organic compounds
(4bS,8aS)-1-Isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octahydrophenanthren-2-yl acetate
aLaboratoire de Synthése Organique et Physico-Chimie Moléculaire, Département de Chimie, Faculté des Sciences, Semlalia, BP 2390, Marrakech 40000, Morocco, and bLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France
*Correspondence e-mail: itto35@hotmail.com
The hemisynthesis of the title compound, C22H32O2, was carried out through direct acetylation reaction of the naturally occurring diterpene totarol [systematic name: (4bS,8aS)-4b,8,8-trimethyl-1-propan-2-yl-5,6,7,8a,9,10-hexahydrophenanthren-2-ol]. The molecule is built up from three fused six membered rings, one saturated and two unsaturated. The central unsaturated ring has a half-chair conformation, whereas the other unsaturated ring displays a chair conformation. The is deduced from the chemical pathway. The value of the Hooft parameter [−0.10 (6)] allowed this to be confirmed.
Related literature
For the synthesis, see: Short & Stromberg (1937). For biological properties of totarol, see: Barrero et al. (2003); Bernabeu et al. (2002); Haraguchi et al. (1996); Marcos et al. (2003); Tacon et al. (2012). For related structures, see: Zeroual et al. (2008); Pettit et al. (2004). For structural discussion, see: Cremer & Pople (1975); Flack (1983); Flack & Bernardinelli (2000); Spek (2009).
Experimental
Crystal data
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Data collection: CrysAlis PRO (Agilent, 2012); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL2013.
Supporting information
10.1107/S1600536814002748/xu5767sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536814002748/xu5767Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536814002748/xu5767Isup3.cml
A solution of totarol (1) (90 mg, 0.314 mmol) in acetic anhydride (20 ml) and pyridine (20 ml) was heated under reflux for 24 h. After cooling, the mixture was acidified with 1N HCl solution then extracted with ether (3 × 20 ml). The organic layer was washed with water, dried on anhydrous Na2SO4 and then evaporated under reduced pressure. The obtained residue was chromatographied on silica gel column using hexane and ethyl acetate (97/3) as
to give (4bS,8aS)-1-isopropyl-4 b,8,8-trimethyl-4 b,5,6,7,8,8a,9,10-octahydrophenanthren-2-yl acetate (2) (100 mg) in 97% yield.All H atoms attached to C atoms were fixed geometrically and treated as riding with C—H = 0.99 Å (methylene), 0.98 Å (methyl), 1.0 Å (methine) with Uiso(H) = 1.2Ueq(CH and CH2) or Uiso(H) = 1.5Ueq(CH3).
Although the standard deviation on the Flack's parameter, 0.0 (3), is rather high, the value of the Hooft's parameter, -0.10 (6), is more reliable and allows to confirm the
It is interesting to point out that inverting the configuration gives values of Hooft and close to 1.0 with similar standard deviation.Data collection: CrysAlis PRO (Agilent, 2012); cell
CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: ORTEPIII (Burnett & Johnson, 1996) ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL2013 (Sheldrick, 2008).Fig. 1. : Molecular view of compound (2) with the atom labeling scheme. Ellipsoids are drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii. |
C22H32O2 | F(000) = 360 |
Mr = 328.47 | Dx = 1.151 Mg m−3 |
Monoclinic, P21 | Cu Kα radiation, λ = 1.54184 Å |
a = 7.4250 (2) Å | Cell parameters from 3311 reflections |
b = 10.5716 (3) Å | θ = 3.7–60.6° |
c = 12.0747 (3) Å | µ = 0.55 mm−1 |
β = 90.124 (2)° | T = 180 K |
V = 947.79 (4) Å3 | Box, colourless |
Z = 2 | 0.38 × 0.38 × 0.14 mm |
Agilent Xcalibur (Eos, Gemini ultra) diffractometer | 2511 independent reflections |
Radiation source: Enhance Ultra (Cu) X-ray Source | 2490 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.012 |
Detector resolution: 16.1978 pixels mm-1 | θmax = 60.7°, θmin = 3.7° |
ω scans | h = −7→8 |
Absorption correction: multi-scan Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm (CrysAlis PRO, Agilent, 2012) | k = −11→11 |
Tmin = 0.860, Tmax = 1.000 | l = −13→13 |
4370 measured reflections |
Refinement on F2 | H-atom parameters constrained |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0433P)2 + 0.168P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.029 | (Δ/σ)max < 0.001 |
wR(F2) = 0.075 | Δρmax = 0.13 e Å−3 |
S = 1.04 | Δρmin = −0.14 e Å−3 |
2511 reflections | Extinction correction: SHELXL2013 (Sheldrick, 2013), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
225 parameters | Extinction coefficient: 0.050 (2) |
1 restraint | Absolute structure: Refined as an inversion twin. |
Hydrogen site location: inferred from neighbouring sites | Absolute structure parameter: 0.0 (3) |
C22H32O2 | V = 947.79 (4) Å3 |
Mr = 328.47 | Z = 2 |
Monoclinic, P21 | Cu Kα radiation |
a = 7.4250 (2) Å | µ = 0.55 mm−1 |
b = 10.5716 (3) Å | T = 180 K |
c = 12.0747 (3) Å | 0.38 × 0.38 × 0.14 mm |
β = 90.124 (2)° |
Agilent Xcalibur (Eos, Gemini ultra) diffractometer | 2511 independent reflections |
Absorption correction: multi-scan Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm (CrysAlis PRO, Agilent, 2012) | 2490 reflections with I > 2σ(I) |
Tmin = 0.860, Tmax = 1.000 | Rint = 0.012 |
4370 measured reflections | θmax = 60.7° |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters constrained |
wR(F2) = 0.075 | Δρmax = 0.13 e Å−3 |
S = 1.04 | Δρmin = −0.14 e Å−3 |
2511 reflections | Absolute structure: Refined as an inversion twin. |
225 parameters | Absolute structure parameter: 0.0 (3) |
1 restraint |
Experimental. Absorption correction: Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm (CrysAlis PRO; Agilent Technologies, 2012) |
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. Refined as a 2-component inversion twin. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.6487 (3) | 0.6992 (2) | 0.17276 (16) | 0.0270 (5) | |
C2 | 0.4780 (3) | 0.7203 (2) | 0.13012 (17) | 0.0283 (5) | |
C3 | 0.3461 (3) | 0.7823 (2) | 0.18816 (19) | 0.0334 (5) | |
H3 | 0.2304 | 0.7948 | 0.1562 | 0.040* | |
C4 | 0.3833 (3) | 0.8262 (2) | 0.29347 (18) | 0.0319 (5) | |
H4 | 0.2916 | 0.8682 | 0.3341 | 0.038* | |
C4A | 0.5533 (3) | 0.81000 (19) | 0.34131 (17) | 0.0244 (5) | |
C4B | 0.5942 (3) | 0.8675 (2) | 0.45589 (18) | 0.0258 (5) | |
C5 | 0.4239 (3) | 0.8711 (3) | 0.52884 (19) | 0.0346 (6) | |
H5A | 0.3376 | 0.9327 | 0.4972 | 0.041* | |
H5B | 0.3659 | 0.7868 | 0.5276 | 0.041* | |
C6 | 0.4646 (3) | 0.9074 (3) | 0.6486 (2) | 0.0406 (6) | |
H6A | 0.5144 | 0.9942 | 0.6509 | 0.049* | |
H6B | 0.3515 | 0.9067 | 0.6919 | 0.049* | |
C7 | 0.5980 (3) | 0.8167 (3) | 0.70024 (18) | 0.0371 (6) | |
H7A | 0.5427 | 0.7315 | 0.7033 | 0.045* | |
H7B | 0.6222 | 0.8438 | 0.7773 | 0.045* | |
C8 | 0.7773 (3) | 0.8075 (2) | 0.63830 (18) | 0.0338 (5) | |
C8A | 0.7386 (3) | 0.7834 (2) | 0.51303 (17) | 0.0275 (5) | |
H8A | 0.6896 | 0.6954 | 0.5093 | 0.033* | |
C9 | 0.9073 (3) | 0.7813 (3) | 0.44192 (19) | 0.0372 (6) | |
H9A | 0.9521 | 0.8687 | 0.4322 | 0.045* | |
H9B | 1.0022 | 0.7319 | 0.4801 | 0.045* | |
C10 | 0.8707 (3) | 0.7233 (3) | 0.32926 (18) | 0.0366 (6) | |
H10A | 0.9617 | 0.7561 | 0.2768 | 0.044* | |
H10B | 0.8890 | 0.6307 | 0.3351 | 0.044* | |
C10A | 0.6862 (3) | 0.74630 (19) | 0.28005 (17) | 0.0261 (5) | |
C11 | 0.7945 (3) | 0.6336 (2) | 0.10479 (18) | 0.0343 (6) | |
H11 | 0.8978 | 0.6181 | 0.1562 | 0.041* | |
C12 | 0.7413 (4) | 0.5048 (3) | 0.0572 (2) | 0.0540 (8) | |
H12A | 0.8501 | 0.4562 | 0.0400 | 0.081* | |
H12B | 0.6704 | 0.5170 | −0.0105 | 0.081* | |
H12C | 0.6691 | 0.4585 | 0.1117 | 0.081* | |
C13 | 0.8634 (4) | 0.7225 (3) | 0.0150 (2) | 0.0518 (7) | |
H13A | 0.9103 | 0.7998 | 0.0492 | 0.078* | |
H13B | 0.7644 | 0.7440 | −0.0355 | 0.078* | |
H13C | 0.9597 | 0.6807 | −0.0266 | 0.078* | |
C14 | 0.6541 (4) | 1.0050 (2) | 0.4337 (2) | 0.0433 (6) | |
H14A | 0.5590 | 1.0497 | 0.3933 | 0.065* | |
H14B | 0.7647 | 1.0047 | 0.3895 | 0.065* | |
H14C | 0.6768 | 1.0478 | 0.5044 | 0.065* | |
C15 | 0.8902 (4) | 0.9257 (3) | 0.6616 (2) | 0.0489 (7) | |
H15A | 0.9251 | 0.9270 | 0.7399 | 0.073* | |
H15B | 0.8193 | 1.0013 | 0.6444 | 0.073* | |
H15C | 0.9986 | 0.9243 | 0.6154 | 0.073* | |
C16 | 0.8803 (4) | 0.6933 (3) | 0.6843 (2) | 0.0561 (8) | |
H16A | 0.8152 | 0.6154 | 0.6657 | 0.084* | |
H16B | 0.8905 | 0.7008 | 0.7649 | 0.084* | |
H16C | 1.0009 | 0.6905 | 0.6516 | 0.084* | |
C17 | 0.3222 (3) | 0.5899 (2) | 0.00169 (19) | 0.0345 (6) | |
C18 | 0.3010 (4) | 0.5659 (3) | −0.1197 (2) | 0.0460 (7) | |
H18A | 0.1878 | 0.5206 | −0.1331 | 0.069* | |
H18B | 0.4021 | 0.5146 | −0.1461 | 0.069* | |
H18C | 0.2991 | 0.6467 | −0.1594 | 0.069* | |
O1 | 0.4419 (2) | 0.68523 (16) | 0.01943 (11) | 0.0338 (4) | |
O2 | 0.2470 (2) | 0.53449 (19) | 0.07423 (14) | 0.0491 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0302 (12) | 0.0261 (11) | 0.0248 (11) | 0.0012 (10) | 0.0028 (9) | 0.0023 (9) |
C2 | 0.0305 (12) | 0.0316 (12) | 0.0230 (10) | −0.0026 (10) | 0.0004 (9) | 0.0014 (9) |
C3 | 0.0244 (12) | 0.0444 (13) | 0.0315 (12) | 0.0021 (11) | −0.0022 (9) | 0.0002 (10) |
