Synthesis of arylamino-substituted pyrazolo[3,4-d][1,2,4]triazolo[4,3-a] pyrimidinones, pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones, and their thermal isomerization

Article abstract of DOI:10.1134/S1070428010020235

The reaction of 1-(4-oxo-1-R-5H-pyrazolo[3,4-d]pyrimidin-6-yl)-4- arylthiosemicarbazides with methyl iodide gave rise to 1,2,4-triazolo- pyrazolopyrimidinones of linear structure, and with dicyclohexylcarbodiimide the products had angular and linear structure. The heating of compounds obtained higher than their melting point resulted in their isomerization into 7-aryl-amino-1-R-1,8-dihydro-4H-pyrazolo[3,4-d]-[1,2,4]triazolo[1,5-a] pyrimidin-4-ones.

Full text of DOI:10.1134/S1070428010020235

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 2, pp. 286−291. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © R.I. Vas’kevich, A.V. Bentya, V.I. Staninets, 2009, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 2, pp. 290−
294.
Synthesis ofArylamino-Substituted
Pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]pyrimidinones,
Pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones,
and Their Thermal Isomerization
R. I. Vas’kevich, A. V. Bentya, and V. I. Staninets
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, 02660 Ukraine
e-mail: vaskevich@ioch.kiev.ua
Received May 27, 2009
Abstract—The reaction of 1-(4-oxo-1-R-5H-pyrazolo[3,4-d]pyrimidin-6-yl)-4-arylthiosemicarbazides with methyl
iodide gave rise to 1,2,4-triazolo-pyrazolopyrimidinones of linear structure, and with dicyclohexylcarbodiimide the
products had angular and linear structure. The heating of compounds obtained higher than their melting point
resulted in their isomerization into 7-aryl-amino-1-R-1,8-dihydro-4H-pyrazolo[3,4-d]-[1,2,4]triazolo[1,5-a]pyrimidin-
4-ones.
DOI: 10.1134/S1070428010020235
vary the substituent at N1 atom and also to study the
effect of the π-excessive pyrazole ring on the regio-
chemistry of the triazole ring formation.
It was formerly reported that the cyclization of 1-(4,6-
dimethylpyrimidin-2-yl)-4-arylthiosemicarbazides under
the action of methyl iodide and sodium acetate in ethanol
resulted in the products of Dimroth rearrangement, 2-aryl-
amino-5,7-dimethyl-1,2,4-triasolo[1,5-a]pyrimidines [1].
In the presence of dicyclohexylcarbodiimide the cycliza-
tion was accompanied by the formation of unrearranged
compounds, 3-arylamino-5,7-dimethyl-1,2,4-triazolo[1,5-a]-
pyrimidines which further under alkaline conditions suffer-
ed the Dimroth rearrangement [2]. At the same time 1-(6-
methyl-4-oxo-3,4-dihydropyrimidin-2-yl)-4-arylthio-
semicarbazides in reactions with methyl iodide and
sodium acetate provided 3-arylamino-7-methyl-5-oxo-1-
hydro-1,2,4-triazolo[4,3-a]pyrimidines which did not suffer
the catalytic Dimroth rearrangement [1].
In the reaction of thiosemicarbazides IIIa–IIIc, IVa–
IVc with methyl iodide and sodium acetate in ethanol
the closure of the triazole ring occurred only at the N5
atom of the pyrazolopyrimidine framework with the
formation of pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]-
pyrimidinones of linear structure Va–Vc, VIa–VIc. The
similar cyclization regiochemistry we previously
established by the XRD method for thiosemicarbazides
containing in the position 1 a pyrimidinone ring [1, 3].
Compounds IIIa–IIIc reacted with dicyclohexyl-
carbodiimide in dioxane nonselectively. We isolated in 37–
60% yield and identified pyrazolo[4,3-e][1,2,4]triazolo-
[4,3-a]pyrimidinones of angular structure VIIa–VIIc.
