Solvent interception, heterocyclization and desilylation upon NBS-induced sulfamidation of trimethyl(vinyl)silane

Article abstract of DOI:10.1039/c9ob01689a

The reaction of trimethyl(vinyl)silane with sulfonamides in the presence of N-bromosuccinimide was shown to proceed regioselectively in methylene chloride under mild conditions and led to the products of bromosulfamidation in up to 88% yield. The obtained adducts undergo base-promoted dehydrobromination to give 2-trimethylsilyl-N-sulfonyl aziridines in a close to quantitative yield. In the reaction with trifluoromethanesulfonamide in acetonitrile or tetrahydrofuran, the Ritter-type (solvent-interception) products were obtained and converted to 1-triflyl-2-methyl-5-(trimethylsilyl)-2-imidazoline or 4-triflyl-3-(trimethylsilyl)-1,4-oxazocane in almost quantitative yield.

Full text of DOI:10.1039/c9ob01689a

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21 December 2017
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Page 1 of 21
Organic & Biomolecular Chemistry
Solvent Interception, Heterocyclization and Desilylation upon NBS-induced
View Article Online
DOI: 10.1039/C9OB01689A
Sulfamidation of Trimethyl(vinyl)silane
Vera V. Astakhova, Mikhail Yu. Moskalik, Bagrat A. Shainyan*†
Graphical Abstract
Me3Si
Tf
98%
Me3Si
K2CO3
Br
NHSO2R
>97%
N
O
Br
O(CH2)4NHSO2R
R = CF3
NBS THF
t-BuOK
Me3Si
Me3Si
Me3Si
Me
NBS
MeCN
NBS
CH2Cl2
Br
HN
Br
NHSO2R
NTf
K2CO3
RSO2NH2
K2CO3
Me3Si
Me3Si
Tf
R = CF3, Me, Ar.
Tf = CF3SO2.
N
96%
N
95-99%
Me
SO2R
N
The reaction of trimethyl(vinyl)silane with sulfonamides in the presence of N-bromosuccinimide
was shown to proceed regioselectively in methylene chloride under mild conditions and led to
the products of bromosulfonamidation in up to 88% yield. The obtained adducts undergo base-
promoted dehydrobromination to give 2-trimethylsilyl-N-sulfonyl aziridines in a close to
quantitative yield. In the reaction with trifluoromethanesulfonamide in acetonitrile or
tetrahydrofuran, the Ritter-type (solvent-interception) products were obtained and converted to
1-triflyl-2-methyl-5-(trimethylsilyl)-2-imidazoline or 4-triflyl-3-(trimethylsilyl)-1,4-oxazocane
in almost quantitative yield.
Introduction
Haloamination of alkenes with sulfonamides and their derivatives is a simple and universal
method for the synthesis of polyfunctional adducts containing the amino group and a good
leaving group at the β-position to nitrogen. The use of dichloramines RSO2NX2 (X = Hlg) or
sulfonamides RSO2NH2 in the presence of external oxidants allows to perform haloamination of
various functionalized alkenes. Chloramines RSO2NXM (X = Cl, Br; M = Na, K) were also used
for haloamination of alkenes in good yields and high regio- and stereoselectivity under mild
conditions without additional catalysts.1
Dichloramines RSO2NX2 are effective reagents for haloamination of activated alkenes
(chalkones). Unlike reactions with chloramines RSO2NXNa, the latter reactions, as a rule,
proceed in the presence of metal salts as catalysts and do not require extra oxidants.2
Haloamination of alkenes can also be successfully realized by the use of sulfonamides and
an external oxidant as a source of electrophilic halogen. N-Halosuccinimides or mixed oxidative
systems on their basis proved to be efficient oxidants in such reactions. Thus, the reaction of 4-
*A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences
664033 Irkutsk, Russia. E-mail: bagrat@irioch.irk.ru.
† Electronic supplementary information (ESI) available: 1H and 13C NMR spectra of all new compounds (PDF). For
ESI see DOI:

Organic & Biomolecular Chemistry
Page 2 of 21
(trifluoromethyl)benzenesulfonamide as a nucleophile and N-bromosuccinimide (NBS) as a
View Article Online
DOI: 10.1039/C9OB01689A
source of halogen with nonactivated aliphatic and aromatic alkenes affords the products of
haloamination under mild conditions in the absence of catalysts; noteworthy, 4-substituted
styrenes give only α-amino adducts.3 The reaction of TsNH2 with the same substrates leads to
inversion of regioselectivity resulting exclusively in β-amino adducts.4 The reaction of α,β-
unsaturated carbonyl compounds with TsNH2 in the presence of N-halosuccinimides and
Sc(OTf)3 proceeds under mild conditions in a similar way, leading regio- and enantioselectively
to α-bromo-β-aminoketones.5 The method based on the use of (+)-tartaric acid as an
organocatalyst was successfully applied to α,β-unsaturated ketones and esters as well as simple
olefines.6 Among α,β-unsaturated carbonyl substrates, the derivatives with 4-anisyl group at the
double bond reacted highly regioselectively to form α-bromo-β-amino adducts, while other
substrates gave α-amino-β-bromo isomers.6 The same regioselectivity of aminobromination was
found when KI,7 silicon,8 copper powder,9 or FeCl210 were added to the mixture of NBS, TsNH2
and α,β-unsaturated carbonyl substrates.
In the presence of PhI(OAc)2, α,β-unsaturated carbonyl substrates with electron acceptor
substituents at the double bond in the presence of NBS and TsNH2 also give α-amino-β-bromo
adducts stereoselectively in good yields.1b The same products are formed under solvent-free
conditions with mechanoactivation.11 However, with styrene and 4-chlorostyrene under the same
conditions the main product was α-bromo-β-amino adduct.11 Similarly proceeds the reaction of
vinyl ketones or esters with NBS and TsNH2 in water in the presence of PhI(OAc)2.12 In the
presence of NBS and Ni(OAc)2, chalkones readily and stereoselectively react with N-
alkylsulfonamides to give α-amino-β-bromo adducts.13 At the same time, noncatalyzed reaction
of styrenes with TsNHMe and NBS leads almost quantitatively to α-bromo-β-amino
derivatives.14
2-Alkenylaziridines react with sulfonamides and NBS to give the corresponding
pyrrolidines, piperidines or azepanes.15 The reaction of alkenes with NBS and TsNH2 in the
presence of K2CO3, performed as a three-component process or in two steps, affords aziridines in
a close to quantitative yield.16 Carrying out the reaction of alkenes with NBS, NsNH2 and K2CO3
in the presence of epichlorohydrins leads to the corresponding morpholines.17
Oxidative addition of sulfonamides to alkenes or dienes in nitriles as solvents may proceed
with incorporation of the solvent molecule (Ritter reaction). Thus, sulfonamides enter the three-
component reaction with N-halosuccinimides to give haloamidines or imidazolidines, the yields
of the former being 24–26% for N-chloro- or N-iodosuccinimide, but up to 92% for NBS
(Scheme 1)18:

Page 3 of 21
Organic & Biomolecular Chemistry
X
CH3CN, 25oC
CH3
NTs
View Article Online
DOI: 10.1039/C9OB01689A
TsNH2
+
NXS
N
H
X = Cl, Br, I
Scheme 1. NBS-induced three-component reaction of sulfonamides with alkenes and nitriles.
In nitrile solutions in the presence of NBS, cyclohexene and TsNH2 also give amidines.18
At the same time, substituted cyclohexenes, 1-methylcyclohexadiene-1,4, 2-methylbutenes and
styrenes afford imidazolines as the products of intramolecular cyclization of the initially formed
amidines.18 The reaction of α,β-unsaturated carbonyl compounds with TsNH2 in the presence of
N-chlorosuccinimide leads to formation of CHCl2-imidazolidines (Scheme 2)19:
CHCl2
O
TsNH2, MeCN
NCS
Ts
N
N
R1
R2
R1
COR2
R1 = Ph, Me, 2-Ts; R2 = Me, Ar, OAlk.
Scheme 2. Side-chain chlorinated imidazolidines from TsNH2, enones and MeCN.
In THF solution, alkenes can also give the product of solvent molecule incorporation, δ-
aminoethers, when reacting with sulfonamides and NBS (Scheme 3)20:
R
TsNH2, NBS
0-25oC, THF
R1
R1
NHTs
R
O
Br
Scheme 3. THF-interception product via NBS-induced bromosulfamidation of alkenes.
In contrast to simple or electron-deficient alkenes, we were able to find only two examples
of oxidative addition of N-halosulfonamides to vinylsilanes as substrates. In an old work, the Cu-
catalyzed reaction of dichloramine T with vinyl and allyl(trimethyl)silanes was shown to give the
corresponding adducts with the sulfonamide group at the terminal carbon atom of the substrate.21
Under the action of K2CO3 the adduct to trimethyl(vinyl)silane underwent dehydrochlorination
to 1-tosyl-2-(trimethylsilyl)aziridine.21 Another example is the reaction of 4-silacyclopentenes
with chloramine T leading to 4-sila-6-azabicyclo[3.1.0]hexanes. The products suffer the aziridine
ring opening under the action of nucleophiles with N-deprotection and formation of Si-
containing cyclic β-aminoacids.22 Note also a Mn-based catalyst induced addition of PhI=NTs to
trimethylvinylsilane leading to 1-tosyl-2-(trimethylsilyl)aziridine in a low yield,23 and a specific
example of the synthesis of 2-isopropyl-1-tosyl-3-(trimethylsilyl)aziridine with 75% yield via
lithiation of 2-iodo-3-isopropyl-1-(tosyl)aziridine followed by the reaction with Me3SiCl.24

