814
Vol. 39
M. Amari, M. Fodili, B. Nedjar-Kolli, P. Hoffmann and J. Périé
4-(2-Amino-5-nitroanilino)-6-methyl-5,6-dihydro-2H-2-pyra-
none (2d).
6.24 (s, 1H, C -H), 7.18-7.76 (m, 4H, Ar), 8.05 (s, 1H, C -H);
3 2
13
C nmr (dimethyl sulfoxide-d ): δ 20.1 (CH ), 32.4 (C ), 72.7
6
3
5
(C ), 103.9 (C ), 113.3, 120.3, 123.7, 124.4 (Ar-C), 131.4 (C ),
6
3
3a
Compound 2d was obtained in 60% yield, mp 198-200 °C; ir:
144.4 (C ), 150.1 (C ), 164.8 (C ). ms: (70 eV, electron impact)
7a
4
2
-1
1
1660 (C=O), 3340 (NH), 3340-3380 (NH ) cm
H nmr
2
;
m/z 228 (molecular ion).
(dimethyl sulfoxide-d ): δ 1.25 (d, J = 6 Hz, 3H, CH ), 2.44-2.60
6
3
Anal. Calcd for C H N O : C, 68.41; H, 5.30; N, 12.27.
13 12
2 2
(m, 2H, CH ), 4.26 (s, 1H, C -H), 4.43-4.52 (m, 1H, C -H), 6.60
2
3
6
Found: C, 68.44; H, 5.42; N, 12.28.
13
(s, 2H, NH ), 6.80-7.97 (m, 3H, Ar), 8.44 (s, 1H, NH); C nmr
2
(dimethyl sulfoxide-d ): δ 20.8 (C H ), 34.0 (C ), 71.6 (C ),
4-(5-Methyl-1H-benzo[d]imidazol-1-yl)-6-methyl-5,6-dihydro-
2H-2-pyranone (3b).
6
(6)
3
5
6
83.8 (C ), 121.4 (C-NH ), 124.5, 124.6, 125.0 (Ar-C), 135.9 (Ar-
3
2
C), 151.5 (Ar-C-N), 159.3 (C ), 167.5 (C ).
4
2
Compound 3b was obtained in 65% yield, mp 201-204 °C; ir:
4-(2-Aminoanilino)-2,5-dihydro-2-furanone (2e).
-1
1
CO 1645 cm ; H nmr): δ 1.52 (d, J = 6 Hz, 3H, CH ), 2.49
3
(s, 3H, CH ), 2.95-2.98 (m, 2H, CH ), 4.75-4.79 (m, 1H, C -H),
Compound 2e was obtained in 70% yield, mp 217-219 °C; ir:
3
2
6
13
-1
1
6.24 (s, 1H, C -H), 7.17-7.58 (m, 3H, Ar); C nmr (dimethyl
1670 (C=O), 3330 (NH), 3350-3380 (NH ) cm
H nmr
3
2
;
(dimethyl sulfoxide-d ): δ 4.26 (s, 1H, C -H), 4.81 (s, 2H, CH ),
sulfoxide-d ): δ 20.1 (C H ), 20.8 (C H ), 32.3 (C ), 72.7
6
3
2
6
(6)
3
(5)
3
5
13
5.02 (s, 2H, NH ), 6.53-7.07 (m, 4H, Ar), 8.70 (s, 1H, NH);
C
(C ), 103.4 (C ), 112.9, 120.2, 125.4 (Ar-C), 129.4 (C ), 133.2
2
6
3
3a
nmr (dimethyl sulfoxide-d ): δ 67.3 (C ), 81.0 (C ), 115.5, 116.2,
(C ), 142.5 (C ), 144.8 (C ), 150.1 (C ), 164.9 (C ). ms: (70 eV,
6
5
3
5
2
7a
4
2
124.0, 126.4 (Ar-C), 142.2 (Ar-C-N), 166.6 (C ), 174.8 (C ).
