March 2011
Microwave-Assisted Expeditious Synthesis of Novel
Benzo[b][1,8]-naphthyridine-3-carbonitriles
401
AlCl3 (1.5 mmol), and dry DCM (2 mL) were mixed in a
sealed pressure regulation 10-mL pressurized vial with ‘‘snap-
on’’ cap. The mixture was irradiated in a single-mode MW
synthesis system at 120 W power and 50ꢀC temperature for 7–
10 min. After completion of reaction (TLC), the mixture was
poured into a beaker containing ice cold water and was
extracted with DCM (3ꢁ 10 mL). The organic phase was dried
over anhydrous Na2SO4, filtered and the solvent was evapo-
rated. The resultant solid was recrystallized from ethanol to
yield pure product 3a–j.
1522 cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.56–7.70 (m,
3H, ArH), 7.54 (s, 1H, ArH), 7.36–7.47 (m, 5H, ArH), 4.39 (s,
2H, NH2), 2.96 (t, J ¼ 5.7 Hz, 2H, CH2), 2.33 (t, J ¼ 5.7 Hz,
2H, CH2), 1.84–1.86 (m, 4H, 2ꢁ CH2); 13C-NMR (75 MHz,
CDCl3): d ¼ 164.8, 161.3, 154.8, 152.4, 149.2, 137.9, 135.9,
135.3, 131.1, 130.6, 129.5, 128.2, 127.8, 126.2, 114.9, 112.4,
105.8, 104.3, 34.3, 23.5, 22.3, 22.2; Anal. Calcd. for
C25H19ClN4S: C, 67.79; H, 4.32; N, 12.65; Found: C, 67.91;
H, 4.24; N, 12.69.
5-Amino-4-(4-bromophenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3f). Brown
solid; IR (KBr): 3468, 3348, 3216, 2988, 2215, 1628, 1536,
5-Amino-4-phenyl-2-phenylsulfanyl-6,7,8,9-tetrahydrobenzo-
[b][1,8]-naphthyridine-3-carbonitrile (3a). Yellow solid; IR
(KBr): 3432, 3350, 2928, 2210, 1617, 1531 cmꢂ1
;
1H-NMR
1501 cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.68–7.77 (m,
(300 MHz, CDCl3): d ¼ 7.45–7.71 (m, 10H, ArH), 4.39 (s,
2H, NH2), 2.97 (t, J ¼ 5.4 Hz, 2H, CH2), 2.30 (t, J ¼ 5.4 Hz,
2H, CH2), 1.84–1.86 (m, 4H, 2ꢁ CH2); 13C-NMR (75 MHz,
CDCl3): d ¼ 164.3, 161.4, 154.7, 154.3, 149.6, 136.1, 135.6,
130.4, 129.8, 129.5, 127.9, 115.0, 112.1, 105.9, 104.3, 34.0,
23.4, 22.2, 18.4; Anal. Calcd. for C25H20N4S: C, 73.50; H,
4.93; N, 13.71; Found: C, 73.41; H, 4.98; N, 13.75.
4H, ArH), 7.32–7.47 (m, 5H, ArH), 4.38 (s, 2H, NH2), 2.95 (m,
2H, CH2), 2.57 (m, 2H, CH2), 2.30–2.32 (m, 4H, 2ꢁ CH2);
13C-NMR (75 MHz, CDCl3): d ¼ 163.5, 158.7, 155.2, 152.2,
148.7, 135.5, 134.8, 132.7, 129.6, 128.5, 115.1, 112.8, 104.9,
34.8, 33.7, 22.7, 22.1; Anal. Calcd. for C25H19BrN4S: C, 61.60;
H, 3.93; N, 11.49; Found: C, 61.68; H, 3.98; N, 11.45.
