Acta Cryst. (2008). E64, o607 [ doi:10.1107/S1600536808004583 ]
![[epsilon]](/logos/entities/epsiv_rmgif.gif)
-caprolactoneThe chiral title compound, C7H12O2, a lactone derivative, features a seven-membered ring that adopts a chair conformation. The crystal structure is stabilized by weak C-H
O interactions occurring in the (100) plane. The absolute configuration was assigned on the basis of the enantioselective synthesis.
Details about the synthesis of (S)-6-methyl-ε-caprolactone have been given in a previous paper (van As et al., 2007).
In the absence of significant anomalous scattering effects, XXX Friedel pairs were merged prior to the refinement. The H atoms were found in difference Fourier maps and subsequently placed at calculated positions with C–H = 0.99–1.00 Å, and with Uiso(H) = 1.2 or 1.5 times Ueq(carrier C).
Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS86 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003) and Mercury (Macrae et al., 2006).
![[Figure 1]](./tk2248fig1thm.gif)
| Fig. 1. Molecular structure of (I) showing atom labelling and displacement ellipsoids at the 50% probability level. |
![[Figure 2]](./tk2248fig2thm.gif)
| Fig. 2. The packing of one layer found in the crystal structure of (I) viewed down the a* direction. Molecules are connected by short C–H···O contacts in the (1 0 0) plane. Only one set of short contacts (dashed lines) is shown for clarity. The symmetry codes are: (i) 2 - x, -1/2 + y, -z; (iii) 2 - x, 1/2 + y, -z; (iv) x, y, z - 1. |
| C7H12O2 | F000 = 140 |
| Mr = 128.17 | Dx = 1.174 Mg m−3 |
| Monoclinic, P21 | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: P 2yb | Cell parameters from 7835 reflections |
| a = 6.757 (2) Å | θ = 1.0–27.5º |
| b = 7.577 (2) Å | µ = 0.08 mm−1 |
| c = 7.586 (2) Å | T = 150 (2) K |
| β = 110.949 (13)º | Prism, colourless |
| V = 362.71 (17) Å3 | 0.35 × 0.15 × 0.10 mm |
| Z = 2 |
| Nonius KappaCCD diffractometer | 862 reflections with I > 2σ(I) |
| Radiation source: rotating anode | Rint = 0.041 |
| Monochromator: graphite | θmax = 27.5º |
| T = 150(2) K | θmin = 3.5º |
| φ and ω scans | h = −8→8 |
| Absorption correction: none | k = −9→9 |
| 10010 measured reflections | l = −9→9 |
| 889 independent reflections |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
| wR(F2) = 0.072 | w = 1/[σ2(Fo2) + (0.0431P)2 + 0.0282P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.10 | (Δ/σ)max < 0.001 |
| 889 reflections | Δρmax = 0.12 e Å−3 |
| 83 parameters | Δρmin = −0.16 e Å−3 |
| 1 restraint | Extinction correction: none |
| Primary atom site location: structure-invariant direct methods | Absolute structure: known chirality of atom C6(S) |
| C7H12O2 | V = 362.71 (17) Å3 |
| Mr = 128.17 | Z = 2 |
| Monoclinic, P21 | Mo Kα |
| a = 6.757 (2) Å | µ = 0.08 mm−1 |
| b = 7.577 (2) Å | T = 150 (2) K |
| c = 7.586 (2) Å | 0.35 × 0.15 × 0.10 mm |
| β = 110.949 (13)º |
| Nonius KappaCCD diffractometer | 889 independent reflections |
