Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802000971/dn6011sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802000971/dn6011Isup2.hkl |
CCDC reference: 182631
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.004 Å
- R factor = 0.057
- wR factor = 0.127
- Data-to-parameter ratio = 19.3
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
CELLV_02 Alert C The supplied cell volume s.u. differs from that calculated from the cell parameter s.u.'s by > 2 Calculated cell volume su = 14.50 Cell volume su given = 12.00 General Notes
REFLT_03 From the CIF: _diffrn_reflns_theta_max 28.63 From the CIF: _reflns_number_total 6413 Count of symmetry unique reflns 3709 Completeness (_total/calc) 172.90% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 2704 Fraction of Friedel pairs measured 0.729 Are heavy atom types Z>Si present yes Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check
Colourless needle-shaped crystals of (2) were obtained by evaporation of an ethanol solution.
Data collection: DENZO (Otwinowski & Minor, 1997); cell refinement: DENZO; data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: PLATON (Spek, 1990).
C27H35NO7S | F(000) = 552 |
Mr = 517.62 | Dx = 1.264 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: P 2yb | Cell parameters from 12731 reflections |
a = 12.1894 (7) Å | θ = 1.8–28.6° |
b = 8.9921 (3) Å | µ = 0.16 mm−1 |
c = 13.0425 (8) Å | T = 293 K |
β = 107.97 (1)° | Square platelet, colourless |
V = 1359.83 (12) Å3 | 0.42 × 0.41 × 0.32 mm |
Z = 2 |
Nonius KappaCCD diffractometer | 5079 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.082 |
Graphite monochromator | θmax = 28.6°, θmin = 1.8° |
ϕ scans | h = −16→16 |
12731 measured reflections | k = −9→11 |
6413 independent reflections | l = −17→14 |
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)] = 0.057 | H-atom parameters constrained |
wR(F2) = 0.128 | w = 1/[σ2(Fo2) + (0.0502P)2 + 0.2323P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max = 0.004 |
6413 reflections | Δρmax = 0.24 e Å−3 |
332 parameters | Δρmin = −0.26 e Å−3 |
1 restraint | Absolute structure: Flack (1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.03 (8) |
C27H35NO7S | V = 1359.83 (12) Å3 |
Mr = 517.62 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 12.1894 (7) Å | µ = 0.16 mm−1 |
b = 8.9921 (3) Å | T = 293 K |
c = 13.0425 (8) Å | 0.42 × 0.41 × 0.32 mm |
β = 107.97 (1)° |
Nonius KappaCCD diffractometer | 5079 reflections with I > 2σ(I) |
12731 measured reflections | Rint = 0.082 |