Besides in 15–40% yields compounds of linear structure
Va–Vc formed and were present in the filtrate. It should
be noted that the yield of the compound VIIb of the
angular structure was considerably lower, and the yield
of compound Vb of the linear structure greater in the
case of Ar = 4-CH3OC6H4. It was also established that
at the cyclization of compound IVa effected by
dicyclohexylcarbodiimide the yield of the product of the
Aiming at a deeper understanding of the cyclization
regiochemistry of 1-hetaryl-4-arylthiosemicarbazides
under the action of methyl iodide and dicyclohexylcarbo-
diimide we tested 1-(4-oxo-1-R-5H-pyrazolo[3,4-d]-
pyrimidin-6-yl)-4-arylthiosemicarbazides IIIa–IIIc, IVa–
IVc obtained from the corresponding 6-hydrazino-sub-
stituted pyrazolopyrimidines I and II (see the scheme).
In compounds IIIa–IIIc, IVa–IVc the pyrimidine ring is
fused with a pyrazole cycle providing a possibility to
286

SYNTHESIS OF ARYLAMINO-SUBSTITUTED PYRAZOLO[3,4-d][1,2,4]TRIAZOLO[4,3-a]PYRIMIDINONES
287
Ar
O
O
HN
N
N
N
D
Ar
N
N
N
N
H
N
H
N
N
N
N
N
H
Va_Vc, VIa_VIc
CH3I, AcONa
O
R
R
IXa, Xa
O
N
Δ
ArNCS
NH
NH
N
N
H
N
H
N
NH2
N
N
N
N
N
Ar
H
H
IIIa_IIIc, IVa_IVc
R
R
I, II
S
O
N C
N
NH
Va_Vc, VIa + N
Dioxane
N
N
N
R
N
NH
Ar
VIIa_VIIc, VIIIa
R = H (I, III, V, VII, IX), Ph (II, IV, VI, VIII, X);Ar = C6H5 (a), 4-CH3OC6H4 (b), 4-C2H5O2CC6H4 (c).
structure the difference was observed in the chemical
sifts of protons at the nitrogen atoms. For instance, the
singlet of the proton of the NHAr group in the compounds
of linear structure was observed in the region 9.29–9.90
ppm, and in the compounds of the angular structure, at
8.31–9.05 ppm. The singlet of the NH proton of the
pyrimidine fragment in the spectra of compounds of the
angular structur appeared at 12.02–12.50 ppm, and in
the spectra of compounds of the linear structure the singlet
of the triazole proton of the NH group was located in the
region 12.84–13.63 ppm.
angular structure VIIIa was twice less than in the case
of cyclization of compound IIIa.
We investigated the ability to rearrange of compounds
V–VII at heating in alcohol solutions of sodium acetate
and alkaline DMSO solutions. It turned out that under
catalytic conditions the Dimroth rearrangement [4–6]
products did not form, and the isolated only initial
compounds. Therefore we attempted to perform the
Dimroth rearrangement at heating [6, 7]. For instance,
at heating compounds Va and VIa over their melting points
(320 and 360°C respectively) we obtained rearrangement
products IXa and Xa. Yet compound VIIa of the angular
structure underwent the rearrangement into compound
IXa only at the temperature over 400°C.
In the IR spectra of the cyclization products the
stretching vibrations of the carbonyl group in the
compounds of the linear structure Va, IXa were found
at 1720, 1730 cm–1, and for the angular compound VIIa,
in the region 1690 cm–1.
The composition and structure of synthesized
compounds V–X were confirmed by elemental analysis,
IR and 1H NMR spectra.
In the 1H NMR spectra of compounds with the angular
VIIa–VIIc, VIIIa and linear Va–Vc, VIa–VIc, IXa, Xa
Thus we established that the cyclization of
thiosemicarbazides IIIa–IIIc, IVa–IVc effected by
methyl iodide and sodium acetate in ethanol proceeded
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VAS’KEVICH et al.
