Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104014647/jz1616sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104014647/jz1616Isup2.hkl |
CCDC reference: 248169
For the preparation of (I), diethylmalonate (240 mg, 1.50 mmol) was added to a solution of butyllithium (780 µl, 1.95 mmol) and diisopropylamine (197 mg, 1.95 mmol) in dry dimethoxyethane (30 ml) cooled to 195 K. After 30 min, 2,2,6,6-tetramethylpiperidin-1-oxyl (328 mg, 2.10 mmol) was added. The reaction mixture was warmed slowly to 273 K and dry copper (II) chloride was added portionwise (large excess, until a green colour persisted) over a period 10 min. The reaction mixture was stirred at 273 K for 2 h, quenched with saturated ammonium chloride solution (10 ml) and extracted with ether (3 × 25 ml). The combined organic layer was washed with water (5 × 100 ml), dried over Na2SO4 (anhydrous) and concentrated under reduced pressure. The crude product was purified by flash column chromatography with 2% ethyl acetate in hexane as eluant, yielding a colourless low-melting solid (m.p. 301–303 K). IR (cm−1, KBr): 2977, 2935, 1767, 1746, 1468, 1367, 1213, 1183, 1097, 1028, 960; 1H NMR (200 MHz, CDCl3): δ 1.08, 1.20 (2 s, 12H, CH3), 1.29, (t, J = 7.1 Hz, 6H, CH3), 1.46 (bs, 6H, CH2), 4.20–4.27 (m, 4H, CH2), 4.92 (s, 1H, CH); 13C NMR (50 MHz, CDCl3): δ 15.1, 18.0, 21.1, 33.6, 41.1, 61.3, 62.6, 87.7, 168.3. Analysis calculated for C16H29NO5: C 60.93, H 9.27, N 4.44%; found: C 61.04, H 9.38, N 4.57%. For the preparation of (II), lithium aluminium hydride (133 mg, 3.50 mmol) was added to a solution of (1) (420 mg, 1.30 mmol) in 20 ml of dry THF at 273 K. After 1 h, ethyl acetate (15 ml) was added to the reaction mixture at 273 K. After 30 min, the reaction mixture was poured into water and extracted with dichloromethane (3 × 25 ml). The combined organic layer was dried over Na2SO4 (anhydrous) and concentrated under reduced pressure. The crude product was purified by flash column chromatography with 50% ethyl acetate in hexane as eluant, yielding a colourless solid (m.p. 354 K). IR (cm−1, KBr): 3310, 2920, 1360, 1244, 1133, 1112, 1094, 1039, 975, 959; 1H NMR (200 MHz, CDCl3): δ 1.15, 1.33 (2 s, 12H, CH3), 1.52 (bs, 6H, CH2), 3.61 (bs, 4H, CH2 and OH), 3.83 (t, J = 7.1 Hz, 2H, CH2), 4.38 (t, J = 7.1 Hz, 1H, CH); 13C NMR (50 MHz, CDCl3): δ 18.0, 21.3, 34.5, 41.2, 61.9, 65.1, 82.0. Analysis calculated for C12H25NO3: C 62.30, H 10.89, N 6.05%; found C 61.70, H 11.17, N 5.99%. Single crystals of (II) suitable for X-ray analysis were obtained upon evaporation of the solvent (hexane:ethylacetate, 50%) under reduced pressure (313 K).
C-bound H atoms were placed in idealized positions and included in the refinement as riding atoms, with Uiso(H) values of 1.2Ueq of the parent C atoms. The positions of the hydroxy H atoms were found from difference Fourier maps and refined, with Uiso(H) values fixed to 1.5Ueq of the parent O atoms.
Data collection: EXPOSE in IPDS Software (Stoe & Cie, 1999); cell refinement: CELL and SELECT in IPDS Software; data reduction: X-RED (Stoe & Cie, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Crystal Impact, 1999); software used to prepare material for publication: enCIFer (Allen et al., 2004).
