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In both 9,10-dimethoxy-11-oxatricyclo[6.2.1.0
2,7]undeca-4,9-diene-3,6-diol, C
12H
16O
5, (I), and 5,6-dimethoxy-3,7-dioxatetracyclo[6.4.0.0
2,6.0
4,12]dodec-9-en-11-ol, C
12H
16O
5, (II), the hetero-oxygen-containing five-membered rings have an envelope conformation. The six-membered rings are in a boat conformation in compound (I), and in (II), one is in a half-boat and the other is in a slightly distorted boat conformation. The molecules in both compounds interact through classical hydrogen bonds and C—H
O contacts.
Supporting information
CCDC references: 164687; 164688
Brief details of the preparation of (I) and (II) are given in the Comment. In
order to prevent transformation into (II), (I) was kept in and crystallized
from ethyl acetate. Suitable crystals of (II) were obtained by slow
evaporation from an ethanolic solution.
In spite of the rather poor diffraction quality of (I), which made collecting
Friedel-related reflections useless, the main aim of the work was achieved,
which was to obtain the relevant structural information. H atoms were located
on stereochemical grounds, except those of the hydroxyl groups, and refined as
riding, with an isotropic displacement parameter amounting to 1.5 (for methyl
H atoms) or 1.2 (for the other H atoms) times the value of the equivalent
isotropic displacement parameter of the parent atom.
For both compounds, data collection: CAD-4 Software (Enraf-Nonius,1989); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995). Program(s) used to solve structure: SHELXS86 (Sheldrick, 1985) for (I); SIR92 (Altomare et al., 1993) for (II). For both compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1995). Software used to prepare material for publication: PARST95 (Nardelli, 1995), PLATON (Spek, 1998) and WinGX (Farrugia, 1999) for (I); PARST95 (Nardelli, 1995), PLATON (Spek, 1998), WinGX (Farrugia, 1999) for (II).
(I) 9,10-dimethoxy-11-oxatricyclo[6.2.1.0
2,7]undeca-4,9-diene-3,6-diol
top
Crystal data top
C12H16O5 | Dx = 1.408 Mg m−3 |
Mr = 240.25 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 25 reflections |
a = 8.0796 (4) Å | θ = 10.0–18.4° |
b = 10.1970 (7) Å | µ = 0.11 mm−1 |
c = 13.7534 (9) Å | T = 293 K |
V = 1133.11 (12) Å3 | Irregular, colourless |
Z = 4 | 0.20 × 0.10 × 0.05 mm |
F(000) = 512 | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | θmax = 25.5° |
Radiation source: fine-focus sealed tube | h = −9→0 |
Graphite monochromator | k = −12→0 |
ω/2θ scans | l = 0→16 |
1235 measured reflections | 3 standard reflections every 30 min |
1235 independent reflections | intensity decay: 1.0% |
1131 reflections with F2 > 2σF2 | |
Refinement top
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)] = 0.028 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.071 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0386P)2 + 0.2105P] where P = (Fo2 + 2Fc2)/3 |
1235 reflections | (Δ/σ)max < 0.001 |
