Synthesis and molecular structure of 1-(Pyrimidin-2-yl)-2-(4-aryl-1,3- thiazol-2-yl)hydrazines

Article abstract of DOI:10.1134/S1070363211080196

Reactions of some 2-hydrazinopyrimidine hydrochlorides with potassium thiocyanate gave 1-(pyrimidin- 2-yl)thiosemicarbazides which underwent Hantzsch condensation with aryl chloromethyl ketones to produce 1-(pyrimidin-2-yl)-2-(4- aryl-1,3-thiazol-2-yl)hydrazine hydrochlorides. The protonation was accompanied by mutually dependent tautomeric rearrangements of heterocyclic fragments. Pleiades Publishing, Ltd., 2011.

Full text of DOI:10.1134/S1070363211080196

ISSN 1070-3632, Russian Journal of General Chemistry, 2011, Vol. 81, No. 8, pp. 1699–1704. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.V. Erkin, V.I. Krutikov, 2011, published in Zhurnal Obshchei Khimii, 2011, Vol. 81, No. 8, pp. 1354–1359.
Synthesis and Molecular Structure
of 1-(Pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazines
A. V. Erkin and V. I. Krutikov
St. Petersburg State Institute of Technology, Moskovskii pr. 26, St. Petersburg, 190013 Russia
e-mail: kruerk@yandex.ru
Received November 29, 2010
Abstract—Reactions of some 2-hydrazinopyrimidine hydrochlorides with potassium thiocyanate gave 1-(pyri-
midin-2-yl)thiosemicarbazides which underwent Hantzsch condensation with aryl chloromethyl ketones to
produce 1-(pyrimidin-2-yl)-2-(4-aryl-1,3-thiazol-2-yl)hydrazine hydrochlorides. The protonation was accom-
panied by mutually dependent tautomeric rearrangements of heterocyclic fragments.
DOI: 10.1134/S1070363211080196
1-(Pyrimidin-2-yl)thiosemicarbazides I are repres-
ented by a series of 4-aryl derivatives which were
synthesized by condensation of 2-hydrazinopyri-
midines with aryl isothiocyanates [1] and used mostly
for the preparation of arylamino[1,2,4]triazolo[4,3-a]-
or -[1,5-a]pyrimidines [2]. Presumably, the only
example of synthesis of compounds I with an un-
substituted carbothioamide group is preparation of 1-
(6-methyl-4-oxo-3,4-dihydropyrimidin-2-yl)thiosemi-
carbazide (IIa) from 2-hydrazino-6-methylpyrimidin-4
(3H)-one hydrochloride (IIIa) and potassium
thiocyanate [3]. However, compound IIa and its
analogs attract some interest as intermediate products
for the synthesis of previously unknown 1-(pyrimidin-
2-yl)-2-(1,3-thiazol-2-yl)hydrazines; particular frag-
ments of the latter are structural units of medical
agents inhibiting growth of human immunodeficiency
viruses [4].
toward aromatic α-halo ketones under the Hantzsch
reaction conditions and determining the structure of
the products. Compounds IIa and IIb were syn-
thesized by reaction of 2-hydrazinopyrimidin-4(3H)-one
hydrochlorides IIIa and IIIb with potassium
thiocyanate in water at 25°C, and initial hydro-
chlorides IIIa and IIIb were prepared by treatment of
free bases IVa and IVb with excess concentrated
hydrochloric acid at 25°C, followed by distillation of
water from the reaction mixture. Although 2-
hydrazinopyrimidinones like IVa and IVb are fairly
stable to acid hydrolysis with formation of the
corresponding pyrimidine-2,4(1H,3H)-diones [5],
water was removed under reduced pressure at a
temperature not exceeding 50°C. Crystallization of the
still residue from ethanol gave chromatographically
pure hydrochlorides IIIa and IIIb. It should be noted
that purification of compound IIIa according to the
above procedure gives a sample with reduced melting
point, indicating instability of hydrochloride IIIa on
heating in hydroxyl-containing medium.
The present work was aimed at studying the
reactivity of the carbothioamide group in 1-(4-oxo-3,4-
dihydropyrimidin-2-yl)thiosemicarbazides IIa and IIb
O
O
O
R
R
R
N
N
N
HCl
KSСN
Cl−
Me
H
H3N+
H2N
N
H2N
N
H
N
Me
N
N
Me
N
N
H
H
S
IIа, IIb
IVа, IVb
IIIа, IIIb
R = H (a), Me (b).
1699

1700
ERKIN, KRUTIKOV
The IR specta of IIIa and IIIb contained a
azeotrope (method a) resulted in the formation of the
expected Hantzsch product, 6-methyl-2-(4-phenyl-1,3-
thiazol-2-ylhydrazino)-3,4-dihydropyrimidin-4-one (VI),
broadened composite absorption band with several
maxima in the region 3500–2500 cm–1, which
originates from stretching vibrations of free,
associated, and protonated NH groups. We failed to
distinguish absorption bands due to bending vibrations
of amino groups, for they were obscured by stronger
and somewhat broadened carbonyl stretching vibration
bands in the region 1750–1650 cm–1. Insofar as
detection of individual absorption of the carbothio-
amide group in the IR spectra [6] was difficult, the
presence of such group in molecules IIa and IIb was
confirmed by liberation of sulfur dioxide from aqueous
solutions of these compounds upon treatment with a
solution of potassium permanganate.
1
which was identified by the H NMR spectrum con-
taining singlets from the methyl group at δ 2.2 ppm, 5-
H in the thiazole ring at δ ~6.9 ppm, and NH protons
in the hydrazine fragment at δ 7.8 ppm (intensity ratio
3:1:2). However, we failed to purify compound VI
from unidentified impurity (which gave rise to signals
in the region δ 0.8–5.0 ppm) even by repeated crystal-
lization from acetonitrile–dimethyl-formamide.
When the reactants (compounds IIa and Va) were
heated at 100°C in the absemce of a solvent (method
b), a new compound was formed with an Rf value
different from that of initial thiosemicarbazide IIa [Rf
0.90 (A)]. This compound decomposed during
crystallization from nitromethane–ethanol mixtures
with different compositions and was partially con-
verted into a dark red tarry material.
1
Compounds IIa and IIb displayed in the H NMR
spectra singlets from protons in the 6-methyl groups
and 5-H at δ 2.1–2.3 and 5.5–5.8 ppm, respectively
and degenerate signal from NH protons as a broadened
singlet in the region δ 8–9 ppm; the intensity of the
latter signal corresponded to five (IIa) or four protons
(IIb).
Unlike compound IIa, its N-methyl-substituted
analog IIb reacted with phenacyl chloride (method a)
to give 3,6-dimethyl-2-(4-phenyl-1,3-thiazol-2-ylhyd-
razino)-3,4-dihydropyrimidin-4-one hydrochloride (VIIa)
which was isolated as spectrally pure substance by
recrystallization. Replacement of butan-1-ol by ethanol
and reduction of the reaction temperature to 70°C led
to poor yield of VIIa (10%).
The reactions of compounds IIa and IIb with aryl
chloromethyl ketones Va–Vc were not selective.
1
According to the H NMR data, heating of pyrimidi-
nylthiosemicarbazide IIa with phenacyl chloride in
butan-1-ol with simultaneous removal of water as
O
Me
N
Ar
H
HCl
Cl
+
IIb
N
S
O
N
N
Me
H
N
Ar
Vа_Vc
VIIа_VIIc
Ar = Ph (a), 4-ClC6H4 (b), 3,4-(HO)2C6H3 (c).
R
Like phenacyl chloride, other aryl chloromethyl
ketones Vb and Vc reacted with pyrimidinylthio-
semicarbazide IIb; in the reaction with ketone Vb, 2-
[4-(4-chlorophenyl)-1,3-thiazol-2-ylhydrazino]-3,6-di-
methyl-3,4-dihydropyrimidin-4-one hydrochloride
(VIIb) was obtained (method b), and the reaction with
Vc afforded 2-[4-(3,4-dihydroxyphenyl)-1,3-thiazol-2-
ylhydrazino]-3,6-dimethyl-3,4-dihydropyrimidin-4-one
hydrochloride (VIIc) (method a). Purification of
compound VIIc by recrystallization gave 1:1 solvate
with DMF, whose structure is shown below.
O
H
O
NH
HN
H
O
N
H
NMe2
S
R = 3,6-dimethyl-4-oxo-3,4-dihydropyrimidin-2-yl.