288
regioselectively at the N5 atom of the pyrazolopyrimidine
framework, and under the action of dicyclohexylcarbo-
diimide it occurred at the atoms N7 and N5 of the
pyrazolopyrimidine system. The heating of pyrazolo-
triazolopyrimidines of the linear (V, VI) and angular (VII)
structure higher than their melting points resulted in their
isomerization into 7-arylamino-1-R-1,8-dihydro-4H-
pyrazolo[3,4-d][1,2,4]triazolo[1,5-a]pyrimidin-4-ones.
pyrimidin-6-yl)-4-(4-ethoxycarbonyl-phenyl)-
thiosemicarbazide (IIIc). Yield 0.88 g (47%), mp
>360°C. IR spectrum, ν, cm–1: 3200, 3120, 2980 (NH),
1710 (C=O), 1620, 1550, 1370, 1280, 1180, 1110, 1020,
960, 930. 1H NMR spectrum, δ, ppm: 1.32 t (3H, CH3,
J 6.9 Hz), 4.30 q (2H, CH2, J 7.2 Hz), 7.78 d (2Harom
,
J 8.4 Hz), 7.82–7.93 m (3Harom), 8.70 br.s (1H, NH),
9.91 br.s (1H, NH), 10.13 br.s (1H, NH), 10.96 br.s (1H,
NH), 13.24 br.s (1H, NH). Found, %: C 47.98; H 3.97;
N 26.12; S 8.44. C15H15N7O3S. Calculated, %: C 48.25;
H 4.05; N 26.26; S 8.59.
EXPERIMENTAL
IR spectra were recorded on a spectrophotometer
UR-20 from pellets with KBr. H NMR spectra were
registered on a spectrometer VXR-300 (300 MHz) in
DMSO-d6 with internal reference TMS.
1-(4-Oxo-1-phenyl-4,5-dihydro-1H-pyrazolo-
[3,4-d]pyrimidin-6-yl)-4-arylthiosemicarbazides
IVa–IVc. A mixture of 1.21 g (5 mmol) of reagent II
and 7 mmol of an appropriate isothiocyanate in 50 ml of
ethanol was boiled at stirring for 1 h, then the solution
was cooled, the separated precipitate was filtered off
and washed with ethanol and ether.
1
1-(4-Oxo-4,5-dihydro-1H-pyrazolo[3,4-d]-
pyrimidin-6-yl)-4-arylthiosemicarbazides IIIa–IIIc.
A mixture of 0.83 g (5 mmol) of reagent I and 7 mmol of
an appropriate isothiocyanate in 50 ml of ethanol was
boiled at stirring for 4 h, then the solution was cooled, the
separated precipitate was filtered off and washed with
ethanol. To purify the precipitate obtained it was boiled
for 10 min with 0.61 ml (5 mmol) of acetylenedicarboxylic
ester in 40 ml of dioxane. The reaction mixture was
cooled, the precipitate was filtered off, washed with
dioxane and with ether.
1-(4-Oxo-1-phenyl-4,5-dihydro-1H-pyrazolo-
[3,4-d]pyrimidin-6-yl)-4-phenylthiosemicarbazide
(IVa). Yield 1.26 g (67%), mp 187–189°C (decomp.). IR
spectrum, ν, cm–1: 3270 (NH), 1670 (C=O), 1630, 1600,
1540, 1510, 1450, 1430, 1410, 1370, 1300, 1260, 1120,
960. 1H NMR spectrum, δ, ppm: 7.15 t (1Harom, J 7.2 Hz),
7.29–7.35 m (3Harom), 7.46–7.51 m (4Harom), 8.12 s
(1Harom), 8.20 d (2Harom, J 8.1 Hz), 9.07 br.s (1H, NH),
9.67 s (1H, NH), 9.98 br.s (1H, NH), 11.33 s (1H, NH).
Found, %: C 57.07; H 3.95; N 25.71; S 8.41. C18H15N7OS.
Calculated, %: C 57.28; H 4.01; N 25.98; S 8.50.
1-(4-Oxo-4,5-dihydro-1H-pyrazolo[3,4-d]-
pyrimidin-6-yl)-4-phenyl-thiosemicarbazide (IIIa).
