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The molecule of the title compound, C16H21NO4, is chiral and has three asymmetric centres. The absolute configuration was not determined via diffraction measurements on the crystal, but was established from the known absolute configuration of the starting material. In the crystal structure, the molecules assemble through intermolecular hydrogen bonds into a macrostructure with helical channels.
Supporting information
CCDC reference: 605689
The title compound was synthesized following an analogous procedure to that described by Evans, Downey et al. (2002) for related compounds. To a round-bottomed flask in a glove box was added MgBr2·OEt2 (36 mg, 0.5 equivalents). The flask was fitted with a septum cap and removed to an ambient atmosphere, where it was charged with N-acylated phenyliminooxazolidine (0.28 mmol, 72 mg, 1 equivalent), EtOAc (3 ml), benzaldehyde (0.30 mmol, 31 µl, 1.1 equivalents), Et3N (0.55 mmol, 77 µl, 2 equivalents) and trimethylsilyl chloride (0.41 mmol, 53 µl, 1.5 equivalents). The reaction mixture was stirred for 26 h and then filtered directly through a plug of silica gel (5.5 cm × 4.0 cm) and eluted with Et2O. The eluent was concentrated and dissolved in tetrahydrofuran (50 ml) and treated with 1.0 N HCl (10 ml). After stirring for 1 h, the mixture was diluted with Et2O (100 ml) and water (100 ml). The organic layer was extracted with saturated NaHCO3 (50 ml), dried, filtered and concentrated. Flash chromatography (EtOAc–hexane = 2:8) afforded pure compound (I) in 58% yield. Single crystals suitable for an X-ray diffraction study were obtained by slow evaporation of a toluene solution over a period of one week. Spectroscopic analysis: 1H NMR (CDCl3, δ, p.p.m.): 7.42–7.29 (m, 5H), 4.75 (bt, 1H, J = 6.3 Hz), 4.46–4.17 (m, 4H), 3.17 (bd, 1H, J = 6.6 Hz), 2.30–2.23 (m, 1H), 1.10 (d, 1H, J = 6.9 Hz), 0.87 (d, 1H, J = 7.1 Hz), 0.70 (d, 1H, J = 6.9 Hz); 13C NMR (CDCl3, δ, p.p.m): 176.7, 154.2, 142.2, 128.5, 128.0, 126.5, 77.4, 63.2, 58.8, 43.9, 28.3, 17.9, 14.8, 14.3; MS (EI) m/z 291 (M+).
In the absence of significant anomalous scattering, Friedel opposites were merged. All H atoms were positioned geometrically and allowed to ride on their respective carrier atoms, with O1—H = 0.83 Å and Uiso(H) = 1.5Ueq(O1), and C—H = 0.94–0.99 Å and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(C).
Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
(4
S)-3-[(2
R,3S)-3-Hydroxy-2-methyl-3-phenylpropionyl]-4- isopropyloxazolidin-2-one
top
Crystal data top
C16H21NO4 | F(000) = 312 |
Mr = 291.34 | Dx = 1.220 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 634 reflections |
a = 11.6191 (10) Å | θ = 1.8–28.2° |
