Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010401947X/fr1504sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010401947X/fr1504Isup2.hkl |
CCDC reference: 254928
Compound (I) was prepared by Jones oxidation of (-)-(1R)-2-endo-3-exo-isoborneolacetic acid, purchased from Aldrich Chemical Co., Milwaukee, Wisconsin, USA. Recrystallization from 1:1 cyclohexane-ethyl ether provided crystals of (I) suitable for X-ray analysis (m.p. 358 K). The positive rotation of the (1R)-enantiomer of (I) has been established (Rupe & Häfliger, 1940).
All H atoms for (I) were found in electron-density difference maps but were placed in calculated positions, with C—H = 0.97 for methylene H, 0.98 for methine H and 0.96 Å for methyl H, and O—H = 0.82 Å for carboxyl H, and allowed to refine as riding models on their respective C and O atoms, with Uiso(H) = 1.5Ueq(O,Cmethyl) and 1.2Ueq(C) for the rest.
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C12H18O3 | F(000) = 456 |
Mr = 210.26 | Dx = 1.210 Mg m−3 |
Monoclinic, P21 | Melting point: 358 K |
Hall symbol: P 2yb | Mo Kα radiation, λ = 0.71073 Å |
a = 6.6423 (10) Å | Cell parameters from 25 reflections |
b = 14.734 (3) Å | θ = 6.0–13.2° |
c = 11.817 (2) Å | µ = 0.09 mm−1 |
β = 93.756 (13)° | T = 296 K |
V = 1154.0 (4) Å3 | Tablet, colorless |
Z = 4 | 0.38 × 0.30 × 0.18 mm |
Siemens P4 diffractometer | 1161 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.077 |
Graphite monochromator | θmax = 25.0°, θmin = 2.2° |
2θ/θ scans | h = −7→7 |
Absorption correction: numerical (SHELXTL; Sheldrick, 1997) | k = −17→17 |
Tmin = 0.972, Tmax = 0.986 | l = −14→14 |
4574 measured reflections | 3 standard reflections every 97 reflections |
2110 independent reflections | intensity decay: variation <2.0% |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 0.99 | w = 1/[σ2(Fo2) + (0.006P)2] where P = (Fo2 + 2Fc2)/3 |
2110 reflections | (Δ/σ)max < 0.001 |
271 parameters | Δρmax = 0.16 e Å−3 |
1 restraint | Δρmin = −0.16 e Å−3 |
C12H18O3 | V = 1154.0 (4) Å3 |
Mr = 210.26 | Z = 4 |
Monoclinic, P21 | Mo Kα radiation |
a = 6.6423 (10) Å | µ = 0.09 mm−1 |
b = 14.734 (3) Å | T = 296 K |
c = 11.817 (2) Å | 0.38 × 0.30 × 0.18 mm |
β = 93.756 (13)° |
Siemens P4 diffractometer | 1161 reflections with I > 2σ(I) |
Absorption correction: numerical (SHELXTL; Sheldrick, 1997) | Rint = 0.077 |
Tmin = 0.972, Tmax = 0.986 | 3 standard reflections every 97 reflections |
4574 measured reflections | intensity decay: variation <2.0% |
2110 independent reflections |
R[F2 > 2σ(F2)] = 0.049 | 1 restraint |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 0.99 | Δρmax = 0.16 e Å−3 |
