Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803004276/om6133sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803004276/om6133Isup2.hkl |
CCDC reference: 209913
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (C-C) = 0.003 Å
- R factor = 0.041
- wR factor = 0.129
- Data-to-parameter ratio = 15.2
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Compound (I) was prepared by adding a solution of p-methoxyphenylmagnesium bromide in tetrahydrofuran (11 ml, 0.5 M, 5.5 mmol) dropwise over a period of 30 min to a stirred solution of keto acid (V) (0.207 g, 0.98 mmol; Xie et al., 2002b) in tetrahydrofuran (20 ml) which was flushed with argon and maintained in an ice bath. The mixture was stirred in the ice bath for an additional 30 min, then at room temperature for 2 h, and finally under reflux for 30 min. It was acidified with 3 N HCl and extracted with ether. The extracts were dried and concentrated in vacuo to a brown pasty solid to which benzene (5 ml) and p-TsOH·H2O (0.07 g) were added, and the solution was refluxed for 2 h. The benzene was then removed by evaporation, water was added and the mixture was extracted with ether. Evaporation of the extracts and purification of the residue chromatographically provided a major fraction which crystallized on removal of the solvent; pure (I), m.p. 388–388.8 K (recrystallized, CH2Cl2-hexane). This fraction was the most polar, indicating the absence of a carboxylic acid, e.g. (IV). IR (neat): 1753 cm−1; NMR (CDCl3), 1H (300 MHz): δ 0.82 (t, J = 7.2 Hz, 3H), 1.10 (m, J = 7.2 Hz, 2H), 1.12 (s, 3H), 1.15 (d, J = 6.6 Hz, 3H), 1.23 (s, 3H), 1.35 (m, J = 6.3 Hz, 1H), 1.82 (dd, J = 13.8 Hz, 1.8 Hz, 1H), 2.08 (m, J = 7.2 Hz, 1H), 2.13 (d, J = 1.8 Hz, 1H), 2.19 (d, J = 13.8 Hz, 1H), 3.81 (s, 3H), 6.88 (d, J = 8.7 Hz, 2H), 7.29 (d, J = 9.0 Hz, 2H); 13C (75 MHz): δ 12.39, 22.85, 24.65, 27.53, 32.02, 32.12, 32.23, 38.80, 53.50, 55.25, 55.83, 88.05, 113.42, 127.13, 133.31 (2 C), 159.12 (2 C), 175.89.
The rotational orientations of the methyl H atoms were refined by the circular Fourier method available in SHELXL97 (Sheldrick, 1997). All H atoms were refined as riding, with C—H distances ranging from 0.93 to 0.98 Å.
Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: PROCESS in TEXSAN (Molecular Structure Corporation, 1997); program(s) used to solve structure: SIR92 (Burla et al., 1989); program(s) used to refine structure: LS in TEXSAN and SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: TEXSAN, SHELXL97 and PLATON (Spek, 2000).
Fig. 1. The molecular structure and atom-numbering scheme for (I), with displacement ellipsoids at the 30% probability level. |
C19H26O3 | F(000) = 1312 |
Mr = 302.40 | Dx = 1.155 Mg m−3 |
Monoclinic, C2/c | Melting point = 388–388.8 K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71069 Å |
a = 32.326 (4) Å | Cell parameters from 25 reflections |
