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The absolute configuration of the title cis-(1R,3R,4S)-pyrrolidine–borane complex, C18H34BNO2Si, was confirmed. Together with the related trans isomers (3S,4S) and (3R,4R), it was obtained unexpectedly from the BH3·SMe2 reduction of the corresponding chiral (3R,4R)-lactam precursor. The phenyl ring is disordered over two conformations in the ratio 0.65:0.35. The crystallographic packing is dominated by the rarely found donor–acceptor hy­droxy–borane O—H...H—B hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270110026879/gd3351sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270110026879/gd3351Isup2.hkl
Contains datablock I

CCDC reference: 790649

Comment top

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?]

Related literature top

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).

Experimental top

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.

Refinement top

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).

Computing details top

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).

Figures top
[Figure 1] Fig. 1. The asymmetric unit contents of (I) (Farrugia, 1997) with all atoms at the 30% thermal ellipsoid level. The two phenyl group orientations [labelled as a and b sets with occupancies 0.65 (2) and 0.35 (2), respectively] are distinguished by full and dashed bonds. For the sake of clarity, only one set of H atoms on atom C1 is shown (see text).
[Figure 2] Fig. 2. A Mercury packing view (Macrae et al., 2008) of the cell highlighting the unusual B—H···H—O major hydrogen bond (dotted). Only selected H atoms involved in packing are shown in ball mode (see Table 1). Symmetry codes: (i) -x, 1/2 + y, 3/2 - z (ii) 1/2 - x, 1 - y, z - 1/2 (iii) 3/2 - x, 1 - y, z - 1/2.
[(1R,3R,4S)-1-Benzyl-3-(tert- butyldimethylsilyloxy)-4-(hydroxymethyl)pyrrolidine–borane top
Crystal data top
C18H34BNO2SiF(000) = 736
Mr = 335.36Dx = 1.074 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 9852 reflections
a = 7.8078 (7) Åθ = 3.1–27.5°
b = 11.2328 (10) ŵ = 0.12 mm1
c = 23.639 (2) ÅT = 113 K
V = 2073.2 (3) Å3Block, colourless
Z = 40.65 × 0.60 × 0.30 mm
Data collection top
Bruker APEXII CCD
diffractometer
4901 independent reflections
Radiation source: fine-focus sealed tube4409 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.089
Detector resolution: 8.333 pixels mm-1θmax = 28.0°, θmin = 2.5°
ϕ and ω scansh = 1010
Absorption correction: multi-scan
(Blessing, 1995)
k = 1414
Tmin = 0.418, Tmax = 0.746l = 3031
42018 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH 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 = 1.07Δρmax = 0.63 e Å3
4901 reflectionsΔρmin = 0.44 e Å3