156 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.12 e Å−3 |
Crystal data top
C12H16O5 | V = 1133.11 (12) Å3 |
Mr = 240.25 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 8.0796 (4) Å | µ = 0.11 mm−1 |
b = 10.1970 (7) Å | T = 293 K |
c = 13.7534 (9) Å | 0.20 × 0.10 × 0.05 mm |
Data collection top
Enraf-Nonius CAD-4 diffractometer | 1131 reflections with F2 > 2σF2 |
1235 measured reflections | 3 standard reflections every 30 min |
1235 independent reflections | intensity decay: 1.0% |
Refinement top
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.071 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.13 e Å−3 |
1235 reflections | Δρmin = −0.12 e Å−3 |
156 parameters | |
Special details top
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 on F2 for ALL reflections. Weighted R-factors
wR and all goodnesses of fit S are based on F2,
conventional R-factors R are based on F, with F
set to zero for negative F2. The observed criterion of F2 >
σ(F2) is used only for calculating R-factor-obs 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.3506 (2) | 0.67628 (13) | 0.90520 (10) | 0.0405 (4) | |
O2 | 0.2964 (2) | 0.84561 (16) | 0.63248 (10) | 0.0475 (4) | |
H2O | 0.2920 | 0.9069 | 0.5802 | 0.057* | |
O3 | 0.04948 (19) | 0.99741 (16) | 0.99053 (11) | 0.0466 (4) | |
H3O | −0.0239 | 0.9414 | 1.0217 | 0.056* | |
O4 | 0.42929 (19) | 0.99291 (15) | 0.99572 (10) | 0.0437 (4) | |
O5 | 0.57015 (19) | 0.94012 (14) | 0.78760 (11) | 0.0417 (4) | |
C1 | 0.3791 (3) | 0.74063 (19) | 0.81226 (14) | 0.0353 (5) | |
H1 | 0.4377 | 0.6869 | 0.7642 | 0.042* | |
C2 | 0.1975 (3) | 0.77429 (19) | 0.78484 (14) | 0.0335 (5) | |
H2 | 0.1428 | 0.6937 | 0.7631 | 0.040* | |
C3 | 0.1784 (3) | 0.8779 (2) | 0.70497 (13) | 0.0364 (5) | |
H3 | 0.0678 | 0.8687 | 0.6766 | 0.044* | |
C4 | 0.1948 (3) | 1.0150 (2) | 0.74374 (15) | 0.0407 (5) | |
H4 | 0.2481 | 1.0783 | 0.7064 | 0.049* | |
C5 | 0.1349 (3) | 1.0474 (2) | 0.82980 (15) | 0.0421 (5) | |
H5 | 0.1467 | 1.1332 | 0.8517 | 0.051* | |
C6 | 0.0491 (3) | 0.9499 (2) | 0.89263 (15) | 0.0381 (5) | |
H6 | −0.0662 | 0.9440 | 0.8710 | 0.046* | |
C7 | 0.1255 (3) | 0.8125 (2) | 0.88593 (14) | 0.0345 (5) | |
H7 | 0.0407 | 0.7481 | 0.9038 | 0.041* | |
C8 | 0.2795 (3) | 0.7905 (2) | 0.95180 (13) | 0.0357 (5) | |
H8 | 0.2535 | 0.7782 | 1.0208 | 0.043* | |
C9 | 0.4108 (3) | 0.89169 (19) | 0.93237 (14) | 0.0334 (4) | |
C10 | 0.4725 (2) | 0.86280 (19) | 0.84497 (13) | 0.0322 (4) | |
C11 | 0.5495 (4) | 1.0897 (3) | 0.97103 (18) | 0.0638 (8) | |
H11A | 0.5468 | 1.1590 | 1.0182 | 0.096* | |
H11B | 0.5252 | 1.1247 | 0.9078 | 0.096* | |
H11C | 0.6575 | 1.0505 | 0.9704 | 0.096* | |
C12 | 0.6722 (3) | 0.8738 (2) | 0.71896 (16) | 0.0475 (6) | |
H12A | 0.6038 | 0.8304 | 0.6718 | 0.071* | |
H12B | 0.7392 | 0.8101 | 0.7521 | 0.071* | |
H12C | 0.7423 | 0.9361 | 0.6867 | 0.071* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0568 (9) | 0.0323 (7) | 0.0325 (7) | 0.0042 (7) | −0.0020 (7) | 0.0081 (6) |
O2 | 0.0607 (10) | 0.0526 (9) | 0.0294 (7) | 0.0118 (9) | 0.0070 (7) | 0.0078 (6) |