C12H25NO3 | F(000) = 512 |
Mr = 231.33 | Dx = 1.162 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 8000 reflections |
a = 14.6525 (13) Å | θ = 2.8–30.4° |
b = 14.6357 (8) Å | µ = 0.08 mm−1 |
c = 6.1793 (5) Å | T = 173 K |
β = 93.801 (10)° | Needles, colourless |
V = 1322.23 (17) Å3 | 0.2 × 0.1 × 0.08 mm |
Z = 4 |
Stoe IPDS diffractometer | 2635 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.043 |
Graphite monochromator | θmax = 30.5°, θmin = 3.1° |
143 exposures, Δϕ=1.4° scans | h = −20→20 |
15527 measured reflections | k = −20→19 |
3992 independent reflections | l = −8→8 |
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)] = 0.036 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.093 | w = 1/[σ2(Fo2) + (0.0619P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.93 | (Δ/σ)max < 0.001 |
3992 reflections | Δρmax = 0.25 e Å−3 |
158 parameters | Δρmin = −0.19 e Å−3 |
0 restraints | Extinction correction: SHELXL97 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.019 (2) |
C12H25NO3 | V = 1322.23 (17) Å3 |
Mr = 231.33 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 14.6525 (13) Å | µ = 0.08 mm−1 |
b = 14.6357 (8) Å | T = 173 K |
c = 6.1793 (5) Å | 0.2 × 0.1 × 0.08 mm |
β = 93.801 (10)° |
Stoe IPDS diffractometer | 2635 reflections with I > 2σ(I) |
15527 measured reflections | Rint = 0.043 |
3992 independent reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.093 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.93 | Δρmax = 0.25 e Å−3 |
3992 reflections | Δρmin = −0.19 e Å−3 |
158 parameters |
Experimental. M·P. 81 °C. IR cm−1 (KBr): 3310, 2920, 1360, 1244, 1133, 1112, 1094, 1039, 975, 959. 1H-NMR (200 MHz, CDCl3): δ in p.p.m., 1.15, 1.33 (2 s, 12H, CH3), 1.52 (bs, 6H, CH2), 3.61 (bs, 4H, CH2 & OH), 3.83 (t, J = 7.1 Hz, 2H, CH2), 4.38 (t, J = 7.1 Hz, 1H, CH). 13C-NMR (50 MHz, CDCl3): δ in p.p.m., 18.0, 21.3, 34.5, 41.2, 61.9, 65.1, 82.0. EA (C12H25NO3): Calculated C 62.30, H 10.89, N 6.05, Found C 61.70, 11.17, 5.99. |
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 | ||
N1 | 0.83695 (5) | 0.19447 (5) | 0.09459 (13) | 0.01920 (17) | |
O1 | 0.87895 (4) | 0.28244 (4) | 0.15085 (10) | 0.01944 (15) | |
O2 | 0.93334 (5) | 0.40403 (5) | −0.35090 (11) | 0.02823 (18) | |
H2 | 0.9614 (10) | 0.4535 (10) | −0.303 (2) | 0.042* | |
O3 | 0.97076 (5) | 0.44377 (5) | 0.22922 (11) | 0.02349 (16) | |
H3 | 0.9485 (9) | 0.4193 (9) | 0.340 (2) | 0.035* | |
C1 | 0.73809 (6) | 0.20290 (7) | 0.14236 (16) | 0.0225 (2) | |
C2 | 0.69463 (7) | 0.10860 (7) | 0.0970 (2) | 0.0314 (2) | |
H2A | 0.6300 | 0.1105 | 0.1342 | 0.038* | |
H2B | 0.6953 | 0.0953 | −0.0600 | 0.038* | |
C3 | 0.74314 (8) | 0.03201 (8) | 0.2232 (2) | 0.0393 (3) | |
H3A | 0.7143 | −0.0273 | 0.1826 | 0.047* | |
H3B | 0.7382 | 0.0415 | 0.3806 | 0.047* | |
C4 | 0.84318 (8) | 0.03101 (7) | 0.1719 (2) | 0.0356 (3) | |