Organic & Biomolecular Chemistry
Page 4 of 21
Results and discussion
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Despite being very poorly studied, the reactions of oxidative sulfamidatDioOnI: 1o0.f10u39n/Cs9aOtuB0r1a6t8e9dA
silanes are of great potential interest. First, vinyl silanes must be active substrates because of
stabilizing effect of silicon on β-carbocations. Second, our very recent study of sulfamidation of
vinyl- and divinylsilanes in oxidative system (t-BuOCl + NaI)25 showed their diverse and
unexpected reactivity leading to numerous and sometimes unexpected products. Finally, the
products of these reactions are potentially bioactive as they contain pharmacophoric sulfonamide
group and silicon atom. Bioisosteric replacement is a promising approach to new drugs, and the
C and Si atoms are classical bioisosteres.
With this in mind and in continuation of our previous works on oxidative sulfamidation,25, 26
we report here the NBS-induced reactions of trimethyl(vinyl)silane 1 with various sulfonamides.
As follows from the aforesaid, the nature of the oxidant can drastically change the course of
sulfamidation and, as will be demonstrated below, these expectations were fully met. The
reactions turned out to be regioselective leading to the products of bromosulfonamidation and
their further transformations. First, we examined the reaction of compound 1 with tosylamide in
dichloromethane (DCM) in the presence of NBS and PhI(OAc)2 (Scheme 4, Table 1). The order
of mixing does not affect the total yield and ratio of the products. Note, that no reaction occurs in
the absence of NBS although the examples of oxidative sulfamidation the presence of PhI(OAc)2
as the only oxidant are known in the literature, see e.g.27
Me3Si
Br
Me3Si
Br
Oxidant
Me3Si
TsNH2
CH2Cl2, 20 h
Br
NHTs
3d
1
2
Scheme 4. Bromination vs. bromosulfamidation of trimethyl(vinyl)silane 1 with TsNH2 in the
presence of NBS in different oxidative conditions.
Table 1. Screening of the reaction conditions
Product yields, %
Entry 1 : TsNH2 Oxidant (TsNH2:oxidant) Temperature
2
3d
1
2
3
4
5
1:1
1:1
2:1
1:1
1:1
NBS (1:1)
25°С
25°С
25°С
25°С
40°С
7
88
–
95
49
52
46
NBS/PhI(OAc)2 (1:1:0.5)
NBS (1:1)
44
46
48
NBS (1:2)
NBS (1:1)
Based on the choice made in the first step, we performed the reactions of compound 1 with
a series of sulfonamides in the conditions shown in Scheme 5, Table 2:

Page 5 of 21
Organic & Biomolecular Chemistry
Me3Si
Br
NBS
Me3Si
View Article Online
DOI: 10.1039/C9OB01689A
2
RSO2NH2
CH2Cl2, rt, 20h
NHSO2R
3
R = CF3 (a), Me (b), Ph (c), Ts (d), p-MeOC6H4 (e),
p-ClC6H4 (f), p-BrC6H4 (g), p-NO2C6H4 (h).
Scheme 5. The reaction of compound 1 with sulfonamides in the presence of NBS.
Table 2. NBS-induced bromosulfonamidation of trimethyl(vinyl)silane 1
Product yields, %
Entry R in RSO2NH2
2
3
1
2
3
4
5
6
7
8
CF3
Me
5
85
23
13
7
48
81
88
72
74
79
76
Ph
Ts
p-MeOC6H4
p-ClC6H4
p-BrC6H4
p-NO2C6H4
14
10
11
10
1:RSO2NH2:NBS 1:1:1
The results in Table 2 clearly show that, except with methanesulfonamide, the yields with
all other sulfonamides are rather high, so, the reaction can serve as a preparative method for the
synthesis of β-silylated sulfonamides capable of further functionalization owing to the presence
of readily removable bromine atom. The structure of the bromosulfamidation products 3 (and,
hence, the regioselectivity of the reaction) was determined from the multiplicity of the NH signal
1
in their H NMR spectra, which appears as a doublet of doublets due to splitting on two
diastereotopic methylene protons. Therefore, bromoamidation in Scheme 5 is regioselective,
with the bromine atom adding to the α-position to the Me3Si group, and the sulfonamide residue
– to the terminal carbon atom. Such a regioselectivity is opposite to that observed by us earlier in
oxidative haloamidation of non-silylated substrates with sulfonamides in the system (t-BuOCl +
NaI)29 and, apparently, is due to strong electron-donating effect of the silyl group. Note, that
formation of α-amino-β-halo adducts was referred to as ‘normal regioselectivity’, while the
formation of their β-amino-α-halo isomers – ‘opposite regioselectivity’.4
Noteworthy, the reaction of compound 1 with 4-aminobenzenesulfonamide (sulfanilamide)
under the same conditions gives no products of aminobromination; instead, only the product of

Organic & Biomolecular Chemistry
Page 6 of 21
electrophilic bromination of electron-rich aromatic ring of sulfanilamide – 4-amino-3-
View Article Online
DOI: 10.1039/C9OB01689A
bromobenzenesulfonamide – was isolated.
Motivated by the literature data28 on the formation of N-tosylaziridines in up to 88% yield in
the reaction of alkenes with tosylamide in the presence of PhI(OAc)2, I2 and a base, we tried the
reaction of 1 with trifluoromethanesulfonamide (triflamide) in dichloroethane using the system
PhI(OAc)2/I2/K2CO3. Three products, similar to those in28, were isolated, but, unlike the reaction
of styrene with tosylamide28, the yield of aziridine 6 was as low as 3% (vs. 72% in28) (Scheme 6):
Me3Si
Me3Si
Me3Si
I
PhI(OAc)2/I2, K2CO3
ClCH2-CH2Cl, rt
Me3Si
TfNH2
N
OAc
I
NHTf
5
(20%)
Tf
(3%)
4
(63%)
6
Scheme 6. Oxidative addition products in the reaction of trimethyl(vinyl)silane 1 with TfNH2.
Although compound 6 is a very minor product, its formation is noteworthy because, in
contrast to similar 1-arylsulfonyl-2-silylaziridines, it could not be obtained neither by the
reaction of silane 1 with triflamide in the system (t-BuOCl + NaI)25, nor by dehydrobromination
of 3a (vide infra, see Scheme 9 below).
The structure of the product of iodotriflamidation 4 was proved by the splitting pattern of
the NH signal (vide supra) represented by a triplet due to very close coupling constants on the
two methylene protons.
Remarkably, changing the solvent from DCM to nitriles in order to check the possibility of
formation of the Ritter-type products gave unexpected results. When carrying out the reaction of
compound 1 with various sulfonamides in the presence of NBS in acetonitrile, isobutyronitrile
and benzonitrile as solvents (Table 3), only with triflamide in MeCN the Ritter-type product, N-
[2-bromo-2-(trimethylsilyl)ethyl]-N'-(triflyl)ethanimidamide 7, was formed in >80% yield. With
triflamide in the solutions in other nitriles, or with other sulfonamides in acetonitrile, no
amidines were formed, only the product of bromination 2 and the products of
bromosulfamidation 3 were obtained (Scheme 7):
Me3Si
Br
NBS
R'CN, rt, 20h
Me3Si
R'
NSO2R
3
2
RSO2NH2
HN
7
R = CF3 (a), Me (b), Ts (d), p-NO2C6H4 (h); R' = Me, i-Pr, Ph.
Scheme 7. NBS-induced reaction of silane 1 with sulfonamides in nitrile solutions.
Specific behavior of triflamide with respect to other sulfonamides is clearly seen from
Table 3 and is another manifestation of its unique reactivity (for other examples, see review30).