O3 | 0.0514 (9) | 0.0510 (10) | 0.0374 (8) | −0.0111 (8) | 0.0095 (7) | −0.0091 (8) |
O4 | 0.0484 (8) | 0.0499 (10) | 0.0329 (7) | −0.0113 (8) | 0.0031 (7) | −0.0096 (8) |
O5 | 0.0456 (8) | 0.0376 (7) | 0.0419 (8) | −0.0002 (7) | 0.0139 (7) | −0.0015 (7) |
C1 | 0.0468 (13) | 0.0318 (10) | 0.0273 (9) | 0.0029 (10) | −0.0006 (9) | 0.0035 (8) |
C2 | 0.0392 (11) | 0.0323 (9) | 0.0290 (9) | −0.0058 (9) | −0.0013 (9) | 0.0000 (8) |
C3 | 0.0358 (10) | 0.0464 (12) | 0.0270 (9) | 0.0045 (10) | −0.0031 (9) | 0.0044 (9) |
C4 | 0.0473 (12) | 0.0380 (10) | 0.0367 (10) | 0.0078 (10) | 0.0033 (10) | 0.0131 (9) |
C5 | 0.0468 (13) | 0.0359 (10) | 0.0437 (11) | 0.0073 (10) | 0.0015 (10) | 0.0039 (9) |
C6 | 0.0344 (11) | 0.0458 (11) | 0.0340 (10) | −0.0002 (10) | 0.0028 (9) | −0.0030 (9) |
C7 | 0.0367 (11) | 0.0374 (10) | 0.0294 (9) | −0.0098 (9) | 0.0017 (9) | 0.0029 (8) |
C8 | 0.0453 (12) | 0.0374 (10) | 0.0245 (8) | 0.0003 (10) | 0.0014 (8) | 0.0058 (8) |
C9 | 0.0349 (10) | 0.0369 (10) | 0.0283 (9) | 0.0015 (9) | −0.0052 (8) | 0.0006 (8) |
C10 | 0.0326 (10) | 0.0330 (9) | 0.0309 (9) | 0.0020 (9) | −0.0012 (8) | 0.0028 (9) |
C11 | 0.080 (2) | 0.0637 (16) | 0.0481 (13) | −0.0316 (16) | 0.0129 (14) | −0.0151 (12) |
C12 | 0.0440 (12) | 0.0519 (13) | 0.0465 (12) | 0.0005 (11) | 0.0117 (11) | −0.0062 (11) |
Geometric parameters (Å, º) top
O1—C8 | 1.448 (2) | C2—C3 | 1.532 (3) |
O1—C1 | 1.455 (2) | C2—C7 | 1.557 (3) |
O2—C3 | 1.418 (2) | C3—C4 | 1.502 (3) |
O3—C6 | 1.431 (2) | C4—C5 | 1.321 (3) |
O4—C9 | 1.359 (2) | C5—C6 | 1.488 (3) |
O4—C11 | 1.426 (3) | C6—C7 | 1.534 (3) |
O5—C10 | 1.366 (2) | C7—C8 | 1.556 (3) |
O5—C12 | 1.424 (3) | C8—C9 | 1.504 (3) |
C1—C10 | 1.524 (3) | C9—C10 | 1.334 (3) |
C1—C2 | 1.554 (3) | | |
| | | |
C8—O1—C1 | 95.09 (13) | O3—C6—C7 | 111.40 (17) |
C9—O4—C11 | 116.61 (16) | C5—C6—C7 | 112.82 (17) |
C10—O5—C12 | 116.29 (16) | C6—C7—C8 | 114.74 (16) |
O1—C1—C10 | 100.82 (14) | C6—C7—C2 | 115.63 (16) |
O1—C1—C2 | 99.41 (15) | C8—C7—C2 | 100.66 (16) |
C10—C1—C2 | 111.03 (16) | O1—C8—C9 | 101.15 (15) |
C3—C2—C1 | 114.91 (17) | O1—C8—C7 | 100.12 (15) |
C3—C2—C7 | 115.49 (16) | C9—C8—C7 | 111.22 (16) |
C1—C2—C7 | 101.04 (15) | C10—C9—O4 | 134.8 (2) |
O2—C3—C4 | 113.99 (19) | C10—C9—C8 | 105.80 (17) |
O2—C3—C2 | 106.04 (16) | O4—C9—C8 | 119.00 (17) |
C4—C3—C2 | 112.25 (16) | C9—C10—O5 | 127.49 (19) |
C5—C4—C3 | 121.2 (2) | C9—C10—C1 | 105.14 (17) |
C4—C5—C6 | 121.6 (2) | O5—C10—C1 | 125.95 (16) |
O3—C6—C5 | 108.64 (17) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12A···O2 | 0.96 | 2.55 | 3.273 (3) | 133 |
O2—H2O···O3i | 0.95 | 2.03 | 2.815 (2) | 139 |
O2—H2O···O4i | 0.95 | 2.36 | 3.094 (2) | 133 |
O3—H3O···O1ii | 0.93 | 1.87 | 2.788 (2) | 173 |
C1—H1···O5iii | 0.98 | 2.62 | 3.383 (2) | 135 |
Symmetry codes: (i) −x+1/2, −y+2, z−1/2; (ii) x−1/2, −y+3/2, −z+2; (iii) −x+1, y−1/2, −z+3/2. |
(II) 5,6-dimethoxy-3,7-dioxatetracyclo[6.4.0.0
2,60
4,12]dodec-9-en-11-ol
top
Crystal data top
C12H16O5 | F(000) = 1024.0 |
