Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801006808/cv6020sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801006808/cv6020Isup2.hkl |
CCDC reference: 165671
A solution of (1) (4.1 g, 50 mmol) and allyltrimethylsilane (2) (11.4 g, 100 mmol) in methylene chloride under argon was cooled to 195 K. TiCl4 (9.5 g, 5.5 ml, 100 mmol) was then added dropwise and the mixture was stirred at 253 K overnight. After warming to 273 K and work up, column chromatography of the crude material (6.4 g) with hexane–ethyl acetate (19:1) gave 630 mg (8%) (3) and some other products (Helbling et al., 1999). Crystallization from hexane gave pure (3). M.p.: 377 K. 1H NMR: 5.7–5.9 (m, 1H), 5.02–5.13 (m, 2H), 3.1–3.2 (broad, 1H), 2.0–2.6 (m, 8H), 1.4–1.85 (m, 7H), 0.95–1.38 (m, 4 H), -0.05 (s, 9H). 13 C NMR (CDCl3): 135.72 (d), 117.07 (t), 83.76, 60.65 (d), 50.03 (d), 46.71 (d), 40.82 (t), 40.76 (t), 39.26 (t), 37.89 (d), 33.94 (t), 30.33 (t), 29.61 (t), 26.77 (t), 26.01 (d), -2.81 (q). MS: 320 (M+, 2), 302 (38), 261 (12), 189 (80), 155 (100), 147 (32), 83 (38), 73 (56); HR—MS: calculated for C19H30OSi [M - H2O]: 302.205510; found: 302.206594. Suitable crystals of (3) were grown from ether–hexane as colourless blocks.
The H atoms were included in calulated positions and treated as riding atoms using SHELXL default parameters. The allyl side chain is disordered. The occupancies of the two positions for atoms C6, C7 and C8 were refined to be A:B = 0.564:0.436.
Data collection: EXPOSE in IPDS Software (Stoe & Cie, 2000); cell refinement: CELL in IPDS Software; data reduction: INTEGRATE in IPDS Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON99 (Spek, 1990); software used to prepare material for publication: SHELXL97.
Fig. 1. The structure of (3) showing the numbering scheme and displacement ellipsoids at the 50% probability level. | |
Fig. 2. The crystal packing of (3); hydrogen bonding is shown as dotted lines. |
C19H32O2Si | F(000) = 704 |
Mr = 320.54 | Dx = 1.106 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 14.1445 (14) Å | Cell parameters from 5000 reflections |
b = 6.2718 (4) Å | θ = 2.1–25.9° |
c = 22.340 (2) Å | µ = 0.13 mm−1 |
β = 103.694 (11)° | T = 223 K |
V = 1925.4 (3) Å3 | Block, colourless |
Z = 4 | 0.45 × 0.40 × 0.30 mm |
Stoe IPDS diffractometer | 2809 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.036 |
Graphite monochromator | θmax = 25.9°, θmin = 2.1° |
Detector resolution: 0.81Å pixels mm-1 | h = −17→17 |
ϕ oscillation scans | k = −7→6 |
13376 measured reflections | l = −27→27 |