Page 7 of 21
Organic & Biomolecular Chemistry
Table 3. Yields of products of the reaction of compound 1 with sulfonamides in nitrile solutions
View Article Online
DOI: 10.1039/C9OB01689A
Yield, %
Entry R in RSO2NH2 R' in R'C≡N
2
3
7
1
2
3
4
5
Me
Ph
4
10
81
CF3
56
37
62
34
12
40
31
46
26
58
74
48
-
-
-
-
-
-
i-Pr
Me
Me
Me
i-Pr
Me
Ts
6
p-NO2C6H4
1:RSO2NH2:NBS 1:1:1
Two reasons can be invoked to explain the observed reactivity. First is the difference in
nucleophilicity between the sulfonamide and acetonitrile with respect to the attack of cationoid
species [Me3SiCH(Br)CH+]. The reaction with sulfonamide gives rise to adduct 3, whereas the
attack by acetonitrile molecule leads to amidine 7. Evidently, very low nucleophilicity of
triflamide as compared to other sulfonamides favors the latter process (Ritter reaction). Second,
the above cationic species in solution can form a contact ion pair with sulfonamide; with
triflamide, the nucleophile–electrophile interaction is the weakest and the electrophile is most
open to the reaction with acetonitrile.
Similarly, when carrying out the reaction of 1 with sulfonamides in the same conditions
but in THF as solvent, the latter acts as an O-nucleophile leading after the THF ring opening to
solvent-interception products N-(4-[2-bromo-2-(trimethylsilyl)ethoxy]butyl)sulfonamides 8 and
[1-bromo-2-(4-bromobutoxy)ethyl] (trimethyl)silane 9 (Scheme 8, Table 4). Similar solvent-
interception products with δ-aminoether motif similar to that in compound 8 were obtained by
the reaction of styrenes with TsNBr2 in THF,31 but, again, the regioselectivity of the reactions
with silane 1 was opposite to that with styrenes.
Me3Si
Br
Me3Si
Br
NBS
Me3Si
2
RSO2NH2
THF, rt, 20h
O(CH2)4NHSO2R
O(CH2)4Br
R = CF3 (a), Me (b), Ts (d), p-NO2C6H4 (h).
8
9
Scheme 8. NBS-induced reaction of trimethyl(vinyl)silane 1 with sulfonamides in THF
Table 4. Yields of the products of oxidative addition of sulfonamides to trimethyl(vinyl)silane 1
in THF
Entry R in RSO2NH2
Yield, %

Organic & Biomolecular Chemistry
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2
8
9
View Article Online
1
2
3
4
CF3
Me
5
7
56
–
29
70
24
–
DOI: 10.1039/C9OB01689A
Ts
9
55
77
p-NO2C6H4
11
1:RSO2NH2:NBS 1:1:1
The products of sulfonamidation 3 were subjected to base-induced elimination using
different bases. For R = Ar, the reaction leads to N-sulfonyl-2-trimethylsilylaziridines 10 in
almost quantitative yield (Scheme 9, Table 5).
Me3Si
Me3Si
Br
t-BuO
Me3SiOBu-t
Base
Br
NHSO2R
N
NHSO2R
SO2R
10
3
11
R = CF3 (a), Me (b), Ph (c), Ts (d), p-MeOC6H4 (e),
p-ClC6H4 (f), p-BrC6H4 (g), p-NO2C6H4 (h).
Base = Et3N or K2CO3.
Scheme 9. Aziridination vs. desilylation in the base-induced elimination from adducts 3.
Table 5. Yields of the products of base-induced elimination from adducts 3
Et3N (1:3)
CH2Cl2, 2 h,
0°C
Et3N (1:3)
CH2Cl2, 15 h,
rt
t-BuOK (1:1), K2CO3 (1:2),
THF, 2–3 h,
rt
MeCN, 7 h,
rt
R in
Entry
RSO2NH2
10
–
10
–
11
–
10
–
1
2
3
4
5
6
7
8
CF3
CH3
–
95
–
–
95
97
99
98
98
97
96
Ph
–
97
98
–
Ts
9
90
–
p-MeOC6H4
p-ClC6H4
p-BrC6H4
p-NO2C6H4
–
–
–
–
97
99
98
98
–
–
–
Note, that products 10c, 10d, 10f, 10h have been recently obtained by us by oxidative
sulfonamidation of silane 1 with the corresponding arenesulfonamides in the system (t-BuOCl +
NaI), although in somewhat lower yield (73–91%).25 Remarkably, the reaction was carried in

Page 9 of 21
Organic & Biomolecular Chemistry
MeCN, as in Scheme 7, but no products of solvent interception similar to amidines 7 were
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DOI: 10.1039/C9OB01689A
formed.
No products could be isolated from the reaction of compound 3a (R = CF3) with neither of
the studied bases. Triethylamine was active only in the reaction with 3d, the yield of aziridine
10d increasing from 9 to 90% in going from 2 h reaction time at 0°C to 15 h at room
temperature. With a strong base t-BuOK, compounds 3b and 3e–h give N-sulfonyl-2-
trimethylsilylaziridines 10b and 10e–h, whereas 3c and 3d unexpectedly afford the products of
desilylation 11c,d. The formation of 2-bromoethylarenesulfonamides 11c,d is, apparently, the
result of nucleophilic attack of t-BuO– on the highly oxophilic silicon atom leading to t-
butoxy(trimethyl)silane Me3SiOBu-t 12 and carbanion [RSO2NHCH2CHBr]–, which finally
captures a proton to form products 11c,d. Desilylation in Scheme 9, which has no analogy in the
reactions of the products of bromoamination of alkenes5–10 clearly demonstrates the principal
difference between vinyl silanes and alkenes. It is still not clear why desilylation occurs
specifically with adducts 3c,d but not with other products of sulfonamidation 3. Products 10 and
11 were obtained selectively in a close to quantitative yield. Most selective is the reaction with
potassium carbonate occurring, again, in a close to quantitative yield with all products of
bromosulfamidation 3 (except 3a).
Although the triflamide-based compound 3a does not react with bases under the conditions
given in Table 5, the one-pot reaction of triflamide with trimethyl(vinyl)silane 1 in the presence
of NBS in acetonitrile and with subsequent addition of K2CO3 gave imidazoline 13 (Scheme 10).
Me3Si
i: NBS, MeCN
rt, 5-8 h
Me3Si
CF3SO2NH2
N
N
ii: K2CO3
CF3SO2
Me
13
Me3Si
Br
Me3Si
Br
K2CO3 (2 equiv.)
MeCN, rt, 15 h
Me
NSO2CF3
R'
NSO2CF3
HN
N
7a
Scheme 10. Formation of imidazoline 13 in one-pot reaction of triflamide with silane 1 in the
presence of NBS in acetonitrile and by dehydrobromination of amidine 7a with K2CO3.
Imidazoline 13 was also obtained in almost quantitative yield by dehydrobromination of 7a
(prepared as shown in Scheme 7) with potassium carbonate. Remarkably, dehydrobromination
proceeds not as 1,3-elimination, that would lead to aziridine, but as 1,5-elimination as shown in
Scheme 10, due to preferable localization of the negative charge on the sulfonamide nitrogen
atom bearing strongly electron acceptor triflyl group.

Organic & Biomolecular Chemistry
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The THF-interception product 8a under the same conditions is also dehydrobrominated to
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DOI: 10.1039/C9OB01689A
N-triflyl-3-(trimethylsilyl)-1,4-oxazocane 14 in >98% yield (Scheme 11).
Me3Si
K2CO3 (2 equiv.)
CF3SO2
N
O
Br
O(CH2)4NHSO2CF3
5 ml MeCN, rt, 15h
Me3Si
8a
14
Scheme 11. Dehydrobromination of 8a with potassium carbonate.
In contrast, no reaction occurred under the same reaction conditions with arenesulfonamide
derivatives 8d or 8h, perhaps, due to higher acidity of 8a facilitating its deprotonation and
further intramolecular nucleophilic substitution of bromine leading to the product of cyclization.
Conclusions
N-Bromosuccinimide-induced reactions of trimethyl(vinyl)silane
1
with various
sulfonamides were found to be strongly solvent and reagent dependent. In dichloromethane, the
products of bromosulfamidation are formed in up to 88% yield, the dibromo adduct
Me3SiCHBrCH2Br being the minor one. The products of bromosulfamidation either cyclize,
almost quantitatively, to N-sulfonyl-2-trimethylsilylaziridines with soft base K2CO3, or, under
the action of a strong base t-BuOK, may undergo desilylation to give t-butoxy(trimethyl)silane
due to high oxophilicity of silicon. In acetonitrile, methanesulfonamide and arenesulfonamides
react with formation of comparable amounts of the products of bromosulfamidation and
dibromination, whereas triflamide gives exclusively the Ritter-type product with incorporation of
acetonitrile fragment, amidine Me3SiCHBrCH2NHC(Me)=NSO2CF3, in 81% yield. The latter,
under the action of K2CO3 is completely converted to the corresponding imidazoline via 1,5-
elimination of HBr. In THF solution, two Ritter-type products with incorporation of –O(CH2)4–
unit into the molecule of the dibromo adduct or of the product of bromosulfamidation are formed
in good overall yield. The Ritter-type product of bromotriflamidation with participation of THF
undergoes 1,8-elimination of HBr to give N-triflyl-3-(trimethylsilyl)-1,4-oxazocane.
The performed study, on the one hand, has demonstrated a diversity of patterns of reactivity
of sulfonamides in reactions with vinyl silanes on the example of its simplest representative,
which is different from that of the recently studied sulfamidation in another oxidative system.25
On the other hand, this study provides efficient and, in some cases, almost quantitative methods
for the synthesis of otherwise not easily accessible heterocycles and polyfunctional organosilicon
compounds.
Experimental

