Synthesis of 2-imino-1,3-dithiolanes containing trimethylsilylethynylthiolato groups

Article abstract of DOI:10.1080/17415993.2016.1146721

An efficient, eco-friendly, and simple one-pot approach for the synthesis of 2-imino-1,3-dithiolanes via reaction of allyl chloride, primary amines, carbon disulfide, and I₂ under solvent-free conditions is presented. The obtained 5-iodomethyl-2-imino-1,3-dithiolanes were converted into silyl-protected terminal alkynyl sulfides substituted 2-imino-1,3-dithiolanes by treatment with lithium 2,2,2-tris(trimethylsilyl)ethanedithioate, produced by the reaction of tris(trimethylsilyl)methyllithium (TsiLi) with CS₂.

Full text of DOI:10.1080/17415993.2016.1146721

Journal of Sulfur Chemistry
ISSN: 1741-5993 (Print) 1741-6000 (Online) Journal homepage: http://www.tandfonline.com/loi/gsrp20
Synthesis of 2-imino-1,3-dithiolanes containing
trimethylsilylethynylthiolato groups
Kazem D. Safa & Maryam Alyari
To cite this article: Kazem D. Safa & Maryam Alyari (2016): Synthesis of 2-imino-1,3-
dithiolanes containing trimethylsilylethynylthiolato groups, Journal of Sulfur Chemistry, DOI:
10.1080/17415993.2016.1146721
To link to this article: http://dx.doi.org/10.1080/17415993.2016.1146721
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Date: 02 March 2016, At: 00:19

JOURNAL OF SULFUR CHEMISTRY, 2016
http://dx.doi.org/10.1080/17415993.2016.1146721
Synthesis of 2-imino-1,3-dithiolanes containing
trimethylsilylethynylthiolato groups
Kazem D. Safa and Maryam Alyari
Organosilicon Research Laboratory, Chemistry Department, University of Tabriz, Tabriz, Iran
ABSTRACT
ARTICLE HISTORY
Received 5 November 2015
Accepted 22 January 2016
An efficient, eco-friendly, and simple one-pot approach for the
synthesis of 2-imino-1,3-dithiolanes via reaction of allyl chlo-
ride, primary amines, carbon disulfide, and I2 under solvent-free
conditions is presented. The obtained 5-iodomethyl-2-imino-1,3-
dithiolanes were converted into silyl-protected terminal alkynyl sul-
fides substituted 2-imino-1,3-dithiolanes by treatment with lithium
2,2,2-tris(trimethylsilyl)ethanedithioate, produced by the reaction of
tris(trimethylsilyl)methyllithium (TsiLi) with CS2.
KEYWORDS
Allyl chloride; carbon
disulfide; tris(trimethylsilyl)
methyllithium; 2-imino-1;
3-dithiolane; alkynyl sulfide
1. Introduction
Sulfur-containing compounds exist widely in nature and are extensively used in synthetic
sequences. Hence, the selective formation of C–S bonds has received considerable
attention.[1–9] Alkynyl thiolates are essential building blocks in organic synthesis as
they combine the enhanced reactivity of the triple bond with a sulfur atom, frequently
encountered in bioactive compounds and materials.[10–13] Currently, the most common
techniques require elimination processes or functionalization of the thiol by the formation
of a bond between sulfur and sp-hybridized carbon.[14,15] We focus on compounds of
biological importance that contain trimethylsilylethynyl groups.
Derivatives of 2-imino-1,3dithiolane, a five-membered heterocyclic compound con-
=
taining two S atoms attached to the carbon of the C N bond, have received consid-
erable attention because of their wide range of applications and their diverse biological
activities.[16]
CONTACT Kazem D. Safa
dsafa@tabrizu.ac.ir
Organosilicon Research Laboratory, Chemistry Department,
University of Tabriz, 5166616471, Tabriz, Iran
This article makes reference to supplementary material available on the publisher’s website at http://dx.doi.org/
10.1080/17415993.2016.1146721
© 2016 Taylor & Francis

2
K. D. SAFA AND M. ALYARI
Herein, we report our investigation regarding iodocyclization of S-allyl dithiocarba-
mates using I2 as the electrophile to give corresponding 2-imino-1,3-dithiolanes. Then
we describe a novel and efficient preparation of silyl-protected terminal alkynyl sulfides on
these biologically active compounds.
