The Journal of Organic Chemistry
Article
Imidazo[1,2-a]pyridin-3-yl(4-nitrophenyl)methanone (3ag).14
127.3, 127.1, 126.6, 125.3, 125.0, 124.5, 117.8, 115.5. ESI-MS: m/z
[M + H]+ 273.
Petroleum ether/ethyl acetate = 1:1; yellow powder (yield: 134 mg,
Imidazo[1,2-a]pyridin-3-yl(naphthalen-2-yl)methanone (3ao).17
Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield: 201
1
45%); mp 184−185 °C; H NMR (400 MHz, chloroform-d) δ 9.76
(d, J = 6.8 Hz, 1H), 8.41 (d, J = 8.8 Hz, 2H), 8.19 (s, 1H), 8.03 (d, J =
8.8 Hz, 2H), 7.87 (d, J = 8.8 Hz, 1H), 7.64 (t, J = 7.2 Hz, 1H), 7.23
(d, J = 6.8 Hz, 1H). 13C{H} NMR (101 MHz, chloroform-d) δ 171.2,
146.2, 144.5, 144.3, 130.4, 130.3, 129.7, 129.0, 123.9, 118.0, 115.8,
115.5. ESI-MS: m/z [M + H]+ 268.
1
mg, 74%); mp 127−128 °C; H NMR (400 MHz, chloroform-d) δ
9.81 (d, J = 6.8 Hz, 1H), 8.40 (s, 1H), 8.31 (s, 1H), 8.01−7.93 (m,
4H), 7.86 (d, J = 8.8 Hz, 1H), 7.65−7.53 (m, 3H), 7.18 (m, 1H).
13C{H} NMR (101 MHz, chloroform-d) δ 184.8, 149.1, 145.6, 136.5,
135.1, 132.5, 130.0, 129.5, 129.3, 129.0, 128.7, 128.1, 127.9, 127.0,
125.1, 123.8, 117.8, 115.2. ESI-MS: m/z [M + H]+ 273.
Imidazo[1,2-a]pyridin-3-yl(m-tolyl)methanone (3ah).16 Petrole-
um ether/ethyl acetate = 1:1; pale brown powder (yield: 172 mg,
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73%); mp 123−124 °C; H NMR (400 MHz, chloroform-d) δ 9.75
Furan-2-yl(imidazo[1,2-a]pyridin-3-yl)methanone (3ap). Petro-
leum ether/ethyl acetate = 1:1; pale brown powder (yield: 91 mg,
(d, J = 6.0 Hz, 1H), 8.21 (s, 1H), 7.81 (d, J = 8.8 Hz, 1H), 7.69−7.66
(m, 2H), 7.55 (t, J = 6.4 Hz, 1H), 7.43 (d, J = 4.8 Hz, 2H), 7.16 (t, J
= 7.2 Hz, 1H), 2.46 (s, 3H). 13C{H} NMR (101 MHz, chloroform-d)
δ 185.1, 149.1, 145.7, 139.3, 138.5, 132.8, 129.4, 129.4, 128.9, 128.4,
126.1, 123.6, 117.8, 115.1, 21.4. ESI-MS: m/z [M + H]+ 237.
(3-Chlorophenyl)(imidazo[1,2-a]pyridin-3-yl)methanone (3ai).
Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield:
197 mg, 77%); mp 180−181 °C; 1H NMR (400 MHz, chloroform-d)
δ 9.73 (d, J = 6.8 Hz, 1H), 8.21 (s, 1H), 7.85 (s, 1H), 7.84 (d, J = 9.2
Hz, 1H), 7.75 (d, J = 7.6 Hz, 1H), 7.60−7.56 (m, 2H), 7.48 (t, J = 8.0
Hz, 1H), 7.18 (t, J = 6.8 Hz, 1H). 13C{H} NMR (101 MHz,
chloroform-d) δ 183.1, 149.4, 145.9, 140.9, 134.9, 132.0, 129.9, 129.8,
128.93, 128.9, 126.9, 123.3, 117.9, 115.4. HRMS (ESI): calcd for
C14H10ClN2O m/z [M + H]+ 257.0476; found 257.0480.
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43%); mp 149−150 °C; H NMR (400 MHz, chloroform-d) δ 9.81
(d, J = 6.8 Hz, 1H), 8.87 (s, 1H), 7.81 (d, J = 8.8 Hz, 1H), 7.71 (d, J =
0.8 Hz, 1H), 7.54 (t, J = 7.6 Hz, 1H), 7.40 (d, J = 3.2 Hz, 1H), 7.13
(t, J = 7.2 Hz, 1H), 7.63 (t, J = 2.0 Hz, 1H). 13C{H} NMR (101
MHz, chloroform-d) δ 170.5, 153. 0, 148.8, 145.9, 144.7, 129.4, 129.0,
122.5, 117.8, 117.5, 115.1, 112.4. HRMS (ESI): calcd for C12H9N2O2
m/z [M + H]+ 213.0659; found 213.0657.
