Features of reactions of (E)-1-(β-aroylvinyl)pyridinium bromides with binucleophiles

Article abstract of DOI:10.1134/S1070363216070070

Regardless of pH and a solvent nature the reactions of (E)-1-(β-aroylvinyl)pyridinium bromides with hydrazine led to the formation of pyrazole derivatives. The salts reacted with thiourea via intermediate formation of 4-arylpyrimidine-2-thiol to give (Z)-

Full text of DOI:10.1134/S1070363216070070

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 7, pp. 1574–1580. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © R.Dzh. Khachikyan, Z.G. Ovakimyan, G.A. Panosyan, R.A. Tamazyan, A.G. Ayvazyan, 2016, published in Zhurnal Obshchei
Khimii, 2016, Vol. 86, No. 7, pp. 1095–1101.
Features of Reactions of (E)-1-(β-Aroylvinyl)pyridinium
Bromides with Binucleophiles
R. Dzh. Khachikyan, Z. G. Ovakimyan, G. A. Panosyan,
R. A. Tamazyan, and A. G. Ayvazyan
Institute of Organic Chemistry, Scientific-Technological Center of Organic and Pharmaceutical Chemistry,
National Academy of Sciences, pr. Azatutyan 26, Yerevan, 0014 Armenia
e-mail: khachikyanraya@gmail.com
Received November 30, 2015
Abstract—Regardless of pH and a solvent nature the reactions of (E)-1-(β-aroylvinyl)pyridinium bromides
with hydrazine led to the formation of pyrazole derivatives. The salts reacted with thiourea via intermediate
formation of 4-arylpyrimidine-2-thiol to give (Z)-2-[(β-aroylvinyl)sulfanyl]-4-arylpyrimidines. In the case of
N,N'-diphenylthiourea the reaction provided 6-aryl-3-aroyl-1-phenylpyridinium bromides. Pyridine
hydrobromide liberated in the reaction course has a major influence on the process chemoselectivity.
Keywords: (E)-1-(β-aroylvinyl)pyridinium bromide, pyrimidine thiol, elimination, addition
DOI: 10.1134/S1070363216070070
(E)-β-Aroylacrylic acids and (E)-1-(β-aroylvinyl)-
pyridinium bromides 1a–1c [1] have been known to
react with hydroxylamine hydrochloride in different
ways [2]. Data on reactions of (E)-1-(β-aroylvinyl)-
pyridinium bromide 1a–1c with binucleophiles are
absent. In order to further functionalization of these
salts and to obtain new heterocyclic compounds we
studied their interaction with such binucleophiles as
hydrazine and thioureas.
proceed in a different manner. Thus, in alcohol or
acetic acid the reaction led to the formation of adducts
across the double bond, while in the presence of
sulfuric or hydrochloric acid hydrazones or pyrazo-
linecarboxylic acid derivatives formed [3, 4].
The reaction of (E)-1-(β-aroylvinyl)pyridinium
bromides 1a–1c with hydrazine hydrate and hydro-
chloride in aqueous acetonitrile or ethanol afforded
pyrazole derivatives. In the case of hydrazine hydro-
chloride the corresponding hydrochlorides were ob-
tained (Scheme 1).
Depending on the pH value of the medium the
reaction of β-aroylacrylic acids with hydrazine may
Scheme 1.
O
NH2NH2
NH2NH2 2HCl
+
R
N
−H2O
Br−
−H2O, HBr
N
N
N
R
N
H
3c
1а−1c
N NH2
Br−
R
R
+
+
N
N
N
N
N
Br−
−HBr
H
N
H
HCl
R
2а−2c
R = СН3 (а), Сl (b), Br (c).
1574

FEATURES OF REACTIONS OF (E)-1-(β-AROYLVINYL)PYRIDINIUM BROMIDES
1575
Scheme 2.
R
R
R
Br−
+N
Br−
+N
NH2CSNH2
+N
Br−
−H2O
O
N
O
NH
NH
H2N
1а−1c
S
S
R
R
R
S
N
1а−1c
O
S
N
N
N+
N
N
−HBr
Br−
SH
R
O
N
N
N
−HBr
R
4а−4c
R = СН3 (а), Сl (b), Br (c).
