10.1002/ejoc.201900117
European Journal of Organic Chemistry
FULL PAPER
on silica gel (petroleum ether/ethyl acetate = 15/1). Yellow solid (32 mg,
86%), mp: 184-185 °C. 1H NMR (300 MHz, CDCl3) δ 12.79 (s, 1H), 8.78
(d, J = 8.2 Hz, 1H), 8.17 (d, J = 8.8 Hz, 1H), 7.95 (dd, J = 15.9, 8.5 Hz,
2H), 7.59 (t, J = 7.7 Hz, 1H), 7.22 (t, J = 7.4 Hz, 1H), 4.38 (t, J = 9.4 Hz,
2H), 3.99 (t, J = 9.4 Hz, 2H), 2.63 (s, 3H). 13C NMR (75 MHz, CDCl3) δ
164.8, 162.2, 153.4, 147.4, 138.8, 135.8, 132.8, 132.6, 129.3, 125.0,
123.7, 123.3, 120.4, 113.8, 66.4, 54.4, 16.1. HRMS (ESI-QTOF) m/z
Calcd for C17H14N4O6 [M+H]+ 371.0992, found 371.0986.
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-4-ethyl-2,6-dinitrobenzamide
(2n): Following the general procedure the title compound was
synthesized at 60 °C for 2 h. Purified by flash column chromatography on
silica gel (petroleum ether/ethyl acetate = 8/1). Yellow solid (25 mg, 65%),
mp: 207-208 °C. 1H NMR (300 MHz, CDCl3) δ 12.76 (s, 1H), 8.67 (d, J =
8.4 Hz, 1H), 8.21 (s, 2H), 7.86 (d, J = 7.9 Hz, 1H), 7.54 (t, J = 7.8 Hz, 1H),
7.16 (t, J = 7.1 Hz, 1H), 4.33 (t, J = 9.4 Hz, 2H), 3.93 (t, J = 9.6 Hz, 2H),
2.90 (q, J = 7.6 Hz, 2H), 1.38 (t, J = 7.6 Hz, 3H). 13C NMR (75 MHz,
CDCl3) δ 164.8, 159.9, 148.3, 147.6, 139.1, 132.7, 129.1, 128.6, 125.9,
123.4, 120.6, 113.7, 66.3, 54.3, 28.4, 14.4. HRMS (ESI-QTOF) m/z
Calcd for C18H16N4O6 [M+H]+ 385.1148, found 385.1145.
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-2,4-dimethyl-6-nitrobenzamide
(2i): Following the general procedure the title compound was synthesized
at 70 °C for 12 h. Purified by flash column chromatography on silica gel
(petroleum ether/ethyl acetate = 12/1). Yellow solid (27.8 mg, 82%), mp:
197-198 °C. 1H NMR (300 MHz, CDCl3) δ 12.47 (s, 1H), 8.84 (d, J = 8.3
Hz, 1H), 7.89 (d, J = 7.9 Hz, 1H), 7.83 (s, 1H), 7.55 (t, J = 7.3 Hz, 1H),
7.39 (s, 1H), 7.16 (t, J = 7.6 Hz, 1H), 4.34 (t, J = 9.6 Hz, 2H), 3.96 (t, J =
9.5 Hz, 2H), 2.48 (d, J = 6.5 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 164.5,
164.1, 145.7, 139.4, 139.0, 137.0, 136.3, 132.1, 129.9, 128.7, 122.4,
121.9, 119.8, 113.1, 65.7, 54.0, 20.5, 18.7. HRMS (ESI-QTOF) m/z
Calcd for C18H17N3O4 [M+H]+ 340.1297, found 340.1294.
4-(tert-butyl)-N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-2,6-
dinitrobenzamide (2o): Following the general procedure the title
compound was synthesized at 60 °C for 2 h. Purified by flash column
chromatography on silica gel (petroleum ether/ethyl acetate = 15/1).
Yellow solid (28.6 mg, 69%), mp: 214-215 °C. 1H NMR (300 MHz, CDCl3)
δ 12.65 (s, 1H), 8.56 (d, J = 8.3 Hz, 1H), 8.26 (s, 2H), 7.76 (d, J = 7.9 Hz,
1H), 7.43 (t, J = 7.9 Hz, 1H), 7.05 (t, J = 7.6 Hz, 1H), 4.23 (t, J = 9.5 Hz,
2H), 3.84 (t, J = 9.5 Hz, 2H), 1.34 (s, 9H). 13C NMR (75 MHz, CDCl3) δ
164.8, 159.9, 155.8, 147.6, 139.1, 132.7, 129.1, 126.4, 125.7, 123.4,
120.7, 113.8, 66.3, 54.3, 35.8, 30.7. HRMS (ESI-QTOF) m/z Calcd for
C20H20N4O6 [M+H]+ 413.1461, found 413.1458.
4-chloro-N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-2-fluoro-6-
nitrobenzamide (2j): Following the general procedure the title
compound was synthesized at 50 °C for 4 h. Purified by flash column
chromatography on silica gel (petroleum ether/ethyl acetate = 18/1).
Yellow solid (34 mg, 93%), mp: 166-167 °C. 1H NMR (300 MHz, CDCl3) δ
12.89 (s, 1H), 8.79 (d, J = 7.8 Hz, 1H), 7.99 (s, 1H), 7.91 (d, J = 6.9 Hz,
1H), 7.58–7.53 (m, 2H), 7.19 (t, J = 7.6 Hz, 1H), 4.37 (t, J = 9.1 Hz, 2H),
4.02 (d, J = 8.6 Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 164.7, 159.2 (d, JC-
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-4-fluoro-2,6-dinitrobenzamide
(2p): Following the general procedure the title compound was
synthesized at 50 °C for 1.5 h. Purified by flash column chromatography
on silica gel (petroleum ether/ethyl acetate = 12/1). Yellow solid (24 mg,
64%), mp: 205-206 °C. 1H NMR (300 MHz, CDCl3) δ 12.85 (s, 1H), 8.64
F = 254.9 Hz), 158.4, 139.0, 136.6 (d, JC-F = 10.9 Hz), 132.7, 129.2, 123.5, (d, J = 8.4 Hz, 1H), 8.13 (d, J = 7.1 Hz, 2H), 7.87 (d, J = 7.8 Hz, 1H), 7.54
122.3 (d, JC-F = 24.6 Hz), 121.1, 121.0 (d, JC-F = 3.4 Hz), 120.8, 120.3,
113.7, 66.3, 54.5. HRMS (ESI-QTOF) m/z Calcd for C16H11ClFN3O4
[M+H]+ 364.0500, found 364.0496.
(t, J = 7.7 Hz, 1H), 7.17 (t, J = 7.6 Hz, 1H), 4.33 (t, J = 9.5 Hz, 2H), 3.92
(t, J = 9.5 Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 164.8, 161.2 (d, JC-F
=
257.8 Hz), 158.6, 148.5 (d, JC-F = 8.1 Hz), 138.9, 132.8, 129.2, 124.8,
123.6, 120.5, 117.6 (d, JC-F = 25.9 Hz), 113.7, 66.4, 54.3. HRMS (ESI-
QTOF) m/z Calcd for C16H11FN4O6 [M+H]+ 375.0741, found 375.0735.
4-chloro-N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-2,6-dinitrobenzamide
(2k'): Following the general procedure the title compound was
synthesized at 50 °C for 1.5 h. Purified by flash column chromatography
on silica gel (petroleum ether/ethyl acetate = 10/1). Yellow solid (36 mg,
92%), mp: 220-221 °C. 1H NMR (300 MHz, CDCl3) δ 12.88 (s, 1H), 8.64
(d, J = 8.1 Hz, 1H), 8.38 (s, 2H), 7.88 (d, J = 7.7 Hz, 1H), 7.55 (t, J = 7.3
Hz, 1H), 7.18 (t, J = 7.7 Hz, 1H), 4.34 (t, J = 9.3 Hz, 2H), 3.94 (t, J = 9.3
Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 164.9, 158.6, 148.0, 138.8, 136.8,
132.8, 129.6, 129.2, 126.6, 123.7, 120.6, 113.7, 66.4, 54.3. HRMS (ESI-
QTOF) m/z Calcd for C16H11ClN4O6 [M+H]+ 391.0445, found 391.0437.
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-5-methyl-2-nitrobenzamide (2q-
1): Following the general procedure the title compound was synthesized
at 60 °C for 3 h. Purified by flash column chromatography on silica gel
(petroleum ether/ethyl acetate = 8/1). Yellow solid (8.5 mg, 26%), mp:
178-179 °C. 1H NMR (300 MHz, CDCl3) δ 12.69 (s, 1H), 8.81 (d, J = 8.3
Hz, 1H), 7.97 (d, J = 8.3 Hz, 1H), 7.87 (d, J = 6.5 Hz, 1H), 7.61–7.43 (m,
2H), 7.38 (d, J = 8.5 Hz, 1H), 7.14 (t, J = 7.3 Hz, 1H), 4.35 (t, J = 9.4 Hz,
2H), 3.99 (t, J = 9.5 Hz, 2H), 2.49 (s, 3H). 13C NMR (75 MHz, CDCl3) δ
164.8, 145.0, 144.8, 139.5, 133.4, 132.7, 131.0, 129.6, 129.2, 124.7,
123.0, 120.1, 113.6, 66.3, 54.4, 21.5. HRMS (ESI-QTOF) m/z Calcd for
C17H15N3O4 [M+H]+ 326.1141, found 326.1138.
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-4-methyl-2,6-dinitrobenzamide
(2m): Following the general procedure the title compound was
synthesized at 60 °C for 1.5 h. Purified by flash column chromatography
on silica gel (petroleum ether/ethyl acetate = 5/1). Yellow solid (24.8 mg,
67%), mp: 232-233 °C. 1H NMR (300 MHz, CDCl3) δ 12.67 (s, 1H), 8.57
(d, J = 8.1 Hz, 1H), 8.09 (s, 2H), 7.76 (d, J = 7.9 Hz, 1H), 7.43 (t, J = 8.0
Hz, 1H), 7.05 (t, J = 7.6 Hz, 1H), 4.22 (t, J = 9.5 Hz, 2H), 3.82 (t, J = 9.5
Hz, 2H), 2.51 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 164.8, 159.8, 147.5,
142.3, 139.1, 132.7, 129.7, 129.1, 125.8, 123.4, 120.6, 113.7, 66.3, 54.3,
21.2. HRMS (ESI-QTOF) m/z Calcd for C17H14N4O6 [M+H]+ 371.0992,
found 371.0989.
N-(2-(4,5-dihydrooxazol-2-yl)phenyl)-3-methyl-2,6-dinitrobenzamide
(2q-2): Following the general procedure the title compound was
synthesized at 60 °C for 3 h. Purified by flash column chromatography on
silica gel (petroleum ether/ethyl acetate = 5/1). Yellow solid (11.7 mg,
32%), mp: 196-197 °C. 1H NMR (300 MHz, CDCl3) δ 12.94 (s, 1H), 8.65
(d, J = 8.4 Hz, 1H), 8.17 (d, J = 8.4 Hz, 1H), 7.85 (d, J = 7.4 Hz, 1H),
7.62–7.43 (m, 2H), 7.16 (t, J = 7.4 Hz, 1H), 4.35 (t, J = 9.5 Hz, 2H), 3.97
(t, J = 9.5 Hz, 2H), 2.51 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 164.7,
159.4, 149.4, 145.0, 138.9, 137.6, 133.1, 132.7, 129.1, 127.3, 126.4,
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