225 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.014 (2)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 2102 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.07 (13)
Crystal data top
C18H34BNO2SiV = 2073.2 (3) Å3
Mr = 335.36Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.8078 (7) ŵ = 0.12 mm1
b = 11.2328 (10) ÅT = 113 K
c = 23.639 (2) Å0.65 × 0.60 × 0.30 mm
Data collection top
Bruker APEXII CCD
diffractometer
4901 independent reflections
Absorption correction: multi-scan
(Blessing, 1995)
4409 reflections with I > 2σ(I)
Tmin = 0.418, Tmax = 0.746Rint = 0.089
42018 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.049H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.134Δρmax = 0.63 e Å3
S = 1.07Δρmin = 0.44 e Å3
4901 reflectionsAbsolute structure: Flack (1983), 2102 Friedel pairs
225 parametersAbsolute structure parameter: 0.07 (13)
1 restraint
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Si10.19313 (6)0.36108 (4)0.90701 (2)0.02300 (14)
O10.24122 (17)0.46153 (11)0.85794 (5)0.0234 (3)
O20.1258 (2)0.49256 (18)0.78076 (8)0.0459 (4)
H20.186 (4)0.448 (3)0.7566 (14)0.069*
N10.3916 (2)0.70105 (14)0.82291 (6)0.0240 (3)
C10.5692 (2)0.64733 (17)0.82715 (8)0.0252 (4)
C20.2826 (2)0.67121 (16)0.87428 (7)0.0236 (4)
H2A0.35550.64240.90570.028*
H2B0.21920.74250.88730.028*
C30.1588 (2)0.57473 (16)0.85575 (7)0.0227 (4)
H30.05140.57570.87880.027*
C40.1243 (3)0.60854 (18)0.79376 (8)0.0284 (4)
H40.04970.68090.79280.034*
C50.3025 (3)0.64194 (18)0.77299 (8)0.0297 (4)
H5A0.29500.69760.74060.036*
H5B0.36610.57010.76090.036*
C120.0412 (3)0.5112 (2)0.75898 (9)0.0341 (5)
H12A0.03500.53540.71880.041*
H12B0.10900.43700.76160.041*
C130.2448 (3)0.42308 (19)0.97843 (8)0.0371 (5)
H13A0.18480.49890.98360.056*
H13B0.36860.43610.98140.056*
H13C0.20810.36671.00770.056*
C150.3296 (3)0.22853 (16)0.88877 (8)0.0271 (4)
C160.2894 (4)0.1871 (2)0.82863 (10)0.0428 (6)
H16A0.36110.11820.81930.064*
H16B0.31300.25190.80200.064*
H16C0.16840.16460.82610.064*
C180.2936 (4)0.12692 (18)0.93078 (10)0.0429 (6)
H18A0.36010.05650.91990.064*
H18B0.17120.10760.93020.064*
H18C0.32660.15200.96900.064*
C140.0388 (3)0.3239 (2)0.90344 (12)0.0438 (6)
H14A0.07130.30900.86400.066*
H14B0.10600.39050.91830.066*
H14C0.06130.25250.92610.066*
C170.5203 (3)0.2607 (2)0.89198 (12)0.0436 (6)
H17A0.54530.32450.86490.065*
H17B0.58930.19040.88270.065*
H17C0.54810.28760.93030.065*
B10.3945 (4)0.8448 (2)0.81456 (11)0.0374 (6)
H1B10.246 (3)0.866 (2)0.8036 (11)0.045 (7)*
H2B10.444 (3)0.886 (2)0.8538 (10)0.030 (6)*
H3B10.485 (3)0.865 (2)0.7766 (10)0.033 (6)*
H1A0.63240.66830.79230.024 (4)*0.65 (2)
H1B0.55660.55960.82770.024 (4)*0.65 (2)
C6A0.6807 (11)0.6816 (7)0.8775 (3)0.0221 (8)0.65 (2)
C7A0.6877 (10)0.6070 (7)0.9244 (3)0.0253 (7)0.65 (2)
H7A0.62150.53610.92520.038*0.65 (2)