3691 independent reflections |
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) = 0.115 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0736P)2 + 0.0262P] where P = (Fo2 + 2Fc2)/3 |
3691 reflections | (Δ/σ)max = 0.001 |
231 parameters | Δρmax = 0.31 e Å−3 |
6 restraints | Δρmin = −0.29 e Å−3 |
C19H32O2Si | V = 1925.4 (3) Å3 |
Mr = 320.54 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 14.1445 (14) Å | µ = 0.13 mm−1 |
b = 6.2718 (4) Å | T = 223 K |
c = 22.340 (2) Å | 0.45 × 0.40 × 0.30 mm |
β = 103.694 (11)° |
Stoe IPDS diffractometer | 2809 reflections with I > 2σ(I) |
13376 measured reflections | Rint = 0.036 |
3691 independent reflections |
R[F2 > 2σ(F2)] = 0.041 | 6 restraints |
wR(F2) = 0.115 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.31 e Å−3 |
3691 reflections | Δρmin = −0.29 e Å−3 |
231 parameters |
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 | Occ. (<1) | |
Si1 | 0.66534 (3) | 0.63460 (7) | 0.21123 (2) | 0.03578 (15) | |
C1' | 0.82283 (11) | 0.2185 (3) | 0.12615 (7) | 0.0361 (3) | |
H1' | 0.8027 | 0.0675 | 0.1193 | 0.043* | |
C2' | 0.88120 (11) | 0.2850 (2) | 0.07837 (7) | 0.0357 (3) | |
O2' | 0.86121 (7) | 0.50559 (17) | 0.06421 (5) | 0.0389 (3) | |
H2' | 0.9090 | 0.5616 | 0.0550 | 0.058* | |
C3' | 0.98698 (12) | 0.2578 (3) | 0.11428 (8) | 0.0497 (4) | |
H3'A | 1.0067 | 0.1077 | 0.1162 | 0.060* | |
H3'B | 1.0313 | 0.3412 | 0.0957 | 0.060* | |
C4' | 0.98515 (11) | 0.3424 (3) | 0.17772 (8) | 0.0518 (4) | |
H4'A | 0.9810 | 0.4984 | 0.1776 | 0.062* | |
H4'B | 1.0433 | 0.2980 | 0.2085 | 0.062* | |
C5' | 0.89358 (12) | 0.2420 (3) | 0.19056 (7) | 0.0443 (4) | |
H5' | 0.9091 | 0.0998 | 0.2096 | 0.053* | |
C6' | 0.83947 (12) | 0.3758 (3) | 0.22918 (7) | 0.0423 (4) | |
H6'A | 0.8849 | 0.4668 | 0.2582 | 0.051* | |
H6'B | 0.8050 | 0.2838 | 0.2525 | 0.051* | |
C7' | 0.76722 (10) | 0.5115 (2) | 0.18233 (6) | 0.0333 (3) | |
H7' | 0.8041 | 0.6279 | 0.1683 | 0.040* | |
C8' | 0.73344 (10) | 0.3562 (3) | 0.12847 (6) | 0.0369 (3) | |
H8'A | 0.7108 | 0.4345 | 0.0898 | 0.044* | |
H8'B | 0.6802 | 0.2667 | 0.1353 | 0.044* | |
C1 | 0.90798 (14) | 0.2368 (3) | −0.02923 (8) | 0.0498 (4) | |
O1 | 0.99521 (9) | 0.2637 (2) | −0.01939 (6) | 0.0562 (4) | |
C2 | 0.85458 (12) | 0.1553 (3) | 0.01809 (7) | 0.0460 (4) | |
H2 | 0.8750 | 0.0059 | 0.0280 | 0.055* | |
C3 | 0.74763 (15) | 0.1533 (5) | −0.01618 (8) | 0.0758 (7) | |
H3A | 0.7129 | 0.2796 | −0.0056 | 0.091* | 0.564 (6) |
H3B | 0.7323 | 0.3041 | −0.0118 | 0.091* | 0.436 (6) |