5-Amino-4-(3-bromophenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3g). Light
yellow solid; IR (KBr): 3438, 3336, 2218, 1623, 1547, 1488
5-Amino-4-(4-methylphenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3b). Yellow
solid; IR (KBr): 3467, 3346, 2921, 2217, 1621, 1539, 1510
cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.67–7.76 (m, 3H,
cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.69–7.72 (m, 2H,
ArH), 7.59 (s, 1H, ArH), 7.41–7.52 (m, 5H, ArH), 4.41 (s, 2H,
NH2), 2.94 (t, J ¼ 5.4 Hz, 2H, CH2), 2.31 (t, J ¼ 5.4 Hz, 2H,
CH2), 1.84-1.86 (m, 4H, 2ꢁ CH2); 13C-NMR (75 MHz,
CDCl3): d ¼ 164.8, 161.4, 154.8, 152.3, 149.2, 138.1, 133.6,
131.3, 129.5, 127.8, 126.6, 123.9, 114.8, 112.4, 105.8, 34.2,
33.5, 23.5, 22.2; Anal. Calcd. for C25H19BrN4S: C, 61.60; H,
3.93; N, 11.49; Found: C, 61.47; H, 3.85; N, 11.55.
ArH), 7.40–7.47 (m, 5H, ArH), 7.31–7.34 (m, 2H, ArH), 4.45
(s, 2H, NH2), 2.95 (t, J ¼ 5.7 Hz, 2H, CH2), 2.48 (s, 3H, CH3),
2.30 (t, J ¼ 5.7 Hz, 2H, CH2), 1.83–1.85 (m, 4H, 2ꢁ CH2);
13C-NMR (75 MHz, CDCl3): d ¼ 164.3 (C), 161.2 (C), 154.9
(C), 154.6 (C), 149.6 (C), 140.6 (C), 135.4 (CH), 133.1 (C),
130.5 (CH), 129.4 (CH), 128.1 (C), 127.8 (CH), 115.2 (C),
112.0 (C), 106.3 (C), 104.6 (C), 34.2 (CH2), 23.4 (CH2), 22.4
(CH2), 22.2 (CH2), 21.5 (CH3); Anal. Calcd. for C26H22N4S: C,
73.90; H, 5.25; N, 13.26; Found: C, 74.01; H, 5.16; N, 13.32.
5-Amino-4-(4-nitrophenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3h). Yellow
solid; IR (KBr): 3426, 3318, 3076, 2222, 1637, 1541, 1518
5-Amino-4-(4-methoxyphenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3c). Light
yellow solid; IR (KBr): 3478, 3339, 2920, 2218, 1630, 1548,
cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 8.41–8.50 (m, 4H,
ArH), 7.46–7.57 (m, 5H, ArH), 5.55 (s, 2H, NH2), 2.98 (m,
2H, CH2), 2.32 (m, 2H, CH2), 1.86 (m, 4H, 2ꢁ CH2); 13C-
NMR (75 MHz, CDCl3): d ¼ 162.3, 161.1, 154.5, 152.6,
148.7, 135.8, 135.5, 129.8, 129.6, 129.3, 124.9, 124.4, 112.2,
105.7, 104.7, 33.8, 22.6, 22.4, 18.5; Anal. Calcd. for
C25H19N5O2S: C, 66.21; H, 4.22; N, 15.44; Found: C, 66.29;
H, 4.15; N, 15.49.
1507 cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.69–7.71 (m,
2H, ArH), 7.45–7.47 (m, 3H, ArH), 7.36 (d, J ¼ 8.4 Hz, 2H,
ArH), 7.11 (d, J ¼ 8.4 Hz, 2H, ArH), 4.49 (s, 2H, NH2), 3.91
(s, 3H, OCH3), 2.95 (t, J ¼ 5.4 Hz, 2H, CH2), 2.31 (t, J ¼ 5.4
Hz, 2H, CH2), 1.84–1.86 (m, 4H, 2ꢁ CH2); 13C-NMR (75
MHz, CDCl3): d ¼ 164.1 (C), 161.5 (C), 154.6 (C), 154.3 (C),
148.7 (C), 140.3 (C), 135.2 (CH), 133.2 (C), 130.7 (CH),
129.3 (CH), 128.3 (C), 127.5 (CH), 115.1 (C), 112.0 (C),
109.5 (C), 106.4 (C), 55.1 (CH3), 34.0 (CH2), 24.1 (CH2), 23.5
(CH2), 22.1 (CH2); Anal. Calcd. for C26H22N4OS: C, 71.21; H,
5.06; N, 12.78; Found: C, 71.32; H, 5.13; N, 12.71.