H4A | 0.8472 | 0.0155 | 0.0169 | 0.043* | |
H4B | 0.8753 | −0.0175 | 0.2589 | 0.043* | |
C5 | 0.89214 (7) | 0.12252 (7) | 0.21828 (17) | 0.0246 (2) | |
C6 | 0.93335 (6) | 0.31733 (6) | −0.01723 (14) | 0.01936 (18) | |
H6 | 0.9619 | 0.2649 | −0.0916 | 0.023* | |
C7 | 0.87718 (7) | 0.37361 (7) | −0.18464 (16) | 0.0233 (2) | |
H7A | 0.8262 | 0.3361 | −0.2497 | 0.028* | |
H7B | 0.8507 | 0.4271 | −0.1133 | 0.028* | |
C8 | 1.00801 (6) | 0.37259 (6) | 0.10436 (16) | 0.02108 (19) | |
H8A | 1.0455 | 0.3316 | 0.2017 | 0.025* | |
H8B | 1.0485 | 0.3996 | −0.0008 | 0.025* | |
C9 | 0.69230 (7) | 0.27123 (8) | −0.01684 (18) | 0.0282 (2) | |
H9A | 0.7163 | 0.3326 | 0.0152 | 0.034* | |
H9B | 0.6261 | 0.2707 | −0.0027 | 0.034* | |
H9C | 0.7051 | 0.2542 | −0.1652 | 0.034* | |
C10 | 0.72040 (7) | 0.23651 (8) | 0.37195 (17) | 0.0303 (2) | |
H10A | 0.7340 | 0.1872 | 0.4765 | 0.036* | |
H10B | 0.6562 | 0.2546 | 0.3765 | 0.036* | |
H10C | 0.7598 | 0.2891 | 0.4089 | 0.036* | |
C11 | 0.98569 (7) | 0.11664 (7) | 0.12177 (19) | 0.0290 (2) | |
H11A | 0.9771 | 0.1122 | −0.0365 | 0.035* | |
H11B | 1.0184 | 0.0624 | 0.1789 | 0.035* | |
H11C | 1.0214 | 0.1715 | 0.1613 | 0.035* | |
C12 | 0.90958 (8) | 0.13938 (8) | 0.46359 (18) | 0.0347 (3) | |
H12A | 0.9248 | 0.2039 | 0.4890 | 0.042* | |
H12B | 0.9606 | 0.1011 | 0.5203 | 0.042* | |
H12C | 0.8545 | 0.1239 | 0.5375 | 0.042* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0186 (3) | 0.0187 (4) | 0.0204 (4) | −0.0051 (3) | 0.0015 (3) | −0.0027 (3) |
O1 | 0.0233 (3) | 0.0193 (3) | 0.0160 (3) | −0.0070 (2) | 0.0036 (2) | −0.0028 (3) |
O2 | 0.0402 (4) | 0.0294 (4) | 0.0155 (3) | −0.0138 (3) | 0.0047 (3) | −0.0014 (3) |
O3 | 0.0307 (3) | 0.0229 (3) | 0.0173 (3) | −0.0085 (3) | 0.0049 (3) | −0.0022 (3) |
C1 | 0.0191 (4) | 0.0286 (5) | 0.0200 (4) | −0.0043 (3) | 0.0033 (3) | −0.0021 (4) |
C2 | 0.0232 (5) | 0.0347 (6) | 0.0364 (6) | −0.0105 (4) | 0.0043 (4) | −0.0040 (5) |
C3 | 0.0344 (6) | 0.0290 (5) | 0.0550 (8) | −0.0130 (4) | 0.0068 (5) | 0.0037 (5) |
C4 | 0.0328 (5) | 0.0227 (5) | 0.0514 (7) | −0.0052 (4) | 0.0035 (5) | 0.0028 (5) |
C5 | 0.0241 (5) | 0.0216 (4) | 0.0280 (5) | −0.0023 (4) | 0.0018 (4) | 0.0033 (4) |
C6 | 0.0207 (4) | 0.0210 (4) | 0.0169 (4) | −0.0041 (3) | 0.0052 (3) | −0.0009 (4) |
C7 | 0.0253 (4) | 0.0286 (5) | 0.0158 (4) | −0.0062 (4) | 0.0007 (3) | 0.0004 (4) |
C8 | 0.0190 (4) | 0.0239 (4) | 0.0203 (4) | −0.0023 (3) | 0.0013 (3) | 0.0011 (4) |
C9 | 0.0204 (4) | 0.0380 (5) | 0.0259 (5) | −0.0001 (4) | 0.0007 (4) | −0.0001 (5) |
C10 | 0.0277 (5) | 0.0413 (6) | 0.0228 (5) | −0.0026 (4) | 0.0083 (4) | −0.0033 (5) |
C11 | 0.0246 (5) | 0.0243 (5) | 0.0380 (6) | 0.0012 (4) | 0.0020 (4) | 0.0003 (4) |
C12 | 0.0353 (6) | 0.0421 (6) | 0.0262 (5) | 0.0007 (5) | −0.0018 (4) | 0.0087 (5) |
N1—O1 | 1.4591 (9) | C5—C12 | 1.5403 (16) |