C4 | 0.7483 (2) | 0.1520 (6) | −0.08502 (10) | 0.0968 (10) | |
H4A | 0.7529 | 0.0060 | −0.0997 | 0.116* | |
H4B | 0.6891 | 0.2182 | −0.1098 | 0.116* | |
C5 | 0.83684 (17) | 0.2794 (5) | −0.08872 (9) | 0.0795 (7) | |
H5A | 0.8626 | 0.2325 | −0.1236 | 0.095* | |
H5B | 0.8214 | 0.4317 | −0.0933 | 0.095* | |
C6A | 0.7037 (3) | −0.0685 (8) | 0.00554 (19) | 0.0615 (13) | 0.564 (6) |
H6A | 0.7440 | −0.1895 | −0.0008 | 0.074* | 0.564 (6) |
H6B | 0.7046 | −0.0609 | 0.0495 | 0.074* | 0.564 (6) |
C7A | 0.6020 (3) | −0.0995 (7) | −0.03112 (17) | 0.0644 (14) | 0.564 (6) |
H7AA | 0.5594 | 0.0165 | −0.0328 | 0.077* | 0.564 (6) |
C8A | 0.5665 (5) | −0.2681 (15) | −0.0606 (6) | 0.095 (2) | 0.564 (6) |
H8A | 0.6061 | −0.3886 | −0.0603 | 0.114* | 0.564 (6) |
H8B | 0.5010 | −0.2710 | −0.0824 | 0.114* | 0.564 (6) |
C6B | 0.6572 (3) | 0.0576 (8) | −0.00667 (18) | 0.0495 (15) | 0.436 (6) |
H6C | 0.6003 | 0.1174 | −0.0356 | 0.059* | 0.436 (6) |
H6D | 0.6508 | 0.0825 | 0.0355 | 0.059* | 0.436 (6) |
C7B | 0.6669 (5) | −0.1723 (9) | −0.0181 (3) | 0.0666 (18) | 0.436 (6) |
H7B | 0.7245 | −0.2394 | 0.0032 | 0.080* | 0.436 (6) |
C8B | 0.6038 (8) | −0.289 (2) | −0.0545 (8) | 0.121 (5) | 0.436 (6) |
H8C | 0.5452 | −0.2285 | −0.0767 | 0.145* | 0.436 (6) |
H8D | 0.6163 | −0.4345 | −0.0589 | 0.145* | 0.436 (6) |
C10 | 0.59107 (13) | 0.4230 (3) | 0.23706 (9) | 0.0542 (5) | |
H10A | 0.5399 | 0.4888 | 0.2529 | 0.081* | |
H10B | 0.6324 | 0.3384 | 0.2692 | 0.081* | |
H10C | 0.5623 | 0.3317 | 0.2025 | 0.081* | |
C9 | 0.58525 (13) | 0.7890 (3) | 0.14757 (8) | 0.0547 (5) | |
H9A | 0.6217 | 0.9068 | 0.1360 | 0.082* | |
H9B | 0.5299 | 0.8439 | 0.1613 | 0.082* | |
H9C | 0.5626 | 0.6965 | 0.1123 | 0.082* | |
C11 | 0.71678 (14) | 0.8137 (3) | 0.27794 (9) | 0.0563 (5) | |
H11A | 0.7574 | 0.7311 | 0.3109 | 0.084* | |
H11B | 0.6641 | 0.8783 | 0.2925 | 0.084* | |
H11C | 0.7555 | 0.9244 | 0.2650 | 0.084* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Si1 | 0.0399 (2) | 0.0337 (3) | 0.0387 (2) | −0.00322 (18) | 0.01918 (17) | −0.00023 (18) |
C1' | 0.0428 (8) | 0.0294 (8) | 0.0382 (8) | −0.0011 (6) | 0.0139 (6) | −0.0002 (6) |
C2' | 0.0370 (7) | 0.0312 (8) | 0.0418 (8) | 0.0036 (6) | 0.0149 (6) | 0.0003 (6) |
O2' | 0.0386 (6) | 0.0325 (6) | 0.0503 (6) | 0.0047 (4) | 0.0201 (5) | 0.0042 (5) |
C3' | 0.0397 (9) | 0.0509 (12) | 0.0605 (10) | 0.0130 (7) | 0.0158 (8) | 0.0001 (8) |
C4' | 0.0353 (8) | 0.0621 (12) | 0.0538 (10) | 0.0120 (8) | 0.0021 (7) | −0.0015 (9) |
C5' | 0.0502 (9) | 0.0395 (10) | 0.0411 (9) | 0.0112 (7) | 0.0064 (7) | 0.0069 (7) |
