organic compounds
(1S*,2S*,4S*)-3,3-Difluoro-2,4-dihydroxy-5,5-dimethylcyclooct-5(Z)-en-1-yl N,N-diethylcarbamate
aDepartment of Chemistry, University of Leicester, Leicester LE1 7RH, England, bGlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow CM19 5AW, England, and cChroma Therapeutics Ltd, 93 Milton Park, Abingdon, Oxon OX14 4RY, England
*Correspondence e-mail: jmp29@leicester.ac.uk
The structure of the title compound, C15H25F2NO4, is reported and reveals a pseudorotational relationship between the ring conformation of this compound and that of an isomeric by-product reported in the following paper.
Comment
Conformational equilibria in eight-membered carbocycles occur via two main processes, pseudorotation and ring inversion. The latter exchanges substituent groups between equatorial and axial environments in a pseudo-enantiomeric relationship. Ring inversion is usually the more energetically demanding process; barriers to inversion exchange of 7.3–8.5 kcal mol−1 have been reported, with smaller barriers (ca 5 kcal mol−1) (Servis & Noe, 1973) for the pseudorotation. [For early attempts to apply variable-temperature NMR to these phenomena, see Anderson et al. (1969) and St Jacques et al. (1966).] Recent work from our group has attempted to define these processes for a trio of difluorinated cyclooctenyl systems (Fawcett, Griffith et al., 2005). We were interested in observing a pseudorotational relationship between the ring conformations in the pair of reduction products (1) and (2), obtained upon treatment of a precursor ketone with sodium borohydride.
Product (1) (the major product) arises from the opposite sense of hydride attack, with the N,N-diethylcarbamoyl group retaining its original location (Fig. 1). Product (2), reported in the following paper (Fawcett, Percy et al., 2005), arises from reagent attack on the ring face which bears the hydroxyl group, followed by migration of the N,N-diethylcarbamoyl group on to the newly formed hydroxyl group (Balnaves et al., 1999). A comparison of the two molecules is shown in Fig. 2. O—H⋯O hydrogen bonding links molecules of (1) into chains along the b axis (Table 1).
Experimental
The precursor ketone was prepared as described in the literature (Fawcett, Griffith et al., 2005). Sodium borohydride (1.8 mmol, 70 mg) was added in five portions to a cold (273 K) solution of the ketone (1.8 mmol, 0.59 g) in ethanol (10 ml). After completion of the addition, the reaction mixture was allowed to warm to room temperature, stirred for 2 h at this temperature and poured over a mixture of ice and water (25 ml). HCl (10 ml of a 1 N solution) was added cautiously and the mixture was extracted with diethyl ether (3 × 25 ml). The combined organic extracts were dried (MgSO4), filtered and concentrated under reduced pressure to leave a white solid (0.51 g). Purification by (40% ethyl acetate in light petroleum) afforded the desired diol (1) as a white solid (0.43 g, 72%). RF (40% ethyl acetate in light petroleum) 0.29; m.p. 388–389 K (found: C 56.17, H 7.71, N 4.29%; C15H25F2NO4 requires: C 56.06, H 7.84, N, 4.36%); νmax(KBr)/cm−1 3460 (s br, O—H), 3356 (s br, O—H), 2977 (m, =C—H), 2877 (m, C—H), 1671 (s, C=O); 1H NMR (250 MHz, CDCl3): δ 5.83 (1H, dd, J = 18.5, 9.0 Hz, H-5), 5.53 (1H, t, J = 9.0, 9.0 Hz, H-4), 4.84 (1H, ddd, 3JHF = 21.3, 8.0, 4.1 Hz, H-3), 4.48 (1H, d, J = 5.7 Hz, H-8), 4.18–4.04 (1H, m, H-1), 3.42–3.10 [5H, m, —OH and —N(CH2CH3)2], 2.45 (1H, dd, Jgem = 13.8, J = 8.5 Hz, H-6a), 2.17 (1H, br s, —OH), 1.77 (1H, dd, Jgem = 13.8 Hz, J = 8.3 Hz, H-6b), 1.18–0.93 [12H, m, —N(CH2CH3)2 and 2 × —CH3]; 13C NMR (63 MHz, CDCl3): δ 157.4, 131.4, 131.3 (d, 3JCF = 6.6 Hz), 122.8 (dd, 1JCF = 253.1, 246.9 Hz), 87.4 (d, 3JCF = 9.2 Hz), 70.8 (dd, 2JCF = 23.9, 19.8 Hz), 68.4 (dd, 2JCF = 23.9, 20.9 Hz), 42.8, 42.0, 39.8, 34.9, 30.4, 24.3, 14.5, 13.4; 19F NMR (235 MHz, CDCl3): δ −118.5 (1F, dddd, Jgem = 241.5, 3JHF = 21.2, 10.6, 4JFH = 6.6 Hz), −122.1 (1F, dd, Jgem = 241.5, 3JFH = 16.6 Hz); [HRMS (FAB, [M+H]+) Found: 322.18293, calculated for C15H26F2NO4: 322.18299]; m/z (FAB): 322 (100%, [M+H]+). An analytical sample was recrystallized by vapour diffusion (ethyl acetate/light petroleum) to afford colourless needles.