b = 7.1937 (12) Å | θ = 16.1–19.3° |
c = 15.4134 (19) Å | µ = 0.08 mm−1 |
β = 104.022 (9)° | T = 296 K |
V = 3477.5 (9) Å3 | Irregular fragment, colorless |
Z = 8 | 0.49 × 0.33 × 0.27 mm |
Rigaku AFC-5S diffractometer | Rint = 0.012 |
Radiation source: fine-focus sealed tube | θmax = 25.1°, θmin = 2.6° |
Graphite monochromator | h = 0→38 |
ω scans | k = 0→8 |
3156 measured reflections | l = −18→17 |
3098 independent reflections | 3 standard reflections every 100 reflections |
1775 reflections with I > 2σ(I) | intensity decay: 0.3% |
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.129 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0578P)2 + 1.278P] where P = (Fo2 + 2Fc2)/3 |
3098 reflections | (Δ/σ)max = 0.001 |
204 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C19H26O3 | V = 3477.5 (9) Å3 |
Mr = 302.40 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 32.326 (4) Å | µ = 0.08 mm−1 |
b = 7.1937 (12) Å | T = 296 K |
c = 15.4134 (19) Å | 0.49 × 0.33 × 0.27 mm |
β = 104.022 (9)° |
Rigaku AFC-5S diffractometer | Rint = 0.012 |
3156 measured reflections | 3 standard reflections every 100 reflections |
3098 independent reflections | intensity decay: 0.3% |
1775 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.129 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.13 e Å−3 |
3098 reflections | Δρmin = −0.19 e Å−3 |
204 parameters |
x | y | z | Uiso*/Ueq | ||
O1 | 0.93871 (5) | 1.1412 (2) | 0.49181 (13) | 0.0736 (5) | |
O2 | 0.88085 (4) | 0.97256 (18) | 0.43861 (9) | 0.0461 (4) | |
O3 | 0.68514 (4) | 0.8026 (2) | 0.32443 (11) | 0.0666 (5) | |
C1 | 0.86610 (6) | 0.7784 (3) | 0.41856 (13) | 0.0392 (5) | |
C3 | 0.92363 (6) | 0.9899 (3) | 0.47143 (14) | 0.0492 (5) | |
C4 | 0.94654 (6) | 0.8088 (3) | 0.47569 (14) | 0.0465 (5) | |
C5 | 0.93708 (6) | 0.7320 (3) | 0.37866 (13) | 0.0461 (5) | |
C6 | 0.88812 (6) | 0.7053 (3) | 0.34840 (13) | 0.0454 (5) | |
C7 | 0.88039 (6) | 0.6711 (3) | 0.50733 (13) | 0.0431 (5) | |
C8 | 0.92946 (6) | 0.6819 (3) | 0.53923 (13) | 0.0463 (5) | |
C9 | 0.95205 (7) | 0.8732 (4) | 0.31840 (16) | 0.0709 (7) | |
C10 | 0.96094 (7) | 0.5495 (4) | 0.37558 (16) | 0.0660 (7) | |
C11 | 0.86319 (7) | 0.4719 (3) | 0.50172 (15) | 0.0550 (6) | |
C12 | 0.87329 (9) | 0.3698 (4) | 0.59109 (17) | 0.0769 (8) | |
C13 | 0.94435 (8) | 0.7514 (4) | 0.63569 (14) | 0.0714 (7) | |
C14 | 0.81795 (6) | 0.7904 (3) | 0.38787 (13) | 0.0415 (5) | |
C15 | 0.79488 (6) | 0.6831 (3) | 0.31862 (14) | 0.0529 (6) | |
C16 | 0.75064 (6) | 0.6822 (3) | 0.29586 (15) | 0.0565 (6) | |
C17 | 0.72884 (6) | 0.7921 (3) | 0.34206 (14) | 0.0479 (5) | |
C18 | 0.75103 (6) | 0.9034 (3) | 0.41006 (15) | 0.0541 (6) | |
C19 | 0.79494 (6) | 0.9019 (3) | 0.43308 (14) | 0.0496 (5) | |
C20 | 0.66146 (7) | 0.6837 (4) | 0.2573 (2) | 0.0888 (9) | |
H4 | 0.9773 | 0.8278 | 0.4986 | 0.056* | |
H6A | 0.8772 | 0.7706 | 0.2925 | 0.054* | |
