ANISIMOVA, TOLPYGIN
1352
2 mmol of imine XIa in 8 ml of boiling anhydrous
toluene over a period of 30 min.
7.0 Hz), 2.43–2.60 m (4H, NCH2), 2.63–2.76 m (2H,
CH2N), 3.33 t (1H, 3-Hax, J = 7.5 Hz), 3.60–3.72 m
(4H, CH2O), 3.80–4.02 m (3H, NCH2, 3-Heq), 4.49–
4.64 m (1H, CH), 6.63–6.95 m (4H, Harom).
9-Benzyl-2-methyl-2,3-dihydroimidazo[1,2-a]-
benzimidazole hydrobromide (XIIb) was obtained
by heating imine XIb for 2 h at 125–130°C. Yield
95%, mp 230–232°C (from EtOH). IR spectrum, ν,
cm–1: 1660, 1600, 1620, 1540, 1500, 1475 (C=C,
C=N). Found, %: C 59.40; H 5.18; Br 23.15; N 12.27.
C17H17N3 ·HBr. Calculated, %: C 59.31; H 5.27;
1-Methyl-3-[(E)-prop-2-en-1-yl]-2,3-dihydro-1H-
benzimidazol-2-imine (XIVa). A solution of 0.9 g
(5 mmol) of imine IXa in 10 ml of a 5% solution of
potassium hydroxide in dimethyl sulfoxide was heated
for 15 min at 100°C. The mixture was cooled, diluted
with 100 ml of water, and extracted with chloroform.
The extract was washed with water and evaporated.
Yield 81%, mp 50–51°C (from petroleum ether). IR
spectrum, ν, cm–1: 3285 (NH); 1660, 1635, 1615, 1500,
1
Br 23.21; N 12.21. H NMR spectrum of free base
XIIb (CDCl3), δ, ppm: 1.37 d (3H, CH3, J = 6.5 Hz),
3.35 t (1H, 3-Hax, J = 6.5 Hz), 3.98 t (1H, 3-Heq, J =
8.6 Hz.), 4.50–4.68 m (1H, CH), 4.94 q (2H, NCH2),
6.54–7.36 m (9H, Harom).
1
1475 (C=C, C=N). H NMR spectrum (CDCl3), δ,
3
4
ppm: 1.89 d.d (3H, CH3, J = 6.8, J = 1.7 Hz), 3.41 s
(3H, NCH3), 5.86–6.08 m (1H, CH), 6.43 d.d (1H,
NCH, 3J = 14.1, 4J = 1.5 Hz), 6.65–7.10 m (4H, Harom).
Found, %: C 70.49; H 7.05; N 22.46. C11H13N3. Cal-
culated, %: C 70.56; H 7.00; N 22.44.
After prolonged heating, a mixture of two isomers
was formed with gradually increasing fraction of
1-methyl-3-[(Z)-prop-2-en-1-yl]-2,3-dihydro-1H-benz-
imidazol-2-imine (XIIIa). 1H NMR spectrum (CDCl3),
δ, ppm: 1.65 d.d (3H, CH3, 3J = 7.1, 4J = 1.7 Hz), 3.34 s
(3H, NCH3), 5.86–6.08 m (1H, CH), 6.15 d.d (1H,
NCH, 3J = 7.5, 4J = 1.5 Hz), 6.65–7.10 m (4H, Harom).
