Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100004790/da1124sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100004790/da1124IIIsup2.hkl |
CCDC reference: 147660
The title compound has been prepared from both compounds (I) and (II) under the same conditions. Its synthesis and spectroscopic characterization has been reported recently (Demuner et al., 1998). Suitable single crystals of the title compound were obtained by slow evaporation of a THF/ethanol (1:10) solution. The absolute structure could not be determined.
H atoms were positioned geometrically and a riding model was used during the refinement process, with Uiso set to 1.5 (for methyl-H atoms) or 1.2 (for the remaining) times the value of Ueq of the atom to which they are attached.
Data collection: CAD-4 Software (Enraf Nonius, 1989); cell refinement: CAD-4 Software; data reduction: SDP (Fair, 1990); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.
Fig. 1. An ORTEPIII view (Burnett & Johnson, 1996) of the title compound showing 40% probability displacement ellipsoids. |
C20H25FO3 | F(000) = 356 |
Mr = 332.40 | Dx = 1.309 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 9.440 (1) Å | Cell parameters from 25 reflections |
b = 9.366 (1) Å | θ = 10.3–18.3° |
c = 9.741 (1) Å | µ = 0.09 mm−1 |
β = 101.69 (1)° | T = 293 K |
V = 843.4 (2) Å3 | Plate, colourless |
Z = 2 | 0.45 × 0.40 × 0.08 mm |
Enraf-Nonius CAD-4 diffractometer | 1571 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.031 |
Graphite monochromator | θmax = 26.3°, θmin = 2.7° |
ω/2θ scans | h = 0→11 |
Absorption correction: ψ scan (North et al., 1968) | k = −11→0 |
Tmin = 0.961, Tmax = 0.993 | l = −12→11 |
1920 measured reflections | 3 standard reflections every 120 min |
1813 independent reflections | intensity decay: 1% |
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)] = 0.035 | H-atom parameters constrained |
wR(F2) = 0.097 | Calculated w = 1/[σ2(Fo2) + (0.0491P)2 + 0.1231P] where P = (Fo2 + 2Fc2)/3 |
S = 1.11 | (Δ/σ)max < 0.001 |
1813 reflections | Δρmax = 0.14 e Å−3 |
218 parameters | Δρmin = −0.19 e Å−3 |
1 restraint | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.6 (12) |
C20H25FO3 | V = 843.4 (2) Å3 |
Mr = 332.40 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 9.440 (1) Å | µ = 0.09 mm−1 |
b = 9.366 (1) Å | T = 293 K |
c = 9.741 (1) Å | 0.45 × 0.40 × 0.08 mm |
β = 101.69 (1)° |
Enraf-Nonius CAD-4 diffractometer | 1571 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.031 |
