S. Santra et al. / Tetrahedron Letters 53 (2012) 1974–1977
1977
2
9
009, 74, 3982; (f) Dey, R.; Chattopadhyay, K.; Ranu, B. C. J. Org. Chem. 2008, 73,
461; (g) Moreno-Manas, M.; Pleixats, R. Acc. Chem. Res. 2003, 36, 638; (h)
benzoimidazole (Table 2, entry 11): Brown liquid. 1H NMR (400 MHz, CDCl
7.75–7.73 (m, 1H), 7.31–7.29 (m, 1H), 7.25–7.22 (m, 2H), 4.10 (t, J = 7.6 Hz, 2H),
2.86 (t, J = 7.8 Hz, 2H), 1.96–1.80 (m, 2H), 1.82–1.74 (m, 2H), 1.43–1.37 (m, 2H),
3
): d
Jammi, S.; Sakthivel, S.; Rout, T.; Mandal, S.; Mitra, R.; Saha, P.; Punniyamurthy,
T. J. Org. Chem. 1971, 2009, 74; (i) Reddy, V. P.; Kumar, A. V.; Swapna, K.; Rao, K.
R. Org. Lett. 2009, 11, 1697.
1.07 (t, J = 7.4 Hz, 3H), 0.97 (t, J = 7.4 Hz, 3H); 13C NMR (100 MHz, CDCl
): d
154.8, 141.9, 134.8, 122.1, 121.9, 118.9, 109.4, 43.5, 31.9, 29.2, 21.2, 20.2, 14.1,
13.7. Anal. Calcd for C14 : C, 77.73; H, 9.32; N, 12.95. Found: C, 77.64; H,
9.23; N, 12.84. 1-Isobutyl-2-isopropyl-1H-benzoimidazole (Table 2, entry 12):
Yellow oil. 1H NMR (400 MHz, CDCl
): d 7.78–7.76 (m, 1H), 7.30–7.26 (m, 1H),
7.23–7.20 (m, 2H), 3.92 (d, J = 8 Hz, 2H), 3.22–3.16 (m, 1H), 2.26–2.15 (m, 1H),
1.44 (d, J = 8 Hz, 6H), 0.95 (d, J = 8 Hz, 6H); 13C NMR (100 MHz, CDCl
): d 159.8,
141.9, 134.7, 121.7, 121.5, 118.7, 109.6, 50.5, 34.0, 29.0, 26.0, 21.6, 19.9, 19.0.
Anal. Calcd. for C14 : C, 77.73; H, 9.32; N, 12.95. Found: C, 77.67; H, 9.21;
N, 12.82. 2-Butyl-1-pentyl-1H-benzoimidazole (Table 2, entry 13): Yellow
liquid. 1H NMR (400 MHz, CDCl
): d 7.74–7.72 (m, 1H), 7.30–7.27 (m, 1H),
7.24–7.20 (m, 2H), 4.08 (t, J = 7.4 Hz, 2H), 2.86 (t, J = 7.8 Hz, 2H), 1.89–1.78 (m,
4H), 1.50–1.33 (m, 6H), 1.00–0.88 (m, 6H); 13C NMR (100 MHz, CDCl
): d 155.1,
142.4, 134.9, 122.0, 121.8, 119.5, 109.3, 43.7, 30.0, 29.6, 29.1, 27.1, 22.7, 22.4,
13.9 (2C). Anal. Calcd for C16 : C, 78.64; H, 9.90; N, 11.46. Found: C, 78.51;
H, 9.78; N, 11.35. 1-(3-Phenyl-allyl)-2-styryl-1H-benzoimidazole (Table 2,
3
1
2
9. (a) Rahman, M.; Bagdi, A. K.; Majee, A.; Hajra, A. Tetrahedron Lett. 2011, 52,
20 2
H N
4
437; (b) Kundu, D.; Majee, A.; Hajra, A. Chem. Asian J. 2011, 6, 243; (c) Urinda,
S.; Kundu, D.; Majee, A.; Hajra, A. Heteroat. Chem. 2009, 20, 232; (d) Kundu, D.;
Majee, A.; Hajra, A. Tetrahedron Lett. 2009, 50, 2668.
3
0. Typical procedure for the synthesis of 2-benzo[1,3]dioxol-5-yl-1-
3
benzo[1,3]dioxol-4-yl-methyl-1H-benzoimidazole (Table 2, entry 8):
mixture of o-phenylenediamine (107 mg, 1 mmol) and piperonal (300 mg,
mmol) was stirred in the presence of commercially available nano In
5 mol %) in an EtOH/H O (2:1) mixture (5 ml) at 60 °C for 2 h (TLC). After
completion, the reaction mixture was diluted with a 1:1 mixture of water/ethyl
acetate (10 mL) and nano In was recovered by centrifugation. The reaction
4
SO .
A
20 2
H N
2
(
2 3
O
2
3
2
O
3
3
mixture was extracted with diethyl ether (2 Â 10 mL) and dried over Na
2
Evaporation of solvent furnished the crude product which was recrystallized
from methanol to afford the analytically pure product as a yellow solid
24 2
H N
1
(
342 mg, 92%). Yellow solid. Mp 143–144 °C. IR (KBr) 3434, 2906, 1454,
entry 14): Brown oil. H NMR (500 MHz, CDCl
(d, J = 8 Hz, 1H), 7.60–7.03 (m, 14H), 6.44 (d, J = 15.5 Hz, 1H), 6.36–6.30 (m,
1H), 5.04 (d, J = 4.5 Hz, 1H), 4.99 (d, J = 4 Hz, 1H); 13C NMR (125 MHz, CDCl
): d
3
): d 8.06 (d, J = 16 Hz, 1H), 7.85
À1
1
1
5
2
1
1
7
247 cm
3
. H NMR (500 MHz, CDCl ): d 7.82 (d, J = 8 Hz, 1H), 7.30–7.15 (m,
H), 6.87 (d, J = 8 Hz, 1H), 6.74 (d, J = 8.5 Hz, 1H), 6.56–6.55 (m, 2H), 6.02 (s,
3
1
3
H), 5.93 (s, 2H), 5.34 (s, 2H). C NMR (125 MHz, CDCl
48.1, 147.4, 143.1, 136.1, 130.3, 123.9, 123.7, 123.1, 122.8, 119.9, 119.4, 110.5,
09.8, 108.8, 108.7, 106.7, 101.6, 101.4, 48.3. Anal. Calcd for C22 : C,
0.96; H, 4.33; N, 7.52. Found: C, 70.82; H, 4.26; N, 7.43. 1-Butyl-2-propyl-1H-
3
): d 153.9, 149.2, 148.5,
150.8, 142.3, 138.8, 135.9, 135.8, 135.1, 134.6, 132.8, 130.4, 129.4, 129.1, 129,
128.8, 128.3 (2C), 127.6, 126.7, 123.3, 123.2, 123.1, 119.2, 112.4, 109.8, 45.5.
H
16
2
N O
4
Anal. Calcd for C24
8.24.
20 2
H N : C, 85.68; H, 5.99; N, 8.33. Found: C, 85.54; H, 5.89; N,