2. Results and discussion
Recently, Saidi et al. [16] described a new and efficient method for the synthesis of
2-imino-1,3-dithiolane involving the reaction of allyl chloride, primary amines, and car-
bon disulfide in H2O to afford S-allyl dithiocarbamates, then iodocyclization of these
compounds in CH2Cl2 produced 4-(iodomethyl)-2-imino-1,3-dithiolane. This method
suffers from several disadvantages such as the use of harmful organic solvent and pro-
longed reaction time. Therefore, searching for more facile and practical synthetic routes
to 2-imino-1,3-dithiolane is still desirable work. To improve the synthesis of 2-imino-
1,3-dithiolane, herein we report a novel, efficient, and eco-friendly synthesis of these
compounds under solvent-free conditions by the reaction of allyl chloride, primary amines,
carbon disulfide, and I2.
We began by examining the reaction of allyl chloride, propylamine and one equivalent of
CS2 in CH2Cl2 at 0°C without any catalyst. After 5 min, 1 equivalent of I2 was added to the
mixture at room temperature. This reaction afforded the desired 2-imino-1,3-dithiolane
2b in 65% yield. In order to improve the reaction efficiency, we varied the molar ratios of
the reactions. Furthermore, we found out that the reaction could occur more efficiently
in the presence of K2CO3 as the catalyst. Potassium dithiocarbamates are obtained by the
reaction of allyl chloride, propyl amine, and carbon disulfide in the presence of K2CO3.
This method has the advantages that only one equivalent of amine is required. We further
investigated this reaction by changing the number of equivalents of I2 and the solvent. The
results are summarized in Table 1.
Encouraged by these results, the synthesis of 2-imino-1,3-dithiolane 2a–2f has been
carried out using 3 equivalent of I2 under solvent-free conditions (Table 2). It should be
Table 1. Screening of reaction conditions for synthesis of 2-imino-1,3-dithiolane (2b).
Entry
Catalyst (equiv.)
Molar ratio CS2/I2
Solvent
Time/min
Yield (%)a
1
2
3
4
5
6
9
13
14
15
None
None
K2CO3 (1)
None
K2CO3 (1)
None
K2CO3 (1)
None
None
1:1
1:1
CH2Cl2
THF
THF
CH2Cl2
CH2Cl2
H2O
H2O
Solvent-free
Solvent-free
Solvent-free
40
45
20
35
20
15
10
20
10
5
65
60
85
80
90
86
92
70
91
94
1.5:3
1.5:3
1.5:3
1.5:3
1.5:3
1:1
1.5:3
1.5:3
K2CO3 (1)
aIsolated yield based on 2b.

JOURNAL OF SULFUR CHEMISTRY
3
Table 2. Synthesis of 2-imino-1,3-dithiolanes.
Entry
1
Product
Time/min
Yield (%)a
1
2
3
4
5
6
PhCH2NH2
n-PrNH2
iso-PrNH2
c-C6H11NH2
N-morpholinoNH2
sec-BuNH2
2a
2b
2c
2d
2e
2f
20
22
25
21
18
20
96
94
95
100
98
95
aIsolated yield.
Table 3. The results of the preparation of N-substituted-5-trimethylsilylethenylthiomethyl-
2-imino-1,3-dithiolanes.
Entry
R1
CH2Ph
n-Pr
iso-Pr
c-C6H11
N-morpholino
sec-Bu
Product
Time/min
Yield (%)a
1
2
3
4
5
6
3a
3b
3c
3d
3e
3f
10
20
20
15
10
20
87
85
86
89
88
85
aIsolated yield.
noted that, in all aforementioned experiments, the alternative 6-endo-trig cyclization was
never detected.[16]
Recently, we have embarked on a program directed towards the use of tris(trimethylsilyl)
methane, (Me3Si)3CH, for the generation of synthetically useful organosilicon compounds.