Page 11 of 21
Organic & Biomolecular Chemistry
General information
View Article Online
DOI: 10.1039/C9OB01689A
1
13
19
29
Commercial starting materials were used. All products were identified by H, C, F and Si
NMR spectroscopy. IR spectra were taken on a Bruker Vertex 70 spectrophotometer in thin
layer. NMR spectra were registered on a Bruker DPX 400 spectrometer at working frequencies
400 (1H), 100 (13C), 376 (19F) and 79.5 (29Si) MHz. Chemical shifts are reported in parts per
1
million (ppm) relative to residual CHCl3 and CDCl3 peaks (7.27 and 77.1 ppm, H and 13C
NMR, respectively). All coupling constants (J) are reported in hertz (Hz). Abbreviations are: s,
singlet; d, doublet; t, triplet; q, quartet. Melting points were measured on MeltEMP (laboratory
devices). All flash chromatography was performed using silica gel, 60 Å, 300 mesh. TLC
analysis was carried out on aluminum plates coated with silica gel 60 F254, 0.2 mm thickness.
The plates were visualized using a 254 nm ultraviolet lamp or aqueous NaIO4 solutions. All
NMR spectra are given in the Supporting Information.
Synthesis and characterization of compounds
Reaction of tosylamide with trimethyl(vinyl)silane in different oxidative systems.
Optimization of reaction conditions. PhI(OAc)2. To the solution of 1.00 g (5.8 mmol) of
tosylamide and 1.88 g (5.8 mmol) PhI(OAc)2 in 60 ml CH2Cl2 0.85 ml (5.8 mmol) of
trimethyl(vinyl)silane 1 was added and the mixture kept for 20 h at room temperature. After
completion, CH2Cl2 was removed at a reduced pressure, the residue (2.56 g) charged in the
column with coarse silica and eluted successively with hexane, hexane–ether 1:1, ether.
Unreacted tosylamide, iodobenzene and acetic acid were isolated.
N-Bromosuccinimide. To the solution of 1.00 g (5.8 mmol) of tosylamide and 1.04 g (5.8
mmol) of NBS in 60 ml of CH2Cl2 0.85 ml (5.8 mmol) of trimethyl(vinyl)silane 1 was added and
the mixture kept for 20 h at room temperature. After completion, CH2Cl2 was removed in
vacuum, the residue (2.86 g) dissolved in 70 ml of ether, N-succinimide was filtered off, the
filtrate evaporated, the residue (2.45 g) separated on a silica column with hexane and hexane–
ether 1:1 as eluents. From hexane eluate, 0.11 g (7%) of (1,2-dibromoethyl)trimethylsilane 2 was
isolated as colorless liquid, and from hexane–ether eluate 1.80 g (88%) of white crystals of N-(2-
bromo-2-(trimethylsilyl)ethyl)tosylamide 3d was obtained.
With other molar ratios 1:NBS:TsNH2, the reaction was carried out and treated similarly;
the yields of products 2 and 3d are given in Table 1.
PhI(OAc)2+NBS. To the solution of 1.00 g (5.8 mmol) of tosylamide, 1.04 g (5.8 mmol)
of NBS and 0.94 g (2.9 mmol) of PhI(OAc)2 in 60 ml CH2Cl2 0.85 ml (5.8 mmol) of
trimethyl(vinyl)silane was added, the mixture kept for 20 h at room temperature and treated as
above. The residue (3.49 g) was separated by column chromatography eluting successively with

Organic & Biomolecular Chemistry
Page 12 of 21
hexane and hexane–ether 1:1. From the hexane eluate, 0.36 g of iodobenzene was isolated as
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DOI: 10.1039/C9OB01689A
colorless liquid, and from hexane–ether eluate 1.94 g (95%) of 3d was obtained as white solid,
identical to that above.
Reaction of triflamide with trimethyl(vinyl)silane 1 in dichloroethane in the presence
of PhI(OAc)2/I2/K2CO3. To the solution of 2.01 g (14 mmol) of triflamide in 80 ml of
dichloroethane was added 3.86 g (28 mmol) of K2CO3, then after 10 min 4.83 g (15 mmol) of
PhI(OAc)2 was introduced and the mixture was stirred at room temperature for 1 h. After that,
1.45 ml (10 mmol) of trimethyl(vinyl)silane 1 and 1.27 g (5 mmol) I2 was added, the insoluble
substances filtered off, the solvent removed on a rotary evaporator, the residue (3.67 g) separated
by column chromatography eluting successively with hexane and hexane–ether 1:1. From the
hexane extract 0.60 g of iodobenzene was obtained, and from hexane–ether part – 1.55 g (63%)
of 2-iodo-2-(trimethylsilyl)ethyl acetate
4
and 0.73
g
(20%) of N-(2-iodo-2-
(trimethylsilyl)ethyl)triflamide 5 as light-yellow liquids.
Reaction of sulfonamides with trimethyl(vinyl)silane 1 in the presence of NBS in
CH2Cl2. General procedure. To the solution of sulfonamide and NBS in 70 ml of CH2Cl2
trimethyl(vinyl)silane 1 was added, the mixture kept for 20 h at room temperature. After
completion, CH2Cl2 was removed at a reduced pressure, the residue dissolved in 70 ml of ether,
N-succinimide filtered off, filtrate evaporated, the residue separated by column chromatography
eluting successively with hexane and hexane–ether 1:1. From the hexane part compound 2 was
isolated, from hexane–ether extract – the corresponding N-(2-bromo-2-(trimethylsilyl)ethyl)-
sulfonamide 3 was obtained as an oil or white solid. The yields are given in Table 2.
Reaction of sulfonamides with trimethyl(vinyl)silane 1 in the presence of NBS in
MeCN, i-PrCN or PhCN solution. General procedure. To the solution of sulfonamide and
NBS in 70 ml of MeCN, i-PrCN or PhCN trimethyl(vinyl)silane 1 was added, the mixture kept
for 20 h at room temperature. After the reaction was completed, the solvent was removed at a
reduced pressure, the residue dissolved in 70 ml of ether, N-succinimide filtered off, the filtrate
evaporated. The residue was treated by column chromatography successively with hexane,
hexane–ether 1:1, ether as eluents. From the hexane extract, compound 2 was isolated, from
hexane–ether eluate – the corresponding compound 3, and from ether – amidine 7.
Reaction of sulfonamides with trimethyl(vinyl)silane 1 in the presence of NBS in THF.
General procedure. To the solution of sulfonamide and NBS in 70 ml of THF
trimethyl(vinyl)silane 1 was added, the mixture was kept for 20 h at room temperature. After
completion of the reaction, THF was removed at a reduced pressure, the residue dissolved in 70
ml of ether, N-succinimide was filtered off, the filtrate concentrated, the residue separated by
column chromatography eluting successively with hexane and hexane–ether 1:1. From hexane

Page 13 of 21
Organic & Biomolecular Chemistry
eluate, compound 2 and (1-bromo-2-(4-bromobutoxy)ethyl)trimethylsilane 9 were obtained as
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DOI: 10.1039/C9OB01689A
colorless liquids, from hexane–ether – N-(4-(2-bromo-2-(trimethyl)ethoxy)butyl)sulfonamides
8a, 8d, 8h were isolated as yellow oils crystallized upon long standing.
Reaction of N-(2-bromo-2-(trimethylsilyl)ethyl)sulfonamides with K2CO3 in MeCN.
To the solution of (0.37–0.55 mmol) of N-(2-bromo-2-(trimethylsilyl)ethyl)sulfonamides 3 in 5
ml of MeCN, double molar excess of K2CO3 was added, the mixture was stirred for 7 h at room
temperature. After completion of the reaction, the mixture was filtered, solvent removed, the
residue dried in vacuum to obtain the corresponding N-sulfonyl-2-(trimethylsilyl)aziridines 10 in
95–99% yield (see Table 5), except for the reaction with triflamide 3a derivative, which gave
only the products of resinification.
Reaction of N-(2-bromo-2-(trimethylsilyl)ethyl)tosylamide 3d with Et3N in CH2Cl2.
To the solution of 0.140 g (0.40 mmol) of compound 3d in 5 ml of CH2Cl2, 0.17 ml (1.2 mmol)
of Et3N was added, the obtained mixture was stirred for 2 h at 0°С. After completion of the
reaction the solvent was removed on a rotary evaporator, the residue dried in vacuum to obtain
0.010 g (9%) of aziridine 10d. The increase of the reaction time to 15 h and the temperature from
0°С to room temperature allowed to obtain product 10d in 90% yield.
Reaction of N-(2-bromo-2-(trimethylsilyl)ethyl)arenesulfonamides 3 with t-BuOK in
THF. To the solution of (0.4–0.5 mmol) of N-(2-bromo-2-(trimethylsilyl)ethyl)sulfonamide 3c
or 3d in 5 ml of THF the equimolar amount of t-BuOK was added, the mixture stirred for 3 h at
room temperature. After completion of the reaction the mixture was passed through the column
with coarse silica to remove residual t-BuOK and insoluble admixtures. Then the solvent was
removed on a rotary evaporator and the residue dried in vacuum to obtain N-(2-
bromoethyl)benzenesulfonamides 11c or 11d in a high yield (see Table 5).
The similarly performed reaction of other N-(2-bromo-2-(trimethylsilyl)ethyl))sulfonamides
3b, e–h with t-BuOK afforded the corresponding N-sulfonyl-2-(trimethylsilyl)aziridine 10 in
nearly quantitative yield (see Table 5). With the triflamide derivative 3a, however, only the
products of resinification were formed.
Reaction of N-(2-bromo-2-(trimethylsilyl)ethyl)-N'-(triflyl)acetamidine 7a with K2CO3
in MeCN. To the solution of 0.150 g (0.41 mmol) N-(2-bromo-2-(trimethylsilyl)ethyl)-N'-
(triflyl)acetamidine 7a in 5 ml of MeCN 0.112 g (0.81 mmol) K2CO3 was added, the obtained
mixture stirred for 15 h at room temperature. After completion, the formed precipitate was
filtered, solvent removed on a rotary evaporator. The residue was dried in vacuum to give 0.112
g (96%) of 2-methyl-1-(triflyl)-5-(trimethylsilyl)-4,5-dihydro-1H-imidazole 13.
Reaction of N-(4-(2-bromo-2-(trimethylsilyl)ethoxy)butyl)sulfonamide 8a with K2CO3
in MeCN. To the solution of 0.140
g
(0.35 mmol) of N-(4-(2-bromo-2-