C6' | 0.0480 (9) | 0.0450 (10) | 0.0329 (7) | 0.0004 (7) | 0.0072 (6) | 0.0001 (7) |
C7' | 0.0347 (7) | 0.0321 (9) | 0.0353 (7) | −0.0039 (6) | 0.0130 (6) | 0.0006 (6) |
C8' | 0.0336 (7) | 0.0448 (9) | 0.0339 (7) | −0.0031 (6) | 0.0110 (6) | −0.0030 (7) |
C1 | 0.0659 (12) | 0.0386 (10) | 0.0554 (10) | 0.0020 (8) | 0.0355 (9) | −0.0072 (8) |
O1 | 0.0622 (8) | 0.0432 (8) | 0.0764 (9) | 0.0032 (6) | 0.0425 (7) | 0.0000 (6) |
C2 | 0.0575 (10) | 0.0404 (10) | 0.0482 (9) | −0.0036 (7) | 0.0286 (8) | −0.0070 (7) |
C3 | 0.0646 (12) | 0.124 (2) | 0.0445 (10) | −0.0364 (13) | 0.0251 (9) | −0.0349 (12) |
C4 | 0.0954 (18) | 0.154 (3) | 0.0467 (12) | −0.0386 (18) | 0.0274 (12) | −0.0288 (14) |
C5 | 0.0872 (16) | 0.110 (2) | 0.0481 (11) | −0.0068 (14) | 0.0300 (11) | −0.0007 (12) |
C6A | 0.046 (2) | 0.068 (3) | 0.060 (2) | −0.013 (2) | −0.0082 (17) | 0.008 (2) |
C7A | 0.041 (2) | 0.078 (3) | 0.065 (2) | −0.001 (2) | −0.0053 (17) | −0.006 (2) |
C8A | 0.055 (4) | 0.073 (4) | 0.127 (5) | −0.004 (3) | −0.036 (4) | −0.019 (3) |
C6B | 0.040 (2) | 0.068 (3) | 0.037 (2) | 0.003 (2) | 0.0019 (17) | −0.004 (2) |
C7B | 0.060 (4) | 0.057 (4) | 0.072 (3) | −0.001 (3) | −0.005 (3) | 0.007 (3) |
C8B | 0.085 (8) | 0.092 (6) | 0.143 (7) | 0.016 (7) | −0.061 (8) | −0.025 (5) |
C10 | 0.0565 (10) | 0.0560 (12) | 0.0594 (11) | −0.0118 (9) | 0.0327 (8) | 0.0016 (9) |
C9 | 0.0558 (10) | 0.0582 (12) | 0.0549 (10) | 0.0148 (9) | 0.0230 (8) | 0.0090 (9) |
C11 | 0.0653 (12) | 0.0505 (12) | 0.0579 (11) | −0.0055 (9) | 0.0242 (9) | −0.0147 (9) |
Si1—C9 | 1.8655 (18) | C7'—C8' | 1.534 (2) |
Si1—C10 | 1.8671 (17) | C1—O1 | 1.213 (2) |
Si1—C11 | 1.8704 (18) | C1—C5 | 1.489 (3) |
Si1—C7' | 1.8788 (15) | C1—C2 | 1.526 (2) |
C1'—C8' | 1.542 (2) | C2—C3 | 1.525 (3) |
C1'—C5' | 1.553 (2) | C3—C6B | 1.473 (4) |
C1'—C2' | 1.553 (2) | C3—C4 | 1.540 (3) |
C2'—O2' | 1.4321 (19) | C3—C6A | 1.643 (5) |
C2'—C3' | 1.531 (2) | C4—C5 | 1.504 (3) |
C2'—C2 | 1.542 (2) | C6A—C7A | 1.490 (5) |
C3'—C4' | 1.519 (3) | C7A—C8A | 1.283 (10) |
C4'—C5' | 1.527 (2) | C6B—C7B | 1.477 (8) |
C5'—C6' | 1.532 (2) | C7B—C8B | 1.283 (12) |
C6'—C7' | 1.535 (2) | ||
C9—Si1—C10 | 108.67 (9) | C8'—C7'—Si1 | 114.12 (10) |
C9—Si1—C11 | 110.32 (10) | C6'—C7'—Si1 | 115.75 (10) |
C10—Si1—C11 | 108.77 (9) | C7'—C8'—C1' | 106.05 (12) |
C9—Si1—C7' | 109.15 (7) | O1—C1—C5 | 125.48 (16) |
C10—Si1—C7' | 110.34 (8) | O1—C1—C2 | 124.78 (17) |
C11—Si1—C7' | 109.58 (8) | C5—C1—C2 | 109.74 (16) |
C8'—C1'—C5' | 105.61 (12) | C3—C2—C1 | 104.47 (15) |
C8'—C1'—C2' | 116.47 (13) | C3—C2—C2' | 116.79 (14) |
