The products of substitution and cyclization in the reaction of (2-bromoethyl)(3-chloropropyl)dimethylsilane with triflamide

Article abstract of DOI:10.1134/S1070363213030080

In order to synthesize the first seven-membered N-triflylazasilacycloalkane the reaction of triflamide with (2-bromoethyl)(3-chloropropyl)dimethylsilane was studied. Depending on the reaction conditions bis(3-chloropropyl) tetramethyldisiloxane, 3-trifluo

Full text of DOI:10.1134/S1070363213030080

ISSN 1070-3632, Russian Journal of General Chemistry, 2013, Vol. 83, No. 3, pp. 453–461. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © E.N. Suslova, A.I. Albanov, B.A. Shainyan, 2013, published in Zhurnal Obshchei Khimii, 2013, Vol. 83, No. 3, pp. 399–407.
The Products of Substitution and Cyclization in the Reaction
of (2-Bromoethyl)(3-chloropropyl)dimethylsilane
with Triflamide
E. N. Suslova, A. I. Albanov, and B. A. 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 October 18, 2012
Abstract―In order to synthesize the first seven-membered N-triflylazasilacycloalkane the reaction of
triflamide with (2-bromoethyl)(3-chloropropyl)dimethylsilane was studied. Depending on the reaction
conditions bis(3-chloropropyl)tetramethyldisiloxane, 3-trifluoromethylsulfonylaminopropyl(3-chloropropyl)-
tetramethyldisiloxane, (2-triflamidoethyl)(3-chloropropyl)dimethylsilane, bis(3-triflamidopropyl)tetramethyldi-
siloxane, and the target 4,4-dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilepane have been isolated. In all
1
cases the halogen atom in the β-bromoethyl group is replaced first. Low-temperature H NMR spectroscopy
showed that the prepared seven-membered heterocycle is conformationally flexible.
DOI: 10.1134/S1070363213030080
Heterocyclic compounds with the nitrogen and
silicon atoms in 1,3- and 1,4-positions of the ring as
well as their derivatives have been actively studied in
two recent decades since they possess interesting
chemical properties, different types of biological
activity showing hypotensive, ganglion blocking,
neurotropic, and other effects [1–7] and demonstrate
an interesting conformational behavior [8–11].
Trimethyl-1-phenyl-1,4-azasilepane was obtained in an
extremely low yield (3%) in the reaction of aniline
with chloropropyl(allyl)dimethylsilane [18], and its 2-
unsubstituted analog was synthesized in 36% yield by
the reaction with vinyl(3-phenylaminopropyl)dimethyl-
silane [19]. A complex condensed heterocycle, an ester
of 5,5-dimethyl-8,9-dioxo-1-aza-5-silabicyclo[5.2.0]no-
nane-2-carboxylic acid, was decomposed with the forma-
tion (among other products) of two simpler seven-
membered Si,N-heterocycles, the esters of 4,4-di-
methyl-1,4-azasilepane-7-carboxylic and -2,7-dicar-
boxylic acids [22]. The stereocontrolled synthesis of a
series of six-membered Si,N-heterocycles as well as
their seven-membered analog, (R)-benzyl-3,3-
In general, the synthesis of five- and six-membered
organosilicon azaheterocycles is mainly performed by
the reaction of ω,ω'-di(haloalkyl)silanes with amines,
or by the method of intramolecular cyclization of (ω-
haloalkyl)(ω'-aminoalkyl)silanes, which can be
considered as intermediates in the former reaction
[2, 3, 12–19].
diphenyl-2-propyl-1,3-azasilepane-1-carboxylate
in
good yield has been described [23]. In the latter case,
the nitrogen atom is protected by the carboxybenzyl
group. We failed to find seven-membered Si,N-
heterocycles bearing a protecting sulfonyl group at the
nitrogen atom, although their organic analogs, such as
1-tosylazepane, are well known and were prepared by
the base-catalyzed cyclization of N-(6-bromoalkyl)-
sulfonamides [24].
