 0.0236 (3) | |
H32A | 0.5682 | 0.2732 | 0.7167 | 0.035* | |
H32B | 0.4675 | 0.3555 | 0.7059 | 0.035* | |
H32C | 0.6758 | 0.3511 | 0.6980 | 0.035* | |
C33 | −0.11701 (18) | 0.14577 (8) | 0.14807 (7) | 0.0252 (3) | |
H33A | −0.1760 | 0.1490 | 0.1869 | 0.038* | |
H33B | −0.0746 | 0.0914 | 0.1416 | 0.038* | |
H33C | −0.1998 | 0.1600 | 0.1163 | 0.038* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0208 (4) | 0.0152 (3) | 0.0103 (3) | −0.0016 (3) | −0.0006 (3) | −0.0002 (3) |
O2 | 0.0112 (4) | 0.0337 (5) | 0.0169 (4) | 0.0005 (4) | 0.0006 (3) | 0.0015 (4) |
O3 | 0.0385 (6) | 0.0258 (5) | 0.0192 (4) | −0.0091 (5) | −0.0060 (4) | −0.0045 (3) |
O4 | 0.0193 (4) | 0.0213 (4) | 0.0225 (4) | −0.0068 (4) | 0.0010 (4) | −0.0053 (3) |
O5 | 0.0262 (5) | 0.0170 (4) | 0.0199 (4) | −0.0032 (4) | −0.0017 (4) | 0.0010 (3) |
O6 | 0.0302 (5) | 0.0131 (4) | 0.0195 (4) | −0.0009 (4) | −0.0085 (4) | 0.0036 (3) |
O7 | 0.0206 (4) | 0.0104 (3) | 0.0149 (3) | 0.0002 (3) | −0.0048 (3) | 0.0009 (3) |
C1 | 0.0123 (4) | 0.0160 (5) | 0.0121 (4) | −0.0032 (4) | 0.0002 (4) | 0.0012 (4) |
C2 | 0.0129 (5) | 0.0186 (5) | 0.0118 (4) | −0.0017 (4) | 0.0004 (4) | 0.0005 (4) |
C3 | 0.0150 (5) | 0.0141 (4) | 0.0100 (4) | −0.0010 (4) | −0.0005 (4) | −0.0011 (4) |
C4 | 0.0131 (4) | 0.0135 (4) | 0.0117 (4) | −0.0007 (4) | −0.0003 (4) | −0.0024 (4) |
C5 | 0.0106 (4) | 0.0136 (4) | 0.0111 (4) | −0.0010 (4) | −0.0003 (4) | −0.0015 (3) |
C6 | 0.0156 (5) | 0.0194 (5) | 0.0131 (5) | −0.0073 (4) | 0.0004 (4) | −0.0013 (4) |
C7 | 0.0117 (4) | 0.0210 (5) | 0.0137 (4) | −0.0047 (4) | 0.0007 (4) | −0.0005 (4) |
C8 | 0.0115 (4) | 0.0116 (4) | 0.0122 (4) | −0.0015 (4) | 0.0016 (4) | −0.0008 (3) |
C9 | 0.0094 (4) | 0.0107 (4) | 0.0105 (4) | −0.0008 (4) | 0.0005 (3) | 0.0003 (3) |
C10 | 0.0108 (4) | 0.0126 (4) | 0.0110 (4) | 0.0000 (4) | 0.0006 (4) | −0.0003 (4) |
C11 | 0.0119 (4) | 0.0129 (4) | 0.0116 (4) | −0.0014 (4) | 0.0002 (4) | 0.0020 (3) |
C12 | 0.0163 (5) | 0.0116 (4) | 0.0154 (5) | −0.0012 (4) | −0.0020 (4) | 0.0004 (4) |
C13 | 0.0122 (4) | 0.0101 (4) | 0.0110 (4) | −0.0009 (4) | −0.0010 (4) | 0.0015 (3) |
C14 | 0.0100 (4) | 0.0128 (4) | 0.0121 (4) | −0.0005 (4) | 0.0008 (4) | 0.0002 (3) |
C15 | 0.0142 (5) | 0.0162 (5) | 0.0133 (4) | −0.0020 (4) | 0.0018 (4) | 0.0023 (4) |