The reaction probably occurs via initial condensa-
tion of compounds 1a–1c with hydrazine involving the
carbonyl group followed by intramolecular nucleo-
philic addition of NH2 group across the double bond
with the elimination of pyridine. However, an
alternative reaction pathway including initial nucleo-
phile attack on the double bond should not be excluded.
and subsequent cleavage of pyridine. Prototropic iso-
merization leads to the formation of the intermediate
sulfanylpyrimidine, which adds the second molecule of
the original salt followed by elimination of pyridine
hydrobromide.
The reactions of N,N'-diphenylthiourea with the
salts 1a–1c resulted in the formation of 2-aryl-5-aroyl-
1-phenylpyridinium bromides 5a–5c, as well as
enamine ketones 6a–6c and 1-(phenylcarbamothioyl)-
pyridinium bromide 7 as the minor reaction products
(Scheme 3).
It has been found previously that depending on the
reaction temperature and the nature of the solvent and
the catalyst the reaction of (E)-β-aroylacrylic acids
with thiourea may provide salts of β-aroylacrylic acids
with thiourea, 2-iminothiazolidinone derivatives,
thiohydantoins, thiazolidinediones, and N,N'-sub-
stituted thioureas [5–7].
Most likely, the attack of N,N'-diphenylthiourea
takes place only at the double bond of the original salt
1, and the nitrogen atom is a nucleophilic site.
Subsequent cleavage of pyridine hydrobromide results
in the formation of intermediate A, which transforms
into compound B by attaching pyridine hydrobromide
at the C=S bond. Under the reaction conditions the
intermediate B eliminates aniline to form compound C
(pathway a) or is converted into enaminoketone 6 and
1-(phenylcarbamothioyl)pyridinium bromide 7 (path-
way b).
A different pattern was observed when reacting (E)-
1-(β-aroylvinyl)pyridinium bromides 1a–1c with
1
thiourea. According to H and 13C NMR data, in
acetonitrile and toluene the reaction led to the forma-
tion of (Z)-4-aryl-2-[(β-aroylvinyl)sulfanyl]pyrimi-
dines 4a–4c instead of the expected 1-hydro-2-sul-
fanylpyrimidine derivatives (Scheme 2).
The reaction presumably starts with the attack of
amino group at the double bond of salt 1, and then
condensation happens with the second amino group
Aminolysis of the intermediate C with aniline
(pathway c) and reacting the liberated aniline with the
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 7 2016

1576
KHACHIKYAN et al.
Scheme 3.
O
+
N
Br−
R
1
O
O
+
N
Br−
HBr
N
PhNHCSNHPh
N
C
S
NH
Ph
N
C
S
NH
Ph
Ph
Ph
H
−HBr
N
R
R
B
А
O
O
а
c
+
NH
Ph
+ 7
N
NH2
C
Ph
+
N
Br−
Ph
S
R
R
6
C
O
b
+
NH
+ NH
C
N
S Br−
Ph
Ph
R
6
7
R
R
d
+ H2NPh
+N
Br−
+N
Br−
O
O
HNPh
1
R
NH
Ph
−HBr
N
O
6
initial salts 1a–1c (pathway d) may also provide
compounds 6a–6c.
the intermediate enamines undergo rearrangement into
imines. Next, betaine intermediate carbanion attacks
electrophilic carbon atom in the α-position relative to
the pyridinium cation, followed by eliminating pyri-
dinium bromide. Subsequent dehydration results in the
formation of salts 5a–5c (Scheme 4).
The data obtained confirmed clearly that the forma-
tion of 2-aryl-5-aroyl-1-phenylpyridinium bromides
results from the reaction of β-aroylvinylanilines 6a–6c
with the original salts 1a–1c.
Aniline and compounds 6a–6c reacted with the
salts 1a–1c under the same conditions in a ratio of 2 : 1
and 1 : 1, respectively, that supported the proposed
reaction pathway.
As can be seen from the scheme below, compounds
6a–6c do react across the double bond, but at the
carbonyl group of the starting salts 1a–1c. Probably,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 7 2016

FEATURES OF REACTIONS OF (E)-1-(β-AROYLVINYL)PYRIDINIUM BROMIDES
1577
Scheme 4.