Imidazo[1,2-a]pyridin-3-yl(thiophen-2-yl)methanone (3aq).16
Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield:
100 mg, 44%); mp 111−112 °C; 1H NMR (400 MHz, chloroform-d)
δ 9.65 (d, J = 7.2 Hz, 1H), 8.51 (s, 1H), 7.89 (d, J = 3.6 Hz, 1H), 7.81
(d, J = 9.2 Hz, 1H), 7.71 (d, J = 4.8 Hz, 1H), 7.54 (t, J = 7.2 Hz, 1H),
7.23 (t, J = 3.2 Hz, 1H), 7.13 (t, J = 7.2 Hz, 1H). 13C{H} NMR (101
MHz, chloroform-d) δ 175.7, 149.1, 143.8, 143.7, 132.6, 131.9, 129.3,
128.8, 128.0, 123.3, 117.9, 115.1. ESI-MS: m/z [M + H]+ 229.
1-(Imidazo[1,2-a]pyridin-3-yl)-2,2-dimethylpropan-1-one
(3aw).16 Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 125 mg, 62%); mp 137−138 °C; 1H NMR (400 MHz,
DMSO-d6) δ 9.67 (d, J = 7.2 Hz, 1H), 8.73 (s, 1H), 7.83 (d, J = 9.2
Hz, 1H), 7.63 (t, J = 7.2 Hz, 1H), 7.26 (t, J = 7.2 Hz, 1H), 1.39 (s,
9H). 13C{H} NMR (101 MHz, DMSO-d6) δ 196.7, 147.6, 143.2,
129.7, 129.1, 121.4, 117.7, 115.8, 44.1, 28.8. ESI-MS: m/z [M + H]+
203.
Imidazo[1,2-a]pyridin-3-yl(o-tolyl)methanone (3aj). Petroleum
ether/ethyl acetate = 1:1; pale brown powder (yield: 110 mg,
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47%); mp 108−109 °C; H NMR (400 MHz, chloroform-d) δ 9.82
(d, J = 6.8 Hz, 1H), 7.93 (s, 1H), 7.81 (d, J = 9.2 Hz, 1H), 7.57 (d, J =
8.8 Hz, 1H), 7.48 (d, J = 7.2 Hz, 1H), 7.42 (t, J = 6.8 Hz, 1H), 7.32
(t, J = 7.2 Hz, 2H), 7.17 (t, J = 6.8 Hz, 1H), 2.43 (s, 3H). 13C{H}
NMR (101 MHz, chloroform-d) δ 186.9, 149.3, 146.5, 139.0, 136.5,
131.2, 130.3, 129.6, 129.0, 128.3, 125.3, 124.5, 117.8, 115.3, 19.6.
HRMS (ESI): calcd for C15H13N2O m/z [M + H]+ 237.1022; found
237.1026.
Imidazo[1,2-a]pyridin-3-yl(2-methoxyphenyl)methanone (3ak).
(8-Methylimidazo[1,2-a]pyridin-3-yl)(phenyl)methanone
(3ba).14 Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 172 mg, 73%); mp 85−86 °C; 1H NMR (400 MHz,
chloroform-d) δ 9.61 (d, J = 7.2 Hz, 1H), 8.19 (s, 1H), 7.88 (d, J =
6.8 Hz, 2H), 7.62 (t, J = 7.6 Hz, 1H), 7.55 (t, J = 7.6 Hz, 2H), 7.35
(d, J = 6.8 Hz, 1H), 7.07 (t, J = 7.2 Hz, 1H), 2.71 (s, 3H). 13C{H}
NMR (101 MHz, chloroform-d) δ 184.93, 149.3, 145.0, 139.4, 132.0,
130.9, 128.9, 128.6, 128.5, 127.6, 126.7, 115.2, 17.0. ESI-MS: m/z [M
+ H]+ 237.
(8-Methoxyimidazo[1,2-a]pyridin-3-yl)(phenyl)methanone
(3ca). Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield:
181 mg, 72%); mp 98−99 °C; 1H NMR (400 MHz, chloroform-d) δ
9.34 (d, J = 6.0 Hz, 1H), 8.15 (s, 1H), 7. 88 (d, J = 6.8 Hz, 2H), 7.62
(t, J = 4.8 Hz, 1H), 7.54 (t, J = 7.6 Hz, 2H), 7.05 (t, J = 7.6 Hz, 1H),
6.85 (d, J = 6.8 Hz, 1H), 4.08 (s, 3H). 13C{H} NMR (101 MHz,
chloroform-d) δ 185.1, 148.8, 144.2, 143.0, 139.3, 130.1, 128.9, 128.6,
124.5, 121.4, 115.2, 106.1, 56.2. HRMS (ESI): calcd for C15H13N2O2
m/z [M + H]+ 253.0972; found 253.0976.
(7-Methylimidazo[1,2-a]pyridin-3-yl)(phenyl)methanone
(3ea).16 Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 175 mg, 74%); mp 130−131 °C; 1H NMR (400 MHz,
chloroform-d) δ 9.61 (d, J = 7.2 Hz, 1H), 8.15 (s, 1H), 7.86 (d, J =
7.6 Hz, 2H), 7.62−7.51 (m, 4H), 6.98 (d, J = 7.2 Hz, 1H), 2.51 (s,
3H). 13C{H} NMR (101 MHz, chloroform-d) δ 184.6, 149.6, 146.0,
141.2, 139.4, 131.9, 128.8, 128.6, 128.1, 123.3, 117.6, 116.4, 21.6. ESI-
MS: m/z [M + H]+ 237.
Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield: 100
mg, 41%); mp 110−111 °C; H NMR (400 MHz, chloroform-d) δ
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9.81 (d, J = 6.8 Hz, 1H), 7.96 (s, 1H), 7.79 (d, J = 9.2 Hz, 1H), 7.55
(t, J = 7.2 Hz, 1H), 7.51−7.44 (m, 2H), 7.16 (t, J = 6.8 Hz, 1H), 7.06
(m, 2H), 3.83 (s, 3H). 13C{H} NMR (101 MHz, chloroform-d) δ
184.3, 157.0, 146.4, 131.9, 129.4, 129.4, 129.1, 129.0, 124.6, 120.4,
117.7, 115.2, 111.6, 55.7. HRMS (ESI): calcd for C15H13N2O2 m/z
[M + H]+ 253.0972; found 253.0975.
(2-Chlorophenyl)(imidazo[1,2-a]pyridin-3-yl)methanone (3al).
Petroleum ether/ethyl acetate = 1:1; pale brown powder (yield:
140 mg, 55%); mp 154−155 °C; 1H NMR (400 MHz, chloroform-d)
δ 9.79 (d, J = 6.8 Hz, 1H), 7.92 (s, 1H), 7.82 (d, J = 8.8 Hz, 1H), 7.60
(t, J = 7.2 Hz, 1H), 7.57−7.50 (m, 2H), 7.47 (t, J = 7.6 Hz, 1H), 7.40
(t, J = 7.6 Hz, 1H), 7.20 (t, J = 6.8 Hz, 1H). 13C{H} NMR (101
MHz, chloroform-d) δ 183.0, 149.9, 146.9, 138.5, 131.5, 131.3, 130.4,
130.0, 129.2, 129.0, 126.7, 123.9, 117.9, 115.6. HRMS (ESI): calcd
for C14H10ClN2O m/z [M + H]+ 257.0476; found 257.0481.
(2-Bromophenyl)(imidazo[1,2-a]pyridin-3-yl)methanone
(3am).14 Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 150 mg, 50%); mp 165−166 °C; 1H NMR (400 MHz,
chloroform-d) δ 9.79 (d, J = 6.8 Hz, 1H), 7.89 (s, 1H), 7.82 (d, J =
9.2 Hz, 1H), 7.70 (d, J = 7.6 Hz, 1H), 7.60 (t, J = 6.8 Hz, 1H), 7.50−
7.43 (m, 2H), 7.39 (t, J = 7.6 Hz, 1H), 7.21 (t, J = 6.8 Hz, 1H).
13C{H} NMR (101 MHz, chloroform-d) δ 183.8, 149.6, 146.9, 140.4,
133.6, 131.4, 130.0, 129.2, 129.1, 127.2, 123.6, 119.9, 117.9, 115.6.
ESI-MS: m/z [M + H]+ 301.
(7-Methoxyimidazo[1,2-a]pyridin-3-yl)(phenyl)methanone
(3fa).16 Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 175 mg, 70%); mp 95−96 °C; 1H NMR (400 MHz,
chloroform-d) δ 9.56 (d, J = 7.6 Hz, 1H), 8.11 (s, 1H), 7.86 (d, J =
6.8 Hz, 2H), 7.60 (t, J = 7.2 Hz, 1H), 7.53 (t, J = 4.0 Hz, 2H),7.12 (s,
1H), 6.83 (d, J = 7.6, 1.9 Hz, 1H), 3.95 (s, 3H). 13C{H} NMR (101
MHz, chloroform-d) δ 184.3, 161.3, 145.7, 139.3, 134.1, 131.9, 130.1,
129.5, 128.7, 123.1, 109.3, 95.6, 55.9. ESI-MS: m/z [M + H]+ 253.
Imidazo[1,2-a]pyridin-3-yl(naphthalen-1-yl)methanone
(3an).19a Petroleum ether/ethyl acetate = 1:1; pale brown powder
(yield: 196 mg, 72%); mp 133−134 °C; 1H NMR (400 MHz,
chloroform-d) δ 9.92 (d, J = 5.6 Hz, 1H), 8.21 (d, J = 7.6 Hz, 1H),
8.03 (d, J = 8.4 Hz, 1H), 7.80 (s, 1H), 7.75 (d, J = 7.2 Hz, 1H), 7.73
(d, J = 8.0 Hz, 1H), 7.87 (dt, J = 8.8 Hz, 1H), 7.63−7.51 (m, 4H),
7.23 (t, J = 7.2 Hz, 1H). 13C{H} NMR (101 MHz, chloroform-d) δ
186.1, 149.3, 146.4, 136.7, 133.9, 131.3, 130.7, 129.9, 129.1, 128.5,
6243
J. Org. Chem. 2021, 86, 6239−6246