C16 | 0.0176 (5) | 0.0133 (4) | 0.0160 (5) | −0.0027 (4) | −0.0023 (4) | 0.0038 (4) |
C17 | 0.0130 (4) | 0.0124 (4) | 0.0126 (4) | 0.0005 (4) | −0.0005 (4) | 0.0028 (3) |
C18 | 0.0111 (4) | 0.0126 (4) | 0.0113 (4) | 0.0000 (4) | 0.0001 (4) | 0.0017 (3) |
C19 | 0.0142 (5) | 0.0124 (4) | 0.0122 (4) | 0.0004 (4) | −0.0013 (4) | 0.0020 (3) |
C20 | 0.0165 (5) | 0.0143 (4) | 0.0123 (4) | 0.0001 (4) | −0.0011 (4) | −0.0006 (4) |
C21 | 0.0215 (5) | 0.0161 (5) | 0.0138 (4) | −0.0008 (4) | −0.0046 (4) | 0.0021 (4) |
C22 | 0.0194 (5) | 0.0156 (5) | 0.0120 (4) | −0.0010 (4) | −0.0011 (4) | 0.0032 (4) |
C23 | 0.0138 (5) | 0.0213 (5) | 0.0153 (5) | 0.0000 (4) | −0.0023 (4) | −0.0027 (4) |
C24 | 0.0218 (5) | 0.0138 (5) | 0.0149 (4) | −0.0021 (4) | 0.0002 (4) | −0.0037 (4) |
C25 | 0.0190 (5) | 0.0161 (5) | 0.0162 (5) | 0.0052 (4) | 0.0020 (4) | 0.0001 (4) |
C26 | 0.0235 (6) | 0.0110 (4) | 0.0162 (5) | 0.0004 (4) | 0.0024 (4) | 0.0007 (4) |
C27 | 0.0136 (5) | 0.0188 (5) | 0.0171 (5) | 0.0047 (4) | 0.0013 (4) | −0.0020 (4) |
C28 | 0.0169 (5) | 0.0171 (5) | 0.0202 (5) | 0.0051 (4) | 0.0010 (4) | 0.0026 (4) |
C29 | 0.0194 (5) | 0.0136 (4) | 0.0169 (5) | 0.0005 (4) | −0.0046 (4) | 0.0005 (4) |
C30 | 0.0234 (6) | 0.0229 (6) | 0.0194 (5) | 0.0027 (5) | 0.0034 (5) | −0.0034 (4) |
C31 | 0.0146 (5) | 0.0167 (5) | 0.0144 (5) | 0.0019 (4) | −0.0008 (4) | 0.0022 (4) |
C32 | 0.0364 (7) | 0.0214 (5) | 0.0130 (5) | −0.0019 (5) | −0.0025 (5) | 0.0018 (4) |
C33 | 0.0185 (5) | 0.0212 (5) | 0.0359 (7) | −0.0065 (5) | −0.0001 (5) | −0.0029 (5) |
O1—C31 | 1.3475 (13) | C15—H15B | 0.9900 |
O1—C3 | 1.4603 (12) | C16—C17 | 1.5476 (16) |
O2—C11 | 1.2033 (15) | C16—H16A | 0.9900 |
O3—C29 | 1.2025 (15) | C16—H16B | 0.9900 |
O4—C29 | 1.3389 (15) | C17—C18 | 1.5059 (14) |
O4—C33 | 1.4444 (15) | C17—C28 | 1.5332 (16) |
O5—C31 | 1.2039 (15) | C17—C22 | 1.5455 (15) |
O6—C12 | 1.1953 (14) | C18—C19 | 1.3299 (15) |
O7—C12 | 1.3735 (13) | C19—C20 | 1.4939 (15) |
O7—C19 | 1.4024 (13) | C20—C29 | 1.5293 (17) |
C1—C2 | 1.5342 (15) | C20—C30 | 1.5400 (17) |
C1—C10 | 1.5416 (15) | C20—C21 | 1.5554 (16) |
C1—H1A | 0.9900 | C21—C22 | 1.5304 (17) |
C1—H1B | 0.9900 | C21—H21A | 0.9900 |
C2—C3 | 1.5177 (16) | C21—H21B | 0.9900 |
C2—H2A | 0.9900 | C22—H22A | 0.9900 |
C2—H2B | 0.9900 | C22—H22B | 0.9900 |
C3—C4 | 1.5428 (16) | C23—H23A | 0.9800 |
C3—H3 | 1.0000 | C23—H23B | 0.9800 |
