Heterocyclization of 2-(Propargylsulfanyl)-1,3-thiazole Derivatives by the Action of Halogens

Article abstract of DOI:10.1134/S1070428018030156

Reactions of 2-(propargylsulfanyl)-5-methyl-1,3,4-thiadiazole, N-[5-(propargylsulfanyl)-1,3,4-thiadiazol- 2-yl]benzamide, 2-(propargylsulfanyl)-1,3-benzothiazole, and 2-(propargylsulfanyl)-4,5-dihydro-1,3- thiazole with iodine involved annulation of the u

Full text of DOI:10.1134/S1070428018030156

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2018, Vol. 54, No. 3, pp. 469–474. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © N.M. Tarasova, D.G. Kim, O.S. El’tsov, T.S. Shtukina, A.E. Borisova, 2018, published in Zhurnal Organicheskoi Khimii, 2018,
Vol. 54, No. 3, pp. 463–467.
Heterocyclization of 2-(Propargylsulfanyl)-1,3-thiazole
Derivatives by the Action of Halogens
N. M. Tarasovaa,* D. G. Kima, O. S. El’tsovb, T. S. Shtukinab, and A. E. Borisovaa
a South Ural State University, pr. im. Lenina 76, Chelyabinsk, 454071 Russia
*e-mail: tarasovanm@susu.ru
b Yeltsin Ural Federal University, ul. Mira 19, Yekaterinburg, 620002 Russia
Received July 5, 2017
Abstract—Reactions of 2-(propargylsulfanyl)-5-methyl-1,3,4-thiadiazole, N-[5-(propargylsulfanyl)-1,3,4-thia-
diazol-2-yl]benzamide, 2-(propargylsulfanyl)-1,3-benzothiazole, and 2-(propargylsulfanyl)-4,5-dihydro-1,3-
thiazole with iodine involved annulation of the unsaturated substituent with formation of fused thiazole ring.
2(5)-(Propargylsulfanyl)-1,3,4-thiadiazole derivatives reacted with bromine to give mixtures of heterocycliza-
tion products and bromine adducts to the triple bond. The bromination of 2-(propargylsulfanyl)-4,5-dihydro-
1,3-thiazole afforded only the bromine addition product to the triple bond.
DOI: 10.1134/S1070428018030156
Synthesis and properties of fused thiazolo[2,3-b]-
thiazolium and thiazolo[2,3-b][1,3,4]thiadiazolium
systems attract much attention due to their efficiency
as immune response modulators [1] and drugs for
thrombolytic therapy [2]. The known procedure for the
synthesis of these heterocyclic systems is based on
heterocyclization of phenacylsulfanyl derivatives of
1,3-thiazole, dihydro-1,3-thiazole, and 1,3-benzothia-
zole. However, this procedure often requires fairly
harsh conditions, in particular prolonged heating, and
the use of concentrated mineral acids [1].
kenylsulfanyl)-1,3,4-thiadiazoles, -1,3-benzothiazoles,
and -4,5-dihydro-1,3-thiazole at room temperature. In
this work we have studied reactions of 2-(propargyl-
sulfanyl)-1,3,4-thiadiazoles and -1,3-thiazoles with
iodine and bromine with the goal of obtaining thiazolo-
[2,3-b]thiazolium and thiazolo[2,3-b][1,3,4]thiadi-
azolium derivatives.
By reacting 5-methyl-1,3,4-thiadiazole-2-thione
(1a), 5-amino-1,3,4-thiadiazole-2-thione (1b), 1,3-ben-
zothiazole-2-thione (2), and 4,5-dihydro-1,3-thiazole-
2-thione (3) with propargyl bromide in ethanol or
propan-2-ol we obtained 2-methyl-5-(propargylsul-
fanyl)-1,3,4-thiadiazole (4a). 5-(propargylsulfanyl)-
1,3,4-thiadiazol-2-amine (4b), 2-(propargylsulfanyl)-
Dihydrothiazolo[2,3-b]thiazolium and dihydrothia-
zolo[2,3-b][1,3,4]thiadiazolium derivatives were syn-
thesized previously [3−5] by halocyclization of 2-(al-
Scheme 1.