2110 reflections | Δρmin = −0.16 e Å−3 |
271 parameters |
Experimental. crystal mounted on glass fiber using cyanoacrylate cement |
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 | ||
O1A | 0.9351 (6) | 0.2404 (2) | −0.0072 (3) | 0.0568 (11) | |
O1B | 0.5695 (6) | 0.2151 (2) | 0.4699 (3) | 0.0532 (10) | |
C1B | 0.8954 (8) | 0.0387 (4) | 0.5688 (4) | 0.0476 (14) | |
H1B | 0.9018 | −0.0210 | 0.6053 | 0.057* | |
C1A | 0.5993 (8) | 0.4175 (3) | 0.0558 (4) | 0.0511 (15) | |
H1A | 0.5907 | 0.4801 | 0.0833 | 0.061* | |
O2A | 0.8965 (8) | 0.5708 (3) | −0.1945 (4) | 0.1067 (17) | |
O2B | 0.5550 (6) | −0.1271 (2) | 0.3241 (3) | 0.0745 (13) | |
C2B | 0.6849 (8) | 0.0623 (3) | 0.5135 (4) | 0.0432 (14) | |
H2B | 0.5853 | 0.0483 | 0.5686 | 0.052* | |
C2A | 0.8032 (8) | 0.3932 (3) | 0.0117 (4) | 0.0403 (13) | |
H2A | 0.9078 | 0.4145 | 0.0678 | 0.048* | |
O3A | 0.9693 (7) | 0.5607 (2) | −0.0116 (3) | 0.0721 (13) | |
H3A | 0.9926 | 0.6150 | −0.0186 | 0.108* | |
O3B | 0.5233 (7) | −0.1072 (2) | 0.5075 (3) | 0.0663 (11) | |
H3B | 0.4968 | −0.1616 | 0.5064 | 0.100* | |
C3B | 0.7053 (8) | 0.1667 (3) | 0.5077 (4) | 0.0369 (13) | |
C3A | 0.7987 (8) | 0.2906 (3) | 0.0189 (4) | 0.0409 (13) | |
C4B | 0.9072 (8) | 0.1920 (4) | 0.5562 (5) | 0.0494 (14) | |
C4A | 0.6015 (8) | 0.2641 (3) | 0.0642 (5) | 0.0493 (14) | |
C5B | 1.0477 (9) | 0.1563 (4) | 0.4664 (6) | 0.0724 (19) | |
H5C | 1.1826 | 0.1809 | 0.4797 | 0.087* | |
H5D | 0.9959 | 0.1729 | 0.3906 | 0.087* | |
C5A | 0.4484 (9) | 0.2910 (5) | −0.0338 (5) | 0.074 (2) | |
H5A | 0.4925 | 0.2692 | −0.1056 | 0.089* | |
H5B | 0.3169 | 0.2652 | −0.0223 | 0.089* | |
C6B | 1.0494 (9) | 0.0513 (4) | 0.4811 (6) | 0.0637 (17) | |
H6C | 1.0085 | 0.0207 | 0.4107 | 0.076* | |
H6D | 1.1815 | 0.0295 | 0.5087 | 0.076* | |
C6A | 0.4378 (8) | 0.3929 (5) | −0.0338 (5) | 0.0605 (16) | |
H6A | 0.4667 | 0.4178 | −0.1070 | 0.073* | |
H6B | 0.3065 | 0.4141 | −0.0138 | 0.073* | |
C7B | 0.9361 (8) | 0.1173 (4) | 0.6511 (4) | 0.0538 (14) | |
C7A | 0.5744 (7) | 0.3440 (4) | 0.1493 (4) | 0.0488 (13) | |
C8B | 0.7803 (9) | 0.1285 (4) | 0.7417 (4) | 0.0778 (19) | |
H8D | 0.8016 | 0.0822 | 0.7984 | 0.117* | |
H8E | 0.6465 | 0.1230 | 0.7064 | 0.117* | |
H8F | 0.7959 | 0.1871 | 0.7765 | 0.117* | |
C8A | 0.7396 (8) | 0.3467 (4) | 0.2462 (4) | 0.0663 (16) | |
H8A | 0.7157 | 0.3969 | 0.2954 | 0.099* | |
H8B | 0.8688 | 0.3538 | 0.2154 | 0.099* | |
H8C | 0.7377 | 0.2911 | 0.2885 | 0.099* | |
C9B | 1.1458 (9) | 0.1176 (5) | 0.7142 (6) | 0.091 (2) | |
H9D | 1.1526 | 0.0705 | 0.7703 | 0.136* | |
H9E | 1.1691 | 0.1753 | 0.7504 | 0.136* | |
H9F | 1.2468 | 0.1073 | 0.6611 | 0.136* | |