C4—C24 | 1.5397 (15) | C23—H23C | 0.9800 |
C4—C23 | 1.5463 (16) | C24—H24A | 0.9800 |
C4—C5 | 1.5575 (14) | C24—H24B | 0.9800 |
C5—C6 | 1.5385 (15) | C24—H24C | 0.9800 |
C5—C10 | 1.5624 (15) | C25—H25A | 0.9800 |
C5—H5 | 1.0000 | C25—H25B | 0.9800 |
C6—C7 | 1.5407 (15) | C25—H25C | 0.9800 |
C6—H6A | 0.9900 | C26—H26A | 0.9800 |
C6—H6B | 0.9900 | C26—H26B | 0.9800 |
C7—C8 | 1.5356 (16) | C26—H26C | 0.9800 |
C7—H7A | 0.9900 | C27—H27A | 0.9800 |
C7—H7B | 0.9900 | C27—H27B | 0.9800 |
C8—C26 | 1.5382 (15) | C27—H27C | 0.9800 |
C8—C9 | 1.5573 (14) | C28—H28A | 0.9800 |
C8—C14 | 1.6026 (15) | C28—H28B | 0.9800 |
C9—C11 | 1.5061 (15) | C28—H28C | 0.9800 |
C9—C10 | 1.5429 (14) | C30—H30A | 0.9800 |
C9—H9 | 1.0000 | C30—H30B | 0.9800 |
C10—C25 | 1.5448 (15) | C30—H30C | 0.9800 |
C11—C13 | 1.5582 (15) | C31—C32 | 1.5044 (16) |
C12—C13 | 1.5478 (15) | C32—H32A | 0.9800 |
C13—C18 | 1.5006 (14) | C32—H32B | 0.9800 |
C13—C14 | 1.5910 (15) | C32—H32C | 0.9800 |
C14—C27 | 1.5366 (15) | C33—H33A | 0.9800 |
C14—C15 | 1.5538 (15) | C33—H33B | 0.9800 |
C15—C16 | 1.5332 (16) | C33—H33C | 0.9800 |
C15—H15A | 0.9900 | ||
C31—O1—C3 | 117.58 (9) | H16A—C16—H16B | 107.7 |
C29—O4—C33 | 114.68 (10) | C18—C17—C28 | 112.02 (9) |
C12—O7—C19 | 107.47 (8) | C18—C17—C22 | 106.94 (8) |
C2—C1—C10 | 111.77 (9) | C28—C17—C22 | 110.15 (9) |
C2—C1—H1A | 109.3 | C18—C17—C16 | 108.17 (9) |
C10—C1—H1A | 109.3 | C28—C17—C16 | 109.36 (9) |
C2—C1—H1B | 109.3 | C22—C17—C16 | 110.15 (9) |
C10—C1—H1B | 109.3 | C19—C18—C13 | 108.86 (9) |
H1A—C1—H1B | 107.9 | C19—C18—C17 | 123.89 (9) |
C3—C2—C1 | 110.38 (9) | C13—C18—C17 | 125.65 (9) |
C3—C2—H2A | 109.6 | C18—C19—O7 | 113.59 (9) |
C1—C2—H2A | 109.6 | C18—C19—C20 | 128.96 (10) |
C3—C2—H2B | 109.6 | O7—C19—C20 | 116.88 (9) |
C1—C2—H2B | 109.6 | C19—C20—C29 | 113.62 (9) |
H2A—C2—H2B | 108.1 | C19—C20—C30 | 109.68 (10) |
O1—C3—C2 | 110.42 (9) | C29—C20—C30 | 108.05 (10) |
O1—C3—C4 | 106.08 (8) | C19—C20—C21 | 107.11 (9) |
C2—C3—C4 | 114.98 (9) | C29—C20—C21 | 107.30 (9) |
O1—C3—H3 | 108.4 | C30—C20—C21 | 111.08 (10) |
C2—C3—H3 | 108.4 | C22—C21—C20 | 112.09 (10) |
C4—C3—H3 | 108.4 | C22—C21—H21A | 109.2 |
C24—C4—C3 | 111.51 (9) | C20—C21—H21A | 109.2 |
C24—C4—C23 | 108.66 (9) | C22—C21—H21B | 109.2 |
C3—C4—C23 | 107.07 (9) | C20—C21—H21B | 109.2 |