H6B | 0.8817 | 0.5743 | 0.3382 | 0.054* | |
H7 | 0.8687 | 0.7369 | 0.5517 | 0.052* | |
H8 | 0.9410 | 0.5568 | 0.5361 | 0.056* | |
H9A | 0.9822 | 0.8922 | 0.3395 | 0.106* | |
H9B | 0.9375 | 0.9890 | 0.3197 | 0.106* | |
H9C | 0.9459 | 0.8269 | 0.2582 | 0.106* | |
H10A | 0.9558 | 0.5072 | 0.3148 | 0.099* | |
H10B | 0.9510 | 0.4576 | 0.4110 | 0.099* | |
H10C | 0.9909 | 0.5691 | 0.3990 | 0.099* | |
H11A | 0.8325 | 0.4753 | 0.4785 | 0.066* | |
H11B | 0.8752 | 0.4024 | 0.4597 | 0.066* | |
H12A | 0.9036 | 0.3602 | 0.6133 | 0.115* | |
H12B | 0.8611 | 0.2475 | 0.5830 | 0.115* | |
H12C | 0.8615 | 0.4374 | 0.6332 | 0.115* | |
H13A | 0.9749 | 0.7513 | 0.6532 | 0.107* | |
H13B | 0.9334 | 0.6711 | 0.6746 | 0.107* | |
H13C | 0.9340 | 0.8755 | 0.6397 | 0.107* | |
H15 | 0.8094 | 0.6092 | 0.2863 | 0.063* | |
H16 | 0.7359 | 0.6073 | 0.2494 | 0.068* | |
H18 | 0.7363 | 0.9802 | 0.4407 | 0.065* | |
H19 | 0.8095 | 0.9769 | 0.4797 | 0.060* | |
H20A | 0.6691 | 0.7073 | 0.2019 | 0.133* | |
H20B | 0.6316 | 0.7066 | 0.2500 | 0.133* | |
H20C | 0.6677 | 0.5566 | 0.2746 | 0.133* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0492 (9) | 0.0464 (10) | 0.1211 (15) | −0.0014 (8) | 0.0125 (9) | −0.0143 (10) |
O2 | 0.0371 (7) | 0.0388 (8) | 0.0598 (9) | 0.0058 (6) | 0.0066 (6) | −0.0011 (7) |
O3 | 0.0359 (8) | 0.0801 (12) | 0.0837 (12) | −0.0028 (8) | 0.0141 (8) | −0.0207 (9) |
C1 | 0.0376 (10) | 0.0366 (11) | 0.0429 (11) | 0.0050 (9) | 0.0087 (8) | −0.0013 (9) |
C3 | 0.0410 (11) | 0.0476 (13) | 0.0588 (13) | 0.0035 (10) | 0.0114 (10) | −0.0029 (11) |
C4 | 0.0348 (10) | 0.0515 (13) | 0.0504 (12) | 0.0068 (9) | 0.0050 (9) | −0.0055 (10) |
C5 | 0.0384 (10) | 0.0559 (13) | 0.0444 (11) | 0.0099 (10) | 0.0111 (9) | −0.0002 (10) |
C6 | 0.0415 (11) | 0.0533 (13) | 0.0410 (11) | 0.0074 (9) | 0.0091 (9) | −0.0015 (10) |
C7 | 0.0465 (11) | 0.0441 (12) | 0.0401 (11) | 0.0111 (9) | 0.0130 (9) | −0.0012 (9) |
C8 | 0.0447 (11) | 0.0512 (13) | 0.0408 (11) | 0.0134 (9) | 0.0060 (9) | −0.0017 (9) |
C9 | 0.0567 (14) | 0.095 (2) | 0.0650 (16) | −0.0025 (14) | 0.0215 (12) | 0.0108 (15) |
C10 | 0.0558 (13) | 0.0811 (17) | 0.0585 (15) | 0.0255 (13) | 0.0089 (11) | −0.0162 (13) |
C11 | 0.0589 (14) | 0.0470 (13) | 0.0602 (14) | 0.0067 (11) | 0.0166 (11) | 0.0046 (11) |
C12 | 0.107 (2) | 0.0589 (16) | 0.0715 (17) | 0.0128 (15) | 0.0353 (15) | 0.0160 (14) |
C13 | 0.0694 (15) | 0.094 (2) | 0.0448 (13) | 0.0064 (15) | 0.0018 (11) | −0.0072 (13) |
C14 | 0.0385 (10) | 0.0439 (12) | 0.0419 (11) | 0.0042 (9) | 0.0096 (9) | 0.0016 (9) |
C15 | 0.0428 (11) | 0.0564 (14) | 0.0597 (14) | 0.0066 (10) | 0.0128 (10) | −0.0157 (11) |
C16 | 0.0431 (12) | 0.0582 (14) | 0.0641 (14) | −0.0010 (10) | 0.0048 (11) | −0.0188 (12) |
C17 | 0.0377 (11) | 0.0512 (13) | 0.0555 (13) | 0.0018 (10) | 0.0123 (9) | 0.0003 (11) |
C18 | 0.0425 (12) | 0.0634 (14) | 0.0587 (14) | 0.0065 (11) | 0.0167 (10) | −0.0128 (12) |
