Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110026879/gd3351sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270110026879/gd3351Isup2.hkl |
CCDC reference: 790649
For related structures, see Blakemore et al. (2001), Ferey et al. (1996), Lam et al. (2002), Gainsford & Bowden (2009). For ring conformations see: Cremer & Pople (1975) For calculation and graphics software, see: Spek (2009), Farrugia (1997), Macrae et al. (2008). For hydrogen bond motifs, see: Bernstein et al. (1995).
To an argon-blanketed solution of the (+)-silylated lactam ester (19.1 g, 50.7 mmol) in dry THF [THF = tetrahydrofuran?] (230 ml), cooled in an ice bath, was added, dropwise, BH3.SMe2 (25 ml, 253.5 mmol) over a period of about 10 min. The solution was then warmed to 341 K and maintained as such for 16 h before being cooled (in ice) and quenched with excess methanol. The solution was concentrated and then fractionated by flash column chromatography on silica [10-->20% EtOAc/hexane] to give the (+)-pyrrolidine (9.38 g, 57%) as a colourless solid. m.p. 353 K (uncorr.), [α]D23 +29.4 (c 0.895, MeOH). FTIR (neat) υmax 3505 (OH), 2953, 2931, 2883, 2857, 2406, 2322 (BH3), 2267 (BH3), 1464, 1252, 1163 (N—B), 1083, 1063, 1049, 1025, 1010, 978, 933, 903, 868, 837, 821, 803, 774, 701, 669 cm-1. 1H NMR (500 MHz, CDCl3) δ 7.43–7.36 (m, 5H), 4.82 (q, 6.5 Hz, 1H), 4.06 (ABq, 12.9 Hz, 2H), 3.83 (dt, 12.0, 2.9 Hz, 1H), 3.53–3.48 (m, 1H), 3.39 (dd, 10.6, 6.5 Hz, 1H), 3.25 (t, 10.5 Hz, 1H), 3.15 (m, 1H) 2.91–2.84 (m, 1H), 2.66 (dd, 10.6, 6.5 Hz, 1H), 2.32 (dd, 9.8, 3.3 Hz, 1H), 0.88 (s, 9H), 0.11 (s, 3H), 0.07 (s, 3H) p.p.m. 13C NMR (125 MHz, CDCl3) δ 132.58, 131.35, 129.03, 128.20, 72.92, 67.46, 67.14, 60.23, 59.39, 41.78, 25.70, 17.85, -4.76, -5.18 p.p.m. 11B NMR (160 MHz, CDCl3) δ -10.3 p.p.m. HR ESMS MH+ m/z 322.2197 C18H22NO2Si requires MH+ m/z 322.2202 Δ 1.6 p.p.m.; MNa+ m/z 344.2021 C18H31NO2SiNa requires 344.2022 Δ 0.3 p.p.m.; MBH3Na+ 358 a.m.u. Microanalysis (%) found: C, 64.69; H, 10.76; N 4.17. C18H34BNO2Si requires C, 64.48; H, 10.15; N, 4.18.
Two low-angle reflections affected by the backstop were removed from the refinement. Conformational disorder involving phenyl plane orientations was modelled via linked occupancies of two rigid hexagonal phenyl groups (C—C 1.390 Å, atoms C6–C11; see Fig. 1): final occupancies for the a:b set were 0.65 (2):0.35 (2). Each a,b set of phenyl group C atoms were refined with the same anisotropic thermal parameters (using the SHELXL EADP function). The data would not support two independent sites for atom C1; two sets of bound H atoms (H1A, H1B; H1C, H1D) were calculated, given a,b occupancies as appropriate and fixed positionally. The C1—C6A and C1—C6B distances were restrained to be equal (SHELXL SADI function with effective standard deviation of 0.005 Å). The borane and hydroxyl H atoms were located on difference Fourier maps and refined with isotropic thermal parameters.
The methyl H atoms were constrained to an ideal geometry (C—H = 0.98 Å) with Uiso(H) = 1.5Ueq(C), but were allowed to rotate freely about the adjacent C—C bond. All other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H distances of 1.00 (primary), 0.99 (methylene) or 0.95 Å (phenyl). The phenyl H atoms were refined with Uiso(H) = 1.5Ueq(C); the remainder with Uiso(H) = 1.2Ueq(C).