Mr = 240.25 | Dx = 1.444 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 7.545 (1) Å | Cell parameters from 25 reflections |
b = 10.750 (1) Å | θ = 9.9–18.2° |
c = 27.336 (3) Å | µ = 0.11 mm−1 |
β = 94.69 (2)° | T = 293 K |
V = 2209.8 (4) Å3 | Irregular, colourless |
Z = 8 | 0.25 × 0.20 × 0.16 mm |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.026 |
Radiation source: fine-focus sealed tube | θmax = 25.5° |
Graphite monochromator | h = −7→9 |
ω/2θ scans | k = −7→12 |
4326 measured reflections | l = −33→33 |
2038 independent reflections | 3 standard reflections every 30 min |
1513 reflections with F2 > 2σF2 | intensity decay: 1.1% |
Refinement top
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)] = 0.040 | Hydrogen site location: mixed |
wR(F2) = 0.100 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0465P)2 + 1.8597P] where P = (Fo2 + 2Fc2)/3 |
2038 reflections | (Δ/σ)max < 0.001 |
156 parameters | Δρmax = 0.19 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
Crystal data top
C12H16O5 | V = 2209.8 (4) Å3 |
Mr = 240.25 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 7.545 (1) Å | µ = 0.11 mm−1 |
b = 10.750 (1) Å | T = 293 K |
c = 27.336 (3) Å | 0.25 × 0.20 × 0.16 mm |
β = 94.69 (2)° | |
Data collection top
Enraf-Nonius CAD-4 diffractometer | Rint = 0.026 |
4326 measured reflections | 3 standard reflections every 30 min |
2038 independent reflections | intensity decay: 1.1% |
1513 reflections with F2 > 2σF2 | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.100 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.19 e Å−3 |
2038 reflections | Δρmin = −0.21 e Å−3 |
156 parameters | |
Special details top
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 on F2 for ALL reflections. Weighted R-factors
wR and all goodnesses of fit S are based on F2,
conventional R-factors R are based on F, with F
set to zero for negative F2. The observed criterion of F2 >
σ(F2) is used only for calculating R-factor-obs 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.5145 (2) | 0.37746 (15) | 0.12294 (6) | 0.0487 (4) | |
O2 | 0.40985 (17) | 0.06233 (14) | 0.11975 (5) | 0.0384 (4) | |
O3 | 0.96747 (18) | 0.16362 (17) | 0.17533 (6) | 0.0534 (5) | |
H3O | 0.9372 | 0.1178 | 0.1411 | 0.064* | |
O4 | 0.32909 (16) | 0.17881 (16) | 0.05138 (5) | 0.0432 (4) | |
O5 | 0.74248 (17) | 0.10451 (15) | 0.08970 (5) | 0.0416 (4) | |
C1 | 0.4723 (2) | 0.2171 (2) | 0.18084 (7) | 0.0382 (5) | |
H1 | 0.4188 | 0.2488 | 0.2098 | 0.046* | |
C2 | 0.3940 (3) | 0.2797 (2) | 0.13359 (7) | 0.0409 (5) | |
H2 | 0.2692 | 0.3049 | 0.1337 | 0.049* | |
C4 | 0.6745 (3) | 0.3031 (2) | 0.12733 (8) | 0.0426 (5) | |
H4 | 0.7819 | 0.3506 | 0.1219 | 0.051* | |
C5 | 0.6264 (2) | 0.2071 (2) | 0.08736 (7) | 0.0375 (5) | |
H5 | 0.6294 | 0.2471 | 0.0552 | 0.045* | |
C6 | 0.4300 (2) | 0.1778 (2) | 0.09652 (7) | 0.0354 (5) | |
C8 | 0.4345 (3) | 0.0799 (2) | 0.17260 (7) | 0.0379 (5) | |
H8 | 0.3237 | 0.0585 | 0.1870 | 0.046* | |