Crystal data
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Data collection
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Refinement
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H atoms were positioned geometrically, with C—H = 0.95–1.00 Å and O—H = 0.84 Å, and treated as riding, with Uiso(H) = 1.2 or 1.5 (methyl and OH) times Ueq of the parent atom.
Data collection: SMART (Bruker, 1997); cell SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2000); software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536805024839/cf6442sup1.cif
contains datablocks 1, global. DOI:Structure factors: contains datablock 1. DOI: 10.1107/S1600536805024839/cf64421sup2.hkl
The precursor ketone was prepared as described in the literature (Fawcett, Griffith et al., 2005). Sodium borohydride (1.8 mmol, 70 mg) was added in five portions to a cold (273 K) solution of the ketone (1.8 mmol, 0.59 g) in ethanol (10 ml). After completion of the addition, the reaction mixture was allowed to warm to room temperature, stirred for 2 h at this temperature and poured over a mixture of ice and water (25 ml). HCl (10 ml of a 1 N solution) was added cautiously and the mixture was extracted with diethyl ether (3 × 25 ml). The combined organic extracts were dried (MgSO4), filtered and concentrated under reduced pressure to leave a white solid (0.51 g). Purification by νmax(KBr)/cm−1 3460 (s br, O—H), 3356 (s br, O—H), 2977 (m, ═C—H), 2877 (m, C—H), 1671 (s, C═O); 1H NMR (250 MHz, CDCl3): δ 5.83 (1H, dd, J = 18.5, 9.0 Hz, H-5), 5.53 (1H, t, J = 9.0, 9.0 Hz, H-4), 4.84 (1H, ddd, 3JHF = 21.3, 8.0, 4.1 Hz, H-3), 4.48 (1H, d, J = 5.7 Hz, H-8), 4.18–4.04 (1H, m, H-1), 3.42–3.10 [5H, m, –OH and –N(CH2CH3)2], 2.45 (1H, dd, Jgem = 13.8, J = 8.5 Hz, H-6a), 2.17 (1H, br s, –OH), 1.77 (1H, dd, Jgem = 13.8 Hz, J = 8.3 Hz, H-6 b), 1.18–0.93 [12H, m, –N(CH2CH3)2 and 2 × –CH3]; 13C NMR (63 MHz, CDCl3): δ 157.4, 131.4, 131.3 (d, 3JCF = 6.6 Hz), 122.8 (dd, 1JCF = 253.1, 246.9 Hz), 87.4 (d, 3JCF = 9.2 Hz), 70.8 (dd, 2JCF = 23.9, 19.8 Hz), 68.4 (dd, 2JCF = 23.9, 20.9 Hz), 42.8, 42.0, 39.8, 34.9, 30.4, 24.3, 14.5, 13.4; 15F NMR (235 MHz, CDCl3): δ −118.5 (1 F, dddd, Jgem = 241.5, 3JHF = 21.2, 10.6, 4JFH = 6.6 Hz), −122.1 (1 F, dd, Jgem = 241.5, 3JFH = 16.6 Hz); [HRMS (FAB, [M+H]+) Found: 322.18293, calculated for C15H26F2NO4: 322.18299]; m/z (FAB): 322 (100%, [M+H]+). An analytical sample was recrystallized by vapour diffusion (ethyl acetate/light petroleum) to afford colourless needles.