The formation of solvate is favored by the strong
ability of 1,2-dihydroxybenzenes to form stable as-
sociates with amides. Such associates are charac-
terized by conservation of intramolecular hydrogen
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 8 2011

SYNTHESIS AND MOLECULAR STRUCTURE
bond OH···O in the aromatic fragment and appearance
1701
Me
O
O
O
of intermolecular hydrogen bond OH···O=C with the
amide carbonyl group [7, 8].
NH2
NH2+
KOH
HN
Cl−
EtO
+
H2N
Initial aryl chloromethyl ketones Va–Vc were
synthesized by chlorination of acetophenones VIIIa–
VIIIc with gaseous chlorine in glacial acetic acid
under irradiation; the crystalline products were isolated
by treatment of the reaction mixture with finely
crushed ice. Physical parameters of compounds Va–Vc
coincided with those reported in the literature.
N
XI
H2N
Me
MeI
O
O
Me
Me
N
HCl
N
Cl−
Me
Ar
Me
Cl2
Vа_Vc
N+
H
hν
N
Me
O
H2N
H2N
VIIIa−VIIIc
IX
XII
The structure of 1-pyrimidinyl-2-thiazolylhydra-
zines VIIa–VIIc was confirmed by the 1H NMR
spectra which characteristically contained a singlet at δ
~3.2 ppm due to protons in the N-methyl group, a
multiplet in the region δ 6.7–7.6 ppm due to aromatic
protons, and NH proton signals as broadened or
degenerate singlets at δ 9.3–9.6 ppm. Apart from these
Aminothiazole hydrochloride X was prepared by
cyclization of equimolar amounts of thiourea and
phenyl chloromethyl ketone (Va) in boiling ethanol.
Ph
H
N+
NH2
Vа
Cl_
S
1
H2N
H2N
signals, compound VIIc displayed in the H NMR
S
spectrum singlets from protons in the solvate dimethyl-
formamide molecule at δ 2.7–3.0 (CH3) and ~8.0 ppm
(CHO); the overall intensity of these signals was
estimated as 7H assuming that the intensity of the 5-H
signal (pyrimidine ring) is equal to 1H.
X
The UV absorption patterns of compounds VIIa,
IX, and X indicated that our assumption implying
localization of proton at one endocyclic nitrogen atom
in 1-pyrimidinyl-2-thiazolylhydrazine VIIa was
erroneous. In fact, the UV spectrum of VIIa is
represented by a curve with two inflections, only one
of which (at about λ 260 nm) coincides with the
shoulder observed in the spectrum of aminothiazole
hydrochloride X (see figure). Apart from absorption by
the aromatic systems, this spectral region contains
absorption of protonated 2-aminopyrimidin-4(3H)-
ones in the imino lactam form [10]. Taking into
account the above stated, as well as the fact that
extended conjugation chain in the molecule of 1-
pyrimidinyl-2-thiazolylhydrazine VIIa can appear only
as a result of interdependent tautomeric rearrange-
ments of its heterocyclic fragments, the structure of
compound VIIa may be represented by canonical
formulas A and D.
In order to determine the site of proton addition in
molecules VIIa–VIIc, estimation of the contribution
of each heterocycle was necessary. For this purpose,
the UV spectrum of VIIa was compared with the
spectra of model compounds, 2-amino-3,6-
dimethylpyrimidin-4(3H)-one hydrochloride (IX) and
2-amino-4-phenyl-1,3-thiazole hydrochloride (X)
assuming that n→π*-electron transitions in molecules
VIIa–VIIc are restricted by the HNex−C2=N1 bond
systems in the pyrimidine and thiazole rings.
Aminopyrimidinone hydrochloride IX was
synthesized according to a scheme of transformations
including cyclocondensation of guanidine as free base
(preliminarily generated by neutralization of guanidine
hydrochloride with potassium hydroxide in ethanol)
with ethyl acetoacetate, methylation of 2-amino-6-
methylpyrimidin-4(3H)-one (XI) at the N3 atom with
methyl iodide in ethanol in the presence of potassium
hydroxide as described in [9], and final treatment of 2-
amino-3,6-dimethylpyrimidin-4(3H)-one (XII) with
hydrogen chloride.