The synthesis of seven-membered Si,N-hetero-
cycles was always a challenge, that is why there are
few examples of their synthesis. Thus in [20] the
synthesis of l-butyl-3,3-dimethyl-3-sila-l-azasilacyclo-
heptane from δ-bromobutyl(bromomethyl)dimethyl-
silane and butylamine in 43% yield was described.
Mironov et al. [21] have synthesized the organosilicon
lactam, 3,3-dimethyl-1,3-azasilepan-7-one, in 70%
yield by heating 4-[(chloromethyl)dimethylsilyl]butan-
amide with sodium methoxide in methanol. 2,4,4-
In the course of our studies on the synthesis and
investigation of the properties of N-triflyl substituted
453

454
SUSLOVA et al.
Si,N-heterocycles based on the reaction of hetero-
cyclization of dimethyldi(ω,ω'-haloalkyl)silanes with
trifluoromethanesulfonamide (triflamide) we have
synthesized new five- and six-membered Si,N-
heterocycles with the endocyclic nitrogen and silicon
atoms possessing the triflyl group at nitrogen [25–27].
The reactions were performed in the presence of
triethylamine, the products were formed in moderate
yields of 42–50%. In the present work, with the aim to
synthesize the seven-membered analog of the earlier
obtained N-triflylazasilacycloalkanes the reaction of
triflamide I with (2-bromoethyl)(3-chloropropyl)di-
methylsilane II has been studied. The starting silane II
was prepared by the free-radical hydrobromination of
(3-chloropropyl)dimethyl(vinyl)silane in 83% yield by
the known procedure [13].
The reaction of silane II with the sodium salt of
triflamide in THF proceeds similar to reaction (2) (the
reaction was carried out in the presence of the phase
transfer catalyst triethylbenzylammonium chloride
because the salt was insoluble in THF).
In methanol, as in THF, the reaction does not occur
at room temperature. At reflux over 7 h in the presence
of triethylamine the starting silane II is completely
consumed. According to the NMR spectroscopy data,
the reaction mixture contains mainly siloxanes. By the
use of column chromatography, we succeeded to
isolate siloxane III (yield 10%) and the product of
substitution of one chlorine atom in it by the triflamide
residue, 3-trifluoromethylsulfonylaminopropyl(3-chloro-
propyl)tetramethyldisiloxane (IV) (yield 3.5%).
CF3SO2NH2, Et3N
CH2CH2CH2Cl
III
II
HBr
+
Me2Si
MeOH, Δ
CH2
CH
+
CF3SO2NH(CH2)3Si(Me2)OSi(Me2)(CH2)3Cl
(3)
CH2CH2CH2Cl
IV
(PhCOO)2
hexane, Ar
(1)
Me2Si
Apparently, complete conversion of silane II in
CH2CH2Br
methanol, as distinct from the reaction in THF, is due
to an easier cleavage of the Si–C bond in the
bromoethyl fragment (β-effect) in a proton-donor
medium [28]. This was confirmed by an independent
synthesis of siloxane III: it was obtained by the reflux
of silane II in methanol and isolated by column
chromatography in 36% yield. Siloxane III can react
with triflamide to afford unsymmetrical disiloxane IV.
The structure of siloxanes III and IV was proved by
II
The attempt to perform the reaction of silane II
with triflamide under the conditions optimal for the
synthesis of the earlier prepared five- [27] and six-
membered cycles [26] (THF, I:II:Et3N = 2:1:2) failed.
At room temperature or in the absence of triethylamine
the reaction does not proceed, and only after reflux for
7–13 h the conversion was 47–50%. Therewith no
fluorine-containing products were detected by the
1Н and 19F NMR spectroscopy. From the 29Si NMR
spectroscopy, the reaction mixture, apart from the
starting silane II, contained silanols (δSi ~15 ppm) and
siloxanes (δSi ~8 ppm), in particular, bis(3-chloro-
propyl)tetramethyldisiloxane (III).