(40% ethyl acetate in light petroleum) afforded the desired diol (1) as a white solid (0.43 g, 72%). RF (40% ethyl acetate in light petroleum) 0.29; m.p. 388–389 K (found: C 56.17, H 7.71, N 4.29%; C15H25F2NO4 requires: C 56.06, H 7.84, N, 4.36%);H atoms were positioned geometrically, with C—H = 0.95–1.00 Å and O—H = 0.84 Å, and treated as riding, with Uiso(H) = 1.2 or 1.5 (methyl and OH) times Ueq of the parent atom.
Data collection: SMART (Bruker, 1997); cell
SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2000); software used to prepare material for publication: SHELXTL.C15H25F2NO4 | F(000) = 344 |
Mr = 321.36 | Dx = 1.342 Mg m−3 |
Monoclinic, Pn | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P -2yac | Cell parameters from 2104 reflections |
a = 7.9651 (14) Å | θ = 2.6–24.7° |
b = 6.4632 (12) Å | µ = 0.11 mm−1 |
c = 15.445 (3) Å | T = 150 K |
β = 90.136 (3)° | Block, colourless |
V = 795.1 (2) Å3 | 0.24 × 0.18 × 0.12 mm |
Z = 2 |
Bruker APEX CCD area-detector diffractometer | 1332 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.041 |
Graphite monochromator | θmax = 25.0°, θmin = 2.6° |
ϕ and ω scans | h = −9→9 |
5283 measured reflections | k = −7→7 |
1403 independent reflections | l = −18→18 |
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)] = 0.082 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.230 | H-atom parameters constrained |
S = 1.13 | w = 1/[σ2(Fo2) + (0.1065P)2 + 3.2641P] where P = (Fo2 + 2Fc2)/3 |
1403 reflections | (Δ/σ)max = 0.003 |
203 parameters | Δρmax = 0.37 e Å−3 |
2 restraints | Δρmin = −0.45 e Å−3 |
C15H25F2NO4 | V = 795.1 (2) Å3 |
Mr = 321.36 | Z = 2 |
Monoclinic, Pn | Mo Kα radiation |
a = 7.9651 (14) Å | µ = 0.11 mm−1 |
b = 6.4632 (12) Å | T = 150 K |
c = 15.445 (3) Å | 0.24 × 0.18 × 0.12 mm |
β = 90.136 (3)° |
Bruker APEX CCD area-detector diffractometer | 1332 reflections with I > 2σ(I) |
5283 measured reflections | Rint = 0.041 |
1403 independent reflections |
R[F2 > 2σ(F2)] = 0.082 | 2 restraints |
wR(F2) = 0.230 | H-atom parameters constrained |
S = 1.13 | Δρmax = 0.37 e Å−3 |
1403 reflections | Δρmin = −0.45 e Å−3 |
203 parameters |
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 | ||
F1 | 0.6752 (7) | 0.0571 (9) | 0.2519 (4) | 0.0344 (14) | |
F2 | 0.6142 (6) | 0.1799 (8) | 0.1254 (4) | 0.0293 (12) | |
O1 | 0.7967 (8) | 0.4476 (10) | 0.2290 (4) | 0.0285 (15) | |
H1 | 0.7144 | 0.4897 | 0.1998 | 0.043* | |
O2 | 0.6712 (8) | −0.2340 (10) | 0.1225 (4) | 0.0291 (15) | |
H2 | 0.7050 | −0.3474 | 0.1024 | 0.044* | |
O3 | 0.8718 (8) | 0.0997 (9) | 0.0008 (4) | 0.0249 (14) | |
O4 | 0.6287 (8) | −0.0565 (9) | −0.0385 (4) | 0.0253 (14) | |