[17,18] In addition, we have investigated the behavior of tris(trimethylsilyl)methyllithium
(TsiLi) with carbon disulfide at low temperature.[19,20] In the previous publications
we reported the new type of chemistry of carbon disulfide proceeding via nucleophilic
attack of TsiLi at carbon of carbon disulfide in the presence of various 5-iodomethyl
thiazolidine-2-thiones at temperature ranging from 0°C to 25°C.[21] The reactions of the
newly synthesized 2-imino-1,3-dithiolanes with TsiLi in the presence of carbon disulfide
are summarized in Table 3.
The precursor (Me3Si)3CH was prepared by the reaction of chloroform, Li,
and trimethylsilyl chloride in tetrahydrofuran (THF). The organolithium reagent,
(Me3Si)3CLi, was obtained by the treatment of (Me3Si)3CH with methyllithium under
reflux conditions in THF (Scheme 1).[22]

4
K. D. SAFA AND M. ALYARI
Scheme 1. The reaction of TsiLi, CS2, and 4-(iodomethyl)-2-imino-1,3-dithiolane.
The 1H and 13C nuclear magnetic resonance (NMR) spectra show 1:1 mixtures of E/Z
stereoisomers of 4-trimethylsilylethynylthiomethyl-2-imino-1,3-dithiolanes 3. See supple-
mental data, http://dx.doi.org/10.1080/17415993.2016.1146721. The NMR spectra show
the presence of an E/Z (1:1) mixture of compound 3 due to the imine and triple bonds
(Figure 1).
To highlight the utility of alkynyl sulfides, the product 3b was desilylated using a base
such as K2CO3, KOH, or NaN3 in methanol, furnishing the corresponding terminal alkyne.
Furthermore, the cycloaddition reaction of 3b with benzyl azide, formed in situ from
benzyl bromide and sodium azide, gave the compound 4 in 93% yield (Scheme 2).
Figure 1. (a) 1H NMR and (b) 13C NMR spectra of 3b in CDCl3.
Scheme 2. The 1,3-dipolar cycloaddition between azide and 3b.

JOURNAL OF SULFUR CHEMISTRY
5
3. Conclusion
We have reported a eco-friendly and efficient protocol for synthesis of 2-imino-1,3-
dithiolane derivatives starting from allyl chloride, primary amines, carbon disulfide, andI2.
Then, we have described an efficient preparation of silyl-protected alkynylthiolato deriva-
tives of 2-amino-1,3-dithiolanes.The potential synthetic utility of the resulting alkynylthi-
olates was demonstrated through a copper-catalysed azide–alkyne cycloaddition reaction
(CuAAC).
4. Experimental
4.1. Solvents and reagents
Reactions involving organolithium reagents were carried out under dry argon. Sol-
vents and CS2 were dried by standard methods. Substrates for the preparation of
tris(trimethylsilyl)methyllithium, namely, Me3SiCl, Li, CHCl3, and substrates for the
preparation of 2-imino-1,3-dithiolane, namely, allyl chloride, primary amines, iodine, and
K2CO3, were purchased from Merck and Fluka.
4.2. Instrumentation
The 1H NMR and 13C NMR were recorded with a Bruker FT-400 MHz spectrometer at
room temperature and CDCl3 as a solvent. The Fourier transform infrared (FTIR) spectra
were recorded on a Bruker-Tensor 270 spectrometer. Elemental analyses were carried out
with a Heareus CHN-ORAPID instrument.