1
NMR spectroscopy. The Н and 13С NMR spectra of
symmetrical siloxane III contain the signals of the
SiМе2 group and three signals of the methylene groups
of the Si(CH2)3Сl fragment, and the 29Si NMR
spectrum contains one signal at 7.64 ppm. In the un-
symmetrical siloxane IV the number of signals in all
NMR spectra is doubled due to the presence of two
nonequivalent fragments Si(CH2)3Сl and Si(CH2)3N.
CH2CH2CH2Cl
Me2Si
The assignment of the signals in the Н and 13С NMR
1
spectra to the chloropropyl and the triflamidopropyl
fragments was performed by the use of two-dimen-
CH2CH2Br
II
1
1
sional spectra Н–1Н COSY and Н–13С HSQC and
CF3SO2NH2, Et3N
was based on different splitting pattern of the CH2Cl
and CH2N signals in the Н NMR spectra: the former
(2)
[Cl(CH2)3Si(Me2)]2O
1
THF, Δ
signal is a triplet, whereas the latter one is a quartet
due to close coupling constants 3JCH–CH and 3JCH–NH
.
III
Earlier we have shown that the reaction of tri-
flamide with (chloromethyl)trimethylsilane is sharply
retarded when performed in THF or methanol in the
The formation of siloxane III was proved by the
coincidence of the signals of the reaction mixture with
the signals of the independently synthesized sample.
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THE PRODUCTS OF SUBSTITUTION AND CYCLIZATION
455
presence of excess triethylamine as compared to the
reaction in triethylamine as a solvent [29]. The same
effect was observed in the reaction of triflamide with
silane II. The composition of the products formed did
not change qualitatively when the reaction was carried
out in triethylamine. At room temperature the reaction
does not take place, but upon heating to 50–60°С a
spontaneous heating of the reaction mixture to 70–90°С
occurs and after 3 h at 70–75°С the conversion of the
starting silane II reaches 100%. The reaction with
small excess of triflamide with respect to silane II
leads to the formation of (2-triflamidoethyl)(3-chloro-
propyl)dimethylsilane (V), bis(3-triflamidopropyl)tetra-
methyldisiloxane (VI), and 4,4-dimethyl-1-(trifluoro-
methylsulfonyl)-1,4-azasilepane (VII) according to
reaction (4).
CH2CH2CH2Cl
CF3SO2NH2
Me2Si
[CF3SO2NH(CH2)3Si(Me2)]2O
+
II
Et3N, Δ
CH2CH2NHSO2CF3
VI
V
H3C
Si
(4)
N
+
SO2CF3
H3C
VII
1
The results of monitoring reaction (4) by Н NMR
spectroscopy are presented in the table.
according to NMR data, in up to 50% yield.
Apparently, this is due to a lower rate of cyclization of
compound V because of more remote groups NH and
СН2Cl.
Compound V is the intermediate on the way of
transformation of silane II to the product of hetero-
cyclization VII. This process is general for dihalo-
silanes Me2Si(CH2CH2Br)(CH2)nX [reaction (5)].
Products V–VII were isolated as individual
compounds by column chromatography, their structure
1
In all cases, the halogen atom in the β-bromoethyl
group is replaced first, but the five- and six-membered
heterocycles are formed immediately, so that the
intermediate products of monosubstitution cannot be
even detected in the reaction mixture, whereas in the
synthesis of the seven-membered cycle it is formed,
and composition was proved by IR, Н, 13С, 19F, 29Si
NMR spectroscopy and elemental analysis, and by
1
independent synthesis. Thus, in the Н and 13С NMR
spectra of the product of monosubstitution V, apart
from the signals of the Me2Si group, the signals of five
different methylene groups are observed, in the IR and
(CH2)n
Me
(CH2)nX
(CH2)2NHSO2CF3
(CH2)nX
(CH2)2Br
CF3SO2NH2
Me2Si
(5)
Si
SO2CF3
Me2Si
N
Et3N, Δ
_HX
Me
n = 1, X = Cl [27]; n = 2, X = Br, [26]; n = 3, X = Cl.
