Synthesis of Imidazo[4,5-b]pyridine Analogues
K
yellow solid (55 mg, 79 %). Mp 145.6–146.38C. dH (300 MHz,
CDCl3) 1.65–1.73 (m, 2 H), 1.89–2.05 (m, 4 H), 2.60–2.62
(m, 2H), 4.04 (s, 3 H), 4.07 (s, 3 H), 4.39–4.42 (m, 1 H), 7.21–
7.25 (m, 1 H), 8.38–8.43 (m, 2H), 8.52 (s, 1H). dC (75 MHz,
CDCl3) 23.77, 24.68, 29.61, 30.35, 32.59, 54.29, 55.27, 58.42,
118, 127.16, 143.58, 144.13, 160.41, 166.24, 168.76. m/z 326.14
(M þ H). Anal. Calc. for C17H19N5O2: C 62.75, H 5.89, N 21.52.
Found: C 62.71, H 5.92, N 21.55 %.
118.39, 126.89, 127.80, 129.13, 131.91, 135.41, 143.48, 148.33,
148.93. m/z 270.2 (M þ H). Anal. Calc. for C15H15N3S: C 66.88,
H 5.61, N 15.60. Found: C 66.97, H 5.57, N 15.57 %.
3-Cyclopentyl-2-(pyridin-3-yl)-3H-imidazo[4,5-b]
pyridine (5l)
Prepared from 4l using the general procedure (Method B).
Purification by flash column chromatography (48–52 % ethyl
acetate in light petroleum) yielded the product as a white
solid (50 mg, 70 %). Mp 134.2–135.58C. dH (400 MHz, CDCl3)
1.70–1.74 (m, 2H), 2.06–2.21 (m, 4H), 2.68–2.75 (m, 2H), 4.80–
4.85 (m, 1H), 7.28–7.31 (q, J 5.5, 1H), 7.53–7.57 (dd, J1 2.5, J2
4.8, 1H), 8.11–8.15 (t, J 7.0, 2H), 8.44–8.45 (d, J 4.6, 1H), 8.82
(s,1H), 8.98 (s, 1H). dC (100 MHz, CDCl3) 24.82, 30.74, 58.28,
118.45, 123.67, 127.37, 135.65, 137.09, 143.85, 148.16, 149.84,
150.93, 151.98. m/z 265.2 (M þ H). Anal. Calc. for C16H16N4:
C 72.70, H 6.10, N 21.20. Found: C 72.77, H 6.08, N 21.14 %.
3-Cyclopentyl-2-(2-methoxypyrimidin-5-yl)-3H-
imidazo[4,5-b]pyridine (5h)
Prepared from 4h using the general procedure (Method B).
Purification by flash column chromatography (38–42 % ethyl
acetate in light petroleum) yielded product as a white solid
(40 mg, 69 %). Mp 139.2–140.38C. dH (400 MHz, CDCl3) 1.55–
1.72 (m, 2H), 1.80–2.22 (m, 4H), 2.60–2.72 (m, 2H), 4.10(s, 3 H),
4.68–4.72 (m, 1H), 7.21–7.26 (m, 1H), 8.02–8.04 (m, 1H), 8.36–
8.38 (m, 1H), 8.85 (s, 2H). dC (100MHz, CDCl3) 23.80, 30.78,
55.48, 58.36, 118.49, 127.32, 135.65, 143.86, 148.09, 159.59,
165.94. m/z 296.14 (M þ H). Anal. Calc. for C16H17N5O: C
65.07, H 5.80, N 23.71. Found: C 65.27, H 5.98, N 23.74 %.
3-Cyclopentyl-2-vinyl-3H-imidazo[4,5-b]pyridine (5m)
Prepared from 4m using the general procedure (Method B
and Method A). Purification by flash column chromatography
(31–36 % ethyl acetate in light petroleum) yielded the product as
a white solid (11 mg, 62 %). Mp 115.6–116.38C. dH (400 MHz,
CDCl3) 1.80–1.90 (m, 2H), 2.06–2.10 (m, 4H), 2.13–2.18 (m,
2H), 5.11–5.20 (m, 1H), 5.80–5.82 (d, 1H), 6.67–6.71 (m, 1H),
6.90–7.01 (m, 1H), 7.22–7.29 (m, 1H), 8.03–8.04 (d, 1H), 8.35–
8.36 (d, 1H). dC (100 MHz, CDCl3) 24.83, 30.59, 58.07, 118.64,
119.22, 120.01, 128.13, 129.06, 137.24, 144.24, 146.32. m/z
214.14 (M þ H). Anal. Calc. for C13H15N3: C 73.21, H 7.09,
N 19.70. Found: C 73.27, H 6.98, N 19.79 %.
3-Cyclopentyl-2-(pyridin-2-yl)-3H-imidazo[4,5-b]
pyridine (5i)
Prepared from 4i using the general procedure (Method B).