C19 | 0.0442 (12) | 0.0574 (14) | 0.0464 (12) | 0.0030 (10) | 0.0092 (9) | −0.0101 (10) |
C20 | 0.0412 (13) | 0.097 (2) | 0.121 (2) | −0.0087 (14) | 0.0064 (14) | −0.0348 (19) |
C3—C4 | 1.492 (3) | C6—H6A | 0.9700 |
O2—C3 | 1.358 (2) | C6—H6B | 0.9700 |
O2—C1 | 1.484 (2) | C7—H7 | 0.9800 |
O1—C3 | 1.203 (3) | C8—H8 | 0.9800 |
O3—C17 | 1.374 (2) | C9—H9A | 0.9600 |
O3—C20 | 1.415 (3) | C9—H9B | 0.9600 |
C1—C14 | 1.516 (2) | C9—H9C | 0.9600 |
C1—C6 | 1.525 (2) | C10—H10A | 0.9600 |
C1—C7 | 1.541 (3) | C10—H10B | 0.9600 |
C4—C8 | 1.536 (3) | C10—H10C | 0.9600 |
C4—C5 | 1.554 (3) | C11—H11A | 0.9700 |
C5—C10 | 1.529 (3) | C11—H11B | 0.9700 |
C5—C9 | 1.532 (3) | C12—H12A | 0.9600 |
C5—C6 | 1.550 (3) | C12—H12B | 0.9600 |
C7—C11 | 1.532 (3) | C12—H12C | 0.9600 |
C7—C8 | 1.545 (3) | C13—H13A | 0.9600 |
C8—C13 | 1.531 (3) | C13—H13B | 0.9600 |
C11—C12 | 1.525 (3) | C13—H13C | 0.9600 |
C14—C15 | 1.380 (3) | C15—H15 | 0.9300 |
C14—C19 | 1.391 (3) | C16—H16 | 0.9300 |
C15—C16 | 1.388 (3) | C18—H18 | 0.9300 |
C16—C17 | 1.368 (3) | C19—H19 | 0.9300 |
C17—C18 | 1.375 (3) | C20—H20A | 0.9600 |
C18—C19 | 1.377 (3) | C20—H20B | 0.9600 |
C4—H4 | 0.9800 | C20—H20C | 0.9600 |
O1—C3—C4 | 127.82 (19) | C8—C7—H7 | 107.1 |
O2—C3—C4 | 112.70 (18) | C13—C8—H8 | 108.3 |
C3—O2—C1 | 114.24 (14) | C4—C8—H8 | 108.3 |
C17—O3—C20 | 117.34 (18) | C7—C8—H8 | 108.3 |
O2—C1—C14 | 105.38 (15) | C5—C9—H9A | 109.5 |
O2—C1—C6 | 106.89 (15) | C5—C9—H9B | 109.5 |
C14—C1—C6 | 114.76 (16) | H9A—C9—H9B | 109.5 |
O2—C1—C7 | 105.92 (15) | C5—C9—H9C | 109.5 |
C14—C1—C7 | 111.70 (16) | H9A—C9—H9C | 109.5 |
C6—C1—C7 | 111.48 (16) | H9B—C9—H9C | 109.5 |
O1—C3—O2 | 119.46 (19) | C5—C10—H10A | 109.5 |
C3—C4—C8 | 107.20 (16) | C5—C10—H10B | 109.5 |
C3—C4—C5 | 106.74 (17) | H10A—C10—H10B | 109.5 |
C8—C4—C5 | 112.66 (17) | C5—C10—H10C | 109.5 |
C10—C5—C9 | 108.34 (18) | H10A—C10—H10C | 109.5 |
C10—C5—C6 | 111.74 (18) | H10B—C10—H10C | 109.5 |
C9—C5—C6 | 110.44 (17) | C12—C11—H11A | 108.8 |
C10—C5—C4 | 110.60 (17) | C7—C11—H11A | 108.8 |
C9—C5—C4 | 109.30 (19) | C12—C11—H11B | 108.8 |
C6—C5—C4 | 106.40 (15) | C7—C11—H11B | 108.8 |
C1—C6—C5 | 111.22 (16) | H11A—C11—H11B | 107.7 |
C11—C7—C1 | 113.06 (16) | C11—C12—H12A | 109.5 |
C11—C7—C8 | 113.29 (16) | C11—C12—H12B | 109.5 |
C1—C7—C8 | 108.74 (16) | H12A—C12—H12B | 109.5 |
C13—C8—C4 | 110.36 (19) | C11—C12—H12C | 109.5 |
C13—C8—C7 | 112.48 (17) | H12A—C12—H12C | 109.5 |
C4—C8—C7 | 109.08 (16) | H12B—C12—H12C | 109.5 |
C12—C11—C7 | 113.8 (2) | C8—C13—H13A | 109.5 |
C15—C14—C19 | 117.12 (18) | C8—C13—H13B | 109.5 |
C15—C14—C1 | 122.07 (18) | H13A—C13—H13B | 109.5 |
C19—C14—C1 | 120.66 (18) | C8—C13—H13C | 109.5 |
C14—C15—C16 | 121.91 (19) | H13A—C13—H13C | 109.5 |
C17—C16—C15 | 119.7 (2) | H13B—C13—H13C | 109.5 |
C16—C17—O3 | 124.28 (19) | C14—C15—H15 | 119.0 |
C16—C17—C18 | 119.60 (19) | C16—C15—H15 | 119.0 |