Conditions of reaction (4) and yields of the products
II : Et3N
1:4
Time, h
Т, °С
72
Conversion, %
V, %
39
VI, %
30
VII, %
1
72
84
3
14
1:4
2
72
40
30
1:4
3
72
100
80
50
34
16
1:7
0.5
6
80–86
85–90
12
45
Tracesа
20b
1:4
100
Traces
70
а Yield of unidentified products of decomposition 23%. b Yield of unidentified products of decomposition 10%.
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SUSLOVA et al.
1Н NMR spectra the NH signal is present, and the 13С
and 19F NMR spectra contain the signal of the CF3
group. Note the absence of the product of
monosubstitution of chlorine atom in silane II, which
is indicative of a higher reactivity of the β-bromoethyl
group as compared to the γ-chloropropyl group. Since
in reaction (4) the precipitate comprising the mixture
of hydrohalides Et3N·HCl and Et3N·HBr is formed, for
the independent assessment of the relative reactivity of
the γ-chloropropyl and β-bromoethyl groups we have
used the method of X-ray energy dispersive
microanalysis and examined the specimens taken after
30 min and after 2 h from the beginning of the
reaction. After 30 min the averaged ratio Br/Cl in the
mixture of the salts was 2:1, whereas after 2 h it was
1:6, that is, in the first step the substitution takes place
in the 2-bromoethyl group and only then in the 3-
chloropropyl group.
column chromatography was 37%, and of heterocycle
VII, 16%. Compounds V and VII containing the
triflamide residue in the β-position to the silicon atom,
are rather stable and do not decompose at storage for
half a year.
1
In the Н NMR spectrum of compound VII in
CDCl3 at room temperature four signals are observed:
broadened singlets at 0.8 and 1.1 ppm belonging to the
SiCH2 groups in the (СН2)3 and (СН2)2 fragments,
respectively, a multiplet of the ССН2С group, and a
very broad signal at 2.5–4.5 ppm belonging to two
nonequivalent NCH2 groups. The observed broadening
is caused by the lability of the seven-membered ring.
When the temperature of the sample was increased to
70°С, the solution was degassed, and the spectrum was
taken in an argon atmosphere, the SiCH2 signals
showed a multiplet structure and the NCH2 signals
appeared as two separate broadened singlets at 3.4 and
3.6 ppm. Two-dimensional homonuclear spectrum 1Н–
1Н COSY at 70°С allowed to unambiguously assign all
signals: the protons of the 6-СН2 group give cross
peaks with the protons of the 5-SiCH2 and 7-NCH2
groups, and the protons of the 3-SiCH2 group, with the
protons of the 2-NCH2 group.
The positions of the methylene group signals in the
1Н NMR spectra of siloxanes VI and III practically
coincide. The difference is that the spectrum of
siloxane VI contains the triplet of the NH group, and
the signal of the NCH2 looks like a quartet due to
additional splitting on the NH proton, rather than a
triplet as in the spectrum of compound III. Siloxane
VI is, apparently, the product of bis-triflamidation of
siloxane III, which is an intermediate formed by β-
cleavage of silane II. Indeed, an independent experi-
ment has shown that siloxane III reacts with triflamide
The observed variations in the 1Н NMR spectrum at
higher temperatures prompted us to investigate the
dynamics of the process at low temperatures. The
results are shown in Fig. 1. As follows from the
spectra, all signals are split to the sgnals of the axial
and equatorial Si-methyl groups and the axial and
equatorial protons of the methylene groups of the ring.
From the temperature of coalescence and the dif-
ference in the chemical shifts of the signals of protons
of the 2-СН2, 3-СН2, 5-СН2, 7-СН2 groups as well as
of the SiМе protons and using the Eyring equation,
where k = Δν/0.45, the free energy was calculated. It
turned out to be practically the same for all pairs of the
signals and was equal to 13.5 kcal/mol.
1
to give siloxane VI in 90% yield, as shown the Н
NMR spectroscopy data.
III
CF3SO2NH2
VI
+
(6)
Et3N, Δ
Siloxane III was also detected under the conditions
of reaction (4) in the initial stage (15–30 min) at a
lower temperature (below 63°С).