C8A0.7917 (10)0.6362 (8)0.9700 (2)0.0301 (11)0.65 (2)
H8A0.79650.58521.00210.045*0.65 (2)
C9A0.8886 (7)0.7400 (9)0.9689 (3)0.0358 (15)0.65 (2)
H9A0.95970.75991.00010.054*0.65 (2)
C10A0.8816 (7)0.8146 (8)0.9220 (3)0.0374 (13)0.65 (2)
H10A0.94780.88550.92120.056*0.65 (2)
C11A0.7776 (10)0.7854 (7)0.8763 (2)0.0302 (10)0.65 (2)
H11A0.77280.83630.84430.045*0.65 (2)
H1C0.55810.56030.83280.024 (4)*0.35 (2)
H1D0.62990.66040.79100.024 (4)*0.35 (2)
C6B0.674 (2)0.6987 (12)0.8754 (5)0.0221 (8)0.35 (2)
C7B0.701 (2)0.6276 (11)0.9227 (6)0.0253 (7)0.35 (2)
H7B0.64320.55360.92620.038*0.35 (2)
C8B0.8129 (17)0.6648 (11)0.9650 (4)0.0301 (11)0.35 (2)
H8B0.83130.61620.99730.045*0.35 (2)
C9B0.8977 (14)0.7731 (10)0.9599 (5)0.0358 (15)0.35 (2)
H9B0.97410.79850.98880.054*0.35 (2)
C10B0.8707 (15)0.8442 (8)0.9126 (5)0.0374 (13)0.35 (2)
H10B0.92870.91820.90910.056*0.35 (2)
C11B0.759 (2)0.8070 (10)0.8704 (4)0.0302 (10)0.35 (2)
H11B0.74060.85560.83800.045*0.35 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.0231 (2)0.0236 (2)0.0223 (2)0.0014 (2)0.00206 (19)0.00087 (18)
O10.0239 (6)0.0230 (6)0.0232 (6)0.0044 (5)0.0025 (5)0.0000 (5)
O20.0286 (8)0.0666 (12)0.0426 (9)0.0010 (8)0.0066 (7)0.0208 (8)
N10.0277 (8)0.0224 (7)0.0220 (7)0.0041 (6)0.0020 (6)0.0020 (5)
C10.0258 (8)0.0242 (8)0.0257 (9)0.0026 (8)0.0028 (7)0.0013 (7)
C20.0252 (9)0.0239 (8)0.0216 (8)0.0039 (7)0.0024 (7)0.0030 (6)
C30.0218 (9)0.0243 (8)0.0220 (8)0.0050 (7)0.0005 (7)0.0018 (6)
C40.0291 (9)0.0321 (10)0.0240 (9)0.0099 (8)0.0049 (8)0.0018 (7)
C50.0360 (10)0.0338 (9)0.0192 (8)0.0076 (10)0.0018 (8)0.0006 (7)
C120.0305 (11)0.0463 (12)0.0255 (10)0.0110 (9)0.0075 (8)0.0091 (8)
C130.0550 (14)0.0336 (10)0.0229 (9)0.0006 (10)0.0048 (9)0.0018 (8)
C150.0326 (10)0.0224 (8)0.0263 (9)0.0005 (8)0.0018 (8)0.0005 (6)
C160.0640 (16)0.0326 (10)0.0317 (11)0.0026 (11)0.0004 (11)0.0092 (8)
C180.0639 (16)0.0252 (9)0.0396 (11)0.0021 (11)0.0088 (11)0.0062 (8)
C140.0237 (10)0.0519 (14)0.0559 (15)0.0060 (9)0.0065 (10)0.0070 (11)
C170.0284 (10)0.0384 (12)0.0641 (16)0.0096 (9)0.0005 (10)0.0018 (11)
B10.0468 (14)0.0231 (11)0.0423 (14)0.0071 (10)0.0013 (11)0.0085 (9)
C6A0.0217 (10)0.016 (2)0.0291 (10)0.0048 (15)0.0036 (8)0.0030 (11)
C7A0.0224 (15)0.023 (2)0.0305 (10)0.0029 (14)0.0028 (10)0.0003 (14)
C8A0.021 (2)0.041 (3)0.0286 (14)0.003 (2)0.0035 (13)0.0010 (16)
C9A0.0274 (13)0.040 (4)0.040 (2)0.004 (2)0.0009 (16)0.015 (2)
C10A0.0344 (14)0.016 (3)0.062 (3)0.0001 (19)0.0003 (15)0.011 (2)
C11A0.027 (2)0.015 (2)0.0487 (16)0.0066 (18)0.0001 (12)0.0038 (14)
C6B0.0217 (10)0.016 (2)0.0291 (10)0.0048 (15)0.0036 (8)0.0030 (11)
C7B0.0224 (15)0.023 (2)0.0305 (10)0.0029 (14)0.0028 (10)0.0003 (14)
C8B0.021 (2)0.041 (3)0.0286 (14)0.003 (2)0.0035 (13)0.0010 (16)
C9B0.0274 (13)0.040 (4)0.040 (2)0.004 (2)0.0009 (16)0.015 (2)