R
R
R
Ph
HN
Ph
N
Ph
N
R
R
+
O
O
+
HO
HO
Br−
−
Br−
Br−
N+
N+
O
N+
O
R
6а−6c
1а−1c
R
R
Ph
N+
R
Ph
N+
H
O
HO
R
−
HO
−HBr
N
−
Br−
N+
O
R
R
N
HBr
Ph
Ph
Br−
Br−
N+
R
N+
R
−H O,
N
2
HO
H
O
O
5а−5c
R = СН3 (а), Сl (b), Br (c).
Table 1. Yields, melting points and elemental analysis data of compounds 2–6
Found, %
Calculated, %
Comp.
no.
Yield, %
mp, °C
Formula
C
H
N
C
H
N (Br)
14.39
13.02
10.78
2а
2b
2c
69
73
75
168–169 61.72
202–203 50.19
170–171 41.65
5.60
3.77
2.98
14.38 C10H11ClN2
13.08 C9H8Cl2N2
10.73 C9H8BrClN2
61.69 5.65
50.23 3.72
41.61 3.08
4а
4b
4c
5а
5b
5c
6а
6b
6c
89
90
94
199–200 72.78
224–225 58.86
226–227 47.91
5.24
3.14
2.50
8.13 C21H18N2OS
7.22 C19H12N2Cl2OS 58.91 3.10
5.84 C19H12N2Br2OS 47.89 2.52
72.83 5.20
8.09
7.23
5.88
41 (а), 90 (b), 89 (c) 254–255 70.25 4.89 (18.00) 3.18 C26H22NOBr
43 (а) 220–221 61.39 3.47 (17.02) 2.95 C24H16NOBrCl2 61.41 3.41
46 (а), 86 (b), 91 (c) 230–231 49.97 2.66 (41.85) 2.41 C24H16NOBr3
70.27 4.95
3.15 (18.02)
2.99 (17.06)
2.44 (41.81)
5.91
50.17 2.79
81.01 6.33
69.90 4.66
59.60 3.97
17
11.5
7
81.05
69.79
58.98
6.30
4.71
4.01
4.96 C16H15NO
5.38 C15H12NOCl
4.56 C15H12NOBr
5.44
4.64
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 7 2016

1578
KHACHIKYAN et al.
Table 2. NMR spectral data (DMSO-d6–CCl4, 1 : 3) for compounds 2–6
Comp no.
δ, ppm (J, Hz)
2a
δН: 6.60 d (1H, H4, pyrazole, J = 2.2), 7.18–7.22 m (2H, C6H4), 6.62–7.75 m (1H, H5, pyrazole; 2H, C6H4), 9.00
br. S (2H, H1,2, pyrazole)
2b
2c
4a
δН: 6.60 d (1H, H4, pyrazole, J = 2.2), 7.33–7.38 m (2H, C6H4), 7.63 d (1H, H5, pyrazole, J = 2.2), 7.74–.79 m
(2H, C6H4), 8.68 br.s (2H, H1,2, pyrazole)
δН: 6.63 d (1H, H4, pyrazole, J = 2.2), 7.50–7.55 m (2H, C6H4), 7.64 d (1H, H5, pyrazole, J = 2.2), 7.78–7.80 m
(2H, C6H4), 9.20 br.s (2H, H1,2, pyrazole)
δН: 2.45 s (3H, CH3), 2.46 s (3H, CH3), 7.28–7.35 m (4H, C6H4), 7.42 d (1H, SCH=CH, J = 10.0), 7.72 d (1H,
CH=CHN, J = 5.3), 7.88–7.95 m (2H, C6H4), 8.07–8.13 m (2H, C6H4), 8.70 d (1H, CH=CHN, J = 5.3), 8.86 d
(1H, SCH=CH, J = 10.0)
δC: 20.9 (CH3), 21.0 (CH3), 113.2 (CH=CHN), 116.8 (SCH=CH), 126.8, 127.8, 128.8, 129.1, 132.5, 134.6,
141.0, 142.4, 142.5 (SCH=CH), 157.7 (CH=CHN), 163.4 168.4, 187.2 (CO).