6413 independent reflections |
R[F2 > 2σ(F2)] = 0.057 | H-atom parameters constrained |
wR(F2) = 0.128 | Δρmax = 0.24 e Å−3 |
S = 1.02 | Δρmin = −0.26 e Å−3 |
6413 reflections | Absolute structure: Flack (1983) |
332 parameters | Absolute structure parameter: 0.03 (8) |
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 | ||
C1 | 0.7590 (4) | 0.1820 (4) | 1.4594 (3) | 0.0781 (10) | |
H11 | 0.8051 | 0.1340 | 1.5241 | 0.117* | |
H12 | 0.7509 | 0.1171 | 1.3990 | 0.117* | |
H13 | 0.6843 | 0.2041 | 1.4655 | 0.117* | |
O2 | 0.8136 (2) | 0.3163 (2) | 1.44387 (15) | 0.0653 (6) | |
C3 | 0.7637 (2) | 0.3942 (3) | 1.3503 (2) | 0.0457 (6) | |
C4 | 0.6625 (2) | 0.3525 (3) | 1.2732 (2) | 0.0510 (6) | |
H4 | 0.6225 | 0.2686 | 1.2834 | 0.061* | |
C5 | 0.6213 (2) | 0.4367 (3) | 1.1809 (2) | 0.0484 (6) | |
H5 | 0.5530 | 0.4086 | 1.1293 | 0.058* | |
C6 | 0.6791 (2) | 0.5623 (3) | 1.16288 (18) | 0.0379 (5) | |
C7 | 0.7792 (2) | 0.6033 (3) | 1.24264 (18) | 0.0439 (5) | |
H7 | 0.8188 | 0.6880 | 1.2333 | 0.053* | |
C8 | 0.8210 (2) | 0.5204 (3) | 1.3355 (2) | 0.0481 (6) | |
H8 | 0.8881 | 0.5498 | 1.3882 | 0.058* | |
C9 | 0.63195 (19) | 0.6522 (3) | 1.06160 (19) | 0.0394 (5) | |
H9 | 0.6752 | 0.7454 | 1.0678 | 0.047* | |
O10 | 0.51034 (15) | 0.6846 (2) | 1.04801 (14) | 0.0470 (4) | |
C11 | 0.4443 (2) | 0.6078 (3) | 0.96175 (19) | 0.0420 (5) | |
C12 | 0.5040 (2) | 0.5381 (3) | 0.90532 (19) | 0.0392 (5) | |
C13 | 0.63085 (19) | 0.5694 (3) | 0.95591 (17) | 0.0376 (5) | |
H13A | 0.6753 | 0.4769 | 0.9722 | 0.045* | |
C14 | 0.3192 (2) | 0.6127 (4) | 0.9489 (2) | 0.0584 (7) | |
H141 | 0.2770 | 0.5668 | 0.8819 | 0.088* | |
H142 | 0.2951 | 0.7143 | 0.9491 | 0.088* | |
H143 | 0.3045 | 0.5602 | 1.0075 | 0.088* | |
C15 | 0.4544 (2) | 0.4485 (3) | 0.8094 (2) | 0.0445 (6) | |
O16 | 0.35240 (17) | 0.4308 (2) | 0.76475 (16) | 0.0591 (5) | |
O17 | 0.53765 (17) | 0.3865 (2) | 0.77539 (15) | 0.0531 (5) | |
C18 | 0.5000 (3) | 0.2781 (4) | 0.6872 (3) | 0.0692 (9) | |
H18 | 0.4252 | 0.2365 | 0.6853 | 0.083* | |
C19 | 0.5884 (4) | 0.1573 (4) | 0.7100 (3) | 0.0850 (11) | |
H191 | 0.5652 | 0.0823 | 0.6551 | 0.127* | |
H192 | 0.5955 | 0.1139 | 0.7790 | 0.127* | |
H193 | 0.6614 | 0.1981 | 0.7105 | 0.127* | |
C20 | 0.4884 (4) | 0.3609 (6) | 0.5824 (3) | 0.1016 (15) | |
H201 | 0.4633 | 0.2931 | 0.5229 | 0.152* | |
H202 | 0.5617 | 0.4024 | 0.5847 | 0.152* | |
H203 | 0.4328 | 0.4393 | 0.5736 | 0.152* | |
C21 | 0.6740 (2) | 0.6690 (3) | 0.8817 (2) | 0.0409 (5) | |
O22 | 0.61499 (17) | 0.7664 (2) | 0.82772 (19) | 0.0686 (6) | |