C24—C4—C5 | 113.72 (9) | H21A—C21—H21B | 107.9 |
C3—C4—C5 | 107.09 (9) | C21—C22—C17 | 113.28 (9) |
C23—C4—C5 | 108.56 (9) | C21—C22—H22A | 108.9 |
C6—C5—C4 | 113.51 (9) | C17—C22—H22A | 108.9 |
C6—C5—C10 | 111.95 (9) | C21—C22—H22B | 108.9 |
C4—C5—C10 | 116.50 (9) | C17—C22—H22B | 108.9 |
C6—C5—H5 | 104.4 | H22A—C22—H22B | 107.7 |
C4—C5—H5 | 104.4 | C4—C23—H23A | 109.5 |
C10—C5—H5 | 104.4 | C4—C23—H23B | 109.5 |
C5—C6—C7 | 111.47 (9) | H23A—C23—H23B | 109.5 |
C5—C6—H6A | 109.3 | C4—C23—H23C | 109.5 |
C7—C6—H6A | 109.3 | H23A—C23—H23C | 109.5 |
C5—C6—H6B | 109.3 | H23B—C23—H23C | 109.5 |
C7—C6—H6B | 109.3 | C4—C24—H24A | 109.5 |
H6A—C6—H6B | 108.0 | C4—C24—H24B | 109.5 |
C8—C7—C6 | 111.68 (9) | H24A—C24—H24B | 109.5 |
C8—C7—H7A | 109.3 | C4—C24—H24C | 109.5 |
C6—C7—H7A | 109.3 | H24A—C24—H24C | 109.5 |
C8—C7—H7B | 109.3 | H24B—C24—H24C | 109.5 |
C6—C7—H7B | 109.3 | C10—C25—H25A | 109.5 |
H7A—C7—H7B | 107.9 | C10—C25—H25B | 109.5 |
C7—C8—C26 | 107.97 (9) | H25A—C25—H25B | 109.5 |
C7—C8—C9 | 107.80 (8) | C10—C25—H25C | 109.5 |
C26—C8—C9 | 112.47 (9) | H25A—C25—H25C | 109.5 |
C7—C8—C14 | 115.05 (9) | H25B—C25—H25C | 109.5 |
C26—C8—C14 | 111.90 (9) | C8—C26—H26A | 109.5 |
C9—C8—C14 | 101.56 (8) | C8—C26—H26B | 109.5 |
C11—C9—C10 | 122.43 (9) | H26A—C26—H26B | 109.5 |
C11—C9—C8 | 100.79 (8) | C8—C26—H26C | 109.5 |
C10—C9—C8 | 118.71 (9) | H26A—C26—H26C | 109.5 |
C11—C9—H9 | 104.3 | H26B—C26—H26C | 109.5 |
C10—C9—H9 | 104.3 | C14—C27—H27A | 109.5 |
C8—C9—H9 | 104.3 | C14—C27—H27B | 109.5 |
C1—C10—C9 | 108.78 (8) | H27A—C27—H27B | 109.5 |
C1—C10—C25 | 107.90 (9) | C14—C27—H27C | 109.5 |
C9—C10—C25 | 112.43 (9) | H27A—C27—H27C | 109.5 |
C1—C10—C5 | 108.02 (8) | H27B—C27—H27C | 109.5 |
C9—C10—C5 | 103.10 (8) | C17—C28—H28A | 109.5 |
C25—C10—C5 | 116.33 (9) | C17—C28—H28B | 109.5 |
O2—C11—C9 | 130.77 (10) | H28A—C28—H28B | 109.5 |
O2—C11—C13 | 124.86 (10) | C17—C28—H28C | 109.5 |
C9—C11—C13 | 104.34 (9) | H28A—C28—H28C | 109.5 |
O6—C12—O7 | 120.85 (10) | H28B—C28—H28C | 109.5 |
O6—C12—C13 | 130.00 (10) | O3—C29—O4 | 123.70 (12) |
O7—C12—C13 | 109.11 (9) | O3—C29—C20 | 123.50 (11) |
C18—C13—C12 | 100.80 (9) | O4—C29—C20 | 112.78 (9) |
C18—C13—C11 | 119.87 (9) | C20—C30—H30A | 109.5 |
C12—C13—C11 | 104.91 (8) | C20—C30—H30B | 109.5 |
C18—C13—C14 | 113.05 (8) | H30A—C30—H30B | 109.5 |