4b
4c
5a
δН: 7.59–7.65 m (5H, C6H4 + pyrimidine), 7.98 d (1H, CH=CHN, J = 5.3), 7.08–8.12 m (2H, C6H4), 8.26–8.31 m
(2H, C6H4), 8.85 d (1H, CH=CHN, J = 5.3), 8.90 d (1H, SCH, J = 9.9)
δН: 7.53 d (1H, SCH=CH, J = 10.0), 7.68–7.74 m (4H, C6H4), 7.91 d (1H, CH=CHN, J = 5.3), 7.97–8.02 m (2H,
C6H4), 8.17–8.22 m (2H, C6H4), 8.80 d (1H, CH=CHN, J = 5.3), 8.90 d (1H, SCH=CH, J = 10.0)
δН: 2.36 s (3H, CH3), 2.50 s (3H, CH3), 7.15–7.20 m (2H, C6H4), 7.37–7.50 m (7H, C6H5 + C6H4), 7.76–7.80 m
(2H, C6H4), 8.02–8.06 m (2H, C6H4), 8.39 d (1H, C5H3N+, J = 8.2), 8.95 d.d (1H, C5H3N+, J = 8.2, 1.8), 9.19 d
(1H, C5H3N+, J = 1.8)
δC: 20.8 (CH3), 21.2 (CH3), 126.6, 128.6, 128.7, 128.8, 129.2, 129.7, 130.0, 130.3, 130.5, 132.3, 135.3, 140.4,
141.9, 144.5, 145.3, 146.9 (NCH), 156.9, 189.2 (CO)
5b
5c
δН: 7.37–7.42 m (2H, C6H4), 7.48–7.55 m (3H, C6H5), 7.65–7.70 m (4H, C6H5 + C6H4), 7.88–7.99 m (4H,
ClC6H4CO), 8.52 d (1H, C5H3N+, J = 8.2), 9.09 d.d (1H, C5H3N+, J = 8.2, 1.7), 9.60 d (1H, C5H3N+, J = 1.7)
δН: 7.35–7.40 m (2H, C6H4), 7.48–7.55 m (3H, C6H5), 7.61–7.65 m (2H, C6H5), 7.65–7.70 m (2H, C6H4), 7.87–
7.95 m (4H, BrC6H4CO), 8.51 d (1H, C5H3N+, J = 8.2), 9.07 d.d (1H, C5H3N+, J = 8.2, 1.8), 9.56 d (1H, C5H3N+,
J = 1.8)
6a
δН: 2.2 s (3H, CH3), 6.02 d (0.75H, =CHCO, J = 7.8), 6.37 d (0.25H, =CHCO, J = 12.5), 6.92 br.t (0.25H, Ph,
(Z : E =
3 : 1)
J
= 7.3), 7.02 br.t (0.75H, Ph, J = 7.3), 7.05–7.11 m (0.5H, Ar), 7.18–7.38 m (5.5H, Ar), 7.68 d.d
(0.75H, =CHN, J = 12.1, 8.0), 7.76–7.79 m (0.5H, Ar), 7.80–7.83 m (1.5H, Ar), 8.03 d.d (0.25H =CHN, J =
12.9, 12.5), 9.80 br.d (0.25H, NH, J = 12.9), 12.10 br.d (0.75H, NH, J = 12.1)
6b
δН: 6.10 d (0.7H, =CHCO, J = 7.8), 6.40 d (0.3H, =CHCO, J = 12.4), 7.04 br.t (0.3H, 4-H, Ph, J = 7.5), 7.12 br.t
(Z : E = (0.7H, 4-H, Ph, J = 7.5), 7.18–7.20 m (0.6H, Ar), 7.27–7.40 m (3.4H, Ar), 7.56–7.60 m (2H, Ar), 7.81–7.85 d.d
7 : 3)
(0.7H, =CHN, J = 12.5, 7.8), 7.84–7.87 m (0.6H, Ar), 7.87–8.00 m (1.4H, Ar), 8.13 d.d (0.3H, =CHN, J = 13.1,
12.4), 10.20 br.d (0.3H, NH, J = 13.1), 12.10 br.d (0.7H, NH, J = 12.4)
6c
δН: 6.02 d (0.7H, =CHCO, J = 7.8), 6.34 d (0.3H, =CHCO, J = 12.4), 6.95 br.t (0.3H, 4-H, Ph, J = 7.3), 7.04 br.t
(Z : E = (0.7H, 4-H, Ph, J = 7.3), 7.09–7.14 m (0.6H, Ar), 7.19–7.37 m (3.4H, Ar), 7.55–7.60 m (2H, Ar), 7.76 d.d (0.7H,
7 : 3)
=CHN, J = 12.4, 7.8), 7.77–7.81 m (0.6H, Ar), 7.81–7.86 m (1.4H, Ar), 8.11 d.d (0.3H, =CHN, J = 13.1, 12.4),
9.92 br.d (0.3H, NH, J = 13.1), 12.14 br.d (0.7H, NH, J = 12.4)
Structure of compounds obtained was established
molecules whose position with respect to each other is
characterized by an inversion pseudocenter (0.97 0.62
0.24), which is an apparent cause of twinning. All
cyclic fragments of compound 5a are planar. The
maximum deviation of the atoms from the average
plane of the benzene ring does not exceed 0.0092(2)
(Ph), 0.0051(3) (p-Tol), 0.0252(3) (Py) and 0.0210(2) Å
[4-CH3C(O)Ph].