The use of 7-fold excess of triethylamine
accelerates reaction (4): the conversion reaches 80%
after 30 min. The content of product V decreases to
12%, but the product of heterocyclization VII is
present only in trace amounts. Therewith, the content
of siloxane VI increases to 45% (see the table),
apparently, due to a faster β-cleavage of the starting
silane II. The optimal conditions for preparation of
heterocycle VII were found to be the following: the
use of the ratio II:I:Et3N = 1:2:4 and reflux at 85–90°С
in the course of 6 h. Under these conditions, according
to the 1Н NMR data, the conversion was 100% and the
reaction mixture contained only products VI and VII
in the ratio 7:2. The isolated yield of siloxane VI after
ΔGc≠ = 1.986Tc[23.76 + 2.303(log Tc – log k)].
Apparently, this value is a barrier to the ring
inversion, but the structure and the energy of the
interconverting conformers is the subject of a separate
investigation in view of the presence of two hetero-
atoms in the seven-membered ring, which may occupy
different nonequivalent positions, and the triflyl group
which may be differently oriented with respect to the
ring. Equilibrium (7) illustrates only one of many
possibilities.
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THE PRODUCTS OF SUBSTITUTION AND CYCLIZATION
457
(7)
In Fig. 2, the low-temperature 1Н–1Н COSY
spectrum of heterocycle VII is given in the range of
protons of the ring methylene groups. The pattern of
splitting and the presence of the corresponding cross
peaks allow an unambiguous assignment of the
observed signals to the axial and equatorial protons in
the ring. As is seen, in accordance with the general
rule, in all cases the axial protons resonate at a stronger
field. All signals are completely resolved, except for
the overlapping signals of the 5-CНeq and 3-CHax
protons at 0.9 ppm.
used for the cyclization of (γ-hydroxy)-α-silylamines
and their derivatives [23] failed; even upon heating to
50°С in the course of 5 h the starting product V was
recovered, probably, due to the low basicity of the
triflamide nitrogen atom.
EXPERIMENTAL
1Н, 13С, 19F, and 29Si NMR spectra were recorded
from CDCl3 solutions on a Bruker DPX 400 spectro-
meter (400, 100, 376, and 79.5 MHz, respectively).
Chemical shifts are given relative to TMS (1Н, 13С,
29Si) and CCl3F (19F). The assignment of the signals in
1Н and 13С NMR spectra was performed by the use of
An attempt to perform cyclization of compound V
by the action of NaH in THF employing the procedure
δ, ppm
Fig. 1. 1Н NMR spectra of 4,4-dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilepane (VII) in CDCl3 in the temperature range from
70 to –70°С.
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458
SUSLOVA et al.
δ, ppm
Fig. 2. 1Н–1Н COSY spectrum of 4,4-dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilepane (VII) at –70°С in CDCl3.
1
1
two-dimensional spectra Н–1Н COSY, Н–13С HSQC
and 1Н–13С HMBC. IR spectra were taken on a Bruker
Vertex 70 spectrometer in thin layer. X-ray energy
dispersive microanalysis was performed on a RES
Hitachi TM 3000.
m (2Н, CН2CН2Br), 1.76 m (2H, CCH2C), 3.50 t (2Н,
3
CН2Сl, J 7.0 Hz), 3.55 m (2H, CH2Br). 13С NMR
spectrum, δC, ppm: –3.68 (SiMe), 12.58 (SiCСC),
22.31 (SiCСBr), 27.50 (CCC), 31.24 (CBr), 47.63
(CCl). 29Si NMR spectrum: δSi 2.62 ppm. The assignment
is proved by the presence of cross peaks between the
signals at 0.67 and 1.76 ppm, 1.76 and 3.50 ppm, 1.49
and 3.55 ppm in the 1Н–1Н COSY spectrum, and in the
1Н–13С HSQC spectrum, by the presence of the cross
peaks between the signals at 0.67, 1.49, 1.76, 3.50 and
(2-Bromoethyl)(3-chloropropyl)dimethylsilane (II).
