Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102009393/fr1378sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270102009393/fr1378Isup2.hkl |
CCDC reference: 192980
11β,21-Dihydroxy-4-pregnene-3,20-dione of known absolute stereochemistry was purchased from Steraloids Inc., Newport, Rhode Island, USA, and oxidatively cleaved by NaIO4 in aqueous dioxane. Jones oxidation of the crude product provided compound (I), of known rotation (Mason et al., 1937). Crystals suitable for X-ray analysiswere produced from acetone (m.p. 543 K).
All H atoms were found in electron-density difference maps but were placed in calculated positions and allowed to refine as riding models, except for the hydroxyl H atom, whose positional and displacement parameters were all allowed to refine. The vinyl H atom was fixed at a distance of 0.93 Å, the methine H atoms at 0.98 Å, the methylene H atoms at 0.97 Å, and the methyl H atoms at 0.96 Å from their respective C atoms. The Uiso value for each methylene H atom was fixed at 120% of the isotropic displacement parameter of its C atom and for each methyl H atom, at 150% of that of its C atom. The absolute configuration of (I) was not determined (see Experimental); Friedel pairs were averaged.
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C20H26O4 | Dx = 1.225 Mg m−3 |
Mr = 330.41 | Melting point: 543 K |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.699 (2) Å | Cell parameters from 36 reflections |
b = 11.409 (3) Å | θ = 3.5–11.3° |
c = 11.764 (3) Å | µ = 0.08 mm−1 |
β = 94.98 (2)° | T = 296 K |
V = 895.7 (4) Å3 | Parallelepiped, colourless |
Z = 2 | 0.38 × 0.27 × 0.14 mm |
F(000) = 356 |
Siemens P4 diffractometer | 1245 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.057 |
Graphite monochromator | θmax = 25.0°, θmin = 2.5° |
2θ/θ scans | h = −7→7 |
Absorption correction: numerical (Sheldrick, 1997) | k = −13→13 |
Tmin = 0.97, Tmax = 0.99 | l = −13→13 |
3582 measured reflections | 3 standard reflections every 97 reflections |
1657 independent reflections | intensity decay: variation <3.5% |
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)] = 0.041 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.085 | w = 1/[σ2(Fo2) + (0.0103P)2 + 0.057P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
1658 reflections | Δρmax = 0.11 e Å−3 |
222 parameters | Δρmin = −0.11 e Å−3 |
1 restraint | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0187 (17) |
C20H26O4 | V = 895.7 (4) Å3 |
Mr = 330.41 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 6.699 (2) Å | µ = 0.08 mm−1 |