C5'—C1'—C2' | 106.28 (12) | C1—C2—C2' | 111.70 (14) |
O2'—C2'—C3' | 109.93 (13) | C6B—C3—C2 | 136.3 (3) |
O2'—C2'—C2 | 108.79 (13) | C6B—C3—C4 | 110.6 (2) |
C3'—C2'—C2 | 113.90 (13) | C2—C3—C4 | 105.16 (16) |
O2'—C2'—C1' | 107.60 (11) | C6B—C3—C6A | 37.8 (2) |
C3'—C2'—C1' | 102.86 (13) | C2—C3—C6A | 105.0 (2) |
C2—C2'—C1' | 113.49 (13) | C4—C3—C6A | 112.5 (2) |
C4'—C3'—C2' | 102.68 (12) | C5—C4—C3 | 104.71 (17) |
C3'—C4'—C5' | 103.52 (14) | C1—C5—C4 | 104.56 (19) |
C4'—C5'—C6' | 116.04 (15) | C7A—C6A—C3 | 109.4 (3) |
C4'—C5'—C1' | 104.74 (12) | C8A—C7A—C6A | 126.8 (5) |
C6'—C5'—C1' | 106.00 (12) | C3—C6B—C7B | 104.7 (4) |
C5'—C6'—C7' | 105.08 (12) | C8B—C7B—C6B | 125.9 (8) |
C8'—C7'—C6' | 102.49 (12) | ||
C8'—C1'—C2'—O2' | 22.39 (17) | O1—C1—C2—C3 | 179.07 (18) |
C5'—C1'—C2'—O2' | −94.91 (14) | C5—C1—C2—C3 | −0.5 (2) |
C8'—C1'—C2'—C3' | 138.44 (14) | O1—C1—C2—C2' | 51.9 (2) |
C5'—C1'—C2'—C3' | 21.14 (16) | C5—C1—C2—C2' | −127.60 (18) |
C8'—C1'—C2'—C2 | −98.03 (16) | O2'—C2'—C2—C3 | −64.13 (19) |
C5'—C1'—C2'—C2 | 144.67 (13) | C3'—C2'—C2—C3 | 172.87 (17) |
O2'—C2'—C3'—C4' | 74.06 (16) | C1'—C2'—C2—C3 | 55.6 (2) |
C2—C2'—C3'—C4' | −163.56 (14) | O2'—C2'—C2—C1 | 56.02 (17) |
C1'—C2'—C3'—C4' | −40.31 (17) | C3'—C2'—C2—C1 | −66.97 (19) |
C2'—C3'—C4'—C5' | 44.70 (17) | C1'—C2'—C2—C1 | 175.76 (14) |
C3'—C4'—C5'—C6' | −147.30 (14) | C1—C2—C3—C6B | 164.6 (3) |
C3'—C4'—C5'—C1' | −30.83 (17) | C2'—C2—C3—C6B | −71.5 (4) |
C8'—C1'—C5'—C4' | −118.56 (14) | C1—C2—C3—C4 | 20.3 (3) |
C2'—C1'—C5'—C4' | 5.76 (17) | C2'—C2—C3—C4 | 144.2 (2) |
C8'—C1'—C5'—C6' | 4.65 (17) | C1—C2—C3—C6A | 139.2 (2) |
C2'—C1'—C5'—C6' | 128.97 (14) | C2'—C2—C3—C6A | −96.9 (3) |
C4'—C5'—C6'—C7' | 89.10 (16) | C6B—C3—C4—C5 | 172.5 (3) |
C1'—C5'—C6'—C7' | −26.67 (17) | C2—C3—C4—C5 | −33.0 (3) |
C5'—C6'—C7'—C8' | 38.13 (15) | C6A—C3—C4—C5 | −146.7 (3) |
C5'—C6'—C7'—Si1 | 162.99 (11) | O1—C1—C5—C4 | 160.5 (2) |
C9—Si1—C7'—C8' | −60.63 (13) | C2—C1—C5—C4 | −20.0 (3) |
C10—Si1—C7'—C8' | 58.71 (13) | C3—C4—C5—C1 | 32.3 (3) |
C11—Si1—C7'—C8' | 178.45 (11) | C6B—C3—C6A—C7A | 35.7 (3) |
C9—Si1—C7'—C6' | −179.26 (12) | C2—C3—C6A—C7A | −173.2 (3) |
C10—Si1—C7'—C6' | −59.91 (13) | C4—C3—C6A—C7A | −59.4 (4) |
C11—Si1—C7'—C6' | 59.83 (14) | C3—C6A—C7A—C8A | 129.1 (9) |
C6'—C7'—C8'—C1' | −35.28 (14) | C2—C3—C6B—C7B | −71.7 (4) |
Si1—C7'—C8'—C1' | −161.20 (10) | C4—C3—C6B—C7B | 71.3 (4) |
C5'—C1'—C8'—C7' | 19.13 (16) | C6A—C3—C6B—C7B | −29.1 (3) |
C2'—C1'—C8'—C7' | −98.54 (14) | C3—C6B—C7B—C8B | −128.7 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2′—H2′···O1i | 0.83 | 2.04 | 2.8605 (16) | 168 |
