SMOLYAR et al.
1192
1,3-Dialkyl-1,3-dihydro-5-(pyrrol-1-yl)benzimid-
azol-2-ones IVa–IVc. To a dispersion of 1.2 mmol of
compound IIIa–IIIc in 2–3 ml of glacial acetic acid was
added 1.2 mmol of 2,5-dimethoxytetrahydrofuran, then
the mixture was heated for 0.5 h at 130°C, the excess
acetic acid was distilled off to dryness, the residue was
ground in warm hexane. The precipitate was filtered off
and recrystallized from an appropriate solvent.
H 5.51; N 17.69. C11H13N3O3. Calculated, %: C 56.16;
H 5.57; N 17.86.
1,3-Dibenzyl-5-nitro-1,3-dihydrobenzimidazol-
2-one (IIc). In 10 ml of 20% water solution of NaOH
was dissolved 4.5 g (2.5 mmol) of 5-nitro-1,3-dihydro-
benzimidazol-2-one (I) at room temperature. At stirring
14.5 g (58.5 mmol) of benzyldimethylphenylammonium
chloride in 15 ml of water was added, the mixture was
heated at boiling for 7 h, N,N-dimethyaniline was re-
moved by steam distillation. On cooling the separated
precipitate was filtered off, washed with cold water, dried,
and crystallized from 2-propanol. Yield 5.0 g (57%),
1,3-Dimethyl-1,3-dihydro-5-(pyrrol-1-yl)benz-
imidazol-2-one (IVa). Yield 66%, mp 151–152°C
1
(heptane). H NMR spectrum (CDCl3), δ, ppm: 3.45 s
(6H, N1CH3, N3CH3), 6.35 t ( 2H, H3’,4’), 6.98 d (1H,
H7, J 8.0 Hz), 6.99 s (1H, H4), 7.04 t (2H, H2’,5’),
7.13 d (1H, H6, J 8.0 Hz). Found, %: C 68.54; H 5.71;
N 18.37. C13H13N3O. Calculated, %: C 68.71; H 5.77;
N 18.49.
1
mp 164–166°C. H NMR spectrum (CDCl3), δ, ppm:
5.16 s (4H, N1CH2C6H5, N3CH2C6H5), 6.90 d (1H, H7,
J 8.6 Hz), 7.23–7.31 m (10H, N1CH2C6H5, N3CH2C6H5),
7.77 s (1H, H4), 7.97 d (1H, H6, J 8.6 Hz). Found, %:
C 70.12; H 4.71; N 11.54. C21H17N3O3. Calculated, %:
C 70.18; H 4.77; N 11.69.
1,3-Diethyl-1,3-dihydro-5-(pyrrol-1-yl)benzimid-
azol-2-one (IVb). Yield 48%, mp 115–117°C (heptane).
1H NMR spectrum (CDCl3), δ, ppm: 1.40 t (6H,
N1CH2CH3, N3CH2CH3), 4.00 q (4H, N1CH2CH3,
N3CH2CH3), 6.40 t (2H, H3’,4’), 7.05 d (1H, H7, J 8.5 Hz),
7.06 s (1H, H4), 7.08 t (2H, H2’,5’), 7.15 d (1H, H6,
J 8.5 Hz). Found, %: C 70.52; H 6.65; N 16.30.
C15H17N3O. Calculated, %: C 70.56; H 6.71; N 16.46.
5-Amino-1,3-dialkyl-1,3-dihydrobenzimidazol-2-
ones IIIa–IIIc. To 25 mmol of compound IIa–IIc was
added 30 ml of hydrazine hydrate, and the reaction mix-
ture was heated in an argon flow for 14 h at 115–120°C.
Then excess hydrazine hydrate was distilled off, the
residue was dissolved in water and cooled. The separated
precipitate was filtered off, dried, and recrystallized from
an appropriate solvent.
1,3-Dibenzyl-1,3-dihydro-5-(pyrrol-1-yl)-benz-
5-Amino-1,3-dimethyl-1,3-dihydrobenzimidazol-
2-one (IIIa). Yield 43%, mp 135–136°C (benzene).