C9A | 0.3731 (8) | 0.3455 (4) | 0.2003 (5) | 0.0783 (19) | |
H9A | 0.3676 | 0.3961 | 0.2512 | 0.117* | |
H9B | 0.3552 | 0.2901 | 0.2414 | 0.117* | |
H9C | 0.2678 | 0.3511 | 0.1411 | 0.117* | |
C10A | 0.5894 (10) | 0.1686 (4) | 0.1092 (6) | 0.090 (2) | |
H10A | 0.6083 | 0.1263 | 0.0491 | 0.134* | |
H10B | 0.4595 | 0.1591 | 0.1383 | 0.134* | |
H10C | 0.6928 | 0.1598 | 0.1688 | 0.134* | |
C10B | 0.9351 (9) | 0.2898 (4) | 0.5882 (6) | 0.085 (2) | |
H10D | 0.9121 | 0.3271 | 0.5220 | 0.127* | |
H10E | 1.0701 | 0.2991 | 0.6202 | 0.127* | |
H10F | 0.8408 | 0.3059 | 0.6431 | 0.127* | |
C11B | 0.6116 (8) | 0.0204 (3) | 0.4011 (4) | 0.0483 (15) | |
H11C | 0.7148 | 0.0293 | 0.3478 | 0.058* | |
H11D | 0.4925 | 0.0532 | 0.3721 | 0.058* | |
C11A | 0.8593 (8) | 0.4269 (3) | −0.1043 (4) | 0.0503 (14) | |
H11A | 0.9746 | 0.3924 | −0.1267 | 0.060* | |
H11B | 0.7477 | 0.4144 | −0.1592 | 0.060* | |
C12B | 0.5604 (8) | −0.0800 (4) | 0.4039 (4) | 0.0461 (13) | |
C12A | 0.9097 (9) | 0.5266 (4) | −0.1100 (5) | 0.0570 (16) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1A | 0.059 (3) | 0.036 (2) | 0.078 (3) | 0.0076 (19) | 0.020 (2) | 0.0014 (19) |
O1B | 0.054 (2) | 0.042 (2) | 0.063 (2) | 0.0071 (19) | −0.001 (2) | −0.0022 (18) |
C1B | 0.063 (4) | 0.032 (3) | 0.048 (3) | 0.002 (3) | 0.007 (3) | 0.006 (3) |
C1A | 0.065 (4) | 0.038 (3) | 0.051 (3) | 0.016 (3) | 0.008 (3) | 0.000 (3) |
O2A | 0.191 (5) | 0.074 (3) | 0.056 (2) | −0.019 (3) | 0.018 (3) | 0.017 (2) |
O2B | 0.122 (4) | 0.050 (3) | 0.052 (2) | −0.016 (2) | 0.008 (2) | −0.018 (2) |
C2B | 0.057 (4) | 0.033 (3) | 0.040 (3) | 0.000 (3) | 0.009 (3) | −0.001 (2) |
C2A | 0.045 (3) | 0.032 (3) | 0.044 (3) | −0.001 (3) | 0.003 (3) | −0.002 (2) |
O3A | 0.116 (4) | 0.036 (2) | 0.064 (2) | −0.021 (3) | 0.009 (2) | 0.005 (2) |
O3B | 0.112 (3) | 0.036 (2) | 0.053 (2) | −0.030 (2) | 0.018 (2) | −0.0053 (19) |
C3B | 0.036 (3) | 0.032 (3) | 0.043 (3) | 0.010 (3) | 0.004 (3) | 0.001 (2) |
C3A | 0.046 (4) | 0.030 (3) | 0.047 (3) | −0.008 (3) | 0.004 (3) | −0.007 (2) |
C4B | 0.035 (3) | 0.038 (3) | 0.074 (4) | −0.003 (3) | 0.003 (3) | −0.004 (3) |
C4A | 0.038 (3) | 0.034 (3) | 0.076 (4) | −0.007 (2) | 0.006 (3) | −0.013 (3) |
C5B | 0.054 (4) | 0.074 (5) | 0.091 (5) | −0.006 (4) | 0.014 (4) | 0.010 (4) |
C5A | 0.052 (4) | 0.097 (6) | 0.073 (4) | −0.020 (4) | 0.010 (4) | −0.020 (4) |
C6B | 0.055 (4) | 0.056 (4) | 0.080 (4) | 0.017 (3) | 0.009 (3) | −0.001 (3) |
C6A | 0.041 (4) | 0.079 (5) | 0.061 (4) | 0.018 (3) | −0.003 (3) | −0.003 (3) |
C7B | 0.054 (3) | 0.046 (3) | 0.060 (3) | −0.003 (3) | −0.004 (3) | −0.005 (3) |
C7A | 0.047 (3) | 0.049 (3) | 0.051 (3) | −0.001 (3) | 0.007 (3) | −0.005 (3) |
C8B | 0.111 (5) | 0.074 (4) | 0.049 (3) | −0.009 (4) | 0.011 (3) | −0.006 (3) |
C8A | 0.078 (4) | 0.073 (4) | 0.048 (3) | −0.002 (4) | 0.004 (3) | 0.016 (3) |
C9B | 0.083 (5) | 0.080 (5) | 0.106 (5) | 0.012 (4) | −0.024 (4) | 0.002 (4) |
C9A | 0.071 (4) | 0.088 (5) | 0.079 (4) | 0.016 (4) | 0.029 (3) | 0.005 (4) |
C10A | 0.102 (6) | 0.044 (4) | 0.128 (5) | −0.025 (4) | 0.053 (5) | −0.009 (4) |
C10B | 0.069 (5) | 0.049 (4) | 0.134 (6) | −0.018 (4) | −0.012 (4) | −0.016 (4) |
C11B | 0.070 (4) | 0.032 (3) | 0.043 (3) | 0.002 (3) | 0.006 (3) | 0.005 (2) |
C11A | 0.060 (4) | 0.044 (3) | 0.047 (3) | −0.002 (3) | 0.005 (3) | 0.000 (3) |
C12B | 0.050 (3) | 0.042 (3) | 0.046 (3) | −0.001 (3) | 0.002 (3) | −0.008 (3) |
C12A | 0.076 (4) | 0.056 (4) | 0.040 (3) | −0.001 (3) | 0.007 (3) | 0.005 (3) |
O1A—C3A | 1.224 (6) | C5A—H5A | 0.9700 |
O1B—C3B | 1.213 (5) | C5A—H5B | 0.9700 |
C1B—C6B | 1.514 (7) | C6B—H6C | 0.9700 |
C1B—C7B | 1.526 (7) | C6B—H6D | 0.9700 |
C1B—C2B | 1.544 (7) | C6A—H6A | 0.9700 |
C1B—H1B | 0.9800 | C6A—H6B | 0.9700 |
C1A—C6A | 1.501 (7) | C7B—C9B | 1.536 (7) |
C1A—C2A | 1.526 (7) | C7B—C8B | 1.546 (7) |
C1A—C7A | 1.564 (7) | C7A—C9A | 1.503 (6) |
C1A—H1A | 0.9800 | C7A—C8A | 1.533 (7) |
O2A—C12A | 1.190 (6) | C8B—H8D | 0.9600 |
O2B—C12B | 1.171 (5) | C8B—H8E | 0.9600 |
C2B—C11B | 1.516 (6) | C8B—H8F | 0.9600 |
C2B—C3B | 1.546 (6) | C8A—H8A | 0.9600 |
C2B—H2B | 0.9800 | C8A—H8B | 0.9600 |
C2A—C3A | 1.514 (6) | C8A—H8C | 0.9600 |
C2A—C11A | 1.528 (6) | C9B—H9D | 0.9600 |
C2A—H2A | 0.9800 | C9B—H9E | 0.9600 |
O3A—C12A | 1.304 (6) | C9B—H9F | 0.9600 |
O3A—H3A | 0.8200 | C9A—H9A | 0.9600 |
O3B—C12B | 1.326 (6) | C9A—H9B | 0.9600 |
O3B—H3B | 0.8200 | C9A—H9C | 0.9600 |
C3B—C4B | 1.472 (7) | C10A—H10A | 0.9600 |
C3A—C4A | 1.499 (7) | C10A—H10B | 0.9600 |
C4B—C10B | 1.498 (8) | C10A—H10C | 0.9600 |
C4B—C5B | 1.550 (8) | C10B—H10D | 0.9600 |
C4B—C7B | 1.574 (8) | C10B—H10E | 0.9600 |
C4A—C10A | 1.508 (7) | C10B—H10F | 0.9600 |
C4A—C5A | 1.542 (8) | C11B—C12B | 1.519 (7) |
C4A—C7A | 1.567 (7) | C11B—H11C | 0.9700 |
C5B—C6B | 1.557 (9) | C11B—H11D | 0.9700 |
C5B—H5C | 0.9700 | C11A—C12A | 1.510 (8) |
C5B—H5D | 0.9700 | C11A—H11A | 0.9700 |
C5A—C6A | 1.504 (9) | C11A—H11B | 0.9700 |
C6B—C1B—C7B | 104.1 (5) | H6A—C6A—H6B | 109.2 |
C6B—C1B—C2B | 108.5 (4) | C1B—C7B—C9B | 115.4 (5) |
C7B—C1B—C2B | 102.5 (4) | C1B—C7B—C8B | 115.1 (5) |
C6B—C1B—H1B | 113.6 | C9B—C7B—C8B | 106.9 (4) |
C7B—C1B—H1B | 113.6 | C1B—C7B—C4B | 93.9 (3) |
C2B—C1B—H1B | 113.6 | C9B—C7B—C4B | 114.1 (5) |
C6A—C1A—C2A | 108.2 (4) | C8B—C7B—C4B | 111.3 (4) |
C6A—C1A—C7A | 103.2 (4) | C9A—C7A—C8A | 108.2 (4) |