N1 | 0.6973 (9) | 0.2608 (11) | −0.0879 (5) | 0.0228 (16) | |
C1 | 0.8721 (11) | 0.2781 (14) | 0.1864 (6) | 0.0243 (19) | |
H1A | 0.9126 | 0.3248 | 0.1284 | 0.029* | |
C2 | 0.7432 (12) | 0.1048 (15) | 0.1735 (6) | 0.026 (2) | |
C3 | 0.8118 (11) | −0.0981 (14) | 0.1351 (6) | 0.025 (2) | |
H3 | 0.8849 | −0.1626 | 0.1805 | 0.030* | |
C4 | 0.9179 (11) | −0.0828 (13) | 0.0516 (6) | 0.0227 (19) | |
H4 | 0.8865 | −0.2054 | 0.0155 | 0.027* | |
C5 | 1.1090 (11) | −0.0844 (14) | 0.0577 (6) | 0.0218 (19) | |
C5' | 1.1659 (12) | −0.2867 (15) | 0.1012 (7) | 0.033 (2) | |
H5'1 | 1.1501 | −0.2759 | 0.1640 | 0.050* | |
H5'2 | 1.2848 | −0.3109 | 0.0887 | 0.050* | |
H5'3 | 1.0990 | −0.4022 | 0.0788 | 0.050* | |
C5" | 1.1791 (12) | −0.0842 (16) | −0.0346 (7) | 0.032 (2) | |
H5"1 | 1.1315 | −0.2007 | −0.0670 | 0.047* | |
H5"2 | 1.3016 | −0.0975 | −0.0324 | 0.047* | |
H5"3 | 1.1490 | 0.0458 | −0.0634 | 0.047* | |
C6 | 1.1867 (11) | 0.1057 (15) | 0.1063 (7) | 0.029 (2) | |
H6A | 1.3097 | 0.1034 | 0.0973 | 0.034* | |
H6B | 1.1433 | 0.2334 | 0.0788 | 0.034* | |
C7 | 1.1546 (12) | 0.1196 (14) | 0.2009 (6) | 0.026 (2) | |
H7 | 1.2371 | 0.0628 | 0.2386 | 0.032* | |
C8 | 1.0180 (12) | 0.2062 (14) | 0.2379 (6) | 0.029 (2) | |
H8 | 1.0155 | 0.2214 | 0.2991 | 0.035* | |
C9 | 0.7223 (11) | 0.0905 (15) | −0.0430 (5) | 0.0227 (19) | |
C10 | 0.5307 (11) | 0.2911 (17) | −0.1285 (6) | 0.028 (2) | |
H10C | 0.4777 | 0.1548 | −0.1391 | 0.034* | |
H10D | 0.5444 | 0.3612 | −0.1850 | 0.034* | |
C10' | 0.8155 (11) | 0.4301 (14) | −0.0983 (6) | 0.024 (2) | |
H10A | 0.8889 | 0.4363 | −0.0465 | 0.029* | |
H10B | 0.7523 | 0.5617 | −0.1014 | 0.029* | |
C11 | 0.4178 (12) | 0.4201 (16) | −0.0708 (6) | 0.030 (2) | |
H11D | 0.4013 | 0.3486 | −0.0156 | 0.045* | |
H11E | 0.3090 | 0.4402 | −0.0994 | 0.045* | |
H11F | 0.4703 | 0.5550 | −0.0603 | 0.045* | |
C11' | 0.9211 (13) | 0.411 (2) | −0.1756 (8) | 0.041 (3) | |
H11A | 0.9914 | 0.2876 | −0.1708 | 0.061* | |
H11B | 0.9927 | 0.5341 | −0.1807 | 0.061* | |
H11C | 0.8495 | 0.4002 | −0.2271 | 0.061* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.044 (3) | 0.033 (3) | 0.027 (3) | −0.008 (3) | 0.013 (2) | 0.000 (2) |
F2 | 0.018 (2) | 0.031 (3) | 0.039 (3) | 0.006 (2) | −0.001 (2) | −0.002 (3) |
O1 | 0.033 (4) | 0.024 (3) | 0.029 (3) | 0.010 (3) | −0.002 (3) | −0.006 (3) |
O2 | 0.026 (3) | 0.021 (3) | 0.040 (4) | −0.010 (3) | 0.008 (3) | −0.007 (3) |
O3 | 0.022 (3) | 0.017 (3) | 0.036 (3) | 0.002 (3) | −0.007 (3) | 0.001 (3) |
O4 | 0.026 (3) | 0.021 (3) | 0.030 (3) | −0.002 (3) | −0.003 (3) | 0.001 (3) |
N1 | 0.030 (4) | 0.015 (4) | 0.024 (4) | 0.006 (3) | −0.005 (3) | −0.003 (3) |
C1 | 0.033 (5) | 0.022 (4) | 0.018 (4) | −0.004 (4) | 0.006 (4) | −0.006 (4) |