Yield 0.84 γ (56%), mp >360°C. IR spectrum, ν, cm–1:
3200, 3050 (NH), 1700 (C=O), 1610, 1460, 1360, 960.
1H NMR spectrum, δ, ppm: 7.15 t (1Harom, J 7.5 Hz),
7.33 t (2Harom, J 7.8 Hz), 7.51 d (2Harom, J 7.8 Hz),
7.85 s (1Harom), 8.66 br.s (1H, NH), 9.68 s (1H, NH),
9.92 s (1H, NH), 10.90 s (1H, NH), 13.24 s (1H, NH).
Found, %: C 47.64; H 3.61; N 32.33; S 10.47.
C12H11N7OS. Calculated, %: C 47.83; H 3.68; N 32.54;
S 10.64.
4-(4-Methoxyphenyl)-1-(4-oxo-1-phenyl-4,5-
dihydro-1H-pyrazolo[3,4-d]pyrimidin-6-yl)-
thiosemicarbazide (IVb). Yield 1.63 g (80%), mp 155–
157°C (decomp.). IR spectrum, ν, cm–1: 3230 (NH), 1690
1
(C=O), 1620, 1520, 1300, 1250, 1030, 970. H NMR
spectrum, δ, ppm: 3.74 s (3H, OCH3), 6.88 d (2Harom
,
J 9.0 Hz), 7.32–7.36 m (3Harom), 7.50 t (2Harom, J 7.8 Hz),
8.13 s (1Harom), 8.22 d (2Harom, J 8.7 Hz), 9.09 br.s (1H,
NH), 9.59 br.s (1H, NH), 9.85 br.s (1H, NH), 11.31 s
(1H, NH). Found, %: C 55.92; H 4.07; N 23.95; S 7.65.
C19H17N7O2S. Calculated, %: C 56.01; H 4.21; N 24.06;
S 7.87.
1-(4-Oxo-4,5-dihydro-1H-pyrazolo[3,4-d]-
pyrimidin-6-yl)-4-(4-methoxyphenyl)thiosemi-
carbazide (IIIb). Yield 1.01 g (61%), mp >360°C. IR
spectrum, ν, cm–1: 3200, 3020 (NH), 1700 (C=O), 1620,
1530, 1360, 1300, 1250, 1040, 960. 1H NMR spectrum,
δ, ppm: 3.75 s (3H, OCH3), 6.89 d (2Harom, J 8.7 Hz),
7.34 d (2Harom, J 8.7 Hz), 7.85 s (1Harom), 8.63 br.s (1H,
NH), 9.58 s (1H, NH), 9.81 s (1H, NH), 10.86 s (1H,
NH), 13.25 s (1H, NH). Found, %: C 46.93; H 3.83;
N 29.39; S 9.51. C13H13N7O2S. Calculated, %: C 47.12;
H 3.95; N 29.59; S 9.68.
1-(4-Oxo-1-phenyl-4,5-dihydro-1H-pyrazolo-
[3,4-d]pyrimidin-6-yl)-4-(4-ethoxycarbonyl-
phenyl)thiosemicarbazide (IVc). Yield 1.62 g (72%),
mp 166–169°C (decomp.). IR spectrum, ν, cm–1: 3280,
3190 (NH), 1700 (C=O), 1650, 1600, 1550, 1510, 1340,
1290, 1230, 1180, 1120, 1020, 960. 1H NMR spectrum, δ,
ppm: 1.31 t (3H, CH3, J 7.2 Hz), 4.29 q (2H, CH2,
1-(4-Oxo-4,5-dihydro-1H-pyrazolo[3,4-d]-
J 7.2 Hz), 7.33 t (1Harom, J 7.2 Hz), 7.48 t (2Harom,
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SYNTHESIS OF ARYLAMINO-SUBSTITUTED PYRAZOLO[3,4-d][1,2,4]TRIAZOLO[4,3-a]PYRIMIDINONES
289
J 7.2 Hz), 7.77 d (2Harom, J 8.4 Hz), 7.90 d (2Harom
,
pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]pyrimidin-5-one
(VIa). Yield 0.67 g (98%), mp 341–343°C (decomp.)