H
N
R
AlkOH, NaOAlk
Y
Br
+
S
S
CH
CH
S
1a, 1b, 2, 3
4a, 4b, 5, 6
; 6, R =
N
S
N
S
N
N
4, R =
, R′ = Me (a), NH2 (b); 5, R =
.
R'
S
PhCOCl, Et3N
O
N
N
dioxane, 20°C
4b
Ph
N
CH
S
S
H
4c
469

TARASOVA et al.
470
Scheme 2.
I
I
I
H
H
H
(1) I2, EtOH (dioxane), 20°C, 48 h
(2) NaI, Me2CO
N
N
I–
N
N
I–
I–
4a, 4c, 5, 6
R
S
S
S
S
S
S
7a, 7b
7c
7d
R = Me (a), PhC(O)NH (b).
1,3-benzothiazole (5), and 2-(propargylsulfanyl)-4,5-
dihydro-1,3-thiazole (6), respectively. The acylation of
4b with benzoyl chloride afforded N-[5-(propargyl-
sulfanyl)-1,3,4-thiadiazol-2-yl]benzamide (4c)
zolo[2,3-b][1,3,4]thiadiazolium iodide (7b), respec-
tively (Scheme 2). The =CHI proton resonated in the
1H NMR spectra of 7a and 7b at δ 7.40 and 7.20 ppm,
respectively, and the =CHI carbon signal was observed
in their 13C NMR spectra at δC 71.8 and 70.6 ppm.
1
(Scheme 1). In the H NMR spectrum of all sulfides
4–6, the most upfield signal due to CH≡ proton was
located at δ 2.31−3.29 ppm. The mass spectra of all
propargyl derivatives showed ion peaks resulting from
elimination of the propargyl and propargylsulfanyl
fragments from the molecular ion.
The configuration of the exocyclic C=C double
bond in 7a was determined using two-dimensional
NMR experiment. The 6-H and =CHI signals in the
1H NMR spectrum of 7a were a doublet and a triplet,
respectively, with a coupling constant J of 3 Hz, and
1
the 2D H–1H NOESY spectrum of 7a showed a cor-
We were the first to study the reactions of com-
pounds 4a and 4c with iodine. These reactions in-
volved closure of 1,3-thiazole ring with formation of
5-(iodomethylidene)-2-methyl-5,6-dihydro[1,3]thia-
zolo[2,3-b][1,3,4]thiadiazolium iodide (7a) and 2-ben-
zoylamino-5-(iodomethylidene)-5,6-dihydro[1,3]thia-
relation between these protons, which indicated their
spatial proximity and hence Z configuration of the
exocyclic double bond (Fig. 1).
Regioselective cyclization of 2-(propargylsulfanyl)-
1,3-benzothiazole (5) by the action of iodine gave
I
H
NOE
N
N
6-H
I–
Me
=CHI
S
S
7a
δ, ppm
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
6-H
=CHI
8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 δ, ppm
Fig. 1. 1H–1H NOESY spectrum of 5-(iodomethylidene)-2-methyl-5,6-dihydro[1,3]thiazolo[2,3-b][1,3,4]thiadiazol-4-ium iodide (7a).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 3 2018

HETEROCYCLIZATION OF 2-(PROPARGYLSULFANYL)-1,3-THIAZOLE DERIVATIVES
471
Scheme 3.