C2 | 0.028 (5) | 0.019 (5) | 0.030 (5) | 0.005 (4) | −0.001 (4) | 0.005 (4) |
C3 | 0.025 (5) | 0.022 (5) | 0.029 (5) | 0.000 (4) | −0.007 (4) | −0.001 (4) |
C4 | 0.024 (4) | 0.015 (4) | 0.029 (5) | 0.000 (3) | −0.004 (4) | 0.003 (4) |
C5 | 0.021 (4) | 0.021 (4) | 0.023 (4) | 0.002 (4) | 0.001 (4) | 0.006 (4) |
C5' | 0.032 (5) | 0.026 (5) | 0.042 (6) | 0.006 (4) | −0.007 (4) | 0.013 (4) |
C5" | 0.025 (5) | 0.033 (5) | 0.036 (5) | 0.000 (4) | 0.005 (4) | −0.001 (4) |
C6 | 0.014 (4) | 0.029 (5) | 0.044 (6) | −0.002 (4) | 0.005 (4) | −0.002 (4) |
C7 | 0.037 (5) | 0.021 (4) | 0.021 (5) | 0.001 (4) | −0.009 (4) | 0.003 (4) |
C8 | 0.037 (5) | 0.021 (5) | 0.028 (5) | −0.007 (4) | −0.006 (4) | −0.002 (4) |
C9 | 0.025 (4) | 0.032 (5) | 0.011 (4) | −0.004 (4) | −0.007 (3) | −0.004 (4) |
C10 | 0.021 (4) | 0.040 (6) | 0.024 (4) | −0.002 (4) | −0.001 (4) | −0.006 (4) |
C10' | 0.024 (5) | 0.023 (5) | 0.027 (5) | 0.008 (4) | −0.005 (4) | 0.002 (4) |
C11 | 0.025 (5) | 0.033 (5) | 0.032 (5) | 0.006 (4) | 0.008 (4) | 0.009 (4) |
C11' | 0.023 (5) | 0.051 (7) | 0.047 (6) | −0.007 (5) | 0.010 (5) | −0.009 (5) |
F1—C2 | 1.363 (11) | C5'—H5'2 | 0.980 |
F2—C2 | 1.356 (11) | C5'—H5'3 | 0.980 |
O1—C1 | 1.412 (10) | C5"—H5"1 | 0.980 |
O1—H1 | 0.840 | C5"—H5"2 | 0.980 |
O2—C3 | 1.437 (11) | C5"—H5"3 | 0.980 |
O2—H2 | 0.840 | C6—C7 | 1.487 (13) |
O3—C9 | 1.369 (11) | C6—H6A | 0.990 |
O3—C4 | 1.463 (10) | C6—H6B | 0.990 |
O4—C9 | 1.210 (11) | C7—C8 | 1.351 (14) |
N1—C9 | 1.315 (12) | C7—H7 | 0.950 |
N1—C10' | 1.453 (12) | C8—H8 | 0.950 |
N1—C10 | 1.480 (11) | C10—C11 | 1.517 (13) |
C1—C8 | 1.482 (13) | C10—H10C | 0.990 |
C1—C2 | 1.533 (13) | C10—H10D | 0.990 |
C1—H1A | 1.000 | C10'—C11' | 1.468 (14) |
C2—C3 | 1.540 (12) | C10'—H10A | 0.990 |
C3—C4 | 1.548 (13) | C10'—H10B | 0.990 |
C3—H3 | 1.000 | C11—H11D | 0.980 |
C4—C5 | 1.524 (12) | C11—H11E | 0.980 |
C4—H4 | 1.000 | C11—H11F | 0.980 |
C5—C5" | 1.532 (13) | C11'—H11A | 0.980 |
C5—C5' | 1.538 (12) | C11'—H11B | 0.980 |
C5—C6 | 1.567 (13) | C11'—H11C | 0.980 |
C5'—H5'1 | 0.980 | ||
C1—O1—H1 | 109.5 | H5"1—C5"—H5"2 | 109.5 |
C3—O2—H2 | 109.5 | C5—C5"—H5"3 | 109.5 |
C9—O3—C4 | 116.6 (7) | H5"1—C5"—H5"3 | 109.5 |
C9—N1—C10' | 126.2 (7) | H5"2—C5"—H5"3 | 109.5 |
C9—N1—C10 | 117.9 (8) | C7—C6—C5 | 116.7 (8) |
C10'—N1—C10 | 115.7 (7) | C7—C6—H6A | 108.1 |
O1—C1—C8 | 109.1 (7) | C5—C6—H6A | 108.1 |
O1—C1—C2 | 110.0 (7) | C7—C6—H6B | 108.1 |
C8—C1—C2 | 111.4 (8) | C5—C6—H6B | 108.1 |
O1—C1—H1A | 108.8 | H6A—C6—H6B | 107.3 |
C8—C1—H1A | 108.8 | C8—C7—C6 | 125.5 (8) |
C2—C1—H1A | 108.8 | C8—C7—H7 | 117.2 |
F2—C2—F1 | 105.4 (7) | C6—C7—H7 | 117.2 |
