1-Phenyl-1-X-1-silacyclohexanes (X = MeO, OH, Me2N)

Article abstract of DOI:10.1134/S1070363217070349

By the reaction of nucleophilic substitution of chlorine in 1-phenyl-1-chloro-1-silacyclohexane new 1-phenyl-1-X-1-silacyclohexanes (Х = , ОН, Ме₂N) have been synthesized and their stability with respect to the formation of (1,1′-phenyl-1,1′-silacyclohex-1-yl)disiloxane have been investigated.

Full text of DOI:10.1134/S1070363217070349

ISSN 1070-3632, Russian Journal of General Chemistry, 2017, Vol. 87, No. 7, pp. 1645–1648. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © Е.N. Suslova, B.А. Shainyan, 2017, published in Zhurnal Obshchei Khimii, 2017, Vol. 87, No. 7, pp. 1218–1221.
LETTERS
TO THE EDITOR
1
-Phenyl-1-X-1-silacyclohexanes (Х = МеО, ОН, Ме N)
2
Е. N. Suslova and B. А. Shainyan*
A.E. Favorskii Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
*
e-mail: bagrat@irioch.irk.ru
Received April 24, 2017
Abstract―By the reaction of nucleophilic substitution of chlorine in 1-phenyl-1-chloro-1-silacyclohexane new
-phenyl-1-X-1-silacyclohexanes (Х = МеО, ОН, Ме N) have been synthesized and their stability with respect
1
2
to the formation of (1,1'-phenyl-1,1'-silacyclohex-1-yl)disiloxane have been investigated.
Keywords: 1-phenyl-1-methoxy(hydroxy, dimethylamino)-1-silacyclohexanes, hydrolytic stability
DOI: 10.1134/S1070363217070349
Silacyclohexanes having various labile substituents
at silicon are of interest from the viewpoint of further
functionalization by substitution of nucleofuge groups
under the action of nucleophiles or, in the case of
Si–Ph-substituted derivatives, by dephenylation under
the action of electrophiles. These compounds are of
specific interest for conformational analysis because of
principally different factors determining conforma-
tional preferences of axial and equatorial conformers
in cyclohexanes and in sila(hetero)cyclohexanes [1].
Recently we described the synthesis of 1-phenyl-1-
halogeno-1-silacyclohexanes [2] and their conforma-
tional analysis [3].
describe the synthesis of new silacyclohexanes of
general formula (CH ) Si(Ph)X (Х = MeO, OH,
2
5
Ме N) based on 1-phenyl-1-chloro-1-silacyclohexane.
2
Note, that 1-methoxy-1-phenyl-1-silacyclohexane 1
was recently prepared by the reaction of 1,1-dimethoxy-
1
-silacyclohexane with phenylmagnesium chloride, but
1
only as a crude product characterized by Н NMR
spectroscopy [9]. We have synthesized 1-methoxy-1-
phenyl-1-silacyclohexane 1 by the reaction of 1-phenyl-
1
-chloro-1-silacyclohexane 2 with sodium methoxide
in dry methanol in 61% yield by the protocol described
in [4]. The reaction is carried out at reflux and is
completed in 1 h, as was shown by monitoring the
1
13
Disubstituted at silicon silacyclohexanes are known
for a long time, and they include both symmetrically
reaction mixture by Н and С NMR spectroscopy by
1
3
the disappearance of the SiCH signal in С NMR
2
substituted (CH ) SiX (X = H, Me, MeO, OH, Cl) and
2
5
2
spectrum of compound 2 at 15.6 ppm and the
asymmetrical ones (CH ) Si(X)Y (X = H, Y = Me; X =
2
5
appearance of a new SiCH signal at 12.1 ppm and
2
H, Y = Cl; X = Me, Y = Cl) [4]. Among numerous sila-
cyclohexanes synthesized later using various
modifications of the procedure described in [4] there are
only a few compounds possessing the Si–Ph bond [2,
МеО group at 50.6 ppm, and of the signal of the МеО
group in the Н NMR spectrum at 3.54 ppm. From the
GC-MS data, the product contained ~2% of disiloxane
1
3
(m/z 366) (Scheme 1).