4.3. General procedure for the preparation of 4-(iodomethyl)-2-imino-1,3-
dithiolane
To a well-stirred mixture of allyl chloride (1 mmol), K2CO3 (1 mmol), and CS2 (1.5 mmol)
primary amine (1 mmol) was added drop-wise over 2 min at 0°C, and the stirring was
continued for 3 min at 0°C. The mixture was allowed to warm to room temperature,
then stirred for 5 min. I2 (3 mmol) was added and stirring was maintained until the end
of the reaction (as shown by thin-layer chromatography (TLC)). Then the mixture was
treated with 2 M aq NaHSO3 solution (5 mL) and extracted with CH2Cl2 (2 × 10 mL). The
organic layer was dried (Na2SO4), filtered and the solvent was evaporated from the fil-
trate under reduced pressure. In most cases, the pure products were obtained. If needed,
further purification was carried out by column chromatography on silica gel, using n-
hexane and ethyl acetate (5:1) as eluent. Compounds 2a, 2d, and 2f have been described
previously.[16]
4.3.1. N-propyl-4-(iodomethyl)-2-imino-1,3-dithiolane (2b)
Yellow sticky solid, 94% (Rf = 0.41). FTIR (KBr, cm−1): 1610 (C N), 2874, 2930, 2962;
=
1H NMR (400 MHz, CDCl3): δ 0.93–0.96 (m, 6H), 1.60–1.69 (m, 4H), 3.08–3.15 (m,
4H), 3.40–3.47 (m, 4H), 3.49–3.53 (dd, J = 4.2, 12.1 Hz, 1H), 3.58–3.62 (dd, J = 4.8,
12.1 Hz, 1H), 3.70–3.74 (dd, J = 4.8, 12.1 Hz, 1H), 3.79–3.83 (dd, J = 3.3, 12.1 Hz,
1H), 4.15–4.18 (m, 1H), 4.26–4.28 (m, 1H); 13C NMR (100 MHz, CDCl3): δ 6.22,

6
K. D. SAFA AND M. ALYARI
=
6.51, 11.09, 11.13, 24.83, 39.62, 42.29, 47.28, 50.86, 54. 03, 164.13 and 164.32 (C N);
Anal. Calcd for C7H12INS2: C, 27.91; H, 4.02; N, 4.65. Found: C, 28.02; H, 4.13;
N, 4.58.
4.3.2. N-isopropyl-4-(iodomethyl)-2-imino-1,3-dithiolane (2c)
Yellow sticky solid, 95% (Rf = 0.41). FTIR (KBr, cm−1): 1608 (C N), 2872, 2929, 2961;
=
1H NMR (400 MHz, CDCl3): δ 1.18–1.21 (m, 12H), 3.03–3.15 (m, 4H), 3.38–3.45 (m, 4H),
3.43–3.47 (dd, J = 4.1, 12.1 Hz, 1H), 3.50–3.54 (dd, J = 4.8, 12.1 Hz, 1H), 3.72–4.76 (dd,
J = 4.8, 12.1 Hz, 1H), 3.81–3.85 (dd, J = 3.3, 12.1 Hz, 1H), 4.12–4.15 (m, 1H), 4.20–4.24
(m, 1H); 13C NMR (100 MHz, CDCl3): δ 6.17, 6.48, 19.52, 19.56, 37.21, 38.95, 50.13, 52.74,
=
55.32, 163.44 and 163.82 (C N); Anal. Calcd for C7H12INS2: C, 27.91; H, 4.02; N, 4.65.
Found: C, 28.08; H, 4.19; N, 4.52.
4.3.3. N-morpholino-4-(iodomethyl)-2-imino-1,3-dithiolane (2e)
Yellow sticky solid, 98% (Rf = 0.32). FTIR (KBr, cm−1): 1662 (C N), 2868, 2919, 2960;
=
1H NMR (400 MHz, CDCl3): δ 2.68–2.80 (m, 8H), 3.02–3.15 (m, 4H), 3.42–3.54 (m, 4H),
3.49–3.58 (m, 2H), 3.74–3.90 (m, 6H), 4.08–4.12 (m, 1H), 4.18–4.22 (m, 1H); 13C NMR
(100 MHz, CDCl3): δ 6.18, 6.53, 38.24, 40.06, 49.28, 50.61, 53.81, 53.83, 65.30, 65.31, 164.64
=
and 164.75 (C N); Anal. Calcd for C8H13IN2OS2: C, 27.91; H, 3.81; N, 8.14. Found: C,
28.02; H, 3.98; N, 8.09.