F2—C2—C1 | 108.4 (7) | C7—C8—C1 | 122.3 (8) |
F1—C2—C1 | 108.5 (7) | C7—C8—H8 | 118.9 |
F2—C2—C3 | 111.3 (7) | C1—C8—H8 | 118.9 |
F1—C2—C3 | 106.9 (7) | O4—C9—N1 | 126.5 (8) |
C1—C2—C3 | 115.7 (7) | O4—C9—O3 | 122.7 (8) |
O2—C3—C2 | 107.2 (7) | N1—C9—O3 | 110.7 (8) |
O2—C3—C4 | 110.6 (7) | N1—C10—C11 | 110.8 (8) |
C2—C3—C4 | 117.5 (8) | N1—C10—H10C | 109.5 |
O2—C3—H3 | 107.0 | C11—C10—H10C | 109.5 |
C2—C3—H3 | 107.0 | N1—C10—H10D | 109.5 |
C4—C3—H3 | 107.0 | C11—C10—H10D | 109.5 |
O3—C4—C5 | 106.7 (7) | H10C—C10—H10D | 108.1 |
O3—C4—C3 | 111.2 (7) | N1—C10'—C11' | 113.6 (8) |
C5—C4—C3 | 119.7 (7) | N1—C10'—H10A | 108.8 |
O3—C4—H4 | 106.1 | C11'—C10'—H10A | 108.8 |
C5—C4—H4 | 106.1 | N1—C10'—H10B | 108.8 |
C3—C4—H4 | 106.1 | C11'—C10'—H10B | 108.8 |
C4—C5—C5" | 107.9 (7) | H10A—C10'—H10B | 107.7 |
C4—C5—C5' | 109.0 (7) | C10—C11—H11D | 109.5 |
C5"—C5—C5' | 107.4 (8) | C10—C11—H11E | 109.5 |
C4—C5—C6 | 114.7 (7) | H11D—C11—H11E | 109.5 |
C5"—C5—C6 | 107.5 (7) | C10—C11—H11F | 109.5 |
C5'—C5—C6 | 110.0 (8) | H11D—C11—H11F | 109.5 |
C5—C5'—H5'1 | 109.5 | H11E—C11—H11F | 109.5 |
C5—C5'—H5'2 | 109.5 | C10'—C11'—H11A | 109.5 |
H5'1—C5'—H5'2 | 109.5 | C10'—C11'—H11B | 109.5 |
C5—C5'—H5'3 | 109.5 | H11A—C11'—H11B | 109.5 |
H5'1—C5'—H5'3 | 109.5 | C10'—C11'—H11C | 109.5 |
H5'2—C5'—H5'3 | 109.5 | H11A—C11'—H11C | 109.5 |
C5—C5"—H5"1 | 109.5 | H11B—C11'—H11C | 109.5 |
C5—C5"—H5"2 | 109.5 | ||
O1—C1—C2—F2 | 59.4 (9) | C3—C4—C5—C5' | 59.3 (11) |
C8—C1—C2—F2 | −179.4 (7) | O3—C4—C5—C6 | 62.8 (9) |
O1—C1—C2—F1 | −54.5 (9) | C3—C4—C5—C6 | −64.5 (11) |
C8—C1—C2—F1 | 66.6 (9) | C4—C5—C6—C7 | 68.2 (10) |
O1—C1—C2—C3 | −174.7 (7) | C5"—C5—C6—C7 | −171.7 (8) |
C8—C1—C2—C3 | −53.6 (10) | C5'—C5—C6—C7 | −55.0 (10) |
F2—C2—C3—O2 | −51.6 (9) | C5—C6—C7—C8 | −86.0 (12) |
F1—C2—C3—O2 | 63.0 (9) | C6—C7—C8—C1 | 7.2 (15) |
C1—C2—C3—O2 | −176.0 (7) | O1—C1—C8—C7 | −149.3 (9) |
F2—C2—C3—C4 | 73.6 (10) | C2—C1—C8—C7 | 89.1 (10) |
F1—C2—C3—C4 | −171.7 (7) | C10'—N1—C9—O4 | −175.1 (9) |
C1—C2—C3—C4 | −50.8 (11) | C10—N1—C9—O4 | 8.3 (13) |
C9—O3—C4—C5 | 153.8 (7) | C10'—N1—C9—O3 | 5.7 (12) |
C9—O3—C4—C3 | −74.1 (9) | C10—N1—C9—O3 | −170.9 (7) |
O2—C3—C4—O3 | 96.4 (8) | C4—O3—C9—O4 | 2.5 (12) |
C2—C3—C4—O3 | −27.1 (11) | C4—O3—C9—N1 | −178.3 (7) |
O2—C3—C4—C5 | −138.4 (8) | C9—N1—C10—C11 | 95.1 (10) |
C2—C3—C4—C5 | 98.1 (10) | C10'—N1—C10—C11 | −81.9 (10) |
O3—C4—C5—C5" | −57.0 (9) | C9—N1—C10'—C11' | 92.9 (11) |
C3—C4—C5—C5" | 175.8 (8) | C10—N1—C10'—C11' | −90.4 (10) |
O3—C4—C5—C5' | −173.4 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O2i | 0.84 | 2.18 | 2.816 (10) | 133 |
Symmetry code: (i) x, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C15H25F2NO4 |