C2A—C1A—C7A | 102.4 (4) | C9A—C7A—C1A | 114.3 (4) |
C6A—C1A—H1A | 114.0 | C8A—C7A—C1A | 113.9 (4) |
C2A—C1A—H1A | 114.0 | C9A—C7A—C4A | 114.3 (4) |
C7A—C1A—H1A | 114.0 | C8A—C7A—C4A | 113.1 (4) |
C11B—C2B—C1B | 120.6 (4) | C1A—C7A—C4A | 92.5 (3) |
C11B—C2B—C3B | 113.0 (4) | C7B—C8B—H8D | 109.5 |
C1B—C2B—C3B | 99.4 (4) | C7B—C8B—H8E | 109.5 |
C11B—C2B—H2B | 107.7 | H8D—C8B—H8E | 109.5 |
C1B—C2B—H2B | 107.7 | C7B—C8B—H8F | 109.5 |
C3B—C2B—H2B | 107.7 | H8D—C8B—H8F | 109.5 |
C3A—C2A—C1A | 101.2 (5) | H8E—C8B—H8F | 109.5 |
C3A—C2A—C11A | 112.4 (4) | C7A—C8A—H8A | 109.5 |
C1A—C2A—C11A | 120.3 (4) | C7A—C8A—H8B | 109.5 |
C3A—C2A—H2A | 107.4 | H8A—C8A—H8B | 109.5 |
C1A—C2A—H2A | 107.4 | C7A—C8A—H8C | 109.5 |
C11A—C2A—H2A | 107.4 | H8A—C8A—H8C | 109.5 |
C12A—O3A—H3A | 109.5 | H8B—C8A—H8C | 109.5 |
C12B—O3B—H3B | 109.5 | C7B—C9B—H9D | 109.5 |
O1B—C3B—C4B | 129.1 (5) | C7B—C9B—H9E | 109.5 |
O1B—C3B—C2B | 122.5 (5) | H9D—C9B—H9E | 109.5 |
C4B—C3B—C2B | 108.4 (4) | C7B—C9B—H9F | 109.5 |
O1A—C3A—C4A | 127.7 (5) | H9D—C9B—H9F | 109.5 |
O1A—C3A—C2A | 124.8 (5) | H9E—C9B—H9F | 109.5 |
C4A—C3A—C2A | 107.5 (5) | C7A—C9A—H9A | 109.5 |
C3B—C4B—C10B | 115.9 (5) | C7A—C9A—H9B | 109.5 |
C3B—C4B—C5B | 102.8 (4) | H9A—C9A—H9B | 109.5 |
C10B—C4B—C5B | 115.5 (5) | C7A—C9A—H9C | 109.5 |
C3B—C4B—C7B | 99.5 (4) | H9A—C9A—H9C | 109.5 |
C10B—C4B—C7B | 119.0 (5) | H9B—C9A—H9C | 109.5 |
C5B—C4B—C7B | 101.5 (4) | C4A—C10A—H10A | 109.5 |
C3A—C4A—C10A | 115.9 (5) | C4A—C10A—H10B | 109.5 |
C3A—C4A—C5A | 102.3 (4) | H10A—C10A—H10B | 109.5 |
C10A—C4A—C5A | 117.2 (5) | C4A—C10A—H10C | 109.5 |
C3A—C4A—C7A | 100.0 (4) | H10A—C10A—H10C | 109.5 |
C10A—C4A—C7A | 117.6 (5) | H10B—C10A—H10C | 109.5 |
C5A—C4A—C7A | 101.0 (4) | C4B—C10B—H10D | 109.5 |
C4B—C5B—C6B | 105.2 (5) | C4B—C10B—H10E | 109.5 |
C4B—C5B—H5C | 110.7 | H10D—C10B—H10E | 109.5 |
C6B—C5B—H5C | 110.7 | C4B—C10B—H10F | 109.5 |
C4B—C5B—H5D | 110.7 | H10D—C10B—H10F | 109.5 |
C6B—C5B—H5D | 110.7 | H10E—C10B—H10F | 109.5 |
H5C—C5B—H5D | 108.8 | C2B—C11B—C12B | 115.9 (4) |
C6A—C5A—C4A | 106.5 (5) | C2B—C11B—H11C | 108.3 |
C6A—C5A—H5A | 110.4 | C12B—C11B—H11C | 108.3 |
C4A—C5A—H5A | 110.4 | C2B—C11B—H11D | 108.3 |
C6A—C5A—H5B | 110.4 | C12B—C11B—H11D | 108.3 |
C4A—C5A—H5B | 110.4 | H11C—C11B—H11D | 107.4 |
H5A—C5A—H5B | 108.6 | C12A—C11A—C2A | 115.1 (4) |
C1B—C6B—C5B | 101.4 (5) | C12A—C11A—H11A | 108.5 |
C1B—C6B—H6C | 111.5 | C2A—C11A—H11A | 108.5 |
C5B—C6B—H6C | 111.5 | C12A—C11A—H11B | 108.5 |
C1B—C6B—H6D | 111.5 | C2A—C11A—H11B | 108.5 |
C5B—C6B—H6D | 111.5 | H11A—C11A—H11B | 107.5 |
H6C—C6B—H6D | 109.3 | O2B—C12B—O3B | 124.5 (5) |
C1A—C6A—C5A | 102.1 (5) | O2B—C12B—C11B | 123.7 (5) |