O3—C17—C18 | 116.11 (18) | C17—C16—H16 | 120.2 |
C17—C18—C19 | 120.45 (19) | C15—C16—H16 | 120.2 |
C18—C19—C14 | 121.2 (2) | C17—C18—H18 | 119.8 |
C3—C4—H4 | 110.0 | C19—C18—H18 | 119.8 |
C8—C4—H4 | 110.0 | C18—C19—H19 | 119.4 |
C5—C4—H4 | 110.0 | C14—C19—H19 | 119.4 |
C1—C6—H6A | 109.4 | O3—C20—H20A | 109.5 |
C5—C6—H6A | 109.4 | O3—C20—H20B | 109.5 |
C1—C6—H6B | 109.4 | H20A—C20—H20B | 109.5 |
C5—C6—H6B | 109.4 | O3—C20—H20C | 109.5 |
H6A—C6—H6B | 108.0 | H20A—C20—H20C | 109.5 |
C11—C7—H7 | 107.1 | H20B—C20—H20C | 109.5 |
C1—C7—H7 | 107.1 | ||
C1—O2—C3—C4 | 2.8 (2) | C6—C1—C7—C8 | 55.9 (2) |
C6—C1—C14—C19 | −161.08 (19) | C3—C4—C8—C13 | −69.8 (2) |
C6—C1—C14—C15 | 23.4 (3) | C5—C4—C8—C13 | 173.08 (17) |
C3—O2—C1—C14 | 177.14 (16) | C3—C4—C8—C7 | 54.3 (2) |
C3—O2—C1—C6 | −60.3 (2) | C5—C4—C8—C7 | −62.9 (2) |
C3—O2—C1—C7 | 58.64 (19) | C11—C7—C8—C13 | −106.0 (2) |
C1—O2—C3—O1 | −178.3 (2) | C1—C7—C8—C13 | 127.4 (2) |
O1—C3—C4—C8 | 119.8 (3) | C11—C7—C8—C4 | 131.24 (18) |
O2—C3—C4—C8 | −61.4 (2) | C1—C7—C8—C4 | 4.6 (2) |
O1—C3—C4—C5 | −119.2 (3) | C1—C7—C11—C12 | −174.30 (18) |
O2—C3—C4—C5 | 59.6 (2) | C8—C7—C11—C12 | 61.4 (2) |
C3—C4—C5—C10 | 177.53 (17) | O2—C1—C14—C15 | 140.74 (19) |
C8—C4—C5—C10 | −65.1 (2) | C7—C1—C14—C15 | −104.7 (2) |
C3—C4—C5—C9 | 58.3 (2) | O2—C1—C14—C19 | −43.8 (2) |
C8—C4—C5—C9 | 175.72 (16) | C7—C1—C14—C19 | 70.8 (2) |
C3—C4—C5—C6 | −60.9 (2) | C19—C14—C15—C16 | −1.4 (3) |
C8—C4—C5—C6 | 56.5 (2) | C1—C14—C15—C16 | 174.2 (2) |
O2—C1—C6—C5 | 52.9 (2) | C14—C15—C16—C17 | 0.9 (4) |
C14—C1—C6—C5 | 169.39 (17) | C15—C16—C17—O3 | 179.4 (2) |
C7—C1—C6—C5 | −62.4 (2) | C15—C16—C17—C18 | 0.6 (3) |
C10—C5—C6—C1 | 126.04 (19) | C20—O3—C17—C16 | 3.7 (3) |
C9—C5—C6—C1 | −113.3 (2) | C20—O3—C17—C18 | −177.4 (2) |
C4—C5—C6—C1 | 5.2 (2) | C16—C17—C18—C19 | −1.4 (3) |
O2—C1—C7—C11 | 173.22 (15) | O3—C17—C18—C19 | 179.6 (2) |
C14—C1—C7—C11 | 59.0 (2) | C17—C18—C19—C14 | 0.8 (4) |
C6—C1—C7—C11 | −70.9 (2) | C15—C14—C19—C18 | 0.6 (3) |
O2—C1—C7—C8 | −60.04 (18) | C1—C14—C19—C18 | −175.1 (2) |
C14—C1—C7—C8 | −174.26 (16) |
Experimental details
Crystal data | |
Chemical formula | C19H26O3 |
Mr | 302.40 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 296 |
a, b, c (Å) | 32.326 (4), 7.1937 (12), 15.4134 (19) |
β (°) | 104.022 (9) |
V (Å3) | 3477.5 (9) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.49 × 0.33 × 0.27 |
Data collection | |
Diffractometer | Rigaku AFC-5S diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3156, 3098, 1775 |
Rint | 0.012 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.129, 1.02 |
No. of reflections | 3098 |
No. of parameters | 204 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.19 |
Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996), MSC/AFC Diffractometer Control Software, PROCESS in TEXSAN (Molecular Structure Corporation, 1997), SIR92 (Burla et al., 1989), LS in TEXSAN and SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), TEXSAN, SHELXL97 and PLATON (Spek, 2000).