1
by H and 13C NMR spectroscopy methods (Tables 1
and 2). Two-dimensional NOESY and HMQC
techniques were used for assigning signals.
Structure of compound 5a was confirmed by X-ray
diffraction analysis (see figure). As show XRD data
the unit cell contains two symmetrically nonequivalent
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 7 2016

FEATURES OF REACTIONS OF (E)-1-(β-AROYLVINYL)PYRIDINIUM BROMIDES
1579
Fig. 1. General view of the molecule of compound 5а in the crystal.
EXPERIMENTAL
~ 2 : 15). The coordinates of the hydrogen atoms were
determined by geometric calculations and refined in
a rider model, C–H = 0.93–0.96 Å, Uiso(H) = 1.2–
1.5Ueq(C). The structure was refined by full-matrix
least-squares method in anisotropic approximation for
nonhydrogen atoms and in isotropic approximation for
hydrogen atoms; the final divergence factors: R =
0.0708, wR2 = 0.1789, S = 1.02. All calculations were
performed using SHELXTL software [9]. The crys-
tallographic data were deposited at the Cambridge
Crystallographic Data Centre (CCDC 1,416,811).
1H and 13C NMR spectra were recorded on a Varian
Mercury-300 spectrometer (75.46 and 300.08 MHz,
respectively) at 303 K. Chemical shifts are with
respect to TMS signal.
Single-crystal X-ray diffraction measurements were
performed at room temperature on an automatic dif-
fractometer CAD-4 Enraf-Nonius (graphite monochro-
mator, MoKα-radiation, θ/2θ-scanning). Parameters of
the monoclinic unit cell measured and refined by 24
reflections in a scanning range of 11.07 < θ < 12.20
were as follows: a = 7.2250(14), b = 13.697(3), c =
22.058(4) Å, β = 99.11(3)°, V = 2155.3(8) Å3, space
group Pn, Z 4, crystal size 0.35 × 0.30 × 0.22 mm.
6727 independent reflections were measured in the
range of 0 ≤ h ≤10, 0 ≤ k ≤19, 0 ≤ l ≤ 30, θmax = 30°. An
array of experimental data contained 6727 sym-
metrically nonequivalent reflections, 3671 of them
with I > 2σ(I). Absorption was accounted by ψ-
scanning method [Tmin = 0.28996, Tmax = 0.33174,
μ(MoKα) = 1.924 mm–1] [8]. The structure was solved
by the direct method and refined as a inversion twin
(the ratio of volumes of the twin components of
(E)-1-(β-Aroylvinyl)pyridinium bromides 1a–1c
were synthesized as described in [1].
3-Aryl-1H-pyrazoles hydrochlorides (2a–2c). A
solution of 0.95 g (0.009 mol) of hydrazine hydro-
chloride in a minimum amount of water was added to a
saturated solution of 0.0015 mol of the salt 1a–1c in
acetonitrile (or ethanol). The reaction mixture was
refluxed for 30 h, then cooled and poured into 200 mL
of water. The reaction product was extracted with
chloroform and reprecipitated with diethyl ether. The
precipitate was filtered off, washed with ether, and
dried in a vacuum.
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1580
KHACHIKYAN et al.
3-(4-Bromophenyl)-1H-pyrazole (3c). A mixture
7.62–8.00 m (10H, Ph, Py). Found, %: C 48.89; H,
3.51; N 9.48; Br 27.34. C12H10BrN2S. Calculated, %: C
48.98; H 3.40; N 9.52; Br 27.21.
of 0.55 g (0.0015 mol) of 1-[(E)-3-(4-bromophenyl)-3-
oxoprop-1-en-1-yl]pyridinium bromide 1c in aceto-
nitrile and 0.44 mL (0.009 mol) of 65% hydrazine
hydrate was refluxed for 8 h. The reaction mixture was
poured into 100 mL of water, and the reaction product
was extracted with chloroform. After removing the
solvent, the residue was recrystallized from acetonitrile
and dried in a vacuum. Yield 0.26 g (73%), mp 135°C.