5
–8]. In view of our interest to the synthesis, chemical
transformations, and structural properties of Si-phenyl-
substituted silacyclohexanes, in the present work we
After a vacuum distillation, the highest-boiling
fraction contains up to 12% of disiloxane 3, whose
Scheme 1.
Ph Ph
Ph
Ph
MeONa
Si
Si
+
Si
Si
MeOH, Δ, 1 h
O
Cl
OMe
2
1 (61%)
3 (~2%)
1
645

1
646
SUSLOVA, SHAINYAN
1
NMR spectra coincide with those described by us
earlier [2]. The H NMR spectrum of compound 1 is
From the data of Н NMR spectroscopy, the reac-
1
tion is completed after keeping the reaction mixture for
identical to that described in [9].
2 h at 0°С and then 1 h at room temperature. The IR
–
1
spectrum of the product shows a band at 2788 cm
belonging to the stretching С–Н vibrations of the
Most of the methods of the synthesis of silanols are
based on the reaction of hydrolysis of compounds
having different groups at silicon (RSO , OCN, OR,
–
1
Me N group and a strong band at 986 cm , apparently,
2
3
1
due to Si–N bond vibrations [14]. In the Н NMR
R N, Cl, etc. [10]). For the synthesis of 1-hydroxy-1-
2
spectrum of compound 5 the Ме NSi group is
2
phenyl-1-silacyclohexane 4 we used the procedure of
two-phase hydrolysis of silane 2 using the method
proposed by Sommer [11] and used later on for the
hydrolysis of different silanes [12, 13].
characterized by a singlet at 2.61 ppm. An attempt to
characterize the product by GC-MS gave mass
spectrum of disiloxane 3 {m/z 366 (12) [M] and 289
(
100) [М – Рh]}, which is indicative of an easy
The hydroxy group in silanol 4 is displayed in the
IR spectrum as a strong wide band at 3274 cm
hydrolysis of aminosilane 5. This is also proved by
gradual hydrolysis of 5 at room temperature in neat
–
1
belonging to the vibrations of associated ОН groups,
which give a broadened singlet in the Н NMR
form or in solution in CDCl : after 1 month the
content of disiloxane 3 reaches 35–45%, after
3
1
spectrum at 3.10 ppm. Most convenient for monitoring
2 months the compound is fully hydrolyzed.
2
,6
the reaction is the disappearance of the signal of С
Aminosilane 5 was isolated by vacuum distillation.
An attempt to purify crude product by column
chromatography led to complete decomposition of
aminosilane 5, yet not to siloxane 3, but to silanol 4,
whose spectral characteristics coincided to those of the
authentic sample.
1
3
atoms in the С NMR spectrum of initial silane 2 at
5.65 ppm and the appearance of the signal of silanol 4
1
at 14.10 ppm. Silanol 4 was purified by column
chromatography, because thermal instability of mono-
silanols to distillation was well known [4].
Silanols are prone to intermolecular condensation
with the formation of stable siloxanes. Indeed, after 3
days of storage of silanol 4 in argon at room
Therefore, we have prepared for the first time new
-phenyl-1-X-1-silacyclohexanes (Х = МеО, ОН,
1
Ме N), which are interesting objects for further
2
1
3
temperature the С NMR spectrum showed the signal
conformational analysis. The structure of products was
2
,6
1
13
29
of disiloxane 3 at 15.02 ppm (С , 12%), and the IR
proved by the methods of IR and Н, С and Si
NMR spectroscopy, mass spectrometry, and elemental
analysis. The stability of 1-hydroxy-1-phenyl-1-
silacyclohexane against transformation to (1,1'-phenyl-
spectrum contained the absorption band of the siloxane
–
1
group at 1066 cm . Carrying out the reaction in the
presence of triethylamine slightly decreases the yield
of the target silanol but increases its stability due to the
removal of traces of HCl: after 1.5 months of storage
at room temperature the NMR spectra of silanol 4 did
not change.
