1
2
V. Abbhi et al. / Bioorganic & Medicinal Chemistry xxx (2017) xxx–xxx
the mixture was further refluxed for 1 h. Subsequently, various
substituted piperazines such as 1-methylpiperazine, 1-ethylpiperazine,
12.12 (br s, 1H, -NH) ppm. 13C NMR (DMSO d
60.77, 106.77, 112.86, 115.03, 120.96, 135.11, 137.17, 145.87,
147.35, 158.76 and 169.16 ppm. FT-IR max (KBr): 3352.13,
3163.33, 2832.06, 1687.35, 1630.90, 1583.06, 1529.37, 1442.02,
6
): d 44.59, 52.42,
1
-phenylpiperazine, 1-(2-fluorophenyl)piperazine, 1-pyridylpiper-
m
azine, 1-pyrimidylpiperazine, 1-benzylpiperazine, 1-benzhydryl-
piperazine, 1-(4-methoxyphenyl)piperazine, 1-(4-nitrophenyl)
piperazine, 1-{4-(furan-2-carbonyl)}piperazine, 1-(2-methoxyphe-
nyl)piperazine and 1-phenethylpiperazine were added in equimo-
lar quantities (1.91 mmol) to the refluxing solution. The slurry
obtained was filtered and the filtrate was evaporated under
reduced pressure to obtain a solid residue which was recrystallized
from appropriate solvent to afford the purified compounds 9a–m.
ꢀ1
+
1371.33, 1248.77 and 767.06 cm . ESI-MS: 337.5 [M+H] . Anal.
O: C, 64.27; H, 5.99; N, 24.98%. Found: C, 64.43; H,
6.39; N, 25.21%.
18 20 6
C H N
4
1
.1.3.6. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-pyrimidin-2-yl)piperazin-
1
-yl)acetamide (9f). H NMR (DMSO d
6
): d 2.68 (t, 4H, -(CH
), 3.83 (t, 4H, -(CH
2
)
)
2
,
,
piperazine, J = 4.98 Hz), 3.41 (s, 2H, -COCH
piperazine, J = 4.90 Hz), 6.67 (t, ArH, J
= 3.2 Hz), 7.50 (q, 2H, ArH, J = 3.30 Hz), 8.40 (d, 2H, ArH, J
.68 Hz), 11.32 (br s, 1H, -NH) and 12.20 (br s, 1H, -NH) ppm.
2
2
2
o
= 4.7 Hz), 7.14 (q, 2H, ArH,
4
.1.3.1. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-methylpiperazin-1-yl)ac-
J
m
m
o
1
=
C
1
etamide (9a). H NMR (DMSO d
6
): d 2.30 (s, 3H, -CH
, piperazine), 2.66 (s, 4H, -(CH , piperazine), 3.26 (s, 2H,
), 7.22 (m, 2H, ArH), 7.49 (m, 2H, ArH) and 11.03 (br s,
3
), 2.48 (s, 4H,
3
4
-(CH
2
)
2
2 2
)
NMR (DMSO d
6
): d 43.29, 52.18, 60.44, 110.10, 115.13, 121.04,
max (KBr):
340.76, 3027.17, 2923.48, 1784.36, 1691.52, 1632.50, 1581.95,
-COCH
2
1
3
1
3
35.49, 146.05, 157.90, 161.15 and 169.48 ppm. FT-IRm
1
3
2
1
3
1
H, -NH) ppm. C NMR (DMSO d
17.98, 122.32, 135.24, 145.92 and 170.63 ppm. FT-IR
347.49, 3040.01, 2801.34, 1698.81, 1638.96, 1587.01, 1527.28,
6
): d 45.93, 53.56, 54.88, 61.29,
m
max (KBr):
ꢀ1
494.88, 1450.96, 1359.29, 1257.56 and 735.66 cm . ESI-MS:
+
19 7
38.5 [M+H] . Anal. C17H N O: C, 60.52; H, 5.68; N, 29.06%.
ꢀ1
455.75, 1368.56, 1206.07 and 741.94 cm
.
ESI-MS: 274.6
Found: C, 60.32; H, 5.45; N, 29.45%.
+
[
M+H] . Anal. C14
H
19
N
5
O: C, 61.52; H, 7.01; N, 25.62%. Found: C,
6
1.73; H, 7.14; N, 26.03%.
4
.1.3.7. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-benzylpiperazin-1-yl)ac-
1
4
.1.3.2. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-ethylpiperazin-1-yl)ac-
etamide (9g). H NMR (DMSO d
piperazine), 2.58 (s, 4H, -N(CH
-NHCOCH -), 3.47 (s, 2H, -CH -, benzylic), 7.08 (dd, 2H, ArH,
= 5.94 Hz, J = 3.18 Hz), 7.24 (m, 1H, ArH), 7.30 (m, 4H, ArH),
7.44 (dd, 2H, ArH, J = 5.48 Hz, J = 3.36 Hz), 11.12 (br s, 1H,
NHCOCH -) and 12.07 ppm (br s, 1H, -NH, imidazole ring).