(ethanol–DMSO). IR spectrum, ν, cm–1: 3320, 3100, 3060
(NH), 1730 (C=O), 1690, 1620, 1590, 1560, 1520, 1470,
1420, 1300, 1250, 1190, 1080, 1060, 990, 920. 1H NMR
spectrum, δ, ppm: 7.05 t (1Harom, J 7.5 Hz), 7.34–7.41 m
(3Harom), 7.54–7.64 m (4Harom), 8.10 d (2Harom, J 7.5 Hz),
8.32 s (1Harom), 9.51 s (1H, NH), 13.43 s (1H, NH).
Found, %: C 62.79; H 3.77; N 28.43. C18H13N7O.
Calculated, %: C 62.97; H 3.82; N 28.56.
J 8.7 Hz), 8.13 s (1Harom), 8.17 d (2Harom, J 7.8 Hz),
9.19 br.s (1H, NH), 9.91 br.s (1H, NH), 10.20 br.s (1H,
NH), 11.47 br.s (1H, NH). Found, %: C 56.05; H 4.16;
N 21.77; S 7.06. C21H19N7O3S. Calculated, %: C 56.11;
H 4.26; N 21.81; S 7.13.
3-Arylamino-1,8-dihydro-5H-pyrazolo[3,4-d]-
[1,2,4]triazolo[4,3-a]-pyrimidin-5-ones Va–Vc, VIa–
VIc. A mixture of 2 mmol of an appropriate thiosemi-
carbazide IIIa–IIIc, IVa–IVc, 0.25 g (3 mmol) of sodium
acetate, and 0.19 ml (3 mmol) of methyl iodide in 50 ml
of ethanol was boiled at stirring for 1 h, then the solution
was cooled to room temperature, the separated precipitate
was filtered off and washed on the filter with ethanol
and ether.
3-(4-Methoxyphenylamino)-8-phenyl-1,8-di-
hydro-5H-pyrazolo[3,4-d]-[1,2,4]triazolo[4,3-a]-
pyrimidin-5-one (VIb). Yield 0.68 g (91%), mp 309–
311°C (ethanol–DMSO). IR spectrum, ν, cm–1: 3100,
2800 (NH), 1720 (C=O), 1680, 1620, 1580, 1550, 1520,
1
1250, 1180, 1030, 980. H NMR spectrum, δ, ppm: 3.73
3-Phenylamino-1,8-dihydro-5H-pyrazolo[3,4-d]-
[1,2,4]triazolo[4,3-a]-pyrimidin-5-one (Va). Yield
0.46 g (86%), mp 308–310°C (ethanol–DMSO). IR
spectrum, ν, cm–1: 3310, 3070 (NH), 1720 (C=O), 1660,
1600, 1570, 980, 920, 870, 820, 760. 1H NMR spectrum,
δ, ppm: 7.03 t (1Harom, J 7.5 Hz), 7.38 t (2Harom, J 7.8 Hz),
7.60 d (2Harom, J 7.8 Hz), 8.05 s (1Harom), 9.57 s (1H,
NH), 13.00 s, 13.11 s (2H, 2NH). Found, %: C 53.74;
H 3.22; N 36.47. C12H9N7O. Calculated, %: C 53.93;
H 3.39; N 36.69.
s (3H, OCH3), 6.94 d (2Harom, J 9.0 Hz), 7.35 t (1Harom
,
J 7.8 Hz), 7.52–7.58 m (4Harom), 8.09 d (2Harom, J 8.7 Hz),
8.30 s (1Harom), 9.29 s (1H, NH), 13.33 s (1H, NH).
Found, %: C 60.95; H 3.98; N 26.17. C19H15N7O2.
Calculated, %: C 61.12; H 4.05; N 26.26.