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT and SADABS (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008); PLATON (Spek, 2009).
C18H34BNO2Si | F(000) = 736 |
Mr = 335.36 | Dx = 1.074 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 9852 reflections |
a = 7.8078 (7) Å | θ = 3.1–27.5° |
b = 11.2328 (10) Å | µ = 0.12 mm−1 |
c = 23.639 (2) Å | T = 113 K |
V = 2073.2 (3) Å3 | Block, colourless |
Z = 4 | 0.65 × 0.60 × 0.30 mm |
Bruker APEXII CCD diffractometer | 4901 independent reflections |
Radiation source: fine-focus sealed tube | 4409 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.089 |
Detector resolution: 8.333 pixels mm-1 | θmax = 28.0°, θmin = 2.5° |
ϕ and ω scans | h = −10→10 |
Absorption correction: multi-scan (Blessing, 1995) | k = −14→14 |
Tmin = 0.418, Tmax = 0.746 | l = −30→31 |
42018 measured reflections |
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.049 | w = 1/[σ2(Fo2) + (0.0861P)2 + 0.2024P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.134 | (Δ/σ)max = 0.001 |
S = 1.07 | Δρmax = 0.63 e Å−3 |
4901 reflections | Δρmin = −0.44 e Å−3 |
225 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
1 restraint | Extinction coefficient: 0.014 (2) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack (1983), 2102 Friedel pairs |
Secondary atom site location: difference Fourier map | Absolute structure parameter: 0.07 (13) |
C18H34BNO2Si | V = 2073.2 (3) Å3 |
Mr = 335.36 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.8078 (7) Å | µ = 0.12 mm−1 |
b = 11.2328 (10) Å | T = 113 K |
c = 23.639 (2) Å | 0.65 × 0.60 × 0.30 mm |
Bruker APEXII CCD diffractometer | 4901 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 4409 reflections with I > 2σ(I) |
Tmin = 0.418, Tmax = 0.746 | Rint = 0.089 |
42018 measured reflections |
R[F2 > 2σ(F2)] = 0.049 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.134 | Δρmax = 0.63 e Å−3 |
S = 1.07 | Δρmin = −0.44 e Å−3 |
4901 reflections | Absolute structure: Flack (1983), 2102 Friedel pairs |
225 parameters | Absolute structure parameter: 0.07 (13) |
1 restraint |
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 | Occ. (<1) | |
Si1 | 0.19313 (6) | 0.36108 (4) | 0.90701 (2) | 0.02300 (14) | |
O1 | 0.24122 (17) | 0.46153 (11) | 0.85794 (5) | 0.0234 (3) | |
O2 | −0.1258 (2) | 0.49256 (18) | 0.78076 (8) | 0.0459 (4) | |
H2 | −0.186 (4) | 0.448 (3) | 0.7566 (14) | 0.069* | |
N1 | 0.3916 (2) | 0.70105 (14) | 0.82291 (6) | 0.0240 (3) | |
C1 | 0.5692 (2) | 0.64733 (17) | 0.82715 (8) | 0.0252 (4) | |
C2 | 0.2826 (2) | 0.67121 (16) | 0.87428 (7) | 0.0236 (4) | |
H2A | 0.3555 | 0.6424 | 0.9057 | 0.028* | |
H2B | 0.2192 | 0.7425 | 0.8873 | 0.028* | |
C3 | 0.1588 (2) | 0.57473 (16) | 0.85575 (7) | 0.0227 (4) | |