N23 | 0.78244 (15) | 0.6416 (2) | 0.87213 (15) | 0.0370 (4) | |
C24 | 0.8229 (2) | 0.7316 (3) | 0.79590 (19) | 0.0404 (5) | |
H24 | 0.8301 | 0.8365 | 0.8174 | 0.048* | |
C25 | 0.9417 (2) | 0.6670 (3) | 0.79914 (19) | 0.0427 (5) | |
C26 | 1.0019 (2) | 0.6112 (4) | 0.9126 (2) | 0.0498 (6) | |
H26A | 1.0593 | 0.6826 | 0.9517 | 0.060* | |
H26B | 1.0402 | 0.5173 | 0.9101 | 0.060* | |
S27 | 0.89428 (5) | 0.58802 (9) | 0.97727 (5) | 0.05254 (19) | |
O28 | 0.87975 (19) | 0.4366 (3) | 1.0018 (2) | 0.0932 (10) | |
O29 | 0.9098 (2) | 0.6926 (4) | 1.06203 (17) | 0.0987 (11) | |
C30 | 0.7503 (2) | 0.7154 (4) | 0.6769 (2) | 0.0568 (7) | |
H30A | 0.6899 | 0.6418 | 0.6680 | 0.068* | |
H30B | 0.7160 | 0.8094 | 0.6471 | 0.068* | |
C31 | 0.8406 (2) | 0.6640 (4) | 0.6247 (2) | 0.0598 (7) | |
H31 | 0.8078 | 0.6242 | 0.5517 | 0.072* | |
C32 | 0.9268 (3) | 0.7925 (5) | 0.6332 (2) | 0.0721 (9) | |
H32A | 0.8869 | 0.8866 | 0.6136 | 0.086* | |
H32B | 0.9747 | 0.7749 | 0.5873 | 0.086* | |
C33 | 0.9996 (2) | 0.7909 (4) | 0.7538 (2) | 0.0579 (7) | |
H33A | 1.0797 | 0.7677 | 0.7627 | 0.070* | |
H33B | 0.9953 | 0.8855 | 0.7881 | 0.070* | |
C34 | 0.9115 (2) | 0.5512 (3) | 0.7063 (2) | 0.0514 (6) | |
C35 | 1.0190 (3) | 0.4924 (5) | 0.6807 (3) | 0.0818 (11) | |
H351 | 0.9953 | 0.4324 | 0.6167 | 0.123* | |
H352 | 1.0645 | 0.4334 | 0.7400 | 0.123* | |
H353 | 1.0641 | 0.5747 | 0.6695 | 0.123* | |
C36 | 0.8441 (3) | 0.4143 (4) | 0.7229 (3) | 0.0675 (8) | |
H361 | 0.8178 | 0.3591 | 0.6568 | 0.101* | |
H362 | 0.7790 | 0.4454 | 0.7442 | 0.101* | |
H363 | 0.8934 | 0.3524 | 0.7782 | 0.101* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.116 (3) | 0.059 (2) | 0.0604 (18) | 0.0020 (19) | 0.0290 (19) | 0.0113 (16) |
O2 | 0.0808 (15) | 0.0665 (13) | 0.0427 (10) | −0.0010 (11) | 0.0103 (10) | 0.0045 (9) |
C3 | 0.0529 (15) | 0.0495 (15) | 0.0383 (12) | 0.0023 (11) | 0.0194 (11) | −0.0029 (10) |
C4 | 0.0604 (17) | 0.0476 (16) | 0.0457 (14) | −0.0119 (12) | 0.0174 (12) | −0.0003 (11) |
C5 | 0.0471 (14) | 0.0473 (15) | 0.0484 (14) | −0.0121 (11) | 0.0113 (11) | −0.0028 (11) |
C6 | 0.0410 (11) | 0.0371 (13) | 0.0385 (11) | −0.0034 (9) | 0.0167 (9) | −0.0069 (9) |
C7 | 0.0440 (12) | 0.0441 (13) | 0.0463 (12) | −0.0095 (11) | 0.0179 (10) | −0.0083 (11) |
C8 | 0.0443 (13) | 0.0558 (15) | 0.0425 (13) | −0.0048 (11) | 0.0110 (11) | −0.0111 (11) |
C9 | 0.0385 (12) | 0.0344 (12) | 0.0475 (13) | −0.0026 (9) | 0.0164 (10) | −0.0041 (10) |
O10 | 0.0425 (9) | 0.0470 (10) | 0.0548 (10) | 0.0072 (7) | 0.0198 (8) | −0.0058 (8) |
C11 | 0.0416 (12) | 0.0376 (13) | 0.0477 (12) | 0.0022 (10) | 0.0152 (10) | 0.0034 (10) |