C1A—C6A—H6A | 111.3 | O3B—C12B—C11B | 111.7 (5) |
C5A—C6A—H6A | 111.3 | O2A—C12A—O3A | 122.6 (6) |
C1A—C6A—H6B | 111.3 | O2A—C12A—C11A | 124.4 (5) |
C5A—C6A—H6B | 111.3 | O3A—C12A—C11A | 113.0 (5) |
C6B—C1B—C2B—C11B | 50.6 (6) | C4A—C5A—C6A—C1A | 5.4 (6) |
C7B—C1B—C2B—C11B | 160.3 (5) | C6B—C1B—C7B—C9B | −62.5 (6) |
C6B—C1B—C2B—C3B | −73.3 (5) | C2B—C1B—C7B—C9B | −175.4 (5) |
C7B—C1B—C2B—C3B | 36.4 (4) | C6B—C1B—C7B—C8B | 172.2 (4) |
C6A—C1A—C2A—C3A | −72.6 (5) | C2B—C1B—C7B—C8B | 59.3 (5) |
C7A—C1A—C2A—C3A | 35.9 (5) | C6B—C1B—C7B—C4B | 56.5 (5) |
C6A—C1A—C2A—C11A | 51.8 (6) | C2B—C1B—C7B—C4B | −56.4 (4) |
C7A—C1A—C2A—C11A | 160.4 (4) | C3B—C4B—C7B—C1B | 54.5 (4) |
C11B—C2B—C3B—O1B | 51.7 (7) | C10B—C4B—C7B—C1B | −178.7 (5) |
C1B—C2B—C3B—O1B | −179.2 (4) | C5B—C4B—C7B—C1B | −50.7 (5) |
C11B—C2B—C3B—C4B | −129.3 (5) | C3B—C4B—C7B—C9B | 174.6 (5) |
C1B—C2B—C3B—C4B | −0.2 (5) | C10B—C4B—C7B—C9B | −58.6 (7) |
C1A—C2A—C3A—O1A | −179.2 (4) | C5B—C4B—C7B—C9B | 69.3 (5) |
C11A—C2A—C3A—O1A | 51.2 (7) | C3B—C4B—C7B—C8B | −64.3 (5) |
C1A—C2A—C3A—C4A | 0.1 (5) | C10B—C4B—C7B—C8B | 62.5 (7) |
C11A—C2A—C3A—C4A | −129.5 (4) | C5B—C4B—C7B—C8B | −169.6 (4) |
O1B—C3B—C4B—C10B | 15.6 (8) | C6A—C1A—C7A—C9A | −61.7 (5) |
C2B—C3B—C4B—C10B | −163.3 (5) | C2A—C1A—C7A—C9A | −174.0 (4) |
O1B—C3B—C4B—C5B | −111.3 (6) | C6A—C1A—C7A—C8A | 173.2 (4) |
C2B—C3B—C4B—C5B | 69.8 (5) | C2A—C1A—C7A—C8A | 60.9 (5) |
O1B—C3B—C4B—C7B | 144.5 (5) | C6A—C1A—C7A—C4A | 56.5 (5) |
C2B—C3B—C4B—C7B | −34.4 (5) | C2A—C1A—C7A—C4A | −55.9 (4) |
O1A—C3A—C4A—C10A | 16.1 (8) | C3A—C4A—C7A—C9A | 172.4 (4) |
C2A—C3A—C4A—C10A | −163.2 (5) | C10A—C4A—C7A—C9A | −61.3 (6) |
O1A—C3A—C4A—C5A | −112.7 (6) | C5A—C4A—C7A—C9A | 67.5 (5) |
C2A—C3A—C4A—C5A | 68.1 (5) | C3A—C4A—C7A—C8A | −63.2 (5) |
O1A—C3A—C4A—C7A | 143.6 (5) | C10A—C4A—C7A—C8A | 63.1 (6) |
C2A—C3A—C4A—C7A | −35.7 (5) | C5A—C4A—C7A—C8A | −168.0 (4) |
C3B—C4B—C5B—C6B | −73.5 (6) | C3A—C4A—C7A—C1A | 54.2 (4) |
C10B—C4B—C5B—C6B | 159.3 (6) | C10A—C4A—C7A—C1A | −179.5 (5) |
C7B—C4B—C5B—C6B | 29.1 (6) | C5A—C4A—C7A—C1A | −50.6 (4) |
C3A—C4A—C5A—C6A | −72.7 (6) | C1B—C2B—C11B—C12B | 70.9 (6) |
C10A—C4A—C5A—C6A | 159.4 (5) | C3B—C2B—C11B—C12B | −171.9 (4) |
C7A—C4A—C5A—C6A | 30.3 (6) | C3A—C2A—C11A—C12A | −167.6 (4) |
C7B—C1B—C6B—C5B | −39.7 (6) | C1A—C2A—C11A—C12A | 73.4 (7) |
C2B—C1B—C6B—C5B | 69.0 (6) | C2B—C11B—C12B—O2B | −158.6 (5) |
C4B—C5B—C6B—C1B | 5.3 (6) | C2B—C11B—C12B—O3B | 21.3 (7) |
C2A—C1A—C6A—C5A | 68.3 (6) | C2A—C11A—C12A—O2A | −156.0 (6) |
C7A—C1A—C6A—C5A | −39.7 (6) | C2A—C11A—C12A—O3A | 23.7 (7) |
Experimental details
Crystal data | |
Chemical formula | C12H18O3 |