Tmin = 0.961, Tmax = 0.993 | 3 standard reflections every 120 min |
1920 measured reflections | intensity decay: 1% |
1813 independent reflections |
R[F2 > 2σ(F2)] = 0.035 | H-atom parameters constrained |
wR(F2) = 0.097 | Δρmax = 0.14 e Å−3 |
S = 1.11 | Δρmin = −0.19 e Å−3 |
1813 reflections | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
218 parameters | Absolute structure parameter: −0.6 (12) |
1 restraint |
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 | ||
F | 0.90740 (17) | 0.2733 (2) | 0.65624 (19) | 0.0620 (5) | |
O1 | 0.8964 (2) | −0.3908 (2) | 0.7621 (2) | 0.0574 (6) | |
O2 | 0.7468 (2) | 0.0673 (3) | 0.9568 (2) | 0.0634 (6) | |
O3 | 0.8758 (2) | 0.2340 (2) | 0.8779 (2) | 0.0552 (5) | |
C1 | 1.3326 (3) | −0.0233 (3) | 0.5930 (3) | 0.0474 (6) | |
H11 | 1.2616 | −0.0167 | 0.5060 | 0.057* | |
H12 | 1.3728 | −0.1190 | 0.5998 | 0.057* | |
C2 | 1.4535 (3) | 0.0857 (4) | 0.5916 (3) | 0.0546 (7) | |
H21 | 1.5288 | 0.0725 | 0.6745 | 0.066* | |
H22 | 1.4956 | 0.0691 | 0.5101 | 0.066* | |
C3 | 1.3974 (3) | 0.2385 (3) | 0.5882 (3) | 0.0523 (7) | |
H31 | 1.3318 | 0.2538 | 0.4990 | 0.063* | |
H32 | 1.4786 | 0.3028 | 0.5921 | 0.063* | |
C4 | 1.3186 (3) | 0.2792 (3) | 0.7064 (3) | 0.0413 (6) | |
C5 | 1.2049 (3) | 0.1618 (3) | 0.7090 (2) | 0.0336 (5) | |
H51 | 1.1390 | 0.1690 | 0.6175 | 0.040* | |
C6 | 1.1046 (3) | 0.1656 (3) | 0.8168 (2) | 0.0350 (5) | |
H61 | 1.1649 | 0.1832 | 0.9096 | 0.042* | |
C8 | 1.0472 (2) | 0.0123 (3) | 0.8146 (2) | 0.0335 (5) | |
H81 | 1.0831 | −0.0300 | 0.9071 | 0.040* | |
C9 | 1.1124 (3) | −0.0711 (3) | 0.7075 (2) | 0.0357 (5) | |
H91 | 1.0538 | −0.0493 | 0.6148 | 0.043* | |
C10 | 1.2590 (2) | 0.0040 (3) | 0.7170 (2) | 0.0355 (5) | |
C11 | 1.0972 (3) | −0.2314 (3) | 0.7314 (3) | 0.0477 (6) | |
H111 | 1.1096 | −0.2847 | 0.6493 | 0.057* | |
H112 | 1.1697 | −0.2630 | 0.8110 | 0.057* | |
C12 | 0.9489 (3) | −0.2542 (3) | 0.7589 (3) | 0.0447 (6) | |
C13 | 0.8498 (3) | −0.1591 (3) | 0.7835 (3) | 0.0409 (6) | |
C14 | 0.8819 (2) | −0.0014 (3) | 0.7811 (3) | 0.0373 (5) | |
H141 | 0.8466 | 0.0336 | 0.6855 | 0.045* | |
C15 | 0.7268 (3) | −0.2401 (4) | 0.8025 (3) | 0.0485 (7) | |
H151 | 0.6405 | −0.2044 | 0.8206 | 0.058* | |
C16 | 0.7606 (4) | −0.3776 (4) | 0.7893 (3) | 0.0565 (8) | |
H161 | 0.6998 | −0.4538 | 0.7976 | 0.068* | |
C17 | 0.8255 (3) | 0.0949 (3) | 0.8791 (3) | 0.0458 (6) | |
C18 | 1.2420 (4) | 0.4220 (4) | 0.6681 (4) | 0.0596 (8) | |
H181 | 1.3115 | 0.4925 | 0.6541 | 0.089* | |