4.4. General procedure for the preparation of 4-trimethylsilylethynylthiomethyl-
2-imino-1,3-dithiolanes
To a stirred solution of tris(trimethylsilyl)methyllithium (1 mmol) in THF, 2-imino-1,3-
dithiolane (1 mmol) in 2 mL THF was added at room temperature under argon atmo-
sphere. The progress of the reaction was followed by TLC. After completion of the reaction,
the mixture is poured into water and extracted with CH2Cl2. The organic layer was washed
with water, dried over Na2SO4, and filtered. The solvent was evaporated and the residue
was purified by preparative TLC on silica gel using n-hexane/ethyl acetate (5:1) as eluent
to give the product.
4.4.1. E/Z (1:1) mixture of N-benzyl-4-trimethylsilylethynylthiomethyl-2-imino-
1,3-dithiolane (3a)
Brown oil, 87% (Rf = 0.37). FTIR (KBr, cm−1): 842, 878 and 1282 (–SiMe3), 1602 (C N),
=
1
2092 (C≡C), 2874, 2959, 3029; H NMR (400 MHz, CDCl3): δ 0.19 (s, 18H, –SiMe3),
3.04–3.18 (m, 4H, –CH2Ph), 3.59–3.63 (dd, J = 4.1, 12.1 Hz, 1H), 3.65–3.69 (dd, J = 4.8,
12.1 Hz, 1H), 3.78–3.82 (dd, J = 4.8, 12.1 Hz, 1H), 3.88–3.92 (dd, J = 3.3, 12.1 Hz, 1H),
4.08–4.13 (m, 1H), 4.31–4.37 (m, 1H), 4.45–4.54 (m, 4H), 7.26–7.28 (m, 2H, Ar), 7.34 (m,
8H, Ar); 13C NMR (100 MHz, CDCl3): δ −1.14 (–SiMe3), 36.24, 37.04, 37.20, 39.11, 47.56,
51.42, 61.70, 61.75, 91.09 and 91.18 (C≡C), 101.66 and 101.81 (C≡C), 126.04, 126.80,
=
127.44, 129.85, 164.01 and 164.56 (C N); MS (EI, 70 eV): m/z (%) = 73 (87), 91 (100),
187 (67), 351 (7) [M]+.

JOURNAL OF SULFUR CHEMISTRY
7
4.4.2. E/Z (1:1) mixture of N-propyl-4-trimethylsilylethynylthiomethyl-2-imino-
1,3-dithiolane (3b)
Red oil, 85% (Rf = 0.40). FTIR (KBr, cm−1): 843, 879 and 1250 (–SiMe3), 1606 (C N),
=
1
2092 (C≡C), 2872, 2928, 2960; H NMR (400 MHz, CDCl3): δ 0.17 (s, 18H, –SiMe3),
0.91–0.95 (m, 6H, –CH3), 1.63–1.73 (m, 4H), 3.03–3.11 (m, 4H), 3.19–3.24 (m, 4H),
3.53–3.57 (dd, J = 4.1, 12.1 Hz, 1H), 3.59–3.63 (dd, J = 4.8, 12.1 Hz, 1H), 3.71–3.75 (dd,
J = 4.9, 12.1 Hz, 1H), 3.82–3.86 (dd, J = 3.3, 12.1 Hz, 1H), 4.02–4.06 (m, 1H), 4.26–4.29
(m, 1H); 13C NMR (100 MHz, CDCl3): δ −1.17 (–SiMe3), 10.92, 10.93, 22.66, 35.93, 37.03,
37.24, 38.78, 47.15, 50.98, 60.24, 60.28, 91.18 and 91.24 (C≡C), 101.48 and 101.60 (C≡C),
=
163.44 and 164.13 (C N); MS (EI, 70 eV): m/z (%) = 73 (100), 91 (12), 97 (13), 187 (59),
303 (10) [M]+.