Organic & Biomolecular Chemistry
Page 14 of 21
(trimethylsilyl)ethoxy)butyl)triflamide 8a in 5 ml MeCN, two-fold excess of K2CO3 was added,
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DOI: 10.1039/C9OB01689A
the mixture stirred for 15 h at room temperature. After the reaction was completed, the formed
precipitate was filtered off, the solvent removed on a rotary evaporator and the residue dried in
vacuum to give 0.110 g (98.6%) of N-triflyl-3-(trimethylsilyl)-1,4-oxazocane 14.
Reactions with 8d and 8h were performed similarly, but the 1H NMR spectra of the crude
products after removal of solvent showed the presence of only the signals of unreacted N-(4-(2-
bromo-2-(trimethylsilyl)ethoxy)butyl)sulfonamides 8d or 8h and no traces of the corresponding
1,4-oxazocanes.
(1,2-Dibromoethyl)trimethylsilane, 2. Oil. Yields see in Table 1. IR: 2955, 2900, 1516,
1415, 1254, 1121, 1099, 1027, 845, 759, 705, 630, 596, 535 cm–1. 1H NMR: δ 3.98 (dd, CHH, J
10.9, 4.5 Hz, 1H), 3.72 (dd, CHH, J 10.9, 10.4 Hz, 1H), 3.49 (dd, CH, J 10.4, 4.5 Hz, 1H), 0.22
(s, CH3, 9H). 13C NMR: δ 43.0 (CH2Br), 36.6 (CHBr), -2.4 (CH3). 29Si NMR: δ 5.02. Anal. calcd
for C5H12Br2Si: C, 23.09; H, 4.65; Br, 61.45; Si, 10.80. Found: C, 23.01; H, 4.59; Br, 60.98; Si,
10.74.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-1,1,1-trifluoromethanesulfonamide, 3a. Yellow
oil. Yield 85%. IR: 3309, 2960, 1741, 1546, 1428, 1374, 1231, 1196, 1146, 1074, 1026, 967,
848, 760, 722, 612, 479 cm-1. 1H NMR: δ 5.53 (dd, NH, J 6.4, 3.1 Hz, 1H), 3.78 (ddd, CHBN, J
14.3, 6.4, 2.6 Hz, 1H), 3.48 (ddd, CHAN, J 14.3, 11.1, 3.1 Hz, 1H), 3.34 (dd, CHBr, J 11.1, 2.6
Hz, 1H), 0.19 (s, 3CH3, 9H). 13C NMR: δ 119.2 (q, CF3, J 321.4 Hz), 47.7 (CH2N), 42.6 (CHBr),
19
29
-3.1 (CH3). F NMR: δ –77.2. Si NMR: δ 4.17. Anal. calcd for C6H13BrF3NO2SSi: C, 21.96;
H, 3.99; N, 4.27; F, 17.36; Br, 24.34; S, 9.77; Si, 8.56. Found: C, 21.91; H, 3.85; N, 4.22; F,
17.00; Br, 24.10; S, 9.67; Si, 8.49.
N-(2-Bromo-2-(trimethylsilyl)ethyl)methanesulfonamide, 3b. White solid. Mp 82 °C.
Yield 48%. IR: 3304, 3025, 2962, 1732, 1521, 1409, 1311, 1252, 1172, 1145, 1083, 1024, 980,
844, 757, 698, 618, 518 cm–1. 1H NMR: δ 5.08 (br. s, NH, 1H), 3.63 (ddd, CHBN, J 12.9, 7.0, 1.6
Hz), 3.38 (dd, CHBr, J 10.6, 1.6 Hz, 1H), 3.31 (ddd, CHAN, J 12.9, 10.6, 4.2 Hz, 1H), 3.01 (s,
CH3, 3H), 0.20 (s, CH3, 9H). 13C NMR: δ 46.6 (CH2N), 43.2 (CHBr), 41.0 (CH3SO2), -2.85
(CH3); 29Si NMR: δ 5.02. Anal. calcd for C6H16BrNO2SSi: C, 26.28; H, 5.88; N, 5.11; Br, 29.14;
S, 11.69; Si, 10.24.Found C, 26.21; H, 5.75; N, 5.03; Br, 29.00; S, 11.59; Si, 10.18.
N-(2-Bromo-2-(trimethylsilyl)ethyl)benzenesulfonamide, 3c. Oil. Yield 81%. IR: 3283,
3065, 2957, 2904, 2867, 1445, 1413, 1327, 1253, 1162, 1090, 1020, 845, 755, 726, 691, 586,
501 cm–1. 1H NMR: δ 7.88 (d, o-CH, J 7.8 Hz, 2H), 7.61 (t, p-CH, J 7.8 Hz, 1H), 7.54 (t, m-CH,
J 7.8 Hz, 2H), 5.01 (br. dd, NH, J 7.2, 3.4 Hz, 1H), 3.49 (ddd, CHBN, J 12.5, 7.2, 1.6 Hz), 3.23
(dd, CHBr, J 10.5, 1.6 Hz, 1H), 3.17 (ddd, CHAN, J 12.5, 10.5, 3.4 Hz, 1H), 0.12 (s, CH3, 9H).
13C NMR: δ 139.9 (Ci), 132.9 (Cp), 129.2 (Co), 127.0 (Cm), 46.4 (CH2N), 42.6 (CHBr), -2.9