1
,1'-silacyclohex-1-yl)disiloxane was investigated. It
was shown that 1-dimethylamino-1-phenyl-1-sila-
cyclohexane depending on the conditions is readily
hydrolyzed to 1-hydroxy-1-phenyl-1-silacyclohexane
or (1,1'-phenyl-1,1'-silacyclohex-1-yl)disiloxane. The
obtained results are indicative of a sharp decrease in
the stability of the synthesized 1-phenyl-1-X-1-
silacyclo-hexanes in the series Х = МеО >> ОН >>
_
KOH, H O Et O
2
2
Ph
Cl
0°C, 30 min
Ph
Si
Si
Si
_KCl
OH
2
2
4 (77%)
Мe N.
2
Ph
_
Ph
hexane, 0 20°C
1-Methoxy-1-phenyl-1-silacyclohexane (1). To a
solution of sodium methoxide (0.532 g of sodium
metal, 0.023 g-equiv) in 11 mL of dry methanol 4.50 g
+ 2 Me NH
Si
2
_
Me NH HCl
2
Cl
NMe2
5 (56%)
(
0.021 mol) of 1-phenyl-1-chloro-1-silacyclohexane
General method for the formation of the Si–N bond
is the substitution of chlorine in chlorosilanes by the
reaction with amines [14–16]. We obtained 1-dimeth-
ylamino-1-phenyl-1-silacyclohexane 5 in 56% yield by
the reaction of chlorosilane 2 with dimethylamine in
hexane at 0°С.
was added dropwise during 20 min, then 5 mL of dry
ether was added and the reaction mixture was refluxed
with stirring for 1 h. The organic phase was separated
from the precipitate using inverse Schott filter, the
solvents were removed at a reduced pressure, the
residue was distilled in a vacuum, bp 141–143°С
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 7 2017

1
-PHENYL-1-X-1-SILACYCLOHEXANES (Х = МеО, ОН, Ме
2
N)
1647
(
15 mmHg). Yield 2.677 g (61%). IR spectrum (film),
mentation of the precipitate the solution was filtered
through the inverse Schott filter and the solvent and
volatile components were removed at 20 mmHg. The
residue had slightly alkaline reaction (рН 7.5–8).
Vacuum distillation gave 0.682 g (56%) of compound
5 with bp 140–142°С (5 mmHg). IR spectrum (film),
–
1
ν, cm : 3088, 2918, 2830, 1428, 1115, 1086, 794–699.
1
Н NMR spectrum, δ, ppm: 1.01 d. d. d (2Н, SiСНА,
J = 14.7, 9.2, 4.7 Hz), 1.10 d. d. d (2Н, SiСН , J =
1
m (1H, СH ), 1.75–1.95 m (4Н, СН ), 3.53 s (3Н,
В
4
4.7, 8.0, 4.8 Hz), 1.45–1.56 m (1H, СH ), 1.57–1.67
А
4
3,5
В
2
m,p
o
–1
ОМе), 7.45–7.46 m (3Н, H ), 7.66–7.67 m (2Н, H ).
ν, cm : 3061, 2912, 2788, 1480, 1286, 1177, 1109,
1
3
2,6
3,5
1
С NMR spectrum, δ , ppm: 12.11 (C ), 24.23 (C ),
1071, 986, 701. Н NMR spectrum, δ, ppm: 1.05 t (4Н,
С
4
p
m
4
2
1
3
1
%
%
9.77 (C ), 50.62 (СН О), 127.84 (C ), 129.65 (C ),
SiСН , J = 6.6 Hz), 1.56 m (2H, H ), 1.67–1.79 m (2Н,
3
2
3,5
o
i
29
3,5
33.71 (C ), 135.83 (C ). Si NMR spectrum: δSi
СНА ), 1.80–1.91 m (2Н, СН ), 2.61 s (6Н, Me N),
В 2
m,p
o
13
.67 ppm. Mass spectrum, m/z (I , %): 206 (9) [M],
7.43 m (3Н, H ), 7.61 m (2Н, H ). С NMR
spectrum, δ , ppm: 11.84 (C ), 24.34 (C ), 30.09
(C ), 38.19 (Ме N), 127.70 (C ), 128.94 (C ), 133.90
2
(C ), 137.93 (C ). Si NMR spectrum: δSi –4.48 ppm.