4
2
electron impact) m/z 242 (molecular ion).
Anal. Calcd for C H N O : C, 69.41; H, 5.82; N, 11.56; O,
14 14
2 2
4-(2-Amino-4-methylanilino)-2,5-dihydro-2-furanone (2f).
Compound 2f was obtained in 75% yield, mp 225-227 °C; ir:
13.21. Found: C, 69.43; H, 5.83; N, 11.37.
-1
1
4-( 6-Chloro-1H-benzo[d]imidazol-1-yl)-6-methyl-5,6-dihydro-
2H-2-pyranone (3c).
1670 (C=O), 3320 (NH), 3340-3360 (NH ) cm
H nmr
2
;
(dimethyl sulfoxide-d ): δ 2.18 (s, 3H, CH ), 4.51 (s, 1H, C -H),
6
3
3
4.79 (s, 2H, CH ), 4.93 (s, 2H, NH ), 6.37-6.93 (m, 3H, Ar),
2
2
Compound 3c was obtained in 70% yield, mp 209-210 °C; ir:
13
8.60 (s, 1H, NH); C nmr (dimethyl sulfoxide-d ): δ 20.7
6
-1
1
CO 1668 cm ; H nmr (dimethyl sulfoxide-d ): δ 1.44 (d, J = 6
6
(C H ), 67.3 (C ), 80.7 (C ), 115.9, 117.0 (Ar-C), 121.6
(4)
3
5
3
Hz, 3H, CH ), 2.40-2.50 (m, 2H, CH ), 4.72-4.81 (m, 1H, C -H),
3
2
6
(Ar-NH ), 124.2 (Ar-C), 135.7 (Ar-C ), 142.1 (Ar-C-N), 166.9
2
4
6.36 (s, 1H, C -H), 7.39-8.08 (m, 3H, Ar), 8.80 (s, 1H, C -H);
3
2
(C ), 174.8 (C ).
4
2
13
C nmr (dimethyl sulfoxide-d ): δ 20.0 (C H3), 32.4 (C ), 72.8
6
(6)
5
4-(2-Amino-5-chloroanilino)-2,5-dihydro-2-furanone (2g).
(C ), 104.7 (C ), 114.6, 119.8, 124.4 (Ar-C), 128.0 (C ), 130.2
6
3
3a
(C ), 145.3 (C ), 149.7 (C ), 164.7 (C ). ms: (70 eV, electron
Compound 2g was obtained in 65% yield, mp 233-235 °C; ir:
6
7a
4
2
-1
1
impact) m/z 262 (molecular ion).
Anal. Calcd for C H ClN O : C, 59.44; H, 4.19; Cl, 13.50;
1680 (C=O), 3310 (NH), 3320-3360 (NH ) cm
H nmr
;
2
(dimethyl sulfoxide-d ): δ 4.58 (s, 1H, C -H), 4.81 (s, 2H, CH ),
13 11
2 2
6
3
2
C
13
N, 10.66. Found: C, 59.16; H, 4.19; Cl, 13.54; N,10.65.
5.26 (s, 2H, NH ), 6.54-7.06 (m, 3H, Ar), 8.69 (s, 1H, NH);
2
nmr (dimethyl sulfoxide-d ): δ 67.4 (C ), 81.6 (C ), 114.4, 115.5
6
5
3
4-( 2-Methyl-1H-benzo[d]imidazol-1-yl)-6-methyl-5,6-dihydro-
2H-2-pyranone (3d).
(Ar-C), 121.6 (C-NH ), 125.6 (Ar-C), 130.4 (Ar-C ), 143.9
2
4
(Ar-C-N), 166.3 (C ), 174.7 (C ).
4
2
Compound 3d was obtained in 60% yield, mp 172-174 °C;
4-(2-Amino-5-nitroanilino)-2,5-dihydro-2-furanone (2h).
-1
1
ir: CO 1640 cm
; H nmr (dimethyl sulfoxide-d ): δ 1.5
6
Compound 2h was obtained in 60% yield, mp 250-252 °C; ir:
(d, J = 6 Hz, 3H, CH ), 2.6 (s, 3H, CH ), 2.6-2.9 (m, 2H,
3
3
-1
1
1680 (C=O), 3330 (NH), 3330-3350 (NH ) cm
H nmr
;
2
CH ), 4.7-4.8 (m, 1H, C -H), 6.0 (s, 1H, C -H), 7.2-7.3
2
6
3
(dimethyl sulfoxide-d ): δ 4.64 (s, 1H, C -H), 4.88 (s, 2H, CH ),
13
6
3
2
C
(m, 4H, Ar), 7.7 (s, 1H, C -H); C nmr (dimethyl sulfox-
2
13
6.62 (s, 2H, NH ), 6.76-7.95 (m, 3H, Ar), 8.96 (s, 1H, NH);
2
ide-d ): δ 15.9 (C H ), 20.9 (C H ), 35.1 (C ), 74.2 (C ),
6
(2)
3
(6)
3
5
6
nmr (dimethyl sulfoxide-d ): δ 67.4 (C ), 82.4 (C ), 113.8, 121.2,
6
5
3
101.1 (C ), 110.9, 115.5, 120.1, 123.9 (Ar-C), 134.2 (C ),
3
3a
122.5, 123.7 (Ar-C), 135.6 (Ar-C ), 149.7 (Ar-C-N), 166.5 (C ),
2
4
143.3 (C ), 150.48 (C ), 164.55 (C ). ms: (70 eV, electron
7a
4
2
174.5 (C-NH ).
2
impact) m/z 242 (molecular ion).
Anal. Calcd for C H N O : C, 69.41; H, 5.82; N, 11.56; O,
General Procedure for the Synthesis of Benzimidazoles 3.
14 14
2 2
13.21. Found: C, 69.43; H, 5.83; N, 11.37.
A solution of 2 (2 mmoles) and N,N-dimethylformamide
dimethyl acetal or N,N-dimethylacetamide dimethyl acetal
(2 mmoles) in dry dichloromethane (60 ml) and glacial acetic
acid (100 µl) was heated to reflux under magnetic stirring for six
hours. Evaporation of dichloromethane in vacuo and recrystal-
lization from ethanol gave compounds 3a-3i.
4-(2,5-Dimethyl- 1H-benzo[d]imidazol-1-yl)-6-methyl-
5,6-dihydro-2H-2-pyranone (3e).
Compound 3e was obtained in 62% yield, mp 178-180 °C; ir:
-1
1
CO 1650 cm ; H nmr (dimethyl sulfoxide-d ): δ 1.56 (d, J = 6
6
Hz, 3H, CH ), 2.45 (s, 3H, CH ), 2.62 (s, 3H, CH ), 2.81-2.85
3
3
3
4-(1H-Benzo[d]imidazol-1-yl)-6-methyl-5,6-dihydro-2H-2-
pyranone (3a).
(m, 2H, CH ), 4.89-4.96 (m, 1H, C -H), 6.10 (s, 1H, C -H),
2
6
3
7.11-7.22 (m, 3H, Ar), 7.47 (s, 1H, C -H); ms: (70 eV, electron
2
impact) m/z 256 (molecular ion).
Compound 3a was obtained in 80% yield, mp 172-174 °C; ir:
-1 1
Anal. Calcd for C H N O : C, 70.29; H, 6.29; N, 10.93.
CO 1640 cm
H nmr (dimethyl sulfoxide-d ): δ 1.49 (d, J = 6
15 16
2 2
;
6
Hz, 3H, CH ), 2.86-3.02 (m, 2H, CH ), 4.62-4.80 (m, 1H, C -H),
Found: C, 70.30; H, 6.24; N, 10.92.
3
2
6