Br
H
(1) Br2, 0°C (20 min), 20°C (24–48 h)
(2) Me2CO
Br
N
S
N
S
H
4a, 4c
+
N
N
Br–
R
R
S
S
Br
8a, 8b
9a, 9b
Br
H
(1) Br2, CH2Cl2 –78°C (30 min), 20°C (72 h)
(2) Me2CO
5
N
Br–
S
S
10
Br
(1) Br2, 0°C (20 min), 20°C (48 h)
(2) Me2CO
H
N
6
S
S
Br
11
R = Me (a), PhC(O)NH (b).
3-(iodomethylidene)-2,3-dihydrobenzo[1,3]thiazolo-
[2,3-b][1,3]benzothiazolium iodide (7c). The presence
of a fused benzene ring induced downfield shift of all
were a doublet and a triplet, respectively, due to long-
range coupling with each other (as in the spectra of
compounds 7a–7d).
1
proton signals in the H NMR spectrum of 7c com-
3-(Bromomethylidene)-2,3-dihydro[1,3]thiazolo-
[2,3-b][1,3]benzothiazolium bromide (10) was ob-
tained by reaction of sulfide 5 with bromine in
methylene chloride on cooling to –78°C (Scheme 3).
No heterocyclization product was formed when the
reaction of 5 with bromine was carried out at 0°C.
pared to 7a and 7b, and the =CHI signal of 7c was
located at δ 8.00 ppm. Likewise, 2-(propargylsul-
fanyl)-4,5-dihydro-1,3-thiazole (6) reacted with iodine
to form 3-(iodomethylidene)-2,3,5,6-tetrahydro[1,3]-
thiazolo[2,3-b][1,3]thiazolium iodide (7d) (Scheme 2).
The reactions of 4a, 4c, 5, and 6 with bromine were
less selective due to concurrent bromine addition to the
triple bond. In the reaction with 4a, the corresponding
heterocyclization product, 5-(bromomethylidene)-2-
methyl-5,6-dihydro[1,3]thiazolo[2,3-b][1,3,4]thiadi-
azolium bromide (8a) was isolated in 38% yield. After
separation of 8a, the solution contained 2-(2,3-di-
bromoprop-2-en-1-ylsulfanyl)-5-methyl-1,3,4-thiadi-
azole (9a) which was identified by GC/MS. Compound
4c reacted with bromine in dioxane to give a mixture
of 2-benzamido-5-(bromomethylidene)-5,6-dihydro-
[1,3]thiazolo[2,3-b][1,3,4]thiadiazolium bromide (8b)
and N-[5-(2,3-dibromoprop-2-en-1-ylsulfanyl)-1,3,4-
thiadiazol-2-yl]benzamide (9b) at a ratio of 5:2 with
an overall yield of 54%. Compound 8b was also ob-
tained in 36% yield by reaction of 4c with bromine in
methylene chloride (Scheme 3).
The bromination of 2-(propargylsulfanyl)-4,5-dihy-
dro-1,3-thiazole (6) in glacial acetic acid or in dioxane
at 0°C afforded 2-(2,3-dibromoprop-2-en-1-ylsul-
fanyl)-4,5-dihydro-1,3-thiazole (11) (Scheme 3). As in
1
the H NMR spectra of bromine addition products 9a
and 9b, the SCH2 and =CHBr protons of 11 resonated
as singlets. The reaction direction did not change when
the reaction temperature was lowered to –78°C. Pre-
sumably, the nitrogen atom in the dihydrothiazole ring
is more basic than in aromatic analogs and is efficient-
ly solvated by solvent molecules, which makes it
inaccessible for heterocyclization and favors electro-
philic addition of bromine to the triple bond. The mass
spectrum of 11 contained [M – Br]+ ion peak with
m/z 236/238 and [CH2CHBr=CHBr]+ ion peak with
m/z 197/199/201.
1
In the H NMR spectrum of 9b, the =CHBr proton
EXPERIMENTAL
resonated at δ 7.15 ppm, which is typical of analogous
dibromoalkenes [6]. The =CHBr signal of 8b was
observed in a weaker field, at δ 7.24 ppm. The 6-H and
1
The H NMR spectra were recorded on Bruker
DRX-400 (400 MHz) and Bruker Avance 500
(500 MHz) spectrometers using tetramethylsilane as
1
=CHBr signals in the H NMR spectra of 8a and 8b
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 3 2018

TARASOVA et al.