Symmetry code: (i) −x+2, −y+1, −z. |
Experimental details
Crystal data | |
Chemical formula | C19H32O2Si |
Mr | 320.54 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 223 |
a, b, c (Å) | 14.1445 (14), 6.2718 (4), 22.340 (2) |
β (°) | 103.694 (11) |
V (Å3) | 1925.4 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.13 |
Crystal size (mm) | 0.45 × 0.40 × 0.30 |
Data collection | |
Diffractometer | Stoe IPDS diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13376, 3691, 2809 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.614 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.115, 1.05 |
No. of reflections | 3691 |
No. of parameters | 231 |
No. of restraints | 6 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.31, −0.29 |
Computer programs: EXPOSE in IPDS Software (Stoe & Cie, 2000), CELL in IPDS Software, INTEGRATE in IPDS Software, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), PLATON99 (Spek, 1990), SHELXL97.
D—H···A | D—H | H···A | D···A | D—H···A |
O2'—H2'···O1i | 0.83 | 2.04 | 2.8605 (16) | 167.7 |
Symmetry code: (i) −x+2, −y+1, −z. |
In the context of a project described elsewere (Helbling et al., 1999), we investigated the allylation of cyclopentenone (1) with allyltrimethylsilane (2) (Hosomi & Sakurai, 1977). Careful chromatography of the product mixture gave the aldol product rel-(2R,3S,1'R,2'S,5'S,7'S)-3-allyl-2-(2'-hydroxy-7'- trimethylsilylbicyclo[3.3.0]octan-2'-yl)cyclopentanone, (3). In order to determine the stereochemistry of the trimethylsilyl group in (3) and other structural features, its structure was determined by X-ray diffraction.
The distance between the bridgehead atoms 1' and 5' is 1.553 (2) Å and thus in the normal range for C—C bonds. The bond angles C8'—C1'—C2' = 116.47 (13)° and C4'—C5'—C6' = 116.04 (15)°, at the bridgeheads of the bicyclic structure are rather large. The torsion angles C2'—C1'—C5'—C4' and C8'—C1'—C5'—C6' are 5.76 (17) and 4.65 (17)°, respectively. The two five-membered rings of the bicyclo[3.3.0]octane subunit adopt an exo/endo envelope conformation (with the TMS group in the exo-envelope ring), while the cyclopentanone ring adopts a twist conformation. The trimethylsilyl substituent is located exo to the bridgehead H atoms and thus shows the normal stereoselectivity of the Sakurai reaction (Helbling et al., 1999). In the crystal, molecules related by a center of symmetry are linked by hydrogen bonds, involving hydroxyl O2' and carbonyl O1, to form dimers.