N1—C1 | 1.5024 (12) | C6—C8 | 1.5187 (13) |
N1—C5 | 1.5050 (13) | C6—C7 | 1.5209 (13) |
O1—C6 | 1.4438 (10) | C6—H6 | 1.0000 |
O2—C7 | 1.4293 (12) | C7—H7A | 0.9900 |
O2—H2 | 0.873 (15) | C7—H7B | 0.9900 |
O3—C8 | 1.4263 (12) | C8—H8A | 0.9900 |
O3—H3 | 0.855 (15) | C8—H8B | 0.9900 |
C1—C9 | 1.5266 (14) | C9—H9A | 0.9800 |
C1—C2 | 1.5380 (14) | C9—H9B | 0.9800 |
C1—C10 | 1.5397 (14) | C9—H9C | 0.9800 |
C2—C3 | 1.5155 (17) | C10—H10A | 0.9800 |
C2—H2A | 0.9900 | C10—H10B | 0.9800 |
C2—H2B | 0.9900 | C10—H10C | 0.9800 |
C3—C4 | 1.5201 (16) | C11—H11A | 0.9800 |
C3—H3A | 0.9900 | C11—H11B | 0.9800 |
C3—H3B | 0.9900 | C11—H11C | 0.9800 |
C4—C5 | 1.5374 (14) | C12—H12A | 0.9800 |
C4—H4A | 0.9900 | C12—H12B | 0.9800 |
C4—H4B | 0.9900 | C12—H12C | 0.9800 |
C5—C11 | 1.5330 (14) | ||
O1—N1—C1 | 106.12 (6) | O1—C6—H6 | 109.1 |
O1—N1—C5 | 107.00 (7) | C8—C6—H6 | 109.1 |
C1—N1—C5 | 116.76 (7) | C7—C6—H6 | 109.1 |
C6—O1—N1 | 112.64 (6) | O2—C7—C6 | 110.25 (8) |
C7—O2—H2 | 107.2 (10) | O2—C7—H7A | 109.6 |
C8—O3—H3 | 107.8 (9) | C6—C7—H7A | 109.6 |
N1—C1—C9 | 108.39 (7) | O2—C7—H7B | 109.6 |
N1—C1—C2 | 106.46 (8) | C6—C7—H7B | 109.6 |
C9—C1—C2 | 108.14 (8) | H7A—C7—H7B | 108.1 |
N1—C1—C10 | 115.51 (8) | O3—C8—C6 | 111.57 (7) |
C9—C1—C10 | 106.91 (8) | O3—C8—H8A | 109.3 |
C2—C1—C10 | 111.21 (8) | C6—C8—H8A | 109.3 |
C3—C2—C1 | 113.30 (9) | O3—C8—H8B | 109.3 |
C3—C2—H2A | 108.9 | C6—C8—H8B | 109.3 |
C1—C2—H2A | 108.9 | H8A—C8—H8B | 108.0 |
C3—C2—H2B | 108.9 | C1—C9—H9A | 109.5 |
C1—C2—H2B | 108.9 | C1—C9—H9B | 109.5 |
H2A—C2—H2B | 107.7 | H9A—C9—H9B | 109.5 |
C2—C3—C4 | 109.01 (9) | C1—C9—H9C | 109.5 |
C2—C3—H3A | 109.9 | H9A—C9—H9C | 109.5 |
C4—C3—H3A | 109.9 | H9B—C9—H9C | 109.5 |
C2—C3—H3B | 109.9 | C1—C10—H10A | 109.5 |
C4—C3—H3B | 109.9 | C1—C10—H10B | 109.5 |
H3A—C3—H3B | 108.3 | H10A—C10—H10B | 109.5 |
C3—C4—C5 | 113.41 (9) | C1—C10—H10C | 109.5 |
C3—C4—H4A | 108.9 | H10A—C10—H10C | 109.5 |
C5—C4—H4A | 108.9 | H10B—C10—H10C | 109.5 |
C3—C4—H4B | 108.9 | C5—C11—H11A | 109.5 |
C5—C4—H4B | 108.9 | C5—C11—H11B | 109.5 |
H4A—C4—H4B | 107.7 | H11A—C11—H11B | 109.5 |
N1—C5—C11 | 107.81 (8) | C5—C11—H11C | 109.5 |
N1—C5—C4 | 106.65 (8) | H11A—C11—H11C | 109.5 |
C11—C5—C4 | 107.27 (9) | H11B—C11—H11C | 109.5 |
N1—C5—C12 | 115.86 (8) | C5—C12—H12A | 109.5 |
C11—C5—C12 | 107.31 (8) | C5—C12—H12B | 109.5 |
C4—C5—C12 | 111.59 (9) | H12A—C12—H12B | 109.5 |
O1—C6—C8 | 104.26 (7) | C5—C12—H12C | 109.5 |
O1—C6—C7 | 112.41 (7) | H12A—C12—H12C | 109.5 |
C8—C6—C7 | 112.81 (8) | H12B—C12—H12C | 109.5 |
C1—N1—O1—C6 | −131.78 (7) | C1—N1—C5—C11 | 172.01 (8) |
C5—N1—O1—C6 | 102.87 (8) | O1—N1—C5—C4 | 175.73 (8) |
O1—N1—C1—C9 | 67.31 (9) | C1—N1—C5—C4 | 57.08 (11) |
C5—N1—C1—C9 | −173.57 (8) | O1—N1—C5—C12 | 50.86 (10) |
O1—N1—C1—C2 | −176.56 (7) | C1—N1—C5—C12 | −67.79 (11) |