Page 15 of 21
Organic & Biomolecular Chemistry
(CH3); 29Si NMR: δ 5.01. Anal. calcd for C11H18BrNO2SSi: C, 39.28; H, 5.39; N, 4.16; Br,
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DOI: 10.1039/C9OB01689A
23.76; S, 9.53; Si, 8.35. Found: %: C, 39.20; H, 5.33; N, 4.09; Br, 23.52; S, 9.48; Si, 8.28.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-4-methylbenzenesulfonamide, 3d. White solid. Mp
86 °C. Yields see in Table 1. IR: 3284, 2956, 2926, 2863, 1735, 1644, 1598, 1516, 1413, 1329,
1253, 1160, 1089, 1019, 968, 845, 758, 666, 552, 504 cm–1. 1H NMR: δ 7.75 (d, o-CH, J 8.2 Hz,
2H), 7.33 (d, m-CH, J 8.2 Hz, 2H), 4.95 (br. dd, NH, J 8.0, 3.9 Hz, 1H), 3.47 (ddd, CHBN, J
13.3, 8.0, 2.4 Hz), 3.24 (dd, CHBr, J 10.3, 2.4 Hz, 1H), 3.15 (ddd, CHAN, J 13.3, 10.3, 3.9 Hz,
13
1H), 2.44 (s, CH3Ph, 3H), 0.12 (s, CH3, 9H). C NMR: δ 143.6 (Cp), 136.8 (Ci), 129.8 (Cm),
127.0 (Co), 46.3 (CH2N), 42.7(CHBr), 21.5 (CH3Ph), -2.9 (CH3); 29Si NMR: δ 4.99. HRMS
(ESI): m/z: [M+H]+ calcd for C12H21BrNO2SSi: 350.0246; found: 350.0254; Anal. calcd for
C12H20BrNO2SSi: C, 41.14; H, 5.75; N, 4.00; Br, 22.81; S, 9.15; Si, 8.02. Found: C, 41.10; H,
5.68; N, 3.88; Br, 20.96; S, 9.02; Si, 7.79.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-4-methoxybenzenesulfonamide, 3e. White solid.
Mp 106 °C. Yield 72%. IR: 3279, 2955, 2847, 1739, 1596, 1499, 1453, 1412, 1328, 1257, 1155,
1091, 1024, 840, 757, 673, 560 cm–1. 1H NMR: δ 7.80 (d, o-CH, J 8.9 Hz, 2H), 7.00 (d, m-CH, J
8.9 Hz, 2H), 4.89 (br. dd, NH, J 7.6, 3.9 Hz, 1H), 3.88 (s, CH3O, 3H), 3.46 (ddd, CHBN, J 13.5,
7.6, 2.6 Hz), 3.25 (dd, CHBr, J 10.3, 2.6 Hz, 1H), 3.15 (ddd, CHAN, J 13.5, 10.3, 3.9 Hz, 1H),
0.13 (s, CH3, 9H). 13C NMR: δ 163.0 (Cp), 131.4 (Ci), 129.2 (Co), 114.4 (Cm), 55.7 (MeO), 46.4
(CH2N), 42.6 (CHBr), -2.9 (CH3); 29Si NMR: δ 5.00. Anal. calcd for C12H20BrNO3SSi: C, 39.34;
H, 5.50; N, 3.82; Br, 21.81; S, 8.75; Si, 7.67. Found: C, 39.32; H, 5.46; N, 3.80; Br, 21.63; S,
8.67; Si, 7.61.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-4-chlorobenzenesulfonamide, 3f. White solid. Mp
105 °C. Yield 74%. IR: 3282, 3092, 2957, 2906, 1582, 1475, 1409, 1332, 1254, 1163, 1089,
1013, 966, 844, 755, 702, 625, 569, 482 cm–1. 1H NMR: δ 7.82 (d, o-CH, J 8.5 Hz, 2H), 7.51 (d,
m-CH, J 8.5 Hz, 2H), 5.08 (br. dd, NH, J 7.1, 4.0 Hz, 1H), 3.49 (ddd, CHBN, J 13.4, 7.6, 2.5 Hz),
3.26 (dd, CHBr, J 10.3, 2.5 Hz, 1H), 3.17 (ddd, CHAN, J 13.4, 10.3, 4.0 Hz, 1H), 0.14 (s, CH3,
9H). 13C NMR: δ 139.3 (Ci), 138.5 (Cp), 129.5 (Cm), 128.5 (Co), 46.4 (CH2N), 42.4 (CHBr), -2.9
29
(CH3). Si NMR: δ 5.03. Anal. calcd for C11H17BrClNO2SSi: C, 35.63; H, 4.62; N, 3.78; Br,
21.55; Cl, 9.56; S, 8.65; Si, 7.57. Found: C, 35.61; H, 4.60; N, 3.77; Br, 21.47; Cl, 9.45; S, 8.59;
Si, 7.51.
4-Bromo-N-(2-bromo-2-(trimethylsilyl)ethyl)benzenesulfonamide, 3g. White solid. Mp
85 °C. Yield 79%. IR: 3284, 3090, 2956, 1574, 1469, 1414, 1332, 1254, 1163, 1087, 1009, 964,
846, 741, 701, 612, 568, 505, 418 cm–1. 1H NMR: δ 7.74 (d, o-CH, J 8.2 Hz, 2H), 7.68 (d, m-CH,
J 8.2 Hz, 2H), 5.00 (br. dd, NH, J 7.1, 3.9 Hz, 1H), 3.49 (ddd, CHBN, J 13.4, 7.1, 2.5 Hz), 3.26
(dd, CHBr, J 10.3, 2.5 Hz, 1H), 3.17 (ddd, CHAN, J 13.4, 10.3, 3.9 Hz, 1H), 0.15 (s, CH3, 9H).

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13C NMR: δ 139.0 (Ci), 132.5 (Cm), 128.6 (Co), 127.8 (Cp), 46.4 (CH2N), 42.4 (CHBr), -2.9
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29
DOI: 10.1039/C9OB01689A
(CH3); Si NMR: δ 5.03. Anal. calcd for C11H17Br2NO2SSi: C, 31.82; H, 4.13; N, 3.37; Br,
38.49; S, 7.72; Si, 6.76. Found: C, 31.79; H, 4.11; N, 3.35; Br, 38.22; S, 7.64; Si, 6.66.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-4-nitrobenzenesulfonamide, 3h. White solid. Mp
162 °C. Yield 76%. IR: 3284, 3113, 2957, 1607, 1528, 1415, 1346, 1311, 1252, 1167, 1088,
1014, 846, 736, 689, 613, 568, 523, 460 cm–1. 1H NMR: δ 8.39 (d, m-CH, J 8.7 Hz, 2H), 8.07 (d,
o-CH, J 8.2 Hz, 2H), 5.17 (br. dd, NH, J 7.4, 3.6 Hz, 1H), 3.57 (ddd, CHBN, J 12.8, 7.4, 1.6 Hz),
3.27 (dd, CHBr, J 10.7, 1.6 Hz, 1H), 3.21 (ddd, CHAN, J 12.8, 10.7, 3.6 Hz, 1H), 0.15 (s, CH3,
9H). 13C NMR: δ 150.3 (Ci), 145.9 (Cp), 128.3 (Co), 124.6 (Cm), 46.6 (CH2N), 42.5 (CHBr), -2.9
29
(CH3); Si NMR: δ 4.86. Anal. calcd for C11H17BrN2O4SSi: C C, 34.65; H, 4.49; N, 7.35; Br,
20.95; S, 8.41; Si, 7.37. Found: C, 34.64; H, 4.43; N, 7.30; Br, 20.78; S, 8.39; Si, 7.27.
1
2-Iodo-2-(trimethylsilyl)ethyl acetate, 4. Yellow oil. Yield 63%. H NMR: δ 4.38-4.26
(m, CH2OAc, 2H,), 3.29 (dd, СHI, J 8.9, 5.1 Hz, 1Н), 2.09 (s, СН3, 3Н), 0.19 (s, 3СН3, 9Н). 13C
29
NMR: δ 170.9 (С=О), 67.1 (СH2OAc), 21.0 (CH3C(O)), 15.2 (CHI), -1.9 (CH3). Si NMR: δ
5.89. Anal. calcd for C7H15IO2Si: C, 29.38; H, 5.28; I, 44.34; Si, 9.81. Found: C, C, 29.30; H,
5.15; I, 43.98; Si, 9.66.
1
N-[2-Iodo-2-(trimethylsilyl)ethyl]triflamide, 5. Yellow oil. Yield 20%. H NMR: δ 5.82
(t, NH, J 4.2 Hz, 1H), 3.65 (ddd, CHBN, J 14.6, 6.9, 3.3 Hz, 1H), 3.45 (ddd, CHAN, J 14.6, 11.1,
4.2 Hz, 1H), 3.21 (dd, CHI, J 11.1, 3.3 Hz, 1H), 0.20 c (s, 3CH3, 9H). 13C NMR: δ 119.6 (q, CF3,
J 321.1 Hz), 48.1 (CH2NH), 19.7 (CHI), -2.3 (CH3). 19F NMR: δ –77.2. 29Si NMR: δ 6.47. Anal.
calcd for C6H13F3INO2SSi: C, 19.21; H, 3.49; N, 3.73; F, 15.19; I, 33.82; S, 8.55; Si, 7.49.
Found: C, 19.14; H, 3.33; N, 3.70; F, 15.03; I, 33.25; S, 8.45; Si, 7.39.
N-(2-Bromo-2-(trimethylsilyl)ethyl)-N'-(triflyl)acetimidamide, 7. White solid. Mp 73
°C. Yield 81%. IR: 3333, 2958, 1583, 1556, 1427, 1354, 1323, 1255, 1210, 1137, 1053, 917,
846, 776, 742, 657, 594, 473 cm–1. 1H NMR: δ 6.47 (br. s, CHNH, 1H), 4.15 (dd, CHBr, J 13.4,
6.8 Hz), 3.39 (m, CH2, 2H), 2.53 (s, CH3C=N, 3H), 0.19 (s, CH3, 9H). 13C NMR: δ 168.6 (C=N),
119.3 (q, CF3, J 319.5 Hz), 45.8 (CH2N), 40.1 (CHBr), 21.9 (CH3-C=N), -3.38 (CH3). 19F NMR:
29
δ –79.2. Si NMR: δ 5.34. Anal. calcd for C8H16BrF3N2O2SSi: C, 26.02; H, 4.37; N, 7.59; F,
15.43; Br, 21.64; S, 8.68; Si, 7.61. Found: C, 25.99; H, 4.32; N, 7.55; F, 15.29; Br, 21.44; S,
8.59; Si, 7.49.
N-(4-(2-Bromo-2-(trimethylsilyl)ethoxy)butyl)triflamide, 8a. White solid. Mp 99 °C.
Yield 56%. IR: 3312, 2954, 2872, 2796, 1551, 1435, 1373, 1230, 1193, 1148, 1102, 989, 938,
848, 754, 699, 610, 499 cm–1. 1H NMR: δ 5.44 (t, NH, J 6.08 Hz, 1H), 3.82 (dd, J 11.2, 3.4 Hz,
1H), 3.68 (dd, J 11.2, 9.3 Hz, 1H), 3.55 (dt, J 9.7, 5.0 1H), 3.48 (dt, J 9.7, 4.5 Hz, 1H), 3.35 (m,
13
3H), 3.35 (m, 3H), 1.72 (m, 4H), 0.14 (s, CH3, 9H). C NMR: δ 119.7 (q, CF3, J 321.4 Hz),