8-Phenyl-3-(4-ethoxycarbonylphenylamino)-1,8-
dihydro-5H-pyrazolo-[3,4 d][1,2,4]triazolo-[4,3-
a]pyrimidin-5-one (VIc). Yield 0.71 g (85%), mp 316–
318°C (ethanol–DMSO). IR spectrum, ν, cm–1: 3180,
2980 (NH), 1740, 1710 (C=O), 1680, 1620, 1550, 1510,
1430, 1290, 1180, 1110, 980, 910. 1H NMR spectrum, δ,
ppm: 1.32 t (3H, CH3, J 7.2 Hz), 4.28 q (2H, CH2,
3-(4-Methoxyphenylamino)-1,8-dihydro-5H-
pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]pyrimidin-5-one
(Vb). Yield 0.52 g (87%), mp 310–312°C (ethanol–
DMSO). IR spectrum, ν, cm–1: 3310, 3070, 2920, 2840
(NH), 1740 (C=O), 1670, 1620, 1570, 1530, 1240, 1180,
J 7.2 Hz), 7.37 t (1Harom, J 7.8 Hz), 7.57 t (2Harom
J 7.8 Hz), 7.72 d (2Harom, J 8.7 Hz), 7.96 d (2Harom
,
,
J 9.0 Hz), 8.10 d (2Harom, J 7.8 Hz), 8.35 s (1Harom), 9.83 s
(1H, NH), 13.63 s (1H, NH). Found, %: C 60.66; H 4.02;
N 23.47. C21H17N7O3. Calculated, %: C 60.72; H 4.13;
N 23.60.
1
1120, 1030, 970. H NMR spectrum, δ, ppm: 3.74 s (3H,
OCH3), 6.94 d (2Harom, J 8.4 Hz), 7.52 d (2Harom
,
J 8.7 Hz), 8.01 s (1Harom), 9.33 s (1H, NH), 12.84 s (1H,
NH), 13.05 s (1H, NH). Found, %: C 52.45; H 3.67;
N 32.83. C13H11N7O2. Calculated, %: C 52.52; H 3.73;
N 32.98.
8-Arylamino-1H-pyrazolo[4,3-e][1,2,4]triazolo-
[4,3-a]pyrimidin-4(5H)-ones VIIa–VIIc. To a solution
of 0.52 g (2.5 mmol) of dicyclohexylcarbodiimide in 20 ml
of dioxane was added 2 mmol of an appropriate
thiosemicarbazide IIIa–IIIc, and the mixture was boiled
for 40 min on an oil bath (115–120°C). The reaction
mixture was cooled to 30–40°C, the separated precipitate
was filtered off, washed on the filter with dioxane and
ether.
3-(4-Ethoxycarbonylphenylamino)-1,8-dihydro-
5H-pyrazolo[3,4-d][1,2,4]-triazolo[4,3-a]-pyrimidin-
5-one (Vc). Yield 0.52 g (77%), mp 322–324°C (ethanol–
DMSO). IR spectrum, ν, cm–1: 3180 (NH), 1730 (C=O),
1670, 1620, 1560, 1430, 1370, 1320, 1290, 1180, 1100,
1
1050, 1020, 960, 920. H NMR spectrum, δ, ppm: 1.33 t
(3H, CH3, J 6.9 Hz), 4.29 q (2H, CH2, J 7.2 Hz), 7.71 d
(2Harom, J 9.3 Hz), 7.96 d (2Harom, J 8.1 Hz), 8.06 s
(1Harom), 9.90 s (1H, NH), 13.17 m (2H, 2NH). Found,
%: C 52.98; H 3.71; N 28.66. C15H13N7O3. Calculated,
%: C 53.10; H 3.86; N 28.90.
8-Phenylamino-1H-pyrazolo[4,3-e][1,2,4]-
triazolo[4,3-a]pyrimidin-4(5H)-one (VIIa). Yield
0.32 g (60%), mp >360°C (ethanol–DMSO). IR spectrum,
ν, cm–1: 3370, 3100 (NH), 1690 (C=O), 1630, 1580, 1500,
1440, 1400, 1370, 1250, 1220. 1H NMR spectrum, δ, ppm:
8-Phenyl-3-phenylamino-1,8-dihydro-5H-
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VAS’KEVICH et al.