5-Amino-2-(4-methoxyphenylsulfanyl)-4-phenyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3i). Yellow
solid; IR (KBr): 3434, 3330, 3048, 2209, 1628, 1551, 1437
cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.44–7.62 (m, 5H,
ArH), 6.95–7.01 (m, 4H, ArH), 4.38 (s, 2H, NH2), 3.86 (s, 3H,
OCH3), 2.95 (t, J ¼ 5.7 Hz, 2H, CH2), 2.29 (t, J ¼ 5.7 Hz,
2H, CH2), 1.83–1.85 (m, 4H, 2ꢁ CH2); 13C-NMR (75 MHz,
CDCl3): d ¼ 163.7 (C), 158.9 (C), 155.1 (C), 154.6 (C), 148.4
(C), 141.0 (C), 136.3 (CH), 133.5 (C), 130.2 (CH), 129.6
(CH), 127.9 (C), 126.7 (CH), 115.6 (C), 111.9 (C), 109.7 (C),
105.1 (C), 55.4 (CH3), 34.1 (CH2), 23.9 (CH2), 23.3 (CH2),
22.3 (CH2); Anal. Calcd. for C26H22N4OS: C, 71.21; H, 5.06;
N, 12.78; Found: C, 71.10; H, 4.98; N, 12.84.
5-Amino-4-(4-chlorophenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3d). Yellow
solid; IR (KBr): 3470, 3343, 2951, 2221, 1628, 1544, 1492
cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.59–7.71 (m, 4H,
ArH), 7.39–7.48 (m, 5H, ArH), 4.34 (s, 2H, NH2), 2.96 (t, J ¼
5.7 Hz, 2H, CH2), 2.32 (t, J ¼ 5.7 Hz, 2H, CH2), 1.86 (m, 4H,
2ꢁ CH2); 13C-NMR (75 MHz, CDCl3): d ¼ 163.7, 159.9,
154.1, 152.6, 149.2, 135.8, 134.6, 133.9, 129.4, 129.0, 128.8,
114.4, 112.0, 105.4, 38.6, 33.6, 22.9, 21.6; Anal. Calcd. for
C25H19ClN4S: C, 67.79; H, 4.32; N, 12.65; Found: C, 67.66;
H, 4.39; N, 12.60.
5-Amino-2-(4-methylphenylsulfanyl)-4-phenyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3j). Orange
solid; IR (KBr): 3450, 3326, 3047, 2921, 2214, 1617, 1547,
1463 cmꢂ1
;
1H-NMR (300 MHz, CDCl3): d ¼ 7.56–7.61 (m,
5-Amino-4-(3-chlorophenyl)-2-phenylsulfanyl-6,7,8,9-tetra-
hydrobenzo[b][1,8]-naphthyridine-3-carbonitrile (3e). Light
yellow solid; IR (KBr): 3438, 3341, 3036, 2219, 1628, 1547,
5H, ArH), 7.26–7.44 (m, 4H, ArH), 4.40 (s, 2H, NH2), 2.93
(m, 2H, CH2), 2.42 (s, 3H, CH3), 2.29 (m, 2H, CH2), 1.84 (m,
4H, 2ꢁ CH2); 13C-NMR (75 MHz, CDCl3): d ¼ 164.1 (C),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet