1
δ
J
4J =
(octane). H NMR spectrum (CDCl3), , ppm, (Hz): 1.90 (3H, s, COCH3); 2.30 (1H, t,
2.4, CH); 4.30 (1H,
17.4, CH2); 7.36 (3H, m, 4-, 6-H); 7.83 (1H, m, 7-H);
8.06 (1H, s, 2-H). Found, %: C 67.95, H 5.41; N 19.60. C12H11N3O. Calculated, %: C 67.59; H 5.20; N 19.71.
1-(Propargylamino)benzimidazole (1g). 10b
4J = 2J = 4J = 2J =
dd,
2.4,
17.5, CH2); 5.05 (1H, dd,
2.4,
A solution of
(0.5 g, 2.3 mmol) was refluxed in H2SO4
(5%, 25 ml) for 1.5 h. With cooling, it was neutralized using concentrated ammonia to pH 7-8. The reaction
product was extracted with chloroform (3 × 5 ml). The chloroform solution was passed through an Al2O3
l
d
Rf
column ( = 20 cm, = 1.5 cm) using chloroform eluent. The fraction with 0.35 was collected to give
1
1g
δ
compound
(Hz): 2.40 (1H, t,
(0.35 g, 87%) as colorless crystals; mp 88-91°C (octane). H NMR spectrum (CDCl3), , ppm,
J
4J =
2.4, CH); 3.90 (2H, s, –CH2); 5.10 (1H, br. s, NH, disappearing upon deuteration); 7.35
(2H, m, 5-, 6-H); 7.50 (1H, m, 4-H); 7.78 (1H, m, 7-H); 8.10 (1H, s, 2-H). Found, %: C 70.39; H 5.02; N 24.66.
C10H9N3. Calculated, %: C 70.16, H 5.20; N 24.54.
1-[(2-Chloroallyl)amino]benzimidazole (11).
10b
(0.4 g, 1.9 mmol) in HCl
A solution of compound
(5%, 15 ml) was refluxed for 1.5 h. With cooling, it was neutralized using concentrated ammonia to pH 7-8. The
reaction product was extracted with chloroform (3 × 5 ml). The chloroform solution was passed through an
l
d
Rf
Al2O3 column ( = 20 cm, = 1.5 cm) using chloroform eluent. The fraction with 0.45 was collected to give
-1
11
ν
compound
(0.36 g, 93%) as a light yellow oil. IR spectrum (CHCl3), , cm : 3300 (NH), 2970 (C–H arom.)
1
δ
J
3J =
1620, 1580, 1500 (ring). H NMR spectrum (CDCl3), , ppm, (Hz): 3.90 (2H, d,
2.8, –CH2); 5.20 (1H, t,
4Jcis = 0.7, =CH2); 5.30 (1H, d, Jtrans = 1.7, =CH2); 5.04 (1H, br. s, NH, disappearing upon deuteration); 7.30
4
(2H, m, 5-, 6-H); 7.50 (1H, m, 4-H); 7.78 (1H, m, 7-H); 8.10 (1H, s, 2-H). Found, %: C 58.07; H 5.03; Cl 17.32;
N 20.38. C10H10ClN3. Calculated, %: C 57.84; H 4.85; Cl 17.07; N 20.23.
General Method for Preparation of 1-(Nitrosoalkylamino)benzimidazoles (2).
A solution of an
1f 1g
(2%)
equimolar amount of sodium nitrite in water was added dropwise to a solution of compound
or
cooled to -5°C at such a rate that the temperature did not exceed 0°C. The pale yellow mixture was held for
30 min at -5 to 0°C, after which it was neutralized with concentrated ammonia to pH 7-8 and the emulsion
formed was extracted with chloroform (10 ml). The chloroform solution was passed through an Al2O3 column
l
d
Rf
( = 20 cm, = 1.0 cm) using chloroform eluent. The fraction with
0.7 was collected. The chloroform was
as oils which were used without additional
2f,g
evaporated off and the residue evacuated to give compounds
purification.
1-(N-nitrosoallylamino)benzimidazole (2f)
1f
(0.1 g, 0.58 mmol) as a
was prepared from compound
1
δ
E
pale yellow oil in 0.054 g (46%) yield. H NMR spectrum (CDCl3), , ppm: 4.61 (2H, br. s, –CH2, ); 5.25 (6H,
m, –CH2 Z
E
Z
E
Z
Z
, CH2= , CH2= ); 5.65 (1H, m, –CH– ); 6.04 (1H, m, –CH– ); 7.02 (1H, m, 4-H ); 7.32 (5H, m,
1
E
Z
Z
E
Z
E
4-, 6-H , 5-, 6-H ); 7.61 (1H, s, 2-H ); 7.82 (2H, m, 7-H , 7-H ); 8.05 (1H, s, 2-H ). H NMR spectrum
δ
J
3J =
E Z E Z
6.6, CH2– ); 5.31 (6H, m, CH2– , CH2= , CH2= ); 5.75 (1H,
(DMSO-d6), , ppm (Hz): 4.78 (2H, d,
E
Z
E
Z
Z
E
m, CH– ); 6.18 (1H, m, CH– ); 7.30 (4H, m, 5-, 6-H , 5-, 6-H ); 7.40 (1H, m, 4-H ); 7.56 (1H, m, 4-H );
Z
E
Z
E
7.75 (1H, m, 7-H ); 7.82 (1H, m, 7-H ); 8.20 (1H, s, 2-H ); 8.73 (1H, s, 2-H ). Found, %: C 59.83; H 5.22;
N 27.50. C10H10N4O. Calculated, %: C 59.40; H 4.98; N 27.71.
1-(N-Nitrosopropargylamino)benzimidazole (2g)
1g
(0.05 g, 0.3 mmol)
was prepared from compound
1
δ
Z
as a light yellow oil (0.02 g, 34%). H NMR spectrum (DMSO-d6), , ppm: 3.67 (1H, br. s, CH– ); 5.05 (2H, s,
E
Z
Z
E
E
Z
CH2 ); 5.82 (2H, s, CH2 ); 7.36 (5H, m, 5-, 6-H 4-, 6-H ); 7.56 (1H, m, 7-H ); 7.80 (2H, m, 4-, 7-H );
Z
E
8.23 (1H, s, 2-H ); 8.73 (1H, s, 2-H ). Found, %: C 60.15; H 4.37; N 28.34. C10H8N4O. Calculated, %:
C 59.99; H 4.03; N 27.99.
1-(Tosylamino)benzimidazole (12).
A mixture of 1-aminobenzimidazole (0.133 g, 1 mmol) and
p
-toluenesulfonyl chloride (0.191 g, 1 mmol) was held for 1 h at 100-110°C. After cooling, the melt was
triturated with a mixture of methanol and diethyl ether (1:10, 10 ml) and the precipitate was filtered off to give
1
12
compound
(0.168 g, 60%) as light grey crystals; mp 240-242°C (decomp.; from methanol). H NMR
δ
J
spectrum (DMSO-d6), , ppm, (Hz): 2.39 (3H, s, CH3); 5.60 (1H, s, NH); 6.96 (1H, m, 4-H) 7.16 (1H, dt,
963