C4 | 0.0269 (12) | 0.0355 (12) | 0.0333 (12) | 0.0060 (10) | 0.0031 (9) | −0.0010 (10) |
C4A | 0.0256 (11) | 0.0205 (10) | 0.0271 (11) | 0.0010 (9) | 0.0026 (8) | 0.0024 (9) |
C4B | 0.0262 (11) | 0.0221 (10) | 0.0290 (11) | 0.0006 (9) | 0.0022 (9) | −0.0022 (9) |
C5 | 0.0302 (12) | 0.0422 (13) | 0.0314 (12) | 0.0063 (11) | 0.0022 (10) | −0.0072 (10) |
C6 | 0.0327 (13) | 0.0533 (17) | 0.0357 (13) | 0.0027 (12) | 0.0065 (10) | −0.0129 (12) |
C7 | 0.0413 (14) | 0.0448 (14) | 0.0253 (11) | −0.0082 (12) | 0.0023 (10) | −0.0068 (11) |
C8 | 0.0342 (12) | 0.0386 (13) | 0.0286 (11) | 0.0002 (11) | −0.0037 (9) | −0.0071 (10) |
C8A | 0.0269 (11) | 0.0271 (11) | 0.0286 (11) | −0.0019 (10) | −0.0001 (9) | −0.0041 (9) |
C9 | 0.0276 (12) | 0.0497 (14) | 0.0343 (13) | 0.0040 (11) | −0.0011 (9) | −0.0077 (11) |
C10 | 0.0280 (12) | 0.0513 (15) | 0.0305 (12) | 0.0089 (11) | 0.0005 (10) | −0.0047 (11) |
C10A | 0.0261 (11) | 0.0259 (11) | 0.0263 (11) | 0.0000 (9) | 0.0031 (9) | 0.0028 (9) |
C11 | 0.0322 (12) | 0.0457 (14) | 0.0251 (11) | 0.0109 (11) | 0.0018 (9) | −0.0012 (10) |
C12 | 0.0587 (19) | 0.0487 (17) | 0.0546 (17) | 0.0163 (14) | 0.0060 (14) | −0.0166 (13) |
C13 | 0.0399 (15) | 0.0696 (19) | 0.0460 (15) | 0.0121 (14) | 0.0175 (12) | 0.0119 (14) |
C14 | 0.0599 (17) | 0.0281 (13) | 0.0421 (14) | −0.0045 (12) | −0.0035 (12) | 0.0017 (11) |
C15 | 0.0363 (14) | 0.0662 (18) | 0.0441 (15) | −0.0116 (13) | −0.0023 (11) | −0.0189 (14) |
C16 | 0.068 (2) | 0.0664 (18) | 0.0338 (13) | 0.0231 (17) | −0.0133 (13) | −0.0045 (14) |
C17 | 0.0352 (13) | 0.0364 (13) | 0.0319 (12) | 0.0016 (11) | −0.0017 (10) | −0.0013 (10) |
C18 | 0.0489 (16) | 0.0560 (17) | 0.0332 (13) | −0.0039 (13) | −0.0023 (11) | −0.0089 (12) |
O1 | 0.0341 (9) | 0.0432 (9) | 0.0239 (8) | −0.0036 (8) | −0.0002 (6) | −0.0011 (7) |
O2 | 0.0587 (12) | 0.0514 (11) | 0.0372 (9) | −0.0160 (10) | 0.0039 (9) | −0.0001 (9) |
C1—C2 | 1.385 (3) | C9—H9A | 0.9900 |
C1—C10A | 1.415 (3) | C9—H9B | 0.9900 |
C1—C11 | 1.526 (3) | C10—C10A | 1.512 (3) |
C2—C3 | 1.372 (3) | C10—H10A | 0.9900 |
C2—O1 | 1.412 (3) | C10—H10B | 0.9900 |
C3—C4 | 1.381 (3) | C11—C13 | 1.524 (4) |
C3—H3 | 0.9500 | C11—C12 | 1.530 (4) |
C4—C4A | 1.398 (3) | C11—H11 | 1.0000 |
C4—H4 | 0.9500 | C12—H12A | 0.9800 |
C4A—C10A | 1.406 (3) | C12—H12B | 0.9800 |
C4A—C4B | 1.541 (3) | C12—H12C | 0.9800 |
C4B—C5 | 1.543 (3) | C13—H13A | 0.9800 |
C4B—C14 | 1.544 (3) | C13—H13B | 0.9800 |
C4B—C8A | 1.553 (3) | C13—H13C | 0.9800 |
C5—C6 | 1.526 (3) | C14—H14A | 0.9800 |
C5—H5A | 0.9900 | C14—H14B | 0.9800 |
C5—H5B | 0.9900 | C14—H14C | 0.9800 |
C6—C7 | 1.512 (4) | C15—H15A | 0.9800 |
C6—H6A | 0.9900 | C15—H15B | 0.9800 |
C6—H6B | 0.9900 | C15—H15C | 0.9800 |
C7—C8 | 1.532 (3) | C16—H16A | 0.9800 |
C7—H7A | 0.9900 | C16—H16B | 0.9800 |
C7—H7B | 0.9900 | C16—H16C | 0.9800 |
C8—C15 | 1.530 (4) | C17—O2 | 1.193 (3) |
C8—C16 | 1.533 (4) | C17—O1 | 1.361 (3) |
C8—C8A | 1.560 (3) | C17—C18 | 1.496 (3) |
C8A—C9 | 1.520 (3) | C18—H18A | 0.9800 |
C8A—H8A | 1.0000 | C18—H18B | 0.9800 |
C9—C10 | 1.516 (3) | C18—H18C | 0.9800 |
C2—C1—C10A | 117.49 (18) | H9A—C9—H9B | 108.0 |
C2—C1—C11 | 121.51 (18) | C10A—C10—C9 | 116.61 (19) |
C10A—C1—C11 | 120.92 (19) | C10A—C10—H10A | 108.1 |
C3—C2—C1 | 122.74 (18) | C9—C10—H10A | 108.1 |
C3—C2—O1 | 118.32 (18) | C10A—C10—H10B | 108.1 |
C1—C2—O1 | 118.77 (18) | C9—C10—H10B | 108.1 |
C2—C3—C4 | 119.29 (19) | H10A—C10—H10B | 107.3 |
C2—C3—H3 | 120.4 | C4A—C10A—C1 | 120.89 (19) |
C4—C3—H3 | 120.4 | C4A—C10A—C10 | 120.43 (18) |
C3—C4—C4A | 121.18 (19) | C1—C10A—C10 | 118.65 (18) |
C3—C4—H4 | 119.4 | C13—C11—C1 | 110.0 (2) |
C4A—C4—H4 | 119.4 | C13—C11—C12 | 111.6 (2) |
C4—C4A—C10A | 118.38 (18) | C1—C11—C12 | 115.1 (2) |
C4—C4A—C4B | 119.92 (18) | C13—C11—H11 | 106.5 |
C10A—C4A—C4B | 121.63 (18) | C1—C11—H11 | 106.5 |
C4A—C4B—C5 | 111.23 (17) | C12—C11—H11 | 106.5 |
C4A—C4B—C14 | 105.79 (18) | C11—C12—H12A | 109.5 |
C5—C4B—C14 | 108.22 (19) | C11—C12—H12B | 109.5 |
C4A—C4B—C8A | 107.92 (17) | H12A—C12—H12B | 109.5 |
C5—C4B—C8A | 109.04 (17) | C11—C12—H12C | 109.5 |
C14—C4B—C8A | 114.6 (2) | H12A—C12—H12C | 109.5 |
C6—C5—C4B | 112.74 (18) | H12B—C12—H12C | 109.5 |
C6—C5—H5A | 109.0 | C11—C13—H13A | 109.5 |
C4B—C5—H5A | 109.0 | C11—C13—H13B | 109.5 |
C6—C5—H5B | 109.0 | H13A—C13—H13B | 109.5 |
C4B—C5—H5B | 109.0 | C11—C13—H13C | 109.5 |
H5A—C5—H5B | 107.8 | H13A—C13—H13C | 109.5 |
C7—C6—C5 | 111.0 (2) | H13B—C13—H13C | 109.5 |
C7—C6—H6A | 109.4 | C4B—C14—H14A | 109.5 |
C5—C6—H6A | 109.4 | C4B—C14—H14B | 109.5 |
C7—C6—H6B | 109.4 | H14A—C14—H14B | 109.5 |
C5—C6—H6B | 109.4 | C4B—C14—H14C | 109.5 |
H6A—C6—H6B | 108.0 | H14A—C14—H14C | 109.5 |
C6—C7—C8 | 114.08 (19) | H14B—C14—H14C | 109.5 |
C6—C7—H7A | 108.7 | C8—C15—H15A | 109.5 |
C8—C7—H7A | 108.7 | C8—C15—H15B | 109.5 |
C6—C7—H7B | 108.7 | H15A—C15—H15B | 109.5 |
C8—C7—H7B | 108.7 | C8—C15—H15C | 109.5 |
H7A—C7—H7B | 107.6 | H15A—C15—H15C | 109.5 |
C15—C8—C7 | 109.6 (2) | H15B—C15—H15C | 109.5 |
C15—C8—C16 | 107.7 (2) | C8—C16—H16A | 109.5 |
C7—C8—C16 | 107.9 (2) | C8—C16—H16B | 109.5 |
C15—C8—C8A | 114.3 (2) | H16A—C16—H16B | 109.5 |
C7—C8—C8A | 109.00 (17) | C8—C16—H16C | 109.5 |
C16—C8—C8A | 108.25 (19) | H16A—C16—H16C | 109.5 |
C9—C8A—C4B | 109.05 (18) | H16B—C16—H16C | 109.5 |
C9—C8A—C8 | 113.59 (17) | O2—C17—O1 | 123.7 (2) |
C4B—C8A—C8 | 117.57 (17) | O2—C17—C18 | 126.0 (2) |
C9—C8A—H8A | 105.2 | O1—C17—C18 | 110.3 (2) |
C4B—C8A—H8A | 105.2 | C17—C18—H18A | 109.5 |
C8—C8A—H8A | 105.2 | C17—C18—H18B | 109.5 |
C10—C9—C8A | 111.51 (18) | H18A—C18—H18B | 109.5 |
C10—C9—H9A | 109.3 | C17—C18—H18C | 109.5 |
C8A—C9—H9A | 109.3 | H18A—C18—H18C | 109.5 |
C10—C9—H9B | 109.3 | H18B—C18—H18C | 109.5 |
C8A—C9—H9B | 109.3 | C17—O1—C2 | 117.79 (16) |
Experimental details
Crystal data | |
Chemical formula | C22H32O2 |
Mr | 328.47 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 180 |
a, b, c (Å) | 7.4250 (2), 10.5716 (3), 12.0747 (3) |
β (°) | 90.124 (2) |
V (Å3) | 947.79 (4) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 0.55 |
Crystal size (mm) | 0.38 × 0.38 × 0.14 |