C12 | 0.0397 (12) | 0.0366 (13) | 0.0430 (12) | −0.0009 (9) | 0.0154 (10) | 0.0028 (9) |
C13 | 0.0399 (11) | 0.0331 (12) | 0.0414 (11) | 0.0027 (9) | 0.0151 (9) | 0.0026 (9) |
C14 | 0.0437 (13) | 0.0639 (19) | 0.0720 (18) | 0.0044 (13) | 0.0244 (13) | 0.0005 (15) |
C15 | 0.0500 (15) | 0.0387 (13) | 0.0465 (13) | −0.0054 (10) | 0.0172 (11) | 0.0039 (10) |
O16 | 0.0484 (11) | 0.0605 (12) | 0.0622 (12) | −0.0086 (9) | 0.0081 (9) | −0.0052 (10) |
O17 | 0.0558 (11) | 0.0604 (12) | 0.0479 (10) | −0.0131 (9) | 0.0229 (9) | −0.0170 (8) |
C18 | 0.076 (2) | 0.073 (2) | 0.0667 (19) | −0.0268 (17) | 0.0337 (16) | −0.0320 (16) |
C19 | 0.121 (3) | 0.057 (2) | 0.091 (3) | −0.010 (2) | 0.054 (2) | −0.0196 (18) |
C20 | 0.111 (3) | 0.134 (4) | 0.0484 (19) | 0.012 (3) | 0.009 (2) | −0.021 (2) |
C21 | 0.0405 (12) | 0.0352 (12) | 0.0512 (13) | 0.0038 (10) | 0.0202 (10) | 0.0043 (10) |
O22 | 0.0573 (12) | 0.0647 (13) | 0.0955 (16) | 0.0279 (10) | 0.0409 (11) | 0.0424 (12) |
N23 | 0.0345 (9) | 0.0401 (11) | 0.0379 (9) | 0.0033 (7) | 0.0133 (8) | 0.0096 (8) |
C24 | 0.0424 (13) | 0.0421 (13) | 0.0387 (12) | 0.0002 (10) | 0.0154 (10) | 0.0082 (9) |
C25 | 0.0370 (12) | 0.0521 (14) | 0.0413 (12) | −0.0054 (10) | 0.0157 (10) | −0.0005 (11) |
C26 | 0.0338 (11) | 0.0693 (18) | 0.0468 (13) | −0.0052 (11) | 0.0130 (10) | 0.0001 (12) |
S27 | 0.0371 (3) | 0.0800 (5) | 0.0395 (3) | 0.0008 (3) | 0.0105 (2) | 0.0148 (3) |
O28 | 0.0540 (13) | 0.106 (2) | 0.121 (2) | 0.0194 (13) | 0.0294 (13) | 0.0802 (18) |
O29 | 0.0636 (14) | 0.189 (3) | 0.0458 (11) | −0.0204 (17) | 0.0206 (10) | −0.0385 (16) |
C30 | 0.0494 (15) | 0.076 (2) | 0.0438 (14) | 0.0042 (13) | 0.0128 (12) | 0.0144 (13) |
C31 | 0.0527 (15) | 0.091 (2) | 0.0370 (12) | −0.0090 (15) | 0.0150 (11) | −0.0003 (14) |
C32 | 0.073 (2) | 0.096 (3) | 0.0548 (17) | −0.0107 (18) | 0.0314 (16) | 0.0172 (17) |
C33 | 0.0521 (16) | 0.0677 (19) | 0.0582 (16) | −0.0156 (13) | 0.0232 (13) | 0.0073 (14) |
C34 | 0.0477 (14) | 0.0619 (18) | 0.0475 (14) | −0.0026 (12) | 0.0189 (11) | −0.0096 (11) |
C35 | 0.072 (2) | 0.100 (3) | 0.082 (2) | 0.0074 (19) | 0.0358 (19) | −0.024 (2) |
C36 | 0.075 (2) | 0.0550 (19) | 0.074 (2) | −0.0106 (15) | 0.0250 (17) | −0.0213 (15) |
C1—O2 | 1.423 (4) | C18—C19 | 1.494 (5) |
O2—C3 | 1.376 (3) | C18—C20 | 1.524 (6) |
C3—C8 | 1.377 (4) | C21—O22 | 1.211 (3) |
C3—C4 | 1.381 (4) | C21—N23 | 1.388 (3) |
C4—C5 | 1.379 (4) | N23—C24 | 1.480 (3) |
C5—C6 | 1.389 (3) | N23—S27 | 1.6785 (19) |
C6—C7 | 1.387 (3) | C24—C30 | 1.538 (4) |