b = 11.409 (3) Å | T = 296 K |
c = 11.764 (3) Å | 0.38 × 0.27 × 0.14 mm |
β = 94.98 (2)° |
Siemens P4 diffractometer | 1245 reflections with I > 2σ(I) |
Absorption correction: numerical (Sheldrick, 1997) | Rint = 0.057 |
Tmin = 0.97, Tmax = 0.99 | 3 standard reflections every 97 reflections |
3582 measured reflections | intensity decay: variation <3.5% |
1657 independent reflections |
R[F2 > 2σ(F2)] = 0.041 | 1 restraint |
wR(F2) = 0.085 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.11 e Å−3 |
1658 reflections | Δρmin = −0.11 e Å−3 |
222 parameters |
Experimental. Crystal mounted on glass fiber using epoxy resin |
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 | ||
O1 | 0.5654 (5) | 0.4336 (3) | 1.0660 (3) | 0.1145 (12) | |
O2 | −0.0837 (4) | 0.4693 (2) | 0.6111 (2) | 0.0634 (7) | |
O3 | −0.0381 (5) | 0.6385 (3) | 0.1058 (2) | 0.0923 (9) | |
O4 | −0.0811 (6) | 0.4650 (3) | 0.1819 (3) | 0.0926 (9) | |
C1 | 0.2202 (6) | 0.4289 (3) | 0.8147 (3) | 0.0610 (10) | |
C2 | 0.2677 (7) | 0.4239 (4) | 0.9436 (3) | 0.0769 (12) | |
C3 | 0.4718 (7) | 0.4692 (4) | 0.9789 (3) | 0.0731 (11) | |
C4 | 0.5462 (6) | 0.5626 (3) | 0.9109 (3) | 0.0637 (9) | |
C5 | 0.4484 (5) | 0.6036 (3) | 0.8153 (3) | 0.0508 (9) | |
C6 | 0.5225 (5) | 0.7108 (3) | 0.7567 (3) | 0.0592 (9) | |
C7 | 0.5276 (5) | 0.6919 (3) | 0.6284 (3) | 0.0581 (10) | |
C8 | 0.3268 (4) | 0.6520 (3) | 0.5721 (3) | 0.0438 (7) | |
C9 | 0.2582 (4) | 0.5393 (2) | 0.6326 (3) | 0.0432 (7) | |
C10 | 0.2503 (5) | 0.5523 (3) | 0.7644 (3) | 0.0460 (8) | |
C11 | 0.0711 (5) | 0.4878 (3) | 0.5674 (3) | 0.0475 (8) | |
C12 | 0.0858 (5) | 0.4657 (3) | 0.4422 (3) | 0.0541 (9) | |
C13 | 0.1393 (5) | 0.5809 (3) | 0.3855 (3) | 0.0460 (8) | |
C14 | 0.3369 (4) | 0.6266 (3) | 0.4454 (3) | 0.0478 (8) | |
C15 | 0.3973 (5) | 0.7249 (3) | 0.3673 (3) | 0.0591 (10) | |
C16 | 0.3272 (6) | 0.6814 (4) | 0.2462 (3) | 0.0748 (11) | |
C17 | 0.1947 (5) | 0.5736 (3) | 0.2598 (3) | 0.0611 (10) | |
C18 | −0.0349 (5) | 0.6666 (3) | 0.3925 (3) | 0.0515 (8) | |
C19 | 0.0792 (5) | 0.6361 (4) | 0.7939 (3) | 0.0639 (10) | |
C20 | 0.0140 (6) | 0.5647 (4) | 0.1736 (3) | 0.0666 (10) | |
H4 | −0.212 (8) | 0.458 (5) | 0.133 (4) | 0.126 (18)* | |
H1A | 0.0823 | 0.4048 | 0.7962 | 0.073* | |
H1B | 0.3056 | 0.3737 | 0.7791 | 0.073* | |
H2A | 0.1696 | 0.4700 | 0.9801 | 0.092* | |
H2B | 0.2576 | 0.3434 | 0.9692 | 0.092* | |
H4A | 0.6692 | 0.5960 | 0.9351 | 0.076* | |
H6A | 0.6562 | 0.7300 | 0.7898 | 0.071* | |
H6B | 0.4356 | 0.7765 | 0.7697 | 0.071* | |
H7A | 0.5657 | 0.7646 | 0.5934 | 0.070* | |