H182 | 1.1961 | 0.4518 | 0.7427 | 0.089* | |
H183 | 1.1703 | 0.4112 | 0.5834 | 0.089* | |
C19 | 1.4264 (3) | 0.3014 (4) | 0.8455 (3) | 0.0549 (7) | |
H191 | 1.4836 | 0.3850 | 0.8390 | 0.082* | |
H192 | 1.4886 | 0.2197 | 0.8646 | 0.082* | |
H193 | 1.3745 | 0.3135 | 0.9199 | 0.082* | |
C20 | 1.3605 (3) | −0.0374 (3) | 0.8550 (3) | 0.0483 (7) | |
H201 | 1.3228 | −0.0008 | 0.9325 | 0.072* | |
H202 | 1.4548 | 0.0022 | 0.8573 | 0.072* | |
H203 | 1.3675 | −0.1395 | 0.8617 | 0.072* | |
C21 | 0.9790 (3) | 0.2700 (3) | 0.7957 (3) | 0.0474 (6) | |
H211 | 1.0169 | 0.3656 | 0.8226 | 0.057* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F | 0.0583 (10) | 0.0536 (11) | 0.0704 (10) | 0.0184 (9) | 0.0041 (8) | 0.0180 (9) |
O1 | 0.0713 (15) | 0.0360 (12) | 0.0676 (13) | −0.0094 (10) | 0.0203 (11) | 0.0007 (9) |
O2 | 0.0562 (12) | 0.0694 (16) | 0.0733 (14) | −0.0052 (11) | 0.0341 (10) | −0.0162 (12) |
O3 | 0.0521 (11) | 0.0424 (11) | 0.0768 (14) | 0.0061 (9) | 0.0265 (10) | −0.0139 (10) |
C1 | 0.0484 (14) | 0.0462 (16) | 0.0520 (15) | 0.0017 (13) | 0.0205 (11) | −0.0066 (13) |
C2 | 0.0578 (17) | 0.0576 (18) | 0.0563 (16) | −0.0043 (15) | 0.0302 (13) | −0.0097 (15) |
C3 | 0.0607 (17) | 0.0528 (18) | 0.0484 (15) | −0.0126 (14) | 0.0226 (13) | −0.0025 (13) |
C4 | 0.0485 (13) | 0.0370 (14) | 0.0410 (12) | −0.0040 (12) | 0.0150 (10) | −0.0025 (11) |
C5 | 0.0371 (12) | 0.0322 (12) | 0.0309 (11) | 0.0015 (10) | 0.0055 (9) | −0.0008 (10) |
C6 | 0.0386 (12) | 0.0327 (12) | 0.0334 (11) | 0.0039 (10) | 0.0063 (9) | −0.0001 (10) |
C8 | 0.0353 (11) | 0.0332 (12) | 0.0313 (10) | 0.0055 (10) | 0.0049 (9) | 0.0004 (9) |
C9 | 0.0381 (12) | 0.0313 (13) | 0.0382 (12) | 0.0055 (10) | 0.0089 (10) | 0.0008 (10) |
C10 | 0.0394 (12) | 0.0349 (13) | 0.0332 (11) | 0.0077 (11) | 0.0100 (9) | 0.0010 (10) |
C11 | 0.0498 (14) | 0.0315 (14) | 0.0648 (16) | 0.0057 (12) | 0.0186 (12) | −0.0007 (13) |
C12 | 0.0536 (15) | 0.0293 (14) | 0.0509 (15) | −0.0039 (11) | 0.0102 (12) | 0.0011 (11) |
C13 | 0.0419 (13) | 0.0413 (15) | 0.0383 (13) | −0.0013 (11) | 0.0057 (10) | −0.0019 (11) |
C14 | 0.0361 (12) | 0.0362 (14) | 0.0384 (12) | 0.0031 (10) | 0.0048 (9) | 0.0002 (11) |
C15 | 0.0479 (14) | 0.0551 (18) | 0.0428 (13) | −0.0101 (13) | 0.0098 (11) | −0.0010 (13) |
C16 | 0.0637 (19) | 0.056 (2) | 0.0518 (15) | −0.0189 (15) | 0.0167 (14) | 0.0010 (14) |
C17 | 0.0353 (12) | 0.0496 (17) | 0.0527 (14) | 0.0060 (12) | 0.0091 (11) | −0.0072 (13) |
C18 | 0.071 (2) | 0.0365 (16) | 0.074 (2) | −0.0020 (15) | 0.0216 (16) | 0.0073 (15) |