An indisputable proof for the assumed structure of
compound VIIa (A↔D) is the presence in its UV
spectrum of a low-intensity long-wave shoulder at
about λ 310 nm. This shoulder is located at longer
wavelengths relative to the absorption maximum of
aminopyrimidinone hydrochloride IX (λ 283 nm), and
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 8 2011

1702
ERKIN, KRUTIKOV
O
O
Me
Me
N
N
N
S
N
S
+
N+
H
Me
N
N
H
Me
N
H
H
NH
NH
Ph
Ph
B
A
O
O
Me
Me
N
N
H
H
N+
S
N
S
N
N
H
Me
N
N
H
Me
NH+
NH
Ph
Ph
C
D
it corresponds to n→π*-electron transitions in the
conjugation chain intrinsic to protonated imino
tautomers B and C.
solutions in ethanol with a concentration of ~1×10–4 M.
The purity of the isolated compounds was checked by
TLC on Silufol UV-254 plates using the following
solvent systems as eluents: butan-1-ol–acetic acid–
water, 1:1:1 (A); propan-2-ol–25% aqueous ammonia,
3:1 (B); butan-1-ol–acetic acid, 1:1, and 10 drops of
water (C). Spots were developed by UV irradiation.
The elemental compositions were determined on a
Hewlett–Packard B-185 analyzer. Aqueous or
aqueous–ethanolic solutions of compounds IIIa, IIIb,
VI, VIIa–VIIc, IX, and X showed a positive test for
chloride ion upon treatment with an aqueous solution
of silver nitrate.
EXPERIMENTAL
1
The H NMR spectra were recorded on a Bruker
WM-400 spectrometer at 400.13 MHz using DMSO-d6
as solvent and reference. The IR spectra were obtained
on an FSM-1201 spectrometer with Fourier transform
from samples prepared as KBr pellets. The UV spectra
were measured on an SF-26 spectrophotometer from
ε, l mol–1 cm–1
2-Hydrazino-6-methyl- and 2-hydrazino-3,6-dimethyl-
pyrimidin-4(3H)-ones IVa and IVb were synthesized
according to the procedures described in [11, 12],
respectively.
1-(6-Methyl-4-oxo-3,4-dihydropyrimidin-2-yl)thio-
semicarbazide (IIa). Hydrochloride IIIa, 3 g, was
added in portions under stirring to a solution of 1.65 g
of potassium thiocyanate in 15 ml of water. The
mixture was stirred for 30 min at room temperature,
filtered, and neutralized to pH 6 with 25% aqueous
ammonia. The precipitate was filtered off, washed with
a small amount of cold water, and dried at 80°C for
8 h. Yield 2 g (59%), mp 186°C, Rf 0.44 (A). 1H NMR
spectrum, δ, ppm: 2.14 s (3H, Me), 5.57 s (1H, CH),
7.99 br.s (5H, NH2, NH). Found, %: C 35.87; H 4.31;
N 34.72. C6H9N5OS. Calculated, %: C 36.17; H 4.55;
N 35.15.
λ, nm
UV spectra of (1) 2-amino-3,6-dimethylpyrimidin-4(3H)-one
hydrochloride (IX), (2) 2-amino-4-phenyl-1,3-thiazole
hydrochloride (X), and (3) 3,6-dimethyl-2-(4-phenyl-1,3-
thiazol-2-ylhydrazino)-3,4-dihydropyrimidin-4-one hydro-
chloride (VIIa).
1-(3,6-Dimethyl-4-oxo-3,4-dihydropyrimidin-2-
yl)thiosemicarbazide (IIb). Hydrochloride IIIb,
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SYNTHESIS AND MOLECULAR STRUCTURE
1703
3.31 g, was added in portions under stirring to a
solution of 1.79 g of potassium thiocyanate in 20 ml of
water. The mixture was stirred for 3 h, and the
precipitate was filtered off, washed with a small
amount of cold water, and dried at 80°C for 8 h. Yield
anhydrous butan-1-ol was heated for 2 h under reflux
in a flask equipped with a Dean–Stark trap. The
mixture was cooled, and the precipitate was filtered
off, washed with butan-1-ol, recrystallized from
ethanol, and dried under reduced pressure over phos-
phorus(V) oxide. Yield 0.45 g (27%), mp 241°C
1
2.32 g (63%), mp 167°C, Rf 0.65 (A). H NMR
1
spectrum, δ, ppm: 2.22 s (3H, Me), 3.21 s (3H, NMe),
5.75 s (1H, CH), 9.08 br.s (4H, NH2, NH). Found, %:
C 39.46; H 5.03; N 32.68. C7H11N5OS. Calculated, %:
C 39.42; H 5.20; N 32.84.