C9 | 0.5782 (3) | −0.0054 (2) | 0.19291 (7) | 0.0420 (5) | |
H9 | 0.5506 | −0.0887 | 0.1974 | 0.050* | |
C10 | 0.7427 (3) | 0.0320 (2) | 0.20482 (7) | 0.0441 (5) | |
H10 | 0.8241 | −0.0281 | 0.2166 | 0.053* | |
C11 | 0.8095 (3) | 0.1612 (2) | 0.20115 (7) | 0.0427 (5) | |
H11 | 0.8453 | 0.1878 | 0.2348 | 0.051* | |
C12 | 0.6707 (3) | 0.2561 (2) | 0.18038 (7) | 0.0400 (5) | |
H12 | 0.6857 | 0.3297 | 0.2014 | 0.048* | |
C13 | 0.7111 (3) | 0.0236 (3) | 0.04885 (8) | 0.0539 (6) | |
H13A | 0.7997 | −0.0407 | 0.0505 | 0.081* | |
H13B | 0.7169 | 0.0700 | 0.0190 | 0.081* | |
H13C | 0.5953 | −0.0132 | 0.0494 | 0.081* | |
C14 | 0.1424 (3) | 0.1584 (3) | 0.05426 (8) | 0.0519 (6) | |
H14A | 0.0831 | 0.1598 | 0.0218 | 0.078* | |
H14B | 0.0949 | 0.2228 | 0.0737 | 0.078* | |
H14C | 0.1244 | 0.0791 | 0.0692 | 0.078* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0493 (9) | 0.0391 (9) | 0.0568 (9) | 0.0008 (7) | −0.0013 (7) | 0.0039 (7) |
O2 | 0.0425 (8) | 0.0446 (9) | 0.0275 (7) | −0.0091 (7) | −0.0008 (5) | 0.0011 (6) |
O3 | 0.0306 (7) | 0.0782 (13) | 0.0509 (9) | −0.0031 (8) | 0.0001 (6) | −0.0055 (8) |
O4 | 0.0293 (7) | 0.0698 (11) | 0.0298 (7) | −0.0035 (7) | −0.0028 (5) | 0.0050 (7) |
O5 | 0.0311 (7) | 0.0576 (10) | 0.0353 (7) | 0.0040 (7) | −0.0015 (5) | −0.0042 (7) |
C1 | 0.0343 (10) | 0.0497 (13) | 0.0304 (10) | 0.0031 (9) | 0.0023 (8) | −0.0057 (9) |
C2 | 0.0339 (10) | 0.0476 (14) | 0.0410 (11) | 0.0034 (9) | 0.0021 (8) | −0.0002 (10) |
C4 | 0.0347 (10) | 0.0444 (13) | 0.0477 (12) | −0.0075 (9) | −0.0022 (8) | 0.0029 (10) |
C5 | 0.0311 (10) | 0.0489 (13) | 0.0323 (10) | −0.0024 (9) | 0.0016 (7) | 0.0064 (9) |
C6 | 0.0294 (9) | 0.0469 (13) | 0.0292 (9) | −0.0019 (9) | −0.0019 (7) | 0.0055 (9) |
C8 | 0.0345 (10) | 0.0521 (14) | 0.0273 (9) | −0.0042 (9) | 0.0031 (7) | 0.0017 (9) |
C9 | 0.0474 (12) | 0.0442 (13) | 0.0344 (10) | −0.0013 (10) | 0.0029 (8) | 0.0078 (9) |
C10 | 0.0449 (12) | 0.0539 (15) | 0.0326 (10) | 0.0095 (10) | −0.0029 (8) | 0.0041 (10) |
C11 | 0.0350 (10) | 0.0599 (15) | 0.0319 (10) | 0.0020 (10) | −0.0046 (8) | −0.0071 (10) |
C12 | 0.0384 (10) | 0.0423 (13) | 0.0384 (11) | −0.0029 (9) | −0.0025 (8) | −0.0101 (9) |
C13 | 0.0531 (13) | 0.0686 (18) | 0.0393 (12) | 0.0112 (12) | −0.0012 (9) | −0.0111 (12) |
C14 | 0.0316 (10) | 0.0800 (19) | 0.0427 (12) | −0.0059 (11) | −0.0053 (9) | 0.0036 (12) |
Geometric parameters (Å, º) top
O1—C2 | 1.435 (3) | C1—C2 | 1.531 (3) |
O1—C4 | 1.444 (3) | C1—C12 | 1.555 (3) |
O2—C6 | 1.408 (2) | C2—C6 | 1.532 (3) |
O2—C8 | 1.454 (2) | C4—C5 | 1.525 (3) |
O3—C11 | 1.434 (2) | C4—C12 | 1.538 (3) |
O4—C6 | 1.396 (2) | C5—C6 | 1.555 (2) |
O4—C14 | 1.434 (2) | C8—C9 | 1.492 (3) |
O5—C5 | 1.406 (3) | C9—C10 | 1.319 (3) |
O5—C13 | 1.420 (3) | C10—C11 | 1.483 (3) |
C1—C8 | 1.516 (3) | C11—C12 | 1.537 (3) |
| | | |
C2—O1—C4 | 96.72 (15) | O4—C6—C2 | 117.74 (17) |
C6—O2—C8 | 108.91 (15) | O2—C6—C2 | 107.49 (15) |
C6—O4—C14 | 114.67 (15) | O4—C6—C5 | 108.31 (15) |
C5—O5—C13 | 112.42 (15) | O2—C6—C5 | 113.01 (16) |