H7B | 0.6284 | 0.6336 | 0.6154 | 0.070* | |
H8 | 0.2279 | 0.7140 | 0.5804 | 0.053* | |
H9 | 0.3642 | 0.4817 | 0.6236 | 0.052* | |
H12A | −0.0411 | 0.4365 | 0.4074 | 0.065* | |
H12B | 0.1880 | 0.4074 | 0.4321 | 0.065* | |
H14 | 0.4357 | 0.5639 | 0.4404 | 0.057* | |
H15A | 0.5412 | 0.7370 | 0.3754 | 0.071* | |
H15B | 0.3313 | 0.7978 | 0.3841 | 0.071* | |
H16A | 0.2518 | 0.7423 | 0.2039 | 0.090* | |
H16B | 0.4417 | 0.6608 | 0.2052 | 0.090* | |
H17 | 0.2772 | 0.5035 | 0.2524 | 0.073* | |
H18A | −0.0695 | 0.6711 | 0.4699 | 0.077* | |
H18B | −0.1486 | 0.6396 | 0.3443 | 0.077* | |
H18C | 0.0041 | 0.7428 | 0.3677 | 0.077* | |
H19A | 0.0786 | 0.6420 | 0.8753 | 0.096* | |
H19B | −0.0472 | 0.6056 | 0.7622 | 0.096* | |
H19C | 0.1005 | 0.7122 | 0.7625 | 0.096* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.133 (3) | 0.132 (3) | 0.0690 (19) | −0.045 (2) | −0.0405 (19) | 0.036 (2) |
O2 | 0.0581 (15) | 0.0667 (16) | 0.0651 (15) | −0.0216 (14) | 0.0031 (12) | 0.0022 (13) |
O3 | 0.115 (2) | 0.089 (2) | 0.0677 (17) | −0.002 (2) | −0.0210 (16) | 0.0205 (18) |
O4 | 0.121 (3) | 0.081 (2) | 0.0706 (19) | −0.017 (2) | −0.0248 (18) | 0.0159 (16) |
C1 | 0.074 (2) | 0.062 (2) | 0.047 (2) | −0.015 (2) | 0.0030 (18) | 0.0010 (18) |
C2 | 0.100 (3) | 0.080 (3) | 0.051 (2) | −0.026 (2) | 0.009 (2) | 0.002 (2) |
C3 | 0.090 (3) | 0.088 (3) | 0.040 (2) | −0.018 (3) | −0.003 (2) | 0.000 (2) |
C4 | 0.067 (2) | 0.073 (2) | 0.049 (2) | −0.017 (2) | −0.0035 (18) | −0.004 (2) |
C5 | 0.0543 (19) | 0.054 (2) | 0.045 (2) | −0.0014 (17) | 0.0099 (16) | −0.0106 (15) |
C6 | 0.054 (2) | 0.058 (2) | 0.064 (2) | −0.0145 (19) | −0.0030 (18) | −0.0010 (18) |
C7 | 0.053 (2) | 0.061 (2) | 0.059 (2) | −0.0069 (18) | 0.0024 (18) | 0.0082 (17) |
C8 | 0.0394 (16) | 0.0426 (18) | 0.0497 (17) | 0.0028 (15) | 0.0051 (14) | 0.0022 (14) |
C9 | 0.0451 (17) | 0.0393 (16) | 0.0451 (17) | 0.0054 (16) | 0.0033 (14) | −0.0025 (14) |
C10 | 0.0508 (19) | 0.0456 (18) | 0.0419 (17) | −0.0086 (17) | 0.0057 (15) | −0.0036 (15) |
C11 | 0.054 (2) | 0.0344 (17) | 0.053 (2) | −0.0070 (17) | −0.0001 (16) | 0.0047 (15) |
C12 | 0.064 (2) | 0.0429 (18) | 0.054 (2) | −0.0012 (18) | −0.0051 (17) | −0.0015 (17) |
C13 | 0.0488 (18) | 0.0445 (19) | 0.0445 (18) | 0.0088 (16) | 0.0037 (15) | 0.0070 (15) |
C14 | 0.0391 (17) | 0.0505 (18) | 0.054 (2) | 0.0119 (15) | 0.0060 (15) | 0.0064 (17) |
C15 | 0.046 (2) | 0.071 (2) | 0.062 (2) | 0.0029 (19) | 0.0102 (18) | 0.0155 (18) |
C16 | 0.075 (3) | 0.088 (3) | 0.063 (2) | 0.007 (2) | 0.016 (2) | 0.019 (2) |
C17 | 0.068 (2) | 0.067 (2) | 0.049 (2) | 0.018 (2) | 0.0062 (17) | 0.0003 (18) |