4.4.3. E/Z (1:1) mixture of N-isopropyl-4-trimethylsilylethynylthiomethyl-
2-imino-1,3-dithiolane (3c)
Red oil, 86% (Rf = 0.35). FTIR (KBr, cm−1): 842, 878 and 1250 (–SiMe3), 1600 (C N),
=
1
2093 (C≡C), 2866, 2927, 2962; H NMR (400 MHz, CDCl3): δ 0.18 (s, 18H, –SiMe3),
1.23–1.24 (m, 12H, –CH3), 3.00–3.15 (m, 4H), 3.40–3.41 (m, 2H), 3.57–3.64 (m, 2H),
3.75–3.79 (dd, J = 4.8, 12.1 Hz, 1H), 3.87–3.91 (dd, J = 3.3, 12.1 Hz, 1H), 4.09–4.10 (m,
1H), 4.31–4.33 (m, 1H); 13C NMR (100 MHz, CDCl3): δ −1.14 (–SiMe3), 21.67, 21.77,
36.86, 37.15, 38.91, 52.42, 59.59, 59.64, 90.96 and 91.05 (C≡C), 98.47 and 98.62 (C≡C),
=
163.40 and 164.09 (C N); MS (EI, 70 eV): m/z (%) = 73 (100), 91 (30), 97 (21), 187 (62),
303 (10) [M]+.
4.4.4. E/Z (1:1) mixture of N-cyclohexyl-4-trimethylsilylethynylthiomethyl-2-
imino-1,3- dithiolane (3d)
Red oil, 89% (Rf = 0.34). FTIR (KBr, cm−1): 842, 879 and 1249 (–SiMe3), 1595 (C N),
=
2091 (C≡C), 2852, 2927; 1H NMR (400 MHz, CDCl3): δ 0.18 (s, 18H, –SiMe3), 1.15–1.45
(m, 10H), 1.61–1.79 (m, 12H), 3.00–3.15 (m, 4H), 3.55–3.64 (m, 2H), 3.73–3.77 (dd,
J = 4.8, 12.1 Hz, 1H), 3.84–3.88 (dd, J = 3.2, 12.1 Hz, 1H), 4.04–4.12 (m, 1H), 4.27–4.33
(m, 1H); 13C NMR (100 MHz, CDCl3): δ −1.13 (–SiMe3), 7.60, 23.68, 24.43, 31.81, 36.95,
37.29, 38.76, 44.75, 51.90, 59.43, 59.49, 91.12 and 91.18 (C≡C), 101.54 and 101.68 (C≡C),
=
163.38 and 163.95 (C N); MS (EI, 70 eV): m/z (%) = 73 (100), 91 (43), 99 (87), 207 (32),
281 (29), 343 (12) [M]+.
4.4.5. E/Z (1:1) mixture of N-morpholino-4-trimethylsilylethynylthiomethyl-2-
imino-1,3-dithiolane (3e)
Brown oil, 88% (Rf = 0.31). FTIR (KBr, cm−1): 843, 878 and 1253 (–SiMe3), 1559 (C N),
=
1
2092 (C≡C), 2837, 2914, 2958; H NMR (400 MHz, CDCl3): δ 0.17 (s, 18H, –SiMe3),
2.80–2.93 (m, 8H), 2.98–3.11 (m, 4H), 3.54–3.68 (m, 4H), 3.77–3.80 (m, 8H), 4.05–4.15
(m, 2H); 13C NMR (100 MHz, CDCl3): δ −1.15 (–SiMe3), 36.42, 37.05, 37.18, 37.83, 48.03,
49.50, 53.81, 53.83, 65.30, 65.31, 91.12 and 91.25 (C≡C), 101.72 and 101.75 (C≡C),
=
171.19 and 171.35 (C N); MS (EI, 70 eV): m/z (%) = 73 (73), 91 (15), 97 (23), 207 (55),
346 (100) [M]+.