C8—C1—C2 | 104.31 (16) | C2—C6—C5 | 100.63 (16) |
C8—C1—C12 | 115.46 (17) | O2—C8—C9 | 108.69 (16) |
C2—C1—C12 | 100.39 (16) | O2—C8—C1 | 106.33 (16) |
O1—C2—C1 | 106.58 (16) | C9—C8—C1 | 114.86 (16) |
O1—C2—C6 | 103.88 (16) | C10—C9—C8 | 123.0 (2) |
C1—C2—C6 | 99.60 (17) | C9—C10—C11 | 125.9 (2) |
O1—C4—C5 | 99.60 (15) | O3—C11—C10 | 110.56 (18) |
O1—C4—C12 | 100.40 (16) | O3—C11—C12 | 111.99 (18) |
C5—C4—C12 | 115.55 (18) | C10—C11—C12 | 114.92 (17) |
O5—C5—C4 | 112.80 (15) | C11—C12—C4 | 120.12 (17) |
O5—C5—C6 | 115.55 (17) | C11—C12—C1 | 116.46 (18) |
C4—C5—C6 | 101.29 (16) | C4—C12—C1 | 100.85 (15) |
O4—C6—O2 | 109.54 (16) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3O···O5 | 1.06 | 1.95 | 2.849 (2) | 140 |
C13—H13C···O2 | 0.96 | 2.60 | 3.133 (3) | 115 |
C13—H13A···O1i | 0.96 | 2.61 | 3.325 (3) | 132 |
C4—H4···O2ii | 0.98 | 2.47 | 3.320 (3) | 144 |
C11—H11···O3iii | 0.98 | 2.74 | 3.648 (3) | 154 |
Symmetry codes: (i) x+1/2, y−1/2, z; (ii) x+1/2, y+1/2, z; (iii) −x+2, y, −z+1/2. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C12H16O5 | C12H16O5 |
Mr | 240.25 | 240.25 |
Crystal system, space group | Orthorhombic, P212121 | Monoclinic, C2/c |
Temperature (K) | 293 | 293 |
a, b, c (Å) | 8.0796 (4), 10.1970 (7), 13.7534 (9) | 7.545 (1), 10.750 (1), 27.336 (3) |
α, β, γ (°) | 90, 90, 90 | 90, 94.69 (2), 90 |
V (Å3) | 1133.11 (12) | 2209.8 (4) |
Z | 4 | 8 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.11 | 0.11 |
Crystal size (mm) | 0.20 × 0.10 × 0.05 | 0.25 × 0.20 × 0.16 |
|
Data collection |
Diffractometer | Enraf-Nonius CAD-4 diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | – | – |
No. of measured, independent and observed (F2 > 2σF2) reflections | 1235, 1235, 1131 | 4326, 2038, 1513 |
Rint | ? | 0.026 |
(sin θ/λ)max (Å−1) | 0.605 | 0.606 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.071, 1.05 | 0.040, 0.100, 1.06 |
No. of reflections | 1235 | 2038 |
No. of parameters | 156 | 156 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.12 | 0.19, −0.21 |
Selected geometric parameters (Å, º) for (I) topO1—C8 | 1.448 (2) | O3—C6 | 1.431 (2) |
O1—C1 | 1.455 (2) | C4—C5 | 1.321 (3) |
O2—C3 | 1.418 (2) | C9—C10 | 1.334 (3) |
| | | |
C8—O1—C1 | 95.09 (13) | C5—C4—C3 | 121.2 (2) |
C9—O4—C11 | 116.61 (16) | C4—C5—C6 | 121.6 (2) |
C10—O5—C12 | 116.29 (16) | O1—C8—C9 | 101.15 (15) |
O1—C1—C10 | 100.82 (14) | O1—C8—C7 | 100.12 (15) |
O1—C1—C2 | 99.41 (15) | C9—C8—C7 | 111.22 (16) |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
C12—H12A···O2 | 0.96 | 2.55 | 3.273 (3) | 133 |
O2—H2O···O3i | 0.95 | 2.03 | 2.815 (2) | 139 |
O2—H2O···O4i | 0.95 | 2.36 | 3.094 (2) | 133 |
O3—H3O···O1ii | 0.93 | 1.87 | 2.788 (2) | 173 |
C1—H1···O5iii | 0.98 | 2.62 | 3.383 (2) | 135 |
Symmetry codes: (i) −x+1/2, −y+2, z−1/2; (ii) x−1/2, −y+3/2, −z+2; (iii) −x+1, y−1/2, −z+3/2. |
Cremer & Pople (1975) puckering parameters topRing | | | q2Å | q3Å | ϕ2° | θ2° | QÅ |
O1-C1-C2-C7-C8 | | | 0.614 (2) | | 1.0 (2) | | |
O1-C1-C10-C9-C8 | | | 0.533 (3) | | 179.2 (2) | | |