Through a solution of 5.257 g (22 mmol) of (3-chloro-
propyl)dimethyl(vinyl)silane and 0.05 g (0.2 mmol) of
benzoyl peroxide in 40 ml of anhydrous hexane dried
gaseous HBr was bubbled in the course of 6 h in an
argon atmosphere under UV irradiation and stirring.
The reaction mixture was left overnight at room tem-
perature, the excess of НВr was removed by passing
argon, and hexane was distilled off at the atmospheric
pressure. After vacuum distillation of the residue 6.51 g
(83%) of silane II was isolated, bp 131–132°С
(10 mm Hg), nD25 1.4900. IR spectrum, ν, cm–1: 2954,
1
3.55 ppm in the Н NMR spectrum and the signals at
12.58, 22.31, 27.50, 47.63 and 31.24 ppm, respec-
tively, in the 13С NMR spectrum. Found, %: С 34.22;
Н 6.77; Br 32.85; Cl 14.57; Si 11.03. C7H16BrClSi.
Calculated, %: С 34.51; Н 6.62; Br 32.79; Cl 14.55; Si
11.49.
Reaction of (2-bromoethyl)(3-chloropropyl)di-
methylsilane with triflamide. а. To the solution of
0.436 g (1.8 mmol) of silane II and 0.533 g (3.6 mmol)
1
1420, 1250, 1030, 835. Н NMR spectrum, δ, ppm:
0.06 s (6Н, SiМе2), 0.67 m (2H, CH2CH2CH2Cl), 1.40
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THE PRODUCTS OF SUBSTITUTION AND CYCLIZATION
459
of triflamide I in 3 ml of anhydrous THF the solution
of 0.362 g (3.6 mmol) of triethylamine in 1 ml of THF
was added in an argon atmosphere in the course of
10 min. The reaction mixture was refluxed for 13 h,
then the solvent was removed. The residue, according
to the 1Н, 13С, 29Si, 19F NMR spectroscopy data, consisted
of the starting silane II (50%) and siloxane III (32%).
15.87 (SiC), 27.03 (СCС), 47.78 (CCl). 29Si NMR
spectrum: δSi 7.64 ppm.
3-Trifluoromethylsulfonylaminopropyl(3-chloro-
propyl)tetramethyldisiloxane (IV). Yield after chro-
matographic separation 3.5%, Rf 0.47. 1Н NMR
spectrum, δ, ppm: 0.09 s (6Н, SiМе2), 0.1 s (6Н,
SiМе2), 0.55 m (2Н, CН2СН2СН2N), 0.65 m (2Н,
CН2СН2СН2Cl), 1.67 m (2Н, NCH2СН2), 1.79 m (2Н,
ClCН2СН2), 3.30 m (2Н, NCН2), 3.53 m (2Н, ClCН2),
4.98 br. s (1Н, NН). 13С NMR spectrum, δС, ppm: 0.22
(SiMe); 14.93 (CССN), 15.80 (CССCl), 24.45 (СCN),
27.00 (ССCl), 47.09 (NС), 47.81 (ClС), 119.67 q (CF3,
1JCF 319.0 Hz). 19F NMR spectrum: δF –77.49 ppm.
29Si NMR spectrum, δSi, ppm: 7.81, 8.41. The
assignment is proved by the presence of cross peaks
between the signals at 0.55 and 1.67 ppm, 0.65 and
1.79 ppm, 1.67 and 3.30 ppm, and 1.79 and 3.53 ppm
b. To the solution of 0.345 g (1.4 mmol) of silane II
the solution of 0.422 g (2.8 mmol) of triflamide and
0.286 g (2.8 mmol) of triethylamine in 2 ml of
methanol was added dropwise during 15 min. The
reaction mixture was refluxed for 6–7 h, methanol was
removed, the residue was stirred with hexane, the
solution separated from the precipitate containing
triflamide, triethylamine salts and silanols. The hexane
solution was evaporated to give 0.08 g of liquid
1
residue, which contained, according to the Н, 19F
1
1
in the Н–1Н COSY spectrum, and in the Н–13С
HSQC spectrum by the presence of the cross peaks
between the signals at 0.55, 0.65, 1.67, 1.79, 3.30 and
NMR spectroscopy data, bis-(3-chloropropyl)tetramethyl-
disiloxane III, 3-trifluoro-methylsulfonylaminopropyl-
(3-chloropropyl)tetra-methyldisiloxane IV in the ratio
5:1, and unidentified impurities. Individual products
III and IV were isolated by column chromatography
on silica ICN by gradient elution with hexane–ether
from 100:1 to 1:1.