NMR (DMSO d ): d 52.52, 52.55, 60.50, 61.99, 114.23, 121.04,
126.87, 128.13, 128.78, 135.88, 138.15, 145.97, 169.47 ppm.
FT-IR max (KBr): 3355.67, 3031.98, 2937.87, 2815.83, 1687.40,
1632.73, 1574.75, 1525.91, 1453.56, 1269.35, 1137.63 and
6
): d 2.42 (s, 4H, -N(CH
2 2
) -,
1
etamide (9b). H NMR (DMSO d
6
): d 1.10 (t, 3H, -CH
, J = 7.24 Hz), 2.62 (m, 8H, piperazino protons),
.26 (s, 2H, -COCH ), 7.23 (d, 2H, ArH, J = 4.48 Hz), 7.40 (s, ArH),
.59 (s, ArH), 10.18 (br s, 1H, -NH) and 10.91 (br s, 1H, -NH)
3
, J = 7.24 Hz),
2 2
) -, piperazine), 3.27 (s, 2H,
2
3
7
.45 (q, 2H, -CH
2
2
2
J
o
m
2
o
o
m
1
3
13
ppm. C NMR (DMSO d
6
): d 11.98, 52.21, 52.62, 53.69, 61.31,
18.15, 122.41, 135.85, 145.87 and 170.73 ppm. FT-IR max (KBr):
364.16, 3160.93, 2810.40, 1686.52, 1634.31, 1576.81, 1526.09,
2
C
1
3
1
m
6
ꢀ1
452.02, 1366.53, 1269.13 and 717.08 cm . ESI-MS: 288.6 [M
m
+
21 5
+H] . Anal. C15H N O: C, 62.7; H, 7.37; N, 24.37%. Found: C,
ꢀ1
+
6
2.64; H, 7.41; N, 24.56%.
838.94 cm . ESI-MS: 350.58 [M+H] . Anal. C20
23 5
H N O: C, 68.75;
H, 6.63; N, 20.04%. Found: C, 68.92; H, 6.77; N, 20.16.
4
.1.3.3. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-phenylpiperazin-1-yl)ac-
1
etamide (9c). H NMR (DMSO d
6
): d 2.72 (t, 4H, -(CH
, piperazine, J = 4.82 Hz), 3.35 (s, 2H,
= 7.2 Hz), 6.92 (d, 2H, ArH, J = 8.0 Hz), 7.07
m, 2H, ArH), 7.20 (m, 2H, ArH), 7.44 (m, 2H, ArH), 11.10 (br s, 1H,
NH) and 12.05 (br s, 1H, -NH) ppm. 13C NMR (DMSO d
): d 48.19,
2.42, 60.44, 115.57, 117.28, 118.80, 121.05, 128.90, 135.29,
46.04, 150.93 and 169.43 ppm. FT-IR max (KBr): 3346.45,
035.97, 2824.27, 1923.38, 1689.44, 1630.56, 1575.85, 1521.94,
2 2
) , piperazine,
4
.1.3.8. 2-(4-Benzhydrylpiperazin-1-yl)-N-(1H-benzo[d]imidazol-2-
J = 4.8 Hz), 3.18 (t, 4H, -(CH
COCH ), 6.77 (t, ArH, J
(
2
)
2
1
yl)acetamide (9h). H NMR (DMSO d
piperazine), 2.61 (s, 4H, -N(CH -, piperazine), 3.29 (s, 2H,
NHCOCH -), 4.28 (s, 1H, CH-), 7.09 (dd, 2H, ArH, J = 5.94 Hz, J
.18 Hz), 7.17 (t, 2H, ArH, J = 7.3 Hz), 7.28 (t, 4H, ArH, J = 7.6 Hz),
.43 (m, 2H, ArH), 7.45 (dd, 4H, ArH, J = 5.66 Hz, J = 3.34 Hz),
1.12 (br s, 1H, NHCOCH -) and 12.09 ppm (br s, 1H, -NH, imida-
): d 51.44, 52.61, 60.37, 75.05,
14.29, 121.03, 126.80, 127.52, 128.48, 135.75, 142.83, 145.99,
69.42 ppm. FT-IR max (KBr): 3400, 3029.67, 2950.02, 2817.70,
686.37, 1636.95, 1583.49, 1517.12, 1451.29, 1271.36, 1207.48
6 2 2
): d 2.35 (s, 4H, -N(CH ) -,
-
2
o
o
2 2
)
-
2
o
m
=
-
6
3
7
1
o
o
5
1
3
1
o
m
m
2
1
3
zole ring). C NMR (DMSO d
6
ꢀ1
449.55, 1368.03, 1224.93 and 670.73 cm
.