(decomp.), Rf 0.24 (C). H NMR spectrum, δ, ppm:
2.05 s (3H, Me), 3.22 s (3H, NMe), 5.43 s (1H, CH),
7.07 s (1H, CH), 7.41–7.45 m (5H, Ph), 9.56 br.s (2H,
NH), 10.95 s (1H, N+H). Found, %: C 51.33; H 4.78;
N 19.83. C15H15N5OS·HCl. Calculated, %: C 51.50; H
4.61; N 20.02.
2-Hydrazino-6-methylpyrimidin-4(3H)-one hyd-
rochloride (IIIa). Hydrazinopyrimidine IVa, 3 g, was
dissolved in 30 ml of concentrated hydrochloric acid
under stirring. The resulting solution was evaporated
under reduced pressure, the residue was treated with
30 ml of ethanol heated to 60°C, and the precipitate
was filtered off, washed with ethanol, and dried at 80°C
over a period of 8 h. Yield 3.43 g (91%), mp 217°C, Rf
0.64 (A).
2-[4-(4-Chlorophenyl)-1,3-thiazol-2-ylhydrazino]-
3,6-dimethyl-3,4-dihydropyrimidin-4-one hydro-
chloride (VIIb). A mixture of 0.5 g of thiosemi-
carbazide IIb and 4-chlorophenyl chloromethyl ketone
(Vb) was heated for 15 min at 100–105°C. After
cooling, the melt was mechanically ground and treated
with 10 ml of boiling anhydrous acetonitrile. The
precipitate was filtered off, washed with acetonitrile,
and dried in air. The product was purified by recrystal-
lization from nitromethane–DMF (7:5), followed by
heating in 10 ml of boiling anhydrous diethyl ether to
remove residual high-boiling solvents. After drying in
a high vacuum, we obtained 0.14 g (16%) of hydro-
chloride VIIb with mp 239°C (decomp.), Rf 0.69 (A).
1H NMR spectrum, δ, ppm: 2.03 s (3H, Me), 3.17 s
(3H, NMe), 5.44 s (1H, CH), 7.13 s (1H, CH), 7.43–
7.57 m (5H, Ph), 9.55 br.s (2H, NH), 10.97 s (1H,
N+H). Found, %: C 46.41; H 3.71; N 18.11.
C15H14ClN5OS·HCl. Calculated, %: C 46.88; H 3.93;
N 18.22.
2-Hydrazino-3,6-dimethylpyrimidin-4(3H)-one
hydrochloride (IIIb). Hydrazinopyrimidine IVb, 2 g,
was dissolved in 10 ml of concentrated hydrochloric
acid under stirring. The resulting solution was eva-
porated under reduced pressure, and the residue was
recrystallized from ethanol, washed with ethanol, and
dried at 80°C over a period of 8 h. Yield 2.06 g (83%),
mp 199°C, Rf 0.68 (B).
General procedure for the preparation of aryl
chloromethyl ketones Va–Vc. A stream of chlorine
generated by reaction of potassium permanganate with
concentrated hydrochloric acid was passed through a
solution of 0.06 mol of acetophenone VIIIa–VIIIc in
30 ml of glacial acetic acid under irradiation with a
filament lamp. The amounts of KMnO4 and HCl were
calculated so that to ensure a substrate-to-reagent ratio
of 1:1.1. The resulting suspension was purged with air
to remove excess hydrogen chloride and treated with
finely crushed ice under stirring, and the precipitate
was filtered off, washed with cold water, and dried in
air. After recrystallization and drying under reduced
pressure, compounds Va–Vc had the following melting
points: Va, 58°C (from ethanol; published data [13]:
mp 58–59°C); Vb, 102°C (from ethanol–hexane, 1:1;
published data [14]: mp 101°C); Vc, 178°C (from
ethyl acetate; published data [15]: mp 173°C).