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Organic & Biomolecular Chemistry
72.9, 70.3, 44.0, 40.8, 27.7, 26.5, -2.79 (CH3). 19F NMR: δ –77.3. 29Si NMR: δ 4.14. Anal. calcd
View Article Online
DOI: 10.1039/C9OB01689A
C10H21BrF3NO2SSi: %: C, 31.25; H, 5.51; N, 3.64; F, 14.83; Br, 20.79; S, 8.34; Si, 7.31. Found:
C, 31.22; H, 5.49; N, 3.60; F, 14.63; Br, 20.58; S, 8.27; Si, 7.24.
N-(4-(2-Bromo-2-(trimethylsilyl)ethoxy)butyl)-4-methylbenzenesulfonamide, 8d. Oil.
Yield 55%. IR: 3283, 2951, 2866, 1599, 1449, 1425, 1327, 1250, 1159, 1099, 847, 753, 697,
666, 552 cm–1. 1H NMR: δ 7.75 (d, o-CH, J 8.2 Hz, 2H), 7.29 (d, m-CH, J 8.2 Hz, 2H), 4.90 (br.
t, NH, J 5.8 Hz, 1H), 3.76 (dd, J 10.9, 3.8 Hz, 1H), 3.65 (dd, J 10.9, 8.8 Hz, 1H), 3.37 (m, 3H),
2.97 (m, 2H), 2.42 (s, CH3, 3H), 1.58 (m, 4H), 0.14 (s, CH3, 9H). 13C NMR: δ 143.1 (Cp), 137.0
29
(Ci), 129.6 (Cm), 127.0 (Co), 72.8, 70.2, 42.9, 41.0, 26.7, 26.6, 21.5, -2.6 (CH3). Si NMR: δ
3.86. Anal. calcd C16H28BrNO2SSi: %: C, 47.28; H, 6.94; N, 3.45; Br, 19.66; S, 7.89; Si, 6.91.
Found: C, 47.25; H, 6.90; N, 3.42; Br, 19.59; S, 7.77; Si, 6.86.
N-(4-(2-Bromo-2-(trimethylsilyl)ethoxy)butyl)-4-nitrobenzenesulfonamide, 8h. Oil.
Yield 77%. IR: 3293, 3106, 2951, 2866, 1606, 1531, 1473, 1421, 1348, 1313, 1251, 1164, 1100,
850, 740, 689, 614, 559 cm–1. 1H NMR: δ 8.34 (d, m-CH, J 8.8 Hz, 2H), 8.06 (d, o-CH, J 8.8 Hz,
2H), 5.45 (br. t, NH, J 5.8 Hz, 1H), 3.77 (dd, J 11.1, 3.5 Hz, 1H), 3.65 (dd, J 11.1, 9.8 Hz, 1H),
3.46 (m, 1H), 3.40 (m, 1H), 3.36 (m, 1H), 3.06 (m, 2H), 2.42 (s, CH3, 3H), 1.62 (m, 4H), 0.13 (s,
CH3, 9H). 13C NMR: δ 149.9 (Ci), 146.2 (Cp), 128.2 (Co), 124.2 (Cm), 72.8, 70.2, 43.0, 41.3,
29
27.0, 26.6, -2.7 (CH3). Si NMR: δ 4.08. Anal. calcd C15H25BrN2O4SSi: C, 41.19; H, 5.76; N,
6.40; Br, 18.27; S, 7.33; Si, 6.42. Found: C, 41.15; H, 5.74; N, 6.37; Br, 18.15; S, 7.30; Si, 6.40.
(1-Bromo-2-(4-bromobutoxy)ethyl)trimethylsilane, 9. Colorless liquid. Yields see in
Table 4. IR: 2951, 2862, 2790, 1469, 1445, 1359, 1251, 1112, 1051, 940, 847, 755, 699, 639,
1
560 cm–1. H NMR: δ 3.80 (dd, CHBO, J 10.9, 4.1 Hz), 3.72 (dd, CHAO, J 10.9, 7.9 Hz, 1H),
3.48 (m, CH2CH2, 4H), 3.37 (dd, CHBr, J 7.9, 4.1 Hz, 1H), 1.98 (m, CH2Br, 2H), 1.75 (m,
13
29
CH2O, 2H), 0.15 (s, CH3, 9H). C NMR: δ 73.1, 69.9, 41.0, 33.8, 29.7, 28.3, -2.4 (CH3). Si
NMR: δ 4.24. Anal. calcd C9H20Br2Si: %: C, 34.19; H, 6.38; Br, 50.55; Si, 8.88. Found: C,
34.15; H, 6.31; Br, 50.08; Si, 8.77.
1-(Methylsulfonyl)-2-(trimethylsilyl)aziridine, 10b. Light-yellow oil. IR: 3019, 2957,
2903, 1732, 1579, 1413, 1318, 1252, 1209, 1152, 1076, 955, 909, 848, 815, 784, 701, 648, 518
1
cm–1; H NMR: δ 3.02 (s, CH3, 3H), 2.59 (d, CHHN, J 8.5 Hz, 1H), 2.07 (d, CHHN, J 5.9 Hz,
1H), 1.93 (dd, CHN, J 8.5, 5.9 Hz, 1H), 0.09 (s, CH3, 9H). 13C NMR: δ 39.3 (CH3), 30.0
(CH2N), 29.4 (CHN), -3.5 (CH3). 29Si NMR: δ 1.77. Anal. calcd. for C6H15NO2SSi: C, 37.27; H,
7.82; N, 7.24; S, 16.58; Si, 14.53. Found: C, 37.22; H, 7.76; N, 7.18; S, 16.48; Si, 14.50.
1-(Phenylsulfonyl)-2-(trimethylsilyl)aziridine, 10c. Light-yellow oil. IR: 2957, 1448,
1321, 1252, 1207, 1162, 1091, 954, 904, 846, 738, 690, 662, 595, 542 cm–1; 1H NMR: δ 7.92 (d,
o-CH, J 7.8 Hz, 2H), 7.62 (t, p-CH, J 7.8 Hz, 1H), 7.52 (t, m-CH, J 7.8 Hz, 2H), 2.69 (d, CHHN,