C6—C9 | 1.504 (3) | C24—C25 | 1.549 (3) |
C7—C8 | 1.378 (4) | C25—C26 | 1.520 (3) |
C9—O10 | 1.467 (3) | C25—C33 | 1.531 (4) |
C9—C13 | 1.563 (3) | C25—C34 | 1.552 (4) |
O10—C11 | 1.354 (3) | C26—S27 | 1.777 (2) |
C11—C12 | 1.340 (3) | S27—O29 | 1.419 (3) |
C11—C14 | 1.482 (3) | S27—O28 | 1.422 (3) |
C12—C15 | 1.454 (3) | C30—C31 | 1.533 (4) |
C12—C13 | 1.509 (3) | C31—C34 | 1.530 (4) |
C13—C21 | 1.526 (3) | C31—C32 | 1.542 (5) |
C15—O16 | 1.210 (3) | C32—C33 | 1.549 (4) |
C15—O17 | 1.347 (3) | C34—C36 | 1.533 (4) |
O17—C18 | 1.469 (3) | C34—C35 | 1.543 (4) |
C3—O2—C1 | 117.4 (2) | N23—C21—C13 | 118.47 (19) |
O2—C3—C8 | 116.0 (2) | C21—N23—C24 | 119.17 (18) |
O2—C3—C4 | 124.0 (2) | C21—N23—S27 | 122.25 (15) |
C8—C3—C4 | 119.9 (2) | C24—N23—S27 | 110.52 (14) |
C5—C4—C3 | 119.3 (3) | N23—C24—C30 | 114.7 (2) |
C4—C5—C6 | 121.8 (2) | N23—C24—C25 | 106.23 (18) |
C7—C6—C5 | 117.6 (2) | C30—C24—C25 | 103.54 (19) |
C7—C6—C9 | 121.7 (2) | C26—C25—C33 | 118.3 (2) |
C5—C6—C9 | 120.6 (2) | C26—C25—C24 | 108.46 (18) |
C8—C7—C6 | 121.1 (2) | C33—C25—C24 | 104.8 (2) |
C3—C8—C7 | 120.2 (2) | C26—C25—C34 | 117.7 (2) |
O10—C9—C6 | 108.14 (18) | C33—C25—C34 | 102.3 (2) |
O10—C9—C13 | 104.76 (17) | C24—C25—C34 | 103.59 (19) |
C6—C9—C13 | 114.56 (19) | C25—C26—S27 | 107.18 (16) |
C11—O10—C9 | 108.61 (17) | O29—S27—O28 | 117.1 (2) |
C12—C11—O10 | 114.2 (2) | O29—S27—N23 | 109.02 (16) |
C12—C11—C14 | 131.8 (2) | O28—S27—N23 | 109.40 (13) |
O10—C11—C14 | 114.0 (2) | O29—S27—C26 | 110.57 (15) |
C11—C12—C15 | 125.4 (2) | O28—S27—C26 | 112.36 (16) |
C11—C12—C13 | 109.3 (2) | N23—S27—C26 | 96.38 (10) |
C15—C12—C13 | 125.3 (2) | C31—C30—C24 | 102.0 (2) |
C12—C13—C21 | 109.84 (19) | C34—C31—C30 | 102.7 (2) |
C12—C13—C9 | 101.73 (18) | C34—C31—C32 | 102.7 (2) |
C21—C13—C9 | 111.65 (19) | C30—C31—C32 | 108.0 (3) |
O16—C15—O17 | 123.6 (2) | C31—C32—C33 | 103.3 (2) |
O16—C15—C12 | 125.4 (2) | C25—C33—C32 | 102.2 (2) |
O17—C15—C12 | 110.9 (2) | C31—C34—C36 | 114.8 (2) |
C15—O17—C18 | 116.6 (2) | C31—C34—C35 | 114.3 (3) |
O17—C18—C19 | 107.1 (3) | C36—C34—C35 | 106.4 (3) |
O17—C18—C20 | 107.4 (3) | C31—C34—C25 | 92.6 (2) |
C19—C18—C20 | 113.3 (3) | C36—C34—C25 | 116.0 (2) |
O22—C21—N23 | 119.2 (2) | C35—C34—C25 | 112.7 (2) |
O22—C21—C13 | 122.3 (2) |
Experimental details
Crystal data | |
Chemical formula | C27H35NO7S |
Mr | 517.62 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 293 |
a, b, c (Å) | 12.1894 (7), 8.9921 (3), 13.0425 (8) |
β (°) | 107.97 (1) |
V (Å3) | 1359.83 (12) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.16 |
