CYCLIZATIONS OF MONOCYCLIC 5-NITROPYRIDIN-2(1H)-ONES
1209
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alcohol. Yield 0.6 g (86%), mp 181–183°C. H NMR
spectrum (CF3COOH), δ, ppm: 4.23 s (2H, 3-CH2),
6.85 d (1H, 4-N, J = 2.5 Hz), 8.12 d (1H, 5-H, J =
2.5 Hz). Found, %: C 42.74; H 5.68; N 39.80.
C5H8N4O. Calculated, %: C 42.85; H 5.75; N 39.98.
manganese(IV) oxide was filtered off and washed with
several portions of hot water. The filtrate was com-
bined with the washings, evaporated to 1/3 of the
initial volume, cooled, and acidified with concentrated
hydrochloric acid, and the precipitate was filtered off
and dried. Yield 0.5 g (69%), mp 212–214°C (from
ethanol); published data [4]: mp 216–217°C. H NMR
spectrum (CF3COOH), δ, ppm: 7.33 s (1H, 4-H),
8.25 s (1H, 5-H).
(1H-Pyrazol-3-yl)acetic acid hydrochloride (IV).
A solution of 1.0 g (7.14 mmol) of hydrazide III in
20 ml of concentrated hydrochloric acid was heated for
2–3 h at 100°C. After cooling, the precipitate of hydra-
zine hydrochloride was filtered off, the filtrate was
evaporated to dryness, and the residue was purified by
recrystallization from propan-2-ol with addition of
activated charcoal. Yield 0.9 g (78%), mp 138–140°C;
published data [5]: mp 138–140°C. IR spectrum:
ν(C=O) 1725 cm–1. 1H NMR spectrum (CF3COOH), δ,
ppm: 4.16 s (2H, 3-CH2), 6.83 d (1H, 4-H, J = 2.5 Hz),
8.13 d (1H, 5-H, J = 2.5 Hz).
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[(1,4,5-2H3)-1H-Pyrazol-3-yl](2,N,N′,N′-2H4)-
acetohydrazide (X). A mixture of 1.0 g (7.0 mmol) of
compound (I) and 7.8 ml (140 mmol) of deuterated
hydrazine hydrate was heated for 3–5 h at 100–110°C.
When the reaction was complete, the mixture was
evaporated to dryness in a stream of argon. The residue
was ground in ethanol-d6, and the precipitate was
filtered off and recrystallized from ethanol-d6. Yield
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0.8 g (80%), mp 130–132°C. H NMR spectrum
N′-(4-Chlorobenzylidene)(1H-pyrazol-3-yl)-
acetohydrazide (VII). A solution of 0.5 g (3.56 mmol)
of 4-chlorobenzaldehyde (V) in 10 ml of ethanol was
added to a solution of 0.5 g (3.57 mmol) of hydrazide
III in 15 ml of ethanol. The mixture was heated for
10–15 min under reflux and evaporated to dryness.
Yield 0.7 g (75%), colorless crystals, mp 184–185°C
(from water). IR spectrum, ν, cm–1: 1620 (C=N); 1670
(C=O). 1H NMR spectrum (CF3COOH), δ, ppm: 4.18 s
(1H, CH=N), 4.38 s (2H, 3-CH2), 6.80 d (1H, 4-H, J =
2.2 Hz), 7.28 d (2H, 3′-H, 5′-H, J = 7.0 Hz), 7.56 d
(2H, 2′-H, 6′-H, J = 7.0 Hz), 8.06 d (1H, 5-H, J =
2.2 Hz). Found, %: C 54.62; H 4.17; N 21.19.
C12H11ClN4O. Calculated, %: C 54.81; H 4.22; N.33.
(DMSO-d6), δ, ppm: 3.36 s (1H, CHD), 3.44 s (1D,
CHD), 7.07 s (1D, 4-D), 7.60 s (1D, 5-D). Found, %:
C 40.61; H+D 10.20; N 37.89. C5HD7N4O. Calculat-
ed, %: C 40.80; H+D 10.27; N 38.06.
1,3-Dimethyl-5-nitropyridin-2(1H)-one (XII).
A solution of 1.6 ml (38.6 mmol) of concentrated nitric
acid (d = 1.5 g/cm3) in 1.6 ml of concentrated sulfuric
acid was added under stirring to a solution of 4.0 g
(32.5 mmol) of 1,3-dimethylpyridin-2(1H)-one [12] in
16 ml of concentrated sulfuric acid, cooled to 0–5°C.
After 1 h, the mixture was allowed to warm up to 10–
15°C, stirred for 2–3 h at that temperature, poured onto
ice, and neutralized with ammonium hydrogen carbo-
nate. The light yellow precipitate was filtered off and
dried. Yield 4.7 g (87%), mp 142–143°C (from
N′-(4-Nitrobenzylidene)(1H-pyrazol-3-yl)aceto-
hydrazide (VIII). A solution of 0.5 g (3.31 mmol) of
4-nitrobenzaldehyde (VI) in 10 ml of ethanol was
added to a solution of 0.5 g (3.57 mmol) of hydrazide
III in 15.0 ml of ethanol. The mixture was heated for
10–15 min under reflux and cooled, and the precipitate
was filtered off and dried. Yield 0.9 g (99%), light
yellow crystals, mp 242–244°C (from aqueous alcohol,
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propan-2-ol). H NMR spectrum (DMSO-d6), δ, ppm:
2.05 s (3H, 3-CH3), 3.55 s (3H, 1-CH3), 8.05 d (1H,
4-H, J = 3.0 Hz), 9.06 d (1H, 6-H, J = 3.0 Hz). Found,
%: C 49.83; H 4.75; N 16.51. C7H8N2O3. Calculated,
%: C 50.00; H 4.80; N 16.66.
2-(1H-Pyrazol-3-yl)propionohydrazide (XV).
A solution of 1.7 g (10 mmol) of compound XII in
10 ml (200 mmol) of hydrazine hydrate was heated for
3–5 h at 110–120°C. During the process, the originally
yellow solution turned dark red, and evolution of am-
monia and methylamine was observed. The gaseous
products were identified as described above in the
synthesis of compound III according to method c.
When the reaction was complete, excess hydrazine
hydrate was distilled off to dryness in a stream of
argon. The residue was treated with ethanol to isolate
product XV. Yield 1.2 g (78%), mp 129–131°C (from
propan-2-ol). IR spectrum, ν, cm–1: 1630 (C=N), 1660
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1:1). H NMR spectrum (CF3COOH), δ, ppm: 4.30 s
(1H, CH=N), 4.70 s (2H, 3-CH2), 6.93 d (1H, 4-H, J =
2.2 Hz), 8.03 d (1H, 5-H, J = 2.2 Hz), 7.93–8.40 m
(4H, C6H4). IR spectrum, ν, cm–1: 1620 (C=N), 1670
(C=O). Found, %: C 52.60; H 4.00; N 25.48;
C12H11N5O3. Calculated, %: C 52.75; H 4.06; N 25.63.
1H-Pyrazol-3-ylcarboxylic acid (IX). Potassium
permanganate, 6.0 g (38.0 mmol), was added in por-
tions to a solution of 0.9 g (6.4 mmol) of hydrazide III
in 45 ml of water, heated to 85–90°C, and the mixture
was kept for 2 h at that temperature. The precipitate of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 8 2008