C12—C13—C14 | 114.91 (9) | C20—C30—H30C | 109.5 |
C11—C13—C14 | 103.52 (8) | H30A—C30—H30C | 109.5 |
C27—C14—C15 | 106.12 (9) | H30B—C30—H30C | 109.5 |
C27—C14—C13 | 110.65 (9) | O5—C31—O1 | 124.17 (10) |
C15—C14—C13 | 108.83 (8) | O5—C31—C32 | 125.24 (11) |
C27—C14—C8 | 111.26 (9) | O1—C31—C32 | 110.60 (10) |
C15—C14—C8 | 115.40 (9) | C31—C32—H32A | 109.5 |
C13—C14—C8 | 104.60 (8) | C31—C32—H32B | 109.5 |
C16—C15—C14 | 117.84 (9) | H32A—C32—H32B | 109.5 |
C16—C15—H15A | 107.8 | C31—C32—H32C | 109.5 |
C14—C15—H15A | 107.8 | H32A—C32—H32C | 109.5 |
C16—C15—H15B | 107.8 | H32B—C32—H32C | 109.5 |
C14—C15—H15B | 107.8 | O4—C33—H33A | 109.5 |
H15A—C15—H15B | 107.2 | O4—C33—H33B | 109.5 |
C15—C16—C17 | 113.49 (9) | H33A—C33—H33B | 109.5 |
C15—C16—H16A | 108.9 | O4—C33—H33C | 109.5 |
C17—C16—H16A | 108.9 | H33A—C33—H33C | 109.5 |
C15—C16—H16B | 108.9 | H33B—C33—H33C | 109.5 |
C17—C16—H16B | 108.9 | ||
C10—C1—C2—C3 | −58.36 (12) | C11—C13—C14—C27 | 122.21 (9) |
C31—O1—C3—C2 | 76.94 (12) | C18—C13—C14—C15 | 9.68 (12) |
C31—O1—C3—C4 | −157.87 (9) | C12—C13—C14—C15 | 124.65 (10) |
C1—C2—C3—O1 | 177.46 (9) | C11—C13—C14—C15 | −121.55 (9) |
C1—C2—C3—C4 | 57.50 (12) | C18—C13—C14—C8 | 133.53 (9) |
O1—C3—C4—C24 | −49.35 (12) | C12—C13—C14—C8 | −111.49 (10) |
C2—C3—C4—C24 | 72.98 (12) | C11—C13—C14—C8 | 2.30 (10) |
O1—C3—C4—C23 | 69.39 (11) | C7—C8—C14—C27 | 23.18 (12) |
C2—C3—C4—C23 | −168.28 (9) | C26—C8—C14—C27 | 146.90 (10) |
O1—C3—C4—C5 | −174.34 (9) | C9—C8—C14—C27 | −92.92 (10) |
C2—C3—C4—C5 | −52.01 (12) | C7—C8—C14—C15 | −97.78 (11) |
C24—C4—C5—C6 | 59.79 (13) | C26—C8—C14—C15 | 25.93 (13) |
C3—C4—C5—C6 | −176.57 (9) | C9—C8—C14—C15 | 146.11 (9) |
C23—C4—C5—C6 | −61.28 (12) | C7—C8—C14—C13 | 142.69 (9) |
C24—C4—C5—C10 | −72.47 (12) | C26—C8—C14—C13 | −93.60 (10) |
C3—C4—C5—C10 | 51.18 (12) | C9—C8—C14—C13 | 26.58 (10) |
C23—C4—C5—C10 | 166.46 (9) | C27—C14—C15—C16 | 158.17 (10) |
C4—C5—C6—C7 | 163.94 (10) | C13—C14—C15—C16 | 39.06 (12) |
C10—C5—C6—C7 | −61.63 (12) | C8—C14—C15—C16 | −78.12 (12) |
C5—C6—C7—C8 | 56.45 (13) | C14—C15—C16—C17 | −59.65 (13) |
C6—C7—C8—C26 | 71.40 (11) | C15—C16—C17—C18 | 23.71 (13) |
C6—C7—C8—C9 | −50.35 (12) | C15—C16—C17—C28 | 145.97 (10) |
C6—C7—C8—C14 | −162.83 (9) | C15—C16—C17—C22 | −92.85 (11) |
C7—C8—C9—C11 | −167.72 (9) | C12—C13—C18—C19 | −4.12 (12) |