Data collection | |
Diffractometer | Agilent Xcalibur (Eos, Gemini ultra) diffractometer |
Absorption correction | Multi-scan Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm (CrysAlis PRO, Agilent, 2012) |
Tmin, Tmax | 0.860, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4370, 2511, 2490 |
Rint | 0.012 |
θmax (°) | 60.7 |
(sin θ/λ)max (Å−1) | 0.566 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.075, 1.04 |
No. of reflections | 2511 |
No. of parameters | 225 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.14 |
Absolute structure | Refined as an inversion twin. |
Absolute structure parameter | 0.0 (3) |
Computer programs: CrysAlis PRO (Agilent, 2012), SIR97 (Altomare et al., 1999), SHELXL2013 (Sheldrick, 2008), ORTEPIII (Burnett & Johnson, 1996) ORTEP-3 for Windows (Farrugia, 2012).
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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.
The hemisynthesis of the title compound C22H32O2 2 was carried out through direct acetylation reaction of naturally occurred Totarol (1). Totarol (1) is a naturally produced diterpene isolated from a several plants such as Podocarpus totara (Short & Stromberg, 1937) Tetraclinis articulata (Barrero et al., 2003). It has been attracting great interest because of its biological properties ranging from Antimicrobial (Haraguchi et al., 1996), anti-oxidant (Bernabeu et al., 2002), Anti-inflammatory, analgesic, anti-tumoral (Marcos et al., 2003) to Anti-plasmodial (Tacon et al., 2012).
In the aim of preparing totarol derivatives, we report here, the hemisynthesis of (4bS,8aS)-1-isopropyl-4 b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octahydrophenanthren-2-yl acetate 2 from naturally occurred Totarol (1). Thus, treatment of (1) with acetic anhydride in pyridine provides (2) as colorless crystals in 97% yield. Its structure was fully characterized by its mass and NMR spectroscopic data. Furthermore, an X-ray single-crystal structure analysis allowed us to confirm unambiguously its full structure.
Compound (2) is built up from three fused six membered rings, a saturated one and two unsaturated (Fig. 1). The central unsaturated ring has an half chair conformation with puckering parameters: Q = 0.531 (2) Å, θ= 50.4 (2)° and φ= 120.1 (4)° (Cremer & Pople, 1975), whereas the second insaturated six-membered ring displays a chair conformation with puckering parameters: Q = 0.535 (3) Å, θ= 173.2 (3) (2)° and φ= 289 (2)°. Similar conformation for the three fused rings has been reported previously with hydroxyl substituent in place of the acetate in the title compound (Zeroual et al., 2008) and with either an hydroxyl or a methoxy substituent on the central ring (Pettit et al., 2004).
The absolute configuration (4S,8S) deduced from the chemical pathway is supported by the refinement of the Flack parameter, 0.0 (3), (Flack, 1983; Flack & Bernardinelli, 2000) and confirmed by the refinement of the Hooft parameter, -0.10 (6) (Spek, 2009).