9-(2-Diethylaminoethyl)-2-methyl-2,3-dihydro-
imidazo[1,2-a]benzimidazole dihydrochloride
(XIIc). Hydrobromide Xc, 5.2 g (10 mmol), was dis-
solved in 25 ml of water, 5 ml of 22% aqueous am-
monia was added, and the free base was extracted into
chloroform (2×25 ml). The extracts were combined,
dried over Na2SO4, and evaporated, and the residue
was heated in 25 ml of boiling toluene until the reac-
tion was complete (TLC, Al2O3, CHCl3). The mixture
was then treated with water (2×15 ml), the aqueous
extracts were combined and made alkaline by adding
aqueous ammonia, and free base XIIc was extracted
into chloroform (3×10 ml). The extracts were com-
bined and passed through a layer of Al2O3 (3×4 cm),
the sorbent was eluted with chloroform, the eluate was
evaporated, and the residue was dissolved in 15–20 ml
of acetone and acidified to pH 2–3 with a solution of
HCl in isopropyl alcohol. Yield 41%, mp 241–242°C
(decomp., from MeCN or EtOH). IR spectrum, ν, cm–1:
1660, 1620, 1600, 1540, 1500, 1475 (C=C, C=N).
Found, %: C 55.74; H 7.65; Cl 20.43; N 16.18.
C16H24N4 ·2HCl. Calculated, %: C 55.65; H 7.59;
3-Benzyl-1-(prop-2-en-1-yl)-2,3-dihydro-1H-
benzimidazol-2-imine (XIIIb/XIVb, a mixture of cis
and trans isomers). Isomer mixture XIIIb/XIVb was
synthesized according to the procedure described
1
above for isomers of XIVa. H NMR spectrum
3
(CDCl3), δ, ppm: cis isomer: 1.69 d.d (3H, CH3, J =
4
6.8, J = 1.6 Hz), 5.10 s (2H, CH2Ph), 5.88–6.12 m
3
4
(1H, CH), 6.21 d.d (1H, NCH, J = 8.7, J = 1.5 Hz),
6.67–7.43 m (9H, Harom); trans isomer: 1.91 d.d (3H,
CH3, 3J = 7.7, 4J = 1.6 Hz), 5.04 s (2H, CH2Ph), 5.88–
3
4
1
6.12 m (1H, CH), 6.49 d.d (1H, NCH, J = 13.7, J =
Cl 20.53; N 16.23. H NMR spectrum of the free base
1.5 Hz), 6.67–7.43 m (9H, Harom).
(CDCl3), δ, ppm: 0.98 t (6H, CH3, J = 7.2 Hz), 1.37 d
(3H, CH3, J = 7.1 Hz), 2.50–2.67 m (6H, CH2N), 2.76 t
(2H, NCH2, J = 7.2 Hz), 3.32 t (1H, 3-Hax, J = 7.9 Hz),
3.70–4.05 m (3H, NCH2, 3-Heq), 4.50–4.67 m (1H,
CH), 6.62–6.96 m (4H, Harom).
REFERENCES
1. Anisimova, V.A., Tolpygin, I.E., and Borodkin, G.S.,
Russ. J. Org. Chem., 2010, vol. 46, p. 275.
2-Methyl-9-(2-morpholinoethyl)-2,3-dihydro-
imidazo[1,2-a]benzimidazole dihydrochloride
(XIId) was synthesized as described above for dihy-
drochloride XIIc. Yield 47%, mp 237–238°C (decomp.,
from EtOH). IR spectrum, ν, cm–1: 1660, 1610, 1500,
1475 (C=C, C=N). Found, %: C 53.58; H 6.65;
Cl 19.82; N 15.51. C16H22N4O·2HCl. Calculated, %:
C 53.49; H 6.73; Cl 19.73; N 15.59. 1H NMR spectrum
of the free base (CDCl3), δ, ppm: 1.36 d (3H, CH3, J =
2. Ernst, S., Jelonek, S., Sieler, J., and Schulze, K., Tetra-
hedron, 1996, vol. 52, p. 791.
3. Strzemecka, L., Polish J. Chem., 1983, vol. 57, p. 567.
4. Ulsaker, G.A. and Undheim, K., Acta Chem. Scand.,
Ser. B, 1975, vol. 29, p. 853.
5. Martin, D.M.G. and Reese, C.B., J. Chem. Soc. C, 1968,
p. 1731.
6. Kamal, A., Rao, M.V., and Rao, A.B., J. Chem. Soc.,
Perkin Trans. 1, 1990, p. 2755.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 9 2011