H3 | 0.0514 | 0.5757 | 0.8788 | 0.027* | |
C4 | 0.1243 (3) | 0.60854 (18) | 0.79376 (8) | 0.0284 (4) | |
H4 | 0.0497 | 0.6809 | 0.7928 | 0.034* | |
C5 | 0.3025 (3) | 0.64194 (18) | 0.77299 (8) | 0.0297 (4) | |
H5A | 0.2950 | 0.6976 | 0.7406 | 0.036* | |
H5B | 0.3661 | 0.5701 | 0.7609 | 0.036* | |
C12 | 0.0412 (3) | 0.5112 (2) | 0.75898 (9) | 0.0341 (5) | |
H12A | 0.0350 | 0.5354 | 0.7188 | 0.041* | |
H12B | 0.1090 | 0.4370 | 0.7616 | 0.041* | |
C13 | 0.2448 (3) | 0.42308 (19) | 0.97843 (8) | 0.0371 (5) | |
H13A | 0.1848 | 0.4989 | 0.9836 | 0.056* | |
H13B | 0.3686 | 0.4361 | 0.9814 | 0.056* | |
H13C | 0.2081 | 0.3667 | 1.0077 | 0.056* | |
C15 | 0.3296 (3) | 0.22853 (16) | 0.88877 (8) | 0.0271 (4) | |
C16 | 0.2894 (4) | 0.1871 (2) | 0.82863 (10) | 0.0428 (6) | |
H16A | 0.3611 | 0.1182 | 0.8193 | 0.064* | |
H16B | 0.3130 | 0.2519 | 0.8020 | 0.064* | |
H16C | 0.1684 | 0.1646 | 0.8261 | 0.064* | |
C18 | 0.2936 (4) | 0.12692 (18) | 0.93078 (10) | 0.0429 (6) | |
H18A | 0.3601 | 0.0565 | 0.9199 | 0.064* | |
H18B | 0.1712 | 0.1076 | 0.9302 | 0.064* | |
H18C | 0.3266 | 0.1520 | 0.9690 | 0.064* | |
C14 | −0.0388 (3) | 0.3239 (2) | 0.90344 (12) | 0.0438 (6) | |
H14A | −0.0713 | 0.3090 | 0.8640 | 0.066* | |
H14B | −0.1060 | 0.3905 | 0.9183 | 0.066* | |
H14C | −0.0613 | 0.2525 | 0.9261 | 0.066* | |
C17 | 0.5203 (3) | 0.2607 (2) | 0.89198 (12) | 0.0436 (6) | |
H17A | 0.5453 | 0.3245 | 0.8649 | 0.065* | |
H17B | 0.5893 | 0.1904 | 0.8827 | 0.065* | |
H17C | 0.5481 | 0.2876 | 0.9303 | 0.065* | |
B1 | 0.3945 (4) | 0.8448 (2) | 0.81456 (11) | 0.0374 (6) | |
H1B1 | 0.246 (3) | 0.866 (2) | 0.8036 (11) | 0.045 (7)* | |
H2B1 | 0.444 (3) | 0.886 (2) | 0.8538 (10) | 0.030 (6)* | |
H3B1 | 0.485 (3) | 0.865 (2) | 0.7766 (10) | 0.033 (6)* | |
H1A | 0.6324 | 0.6683 | 0.7923 | 0.024 (4)* | 0.65 (2) |
H1B | 0.5566 | 0.5596 | 0.8277 | 0.024 (4)* | 0.65 (2) |
C6A | 0.6807 (11) | 0.6816 (7) | 0.8775 (3) | 0.0221 (8) | 0.65 (2) |
C7A | 0.6877 (10) | 0.6070 (7) | 0.9244 (3) | 0.0253 (7) | 0.65 (2) |
H7A | 0.6215 | 0.5361 | 0.9252 | 0.038* | 0.65 (2) |
C8A | 0.7917 (10) | 0.6362 (8) | 0.9700 (2) | 0.0301 (11) | 0.65 (2) |
H8A | 0.7965 | 0.5852 | 1.0021 | 0.045* | 0.65 (2) |
C9A | 0.8886 (7) | 0.7400 (9) | 0.9689 (3) | 0.0358 (15) | 0.65 (2) |
H9A | 0.9597 | 0.7599 | 1.0001 | 0.054* | 0.65 (2) |
C10A | 0.8816 (7) | 0.8146 (8) | 0.9220 (3) | 0.0374 (13) | 0.65 (2) |
H10A | 0.9478 | 0.8855 | 0.9212 | 0.056* | 0.65 (2) |
C11A | 0.7776 (10) | 0.7854 (7) | 0.8763 (2) | 0.0302 (10) | 0.65 (2) |
H11A | 0.7728 | 0.8363 | 0.8443 | 0.045* | 0.65 (2) |
H1C | 0.5581 | 0.5603 | 0.8328 | 0.024 (4)* | 0.35 (2) |
H1D | 0.6299 | 0.6604 | 0.7910 | 0.024 (4)* | 0.35 (2) |
C6B | 0.674 (2) | 0.6987 (12) | 0.8754 (5) | 0.0221 (8) | 0.35 (2) |