1
3.53 ppm in the Н NMR spectrum and the signals at
14.93, 15.80, 24.45, 27.00, 47.09 and 47.81 ppm,
respectively, in the 13С NMR spectrum. Found, %: С
32.60; Н 6.21; N 3.49; S 7.91. C11H25ClF3NO3SSi2.
Calculated, %: С 33.04; Н 6.25; N 3.50; S 8.01.
c. To the mixture of 0.884 g (3.6 mmol) of 3-chloro-
propyl(2-bromoethyl)dimethylsilane (II) and 1.08 g
(7.2 mmol) of triflamide 1.47 g (2.1 ml, 14.6 mmol) of
triethylamine was added dropwise at stirring in the
course of 15 min. The reaction mixture was heated till
the beginning of exothermic reaction (70°С), stirred
for 6.5 h at 88–92°С, cooled, 6 ml of water was added,
and the product was extracted with ether (3×3 ml). The
organic layer was dried over Na2SO4, solvent was
removed to obtain 1.243 g of crude product,
2-Trifluoromethylsulfonylaminoethyl(3-chloro-
propyl)dimethylsilane (V). To the mixture of 0.403 g
(1.65 mmol) of 2-bromoethyl(3-chloropropyl)di-
methylsilane II and 0.342 g (2.3 mmol) of triflamide
0.669 g (6.62 mmol) of triethylamine was added
dropwise in the course of 10 min. The reaction mixture
was heated to 50°С, then it spontaneously heated to
72°С and was stirred at this temperature for 3.5 h.
After the completion of the reaction, 8 ml of water was
added, the product was extracted with ether (3×3 ml),
the extract was dried over Na2SO4, the solvent was
removed to afford 0.341 g of crude product consisting,
1
consisting, according to the Н NMR data, of 4,4-
dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilepane
(VII) and siloxane VI in the ratio 2:7 and triethyl-
amine; no starting silane II was detected. The yield of
the crude product VII was 25%, of siloxane VI, 61%.
Analytically pure samples were obtained by column
chromatography on silica Geduran Si 60 (Меrck) in
the system hexane–ether, from 80:1 to 20:1.
1
according to the Н, 13С, 29Si, 19F NMR data, of
product V, a mixture of siloxanes (mainly VI), and
heterocycle VII in the ratio 3:2:1. Pure product V
(0.112 g, 22%) was isolated by column chromato-
graphy on silica (Geduran, Merck), with eluent
hexane–ether, from 10:1 to 1:1, Rf 0.45 (hexane:ether =
2:1). IR spectrum, ν, cm–1: 3317 (NH), 2456 (CH2),
1432 (SiC), 1372 (SO2), 1254 (SiMe), 1232, 1193
(CF3), 1146 (SO2), 1047 (SN), 911 (CN), 736 (CCl),
Bis(3-chloropropyl)tetramethyldisiloxane (III).
The yield after chromatographic separation 10%, Rf
0.94. IR spectrum, ν, cm–1: 2957 (CH2), 1412 (SiC),
1
1
1257 (SiMe), 1051 (SiOSi), 796 (CН2Сl). Н NMR
606 (CF3). Н NMR spectrum, δ, ppm: 0.07 s (6Н,
spectrum, δ, ppm: 0.08 s (12Н, SiМе2), 0.63 m (4H,
SiМе2), 0.67 m (2H, SiCH2СН2СН2Cl), 0.98 m (2Н,
SiCН2СН2N), 1.76 m (2H, CH2СН2СН2), 3.36 m (2Н,
3
SiCH2), 1.79 m (4Н, CН2), 3.51 t (4Н, CН2Сl, J
7.0 Hz). 13С NMR spectrum, δС, ppm: 0.24 (SiMe),
3
CH2N), 3.52 t (2Н, CН2Сl, J 7.0 Hz). 13С NMR
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 83 No. 3 2013

460
SUSLOVA et al.