C5—N1—C1—C2 | −57.44 (10) | C3—C4—C5—N1 | −54.73 (12) |
O1—N1—C1—C10 | −52.58 (10) | C3—C4—C5—C11 | −170.02 (10) |
C5—N1—C1—C10 | 66.55 (11) | C3—C4—C5—C12 | 72.71 (12) |
N1—C1—C2—C3 | 55.63 (11) | N1—O1—C6—C8 | −149.61 (7) |
C9—C1—C2—C3 | 171.93 (9) | N1—O1—C6—C7 | 87.88 (9) |
C10—C1—C2—C3 | −70.98 (11) | O1—C6—C7—O2 | −178.12 (7) |
C1—C2—C3—C4 | −56.80 (13) | C8—C6—C7—O2 | 64.33 (10) |
C2—C3—C4—C5 | 56.36 (14) | O1—C6—C8—O3 | −58.52 (9) |
O1—N1—C5—C11 | −69.35 (9) | C7—C6—C8—O3 | 63.73 (10) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O3 | 0.873 (15) | 3.287 (15) | 3.6371 (10) | 106.8 (11) |
C10—H10C···O1 | 0.98 | 2.44 | 2.8524 (12) | 105 |
C12—H12A···O1 | 0.98 | 2.44 | 2.8645 (13) | 106 |
O2—H2···O3i | 0.873 (15) | 1.844 (15) | 2.7133 (10) | 173.3 (14) |
O3—H3···O2ii | 0.855 (15) | 1.952 (15) | 2.7494 (10) | 154.8 (13) |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y, z+1. |
Experimental details
Crystal data | |
Chemical formula | C12H25NO3 |
Mr | 231.33 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 173 |
a, b, c (Å) | 14.6525 (13), 14.6357 (8), 6.1793 (5) |
β (°) | 93.801 (10) |
V (Å3) | 1322.23 (17) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.2 × 0.1 × 0.08 |
Data collection | |
Diffractometer | Stoe IPDS diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15527, 3992, 2635 |
Rint | 0.043 |
(sin θ/λ)max (Å−1) | 0.713 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.093, 0.93 |
No. of reflections | 3992 |
No. of parameters | 158 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.25, −0.19 |
Computer programs: EXPOSE in IPDS Software (Stoe & Cie, 1999), CELL and SELECT in IPDS Software, X-RED (Stoe & Cie, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Crystal Impact, 1999), enCIFer (Allen et al., 2004).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O3 | 0.873 (15) | 3.287 (15) | 3.6371 (10) | 106.8 (11) |
C10—H10C···O1 | 0.98 | 2.44 | 2.8524 (12) | 105 |
C12—H12A···O1 | 0.98 | 2.44 | 2.8645 (13) | 106 |
O2—H2···O3i | 0.873 (15) | 1.844 (15) | 2.7133 (10) | 173.3 (14) |
O3—H3···O2ii | 0.855 (15) | 1.952 (15) | 2.7494 (10) | 154.8 (13) |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x, y, z+1. |
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Hydrogen-bonding motifs play an important role in the interaction, recognition and conformation of both small and large molecules (e.g. in biologically active molecules (Watson & Crick, 1953; Zeng et al., 2000)). These motifs have frequently been used as supramolecular synthons to direct solid-state structures (crystal engineering; Steiner, 2002; Aakeröy & Seddon, 1993) and for synthesis of complex supramolecules. The predictability of such interactions (N—H···N, N—H···O, O—H···N and O—H···O bonds) depends on the robustness and reproducibility of such interactions.
Simple dialcohols are increasingly becoming important synthons for the preparation of unidirectional architectures, such as ladders, in the solid state (Nguyen et al., 2001; Schmittel et al., 2003). Depending on the arrangement of the rung region, ladders usually adopt two distinct shapes, with a clear distinction between the `staircase' or the `step ladder' types. In staircase ladders, the rung region is made up of chains of (OH)n groups, while in step ladders, it contains discrete (OH)4 rings.
Unfortunately, there is no general trend in the substitution pattern that would enable us to exploit hydrogen-bonding interactions for building ladder structures, except that 1,3-diols tend to form ladder-like structures more easily than 1,2-diols; furthermore, racemic, achiral or 2-substituted 1,3-propane diols form step ladders.
From a Newman projection analysis of 1,3-diols known to form ladders (Nguyen et al., 2001), it appears that the antiperiplanar conformation leads to chain structures, whereas in the synclinal conformation, ladder-like structures are preferred (Chart 1: Newman projection analysis of hydrogen bonding interactions of diols leading either to a chain or ladder like structure.)
Our long-standing interest in building highly ordered and predictable supramolecular aggregates based on metal complexation (Schmittel et al., 2002a; Schmittel et al., 2002b; Schmittel et al., 2001) and more recently on hydrogen-bonded motifs (Schmittel et al. 2003) encouraged us to synthesize the achiral 1,3-diol (II) [2-(2,2,6,6-tetramethylpiperidin-1-yloxy)propane-1,3-diol] and to investigate its structural properties.
Compound (II) was prepared in reasonable yields starting from diethylmalonate via a method involving an initial trapping of a carbon- centred radical by the 2,2,6,6-tetramethylpiperidin-1-yloxy radical (Jahn et al., 2002) followed by lithium aluminium hydride reduction of diethyl-2-(2,2,6,6-tetramethylpiperidin-1-yloxy)malonate, (I) (Chart 2).
The crystal structure shows one molecule in the asymmetric unit. The piperidinoxy ring adopts the usual chair conformation. Atom O1 is antiperiplanar with atom O2 [−178.12 (s.u.?)°], whereas it is synclinal with atom O3 [−58.52 (s.u.?) °; Fig. 1]. Intramolecular C—H···O interactions (H···O = 2.44 Å) were observed between the axial methyl groups of the piperidinoxy group (C10 and C12) and atoms O1.
Intermolecular O—H···O hydrogen-bonding interactions predominate in the extended structure of (II); the primary O atoms act as both acceptor and donor (Table 1). The net effect is to connect the molecules into a chain structure parallel to [001], with a C11(6) graph set designator; two such chains are linked to form a two-dimensional hydrogen-bonding network with a supramolecular ladder-like arrangement (Fig. 2), as expected of a symmetrically substituted achiral 1,3-diol, with (OH)4 rings in the rung region. The intrastrand O···O distance [A = 2.7494 (10) Å; Fig. 2 and Table 1] is slightly greater than the interstrand O···O distance [B = 2.7133 (10) Å; Fig. 2 and Table 1], and the same is necessarily true of the H···O distances; the interstrand hydrogen bonding is thus presumably slightly stronger. The intramolecular O···O distance (C) is about 3.6371 (10) Å (Fig. 2 and Table 1), which is in the usual range for step-ladder motifs (Nguyen et al., 2001).