J. Beckmann et al. / Journal of Organometallic Chemistry 648 (2002) 188–192
191
After cooling to room temperature (r.t.), the colorless
3.4. Synthesis of the trialkoxysilanols (MenO)3SiOH
(4) and (BorO)3SiOH (5)
precipitate of pyridinium chloride was filtered and the
solvent removed under reduced pressure. The residue
consists of pure product in 93 and 96% yield,
respectively.
At 0 °C a mixture of the trialkoxychlorosilane
((MenO)3SiCl: 10.6 g or (BorO)3SiCl: 10.5 g, 20.0
mmol) and pyridine (1.76 g, 22.0 mmol) in dry ether
was slowly added to a mixture of ether (30 ml) and
water (30 ml). After stirring at r.t. for 1 h, the layers
were separated, the organic phase was washed twice
with ice water (15 ml) and dried over Na2SO4. Ether
and the excess pyridine were removed in vacuum at
0 °C and for a short time at r.t. leaving pure products
in 94 and 95% yield, respectively.
3.2.1. (MenO)3SiCl (1), colorless oil
1H-NMR (CDCl3): l 3.76 (1H, td; H-1), 2.23 (1H, m;
H-7), 2.11 (1H, m; H-6), 1.60 (1H, m; H-3), 1.58 (1H,
m; H-4), 1.39 (1H, m; H-5), 1.22 (1H, m; H-2), 1.08
(1H, m; H-6%) 0.95 (1H, m; H-3), 0.90 (3H, d; H-8), 0.88
(3H, d; H-9), 0.84 (1H, m; H-4), 0.78 (3H, d; H-10).
13C-NMR (CDCl3): l 74.4 (C-1), 49.5 (C-2), 44.3 (C-6),
34.4 (C-4), 31.6 (C-5), 25.3 (C-7), 22.7 (C-3), 22.2 (C-8),
21.1 (C-9), 15.7 (C-10). 29Si-NMR (CDCl3): l −74.5.
Anal. Calc. for C30H57ClO3Si (529.32): C, 68.07; H,
10.85. Found: C, 68.15; H, 11.00%.
3.4.1. (MenO)3SiOH (4), colorless oil
1H-NMR (CDCl3): l 3.68 (1H, td; H-1), 2.24 (1H, m;
H-7), 2.14 (1H, m; H-6), 1.63 (1H, m; H-3), 1.57 (1H,
m; H-4), 1.37 (1H, m; H-5), 1.19 (1H, m; H-2), 1.08
(1H, m; H-6%) 1.05 (1H, m; H-3), 0.89 (3H, d; H-8), 0.87
(3H, d; H-9), 0.85 (1H, m; H-4), 0.76 (3H, d; H-10).
13C-NMR (CDCl3): l 73.3 (C-1), 49.6 (C-2), 44.7 (C-6),
34.5 (C-4), 31.7 (C-5), 25.1 (C-7), 22.6 (C-3), 22.2 (C-8),
21.2 (C-9), 15.6 (C-10). 29Si-NMR (CDCl3): l −82.2.
3.2.2. (BorO)3SiCl (2): colorless solid, m.p. 207 °C
1H-NMR (CDCl3): l 4.26 (1H, m; H-1), 2.23 (1H, m;
H-5), 2.00 (1H, m; H-6), 1.68 (1H, m; H-4), 1.62 (1H,
m; H-3), 1.21 (1H, m; H-4%), 1.12 (1H, m; H-3%), 1.06
(1H, dd; H-6%), 0.86, 0.85, 0.84 (9H, s; H-8, H-9, H-10).
13C-NMR (CDCl3): l 79.3 (C-1), 49.7 (C-2), 47.4 (C-7),
45.1 (C-5), 38.5 (C-6), 28.2 (C-3), 26.2 (C-4), 20.2 (C-8),
18.8 (C-9), 13.4 (C-10). 29Si-NMR (CDCl3): l −73.0.
Anal. Calc. for C30H51ClO3Si (523.27): C, 68.86; H,
9.82. Found: C, 68.85; H, 9.80%.
IR (Nujol): w(OH) 3410 cm−1
.
Anal. Calc. for C30H58O4Si (510.88): C, 70.53; H,
11.44. Found: C, 70.55; H, 11.50%.
3.4.2. (BorO)3SiOH (5), colorless solid, m.p. 227 °C
1H-NMR (CDCl3): l 4.24 (1H, m; H-1), 2.23 (1H, m;
H-5), 2.03 (1H, m; H-6), 1.68 (1H, m; H-4), 1.62 (1H,
m; H-3), 1.21 (1H, m; H-4%), 1.11 (1H, m; H-3%), 1.05
(1H, dd; H-6%), 0.86, 0.85, 0.84 (9H, s; H-8, H-9, H-10).
13C-NMR (CDCl3): l 78.2 (C-1), 49.6 (C-2), 47.4 (C-7),
45.1 (C-5), 38.8 (C-6), 28.3 (C-3), 26.2 (C-4), 20.2 (C-8),
18.8 (C-9), 13.5 (C-10). 29Si-NMR (CDCl3): l −79.8.
29Si MAS-NMR: l −78.2. IR (KBr): w(OH) 3380
3.3. Slow hydrolysis of (MenO)3SiCl (1) in the
presence of air moisture
A few grams of (MenO)3SiCl (1) were kept in a
loosely closed flask. After several weeks the original oil
had almost completely solidified and upon opening the
flask fumes of hydrogen chloride were noticed. Accord-
cm−1
.
Anal. Calc. for C30H52O4Si (504.83): C, 71.38; H,
10.38. Found: C, 71.30; H, 10.45%.
1
ing to H- and 13C-NMR spectra, the crude solidified
material consisted of (−)-menthol and (MenO)4Si (3)
from which the latter was isolated by recrystallization
from C6H6 in ca. 30% yield.
3.5. Crystal structure determinations
Intensity data for colorless crystals of 3 and 5 were
measured at 173 K on a Rigaku AFC7R diffractometer
employing Mo–Ka radiation and the ꢀ–2q scan tech-
nique such that qmax was 27.5°. Corrections were made
for Lorentz and polarization effects [27]. Crystallo-
graphic data are summarized in Table 1. The structures
were solved using heavy-atom methods for 3 [28] and
direct methods for 5 [29] and refined by a full-matrix
least-squares procedure based on F2 [30] with a weight-
ing scheme of the form w=1/[|2(Fo2)+(gP)2], where
P=(F2o+2F2c)/3. All non-hydrogen atoms were refined
with anisotropic displacement parameters and carbon-
bound hydrogen atoms were included in the models in
their idealized positions; the hydroxy protons in 5 were
3.3.1. (MenO)4Si (3), colorless solid, m.p. 96 °C
1H-NMR (CDCl3): l 3.65 (1H, td; H-1), 2.32 (1H, m;
H-7), 2.10 (1H, m; H-6), 1.61 (1H, m; H-3), 1.56 (1H,
m; H-4), 1.33 (1H, m; H-5), 1.18 (1H, m; H-2), 1.05
(1H, m; H-6%) 0.95 (1H, m; H-3), 0.90 (3H, d; H-8), 0.89
(3H, d; H-9), 0.86 (1H, m; H-4), 0.74 (3H, d; H-10).
13C-NMR (CDCl3): l 73.2 (C-1), 49.7 (C-2), 44.9 (C-6),
34.5 (C-4), 31.7 (C-5), 25.1 (C-7), 22.7 (C-3), 22.3 (C-8),
21.3 (C-9), 15.6 (C-10). 29Si-NMR (CDCl3): l −86.0.
29Si MAS-NMR: l −83.2.
Anal. Calc. for C40H76O4Si (649.13): C, 70.01; H,
11.80. Found: C, 70.15; H, 11.85%.