C18 | 0.0437 (18) | 0.0492 (18) | 0.061 (2) | 0.0043 (16) | 0.0016 (16) | 0.0034 (16) |
C19 | 0.053 (2) | 0.074 (2) | 0.066 (2) | 0.002 (2) | 0.0134 (18) | −0.012 (2) |
C20 | 0.090 (3) | 0.067 (2) | 0.043 (2) | 0.012 (3) | 0.005 (2) | 0.003 (2) |
O1—C3 | 1.223 (5) | O4—H4 | 1.01 (6) |
O2—C11 | 1.215 (4) | C1—H1A | 0.9700 |
O3—C20 | 1.192 (4) | C1—H1B | 0.9700 |
O4—C20 | 1.311 (5) | C2—H2A | 0.9700 |
C1—C2 | 1.524 (5) | C2—H2B | 0.9700 |
C1—C10 | 1.547 (5) | C4—H4A | 0.9300 |
C2—C3 | 1.487 (6) | C6—H6A | 0.9700 |
C3—C4 | 1.447 (5) | C6—H6B | 0.9700 |
C4—C5 | 1.336 (5) | C7—H7A | 0.9700 |
C5—C6 | 1.509 (5) | C7—H7B | 0.9700 |
C5—C10 | 1.525 (4) | C8—H8 | 0.9800 |
C6—C7 | 1.528 (5) | C9—H9 | 0.9800 |
C7—C8 | 1.517 (4) | C12—H12A | 0.9700 |
C8—C14 | 1.526 (4) | C12—H12B | 0.9700 |
C8—C9 | 1.557 (4) | C14—H14 | 0.9800 |
C9—C11 | 1.528 (4) | C15—H15A | 0.9700 |
C9—C10 | 1.563 (4) | C15—H15B | 0.9700 |
C10—C19 | 1.555 (5) | C16—H16A | 0.9700 |
C11—C12 | 1.507 (4) | C16—H16B | 0.9700 |
C12—C13 | 1.530 (4) | C17—H17 | 0.9800 |
C13—C18 | 1.530 (4) | C18—H18A | 0.9600 |
C13—C14 | 1.536 (5) | C18—H18B | 0.9600 |
C13—C17 | 1.558 (4) | C18—H18C | 0.9600 |
C14—C15 | 1.527 (4) | C19—H19A | 0.9600 |
C15—C16 | 1.542 (5) | C19—H19B | 0.9600 |
C16—C17 | 1.533 (5) | C19—H19C | 0.9600 |
C17—C20 | 1.514 (5) | ||
C2—C1—C10 | 113.1 (3) | C1—C2—H2B | 109.2 |
C3—C2—C1 | 111.9 (3) | H2A—C2—H2B | 107.9 |
O1—C3—C4 | 122.1 (4) | C5—C4—H4A | 118.1 |
O1—C3—C2 | 120.7 (4) | C3—C4—H4A | 118.1 |
C4—C3—C2 | 117.0 (4) | C5—C6—H6A | 109.2 |
C5—C4—C3 | 123.8 (3) | C7—C6—H6A | 109.2 |
C4—C5—C6 | 120.8 (3) | C5—C6—H6B | 109.2 |
C4—C5—C10 | 122.9 (3) | C7—C6—H6B | 109.2 |
C6—C5—C10 | 116.2 (3) | H6A—C6—H6B | 107.9 |
C5—C6—C7 | 112.0 (3) | C8—C7—H7A | 109.2 |
C8—C7—C6 | 112.3 (3) | C6—C7—H7A | 109.2 |
C7—C8—C14 | 111.8 (2) | C8—C7—H7B | 109.2 |
C7—C8—C9 | 109.6 (3) | C6—C7—H7B | 109.2 |
C14—C8—C9 | 109.2 (3) | H7A—C7—H7B | 107.9 |
C11—C9—C8 | 110.5 (3) | C7—C8—H8 | 108.7 |
C11—C9—C10 | 115.9 (3) | C14—C8—H8 | 108.7 |
C8—C9—C10 | 114.3 (2) | C9—C8—H8 | 108.7 |
C5—C10—C1 | 109.7 (3) | C11—C9—H9 | 105.0 |
C5—C10—C19 | 108.0 (3) | C8—C9—H9 | 105.0 |
C1—C10—C19 | 110.5 (3) | C10—C9—H9 | 105.0 |
C5—C10—C9 | 108.9 (2) | C11—C12—H12A | 110.0 |
C1—C10—C9 | 108.1 (3) | C13—C12—H12A | 110.0 |
C19—C10—C9 | 111.7 (3) | C11—C12—H12B | 110.0 |
O2—C11—C12 | 121.0 (3) | C13—C12—H12B | 110.0 |
O2—C11—C9 | 123.2 (3) | H12A—C12—H12B | 108.3 |
C12—C11—C9 | 115.7 (3) | C8—C14—H14 | 106.5 |
C11—C12—C13 | 108.7 (3) | C15—C14—H14 | 106.5 |