Organic & Biomolecular Chemistry
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J 8.7 Hz, 1H), 2.07 (d, CHHN, J 5.8 Hz, 2H), 1.91 (dd, CHN, J 8.7, 5.8 Hz, 2H), -0.12 (s, CH3,
View Article Online
13
DOI: 10.1039/C9OB01689A
9H). C NMR: δ 138.0 (Ci), 133.3 (Cp), 128.8 (Co), 127.9 (Cm), 30.3 (CH2N), 30.0 (CHN), -3.9
(CH3). 29Si NMR: δ 1.44. Anal. calcd. for C11H17NO2SSi: C, 51.73; H, 6.71; N, 5.48; S, 12.55;
Si, 11.00; found: C, 51.70; H, 6.56; N, 5.45; S, 12.49; Si, 10.94.
1-Tosyl-2-(trimethylsilyl)aziridine, 10d. Light-yellow oil. IR: 2958, 2900, 1921, 1598,
1494, 1451, 1408, 1323, 1299, 1253, 1208, 1158, 1094, 954, 905, 847, 815, 758, 700, 656, 557,
1
494 cm–1; H NMR: δ 7.78 (d, o-CH, J 8.2 Hz, 2H), 7.29 (d, m-CH, J 8.2 Hz, 2H), 2.63 (d,
CHHN, J 8.7 Hz, 1H), 2.40 (s, CH3Ph, 3H), 2.03 (d, CHHN, J 5.8 Hz, 1H), 1.87 (dd, CHN, J
8.7, 5.8 Hz, 1H), -0.12 (s, CH3, 3H). 13C NMR: δ 144.0 (Cp), 134.7 (Ci), 129.2 (Cm), 127.7 (Co),
30.0 (CHN), 29.5 (CH2N), 21.2 (CH3Ph), -4.1 (CH3). 29Si NMR: δ 1.49. Anal. calcd. for
C12H19NO2SSi: C, 53.49; H, 7.11; N, 5.20; S, 11.90; Si, 10.42; found: C, 53.45; H, 7.08; N, 5.20;
S, 11.84; Si, 10.40.
1-((4-Methoxyphenyl)sulfonyl)-2-(trimethylsilyl)aziridine, 10e. Light-yellow oil. IR:
3074, 2957, 2903, 2844, 1907, 1730, 1594, 1498, 1461, 1414, 1322, 1259, 1207, 1155, 1097,
1
1025, 954, 905, 844, 812, 758, 699, 657, 566 cm–1; H NMR: δ 7.84 (d, o-CH, J 8.8 Hz, 2H),
6.98 (d, m-CH, J 8.8 Hz, 2H), 3.86 (s, CH3O, 3H), 2.63 (d, CHHN, J 8.5 Hz, 1H), 2.04 (d,
CHHN, J 5.9 Hz, 1H), 1.85 (dd, CHN, J 8.5, 5.9 Hz, 1H), -0.10 (s, CH3, 3H). 13C NMR: δ 163.6
(Cp), 130.3 (Co), 129.7 (Ci), 114.1 (Cm), 55.7 (MeO), 30.4 (CHN), 30.0 (CH2N), -3.7 (CH3). 29Si
NMR: δ 1.48. Anal. calcd. for C6H15NO2SSi: C, 50.49; H, 6.71; N, 4.91; S, 11.23; Si, 9.84;
Found: C, 50.50; H, 6.71; N, 4.90; O, 16.82; S, 11.23; Si, 9.84.
1-((4-Chlorophenyl)sulfonyl)-2-(trimethylsilyl)aziridine, 10f. Light-yellow oil. IR: 3092,
2958, 1582, 1475, 1396, 1327, 1253, 1208, 1163, 1091, 1014, 954, 905, 846, 761, 707, 673, 626,
544, 482 cm–1; 1H NMR: δ 7.85 (d, o-CH, J 8.4 Hz, 2H), 7.49 (d, m-CH, J 8.4 Hz, 2H), 2.66 (d,
CHHN, J 8.6 Hz, 1H), 2.07 (d, CHHN, J 5.8 Hz, 1H), 1.93 (dd, CHN, J 8.6, 5.8 Hz, 1H), -0.10
(s, CH3, 9H); 13C NMR: δ 139.7 (Cp), 136.6 (Ci), 129.4 (Co), 129.1 (Cm), 30.5 (CH2N), 30.2
29
(CHN), -3.9 (CH3), Si NMR: δ 1.71. Anal. calcd. for C11H16ClNO2SSi: C, 45.58; H, 5.56; N,
4.83; S, 11.06; Si, 9.69; Cl, 12.23; found: C, 45.37; H, 5.41; N, 4.46; S, 11.03; Si, 9.57; Cl,
12.19.
1-((4-Bromophenyl)sulfonyl)-2-(trimethylsilyl)aziridine, 10g. Light-yellow oil, IR:
3090, 2957, 2900, 1647, 1574, 1468, 1390, 1327, 1252, 1208, 1162, 1091, 1070, 1010, 954, 905,
846, 755, 704, 668, 616, 586, 543, 416 cm–1. 1H NMR: δ 7.81 (d, o-CH, J 8.5 Hz, 2H), 7.69 (d,
m-CH, J 8.5 Hz, 2H), 2.69 (d, CHHN, J 8.4 Hz, 1H), 2.09 (d, CHHN, J 5.9 Hz, 1H), 1.97 (dd,
13
CHN, J 8.4, 5.9 Hz, 1H), -0.06 (s, CH3, 9H). C NMR: δ 137.5 (Ci), 132.3 (Cm), 129.7 (Co),
128.6 (Cp), 30.8 (CH2N), 30.6 (CHN), -3.7 (CH3). 29Si NMR: δ 1.71. Anal. calcd. for

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Organic & Biomolecular Chemistry
C11H16BrNO2SSi: C, 39.52; H, 4.82; N, 4.19; Br, 23.90; S, 9.59; Si, 8.40; found: C, 39.51; H,
View Article Online
DOI: 10.1039/C9OB01689A
4.80; N, 4.17; Br, 23.76; S, 9.55; Si, 8.38.
1-((4-Nitrophenyl)sulfonyl)-2-(trimethylsilyl)aziridine, 10h. White solid, Mp 128 °C.
IR: 3102, 2957, 1606, 1527, 1404, 1305, 1249, 1210, 1170, 1090, 955, 896, 845, 752, 687, 613,
539, 459 cm–1; 1H NMR: δ 8.40 (d, m-CH, J 8.7 Hz, 2H), 8.16 (d, o-CH, J 8.7 Hz, 2H), 2.77 (d,
CHHN, J 8.5 Hz, 1H), 2.15 (d, CHHN, J 6.0 Hz, 1H), 2.09 (dd, CHN, J 8.5, 6.0 Hz, 1H), -0.04
(s, CH3, 3H). 13C NMR: δ 150.6 (Ci), 144.2 (Cp), 129.4 (Co), 124.2 (Cm), 31.3 (CH2N), 31.1
(CHN), -3.7 (CH3). 29Si NMR: δ 1.90. Anal. calcd. for C11H16N2O4SSi: C, 43.98; H, 5.37; N,
9.33; S, 10.67; Si, 9.35; found: C, 43.95; H, 5.30; N, 9.31; S, 10.60; Si, 9.29.
1
N-(2-Bromoethyl)benzenesulfonamide, 11c. White solid. H NMR: δ 7.90 (d, m-CH, J
8.0 Hz, 2H), 7.60-7.64 (m, p-CH, 1H), 7.54-7.58 (m, o-CH, 2H), 5.11 (bs, NH, 1H), 3.39-3.43
(m, 2CH2, 4H). 13C NMR: δ 139.8 (Ci), 132.9 (Cp), 129.3 (Co), 126.9 (Cm), 44.5 (CH2NH), 31.4
(CH2Br). Anal. calcd. for C8H10BrNO2S: C, 36.38; H, 3.82; N, 5.30; S, 12.14; Br, 30.25; found:
C, 36.33; H, 3.78; N, 5.26; S, 12.02; Br, 30.01.
1
N-(2-Bromoethyl)-4-methylbenzenesulfonamide, 11d. White solid. H NMR: δ 7.78 (d,
m-CH, J 8.2 Hz, 2H), 7.34 (d, o-CH, J 8.2 Hz, 2H), 4.96 (bs, NH, 1H), 3.40 - 3.35 (m, 2CH2,
4H), 2.46 (s, CH3, 3H). 13C NMR: δ 143.8 (Ci), 136.9 (Cp), 129.9 (Co), 127.0 (Cm), 44.5
(CH2NH), 31.7 (CH2Br). 21.5 (CH3). Anal. calcd. for C9H12BrNO2S: C, 38.86; H, 4.35; N, 5.04;
S, 11.53; Br, 28.73; found: C, 38.80; H, 4.33; N, 4.99; S, 11.42; Br, 28.20.
2-Methyl-1-(triflyl)-5-(trimethylsilyl)-4,5-dihydro-1H-imidazole, 13. Oil. IR: 2959,
2879, 1673, 1400, 1233, 1201, 1154, 1089, 1053, 988, 961, 917, 849, 758, 668, 615, 581, 536
1
cm–1. H NMR: δ 4.05 (m, CH, 1H), 3.82 (m, CH2, 2H), 2.25 (s, CH3C=N, 3H), 0.12 (s, CH3,
9H). 13C NMR: δ 154.9 (C=N), 120.4 (q, CF3, J 325.9 Hz), 56.2 (CH2N), 53.9 (CHN), 16.7
(CH3-C=N), -3.8 (CH3). 19F NMR: δ –73.8. 29Si NMR: δ 4.63. Anal. calcd for C8H15F3N2O2SSi:
C, 33.32; H, 5.24; N, 9.71; S, 11.12; Si, 9.74; F, 19.77. Found: C, 33.28; H, 5.23; N, 9.70; S,
11.06; Si, 9.68; F, 19.65.
4-((Trifluoromethyl)sulfonyl)-3-(trimethylsilyl)-1,4-oxazocane, 14. Oil. IR: 2948, 2864,
1640, 1455, 1366, 1248, 1199, 1154, 1087, 988, 910, 845, 745, 699, 614, 503 cm–1. 1H NMR: δ
4.01 (br. s, NH, 1H), 3.79 (dd, J 11.2, 3.3 Hz, 1H), 3.69 (dd, J 11.3, 9.6 Hz, 1H), 3.46 (m, 3H),
3.03 (t, J 5.5 Hz, 2H), 1.56 (m, 4H), 0.16 (s, CH3, 9H). 13C NMR: δ 122.1 (q, CF3, J 321.4 Hz),
19
29
72.8, 70.8, 45.0, 41.5, 29.0, 27.1, -2.6 (CH3). F NMR: δ –76.7. Si NMR: δ 4.09. Anal. calcd
C10H20F3NO3SSi: %: C, 37.60; H, 6.31; N, 4.39; S, 10.04; Si, 8.79; F, 17.84. Found: C, 37.57; H,
6.26; N, 4.35; S, 10.00; Si, 8.71; F, 17.78.

Organic & Biomolecular Chemistry
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Conflicts of interest
View Article Online
DOI: 10.1039/C9OB01689A
There are no conflicts of interests to declare.
Acknowledgments
This work was performed using the equipment of the Baikal Analytical Center for Collective
Use of SB RAS and was partly supported by RFBR Grants 17-03-00213 and 18-33-20131.
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