Purification by flash column chromatography (48–52 % ethyl
acetate in light petroleum) yielded the product as a white solid
(10 mg, 15 %). Mp 124.6–125.38C. dH (400 MHz, CDCl3) 1.72–
1.75 (m, 2H), 2.03–2.06 (m, 2H), 2.16–2.19 (m, 2H), 2.40–2.44
(m, 2H), 5.11–5.20 (m, 1H), 7.15–7.18(q, J 5.0, 1H) 7.25–7.27
(dd, J1 1.0, J2 5.0, 1H), 7.35–7.37 (d, J 8.2, 1H), 7.84–7.91 (m,
2H), 8.27–8.29 (dd, J1 1.4, J2 4.9, 1H), 8.40–8.41 (t, J 3.3, 1H).
dC (100 MHz, CDCl3) 24.72, 30.60, 54.67, 113.82, 118.0,
121.57, 125.80, 132.71, 140.19, 141.97, 146.55, 148.52,
154.94, 160.15. m/z 265.2 (M þ H). Anal. Calc. for C16H16N4:
C 72.70, H 6.10, N 21.20. Found: C 72.84, H 6.04, N 21.13 %.
3-Cyclopentyl-2-cyclopropyl-3H-imidazo[4,5-b]
pyridine (5n)
Prepared from 4n using the general procedure (Method B
and Method A). Purification by flash column chromatography
(31–36 % ethyl acetate in light petroleum) yielded the product
as a white solid (14 mg, 40 %). Mp 114.6–115.68C. dH
(400 MHz, CDCl3) 1.22–1.27 (m, 4H), 1.71–1.75 (m, 2H),
2.04–2.08 (m, 4H), 2.09–2.11 (m, 4H), 5.21–5.25 (m, 1H),
7.19–7.22 (m, 1H), 7.88–7.90 (d, 1H), 8.25–8.26 (d, 1H). dC
(100 MHz, CDCl3) 2.82, 9.13, 24.81, 30.55, 58.07, 120.14,
128.08, 129.42, 144.48, 145.33, 150.54. m/z 228.14 (M þ H).
Anal. Calc. for C14H17N3: C 73.98, H 7.54, N 18.49. Found:
C 73.77, H 7.78, N 18.64 %.
3-Cyclopentyl-2-(furan-2-yl)-3H-imidazo[4,5-b]
pyridine (5j)
Prepared from 4j using the general procedure (Method B and
Method A). Purification by flash column chromatography (40–
45 % ethyl acetate in light petroleum) yielded the product as a
pale-yellow solid (50 mg, 77 %). Mp 147.4–148.58C. dH
(400 MHz, CDCl3) 1.67–1.71 (m, 2H), 2.01–2.14 (m, 4H),
2.61–2.69 (m, 2H), 5.07–5.13 (m, 1H), 7.13–7.17 (m, 2H),
7.55–7.56 (d, J 4.84, 2H), 8.01–8.04 (dd, J1 1.88, J2 8.24, 1H),
8.32–8.33 (dd, J1 1.24, J2 4.92, 1H). dC (100 MHz, CDCl3)
24.89, 30.60, 58.06, 118.42, 126.91, 127.81, 129.14, 131.94,
135.46, 143.76, 148.36, 149.08. m/z 254.2 (M þ H). Anal. Calc.
for C15H15N3O: C 71.13, H 5.97, N 16.59. Found: C 71.22,
H 5.91, N 16.53 %.
1-Methyl-2-phenyl-1H-imidazo[4,5-b]pyridine (5q*)
Prepared from 4b using the general procedure (Method C).
Purification by flash column chromatography (40–45 % ethyl
acetate in light petroleum) yielded 90 % product as a light-
yellow solid (35 mg). Mp 123.8–124.88C. dH (400 MHz, CDCl3)
4.24 (s, 3H), 7.56–7.78 (m, 6H), 7.98 (d, J 8.24, 1H), 8.86 (d, J
8.64, 1H). dC (100 MHz, CDCl3) 29.76, 120.54, 126.11, 126.83,
127.78, 129.27, 130.12, 132.44, 146.34, 150.54, 151.88. m/z
210.2 (M þ H). Anal. Calc. for C13H11N3: C 74.62, H 5.30,
N 20.08. Found: C 74.68, H 5.27, N 20.04 %.
3-Cyclopentyl-2-(thiophen-2-yl)-3H-imidazo[4,5-b]
pyridine (5k)
Prepared from 4k using the general procedure (Method B
and Method A). Purification by flash column chromatography
(31–36 % ethyl acetate in light petroleum) yielded the product as
a yellow solid (55 mg, 80 %). Mp 144.2–145.38C. dH (400 MHz,
CDCl3) 1.74–1.78 (m, 2H), 2.07–2.23 (m, 4H), 2.69–2.78
(m, 2H), 5.18–5.22 (m, 1H), 7.24–7.27(m, 2H) 7.62–7.63 (d,
J 4.6, 2H), 8.08–8.10 (dd, J1 1.3, J2 8.0, 1H), 8.39–8.40 (dd, J1
1.5, J2 4.8, 1H). dC (100 MHz, CDCl3) 24.88, 30.58, 58.05,
3-(3,4-Dimethoxybenzyl)-2-phenyl-3H-imidazo[4,5-b]
pyridine (5r)
Prepared from 4b using the general procedure (Method C).
Purification by flash column chromatography (55–60 % ethyl