Mr | 321.36 |
Crystal system, space group | Monoclinic, Pn |
Temperature (K) | 150 |
a, b, c (Å) | 7.9651 (14), 6.4632 (12), 15.445 (3) |
β (°) | 90.136 (3) |
V (Å3) | 795.1 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.24 × 0.18 × 0.12 |
Data collection | |
Diffractometer | Bruker APEX CCD area-detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5283, 1403, 1332 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.082, 0.230, 1.13 |
No. of reflections | 1403 |
No. of parameters | 203 |
No. of restraints | 2 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.37, −0.45 |
Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1999), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 2000), SHELXTL.
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O2i | 0.84 | 2.18 | 2.816 (10) | 133 |
Symmetry code: (i) x, y+1, z. |
Acknowledgements
The authors thank the Universities of Birmingham and Leicester, the EPSRC (project grant GR/K84882 for SP), GlaxoSmithKline (CASE studentship for SP) and Universities UK (ORS Award for EU).
References
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Conformational equilibria in eight-membered carbocycles occur via two main processes, pseudorotation and ring inversion. The latter exchanges substituent groups between equatorial and axial environments in a pseudo-enantiomeric relationship. Ring inversion is usually the more energetically demanding process; barriers to inversion exchange of 7.3–8.5 kcal mol−1 have been reported, with smaller barriers (ca 5 kcal mol−1) (Servis & Noe, 1973) for the pseudorotation. [For early attempts to apply variable-temperature NMR to these phenomena, see Anderson et al. (1969) and St Jacques et al. (1966).] Recent work from our group has attempted to define these processes for a trio of difluorinated cyclooctenyl systems (Griffith et al., 2005). We were interested to observe a pseudorotational relationship between the ring conformations in the pair of reduction products (1) and (2), obtained upon treatment of a precursor ketone with sodium borohydride.
Product (1) (the major product) arises from the opposite sense of hydride attack, with the N,N-diethylcarbamoyl group retaining its original location (Fig. 1). Product (2), reported in the following paper (Fawcett, Percy et al., 2005), arises from reagent attack on the ring face which bears the hydroxyl group, followed by migration of the N,N-diethylcarbamoyl group on to the newly formed hydroxyl group (Balnaves et al., 1999). A comparison of the two molecules is shown in Fig. 2. O—H···O hydrogen bonding links molecules of (1) into chains along the b axis (Table 1).