C26—C8—C9—C11 | 73.36 (10) | C11—C13—C18—C19 | −118.43 (11) |
C14—C8—C9—C11 | −46.42 (9) | C14—C13—C18—C19 | 119.06 (10) |
C7—C8—C9—C10 | 55.67 (12) | C12—C13—C18—C17 | −170.08 (10) |
C26—C8—C9—C10 | −63.26 (12) | C11—C13—C18—C17 | 75.61 (14) |
C14—C8—C9—C10 | 176.96 (9) | C14—C13—C18—C17 | −46.91 (14) |
C2—C1—C10—C9 | 166.68 (9) | C28—C17—C18—C19 | 103.47 (13) |
C2—C1—C10—C25 | −71.10 (11) | C22—C17—C18—C19 | −17.30 (15) |
C2—C1—C10—C5 | 55.43 (12) | C16—C17—C18—C19 | −135.92 (12) |
C11—C9—C10—C1 | 60.76 (12) | C28—C17—C18—C13 | −92.58 (13) |
C8—C9—C10—C1 | −172.31 (9) | C22—C17—C18—C13 | 146.65 (11) |
C11—C9—C10—C25 | −58.68 (13) | C16—C17—C18—C13 | 28.03 (14) |
C8—C9—C10—C25 | 68.25 (12) | C13—C18—C19—O7 | 4.12 (14) |
C11—C9—C10—C5 | 175.26 (9) | C17—C18—C19—O7 | 170.38 (10) |
C8—C9—C10—C5 | −57.82 (11) | C13—C18—C19—C20 | −166.81 (11) |
C6—C5—C10—C1 | 172.93 (9) | C17—C18—C19—C20 | −0.55 (19) |
C4—C5—C10—C1 | −54.10 (12) | C12—O7—C19—C18 | −2.10 (14) |
C6—C5—C10—C9 | 57.89 (11) | C12—O7—C19—C20 | 170.00 (10) |
C4—C5—C10—C9 | −169.14 (9) | C18—C19—C20—C29 | −129.02 (13) |
C6—C5—C10—C25 | −65.62 (11) | O7—C19—C20—C29 | 60.31 (14) |
C4—C5—C10—C25 | 67.34 (12) | C18—C19—C20—C30 | 109.94 (14) |
C10—C9—C11—O2 | 5.92 (19) | O7—C19—C20—C30 | −60.74 (13) |
C8—C9—C11—O2 | −128.53 (13) | C18—C19—C20—C21 | −10.71 (17) |
C10—C9—C11—C13 | −176.09 (9) | O7—C19—C20—C21 | 178.61 (10) |
C8—C9—C11—C13 | 49.45 (9) | C19—C20—C21—C22 | 40.24 (13) |
C19—O7—C12—O6 | 177.07 (12) | C29—C20—C21—C22 | 162.58 (10) |
C19—O7—C12—C13 | −0.79 (12) | C30—C20—C21—C22 | −79.52 (12) |
O6—C12—C13—C18 | −174.68 (13) | C20—C21—C22—C17 | −63.10 (13) |
O7—C12—C13—C18 | 2.92 (12) | C18—C17—C22—C21 | 47.71 (13) |
O6—C12—C13—C11 | −49.55 (17) | C28—C17—C22—C21 | −74.24 (12) |
O7—C12—C13—C11 | 128.06 (9) | C16—C17—C22—C21 | 165.04 (10) |
O6—C12—C13—C14 | 63.44 (17) | C33—O4—C29—O3 | 1.44 (18) |
O7—C12—C13—C14 | −118.96 (10) | C33—O4—C29—C20 | 179.73 (10) |
O2—C11—C13—C18 | 19.22 (17) | C19—C20—C29—O3 | −162.49 (12) |
C9—C11—C13—C18 | −158.92 (9) | C30—C20—C29—O3 | −40.54 (16) |
O2—C11—C13—C12 | −92.91 (14) | C21—C20—C29—O3 | 79.32 (14) |
C9—C11—C13—C12 | 88.95 (10) | C19—C20—C29—O4 | 19.21 (14) |
O2—C11—C13—C14 | 146.27 (12) | C30—C20—C29—O4 | 141.16 (10) |