Found, %: С 71.22; H 9.47; N 6.67; Si 12.62.
C H NSi. Calculated, %: C 71.18; H 9.65; N 6.38; Si
rel
2
,6
3,5
63 (39), 128 (100) [M – Ph], 105 (22) [PhSi]. Found,
С
4
p
m
: С 69.61; H 8.89; Si 13.77. C H OSi. Calculated,
12
18
o
i
29
: C 69.85; H 8.79; Si 13.60.
1
-Hydroxy-1-phenyl-1-silacyclohexane (4). To a
1
3
21
solution of 0.53 g (9.5 mmol) of KOH in 9 mL water
at 0°С and vigorous stirring a cooled solution of
1
2.79.
1
-phenyl-1-chloro-1-silacyclohexane (2 g, 9.5 mmol)
IR spectra were taken on Bruker Vertex 70 and
1
13
29
in 30 mL of dry ether was added dropwise in the
course of 1 h. The reaction mixture was stirred at 0°С
for 0.5 h, then warmed to room temperature. The two-
layer system was separated in a separating funnel,
ether layer was washed with water to рН 7 and dried
over Na SO . After removal of ether at a reduced
Varian 3100 FT-IR instruments. Н, С, and Si
NMR spectra were registered on a Bruker AVANCE
spectrometer 400 (400, 100, and 80 MHz respectively)
in CDCl solution. Mass spectra of electron ionization
3
(70 eV) were obtained on a GCMS-QP5050A Shimadzu
chromatomass spectrometer with quadruple mass
analyzer (capillary column Ultra 2, 0.2 mm × 50 m,
gas carrier – helium). Column chromatography was
carried out on silica Merck (Geduran) with TLC
control on silica plates 60 F-254. The reaction progress
2
4
pressure and additional drying in a vacuum 1.413 g
77%) of compound 4 was isolated as a thick oil.
(
Analytically pure product was obtained by column
chromatography on silica (hexane, hexane–ether, 2 : 1,
R 0.09). IR spectrum (film), ν, cm : 3274 br. s
–
1
1
13
was monitored by H and C NMR spectroscopy. The
solvents were purified and dried by standard
procedures and stored over molecular sieves 4 Å. All
reactions were performed in a dry argon atmosphere.
f
(
(
(
(
ОН ), 3066, 2915, 2854, 1432, 1116 (Si–Ph), 1066
Si–OH). Н NMR spectrum, δ, ppm: 0.90–1.05 m
4Н, SiСН ), 1.40–1.52 m (1H, CH ), 1.53–1.63 m
1H, CH ), 1.70–1.90 m (4Н, СН ), 2.24 br. s (1H,
ass
1
4
2
A
4
3,5
B
2
m,p
o
ACKNOWLEDGMENTS
ОН), 7.43–7.45 m (3Н, H ), 7.63–7.66 m (2Н, H ).
1
3
2,6
3,5
С NMR spectrum, δ , ppm: 14.10 (C ), 24.24 (C ),
С
This work was performed using the equipment of
the Baikal Center for Joint Usage of Siberian Branch
of Russian Academy of Sciences. The authors are
grateful to Dr. S.V. Kirpichenko (Irkutsk Institute of
Chemistry) for drawing the attention to some
references and discussion of the results.
4
p
m
o
2
1
9.66 (C ), 127.73 (C ), 129.50 (C ), 133.38 (C ),
i
29
37.44 (C ). Si NMR spectrum: δ 1.29 м. д. Mass
Si
spectrum, m/z (I , %): 192 (11) [M], 149 (36) [M –
C H ], 136 (33) [149 – CH], 123 (38) [136 – CH], 114
rel
3
7
(
100) [M – C H ]. Found, %: С 68.70; H 8.67; Si
6 6
1
1
4.53. C H OSi. Calculated, %: C 68.71; H 8.39; Si
11 16
4.59.
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