Mr | 210.26 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 296 |
a, b, c (Å) | 6.6423 (10), 14.734 (3), 11.817 (2) |
β (°) | 93.756 (13) |
V (Å3) | 1154.0 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.38 × 0.30 × 0.18 |
Data collection | |
Diffractometer | Siemens P4 diffractometer |
Absorption correction | Numerical (SHELXTL; Sheldrick, 1997) |
Tmin, Tmax | 0.972, 0.986 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4574, 2110, 1161 |
Rint | 0.077 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.096, 0.99 |
No. of reflections | 2110 |
No. of parameters | 271 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.16, −0.16 |
Computer programs: XSCANS (Siemens, 1996), XSCANS, SHELXTL (Sheldrick, 1997), SHELXTL.
O2A—C12A | 1.190 (6) | O3A—C12A | 1.304 (6) |
O2B—C12B | 1.171 (5) | O3B—C12B | 1.326 (6) |
O2B—C12B—C11B | 123.7 (5) | O2A—C12A—C11A | 124.4 (5) |
O3B—C12B—C11B | 111.7 (5) | O3A—C12A—C11A | 113.0 (5) |
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Simple crystalline carboxylic acids typically aggregate as hydrogen-bonding dimers, a pattern that often changes when other hydrogen-bonding functionalities are present. In our X-ray study of the five known hydrogen-bonding motifs for keto acids, we have found that carboxyl pairing is inhibited whenever centrosymmetry is thwarted (Lalancette & Thompson, 2003) or molecular flexibility is severely curtailed (Lalancette Brunskill & Thompson, 1999; Barcon et al., 2002). Hence, our attention has often centered on single enantiomers and on cyclic systems. The title compound, (I), incorporates both these restraints, and the observed hydrogen-bonding involves carboxyl-to-ketone chains (catemers). \sch
The category of γ-keto acids to which (I) belongs is rich in hydrogen-bonding types, embracing dimers, internal hydrogen bonds, and catemers of the screw, translational and glide types. In the lower homolog of (I), camphorcarboxylic acid (Lalancette et al., 1991), both the enantiomeric and racemic forms exhibit the catemeric hydrogen-bonding arrangement. The relationship of camphorcarboxylic acid to (I) is of interest, because we have found racemic cases in which homologation by a single CH2 unit suffices to shift the hydrogen-bonding pattern from catemer to dimer (Lalancette Brunskill & Thompson, 1999; Barcon et al., 2002). This is believed to reflect the expanded repertoire of centrosymmetric dimerization patterns of low energy that results from greater molecular flexibility. However, in nonracemates, this flexibility is typically overridden by the unavailability of centrosymmetric modes (Coté et al., 1997; Lalancette Thompson & Brunskill, 1999).