b = 6.1749 (5) Å | µ = 0.09 mm−1 |
c = 12.0431 (10) Å | T = 243 K |
β = 113.394 (2)° | Block, colourless |
V = 793.02 (11) Å3 | 0.1 × 0.1 × 0.1 mm |
Z = 2 | |
Data collection top
Bruker SMART 1000 area-detector CCD diffractometer | 908 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.041 |
Graphite monochromator | θmax = 28.2°, θmin = 1.8° |
ϕ and ω scans | h = −15→10 |
5052 measured reflections | k = −7→7 |
1976 independent reflections | l = −12→15 |
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: inferred from neighbouring sites |
wR(F2) = 0.061 | H-atom parameters constrained |
S = 0.82 | w = 1/[σ2(Fo2) + (0.0121P)2] where P = (Fo2 + 2Fc2)/3 |
1976 reflections | (Δ/σ)max < 0.001 |
194 parameters | Δρmax = 0.10 e Å−3 |
1 restraint | Δρmin = −0.11 e Å−3 |
Crystal data top
C16H21NO4 | V = 793.02 (11) Å3 |
Mr = 291.34 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 11.6191 (10) Å | µ = 0.09 mm−1 |
b = 6.1749 (5) Å | T = 243 K |
c = 12.0431 (10) Å | 0.1 × 0.1 × 0.1 mm |
β = 113.394 (2)° | |
Data collection top
Bruker SMART 1000 area-detector CCD diffractometer | 908 reflections with I > 2σ(I) |
5052 measured reflections | Rint = 0.041 |
1976 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 1 restraint |
wR(F2) = 0.061 | H-atom parameters constrained |
S = 0.82 | Δρmax = 0.10 e Å−3 |
1976 reflections | Δρmin = −0.11 e Å−3 |
194 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 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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.3867 (2) | 0.5784 (3) | 0.01675 (19) | 0.0666 (7) | |
H1 | 0.3771 | 0.6181 | −0.0522 | 0.100* | |
O2 | 0.59887 (19) | 0.2834 (4) | 0.19135 (19) | 0.0580 (7) | |
O3 | 0.5394 (2) | 0.5608 (4) | 0.5043 (2) | 0.0650 (7) | |
O4 | 0.3574 (2) | 0.5237 (4) | 0.3468 (2) | 0.0702 (8) | |
N1 | 0.5480 (2) | 0.4363 (4) | 0.3336 (2) | 0.0457 (7) | |
C1 | 0.2101 (3) | 0.3282 (6) | −0.0618 (3) | 0.0517 (9) | |
C2 | 0.1648 (3) | 0.1345 (6) | −0.1206 (3) | 0.0649 (11) | |
H2 | 0.2218 | 0.0247 | −0.1180 | 0.078* | |
C3 | 0.0374 (4) | 0.0980 (7) | −0.1833 (3) | 0.0880 (15) | |
H3 | 0.0082 | −0.0352 | −0.2221 | 0.106* | |
C4 | −0.0449 (4) | 0.2597 (10) | −0.1877 (4) | 0.0995 (18) | |
H4 | −0.1315 | 0.2381 | −0.2307 | 0.119* | |
C5 | −0.0016 (4) | 0.4551 (9) | −0.1293 (4) | 0.0979 (15) | |
H5 | −0.0588 | 0.5646 | −0.1317 | 0.118* | |
C6 | 0.1252 (3) | 0.4886 (6) | −0.0680 (3) | 0.0721 (11) | |
H6 | 0.1542 | 0.6223 | −0.0299 | 0.086* | |
C7 | 0.3484 (3) | 0.3568 (5) | 0.0130 (3) | 0.0496 (9) | |
H7 | 0.3976 | 0.2642 | −0.0192 | 0.059* | |
C8 | 0.3773 (3) | 0.2981 (5) | 0.1433 (3) | 0.0483 (9) | |
H8 | 0.3247 | 0.3877 | 0.1729 | 0.058* | |
C9 | 0.3540 (3) | 0.0572 (6) | 0.1603 (3) | 0.0721 (11) | |
H9A | 0.4057 | −0.0316 | 0.1319 | 0.108* | |
H9B | 0.2663 | 0.0231 | 0.1144 | 0.108* | |
H9C | 0.3755 | 0.0283 | 0.2454 | 0.108* | |
C10 | 0.5143 (3) | 0.3415 (5) | 0.2209 (3) | 0.0501 (9) | |
C11 | 0.4686 (4) | 0.5044 (5) | 0.3881 (3) | 0.0537 (10) | |
C12 | 0.6692 (3) | 0.5064 (6) | 0.5352 (3) | 0.0700 (11) | |
H12A | 0.6933 | 0.3806 | 0.5892 | 0.084* | |
H12B | 0.7235 | 0.6284 | 0.5760 | 0.084* | |
C13 | 0.6814 (3) | 0.4554 (5) | 0.4176 (3) | 0.0540 (10) | |
H13 | 0.7226 | 0.3127 | 0.4246 | 0.065* | |
C14 | 0.7530 (3) | 0.6226 (6) | 0.3781 (3) | 0.0656 (11) | |
H14 | 0.7502 | 0.5765 | 0.2984 | 0.079* | |
C15 | 0.8895 (3) | 0.6271 (6) | 0.4650 (4) | 0.1254 (19) | |
H15A | 0.9388 | 0.6974 | 0.4266 | 0.188* | |
H15B | 0.9193 | 0.4801 | 0.4869 | 0.188* | |
H15C | 0.8978 | 0.7067 | 0.5373 | 0.188* | |
C16 | 0.6968 (4) | 0.8484 (6) | 0.3626 (4) | 0.1024 (16) | |
H16A | 0.6120 | 0.8455 | 0.3011 | 0.154* | |
H16B | 0.7473 | 0.9474 | 0.3381 | 0.154* | |
H16C | 0.6954 | 0.8966 | 0.4387 | 0.154* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0718 (16) | 0.0637 (17) | 0.0633 (16) | −0.0116 (15) | 0.0256 (14) | 0.0064 (14) |
O2 | 0.0506 (15) | 0.0655 (17) | 0.0608 (16) | −0.0009 (14) | 0.0250 (12) | −0.0111 (13) |
O3 | 0.0760 (18) | 0.0653 (16) | 0.0523 (15) | −0.0091 (15) | 0.0240 (13) | −0.0128 (14) |
O4 | 0.0597 (16) | 0.087 (2) | 0.0664 (16) | 0.0104 (17) | 0.0270 (13) | −0.0065 (15) |
N1 | 0.0475 (17) | 0.0444 (18) | 0.0429 (17) | 0.0014 (14) | 0.0158 (14) | −0.0008 (14) |
C1 | 0.045 (2) | 0.066 (3) | 0.044 (2) | −0.003 (2) | 0.0167 (17) | 0.005 (2) |
C2 | 0.057 (3) | 0.081 (3) | 0.054 (2) | −0.003 (2) | 0.0191 (19) | −0.007 (2) |
C3 | 0.071 (3) | 0.099 (4) | 0.072 (3) | −0.023 (3) | 0.005 (2) | 0.006 (3) |
C4 | 0.053 (3) | 0.131 (5) | 0.087 (4) | −0.023 (3) | −0.001 (3) | 0.034 (3) |
C5 | 0.062 (3) | 0.111 (4) | 0.119 (4) | 0.023 (3) | 0.035 (3) | 0.037 (3) |
C6 | 0.056 (3) | 0.067 (3) | 0.091 (3) | 0.002 (2) | 0.027 (2) | 0.007 (2) |
C7 | 0.050 (2) | 0.046 (2) | 0.055 (2) | −0.003 (2) | 0.0234 (18) | −0.0035 (19) |
C8 | 0.043 (2) | 0.058 (2) | 0.046 (2) | 0.002 (2) | 0.0189 (16) | −0.0029 (19) |
C9 | 0.070 (2) | 0.075 (3) | 0.061 (2) | −0.022 (2) | 0.0162 (18) | 0.014 (2) |
C10 | 0.054 (2) | 0.046 (2) | 0.050 (2) | −0.005 (2) | 0.0201 (19) | −0.0001 (19) |
C11 | 0.067 (3) | 0.042 (2) | 0.052 (2) | −0.002 (2) | 0.024 (2) | −0.0035 (19) |
C12 | 0.067 (3) | 0.078 (3) | 0.054 (2) | −0.016 (2) | 0.011 (2) | 0.000 (2) |
C13 | 0.051 (2) | 0.041 (2) | 0.057 (2) | 0.0006 (18) | 0.0083 (18) | −0.0027 (19) |
C14 | 0.060 (2) | 0.068 (3) | 0.068 (3) | −0.018 (2) | 0.025 (2) | −0.014 (2) |
C15 | 0.051 (3) | 0.108 (4) | 0.188 (5) | −0.020 (3) | 0.016 (3) | −0.016 (4) |
C16 | 0.110 (4) | 0.059 (3) | 0.141 (4) | −0.011 (3) | 0.053 (3) | 0.029 (3) |
Geometric parameters (Å, º) top
O1—C7 | 1.434 (3) | C7—H7 | 0.9900 |
O1—H1 | 0.8300 | C8—C10 | 1.517 (4) |
O2—C10 | 1.224 (3) | C8—C9 | 1.540 (4) |
O3—C11 | 1.357 (3) | C8—H8 | 0.9900 |
O3—C12 | 1.443 (3) | C9—H9A | 0.9700 |
O4—C11 | 1.192 (3) | C9—H9B | 0.9700 |
N1—C10 | 1.384 (4) | C9—H9C | 0.9700 |
N1—C11 | 1.392 (4) | C12—C13 | 1.512 (4) |
N1—C13 | 1.482 (4) | C12—H12A | 0.9800 |
C1—C6 | 1.379 (4) | C12—H12B | 0.9800 |
C1—C2 | 1.383 (4) | C13—C14 | 1.516 (4) |
C1—C7 | 1.508 (4) | C13—H13 | 0.9900 |
C2—C3 | 1.387 (4) | C14—C15 | 1.514 (4) |
C2—H2 | 0.9400 | C14—C16 | 1.519 (4) |
C3—C4 | 1.369 (5) | C14—H14 | 0.9900 |
C3—H3 | 0.9400 | C15—H15A | 0.9700 |
C4—C5 | 1.387 (6) | C15—H15B | 0.9700 |
C4—H4 | 0.9400 | C15—H15C | 0.9700 |
C5—C6 | 1.376 (5) | C16—H16A | 0.9700 |
C5—H5 | 0.9400 | C16—H16B | 0.9700 |
C6—H6 | 0.9400 | C16—H16C | 0.9700 |
C7—C8 | 1.512 (4) | | |
| | | |
C7—O1—H1 | 109.5 | H9A—C9—H9C | 109.5 |
C11—O3—C12 | 110.4 (3) | H9B—C9—H9C | 109.5 |
C10—N1—C11 | 127.4 (3) | O2—C10—N1 | 117.5 (3) |
C10—N1—C13 | 121.0 (3) | O2—C10—C8 | 122.4 (3) |
C11—N1—C13 | 111.3 (3) | N1—C10—C8 | 119.9 (3) |
C6—C1—C2 | 118.3 (3) | O4—C11—O3 | 121.1 (3) |
C6—C1—C7 | 121.2 (3) | O4—C11—N1 | 130.2 (3) |
C2—C1—C7 | 120.4 (3) | O3—C11—N1 | 108.7 (3) |
C1—C2—C3 | 121.8 (4) | O3—C12—C13 | 106.5 (2) |
C1—C2—H2 | 119.1 | O3—C12—H12A | 110.4 |
C3—C2—H2 | 119.1 | C13—C12—H12A | 110.4 |
C4—C3—C2 | 118.7 (4) | O3—C12—H12B | 110.4 |
C4—C3—H3 | 120.7 | C13—C12—H12B | 110.4 |
C2—C3—H3 | 120.7 | H12A—C12—H12B | 108.6 |
C3—C4—C5 | 120.5 (4) | N1—C13—C12 | 101.2 (3) |
C3—C4—H4 | 119.7 | N1—C13—C14 | 113.4 (3) |
C5—C4—H4 | 119.7 | C12—C13—C14 | 114.8 (3) |
C6—C5—C4 | 119.9 (5) | N1—C13—H13 | 109.1 |
C6—C5—H5 | 120.1 | C12—C13—H13 | 109.1 |
C4—C5—H5 | 120.1 | C14—C13—H13 | 109.1 |
C5—C6—C1 | 120.8 (4) | C15—C14—C13 | 110.5 (3) |
C5—C6—H6 | 119.6 | C15—C14—C16 | 110.4 (3) |
C1—C6—H6 | 119.6 | C13—C14—C16 | 113.6 (3) |
O1—C7—C1 | 112.0 (3) | C15—C14—H14 | 107.3 |
O1—C7—C8 | 104.9 (3) | C13—C14—H14 | 107.3 |
C1—C7—C8 | 109.7 (3) | C16—C14—H14 | 107.3 |
O1—C7—H7 | 110.1 | C14—C15—H15A | 109.5 |
C1—C7—H7 | 110.1 | C14—C15—H15B | 109.5 |
C8—C7—H7 | 110.1 | H15A—C15—H15B | 109.5 |
C7—C8—C10 | 110.1 (3) | C14—C15—H15C | 109.5 |
C7—C8—C9 | 113.1 (3) | H15A—C15—H15C | 109.5 |
C10—C8—C9 | 106.6 (3) | H15B—C15—H15C | 109.5 |
C7—C8—H8 | 109.0 | C14—C16—H16A | 109.5 |
C10—C8—H8 | 109.0 | C14—C16—H16B | 109.5 |
C9—C8—H8 | 109.0 | H16A—C16—H16B | 109.5 |
C8—C9—H9A | 109.5 | C14—C16—H16C | 109.5 |
C8—C9—H9B | 109.5 | H16A—C16—H16C | 109.5 |
H9A—C9—H9B | 109.5 | H16B—C16—H16C | 109.5 |
C8—C9—H9C | 109.5 | | |
| | | |
C6—C1—C2—C3 | −0.9 (5) | C9—C8—C10—O2 | 76.2 (4) |
C7—C1—C2—C3 | 175.6 (3) | C7—C8—C10—N1 | 137.9 (3) |
C1—C2—C3—C4 | 0.7 (6) | C9—C8—C10—N1 | −99.1 (3) |
C2—C3—C4—C5 | −0.7 (7) | C12—O3—C11—O4 | 175.5 (3) |
C3—C4—C5—C6 | 1.0 (7) | C12—O3—C11—N1 | −6.9 (4) |
C4—C5—C6—C1 | −1.3 (6) | C10—N1—C11—O4 | −10.9 (6) |
C2—C1—C6—C5 | 1.2 (5) | C13—N1—C11—O4 | 175.2 (4) |
C7—C1—C6—C5 | −175.3 (3) | C10—N1—C11—O3 | 171.7 (3) |
C6—C1—C7—O1 | −32.2 (4) | C13—N1—C11—O3 | −2.1 (4) |
C2—C1—C7—O1 | 151.4 (3) | C11—O3—C12—C13 | 13.0 (4) |
C6—C1—C7—C8 | 83.8 (4) | C10—N1—C13—C12 | −164.8 (3) |
C2—C1—C7—C8 | −92.6 (4) | C11—N1—C13—C12 | 9.5 (4) |
O1—C7—C8—C10 | −55.6 (3) | C10—N1—C13—C14 | 71.8 (4) |
C1—C7—C8—C10 | −176.0 (3) | C11—N1—C13—C14 | −113.9 (3) |
O1—C7—C8—C9 | −174.6 (3) | O3—C12—C13—N1 | −13.0 (3) |
C1—C7—C8—C9 | 65.0 (4) | O3—C12—C13—C14 | 109.4 (3) |
C11—N1—C10—O2 | −176.6 (3) | N1—C13—C14—C15 | −177.7 (3) |
C13—N1—C10—O2 | −3.3 (4) | C12—C13—C14—C15 | 66.7 (4) |
C11—N1—C10—C8 | −1.1 (5) | N1—C13—C14—C16 | 57.5 (4) |
C13—N1—C10—C8 | 172.3 (3) | C12—C13—C14—C16 | −58.1 (4) |
C7—C8—C10—O2 | −46.8 (4) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O2i | 0.83 | 2.07 | 2.871 (3) | 161 |
C12—H12A···O4ii | 0.98 | 2.48 | 3.369 (4) | 150 |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) −x+1, y−1/2, −z+1. |
Experimental details
Crystal data |
Chemical formula | C16H21NO4 |
Mr | 291.34 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 243 |
a, b, c (Å) | 11.6191 (10), 6.1749 (5), 12.0431 (10) |
β (°) | 113.394 (2) |
V (Å3) | 793.02 (11) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.1 × 0.1 × 0.1 |
|
Data collection |
Diffractometer | Bruker SMART 1000 area-detector CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5052, 1976, 908 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.666 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.061, 0.82 |
No. of reflections | 1976 |
No. of parameters | 194 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.10, −0.11 |
Selected geometric parameters (Å, º) topO1—C7 | 1.434 (3) | N1—C11 | 1.392 (4) |
O2—C10 | 1.224 (3) | N1—C13 | 1.482 (4) |
O3—C11 | 1.357 (3) | C1—C6 | 1.379 (4) |
O3—C12 | 1.443 (3) | C1—C2 | 1.383 (4) |
O4—C11 | 1.192 (3) | C1—C7 | 1.508 (4) |
N1—C10 | 1.384 (4) | C12—C13 | 1.512 (4) |
| | | |
C11—O3—C12 | 110.4 (3) | N1—C10—C8 | 119.9 (3) |
C11—N1—C13 | 111.3 (3) | O4—C11—O3 | 121.1 (3) |
O1—C7—C1 | 112.0 (3) | O4—C11—N1 | 130.2 (3) |
O1—C7—C8 | 104.9 (3) | O3—C11—N1 | 108.7 (3) |
C1—C7—C8 | 109.7 (3) | O3—C12—C13 | 106.5 (2) |
O2—C10—N1 | 117.5 (3) | N1—C13—C12 | 101.2 (3) |
O2—C10—C8 | 122.4 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O2i | 0.83 | 2.07 | 2.871 (3) | 161 |