C7B | 0.701 (2) | 0.6276 (11) | 0.9227 (6) | 0.0253 (7) | 0.35 (2) |
H7B | 0.6432 | 0.5536 | 0.9262 | 0.038* | 0.35 (2) |
C8B | 0.8129 (17) | 0.6648 (11) | 0.9650 (4) | 0.0301 (11) | 0.35 (2) |
H8B | 0.8313 | 0.6162 | 0.9973 | 0.045* | 0.35 (2) |
C9B | 0.8977 (14) | 0.7731 (10) | 0.9599 (5) | 0.0358 (15) | 0.35 (2) |
H9B | 0.9741 | 0.7985 | 0.9888 | 0.054* | 0.35 (2) |
C10B | 0.8707 (15) | 0.8442 (8) | 0.9126 (5) | 0.0374 (13) | 0.35 (2) |
H10B | 0.9287 | 0.9182 | 0.9091 | 0.056* | 0.35 (2) |
C11B | 0.759 (2) | 0.8070 (10) | 0.8704 (4) | 0.0302 (10) | 0.35 (2) |
H11B | 0.7406 | 0.8556 | 0.8380 | 0.045* | 0.35 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Si1 | 0.0231 (2) | 0.0236 (2) | 0.0223 (2) | −0.0014 (2) | 0.00206 (19) | −0.00087 (18) |
O1 | 0.0239 (6) | 0.0230 (6) | 0.0232 (6) | 0.0044 (5) | 0.0025 (5) | 0.0000 (5) |
O2 | 0.0286 (8) | 0.0666 (12) | 0.0426 (9) | 0.0010 (8) | −0.0066 (7) | −0.0208 (8) |
N1 | 0.0277 (8) | 0.0224 (7) | 0.0220 (7) | 0.0041 (6) | 0.0020 (6) | 0.0020 (5) |
C1 | 0.0258 (8) | 0.0242 (8) | 0.0257 (9) | 0.0026 (8) | 0.0028 (7) | −0.0013 (7) |
C2 | 0.0252 (9) | 0.0239 (8) | 0.0216 (8) | 0.0039 (7) | 0.0024 (7) | −0.0030 (6) |
C3 | 0.0218 (9) | 0.0243 (8) | 0.0220 (8) | 0.0050 (7) | −0.0005 (7) | −0.0018 (6) |
C4 | 0.0291 (9) | 0.0321 (10) | 0.0240 (9) | 0.0099 (8) | −0.0049 (8) | −0.0018 (7) |
C5 | 0.0360 (10) | 0.0338 (9) | 0.0192 (8) | 0.0076 (10) | −0.0018 (8) | 0.0006 (7) |
C12 | 0.0305 (11) | 0.0463 (12) | 0.0255 (10) | 0.0110 (9) | −0.0075 (8) | −0.0091 (8) |
C13 | 0.0550 (14) | 0.0336 (10) | 0.0229 (9) | −0.0006 (10) | 0.0048 (9) | −0.0018 (8) |
C15 | 0.0326 (10) | 0.0224 (8) | 0.0263 (9) | 0.0005 (8) | 0.0018 (8) | 0.0005 (6) |
C16 | 0.0640 (16) | 0.0326 (10) | 0.0317 (11) | 0.0026 (11) | −0.0004 (11) | −0.0092 (8) |
C18 | 0.0639 (16) | 0.0252 (9) | 0.0396 (11) | 0.0021 (11) | 0.0088 (11) | 0.0062 (8) |
C14 | 0.0237 (10) | 0.0519 (14) | 0.0559 (15) | −0.0060 (9) | 0.0065 (10) | 0.0070 (11) |
C17 | 0.0284 (10) | 0.0384 (12) | 0.0641 (16) | 0.0096 (9) | 0.0005 (10) | 0.0018 (11) |
B1 | 0.0468 (14) | 0.0231 (11) | 0.0423 (14) | 0.0071 (10) | 0.0013 (11) | 0.0085 (9) |
C6A | 0.0217 (10) | 0.016 (2) | 0.0291 (10) | 0.0048 (15) | 0.0036 (8) | −0.0030 (11) |
C7A | 0.0224 (15) | 0.023 (2) | 0.0305 (10) | −0.0029 (14) | 0.0028 (10) | −0.0003 (14) |
C8A | 0.021 (2) | 0.041 (3) | 0.0286 (14) | −0.003 (2) | 0.0035 (13) | 0.0010 (16) |
C9A | 0.0274 (13) | 0.040 (4) | 0.040 (2) | −0.004 (2) | 0.0009 (16) | −0.015 (2) |
C10A | 0.0344 (14) | 0.016 (3) | 0.062 (3) | 0.0001 (19) | −0.0003 (15) | −0.011 (2) |
C11A | 0.027 (2) | 0.015 (2) | 0.0487 (16) | 0.0066 (18) | 0.0001 (12) | 0.0038 (14) |
C6B | 0.0217 (10) | 0.016 (2) | 0.0291 (10) | 0.0048 (15) | 0.0036 (8) | −0.0030 (11) |