290
Compound Va (0.27 g, 1 mmol) was heated for 5 min on
a sand bath (320°C). The obtained crystalline product
was cooled, transferred to a filter and washed with ethanol
and ether.
6.95 t (1Harom, J 6.6 Hz), 7.33 t (2Harom, J 6.9 Hz), 7.55 d
(2Harom, J 6.9 Hz), 8.39 s (1Harom), 8.69 s (1H, NH),
12.16 br.s (1H, NH), 13.98 s (1H, NH). Found, %:
C 53.67; H 3.23; N 36.54. C12H9N7O. Calculated, %:
C 53.93; H 3.39; N 36.69.
b. Compound VIIa (0.27 g, 1 mmol) was heated in
a test tube in the flame of a burner till the formation of
a porous mass that was treated with water, and the
precipitate was filtered.
8-(4-Methoxyphenylamino)-1H-pyrazolo[4,3-e]-
[1,2,4]triazolo[4,3-a]pyrimidin-4(5H)-one (VIIb).
Yield 0.22 g (37%), mp >360°C (ethanol–DMSO). IR
spectrum, ν, cm–1: 3370, 3100 (NH), 1700 (C=O), 1640,
1590, 1520, 1440, 1410, 1370, 1250, 1210, 1120, 1040,
Yield 0.26 g (96%) (a), 0.22 g (81%) (b), mp > 360°C
(ethanol–DMSO). IR spectrum, ν, cm–1: 3160, 2970
(NH), 1730 (C=O), 1620, 1590, 1460, 1320, 1250, 1210,
1
820, 760. H NMR spectrum, δ, ppm: 3.73 s (3H, OCH3),
6.91 d (2Harom, J 9.3 Hz), 7.53 d (2Harom, J 9.0 Hz), 8.13 s
(1Harom), 8.68 s (1H, NH), 12.02 br.s (1H, NH), 13.97 s
(1H, NH). Found, %: C 52.39; H 3.63; N 32.83.
C13H11N7O2. Calculated, %: C 52.52; H 3.73; N 32.98.
1
1190, 1060, 1030, 980, 930, 830, 750. H NMR spectrum,
δ, ppm: 6.90 t (1Harom, J 7.5 Hz), 7.31 t (2Harom, J 7.8 Hz),
7.69 d (2Harom, J 7.5 Hz), 8.70 s (1Harom), 9.55 s (1H,
NH), 13.08 s (1H, NH), 13.70 s (1H, NH). Found, %:
C 53.74; H 3.27; N 36.58. C12H9N7O. Calculated, %:
C 53.93; H 3.39; N 36.69.
8-(4-Ethoxycarbonylphenylamino)-1H-pyr-
azolo[4,3-e][1,2,4]triazolo-[4,3 a]pyrimidin-4(5H)-
one (VIIc). Yield 0.39 g (57%), mp >360°C (ethanol–
DMSO). IR spectrum, ν, cm–1: 3370, 3100, 3000 (NH),
1750, 1730 (C=O), 1660, 1640, 1600, 1530, 1460, 1440,
1-Phenyl-7-phenylamino-1,8-dihydro-4H-
pyrazolo[3,4-d][1,2,4]triazolo[1,5-a]pyrimidin-4-one
(Xa). Compound VIa (0.34 g, 1 mmol) was heated for
5 min on a sand bath (360°C). The obtained crystalline
product was cooled, transferred to a filter and washed
with ethanol and ether. Yield 0.29 g (85%), mp > 360°C
(ethanol–DMSO). IR spectrum, ν, cm–1: 3380 (NH), 1730
1
1420, 1380, 1290, 1260, 1230, 1190, 1110. H NMR
spectrum, δ, ppm: 1.33 t (3H, CH3, J 6.9 Hz), 4.29 q (2H,
CH2, J 7.2 Hz), 7.52 d (2Harom, J 8.7 Hz), 7.90 d (2Harom
,
J 9.0 Hz), 8.68 s (1Harom), 9.03 s (1H, NH), 12.21 br.s
(1H, NH), 13.97 br.s (1H, NH). Haθ-dενO, %: C 52.98;
H 3.57; N 28.78. C15H13N7O3. Calculated, %: C 53.10;
H 3.86; N 28.90.