C19 | 0.0509 (15) | 0.061 (2) | 0.0534 (15) | −0.0170 (15) | 0.0117 (12) | −0.0140 (14) |
C20 | 0.0361 (12) | 0.0551 (17) | 0.0530 (14) | 0.0100 (12) | 0.0071 (10) | 0.0110 (13) |
C21 | 0.0488 (14) | 0.0342 (14) | 0.0605 (16) | 0.0059 (13) | 0.0142 (12) | −0.0015 (13) |
F—C21 | 1.390 (3) | C5—C10 | 1.560 (3) |
O1—C16 | 1.366 (4) | C6—C21 | 1.518 (3) |
O1—C12 | 1.375 (3) | C6—C8 | 1.533 (4) |
O2—C17 | 1.192 (3) | C8—C9 | 1.528 (3) |
O3—C17 | 1.387 (4) | C8—C14 | 1.533 (3) |
O3—C21 | 1.421 (3) | C9—C11 | 1.531 (4) |
C1—C10 | 1.532 (3) | C9—C10 | 1.539 (3) |
C1—C2 | 1.533 (4) | C10—C20 | 1.535 (3) |
C2—C3 | 1.524 (5) | C11—C12 | 1.493 (4) |
C3—C4 | 1.540 (3) | C12—C13 | 1.347 (4) |
C4—C18 | 1.530 (4) | C13—C15 | 1.430 (4) |
C4—C19 | 1.536 (4) | C13—C14 | 1.509 (4) |
C4—C5 | 1.540 (4) | C14—C17 | 1.488 (4) |
C5—C6 | 1.550 (3) | C15—C16 | 1.338 (5) |
C16—O1—C12 | 106.1 (2) | C1—C10—C9 | 115.0 (2) |
C17—O3—C21 | 120.2 (2) | C20—C10—C9 | 109.3 (2) |
C10—C1—C2 | 110.6 (2) | C1—C10—C5 | 108.4 (2) |
C3—C2—C1 | 111.7 (2) | C20—C10—C5 | 115.0 (2) |
C2—C3—C4 | 115.8 (2) | C9—C10—C5 | 98.53 (18) |
C18—C4—C19 | 107.0 (2) | C12—C11—C9 | 106.7 (2) |
C18—C4—C3 | 108.1 (2) | C13—C12—O1 | 110.2 (2) |
C19—C4—C3 | 111.0 (2) | C13—C12—C11 | 130.3 (3) |
C18—C4—C5 | 109.4 (2) | O1—C12—C11 | 119.5 (2) |
C19—C4—C5 | 114.9 (2) | C12—C13—C15 | 106.4 (3) |
C3—C4—C5 | 106.2 (2) | C12—C13—C14 | 119.7 (2) |
C4—C5—C6 | 121.2 (2) | C15—C13—C14 | 133.8 (3) |
C4—C5—C10 | 117.0 (2) | C17—C14—C13 | 119.0 (2) |
C6—C5—C10 | 103.10 (19) | C17—C14—C8 | 107.1 (2) |
C21—C6—C8 | 109.7 (2) | C13—C14—C8 | 106.1 (2) |
C21—C6—C5 | 119.4 (2) | C16—C15—C13 | 106.4 (3) |
C8—C6—C5 | 103.42 (19) | C15—C16—O1 | 110.9 (3) |
C9—C8—C14 | 110.21 (19) | O2—C17—O3 | 117.9 (3) |
C9—C8—C6 | 107.32 (19) | O2—C17—C14 | 128.7 (3) |
C14—C8—C6 | 114.99 (19) | O3—C17—C14 | 113.3 (2) |
C8—C9—C11 | 109.5 (2) | F—C21—O3 | 107.6 (2) |
C8—C9—C10 | 101.96 (19) | F—C21—C6 | 111.0 (2) |
C11—C9—C10 | 123.4 (2) | O3—C21—C6 | 112.1 (2) |
C1—C10—C20 | 110.3 (2) | ||
C10—C1—C2—C3 | −56.4 (3) | C4—C5—C10—C9 | −176.55 (19) |
C1—C2—C3—C4 | 55.4 (3) | C6—C5—C10—C9 | 47.7 (2) |
C2—C3—C4—C18 | −167.6 (3) | C8—C9—C11—C12 | 42.3 (3) |
C2—C3—C4—C19 | 75.3 (3) | C10—C9—C11—C12 | 162.1 (2) |
C2—C3—C4—C5 | −50.3 (3) | C16—O1—C12—C13 | 0.1 (3) |
C18—C4—C5—C6 | −64.3 (3) | C16—O1—C12—C11 | 179.9 (3) |
C19—C4—C5—C6 | 56.1 (3) | C9—C11—C12—C13 | −10.6 (4) |
C3—C4—C5—C6 | 179.3 (2) | C9—C11—C12—O1 | 169.7 (2) |