C7B | 0.0224 (15) | 0.023 (2) | 0.0305 (10) | −0.0029 (14) | 0.0028 (10) | −0.0003 (14) |
C8B | 0.021 (2) | 0.041 (3) | 0.0286 (14) | −0.003 (2) | 0.0035 (13) | 0.0010 (16) |
C9B | 0.0274 (13) | 0.040 (4) | 0.040 (2) | −0.004 (2) | 0.0009 (16) | −0.015 (2) |
C10B | 0.0344 (14) | 0.016 (3) | 0.062 (3) | 0.0001 (19) | −0.0003 (15) | −0.011 (2) |
C11B | 0.027 (2) | 0.015 (2) | 0.0487 (16) | 0.0066 (18) | 0.0001 (12) | 0.0038 (14) |
Si1—O1 | 1.6613 (14) | C16—H16B | 0.9800 |
Si1—C14 | 1.860 (2) | C16—H16C | 0.9800 |
Si1—C13 | 1.870 (2) | C18—H18A | 0.9800 |
Si1—C15 | 1.881 (2) | C18—H18B | 0.9800 |
O1—C3 | 1.426 (2) | C18—H18C | 0.9800 |
O2—C12 | 1.417 (3) | C14—H14A | 0.9800 |
O2—H2 | 0.89 (4) | C14—H14B | 0.9800 |
N1—C1 | 1.515 (2) | C14—H14C | 0.9800 |
N1—C2 | 1.520 (2) | C17—H17A | 0.9800 |
N1—C5 | 1.523 (2) | C17—H17B | 0.9800 |
N1—B1 | 1.627 (3) | C17—H17C | 0.9800 |
C1—C6B | 1.519 (4) | B1—H1B1 | 1.21 (3) |
C1—C6A | 1.524 (3) | B1—H2B1 | 1.10 (2) |
C1—H1A | 0.9892 (19) | B1—H3B1 | 1.17 (2) |
C1—H1B | 0.9901 (19) | C6A—C7A | 1.3900 |
C1—H1C | 0.9901 (19) | C6A—C11A | 1.3900 |
C1—H1D | 0.9892 (18) | C7A—C8A | 1.3900 |
C2—C3 | 1.517 (3) | C7A—H7A | 0.9500 |
C2—H2A | 0.9900 | C8A—C9A | 1.3900 |
C2—H2B | 0.9900 | C8A—H8A | 0.9500 |
C3—C4 | 1.538 (2) | C9A—C10A | 1.3900 |
C3—H3 | 1.0000 | C9A—H9A | 0.9500 |
C4—C12 | 1.514 (3) | C10A—C11A | 1.3900 |
C4—C5 | 1.522 (3) | C10A—H10A | 0.9500 |
C4—H4 | 1.0000 | C11A—H11A | 0.9500 |
C5—H5A | 0.9900 | C6B—C7B | 1.3900 |
C5—H5B | 0.9900 | C6B—C11B | 1.3900 |
C12—H12A | 0.9900 | C7B—C8B | 1.3900 |
C12—H12B | 0.9900 | C7B—H7B | 0.9500 |
C13—H13A | 0.9800 | C8B—C9B | 1.3900 |
C13—H13B | 0.9800 | C8B—H8B | 0.9500 |
C13—H13C | 0.9800 | C9B—C10B | 1.3900 |
C15—C16 | 1.529 (3) | C9B—H9B | 0.9500 |
C15—C17 | 1.534 (3) | C10B—C11B | 1.3900 |
C15—C18 | 1.539 (3) | C10B—H10B | 0.9500 |
C16—H16A | 0.9800 | C11B—H11B | 0.9500 |
O1—Si1—C14 | 109.93 (10) | C4—C12—H12A | 110.2 |
O1—Si1—C13 | 109.19 (9) | O2—C12—H12B | 110.2 |
C14—Si1—C13 | 109.55 (12) | C4—C12—H12B | 110.2 |
O1—Si1—C15 | 104.45 (8) | H12A—C12—H12B | 108.5 |
C14—Si1—C15 | 111.29 (11) | Si1—C13—H13A | 109.5 |
C13—Si1—C15 | 112.30 (10) | Si1—C13—H13B | 109.5 |
C3—O1—Si1 | 121.94 (11) | H13A—C13—H13B | 109.5 |
C12—O2—H2 | 109 (2) | Si1—C13—H13C | 109.5 |
C1—N1—C2 | 111.83 (14) | H13A—C13—H13C | 109.5 |
C1—N1—C5 | 107.21 (14) | H13B—C13—H13C | 109.5 |
C2—N1—C5 | 105.48 (14) | C16—C15—C17 | 108.5 (2) |
C1—N1—B1 | 113.00 (17) | C16—C15—C18 | 109.68 (17) |
C2—N1—B1 | 108.86 (15) | C17—C15—C18 | 108.65 (19) |
C5—N1—B1 | 110.18 (15) | C16—C15—Si1 | 109.76 (15) |
N1—C1—C6B | 113.1 (7) | C17—C15—Si1 | 110.63 (14) |
N1—C1—C6A | 118.3 (4) | C18—C15—Si1 | 109.62 (14) |