C12—C13—C18 | 108.4 (3) | C13—C14—H14 | 106.5 |
C12—C13—C14 | 108.5 (3) | C14—C15—H15A | 110.9 |
C18—C13—C14 | 112.9 (3) | C16—C15—H15A | 110.9 |
C12—C13—C17 | 116.9 (3) | C14—C15—H15B | 110.9 |
C18—C13—C17 | 109.3 (3) | C16—C15—H15B | 110.9 |
C14—C13—C17 | 100.8 (2) | H15A—C15—H15B | 108.9 |
C8—C14—C15 | 119.0 (3) | C17—C16—H16A | 110.3 |
C8—C14—C13 | 113.8 (2) | C15—C16—H16A | 110.3 |
C15—C14—C13 | 103.6 (3) | C17—C16—H16B | 110.3 |
C14—C15—C16 | 104.1 (3) | C15—C16—H16B | 110.3 |
C17—C16—C15 | 107.1 (3) | H16A—C16—H16B | 108.5 |
C20—C17—C16 | 114.9 (3) | C20—C17—H17 | 108.0 |
C20—C17—C13 | 113.4 (3) | C16—C17—H17 | 108.0 |
C16—C17—C13 | 104.1 (3) | C13—C17—H17 | 108.0 |
O3—C20—O4 | 123.2 (4) | C13—C18—H18A | 109.5 |
O3—C20—C17 | 124.8 (4) | C13—C18—H18B | 109.5 |
O4—C20—C17 | 112.0 (3) | H18A—C18—H18B | 109.5 |
C20—O4—H4 | 115 (3) | C13—C18—H18C | 109.5 |
C2—C1—H1A | 109.0 | H18A—C18—H18C | 109.5 |
C10—C1—H1A | 109.0 | H18B—C18—H18C | 109.5 |
C2—C1—H1B | 109.0 | C10—C19—H19A | 109.5 |
C10—C1—H1B | 109.0 | C10—C19—H19B | 109.5 |
H1A—C1—H1B | 107.8 | H19A—C19—H19B | 109.5 |
C3—C2—H2A | 109.2 | C10—C19—H19C | 109.5 |
C1—C2—H2A | 109.2 | H19A—C19—H19C | 109.5 |
C3—C2—H2B | 109.2 | H19B—C19—H19C | 109.5 |
C10—C1—C2—C3 | −53.9 (5) | C8—C9—C11—C12 | 53.0 (3) |
C1—C2—C3—O1 | −151.9 (4) | C10—C9—C11—C12 | −174.9 (3) |
C1—C2—C3—C4 | 32.8 (5) | O2—C11—C12—C13 | 120.3 (3) |
O1—C3—C4—C5 | 179.9 (4) | C9—C11—C12—C13 | −57.1 (4) |
C2—C3—C4—C5 | −4.8 (6) | C11—C12—C13—C18 | −65.3 (4) |
C3—C4—C5—C6 | 172.4 (3) | C11—C12—C13—C14 | 57.7 (3) |
C3—C4—C5—C10 | −2.8 (6) | C11—C12—C13—C17 | 170.7 (3) |
C4—C5—C6—C7 | 132.6 (4) | C7—C8—C14—C15 | −59.7 (4) |
C10—C5—C6—C7 | −51.8 (4) | C9—C8—C14—C15 | 178.9 (3) |
C5—C6—C7—C8 | 54.3 (4) | C7—C8—C14—C13 | 177.6 (3) |
C6—C7—C8—C14 | −176.7 (3) | C9—C8—C14—C13 | 56.2 (3) |
C6—C7—C8—C9 | −55.5 (4) | C12—C13—C14—C8 | −60.8 (3) |
C7—C8—C9—C11 | −172.2 (3) | C18—C13—C14—C8 | 59.4 (3) |
C14—C8—C9—C11 | −49.5 (3) | C17—C13—C14—C8 | 175.8 (3) |
C7—C8—C9—C10 | 54.9 (3) | C12—C13—C14—C15 | 168.4 (3) |
C14—C8—C9—C10 | 177.6 (3) | C18—C13—C14—C15 | −71.4 (3) |
C4—C5—C10—C1 | −17.8 (4) | C17—C13—C14—C15 | 45.1 (3) |
C6—C5—C10—C1 | 166.8 (3) | C8—C14—C15—C16 | −162.6 (3) |
C4—C5—C10—C19 | 102.7 (4) | C13—C14—C15—C16 | −35.0 (3) |
C6—C5—C10—C19 | −72.7 (3) | C14—C15—C16—C17 | 10.9 (4) |
C4—C5—C10—C9 | −135.8 (3) | C15—C16—C17—C20 | 141.5 (3) |
C6—C5—C10—C9 | 48.8 (4) | C15—C16—C17—C13 | 16.8 (4) |
C2—C1—C10—C5 | 45.4 (4) | C12—C13—C17—C20 | 79.4 (4) |
C2—C1—C10—C19 | −73.6 (4) | C18—C13—C17—C20 | −44.2 (4) |