8
K. D. SAFA AND M. ALYARI
4.4.6. E/Z (1:1) mixture of N-(sec-butyl)-4-trimethylsilylethynylthiomethyl-2-
imino-1,3-dithiolane (3f)
Red oil, 85% (Rf = 0.45). FTIR (KBr, cm−1): 842, 878 and 1250 (–SiMe3), 1607 (C N),
=
1
2093 (C≡C), 2872, 2899, 2958; H NMR (400 MHz, CDCl3): δ 0.16 (s, 18H, –SiMe3),
0.93 (d, J = 6.6 Hz, 12H), 1.93–2.02 (m, 2H), 2.99–3.14 (m, 8H), 3.57–3.61 (dd, J = 4.2,
12.1 Hz, 1H), 3.62–3.66 (dd, J = 4.8, 12.2 Hz, 1H), 3.73–3.77 (dd, J = 4.9, 12.1 Hz, 1H),
3.84–3.88 (dd, J = 3.3, 12.1 Hz, 1H), 4.06–4.11 (m, 1H), 4.27–4.32 (m, 1H); 13C NMR
(100 MHz, CDCl3): δ −1.19 (–SiMe3), 19.55, 28.44, 28.61, 36.45, 36.91, 37.12, 38.85, 47.80,
51.30, 65.77, 65.81, 91.01 and 91.14 (C≡C), 101.61 and 101.79 (C≡C), 168.82 and 169.26
=
(C N); MS (EI, 70 eV): m/z (%) = 73 (100), 91 (10), 97 (14), 187 (64), 202 (27), 317 (10)
[M]+.
4.5. Preparation of 4-(((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)thio)-N-propyl-2-
imino-1,3-dithiolane (4)
To a solution ofN-propyl-4-trimethylsilylethynylthiomethyl-2-imino-1,3-dithiolane (0.30 g,
1 mmol) in methanol (5 mL) sodium azide (0.16 g, 2.5 mmol), benzyl bromide (0.17 g,
1 mmol), and CuCl (0.99 g, 0.01 mmol) were added and the mixture was stirred for 12 h at
75°C. The reaction mixture was then concentrated in vacuum, and the residue was diluted
with ether, washed with water, brine and dried over MgSO4, filtered and concentrated
in vacuum. Purification by flash chromatography eluting with 1:1 n-hexane/ethyl acetate
yielded the title compound. Pale yellow solid, 91% (Rf = 0.35). FTIR (KBr, cm−1): 1607
1
=
(C N), 2874, 2910, 2963; H NMR (400 MHz, CDCl3): δ 1.03–1.06 (m, 6H), 1.74–1.81
(m, 4H), 3.07–3.11 (m, 4H), 4.09–4.13 (dd, J = 4.2, 12.1 Hz, 1H), 4.21–4.25 (dd, J = 4.8,
12.1 Hz, 1H), 4.35–4.48 (m, 4H), 4.30–4.34 (dd, J = 4.8, 12.1 Hz, 1H), 4.58–4.63 (dd,
J = 3.3, 12.1 Hz, 1H), 4.85–5.00 (m, 2H), 7.28 (d, J = 8.0 Hz, 2H), 7.43–7.47 (t, J = 7.5 Hz,
4H), 7.51 (s, 2H), 7.78 (d, J = 7.4 Hz, 4H); 13C NMR (100 MHz, CDCl3): δ 14.03, 14.10,
28.74, 28.83, 38.35, 38.47, 41.21, 43.25, 52.72, 54.83, 59.34, 60.89, 119.59, 124.78, 127.43,
127.86, 129.00, 146.99, 164.09 and 164.12 (C N); Anal. Calcd for C16H20N4S3: C, 52.72;
H, 5.53; N, 15.37. Found: C, 52.90; H, 5.68; N, 15.20.
=
Acknowledgement
We thank Dr B. Eftekhari-Sis for his comments about our article.
Disclosure statement
No potential conflict of interest was reported by the authors.
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