C1-C2-C7-C8-C9-C10 | | | 0.917 (2) | 0.002 (2) | -1.3 (1) | 89.9 (1) | 0.917 (2) |
C2-C3-C4-C5-C6-C7 | | | 0.496 (2) | -0.010 (2) | -120.7 (2) | 91.1 (3) | 0.497 (2) |
Selected geometric parameters (Å, º) for (II) topO1—C2 | 1.435 (3) | O2—C8 | 1.454 (2) |
O1—C4 | 1.444 (3) | C9—C10 | 1.319 (3) |
O2—C6 | 1.408 (2) | | |
| | | |
C2—O1—C4 | 96.72 (15) | C1—C2—C6 | 99.60 (17) |
C6—O2—C8 | 108.91 (15) | O1—C4—C5 | 99.60 (15) |
C6—O4—C14 | 114.67 (15) | O1—C4—C12 | 100.40 (16) |
C5—O5—C13 | 112.42 (15) | C5—C4—C12 | 115.55 (18) |
O1—C2—C1 | 106.58 (16) | C10—C9—C8 | 123.0 (2) |
O1—C2—C6 | 103.88 (16) | C9—C10—C11 | 125.9 (2) |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3O···O5 | 1.06 | 1.95 | 2.849 (2) | 140 |
C13—H13C···O2 | 0.96 | 2.60 | 3.133 (3) | 115 |
C13—H13A···O1i | 0.96 | 2.61 | 3.325 (3) | 132 |
C4—H4···O2ii | 0.98 | 2.47 | 3.320 (3) | 144 |
C11—H11···O3iii | 0.98 | 2.74 | 3.648 (3) | 154 |
Symmetry codes: (i) x+1/2, y−1/2, z; (ii) x+1/2, y+1/2, z; (iii) −x+2, y, −z+1/2. |
Cremer & Pople (1975) puckering parameters topRing | | | q2Å | q3Å | ϕ2° | θ2° | QÅ |
O1-C2-C1-C12-C4 | | | 0.549 (2) | | 164.4 (2) | | |
O1-C2-C6-C5-C4 | | | 0.568 (2) | | -10.4 (2) | | |
C1-C2-C6-O2-C8 | | | 0.357 (2) | | 34.7 (3) | | |
C1-C2-C6-C5-C4-C12 | | | 0.978 (2) | -0.133 (2) | -121.7 (1) | 97.8 (1) | 0.987 (2) |
C1-C8-C9-C10-C11-C12 | | | 0.225 (2) | -0.179 (2) | -179.0 (5) | 128.6 (4) | 0.288 (2) |
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Heliangolides are interesting natural products containing a polymacrocyclic structure (da Costa et al., 1993). Our investigation, aimed at the synthesis of these macrocyclic structures, started with the Diels-Alder reaction between 3,4-dimethoxyfuran and benzoquinone in benzene. The product, (III), was further reduced with sodium borohydride in the presence of ceric chloride to give (I). Due to the cage-like structure of (III), which should prevent the approach of the reagent to the concave face of the substrate, a very high stereoselectivity is expected. In fact, only one product was isolated. We noticed that compound (I) was converted into a different crystalline product, which could be (II) or (IV), within a few hours when kept in chloroform at room temperature. This unexpected result prompted us to proceed with detailed X-ray crystal structure determinations of (I) and of the other product, which was identified as (II). \sch
In order to establish possible changes in the conformations of and distances between the functional groups in the molecules, when released from interactions with surrounding molecules in the crystalline state, a series of semi-empirical (AM1 and PM3) and ab initio quantum chemistry calculations were performed. This study should help in postulating a mechanism for the transformation of (I) into (II). The calculations were carried out using the 6–31G** basis set of the MOPAC7.01 (Stewart, 1990; Csern, 2000) and GAMESS98 (Schmidt et al., 1993) packages.