1H NMR spectrum (DMSO-d6–CCl4, 1 : 3), δ, ppm:
6.52 br.s (1Н, Н4, pyrazole), 7.42–7.60 m (3Н, C6H4 +
H5, pyrazole), 7.63‒7.74 m (2Н, C6H4), 12.74 br.s
(0.75Н, NH), 13.14 br.s (0.25Н, NH). Found N, %:
12.60. C9H7BrN2. Calculated N, %: 12.56.
b. A mixture of 0.001 mol of the salt 1a or 1c,
0.05 mL (0.0005 mol) of aniline, and 12.10 mL of
acetonitrile was refluxed for 15–17 h. Compounds 5a
and 5b were isolated as described above.
c. A mixture of 0.0005 mol of the salt 1a or 1c,
0.0005 mol of compound 6a or 6b, and 7.5 mL of
acetonitrile was refluxed for 14–15 h. The product was
isolated as described above.
β-Aroylvinylanilines (6a–6c).
A
mixture of
0.001 mol of salt 1a or 1c, 0.037 mL (0.004 mol) of
aniline and 0.2 mL (0.0001 mol) of 41% HBr solution
in 5–7 mL of ethanol was refluxed for 2–3 h. The
resulting precipitate was filtered off, washed with
alcohol, dried in a vacuum, and recrystallized from
acetonitrile.
(Z)-1-Aryl-3-[(4-arylpyrimidin-2-yl)sulfanyl] prop-
2-en-1-ones (4a–4c). A mixture of 0.0015 mol of salt
1a–1c, 0.1 g (0.0015 mol) of thiourea in 10 mL of
acetonitrile was heated for 17–20 h. The resulting
precipitate was filtered off, repeatedly washed with hot
acetonitrile, and dried in a vacuum.
REFERENCES
2-Aryl-5-aroyl-1-phenylpyridine bromides (5a–5c).
a. A mixture of 0.001 mol of salt 1a–1c, 0.23 g
(0.001 mol) of N,N'-diphenylthiourea, and 10–12 mL
of acetonitrile was refluxed for 17–20 h. After cooling,
the reaction mixture was filtered. The reaction product
was precipitated with diethyl ether from the filtrate.
The precipitate was filtered off, washed with diethyl
ether, and dried in a vacuum. The precipitate obtained
was additionally refluxed in benzene, filtered off,
washed thoroughly with hot benzene, and dried in a
vacuum.
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4. El’Kadi, M., El’Hashash, M.А., and Sayed, M.A., Rev.
Roum. Chem., 1981, vol. 26, no. 8, p. 1161.
Acetonitrile filtrate was evaporated, the residue was
recrystallized from acetonitrile to yield compound 6a–
6c as a mixture of Z,E-isomers in the ratio of 3 : 1, 7 : 3,
and 7 : 3, respectively.
5. Abgalyan, S.G. and Khachikian, R.Dzh., Arm. Khim.
Zh., 1981, vol. 34, no. 7, p. 569.
6. Khachikian, R.Dzh., Atashyan, S.M., and Agbalyan, S.G.,
Arm. Khim. Zh., 1984, vol. 37, no. 4, p. 237.
After recrystallization of compound 6a–6c, the
acetonitrile filtrate was evaporated. The residue was
dissolved in chloroform and reprecipitated with hexane
to give 0.05 g (17%) of 1-(phenylcarbamothioyl)pyri-
dinium bromide 7 of mp 89–90°C. H NMR spectrum
(DMSO-d6–CCl4, 1 : 3), δ, ppm: 9.80 br.s (1H, NH),
8. North, A.C.T., Phillips, D.C., and Mathews, F. S., Acta
Crystаllogr. (A),1968, vol. 24, p. 351. DOI: 10.1107/
S0567739468000707.
1
9. Sheldrick, G.M., Acta Crystallogr. (A), 2008, vol. 64,
p. 112. DOI: 10.1107/S0108767307043930.
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