C12—H12A···O4ii | 0.98 | 2.48 | 3.369 (4) | 150 |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) −x+1, y−1/2, −z+1. |
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Chiral auxiliary-based aldol reactions have been the focus of much interest as the strategy of choice for accessing single isomers of β-hydroxy acid derivatives as chiral building blocks for bioactive compounds (Evans et al., 1981; Ager et al., 1996, 1997; Arya et al., 2000; Evans, Downey et al., 2002; Evans, Tedrow et al., 2002). We recently reported that the use of a new N-acyl phenyliminooxazolidine auxiliary resulted in high diastereoselectivity in alkylation reactions (Lee et al., 2002). During our ongoing studies of chiral auxiliary-based asymmetric reactions, the unexpected title compound, (I), was formed in an aldol reaction and its structure is reported here.
Compound (I) has three chiral C atoms and is one of eight possible stereoisomers. Crystallographically, the absolute configuration has not been established by anomalous dispersion effects, but the R and S configurations of the chiral centres could be assigned by reference to an unchanging asymmetric centre in the reaction procedure. Atoms C7, C8 and C13 have S, R and S configurations, respectively (Fig. 1).
In the crystal structure, molecules of (I) are assembled by two intermolecular hydrogen-bonding interactions, viz. O1—H1···O2i and C12—H12a···O4ii, with O1···O2i = 2.871 (3) Å and C12···O4ii = 3.369 (4) Å [symmetry codes: (i) 1 − x, 1/2 + y, −z; (ii) 1 − x, −1/2 + y, 1 − z]. Atom O1 of the alcohol group and atom C12 in the oxazolidinone ring act as hydrogen-bond donors, and atoms O2 and O4 of the ketone groups act as acceptors (Table 2). The molecules are extended via the hydrogen bonds into a macrostructure, with a left-handed helical chain (O1—H1···O2i; Fig. 2) and a right-handed helical chain (C12—H12A···O4ii; Fig. 3) along the b axis. The cavity of the channel in Fig. 2 has a minimum diameter of 2.816 Å. The molecules stack in layers along the b axis, and the distance between the layers is 6.175 Å. The side view of the hydrogen-bonded left-handed helical chain structure is shown in Fig. 4. The helices are packed in a hexagonal-based array.
Examination of the structure with PLATON (Spek, 2003) reveals a short ring–ring interaction (<6 Å) for oxazolidinone rings. The centroid–centroid distance between Cg1 (the centroid of the five-membered ring O3–C12) and Cg1ii [symmetry code: (ii) 1 − x, −1/2 + y, 1 − z] is 4.222 Å, and the dihedral angle between the ring planes is 35.9°. For phenyl rings, the shortest distance between Cg2 (the centroid of the phenyl ring C1–C6) and Cg2iii [symmetry code: (iii) −x, −1/2 + y, −z] is 5.175 Å, and the dihedral angle is 42.2°.