| Absorption correction: none | 862 reflections with I > 2σ(I) |
| 10010 measured reflections | Rint = 0.041 |
| R[F2 > 2σ(F2)] = 0.027 | H-atom parameters constrained |
| wR(F2) = 0.072 | Δρmax = 0.12 e Å−3 |
| S = 1.10 | Δρmin = −0.16 e Å−3 |
| 889 reflections | Absolute structure: known chirality of atom C6(S) |
| 83 parameters | Flack parameter: ? |
| 1 restraint | Rogers parameter: ? |
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 > 2σ(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 | ||
| O1 | 1.03545 (16) | 0.06828 (15) | −0.16671 (13) | 0.0355 (3) | |
| O2 | 1.11573 (13) | 0.04935 (14) | 0.13758 (12) | 0.0288 (2) | |
| C1 | 0.9754 (2) | 0.03155 (18) | −0.03896 (16) | 0.0258 (3) | |
| C2 | 0.7534 (2) | −0.0285 (2) | −0.07029 (18) | 0.0301 (3) | |
| H2A | 0.7594 | −0.1422 | −0.0042 | 0.036* | |
| H2B | 0.6778 | −0.0491 | −0.2069 | 0.036* | |
| C3 | 0.6274 (2) | 0.1054 (2) | 0.0003 (2) | 0.0356 (3) | |
| H3A | 0.6603 | 0.2261 | −0.0311 | 0.043* | |
| H3B | 0.4740 | 0.0849 | −0.0669 | 0.043* | |
| C4 | 0.6759 (2) | 0.0938 (2) | 0.2120 (2) | 0.0365 (3) | |
| H4A | 0.6389 | −0.0260 | 0.2421 | 0.044* | |
| H4B | 0.5841 | 0.1787 | 0.2461 | 0.044* | |
| C5 | 0.9066 (2) | 0.1315 (2) | 0.33415 (18) | 0.0303 (3) | |
| H5A | 0.9423 | 0.2528 | 0.3071 | 0.036* | |
| H5B | 0.9205 | 0.1274 | 0.4685 | 0.036* | |
| C6 | 1.06592 (19) | 0.00512 (19) | 0.30521 (16) | 0.0267 (3) | |
| H6 | 1.0098 | −0.1181 | 0.2938 | 0.032* | |
| C7 | 1.2785 (2) | 0.0148 (3) | 0.46522 (19) | 0.0403 (4) | |
| H7A | 1.3333 | 0.1356 | 0.4759 | 0.060* | |
| H7B | 1.3783 | −0.0660 | 0.4396 | 0.060* | |
| H7C | 1.2615 | −0.0190 | 0.5837 | 0.060* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O1 | 0.0442 (5) | 0.0406 (6) | 0.0260 (5) | 0.0001 (5) | 0.0177 (4) | 0.0018 (4) |
| O2 | 0.0248 (4) | 0.0400 (6) | 0.0219 (4) | −0.0028 (4) | 0.0087 (3) | 0.0022 (4) |
| C1 | 0.0305 (6) | 0.0245 (6) | 0.0221 (6) | 0.0029 (5) | 0.0093 (5) | −0.0007 (5) |
| C2 | 0.0272 (6) | 0.0341 (7) | 0.0255 (6) | −0.0021 (5) | 0.0050 (5) | −0.0041 (6) |
| C3 | 0.0242 (6) | 0.0431 (9) | 0.0365 (7) | 0.0058 (6) | 0.0074 (5) | 0.0002 (7) |
| C4 | 0.0298 (6) | 0.0451 (9) | 0.0382 (7) | 0.0031 (6) | 0.0166 (5) | −0.0030 (7) |
| C5 | 0.0360 (7) | 0.0322 (7) | 0.0254 (6) | −0.0015 (6) | 0.0143 (5) | −0.0026 (5) |
| C6 | 0.0265 (6) | 0.0330 (7) | 0.0202 (6) | −0.0027 (5) | 0.0079 (5) | 0.0028 (5) |
| C7 | 0.0311 (6) | 0.0598 (11) | 0.0252 (6) | −0.0040 (7) | 0.0043 (5) | 0.0070 (7) |
| O1—C1 | 1.2095 (16) | C4—H4A | 0.9900 |
| O2—C1 | 1.3428 (15) | C4—H4B | 0.9900 |
| O2—C6 | 1.4659 (14) | C5—C6 | 1.5140 (19) |
| C1—C2 | 1.5028 (18) | C5—H5A | 0.9900 |
| C2—C3 | 1.539 (2) | C5—H5B | 0.9900 |
| C2—H2A | 0.9900 | C6—C7 | 1.5152 (18) |
| C2—H2B | 0.9900 | C6—H6 | 1.0000 |
| C3—C4 | 1.523 (2) | C7—H7A | 0.9800 |
| C3—H3A | 0.9900 | C7—H7B | 0.9800 |
| C3—H3B | 0.9900 | C7—H7C | 0.9800 |
| C4—C5 | 1.5288 (19) | ||
| C1—O2—C6 | 122.88 (10) | C5—C4—H4B | 108.6 |