N1—C1—H1A | 107.85 (16) | C15—C16—H16A | 109.5 |
C6A—C1—H1A | 107.8 (4) | C15—C16—H16B | 109.5 |
N1—C1—H1B | 107.82 (16) | H16A—C16—H16B | 109.5 |
C6B—C1—H1B | 115.0 (6) | C15—C16—H16C | 109.5 |
H1A—C1—H1B | 107.24 (17) | H16A—C16—H16C | 109.5 |
N1—C1—H1C | 108.75 (16) | H16B—C16—H16C | 109.5 |
C6B—C1—H1C | 108.8 (5) | C15—C18—H18A | 109.5 |
N1—C1—H1D | 108.79 (16) | C15—C18—H18B | 109.5 |
C6B—C1—H1D | 109.6 (7) | H18A—C18—H18B | 109.5 |
H1C—C1—H1D | 107.73 (17) | C15—C18—H18C | 109.5 |
C3—C2—N1 | 106.47 (14) | H18A—C18—H18C | 109.5 |
C3—C2—H2A | 110.4 | H18B—C18—H18C | 109.5 |
N1—C2—H2A | 110.4 | Si1—C14—H14A | 109.5 |
C3—C2—H2B | 110.4 | Si1—C14—H14B | 109.5 |
N1—C2—H2B | 110.4 | H14A—C14—H14B | 109.5 |
H2A—C2—H2B | 108.6 | Si1—C14—H14C | 109.5 |
O1—C3—C2 | 109.84 (14) | H14A—C14—H14C | 109.5 |
O1—C3—C4 | 109.51 (14) | H14B—C14—H14C | 109.5 |
C2—C3—C4 | 102.15 (15) | C15—C17—H17A | 109.5 |
O1—C3—H3 | 111.6 | C15—C17—H17B | 109.5 |
C2—C3—H3 | 111.6 | H17A—C17—H17B | 109.5 |
C4—C3—H3 | 111.6 | C15—C17—H17C | 109.5 |
C12—C4—C5 | 113.23 (17) | H17A—C17—H17C | 109.5 |
C12—C4—C3 | 114.49 (17) | H17B—C17—H17C | 109.5 |
C5—C4—C3 | 102.00 (15) | N1—B1—H1B1 | 102.0 (13) |
C12—C4—H4 | 108.9 | N1—B1—H2B1 | 108.5 (13) |
C5—C4—H4 | 108.9 | H1B1—B1—H2B1 | 115.5 (18) |
C3—C4—H4 | 108.9 | N1—B1—H3B1 | 107.0 (13) |
C4—C5—N1 | 105.97 (15) | H1B1—B1—H3B1 | 112.3 (18) |
C4—C5—H5A | 110.5 | H2B1—B1—H3B1 | 110.7 (17) |
N1—C5—H5A | 110.5 | C7A—C6A—C11A | 120.0 |
C4—C5—H5B | 110.5 | C7A—C6A—C1 | 119.5 (4) |
N1—C5—H5B | 110.5 | C11A—C6A—C1 | 120.5 (4) |
H5A—C5—H5B | 108.7 | C7B—C6B—C1 | 117.9 (9) |
O2—C12—C4 | 107.69 (17) | C11B—C6B—C1 | 121.7 (9) |
O2—C12—H12A | 110.2 | C8B—C7B—C6B | 120.0 |
C14—Si1—O1—C3 | 58.17 (16) | B1—N1—C5—C4 | −102.89 (18) |
C13—Si1—O1—C3 | −62.04 (16) | C5—C4—C12—O2 | −177.24 (17) |
C15—Si1—O1—C3 | 177.66 (13) | C3—C4—C12—O2 | 66.4 (2) |
C2—N1—C1—C6B | −65.1 (7) | O1—Si1—C15—C16 | −58.17 (17) |
C5—N1—C1—C6B | 179.8 (7) | C14—Si1—C15—C16 | 60.40 (19) |
B1—N1—C1—C6B | 58.2 (7) | C13—Si1—C15—C16 | −176.37 (15) |
C2—N1—C1—C6A | −58.7 (4) | O1—Si1—C15—C17 | 61.49 (17) |
C5—N1—C1—C6A | −173.9 (4) | C14—Si1—C15—C17 | −179.94 (17) |
B1—N1—C1—C6A | 64.5 (4) | C13—Si1—C15—C17 | −56.71 (18) |
C1—N1—C2—C3 | −103.77 (16) | O1—Si1—C15—C18 | −178.71 (15) |
C5—N1—C2—C3 | 12.44 (18) | C14—Si1—C15—C18 | −60.14 (18) |
B1—N1—C2—C3 | 130.66 (17) | C13—Si1—C15—C18 | 63.09 (18) |
Si1—O1—C3—C2 | 108.11 (15) | N1—C1—C6A—C7A | 97.2 (4) |
Si1—O1—C3—C4 | −140.46 (14) | C6B—C1—C6A—C7A | 146 (9) |
N1—C2—C3—O1 | 82.14 (17) | N1—C1—C6A—C11A | −84.2 (6) |
N1—C2—C3—C4 | −34.03 (17) | C6B—C1—C6A—C11A | −35 (8) |
O1—C3—C4—C12 | 48.4 (2) | C1—C6A—C7A—C8A | 178.7 (7) |
C2—C3—C4—C12 | 164.83 (16) | C1—C6A—C11A—C10A | −178.7 (7) |