ESI-MS: 336.5
O: C, 68.04; H, 6.31; N, 20.88%. Found: C,
8.35; H, 6.36; N, 21.04%.
1
1
1
+
[
21 5
M+H] . Anal. C19H N
m
6
ꢀ
1
+
and 853.54, 706.17 cm
.
ESI-MS: 426.56 [M+H] . Anal.
4
.1.3.4.
N-(1H-Benzo[d]imidazol-2-yl)-2-(4-(2-fluorophenyl)piper-
C
26
H
27
N
5
O: C, 73.39; H, 6.39; N, 16.46%. Found: C, 73.11; H,
azin-1-yl)acetamide (9d). 1
H
NMR (DMSO d
, piperazine, J = 4.55 Hz), 3.12 (t, 4H, -(CH
4.50 Hz), 3.42 (s, 2H, -COCH
.50 (m, 2H, ArH), 11.40 (br s, 1H, -NH) and 12.12 (br s, 1H, -NH)
d
2.80 (t, 4H,
6
):
6
.25; N, 16.41.
-(CH
2
)
2
2
)
2
, piperazine, J
=
7
2
), 7.02 (m, ArH), 7.13 (m, 5H, ArH),
4.1.3.9. N-(1H-Benzo[d]imidazol-2-yl)-2-(4-(4-methoxyphenyl)piper-
1
3
1
ppm. C NMR (DMSO d
1
and 169.44 ppm. FT-IR
1
1
C
5
6
): d 50.07, 52.49, 60.42, 115.84, 116.91,
azin-1-yl)acetamide (9i). H NMR (DMSO d
(CH -, piperazine, J = 4.74 Hz), 3.06 (t, 4H, -N(CH
J = 4.7 Hz), 3.35 (s, 2H, -NHCOCH -), 3.68 (s, 3H, -OCH
2H, ArH), 6.88 (m, 2H, ArH), 7.09 (dd, 2H, ArH, J = 5.98 Hz, J
3.18 Hz), 7.46 (dd, 2H, ArH, J = 5.7 Hz, J = 3.3 Hz), 11.23 (br s,
1H, NHCOCH -) and 12.09 ppm (br s, 1H, -NH, imidazole ring).
C NMR (DMSO d ): d 49.60, 52.58, 55.14, 60.49, 114.21, 114.46,
17.40, 121.05, 135.45, 145.33, 146.04, 152.88, 169.45 ppm. FT-
IR max (KBr): 3351.17, 3035.84, 2949.09, 2821.60, 1685.78,
1634.41, 1578.48, 1515.35, 1369.92, 1453.74, 1239.45, 1132.20,
6
): d 2.71 (t, 4H, -N
-, piperazine,
-), 6.82 (m,
19.23, 121.04, 122.30, 124.82, 133.98, 139.80, 146.03, 154.91
2
)
2
2 2
)
m
max (KBr): 3359.68, 3040.26, 2820.56,
2
3
918.20, 1689.26, 1637.14, 1584.45, 1504.63, 1449.06, 1372.10,
o
m
=
ꢀ1
+
206.37, 1015.58 and 739.51 cm . ESI-MS: 354.5 [M+H] . Anal.
O: C, 64.58; H, 5.70; N, 19.82%. Found: C, 64.87; H,
.41; N, 19.76%.
o
m
19
H20FN
5
2
1
3
6
1
4.1.3.5. N-(1H-Benzo[d]imidazol-2-(4-(pyridin-2-yl)piperazin-1-yl)
m
1
acetamide (9e). H NMR (DMSO d
azine, J = 4.88 Hz). 3.42 (s, 2H, -COCH
azine, J = 4.95 Hz), 6.61 (m, ArH), 6.72 (d, ArH, J
H, ArH), 7.46 (m, 3H, ArH), 8.10 (m, ArH), 11.23 (br s, 1H, -NH) and
6
): d 2.71 (t, 4H, -(CH
), 3.57 (t, 4H, -(CH
= 4.6 Hz), 7.09 (m,
2
)
2
, piper-
ꢀ
1
+
2
2
)
2
, piper-
1035.44 and 823.32 cm
: C, 65.74; H, 6.34; N, 19.16%. Found: C, 65.85; H,
6.42; N, 19.37.
.
ESI-MS: 366.57 [M+H] . Anal.
o
20 23 5 2
C H N O
2