1554
J. Zhao et al.
SPECIAL TOPIC
ganic layer was dried (Na2SO4), and concentrated under vacuum.
The crude product was purified by column chromatography to give
the product 2.
7.97 (d, J = 8.0 Hz, 1 H), 7.85 (d, J = 8.8 Hz, 1 H), 7.39 (t, J = 8.0
Hz, 1 H), 3.92 (s, 3 H), 2.18 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 168.9, 166.1, 157.8, 147.6,
128.9, 125.0, 124.3, 123.8, 123.7, 123.1, 121.6, 117.1, 112.0, 52.3,
23.5.
HRMS (ESI): m/z [M + H]+ calcd for C16H14NO4: 284.0917; found:
284.0942.
6-Acetamido-2-nitrodibenzofuran (2a)
White solid; yield: 54 mg (99%); mp 226.2–227.9 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.30 (br, 1 H), 9.20 (s, 1 H),
8.43 (d, J = 8.6 Hz, 1 H), 8.13 (d, J = 7.6 Hz, 1 H), 7.95–8.01 (m, 2
H), 7.44 (t, J = 7.8 Hz, 1 H), 2.18 (s, 3 H).
6-(tert-Butoxycarbonylamido)-2-nitrodibenzofuran (2g)
White solid; yield: 40 mg (61%); mp 187.2–189.3 °C.
13C NMR (125 MHz, DMSO-d6): δ = 168.9, 158.2, 148.2, 143.7,
124.8, 124.2, 124.0, 123.3, 123.3, 122.2, 118.0, 117.6, 112.5, 23.5.
HRMS (ESI): m/z [M + H]+ calcd for C14H11N2O4: 271.0713; found:
271.0728.
1H NMR (400 MHz, CDCl3): δ = 8.82 (s, 1 H), 8.38 (d, J = 8.8 Hz,
1 H), 8.18–8.22 (m, 1 H), 7.62–7.64 (m, 2 H), 7.36–7.40 (m, 1 H),
7.07 (s, 1 H), 1.58 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 158.5, 152.3, 146.5, 144.0, 125.4,
124.7, 124.6, 123.0, 122.9, 118.0, 117.4, 114.8, 111.9, 81.4, 28.3.
HRMS (ESI): m/z [M + Na]+ calcd for C17H16N2NaO5: 351.0951;
found: 351.0951.
6-Acetamido-2-fluorodibenzofuran (2b)
White solid; yield: 28 mg (56%); mp 158.8–161.3 °C.
1H NMR (400 MHz, CDCl3): δ = 8.35 (d, J = 6.8 Hz, 1 H), 7.74 (s,
1 H), 7.59–7.62 (m, 2 H), 7.49 (d, J = 4.4 Hz, 1 H), 7.17–7.33 (m, 2
H), 2.32 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 168.4, 160.2, 158.3, 151.7, 146.5,
125.5, 125.4, 124.0, 124.0, 123.8, 123.6, 118.7, 115.9, 114.7, 114.5,
112.3, 112.2, 107.1, 106.9, 24.7.
6-(Benzoylamido)-2-nitrodibenzofuran (2h)
White solid; yield: 54 mg (80%); mp 277.4–280.3 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.63 (s, 1 H), 9.24 (d, J = 2.4
Hz, 1 H), 8.43 (dd, J = 9.2, 2.4 Hz, 1 H), 8.29 (dd, J = 7.8, 1.0 Hz,
1 H), 8.07–8.09 (m, 2 H), 7.98 (d, J = 9.0 Hz, 1 H), 7.75 (d, J = 7.2
Hz, 1 H), 7.64–7.67 (m, 1 H), 7.51–7.60 (m, 3 H).
HRMS (ESI): m/z [M + H]+ calcd for C14H11FNO2: 244.0768;
found: 244.0721.
13C NMR (125 MHz, DMSO-d6): δ = 165.5, 158.4, 150.6, 143.7,
133.8, 132.0, 128.5, 127.9, 125.3, 124.7, 124.2, 123.7, 123.5, 123.4,
119.3, 118.0, 112.6.
HRMS (ESI): m/z [M + H]+ calcd for C19H13N2O4: 333.0870; found:
333.0867.
6-Acetamido-2-chlorodibenzofuran (2c)
White solid; yield: 23 mg (44%); mp 224.0–226.1 °C.
1H NMR (400 MHz, CDCl3): δ = 8.37 (d, J = 8.0 Hz, 1 H), 7.91 (d,
J = 2.0 Hz, 1 H), 7.70 (br, 1 H), 7.63 (d, J = 7.6 Hz, 1 H), 7.50 (d,
J = 8.8 Hz, 1 H), 7.42 (dd, J = 8.8, 2.0 Hz, 1 H), 7.34 (t, J = 8.0 Hz,
1 H), 2.33 (s, 3 H).
N-(8-Nitrodibenzofuranyl-4-yl)pyrrolidin-2-one (2i)
White solid; yield: 45 mg (75%); mp 181.2–182.5 °C.
13C NMR (125 MHz, CDCl3): δ = 168.4, 154.0, 146.1, 128.8, 127.3,
125.9, 123.8, 123.8, 123.4, 120.8, 118.8, 115.9, 112.6, 24.7.
HRMS (ESI): m/z [M + H]+ calcd for C14H11ClNO2: 260.0473;
found: 260.0487.
1H NMR (400 MHz, DMSO-d6): δ = 9.23 (d, J = 2.4 Hz, 1 H), 8.43
(dd, J = 9.2, 2.4 Hz, 1 H), 8.30 (d, J = 7.6 Hz, 1 H), 7.98 (d, J = 9.2
Hz, 1 H), 7.72 (d, J = 8.0 Hz, 1 H), 7.52 (t, J = 7.6 Hz, 1 H), 4.04 (t,
J = 7.0 Hz, 2 H), 2.55 (t, J = 8.0 Hz, 2 H), 2.18–2.25 (m, 2 H).
13C NMR (125 MHz, DMSO-d6): δ = 173.8, 158.3, 150.2, 143.8,
125.0, 124.4, 124.3, 124.2, 124.2, 123.5, 119.9, 118.0, 112.7, 49.2,
30.7, 18.5.
6-Acetamido-2-cyanodibenzofuran (2d)
White solid; yield: 41 mg (81%); mp 236.5–239.9 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.28 (s, 1 H), 8.79 (s, 1 H),
7.93–8.02 (m, 4 H), 7.43 (t, J = 8.0 Hz, 1 H), 2.18 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 168.8, 157.0, 147.5, 131.5,
126.6, 124.9, 124.1, 123.9, 122.9, 122.0, 119.1, 117.2, 113.2, 106.1,
23.5.
HRMS (ESI): m/z [M + H]+ calcd for C15H11N2O2: 251.0815; found:
251.0837.
HRMS (ESI): m/z [M + H]+ calcd for C16H13N2O4: 297.0870; found:
297.0899.
4-Acetamidodibenzofuran (2j)
White solid; yield: 32 mg (69%); mp 186.5–187.8 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.21 (s, 1 H), 8.15 (d, J = 7.6
Hz, 1 H), 7.94 (d, J = 8.0 Hz, 1 H), 7.88 (d, J = 7.6 Hz, 1 H), 7.73
(d, J = 8.2 Hz, 1 H), 7.55 (t, J = 7.6 Hz, 1 H), 7.43 (t, J = 7.6 Hz, 1
H), 7.34 (t, J = 7.8 Hz, 1 H), 2.17 (s, 3 H).
13C NMR (100 MHz, DMSO-d6): δ = 169.3, 155.6, 147.4, 128.1,
124.7, 124.3, 124.3, 123.7, 123.6, 121.7, 121.3, 116.9, 112.1, 24.0.
HRMS (ESI): m/z [M + H]+ calcd for C14H12NO2: 226.0863; found:
226.0865.
6-Acetamido-2-formyldibenzofuran (2e)
White solid; yield: 39 mg (76%); mp 228.3–231.4 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.26 (br, 1 H), 10.14 (s, 1 H),
8.77 (s, 1 H), 8.11 (dd, J = 8.4, 1.6 Hz, 1 H), 7.93–8.04 (m, 3 H),
7.42 (t, J = 8.0 Hz, 1 H), 2.18 (s, 3 H).
13C NMR (125 MHz, DMSO-d6): δ = 192.1, 168.8, 158.5, 147.6,
132.2, 129.3, 124.7, 124.0, 123.9, 123.7, 123.6, 121.7, 117.0, 112.5,
23.5.
HRMS (ESI): m/z [M + H]+ calcd for C15H12NO3: 254.0812; found:
Acknowledgment
254.0835.
We are grateful for the financial support by National Science Foun-
dation of China (21072190).
Methyl 6-Acetamidodibenzofuran-2-carboxylate (2f)
White solid; yield: 51 mg (89%); mp 241.0–241.9 °C.
1H NMR (400 MHz, DMSO-d6): δ = 10.24 (s, 1 H), 8.81 (d, J = 1.4
Hz, 1 H), 8.15 (dd, J = 8.8, 1.6 Hz, 1 H), 8.05 (d, J = 7.6 Hz, 1 H),
Supporting Information for this article is available online at
Synthesis 2012, 44, 1551–1555
© Georg Thieme Verlag Stuttgart · New York