C2—C1—C10—C9 | 163.9 (3) | C14—C13—C17—C20 | −163.3 (3) |
C11—C9—C10—C5 | 179.5 (3) | C12—C13—C17—C16 | −155.0 (3) |
C8—C9—C10—C5 | −50.2 (3) | C18—C13—C17—C16 | 81.4 (3) |
C11—C9—C10—C1 | 60.5 (4) | C14—C13—C17—C16 | −37.7 (3) |
C8—C9—C10—C1 | −169.3 (3) | C16—C17—C20—O3 | −6.9 (5) |
C11—C9—C10—C19 | −61.3 (3) | C13—C17—C20—O3 | 112.7 (4) |
C8—C9—C10—C19 | 69.0 (3) | C16—C17—C20—O4 | 173.3 (3) |
C8—C9—C11—O2 | −124.3 (3) | C13—C17—C20—O4 | −67.1 (4) |
C10—C9—C11—O2 | 7.8 (4) |
Experimental details
Crystal data | |
Chemical formula | C20H26O4 |
Mr | 330.41 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 296 |
a, b, c (Å) | 6.699 (2), 11.409 (3), 11.764 (3) |
β (°) | 94.98 (2) |
V (Å3) | 895.7 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.38 × 0.27 × 0.14 |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | Numerical (Sheldrick, 1997) |
Tmin, Tmax | 0.97, 0.99 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3582, 1657, 1245 |
Rint | 0.057 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.085, 1.07 |
No. of reflections | 1658 |
No. of parameters | 222 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.11, −0.11 |
Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXTL (Sheldrick, 1997), SHELXTL.
O3—C20 | 1.192 (4) | O4—C20 | 1.311 (5) |
O3—C20—C17 | 124.8 (4) | O4—C20—C17 | 112.0 (3) |
The single hydrogen-bonding donor and single acceptor of a carboxylic acid generate a high predominance of dimers in the absence of other functional groups. Our interest in the crystal structures of keto acids concerns the molecular characteristics that control their five known hydrogen-bonding patterns. While acid dimers also predominate generally in keto acids, in non-racemates with significant conformational restrictions, the prevalence of acid-to-ketone catemers rises dramatically (Brunskill et al., 1999). In studying this, we have sought subject materials with terpenoid origins, and now report the crystal structure and hydrogen-bonding behavior of (+)-3,11-dioxoandrost-4-ene-17β-carboxylic acid, (I), the eighth in our series of steroidal keto acids.
Fig. 1 shows the asymmetric unit of (I) with the steroid numbering. Among the few conformational options, both methyl groups adopt the expected staggered arrangements and the carboxyl carbonyl group is turned toward C16 so that C16 lies near the carboxyl plane [torsion angle C16—C17—C20—O3 = -6.8 (5)°]. In both of the 17β-carboxy keto steroids we have previously examined, the carboxyl group is similarly oriented (Brunskill et al., 1997; Thompson et al., 1999).