Crystal size (mm) | 0.42 × 0.41 × 0.32 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12731, 6413, 5079 |
Rint | 0.082 |
(sin θ/λ)max (Å−1) | 0.674 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.128, 1.02 |
No. of reflections | 6413 |
No. of parameters | 332 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.26 |
Absolute structure | Flack (1983) |
Absolute structure parameter | 0.03 (8) |
Computer programs: DENZO (Otwinowski & Minor, 1997), DENZO, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson, 1976), PLATON (Spek, 1990).
The addition of isopropyl 3-oxobutanoate to compound (1) [(1S,2R)-N-[(E)-4-methoxycinnamoyl]-10,2-camphorsultam] in the presence of Mn(OAc)3, using a previously described method, affords the title molecule, (2), as a major isomer, the reaction being totally regio- and diastereoselective (Garzino et al., 2000). The facial selectivity of the MnIII-mediated addition of β-keto esters to olefins can be controlled by introduction of a chiral auxiliary on the substrate (Curran et al., 1996). This reaction thereby provides an entry to chiral dihydrofurans. The structures of the starting compound (Garzino et al., 2002) and of the dihydrofuran adduct were thus elucidated in order to know their relative configuration and to understand how the diastereoselection is controlled. When using compound (I) as substrate, dihydrofuran (2) was selectively formed.
The absolute configurations of the two stereogenic centres were determined by X-ray analysis. It appears that, when (-)-10,2-camphorsultam was used as the chiral inductor, the (2R,3R)-dihydrofuran (2) was selectively obtained, with a specific rotation of -229.0° in choroform for a concentration c = 0.7 (2R is atom C9 and 3R is atom C13). As it is known that in such radical reactions the transition state resembles the substrate, the explanation of such a facial selectivity can be provided by the crystal structure of the starting compound (1). Indeed it can be seen that, in this compound, the anti s-cis conformation is favoured by dipolar interactions between the cinnamate C═O group and the equatorial S═O group of the sulfonyl moiety. In this conformation, the approach by the lower face is hindered by the axial S═O, thus enabling the facial stereoselectivity to be controlled. It is interesting to notice that the addition of isopropyl 3-oxobutanoate to compound (1) affects considerably the conjugation of the π sytem. The value of the torsion angle C9—C10—C11—O12 changes from 19.8 (2) to 76.40 (3)°.