| O1—C1—O2 | 117.15 (12) | H4A—C4—H4B | 107.6 |
| O1—C1—C2 | 123.02 (11) | C6—C5—C4 | 114.69 (12) |
| O2—C1—C2 | 119.82 (11) | C6—C5—H5A | 108.6 |
| C1—C2—C3 | 112.99 (12) | C4—C5—H5A | 108.6 |
| C1—C2—H2A | 109.0 | C6—C5—H5B | 108.6 |
| C3—C2—H2A | 109.0 | C4—C5—H5B | 108.6 |
| C1—C2—H2B | 109.0 | H5A—C5—H5B | 107.6 |
| C3—C2—H2B | 109.0 | O2—C6—C5 | 112.13 (11) |
| H2A—C2—H2B | 107.8 | O2—C6—C7 | 103.76 (10) |
| C4—C3—C2 | 113.05 (12) | C5—C6—C7 | 111.89 (12) |
| C4—C3—H3A | 109.0 | O2—C6—H6 | 109.6 |
| C2—C3—H3A | 109.0 | C5—C6—H6 | 109.6 |
| C4—C3—H3B | 109.0 | C7—C6—H6 | 109.6 |
| C2—C3—H3B | 109.0 | C6—C7—H7A | 109.5 |
| H3A—C3—H3B | 107.8 | C6—C7—H7B | 109.5 |
| C3—C4—C5 | 114.64 (11) | H7A—C7—H7B | 109.5 |
| C3—C4—H4A | 108.6 | C6—C7—H7C | 109.5 |
| C5—C4—H4A | 108.6 | H7A—C7—H7C | 109.5 |
| C3—C4—H4B | 108.6 | H7B—C7—H7C | 109.5 |
| C6—O2—C1—O1 | −178.35 (12) | C3—C4—C5—C6 | −61.49 (19) |
| C6—O2—C1—C2 | 2.78 (18) | C1—O2—C6—C5 | −68.78 (16) |
| O1—C1—C2—C3 | −112.90 (16) | C1—O2—C6—C7 | 170.29 (13) |
| O2—C1—C2—C3 | 65.90 (16) | C4—C5—C6—O2 | 80.45 (14) |
| C1—C2—C3—C4 | −81.25 (16) | C4—C5—C6—C7 | −163.43 (12) |
| C2—C3—C4—C5 | 61.39 (19) |
| C—H···O | C—H | H···O | C···O | C—H···A |
| C2—H2A···O1i | 0.99 | 2.67 | 3.573 (2) | 152 |
| C5—H5A···O1ii | 0.99 | 2.64 | 3.616 (2) | 166 |
| C5—H5B···O1ii | 0.99 | 2.63 | 3.601 (2) | 168 |
| C6—H6···O1i | 1.00 | 2.54 | 3.466 (2) | 154 |
| Symmetry codes: (i) -x+2, y-1/2, -z; (ii) x, y, z+1. |
We thank Ir. (Dr?) Bart A. C. van As, Dr Anja R. A. Palmans and Professor E. W. Meijer for providing crystals of the title compound. This work was supported by the Council for Chemical Sciences of the Netherlands Organization for Scientific Research (CW-NWO).
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The enantiomers (R)- and (S)-6-methyl-ε-caprolactone (6-MeCL) have been recently used as monomer units for chiral oligomerization and chiral polymerization reactions (van As et al., 2005; van Buijtenen et al., 2006). A new two-step enantioselective synthesis of (R)- and (S)-6-MeCL from a racemic mixture of 6-MeCL has been described recently (van As et al., 2007). The present paper describes the crystal structure of (S)-6-MeCL, (I).
The structure of (I) (Fig. 1) was solved in the non-centrosymmetric space group P21 with Z' = 1. The stereochemistry at the chiral center, C6, was assigned S based on the enantioselective synthesis of (S)-6-MeCL, which was reported to yield an enantiomeric excess greater than 99% (van As et al., 2007).
The seven-membered ring (O2/C1—C6) adopts a chair conformation with puckering parameters: Q2 = 0.453 (2) Å, φ2 = 130.6 (2)°, Q3 = 0.653 (2) Å, φ3 = 102.6 (2)° and with a total puckering amplitude Q = 0.795 (2)Å (Cremer & Pople, 1975).
The crystal structure (I) is stabilized by weak C–H···O interactions (Table 1) with the four shortest contacts involving the O1 atom. These short contacts occur between molecules in the (1 0 0) plane, Fig. 2.