Complete or partial averaging of carboxyl C—O bond lengths and C—C—O angles by disorder is frequent in hydrogen-bonding dimers (Leiserowitz, 1976). However, catemers, hydrates and other hydrogen-bonding structures whose geometry precludes the usual carboxyl-disordering processes are highly ordered, as is found here. Our own survey of 56 keto acid structures which are not acid dimers gives average values of 1.20 (1)/1.32 (2) Å and 124.5 (14)/112.7 (17)° for these lengths and angles, in accord with typical values of 1.21/1.31 Å and 123/112° cited for highly ordered dimeric carboxyls (Borthwick, 1980). In (I), these lengths and angles are 1.192 (4)/1.311 (5) Å and 124.8 (4)/112.0 (3)°. No significant disorder was detected in either methyl group.
Fig. 2 shows the packing in the cell and illustrates the two parallel catemers created by the acid-to-ketone hydrogen bonding among translationally related molecules. This hydrogen bonding involves only the remote A-ring ketone. The conjugated ketone would be both the more basic and more sterically accessible of the two. However, the choice here may be dictated more by the forces directing packing of the nonpolar portions of these generally planar molecules than by any such competition. The two chains are screw-related in b, and lie with their long axes parallel, but with opposite end-to-end orientation. This arrangement is identical to that seen in 3-oxoandrosta-1,4-diene-17β-carboxylic acid (Thompson et al., 1999), but differs markedly from that in 3-oxoandrost-4-ene-17β-carboxylic acid, whose chains diverge (Brunskill et al., 1997).
We categorize subtypes of catemers by describing the relationship of adjacent molecules in the chains as homochiral (screw and translation) and heterochiral (glide). For hydrogen-bonding catemers overall, the observed prevalence within the former grouping, appropriate to (I), is screw > translation. Among the seven steroid keto acids whose X-ray structures we have previously reported, four cases displayed catemeric hydrogen bonding. Of these four, three were translational, including both 17β-carboxy keto steroids (Brunskill et al., 1997; Thompson et al., 1999), and one involved a screw relationship. Translational catemers are not constrained to follow any crystallographic axis. Although molecules of (I) are aligned generally lengthwise along the c axis, this does not correspond to the hydrogen-bonding axis, but follows the [101] direction.
For each hydrogen bond [O···O = 2.653 (5) Å and O—H···O angle = 172 (5)°], the dihedral angle between the carboxyl (C17/C20/O2/O3) and ketone planes (C2'/C3'/C4'/O1') is 36.9 (2)°, identical with the intramolecular dihedral angle, since the chains are translational. In addition, we characterize the geometry of hydrogen bonding to carbonyls using a combination of the H···O═ C angle and the H···O═C—C torsion angle. These describe the approach of the H atom to the O in terms of its deviation from, respectively, C═O axiality (ideal = 120°) and planarity with the carbonyl (ideal = 0°). In (I), these angles are 136 (2) and -6(3)°, respectively.
A total of four intermolecular C—H···O═C close contacts to neighboring molecules was found for both ketones (see Table 2), all lying within the 2.7 Å range we normally employ for non-bonded C—H···O packing interactions (Steiner, 1997). Using compiled data for a large number of such contacts, Steiner & Desiraju (1998) find significant statistical directionality, even as far out as 3.0 Å, and conclude that these are legitimately viewed as `weak hydrogen bonds', with a greater contribution to packing forces than simple van der Waals attractions.
The KBr IR spectrum of (I) displays C═O absorptions at 1726 (COOH) and 645 cm-1 (enone), consistent with known shifts produced when hydrogen-bonding is, respectively, removed from carboxyl C═O and added to a ketone, plus a peak at 1704 cm-1 for the 11-oxo group. In CHCl3 solution, where dimers predominate, the acid and 11-oxo absorptions merge into a single broad peak at 1705 cm-1, with a carboxyl-dilution shoulder at ca 1745 cm-1. The enone peak appears, normally, at 1664 cm-1, revealing a C═C peak at 1616 cm-1, seen in the KBr spectrum only as a slight shoulder.