The molecular structure of (I) is shown in Fig. 1. Table 3 shows the Cremer & Pople (1975) puckering parameters. As in other norbornenes (Zukerman-Schpector et al., 1999), the six-membered ring (C1, C2 and C7—C10) is in a boat conformation. The `boat' is almost symmetric, with a dihedral angle between the planes defined by C1/O1/C8 and C2/C7/C9/C10 of 86.4 (1)°, and with equal deviations of C8 and C1 from the C2/C7/C9/C10 plane of 0.794 (3) Å, the deviations of O4 and O5 from the C2/C7/C9/C10 plane being 0.598 (3) and 0.812 (3) Å, respectively. The two hetero-oxygen five-membered rings have envelope conformations, with O1 displaced 0.867 (2) Å from the C1/C2/C7/C8 plane and 0.787 (3) Å from the C1/C8/C9/C10 plane. The C2—C7 six-membered ring is also in a boat conformation, making dihedral angles of 11.1 (1)° with the C1—O1—C8 bridge and of 75.29 (8)° with the C2/C7/C9/C10 plane.
The molecular diagram of (II) is shown in Fig. 2. Table 6 shows the Cremer & Pople (1975) puckering parameters. The ring formed by atoms C1, C2, C6, C5, C4 and C12 adopts a slightly distorted boat, towards a half-boat, conformation, which is imposed by O1 bridging C2 and C4. Atoms C2 and C4 deviate from the plane defined by C1/C6/C5/C12 [planar to within 0.015 (1) Å] by 0.971 (3) and 0.712 (3) Å, respectively. The C1,C8—C12 ring is in a half-boat conformation, making dihedral angles of 18.51 (8), 88.78 (7) and 71.94 (8)° with the C2/O1/C4, C1/C6/C5/C12 and C1/C2/C6/O2/C8 planes, respectively. The three hetero-oxygen five-membered rings have envelope conformations, as shown in Table 3, with O1 displaced 0.804 (3) Å from the C1/C2/C4/C12 plane and 0.771 (3) Å from the C2/C4/C5/C6 plane, and C2 displaced 0.564 (3) Å from the C1/C8/O2/C6 plane.
In Tables 2 and 5 is shown that in (I), molecules are linked by several classical hydrogen bonds and a short C—H···O interaction, while in (II), the molecules are linked only by C—H···O short interactions. In both cases, these might be described as hydrogen-bonding interactions. However, as pointed out by Cotton et al. (1997), `the field is getting muddier and muddier as the definition of a hydrogen bond is relaxed'. Therefore, we only choose those with a C—H···O angle greater than 100° and an H···O distance of up to 2.73 Å, which corresponds to the sum of the van der Waals radii of O and H, as given by Pauling (1960), plus 5%.
The geometry optimization calculations on (I), using the three methods (AM1, PM3 and ab initio), showed three main conformational changes. Firstly, the C2—C3—O2—H2O torsion angle changes from 180 to 71°, to give an H2O···O5 distance of 2.28 Å (less than the sum of the van der Waals radii). It should be noted that in the crystal this OH moiety is involved in an intermolecular hydrogen bond (Table 2). Secondly, the C13—O5—C10—C1 torsion angle changes from 39.9 (3) to 71.1°, to leave space for atom H2O. Thirdly, the H3O—O3—C6—C7 torsion angle changes from 67 to -69°, to give a final H3···O4 distance of 2.33 Å. Recall that in (I) the O3—H3O hydroxyl group is involved in an intermolecular hydrogen bond and in (II) it forms an intramolecular hydrogen bond (Table 5). These results strongly suggest that the transformation of (I) into (II) is by the mechanism shown in Scheme 2.