C10B0.0344 (14)0.016 (3)0.062 (3)0.0001 (19)0.0003 (15)0.011 (2)
C11B0.027 (2)0.015 (2)0.0487 (16)0.0066 (18)0.0001 (12)0.0038 (14)
Geometric parameters (Å, º) top
Si1—O11.6613 (14)C16—H16B0.9800
Si1—C141.860 (2)C16—H16C0.9800
Si1—C131.870 (2)C18—H18A0.9800
Si1—C151.881 (2)C18—H18B0.9800
O1—C31.426 (2)C18—H18C0.9800
O2—C121.417 (3)C14—H14A0.9800
O2—H20.89 (4)C14—H14B0.9800
N1—C11.515 (2)C14—H14C0.9800
N1—C21.520 (2)C17—H17A0.9800
N1—C51.523 (2)C17—H17B0.9800
N1—B11.627 (3)C17—H17C0.9800
C1—C6B1.519 (4)B1—H1B11.21 (3)
C1—C6A1.524 (3)B1—H2B11.10 (2)
C1—H1A0.9892 (19)B1—H3B11.17 (2)
C1—H1B0.9901 (19)C6A—C7A1.3900
C1—H1C0.9901 (19)C6A—C11A1.3900
C1—H1D0.9892 (18)C7A—C8A1.3900
C2—C31.517 (3)C7A—H7A0.9500
C2—H2A0.9900C8A—C9A1.3900
C2—H2B0.9900C8A—H8A0.9500
C3—C41.538 (2)C9A—C10A1.3900
C3—H31.0000C9A—H9A0.9500
C4—C121.514 (3)C10A—C11A1.3900
C4—C51.522 (3)C10A—H10A0.9500
C4—H41.0000C11A—H11A0.9500
C5—H5A0.9900C6B—C7B1.3900
C5—H5B0.9900C6B—C11B1.3900
C12—H12A0.9900C7B—C8B1.3900
C12—H12B0.9900C7B—H7B0.9500
C13—H13A0.9800C8B—C9B1.3900
C13—H13B0.9800C8B—H8B0.9500
C13—H13C0.9800C9B—C10B1.3900
C15—C161.529 (3)C9B—H9B0.9500
C15—C171.534 (3)C10B—C11B1.3900
C15—C181.539 (3)C10B—H10B0.9500
C16—H16A0.9800C11B—H11B0.9500
O1—Si1—C14109.93 (10)C4—C12—H12A110.2
O1—Si1—C13109.19 (9)O2—C12—H12B110.2
C14—Si1—C13109.55 (12)C4—C12—H12B110.2
O1—Si1—C15104.45 (8)H12A—C12—H12B108.5
C14—Si1—C15111.29 (11)Si1—C13—H13A109.5
C13—Si1—C15112.30 (10)Si1—C13—H13B109.5
C3—O1—Si1121.94 (11)H13A—C13—H13B109.5
C12—O2—H2109 (2)Si1—C13—H13C109.5
C1—N1—C2111.83 (14)H13A—C13—H13C109.5
C1—N1—C5107.21 (14)H13B—C13—H13C109.5
C2—N1—C5105.48 (14)C16—C15—C17108.5 (2)
C1—N1—B1113.00 (17)C16—C15—C18109.68 (17)
C2—N1—B1108.86 (15)C17—C15—C18108.65 (19)
C5—N1—B1110.18 (15)C16—C15—Si1109.76 (15)
N1—C1—C6B113.1 (7)C17—C15—Si1110.63 (14)
N1—C1—C6A118.3 (4)C18—C15—Si1109.62 (14)
N1—C1—H1A107.85 (16)C15—C16—H16A109.5
C6A—C1—H1A107.8 (4)C15—C16—H16B109.5
N1—C1—H1B107.82 (16)H16A—C16—H16B109.5
C6B—C1—H1B115.0 (6)C15—C16—H16C109.5
H1A—C1—H1B107.24 (17)H16A—C16—H16C109.5
N1—C1—H1C108.75 (16)H16B—C16—H16C109.5
C6B—C1—H1C108.8 (5)C15—C18—H18A109.5
N1—C1—H1D108.79 (16)C15—C18—H18B109.5
C6B—C1—H1D109.6 (7)H18A—C18—H18B109.5
H1C—C1—H1D107.73 (17)C15—C18—H18C109.5
C3—C2—N1106.47 (14)H18A—C18—H18C109.5
C3—C2—H2A110.4H18B—C18—H18C109.5
N1—C2—H2A110.4Si1—C14—H14A109.5
C3—C2—H2B110.4Si1—C14—H14B109.5
N1—C2—H2B110.4H14A—C14—H14B109.5
H2A—C2—H2B108.6Si1—C14—H14C109.5
O1—C3—C2109.84 (14)H14A—C14—H14C109.5
O1—C3—C4109.51 (14)H14B—C14—H14C109.5
C2—C3—C4102.15 (15)C15—C17—H17A109.5
O1—C3—H3111.6C15—C17—H17B109.5
C2—C3—H3111.6H17A—C17—H17B109.5
C4—C3—H3111.6C15—C17—H17C109.5
C12—C4—C5113.23 (17)H17A—C17—H17C109.5
C12—C4—C3114.49 (17)H17B—C17—H17C109.5