spectrum, δС, ppm: –3.66 (SiMe), 12.53 (SiCССCl),
17.82 (SiCСN), 27.25 (СCС), 41.51 (CN), 47.62 (CCl),
121.3 q (СF3, J 319.3 Hz). 19F NMR spectrum: δF
–77.42 ppm. 29Si NMR spectrum: δSi 2.04 ppm. Found,
%: С 30.51; Н 5.26; Cl 11.58; F 17.70; N 4.55; S
10.84. C8H17ClF3NO2SSi. Calculated, %: С 30.81; Н
5.49; Cl 11.37; F 18.28; N 4.49; S 10.28.
1.5 ml of methanol was refluxed for 6 h, methanol was
removed to afford 0.202 g of the liquid residue
1
containing, according to the Н, 13С, 29Si NMR data,
74% of siloxane III. Pure siloxane III was isolated by
column chromatography on silica, eluent hexane–ether
(from 8:1 to 1:1) in 47% yield. Physicochemical
constants coincided with the literature data [30], NMR
spectra were identical to those for the samples obtained
in methanol and THF.
Bis(3-trifluoromethanesulfonylaminopropyl)tetra-
methyldisiloxane (VI). Yield after chromatographic
separation 37%, Rf 0.61. IR spectrum, ν, cm–1: 3316
(NH), 2957 (CH2), 1434 (SiC), 1371 (SO2), 1257
(SiMe), 1239 (CF3), 1192 (CF3), 1147 (SO2), 1069
(SN), 1050 (SiOSi), 841 (CN), 797 (CS), 610 (CF3).
1Н NMR spectrum, δ, ppm: 0.01 s (12Н, SiМе2), 0.55
m (4Н, SiCН2), 1.64 m (4Н, CCН2C), 3.28 q (4Н,
NCН2, J 6.7 Hz), 5.20 br. t (2Н, NН J 6.2 Hz). 13С
NMR spectrum, δС, ppm: 0.04 (SiMe), 14.78 (SiC),
24.37 (CCC), 47.07 (NС), 119.67 q (CF3, J 319.0 Hz).
19F NMR spectrum: δF –74.48 ppm. 29Si NMR spec-
trum: δSi 8.38 ppm. Found, %: С 28.37; Н 5.21; F
22.06; N 5.11; S 12.31. C12H26F6N2O5S2Si2. Cal-
culated, %: С 28.13; Н 5.08; F 22.26; N 5.47; S 12.50.
Reaction of bis(3-chloropropyl)dimethyldisiloxane
III with triflamide. A mixture of siloxane III (0.085 g,
0.3 mmol), triflamide (0.088 g, 0.6 mmol) and triethyl-
amine (1.196 g, 1.2 mmol) was kept at room tem-
perature for 20 h. No changes occur according to NMR
data. The mixture was heated to 78–82°С for 8 h,
decomposed with water, extracted with ether, the
extract was dried over Na2SO41, the solvent removed in
a vacuum. According to the H, 13С, 29Si, 19F NMR
data, siloxane VI was formed in 90% yield.
ACKNOWLEDGMENTS
This work was performed with the financial support
from the Russian Foundation for Basic Research (grant
no. 11-03-91334).
4,4-Dimethyl-1-(trifluoromethylsulfonyl)-1,4-aza-
silepane (VII). Yield after chromatographic separation
16%, Rf 0.86. IR spectrum, ν, cm–1: 2954 (CH2), 1464
(SiC), 1386 (SO2), 1253 (SiMe), 1225 (CF3), 1183
(CF3), 1137 (SO2), 1067 (SN), 1018 (CN), 837 (CS),
The authors are thankful to T.N. Borodina (Irkutsk
Institute of Chemistry) for registration X-ray energy
dispersive spectra.
1
590 (CF3). Н NMR spectrum (343 K), δ, ppm: 0.10 s
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