O1—C3—C4 | 127.82 (19) | C3—O2—C1 | 114.24 (14) |
O2—C3—C4 | 112.70 (18) | ||
C1—O2—C3—C4 | 2.8 (2) | C6—C1—C14—C15 | 23.4 (3) |
C6—C1—C14—C19 | −161.08 (19) |
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We recently reported the preparation, isolation and unequivocal diastereomer identification of (1RS,2RS,5SR,6SR)-2,6-dimethyl-4-(4-methoxyphenyl)-5-ethyl-3-cyclohexene- 1-carboxylic acid, (III), and noted that a preliminary study indicated that it definitely inhibits prostate cancer-cell proliferation (Xie et al., 2002a). Further study of (III) and related compounds in prostate therapy is being continued. The preparation and potent in vivo estrogenicity of diastereomeric carboxylic acid mixtures of (III), as well as of related (IV), were reported some time ago (Nathan & Hogg, 1956; Crenshaw et al., 1972, 1973, 1974; Dvolaitzky et al., 1974; Fouquey et al., 1975, 1976, 1978). However, single diastereomers and enantiomers apparently were neither isolated nor unequivocally characterized (nor were their estrogen-receptor binding affinities studied; cf. Meyers et al., 1988); consequently, the observed biological activities could not be associated with any one absolute structure. Based on our unequivocal characterization of the single diastereomer (III) and our study showing its potential utility in prostate therapy, we decided to prepare and unequivocally characterize diastereomer (IV) and study its biological activity. In this way, we hoped to relate such activity with distereomeric structure.
Having prepared and characterized the required starting material (V) (Xie et al., 2002b), we proceeded to convert it into (IV) in a manner similar to our synthesis of (III) (Xie et al., 2002a). However, instead of obtaining the expected carboxylic acid, (IV), we obtained the corresponding kinetically favored bicyclic δ-lactone, (I), when the reaction mixture in 3 N HCl was worked up within several hours. On repeating the reaction but allowing the mixture to remain in the 3 N HCl for several days before being worked up, the thermodynamically favored isomeric bicyclic γ-lactone, (II), was obtained (Xie et al., 2003). These transformations are illustrated in the Scheme.
The structure and atom numbering of (I) are shown in Fig. 1. Lactone (I) is basically composed of an aromatic ring appended to a [2.2.2] bicyclic system. The O—C(O)—C group is asymmetric, its O—C═O angle being 119.46 (19)° and its O═C—C angle being 127.82 (19)°. The four atoms comprising the lactone moiety, C1/O2/C3/C4, are essentially coplanar, as evidenced by the torsion angle, and the least-squares plane of this moiety is nearly perpendicular to the cyclohexane ring, the angle formed being 89.29°. Selected geometric parameters are presented in Table 1.