C5—C4—C3102.00 (15)N1—B1—H1B1102.0 (13)
C12—C4—H4108.9N1—B1—H2B1108.5 (13)
C5—C4—H4108.9H1B1—B1—H2B1115.5 (18)
C3—C4—H4108.9N1—B1—H3B1107.0 (13)
C4—C5—N1105.97 (15)H1B1—B1—H3B1112.3 (18)
C4—C5—H5A110.5H2B1—B1—H3B1110.7 (17)
N1—C5—H5A110.5C7A—C6A—C11A120.0
C4—C5—H5B110.5C7A—C6A—C1119.5 (4)
N1—C5—H5B110.5C11A—C6A—C1120.5 (4)
H5A—C5—H5B108.7C7B—C6B—C1117.9 (9)
O2—C12—C4107.69 (17)C11B—C6B—C1121.7 (9)
O2—C12—H12A110.2C8B—C7B—C6B120.0
C14—Si1—O1—C358.17 (16)B1—N1—C5—C4102.89 (18)
C13—Si1—O1—C362.04 (16)C5—C4—C12—O2177.24 (17)
C15—Si1—O1—C3177.66 (13)C3—C4—C12—O266.4 (2)
C2—N1—C1—C6B65.1 (7)O1—Si1—C15—C1658.17 (17)
C5—N1—C1—C6B179.8 (7)C14—Si1—C15—C1660.40 (19)
B1—N1—C1—C6B58.2 (7)C13—Si1—C15—C16176.37 (15)
C2—N1—C1—C6A58.7 (4)O1—Si1—C15—C1761.49 (17)
C5—N1—C1—C6A173.9 (4)C14—Si1—C15—C17179.94 (17)
B1—N1—C1—C6A64.5 (4)C13—Si1—C15—C1756.71 (18)
C1—N1—C2—C3103.77 (16)O1—Si1—C15—C18178.71 (15)
C5—N1—C2—C312.44 (18)C14—Si1—C15—C1860.14 (18)
B1—N1—C2—C3130.66 (17)C13—Si1—C15—C1863.09 (18)
Si1—O1—C3—C2108.11 (15)N1—C1—C6A—C7A97.2 (4)
Si1—O1—C3—C4140.46 (14)C6B—C1—C6A—C7A146 (9)
N1—C2—C3—O182.14 (17)N1—C1—C6A—C11A84.2 (6)
N1—C2—C3—C434.03 (17)C6B—C1—C6A—C11A35 (8)
O1—C3—C4—C1248.4 (2)C1—C6A—C7A—C8A178.7 (7)
C2—C3—C4—C12164.83 (16)C1—C6A—C11A—C10A178.7 (7)
O1—C3—C4—C574.25 (18)N1—C1—C6B—C7B107.0 (7)
C2—C3—C4—C542.16 (17)C6A—C1—C6B—C7B27 (8)
C12—C4—C5—N1158.73 (16)N1—C1—C6B—C11B80.9 (11)
C3—C4—C5—N135.20 (18)C6A—C1—C6B—C11B146 (9)
C1—N1—C5—C4133.77 (15)C1—C6B—C7B—C8B172.3 (15)
C2—N1—C5—C414.45 (18)C1—C6B—C11B—C10B172.0 (15)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···H1B1i0.89 (3)1.76 (4)2.62 (2)162 (3)
C3—H3···Cg1ii1.002.783.662 (3)147
Symmetry codes: (i) x, y1/2, z+3/2; (ii) x1, y, z.

Experimental details

Crystal data
Chemical formulaC18H34BNO2Si
Mr335.36
Crystal system, space groupOrthorhombic, P212121
Temperature (K)113
a, b, c (Å)7.8078 (7), 11.2328 (10), 23.639 (2)
V3)2073.2 (3)
Z4
Radiation typeMo Kα
µ (mm1)0.12
Crystal size (mm)0.65 × 0.60 × 0.30
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(Blessing, 1995)
Tmin, Tmax0.418, 0.746
No. of measured, independent and
observed [I > 2σ(I)] reflections
42018, 4901, 4409
Rint0.089
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.049, 0.134, 1.07
No. of reflections4901
No. of parameters225
No. of restraints1
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.63, 0.44
Absolute structureFlack (1983), 2102 Friedel pairs
Absolute structure parameter0.07 (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).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···H1B1i0.89 (3)1.76 (4)2.62 (2)162 (3)
C3—H3···Cg1ii1.002.783.662 (3)147
Symmetry codes: (i) x, y1/2, z+3/2; (ii) x1, y, z.
 

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