1H NMR spectrum (CDCl3), δ, ppm: 3.40 s ( 3H, N1CH3),
3.41 s ( 3H, N3CH3), 5.21 br.s (2H, NH2), 6.42 s (1H,
H4), 6.50 d (1H, H7, J 8.2 Hz), 6.80 d (1H, H6, J 8.2 Hz).
Found, %: C 60.83; H 6.21; N 23.56. C9H11N3O. Calcu-
lated, %: C 61.00; H 6.26; N 23.71.
imidazol-2-one (IVc). Yield 52%, mp 165–168°C
(2-пpOпaHOл). H NMR spectrum (CDCl3), δ, ppm:
1
5,20 s (4H, N1CH2C6H5, N3CH2C6H5), 6.27 t (2H, H3’,4’),
6.95 d (1H, H7, J 8.5 Hz), 7.35 t (2H, H2’,5’), 7.40 br.s
(10H, N1CH2C6H5, N3CH2C6H5), 7.82 s (1H, H4), 8.02 d
(1H, H6, J 8.5 Hz). Found, %: C 78.97; H 5.52; N 10.95.
C25H21N3O. Calculated, %: C 79.13; H 5.58; N 11.07.
5-Amino-1,3-diethyl-1,3-dihydrobenzimidazol-
2-one (IIIb). Yield 63%, mp 175–176°C (benzene).
1H NMR spectrum (DMSO-d6), δ, ppm: 1.28 t (6H,
N1CH2CH3, N3CH2CH3), 3.85 q (4H, N1CH2CH3,
N3CH2CH3), 6.43 d (1H, H7, J 8.2 Hz), 6.52 s (1H, H4),
6.89 d (1H, H6, J 8.2 Hz). Found, %: C 64.25; H 7.31;
N 20.31. C11H15N3O. Calculated, %: C 64.37; H 7.37;
N 20.47.
1-(1,3-Dialkyl-2-oxo-1,3-dihydrobenzimidazol-5-
yl)-2,6-dimethylpyridin-4-ones Va–Vc. A mixture of
10 mmol of 5-amino-1,3-dialkyl-1,3-dihydrobenzimid-
azol-2-one IIIa–IIIc and 10 mmol of 2,6-dimethyl-γ-
pyranone was heated at 120–125°C over 6–8 h. On cool-
ing the melt was ground in petroleum ether (bp 60–80°C),
the precipitate was isolated and crystallized from heptane.
1-(1,3-Dimethyl-2-oxo-1,3-dihydrobenzimidazol-
5-Amino-1,3-dibenzyl-1,3-dihydrobenzimidazol-
2-one (IIIc). Yield 67%, mp 132–134°C (2-propanol).
1H NMR spectrum (CDCl3), δ, ppm: 5.10 br.s (2H, NH2),
5.20 s (4H, N1CH2C6H5, N3CH2C6H5), 6.29 s (1H, H4),
6.35 d (1H, H7, J 8.2 Hz), 6.60 d (1H, H6, J 8.2 Hz), 7.32 s
(10H, N1CH2C6H5, N3CH2C6H5). Found, %: C 76.46;
H 5.74; N 12.63. C21H19N3O. Calculated, %: C 76.57;
H 5.81; N 12.76.
5-yl)-2,6-dimethylpyridin-4-one (Va). Yield 78%, mp
1
90–92°C. H NMR spectrum (CDCl3), δ, ppm: 2.28 s
(6H, C2'CH3, C6'CH3), 3.38 s (3H, N1'CH3), 3.39 s (3H,
N3'CH3), 6.10 s (2H, H3',5'), 6.41 s (1H, H4), 6.49 d (1H,
H7, J 8.2 Hz), 6.78 d (1H, H6, J 8.2 Hz). Found, %:
C 67.66; H 5.98; N 14.64. C16H17N3O2. Calculated, %:
C 67.83; H 5.05; N 14.83.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 8 2011