O1—C3—C4—C5 | −74.25 (18) | N1—C1—C6B—C7B | 107.0 (7) |
C2—C3—C4—C5 | 42.16 (17) | C6A—C1—C6B—C7B | −27 (8) |
C12—C4—C5—N1 | −158.73 (16) | N1—C1—C6B—C11B | −80.9 (11) |
C3—C4—C5—N1 | −35.20 (18) | C6A—C1—C6B—C11B | 146 (9) |
C1—N1—C5—C4 | 133.77 (15) | C1—C6B—C7B—C8B | 172.3 (15) |
C2—N1—C5—C4 | 14.45 (18) | C1—C6B—C11B—C10B | −172.0 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···H1B1i | 0.89 (3) | 1.76 (4) | 2.62 (2) | 162 (3) |
C3—H3···Cg1ii | 1.00 | 2.78 | 3.662 (3) | 147 |
Symmetry codes: (i) −x, y−1/2, −z+3/2; (ii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C18H34BNO2Si |
Mr | 335.36 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 113 |
a, b, c (Å) | 7.8078 (7), 11.2328 (10), 23.639 (2) |
V (Å3) | 2073.2 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.65 × 0.60 × 0.30 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | Multi-scan (Blessing, 1995) |
Tmin, Tmax | 0.418, 0.746 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 42018, 4901, 4409 |
Rint | 0.089 |
(sin θ/λ)max (Å−1) | 0.660 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.134, 1.07 |
No. of reflections | 4901 |
No. of parameters | 225 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.63, −0.44 |
Absolute structure | Flack (1983), 2102 Friedel pairs |
Absolute structure parameter | 0.07 (13) |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SAINT and SADABS (Bruker, 2005), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997); PLATON (Spek, 2009), SHELXL97 (Sheldrick, 2008); PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···H1B1i | 0.89 (3) | 1.76 (4) | 2.62 (2) | 162 (3) |
C3—H3···Cg1ii | 1.00 | 2.78 | 3.662 (3) | 147 |
Symmetry codes: (i) −x, y−1/2, −z+3/2; (ii) x−1, y, z. |
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During the course of our efforts to synthesize the two pairs of enantiomeric 3-O-TBDMS-protected [TBDMS = tert-butyldimethylsilyl?] 1-benzyl-3-hydroxy-4-(hydroxymethyl)pyrrolidine scaffolds by reduction of the corresponding enantiomeric pairs of lactam esters (Clinch et al., 2007) with BH3.SMe2, we recovered, unexpectedly, only the borane-complexed pyrrolidine derivatives as stable, low melting, waxy solids. From the reduction of the (+)-cis lactam ester (see Scheme), we were able to isolate the corresponding borane-complexed pyrrolidine title compound, (I), as large, colourless crystals. As a result of this particular reaction, only a single compound was isolated as was evinced from the appearance of a single resonance in the 11B NMR spectrum and the appearance of a single peak in the chiral-phase HPLC [HPLC = high-performance liquid chromatography?] chromatogram. In contrast, the borane complexes isolated from the reductions of the trans-lactams were also isolated as chromatographically homogeneous compounds but were shown to be diastereoisomeric, presumably as a result of the capture of each of the pyrrolidino `invertomers'. In the 1H and 11B NMR spectra and in chiral-phase HPLC chromatograms, the ratios of the diastereoisomers were essentially consistent (at ~2:1).