Fig. 1 presents a view of the asymmetric unit of (I) with the atom-numbering scheme. Compound (I) is skeletally rigid except for rotation about the C2—C11 and C11—C12 bonds, and the two molecules differ almost solely in slight rotations about these two bonds. Both molecules adopt a C2—C11-staggered conformation, with the carboxyl aimed away from the ketone. In molecule (IA), the C3A—C2A—C11A—C12A torsion angle is −167.6 (4)°, while in (IB) this angle is −171.9 (4)°. The carboxyl group is rotated so that the O3—C12—C11—C2 torsion angles are 23.7 (7) and 21.3 (7)° in (IA) and (IB), respectively. The resulting dihedral angle between the carboxyl and ketone planes (O2—C12—O3 versus C2—C3—C4—O1) is 80.1 (2)° in the case of (IA) and 75.9 (2)° for (IB).
The partial averaging of C—O bond lengths and C—C—O angles by disorder often found in acids is seen only in the dimeric hydrogen-bonding mode, the geometry of which allows transposition of the two carboxyl O atoms. As in other catemers, no significant averaging is observed for the carboxyl groups of (IA) and (IB). The bond lengths for (IA) are 1.190 (6) and 1.304 (6) Å, with angles of 124.4 (5) and 113.0 (5)°, while for (IB) these lengths are 1.171 (5) and 1.326 (6) Å, with angles of 123.7 (5) and 111.7 (5)°. Our own survey of 56 non-dimeric keto acid structures gives average values of 1.200 (10) and 1.32 (2) Å and 124.5 (14) and 112.7 (17)° for these lengths and angles, in accord with typical values of 1.21 and 1.31 Å and 123 and 112°, cited for highly ordered dimeric carboxyls (Borthwick, 1980). The three methyl groups present are fully ordered in both (IA) and (IB) and staggered relative to the substituents at their points of attachment.
Fig. 2 shows a packing diagram for the cell of (I). Each molecule in the asymmetric unit aggregates with its own type to generate the two single-strand hydrogen-bonding catemers illustrated by the inclusion of extracellular molecules. Both of these independent counterdirectional chains follow screw axes parallel to b.
We characterize the geometry of hydrogen bonding to carbonyls using a combination of the H···O═C angle and the H···O═C—C torsion angle. These describe the approach of the H atom to the O in terms of its deviation from, respectively, C═O axiality (ideal 120°) and planarity with the carbonyl (ideal 0°). For (IA), these angles are H···O═C 136.0 and H···O═C—C −14.9°. For the (IB) catemers, the corresponding values are 133.2 and −23.6°, respectively.
Three close C—H···O═C contacts exist for the ketone and carboxyl functions. The ketone in (IA) has a contact to atom H5B in a translationally related neighbor (2.58 Å), and the ketone in (IB) has a corresponding translational contact to atom H5C of 2.63 Å. The carboxyl carbonyl (C═O2B) has a 2.64 Å contact to atom H6A in a screw-related neighbor. These distances all lie within the 2.7 Å range we normally employ for non-bonded H···O packing interactions (Steiner, 1997). Using compiled data for a large number of C—H···O contacts, Steiner & Desiraju (1998) find significant statistical directionality even as far out as 3.0 Å, and conclude that these are legitimately viewed as `weak hydrogen bonds', with a greater contribution to packing forces than simple van der Waals attractions.
The solid-state (KBr) IR spectrum of (I) has broad C═O absorption with maxima at 1736 and 1711 cm−1, essentially identical to those for camphorcarboxylic acid (Lalancette et al., 1991). These peaks are consistent with hydrogen-bonding shifts due, respectively, to its removal from COOH and its addition to a strained ketone. In CHCl3, where dimers predominate, the absorptions appear, presumably reversed, at 1738 and 1712 cm−1.