C9—C11—C13—C14 | −31.87 (10) | C21—C20—C29—O4 | −98.98 (11) |
C18—C13—C14—C27 | −106.56 (10) | C3—O1—C31—O5 | −3.23 (18) |
C12—C13—C14—C27 | 8.41 (12) | C3—O1—C31—C32 | 176.93 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2B···O5 | 0.99 | 2.58 | 3.1121 (14) | 114 |
C9—H9···O6 | 1.00 | 2.43 | 3.1601 (13) | 129 |
C23—H23A···O1 | 0.98 | 2.49 | 2.9084 (15) | 106 |
C25—H25A···O2 | 0.98 | 2.60 | 3.2898 (16) | 127 |
C27—H27B···O6 | 0.98 | 2.49 | 3.0454 (16) | 116 |
C1—H1A···O5i | 0.99 | 2.63 | 3.4839 (15) | 145 |
C5—H5···O5ii | 1.00 | 2.64 | 3.5313 (14) | 149 |
C7—H7B···O2iii | 0.99 | 2.59 | 3.1743 (15) | 118 |
C7—H7B···O5ii | 0.99 | 2.70 | 3.5497 (15) | 145 |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x+1/2, −y+1/2, −z+1; (iii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C33H46O7 |
Mr | 554.70 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 100 |
a, b, c (Å) | 7.6310 (4), 16.7922 (9), 22.3822 (13) |
V (Å3) | 2868.1 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.56 × 0.44 × 0.32 |
Data collection | |
Diffractometer | Bruker Kappa APEXII CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2008) |
Tmin, Tmax | 0.88, 0.97 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 41398, 4654, 4540 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.080, 1.05 |
No. of reflections | 4654 |
No. of parameters | 370 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.19 |
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SAINT, SADABS and XPREP (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006), PLATON (Spek, 2009) and publCIF (Westrip, 2010).
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2B···O5 | 0.99 | 2.58 | 3.1121 (14) | 113.6 |
C9—H9···O6 | 1.00 | 2.43 | 3.1601 (13) | 129.4 |
C23—H23A···O1 | 0.98 | 2.49 | 2.9084 (15) | 105.6 |
C25—H25A···O2 | 0.98 | 2.60 | 3.2898 (16) | 127.4 |
C27—H27B···O6 | 0.98 | 2.49 | 3.0454 (16) | 115.8 |
C1—H1A···O5i | 0.99 | 2.63 | 3.4839 (15) | 144.7 |
C5—H5···O5ii | 1.00 | 2.64 | 3.5313 (14) | 148.7 |
C7—H7B···O2iii | 0.99 | 2.59 | 3.1743 (15) | 117.5 |
C7—H7B···O5ii | 0.99 | 2.70 | 3.5497 (15) | 144.6 |
Symmetry codes: (i) x−1/2, −y+1/2, −z+1; (ii) x+1/2, −y+1/2, −z+1; (iii) x+1, y, z. |
Acknowledgements
The work was supported by the ZIT Zentrum für Innovation und Technologie GmbH (Vienna Spot of Excellence, 182081).