The crystal structure of the title (-)-cis borane complex is interesting in that, in binding the borane residue from the less-hindered face, the N-benzyl group is forced into a configuration syn to the substituents at C3 and C4. A similar phenomenon has been observed in the formation of the borane complex (adduct) with (S)-N-benzylproline methyl ester (Ferey et al., 1996). Here the N-boronato group and the carboxylate functionality at C2 are cis to each other, a configuration that relieves any potentially unfavourable interaction with the benzyl group.
The asymmetric unit of the title compound, (I), contains one independent [(1R,3R,4S)-1-benzyl-3-(tert-butyldimethylsilyloxy)-4-(hydroxymethyl) pyrrolidinium-1-yl] trihydroborate molecule (Fig. 1). As shown in Fig. 1, the phenyl ring (C6–C11) is conformationally disordered in two orientations [in the ratio a:b of 0.65 (2):0.35 (2)]; the rings were refined as rigid bodies (C—C 1.390 Å). The data would not support refinement of two independent sites for atom C1. The pyrrolidine ring adopts a twist ring conformation on C3—C4 with Q(2) 0.414 (2) Å and ϕ 271.5 (3)° (Cremer & Pople, 1975). The absolute configurations are confirmed to be N1(R), C3(R) and C4(S) as expected from the synthesis, with the Hooft y parameter 0.11 (6) (Hooft et al., 2009).
Lattice binding is provided by unusual B—H···H—O hydrogen bonds (Table 1, Fig. 2), in which the borane H atoms act as acceptors, generating what would be a C(8) binding motif (Bernstein et al., 1995). This combination of hydroxyl proton donors and borane H acceptors is rarely observed: the one example located has two bifurcated O—H (weaker) interactions to both borane H atoms in ABUKAJ (Blakemore et al., 2001) generating two C(7) motifs. This interaction does not appear to have affected the molecular bonding significantly with a B—N bond length of 1.625 (3) Å compared with 1.637 and 1.633 Å in related compounds TUSSOP (Ferey et al., 1996) and TUHJEL (Lam et al., 2002). We have previously noted the related (nitrogen equivalent) B—H···H—N strong lattice binding in amine-boranes (e.g. SOYTOQ, Gainsford & Bowden, 2009). A weak C—H···π interaction is also present (in Table 1, Cg1 is the centre of the C6A–C10A phenyl ring), which has not prevented the observed conformational disorder in the ring. [ABUKAJ, TUSSOP, TUHJEL, SOYTOQ - are these Cambridge Structural Database refcodes?]