Reaction of 2-hydrazino- and 2-(benzylhydrazino)benzimidazoles with 4-phenyl-3-butyn-2-one [7]

Full text of DOI:10.1023/A:1023995600891

Chemistry of Heterocyclic Compounds, Vol. 39, No. 3, 2003
REACTION OF 2-HYDRAZINO- AND
2-(BENZYLHYDRAZINO)BENZIMIDAZOLES
WITH 4-PHENYL-3-BUTYN-2-ONE
M. V. Povstyanoi, V. P. Kruglenko, and V. M. Povstyanoi
Keywords: 1-benzyl-3-methyl-5-phenyl-1,2,4-triazepino[4,3-a]benzimidazole, 2-hydrazinobenz-
imidazole, 2-(3-methyl-5-phenyl-1-pyrazolyl)benzimidazole, 4-phenyl-3-butyn-2-one, condensation.
In a study of the heterocyclization of hydrazinobenzimidazoles using dinucleophilic reagents [1-4], we
were the first to investigate the reaction of 2-hydrazino- (1a) and 2-benzylhydrazinobenzimidazoles (1b) with
4-phenyl-3-butyn-2-one (2).
Heating equimolar amounts of 1a and 2 in methanol at reflux with base catalysis for 3 h gave
2-(3-methyl-5-phenyl-1-pyrazolyl)benzimidazole (3).
The reaction of benzylhydrazinobenzimidazole 1b with ketone 2 under the same conditions stops at the
formation of the 1-(2-benzimidazolyl)-1-benzylhydrazone of 4-phenyl-3-butyn-2-one (4).
The reaction of 10 mmoles 1b and 15 mmoles 2 in DMF at reflux for 4 h with two or three drops of
triethylamine gave 1-benzyl-3-methyl-5-phenyl-1,2,4-triazepino[4,3-a]benzimidazole (5). Alternatively, 5 was
obtained in 84% yield upon heating hydrazone 4 in DMF at reflux for 2 h.
Ph
NH
MeCC CPh
H
N
O
N
2
N
Me
N
N
NNH2
3
1a,b
R
Ph
Me
N=C–C
N
H
N
Me
C–Ph
N
N
N
N
N
4
5
Bn
Bn
1 a R = H, b R = CH2Ph
Benzimidazole 3 was obtained in 71% yield; mp 250°C (methanol). IR spectrum (KBr), ν, cm-1:
νNH 3080. 1H NMR spectrum (CD3OD), δ, ppm: 2.68 (3H, s, CH3); 6.64 (1H, s, CH); 7.19-7.88 (9H, m, H arom).
Found, %: C 74.40; H 5.02; N 20.30. C17H14N4. Calculated, %: C 74.43; H 5.14; N 20.42.
__________________________________________________________________________________________
Kherson State Technical University, 73008 Kherson, Ukraine; e-mail: lvi@tlc.kherson.ua; e-mail:
kstu@tlk.kherson.ua. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 442-443, March,
2003. Original article submitted January 5, 2003.
398
0009-3122/03/3903-0398$25.00©2003 Plenum Publishing Corporation

Benzimidazole 4 was obtained in 69% yield; mp 137-139°C (toluene). IR spectrum (KBr), ν, cm-1:
νC–N 1230, νC=N 1650, νC≡C 2200, νNH 3050. 1H NMR spectrum (CD3OD), δ, ppm: 2.23 (3H, s, CH3); 5.70 (2H,
s, CH2); 6.98-7.26 (14H, m, H arom). Mass spectrum, m/z (Irel, %): 365 (23), M+ 364 (92), [M-H]+ 363 (100),
[M-CH3]+ 349 (9), [(M-H) - CH3CN]+ 322 (5), [M-C6H5]+ 287 (27), [M-CH2C6H5]+ 273 (11), [(M+H) -
NCH2C6H5]+ 260, 243 (13), [(M+H) - C9H10N2]+ 219 (6), 92 (13), [CH2C6H5]+ 91 (26), [C6H5]+ 77 (5).
Found, %: C 78.95; H 5.32; N 15.30. C24H20N4. Calculated, %: C 79.09; H 5.53; N 15.37.
1
Benzimidazole 5 was obtained in 73% yield; mp 266-267°C (aqueous methanol). H NMR spectrum
(CD3OD), δ, ppm: 2.15 (3H, s, CH3); 2.25 (3H, s, CH3); 5.39 (2H, s, CH2); 7.10-7.45 (14H, m, H arom). Mass
spectrum, m/z (Irel, %): M+ 364 (8), [M-CH2C6H5]+ 273 (11), [M-NC(CH3)C≡CC6H5]+ 222 (5), 93 (5), 92 (62),
[CH2C6H5]+ 91 (100), 56 (9), 34 (13). Found, %: C 78.99; H 5.55; N 15.26. C24H20N4. Calculated, %: C 79.09;
H 5.53; N 15.37.
REFERENCES
1.
2.
N. A. Klyuev, M. V. Povstyanoi, and V. P. Gumennyi, Khim. Geterotsikl. Soedin., 88 (1983).
M. V. Povstyanoi, V. P. Kruglenko, E. N. Fedosenko, and N. A. Klyuev, Khim. Geterotsikl. Soedin., 234
(1990).
M. V. Povstyanoi, E. N. Fedosenko, and V. P. Kruglenko, Ukr. Khim. Zh., No. 10, 1089 (1990).
M. V. Povstyanoi, V. P. Kruglenko, and V. M. Povstyanoi, Khim. Geterotsikl. Soedin., 127 (2001).
3.
4.
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