C18—C4—C5—C10 | 168.3 (2) | O1—C12—C13—C15 | −0.4 (3) |
C19—C4—C5—C10 | −71.3 (3) | C11—C12—C13—C15 | 179.9 (3) |
C3—C4—C5—C10 | 51.9 (3) | O1—C12—C13—C14 | −178.3 (2) |
C4—C5—C6—C21 | 75.3 (3) | C11—C12—C13—C14 | 2.0 (4) |
C10—C5—C6—C21 | −151.3 (2) | C12—C13—C14—C17 | −145.5 (3) |
C4—C5—C6—C8 | −162.5 (2) | C15—C13—C14—C17 | 37.2 (4) |
C10—C5—C6—C8 | −29.1 (2) | C12—C13—C14—C8 | −24.8 (3) |
C21—C6—C8—C9 | 127.5 (2) | C15—C13—C14—C8 | 157.9 (3) |
C5—C6—C8—C9 | −0.9 (2) | C9—C8—C14—C17 | −173.8 (2) |
C21—C6—C8—C14 | 4.5 (3) | C6—C8—C14—C17 | −52.3 (3) |
C5—C6—C8—C14 | −123.85 (19) | C9—C8—C14—C13 | 58.2 (2) |
C14—C8—C9—C11 | −71.1 (3) | C6—C8—C14—C13 | 179.6 (2) |
C6—C8—C9—C11 | 163.0 (2) | C12—C13—C15—C16 | 0.5 (3) |
C14—C8—C9—C10 | 156.75 (19) | C14—C13—C15—C16 | 178.0 (3) |
C6—C8—C9—C10 | 30.9 (2) | C13—C15—C16—O1 | −0.4 (3) |
C2—C1—C10—C20 | −71.4 (3) | C12—O1—C16—C15 | 0.2 (3) |
C2—C1—C10—C9 | 164.4 (2) | C21—O3—C17—O2 | 174.9 (2) |
C2—C1—C10—C5 | 55.3 (3) | C21—O3—C17—C14 | −4.1 (4) |
C8—C9—C10—C1 | −162.5 (2) | C13—C14—C17—O2 | −5.8 (4) |
C11—C9—C10—C1 | 74.3 (3) | C8—C14—C17—O2 | −125.9 (3) |
C8—C9—C10—C20 | 72.9 (2) | C13—C14—C17—O3 | 173.1 (2) |
C11—C9—C10—C20 | −50.4 (3) | C8—C14—C17—O3 | 53.0 (3) |
C8—C9—C10—C5 | −47.5 (2) | C17—O3—C21—F | 74.3 (3) |
C11—C9—C10—C5 | −170.8 (2) | C17—O3—C21—C6 | −48.0 (3) |
C4—C5—C10—C1 | −56.6 (3) | C8—C6—C21—F | −75.9 (3) |
C6—C5—C10—C1 | 167.69 (19) | C5—C6—C21—F | 43.1 (3) |
C4—C5—C10—C20 | 67.4 (3) | C8—C6—C21—O3 | 44.5 (3) |
C6—C5—C10—C20 | −68.4 (2) | C5—C6—C21—O3 | 163.5 (2) |
Experimental details
Crystal data | |
Chemical formula | C20H25FO3 |
Mr | 332.40 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 293 |
a, b, c (Å) | 9.440 (1), 9.366 (1), 9.741 (1) |
β (°) | 101.69 (1) |
V (Å3) | 843.4 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.45 × 0.40 × 0.08 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.961, 0.993 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1920, 1813, 1571 |
Rint | 0.031 |
(sin θ/λ)max (Å−1) | 0.623 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.097, 1.11 |
No. of reflections | 1813 |
No. of parameters | 218 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.14, −0.19 |
Absolute structure | Flack H D (1983), Acta Cryst. A39, 876-881 |
Absolute structure parameter | −0.6 (12) |
Computer programs: CAD-4 Software (Enraf Nonius, 1989), CAD-4 Software, SDP (Fair, 1990), SHELXS86 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996), SHELXL97.