472
internal standard. Two-dimensional H–1H NOESY
experiments were carried out on a Bruker Avance II
spectrometer (400 MHz, TMS). The mass spectra
(electron impact, 70 eV) were obtained on a Shimadzu
GCMS QP-2010 Ultra instrument (ion peaks with
a relative intensity of less than 5% were taken into
account for key molecular fragments). The elemental
compositions were determined with a Carlo Erba
CHNS-O EA 1108 analyzer. The melting points were
measured on a PTP (M) melting point apparatus. The
solvents used were preliminarily distilled; ethanol was
dried over CaO; dioxane was refluxed over alkali,
dried, and distilled over metallic sodium.
1
N-[5-(Prop-2-yn-1-ylsulfanyl)-1,3,4-thiadiazol-2-
yl]benzamide (4c). Compound 4b, 0.60 g (3.4 mmol),
was dissolved in 10 mL of dioxane, 1.21 mL
(3.4 mmol) of triethylamine and 0.58 mL (3.4 mmol)
of benzoyl chloride were added, and the mixture was
stirred for 12 h at room temperature. The precipitate
was filtered off, the solvent was distilled off from
the filtrate, and the residue was recrystallized from
ethanol. Yield 0.49 g (52%), white solid, mp 198–
1
200°C. H NMR spectrum (DMSO-d6), δ, ppm: 3.36 t
(1H, ≡CH, J = 2.5 Hz), 4.11 d (2H, SCH2, J = 2.6 Hz),
7.55–7.60 m (2H, Harom), 7.65–7.70 m (1H, Harom),
8.12–8.15 m (2H, Harom), 13.19 br.s (1H, NH).
13C NMR spectrum (DMSO-d6), δC, ppm: 8.9, 22.6,
45.9, 75.6, 79.9, 128.9, 129.1, 131.7, 133.5, 157.9,
160.9, 165.7. Found, %: C 52.32; H 3.31; N 15.22.
C12H9N3OS2. Calculated, %: C 52.34; H 3.29; N 15.26.
Compounds 4a, 4b, 5, and 6 (general procedure).
An equimolar amount of propargyl bromide was added
to a solution of 8 mmol of compound 1a, 16 mmol of
1b, 40 mmol of 2, or 10 mmol of 3 in 20 mL of ethanol
or propan-2-ol, and the mixture was stirred for 12–
20 h. The precipitate of NaBr was filtered off, and the
filtrate was evaporated. In the synthesis of 4a, 5, and 6,
the residue was treated with diethyl ether (3×10 mL),
the extracts were combined and filtered, and the filtrate
was evaporated. Compound 4b was isolated by recrys-
tallization from propan-2-ol.
2-(Prop-2-yn-1-ylsulfanyl)-1,3-benzothiazole (5).
1
Yield 4.71 g (55%), yellow viscous liquid. H NMR
spectrum (CDCl3), δ, ppm: 3.31 t (1H, ≡CH, J =
2.64 Hz), 4.26 (2H, SCH2, J = 7.31 Hz), 7.39 (1H,
Harom), 7.49 m (1H, Harom), 7.90 m (1H, Harom), 8.06 m
(1H, Harom). Mass spectrum, m/z (Irel, %): 205 (100)
[M]+, 204 (40) [M – H]+, 173 (16) [M – S]+, 172 (11)
[M – SH]+, 166 (23) [M – C3H3]+, 161 (14) [M – CS]+,
160 (11), 139 (5), 135 (7), 129 (20), 122 (17), 108 (37)
[C6S]+·, 102 (12), 82 (7), 71 (5), 70 (5), 69 (15), 63 (9),
45 (8), 39 (12). Found, %: C 58.48; H 3.51; N 6.79.