2-[4-(3,4-Dihydroxyphenyl)-1,3-thiazol-2-ylhyd-
razino]-3,6-dimethyl-3,4-dihydropyrimidin-4-one
hydrochloride (VIIc). A mixture of 1 g of thiosemi-
carbazide IIb and 3,4-dihydroxyphenyl chloromethyl
ketone (Vc) in 30 ml of anhydrous butan-1-ol was
heated for 2 h under reflux in a flask equipped with a
Dean–Stark trap. After cooling, the precipitate was
filtered off, washed with ethanol, and dried in air. The
product was dispersed in ethanol, the suspension was
heated to the boiling point, and DMF was added to the
boiling suspension until it turned homogeneous. After
cooling, the precipitate was filtered off, washed with
ethanol, and dried under reduced pressure over
phosphorus(V) oxide. Yield 0.86 g (40%, solvate with
1
3,6-Dimethyl-2-(4-phenyl-1,3-thiazol-2-ylhydra-
zino)-3,4-dihydropyrimidin-4-one hydrochloride
(VIIa). A mixture of 1 g of thiosemicarbazide IIb and
phenyl chloromethyl ketone (Va) in 30 ml of
DMF), mp > 220°C (decomp.), Rf 0.41 (C). H NMR
spectrum, δ, ppm: 2.03 s (3H, Me), 2.75 s (3H, NMe),
2.91 s (3H, NMe), 3.18 s (3H, NMe), 5.46 s (1H, CH),
6.70–6.88 m (4H, CH, Harom), 7.93 s (1H, CHO), 9.28
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 8 2011

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ERKIN, KRUTIKOV
m (4H, NH, OH), 10.76 s (1H, N+H). Found, %:
C 47.08; H 4.88; N 18.02. C15H15N5O3S·HCl·C3H7NO.
Calculated, %: C 47.52; H 5.10; N 18.47.
ACKNOWLEDGMENTS
The authors thank I.V. Klaptyuk (All-Russian
Research Fire-Prevention Institute, Ministry of the
Russian Federation for Civil Defense, Emergencies,
and Elimination of Consequences of Natural Disasters)
for recording the IR spectra.
2-Amino-3,6-dimethylpyrimidin-4(3H)-one hydro-
chloride (IX). Free base XII, 0.4 g, was dissolved in
10 ml of concentrated hydrochloric acid. The solution
was evaporated under reduced pressure at a tem-
perature not exceeding 60°C. The residue (a semi-
crystalline material) was treated with 5 ml of an-
hydrous acetonitrile, and the precipitate was filtered
off, recrystallized from propan-2-ol, and dried under
reduced pressure over phosphorus(V) oxide. Yield
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0.18 g (36%), mp 262°C (decomp.), Rf 0.51 (A). H
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and dried at 70°C over a period of 4 h. Yield 3.6 g
(85%), mp 206°C; published data [16]: mp 176–177°C;
1
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14. Gautier, M.H., Ann. Chim. Phys., 1888, Ser. VI, p. 337.
15. Dzerzhgovskii, S.K., Zh. Russ. Fiz-Khim. Ob-va., 1893,
vol. 25, part 1, p. 154.
16. Sagidova, S.E., Magerramov, A.M., Allakhverdiev, M.A.,
and Vekilova, T.M., Zh. Prikl. Khim., 2004, vol. 77,
no. 5, p. 791.
2-Amino-6-methylpyrimidin-4(3H)-one
(XI).
Guanidine hydrochloride, 4.78 g, was added to a
solution of 2.8 g of potassium hydroxide in 30 ml of
ethanol. The resulting suspension was heated for 5 min
under reflux and cooled to room temperature, the
precipitate was filtered off, and a solution of 6.5 g of
ethyl acetoacetate in 5 ml of ethanol was added to the
filtrate. The mixture was heated for 6 h under reflux
and cooled, and the precipitate was filtered off,
recrystallized from water, and dried at 70°C over a
period of 8 h. Yield 3.37 g (54%), mp > 300°C, Rf 0.59
(A). Found, %: C 47.73; H 5.65; N 33.41. C5H7N3O.
Calculated, %: C 47.99; H 5.64; N 33.58.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 8 2011