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Glycyrrhetinic acid (18β-glycyrrhetinic acid, GA), a pentacyclic triterpenoid, is the aglycone of glycyrrhizin, the main sweet tasting compound from liquorice root that is in use as flavoring and sweetener in candies and food (Kitagawa, 2002). This compound has a long record as therapeutic agent with antiinflammatory, antiulcer, antiallergic, and other activity by being active towards 11β-hydroxysteroid dehydrogenases and consequently modulating the steroid hormone cortisol (Baran et al., 1974; Asl & Hosseinzadeh, 2008). With these features glycyrrhetinic acid is of ongoing interest for creating new derivatives aimed at improving or diversifying its therapeutical profile.
In context with corresponding research (Classen-Houben et al., 2009; Beseda et al., 2010; Amer et al., 2010) we came across the title compound, (I), which was of interest because it is an unusual derivative of glycyrrhetinic acid. Obtained initially by the Nobel laureate Ruzicka and his group (Jeger et al., 1944), it was later on synthesized from methyl glycyrrhetate acetate, C33H50O5, in a one-step reaction by oxydation with SeO2 under introduction of two more oxygen atoms, elimination of four hydrogen atoms, rearrangement of one ring, and generation of an additional unsaturated γ-lactone ring (Brownlie & Spring, 1956). The assignment of a structural formula to this compound was as yet based on combustion analysis, derivatizations, chemical tests for funtional groups and stereochemical considerations but not on present day methods like NMR spectroscopy. Therefore the structural formula of (I) was partly open to question and it was considered worth to secure it by X-ray crystallography.
The result of the present work is shown in Figures 1 and 2. In order to facilitate the discussion, a comparison of the molecular structure of (I) with the parent compound 18β-glycyrrhetinic acid (GA) is given in Fig. 3. This figure includes also the chiralities of the nine asymmetric carbon atoms in (I), which prove that the assignment of Brownlie & Spring (1956) is correct, which is of relevance for carbon C13 (crystallographic atom numbering). In both compounds, (I) and GA, are the six membered rings A and B adopting the usual chair conformation and having a trans-link. On transition from GA to (I), the cyclohex-2-enone ring C is oxydatively cleaved between C11 and C12 and transforms into a cyclopentanone ring, whereas the former sixth ring carbon, C12, is utilized to generate a new γ-lactone ring with a new double bond between C18 and C19. By this transformation the carbon C13, initially of sp2-type, becomes sp3-type and chiral with S-configuration, as proven by X-ray diffraction. Hence, the junction between rings C and D in (I) is of a cis-type. Compared with GA the introduction of the new γ-lactone ring and the double bond C18—C19 in (I) changes the conformation of rings D and E drastically, namely from chair and chair in GA to twist-boat and twisted half-chair in (I). Therefore the shape of the molecule in (I) is singificantly altered in comparison to GA and ordinary derivatives thereof (Beseda et al., 2010). Bond lengths and angles in (I), listed below are largely normal except for the two most congested carbon atoms C13 and C14 (both sp3), which show two notably elongated bonds (C13—C14 = 1.5910 (15) Å, C14—C8 = 1.6026 (15) Å) and two unusually large bond angles (C11—C13—C18 = 119.9 (1) ° and C8—C14—C15 = 115.4 (1) °). The double bond C18—C19 shared by rings E and F measures 1.3299 (15) Å. A packing diagram of (I) is shown in Fig. 4. Apart from five intramolecular C—H···O interactions there are only four intermolecular C—H···O interactions with H···O ≤ 2.70 Å and C—H···O > 100° (Table 1) and the molecules are therefore held together mainly by van der Waals interactions.