(C=O), 1600, 1540, 1510, 1420, 1250, 1170, 1060, 930,
1
860, 760. H NMR spectrum, δ, ppm: 7.03 t (1Harom
J 7.5 Hz), 7.35–7.40 m (3Harom), 7.57 t (2Harom
J 7.8 Hz), 7.67 d (2Harom, J 7.5 Hz), 8.13 d (2Harom
,
,
,
1-Phenyl-8-phenylamino-1H-pyrazolo[4,3-e]-
[1,2,4]triazolo[4,3-a]pyrimidin-4(5H)-one (VIIIa).
To a solution of (2.5 mmol) of dicyclohexylcarbodiimide
in 20 ml of dioxane was added 0.75 g (2 mmol) of
thiosemicarbazide IVa. The mixture was boiled for 40 min
on an oil bath (115–120°C). The reaction mixture was
the cooled, the separated precipitate was filtered off and
treated with a solution of 0.17 g (3 mmol) of KOH in
30 ml of water, the insoluble product was separated, and
the filtrate (compound VIIIa) was acidified with acetic
acid, the separated precipitate was filtered off and washed
with water on the filter. Yield 0.18 g (26%), mp 339–
341°C (decomp.) (ethanol–DMSO). IR spectrum, ν, cm-
J 7.5 Hz), 8.33 s (1Harom), 9.88 s (1H, NH), 13.43 br.s
(1H, NH). Found, %: C 62.84; H 3.76; N 28.43.
C18H13N7O. Calculated, %: C 62.97; H 3.82; N 28.56.
REFERENCES
1. Vas’kevich, R.I., Savitskii, P.V., Zborovskii, Yu.L., Staninets,
V.I., Rusanov, E.B., and Chernega, A.N., Zh. Org. Khim.,
2006, vol. 42, p. 1417.
2. Bishop, B.C., Marley, H., Preston, P.N., and Wright, S.H.B.
J. Chem. Soc., Perkin, Trans. 1, 1999, p. 1527.
3. Vas’kevich, R.I., Savitskii, P.V., Zborovskii, Yu.L., Staninets,
V.I., Turov,A.V., and Chernega,A.N., Zh. Org. Khim., 2006,
vol. 42, p. 1411.
4. Khadem, H.S.El. and Kawai, J., Heterocycles, 1989, vol. 28,
p. 239.
5. Allen, C.F.H., Beilfuss, H.R., Burness, D.M., Reynolds, G.A.,
Tinker, J.F., and VanAllan, J.A., J. Org. Chem., 1959, vol. 24,
p. 787.
1: 3060 (NH), 1730 (C=O), 1610, 1520, 1460, 1410, 1350,
1
1270, 1180. H NMR spectrum, δ, ppm: 6.44 d (2Harom
J 7.8 Hz), 6.75 t (1Harom, J 7.8 Hz), 7.02 t (2Harom
,
,
J 7.8 Hz), 7.23–7.34 m (3Harom), 7.40 s (1Harom), 7.46 d
(2Harom, J 7.2 Hz), 8.31 s (1H, NH), 12.50 s (1H, NH).
Found, %: C 62.83; H 3.73; N 28.45. C18H13N7O.
Calculated, %: C 62.97; H 3.82; N 28.56.
6. Kreutzberger,A., Chem. Ber., 1966, vol. 99, p. 2237.
7. Reimlinger, H., Jacquier, R., and Daunis, J., Chem. Ber., 1971,
vol. 104, p. 2702.
7-Phenylamino-1,8-dihydro-4H-pyrazolo[3,4-d]-
[1,2,4]triazolo[1,5-a]-pyrimidin-4-one (IXa). a.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 2 2010