F—C21 | 1.390 (3) | C6—C8 | 1.533 (4) |
O2—C17 | 1.192 (3) | C8—C9 | 1.528 (3) |
O3—C17 | 1.387 (4) | C8—C14 | 1.533 (3) |
O3—C21 | 1.421 (3) | C9—C11 | 1.531 (4) |
C5—C6 | 1.550 (3) | C9—C10 | 1.539 (3) |
C5—C10 | 1.560 (3) | C13—C14 | 1.509 (4) |
C6—C21 | 1.518 (3) | C14—C17 | 1.488 (4) |
C17—O3—C21 | 120.2 (2) | C11—C9—C10 | 123.4 (2) |
C4—C5—C6 | 121.2 (2) | C1—C10—C9 | 115.0 (2) |
C4—C5—C10 | 117.0 (2) | C1—C10—C5 | 108.4 (2) |
C6—C5—C10 | 103.10 (19) | C17—C14—C13 | 119.0 (2) |
C21—C6—C8 | 109.7 (2) | C17—C14—C8 | 107.1 (2) |
C21—C6—C5 | 119.4 (2) | C13—C14—C8 | 106.1 (2) |
C8—C6—C5 | 103.42 (19) | O2—C17—O3 | 117.9 (3) |
C9—C8—C14 | 110.21 (19) | O2—C17—C14 | 128.7 (3) |
C9—C8—C6 | 107.32 (19) | O3—C17—C14 | 113.3 (2) |
C14—C8—C6 | 114.99 (19) | F—C21—O3 | 107.6 (2) |
C8—C9—C11 | 109.5 (2) | F—C21—C6 | 111.0 (2) |
C8—C9—C10 | 101.96 (19) | O3—C21—C6 | 112.1 (2) |
As part of our investigation of the structural requirements for the biological activities presented by derivatives of the diterpenoid 6α,7β-dihydroxyvouacapan-17β-oic acid, (I), isolated from Pterodon polygalaeflorus Benth (Rubinger et al., 1991), we have described recently an attempt to substitute the hydroxyl groups of compounds (I) and 6α-hydroxyvouacapane-7β,17β-lactone, (II), with fluorine atoms (Demuner et al., 1998). In both cases the fluorine derivative 21α-fluoro-7-norvouacapane-17β,21α-lactone, (III), has been obtained. The introduction of fluorine atoms into new molecules is a common strategy for the development of new drugs (Wilkinson, 1992). Our purpose in this case was to produce more lipophilic analogues of compounds (I) and (II) that would still be able to make hydrogen bonds at position eight and would be less sterically hindered at that position. \sch
The structure of compound (III) was proposed based on spectroscopic data. The EIMS showed a M+ ion peak at m/z 332.1784, corresponding to the molecular formula C20H25O3F. In the infrared spectrum, no absorption around 3300 cm−1 was observed, indicating that no hydroxyl group was present in the molecule. Further evidence for the presence of fluorine in this molecule comes from the 19F-NMR spectrum that showed only one double doublet (JF,H21 = 54 Hz and JF,H6 = 33 Hz) at δ −128.1. We now present the X-ray study that confirms the proposed structure of this rearranged diterpenoid. This was important as the product obtained has resulted from an unexpected rearrangment. An ORTEPIII (Burnett & Johnson, 1996) drawing of the title compound is shown in Figure 1.
A conformation analysis (Cremer & Pople, 1975; Iulek & Zukerman-Schpector, 1997), of (III) shows that the A [q2 = 0.040 (3) Å, q3 = 0.556 (3) Å, Q = 0.557 (3) Å, θ = 4.1 (3)°, ϕ = 340 (4)°] and C [q2 = 0.418 (3) Å, q3 = 0.365 (3) Å, Q = 0.555 (3) Å, θ = 48.8 (3)°, ϕ = 15.7 (4)°] rings, respectively, adopt chair and distorted half chair conformations, like its precursors (I) (Ruggiero et al., 1997) and (II) (Abrahão-Junior et al., 1997). The B [q2 = 0.501 (3) Å, ϕ = 323.6 (3)°] and D [q2 = 0.685 (3) Å, q3 = −0.049 (3) Å, Q = 0.687 (3) Å, θ = 94.1 (2)°, ϕ = 301.2 (2)°] rings have envelope and boat conformations, respectively.
The junctions of the rings AB, BC and CD are trans and the junction BD is cis. Some bond distances and angles of the norvouacapan fused rings are shown in Table 1. In the crystal packing there is a short contact: F···C1i = 3.525 (3) Å, F···H11i = 2.808, F···H11i—C1i = 131° (i = 2 − x, 1/2 + y, 1 − z).