C10H7NS2. Calculated, %: C 58.50; H 3.44; N 6.82.
2-Methyl-5-(prop-2-yn-1-ylsulfanyl)-1,3,4-thiadi-
azole (4a). Yield 0.94 g (69%), yellow viscous liquid.
1H NMR spectrum (CDCl3), δ, ppm: 2.31 t (1H, CH≡,
J = 2.6 Hz), 2.76 s (3H, 2-CH3), 4.04 d (2H, SCH2, J =
2.6 Hz). 13C NMR spectrum (CDCl3), δC, ppm: 17.5,
42.1, 99.6, 137.8, 172.7, 181.97. Mass spectrum, m/z
(Irel, %): 170 (16) [M]+, 169 (<5) [M – H]+, 137 (<5)
[M – SH]+, 131 (9) [C4H5NS2]+, 129 (100) [C4H3NS2]+,
128 (5), 102 (8), 96 (5), 90 (6), 85 (13), 76 (9), 73 (7),
72 (7), 71 (79) [C3H3S]+, 70 (14), 69 (11), 59 (56)
[C2H3S]+, 58 (17), 45 (21) [C3H3]+, 42 (5), 39 (45).
Found, %: C 42.15; H 3.58; N 16.54. C6H6N2S2. Cal-
culated, %: C 42.35; H 3.53; N 16.47.
2-(Prop-2-yn-1-ylsulfanyl)-4,5-dihydro-1,3-thia-
zole (6). Yield 1.04 g (66%), yellow viscous liquid.
1H NMR spectrum (CDCl3), δ, ppm: 2.26 t (1H, ≡CH,
J = 2.65 Hz), 3.44 t (2H, 5-H, J = 7.98 Hz), 3.88 d
(2H, SCH2, J = 2.65 Hz), 4.24 t (2H, NCH2, J =
7.98 Hz). Mass spectrum, m/z (Irel, %): 157 (13) [M]+·,
156 (100) [M – H]+, 131 (6) [M – C2H2]+·, 129 (54)
[M – C2H4]+·, 124 (<5) [M – SCH3]+, 97 (5), 85 (15)
[M – C3H3S]+, 81 (15), 80 (16), 72 (52) [C3H4S]+·, 71
(28) [C3H3S]+, 70 (10), 69 (10), 61 (7), 60 (59)
[SC2H4]+·, 59 (48) [SC2H3]+, 58 (14), 54 (11), 49 (10),
45 (43), 39 (30). Found, %: C 45.78; H 4.54; N 8.90.
C6H7NS2. Calculated, %: C 45.83; H 4.49; N 8.91.
5-(Prop-2-yn-1-ylsulfanyl)-1,3,4-thiadiazol-2-
amine (4b). Yield 1.89 g (68%), white powder,
mp 115–116°C. H NMR spectrum (CDCl3), δ, ppm:
1
3.29 t (1H, ≡CH, J = 2.5 Hz), 3.89 d (2H, SCH2, J =
2.5 Hz), 7.40 br.s (2H, NH2). 13C NMR spectrum
(CDCl3), δC, ppm: 23.3, 75.5, 80.1, 148.8, 170.9. Mass
spectrum, m/z (Irel, %): 171 (26) [M]+, 170 (<5%)
[M – H]+, 132 (4) [M – C3H3]+, 131 (9) [M – C3H3 – H]+,
130 (7), 128 (100) [C4H2NS2]+, 102 (6), 85 (6), 74
(8), 71 (60) [C3H3S]+, 70 (8), 69 (7), 60 (53), 59 (5),
45 (18) [C3H3]+, 39 (50). Found, %: C 35.02; H 2.88;
N 24.60. C5H5N3S2. Calculated, %: C 35.07; H 2.94;
N 24.54.
Compounds 7a–7d (general procedure). A solution
of 0.18 g (1 mmol) of compound 4a in 5 mL of
ethanol, or 0.2 g (0.7 mmol) of 4c in 10 mL of di-
oxane, or 1 g (5 mmol) of 5 in 20 mL of ethanol, or
0.2 g (1 mmol) of 6 in 5 mL of ethanol was added to
a solution of 2 equiv of iodine in 5 mL of ethanol or
dioxane. The mixture was stirred for 24–72 h at room
temperature, the solvent was evaporated, and the resi-
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HETEROCYCLIZATION OF 2-(PROPARGYLSULFANYL)-1,3-THIAZOLE DERIVATIVES
473
due was treated with excess sodium iodide in acetone.
The yellow precipitate was filtered off and washed
with 20 mL of acetone.
solvent over a period of 20 min. The mixture was
stirred for 24–72 h at room temperature and was then
treated as indicated below.
5-(Iodomethylidene)-2-methyl-5,6-dihydro[1,3]-
thiazolo[2,3-b][1,3,4]thiadiazol-4-ium iodide (7a).
Yield 0.25 g (59%), mp 197–199°C (decomp.).
1H NMR spectrum (DMSO-d6), δ, ppm: 2.78 s (3H,
CH3), 4.63 d (2H, 6-H, J = 3.0 Hz), 7.38 t (1H, =CHI,
5-(Bromomethylidene)-2-methyl-5,6-dihydro-
[1,3]thiazolo[2,3-b][1,3,4]thiadiazol-4-ium bromide
(8a). After 24 h, the solvent was removed, the residue
was treated with acetone, and the white solid was
filtered off and washed with 10 mL of acetone. Yield
13
1
J = 2.9 Hz). C NMR spectrum (DMSO-d6), δC, ppm:
0.1 g (38%), mp 298–300°C. H NMR spectrum
17.5, 45.0, 71.8, 139.9, 172.5, 180.9. Found, %:
C 16.95; H 1.49; N 6.62. C6H6I2N2S2. Calculated, %:
C 16.99; H 1.43; N 6.61.
(DMSO-d6), δ, ppm: 2.78 s (3H, CH3), 4.70 d (2H,
6-H, J = 3.3 Hz), 7.48 t (1H, =CHBr, J = 3.3 Hz).
13C NMR spectrum (DMSO-d6), δC, ppm: 17.4,
42.0, 99.5, 137.8, 172.7, 181.9. Found, %: C 21.74;
H 2.01; N 8.54. C6H6Br2N2S2. Calculated, %: C 21.83;
H 1.83; N 8.49.
2-Benzamido-5-(iodomethylidene)-5,6-dihydro-
[1,3]thiazolo[2,3-b][1,3,4]thiadiazol-4-ium iodide
(7b). Yield 0.28 g (76%), mp 201–203°C (decomp.).
1H NMR spectrum (DMSO-d6), δ, ppm: 4.65 d (2H,
6-H, J = 3.1 Hz), 7.22 t (1H, =CHI, J = 3.1 Hz), 7.59 t
(2H, Harom, J = 6.4 Hz), 7.66–7.76 m (2H, Harom),
8.13 d (1H, Harom, J = 7.2 Hz), 13.20 br.s (1H, NH).
13C NMR spectrum (DMSO-d6), δC, ppm: 43.9, 66.8,
70.6, 129.1, 129.3, 131.6, 132.2, 134.1, 140.9, 165.2,
168.9, 174.1. Found, %: C 27.19; H 1.74; N 7.92.
C6H6I2N2S2. Calculated, %: C 27.24; H 1.71; N 7.94.
2-(2,3-Dibromoprop-2-en-1-ylsulfanyl)-5-meth-
yl-1,3,4-thiadiazole (9a). Mass spectrum (filtrate), m/z
(Irel, %): 251 (100) [M – Br]+, 249 (99) [M – Br]+, 201
(5) [CH2CHBr=CHBr]+, 199 (12) [CH2CHBr=CHBr]+,
197 (6) [CH2CHBr=CHBr]+, 175 (20), 173 (22), 172
(7), 171 (9), 170 (76), 149 (5), 133 (10), 132 (14), 129
(41), 119 (10), 117 (11), 107 (5), 105 (5), 102 (5), 99
(7), 97 (5), 87 (18), 85 (9), 83 (7), 73 (42), 71 (21), 70
(8), 61 (5), 60 (9), 59 (47), 58 (13), 57 (14), 56 (7).
3-(Iodomethylidene)-2,3-dihydro[1,3]thiazolo-
[2,3-b][1,3]benzothiazol-4-ium iodide (7c). Yield
2.50 g (54%), mp 224–226°C (decomp.). H NMR
2-Benzamido-5-(bromomethylidene)-5,6-dihy-
dro[1,3]thiazolo[2,3-b][1,3,4]thiadiazolium bromide
(8b) and N-[5-(2,3-dibromoprop-2-en-1-ylsulfanyl)-
1,3,4-thiadiazol-2-yl]benzamide (9b). a. After 48 h,
the solvent was removed, the residue was treated with
acetone, and the yellow solid was filtered off and
washed with 10 mL of acetone. The product, 0.21 g
(54%), was a mixture of compounds 8b and 9b.
A 0.1-g portion of that mixture was heated for 10 min
in 5 mL of propan-2-ol under reflux; after cooling, the
white solid (8b) was filtered off. Yield 0.03 g (25%),
1
spectrum (DMSO-d6), δ, ppm: 4.79 d (2H, 2-H, J =
2.9 Hz), 7.72 m (2H, Harom), 8.00 t (1H, =CHI, J =
2.9 Hz), 8.39 d (1H, Harom, J = 7.8 Hz), 8.53 d (1H,
H
arom, J = 8.4 Hz). 13C NMR spectrum (DMSO-d6), δC,
ppm: 47.7, 66.8, 75.4, 115.9, 125.6, 127.2, 127.9,
129.6, 133.9, 140.6. Found, %: C 26.12; H 1.59;
N 3.13. C10H7I2NS2. Calculated, %: C 26.16; H 1.54;
N 3.05.
3-(Iodomethylidene)-2,3,5,6-tetrahydro[1,3]thia-
1
mp 188°C (decomp.). H NMR spectrum (DMSO-d6),
zolo[2,3-b][1,3]thiazol-4-ium iodide (7d). Yield
1
δ, ppm: 8b: 4.73 d (2H, 6-H, J = 3.2 Hz), 7.24 t (1H,
=CHBr, J = 3.2 Hz), 7.53–7.78 m (3H, Harom), 8.13 t
(2H, Harom, J = 7.1 Hz), 13.18 br.s (1H, NH);
9b: 4.37 d (2H, SCH2, J = 3.2 Hz), 7.15 s (1H, CHBr),
7.53–7.78 m (3H, Harom), 8.13 t (2H, Harom, J = 7.1 Hz),
13.18 br.s (1H, NH).
0.27 g (51%), mp 134–136°C (decomp.). H NMR
spectrum (DMSO-d6), δ, ppm: 4.09 d.d (2H, 6-H, J =
9.5, 7.7 Hz), 4.29 d.d (2H, 5-H, J = 9.6, 7.7 Hz), 4.66 d
(2H, 2-H, J = 2.9 Hz), 6.80 t (1H, =CHI, J = 2.9 Hz).
13C NMR spectrum (DMSO-d6), δC, ppm: 37.8, 47.4,
50.3, 141.9, 196.1. Found, %: C 17.23; H 1.84; N 3.37.
C6H7I2NS2. Calculated, %: C 17.53; H 1.72; N 3.41.
Compound 8b. b. A solution of 0.02 mL (0.3 mmol)
of bromine in 5 mL of methylene chloride was added
over a period of 30 min with stirring and cooling with
ice to a solution of 0.08 g (0.2 mmol) of compound 4c
in 10 mL of methylene chloride. After 10 days, the
yellow solid was filtered off and washed on a filter
with 10 mL of acetone. Yield 0.04 g (36%), mp 188°C
Bromination of compounds 4a, 4c, and 6 (general
procedure). To a solution of 0.13 g (0.8 mmol) of
compound 4a in 20 mL of methylene chloride, or
0.25 g (0.9 mmol) of 4c in 10 mL of dioxane, or 0.21 g
(1 mmol) of 6 in 10 mL of glacial acetic acid (or
dioxane) we added with stirring and cooling with ice
a solution of 1.5 equiv of bromine in 5 mL of the same
13
(decomp.). C NMR spectrum (DMSO-d6), δC, ppm:
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 3 2018

TARASOVA et al.
474
40.5, 61.95, 98.3, 128.7, 128.8, 128.9, 130.59, 133.8,
138.1, 164.2, 167.99, 174.9. Found, %: C 33.10;
H 2.11; N 9.71. C6H7Br2NS2. Calculated, %: C 33.12;
H 2.08; N 9.66.
and for 72 h at room temperature. The yellow solid
was filtered off and washed with 10 mL of methylene
chloride and acetone (3×10 mL). Yield 0.23 g (58%),
1
mp 295–297°C. H NMR spectrum (DMSO-d6), δ,
ppm: 4.87 d (2H, 2-H, J = 2.8 Hz), 7.68–7.79 m (2H,
2-(2,3-Dibromoprop-2-en-1-ylsulfanyl)-4,5-dihy-
dro-1,3-thiazole (11). a. After 48 h, the solvent was
removed, the residue was treated with acetone, and the
yellow solid was filtered off and washed with 10 mL of
acetone. Yield 0.29 g (78%), mp 135–137°C.
H
H
arom), 8.04 t (1H, =CHBr, J = 2.8 Hz), 8.39 d.d (1H,
arom, J = 1.1, 7.7 Hz), 8.49 d (1H, Harom, J = 8.2 Hz).
13C NMR spectrum (DMSO-d6), δC, ppm: 44.2, 101.6,
116.1, 155.7, 127.9, 129.4, 130.9, 133.9, 135.9, 140.4.
Found, %: C 32.89; H 2.12; N 3.80. C6H7Br2NS2. Cal-
culated, %: C 32.90; H 1.93; N 3.84.
b. Compound 11 was synthesized from 0.25 g
(1.6 mmol) of sulfide 6 in 20 mL of dioxane. After
72 h, the yellow solid was filtered off and washed with
dioxane (3 ×5 mL). Yield 0.43 g (84%), mp 135–
This study was performed under financial support
by the Government of the Russian Federation
(resolution no. 211, Mar 16, 2013; contract
no. 02.A03.21.0011) and in the framework of state
assignment of the Ministry of Education and Sciences
of the Russian Federation (project no. 4.9665.2017/8.9).
1
136°C. H NMR spectrum (DMSO-d6), δ, ppm: 3.53 t
and (2H, 5-H, J = 8.1 Hz), 4.17 t (2H, 4-H, J =
8.1 Hz), 4.41 s (2H, SCH2), 7.15 s (1H, =CHBr). Mass
spectrum, m/z (Irel, %): 238/236 (60/61) [M – Br]+,
201/199/197 (63/100/86) [CH2CHBr=CHBr]+, 157 (9),
118 (15), 82 (14), 81 (6), 72 (19), 71 (6), 61 (6), 60
(23), 59 (14), 45 (10), 44 (5), 43 (7), 42 (5), 39 (11).
Found, %: C 22.81; H 2.18; N 4.45. C6H7Br2NS2. Cal-
culated, %: C 22.73; H 2.23; N 4.42.
REFERENCES
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