SYNTHESIS OF 2-AMINOBENZOXAZOLES
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N-(4-Nitrophenyl)benzoxazol-2-amine (3e). Yield: 77%, yellow solid; mp
1
168–170 ꢀC; H NMR [400 MHz, (CD3)2SO] d 7.10–7.22 (m, 3H), 7.25–7.36 (m,
2H), 7.60–7.63 (m, 1H), 8.07 (d, J ¼ 9.2 Hz, 1H), 8.35 (d, J ¼ 9.2 Hz, 1H), 11.75 (s,
1H, NH); 13C NMR [100 MHz, (CD3)2SO]: d 109.92, 110.23, 117.72, 122.27,
124.22, 125.78, 130.76, 141.72, 143.75, 154.83, 157.35; MS (m=z): 256.60 (Mþ1).
C13H9N3O3 calcd. C, 61.18; H, 3.55; N, 16.46. Found: C, 61.21; H, 3.57; N, 16.49.
N-(3-Chloro-4-fluorophenyl)benzoxazol-2-amine (3f). Yield: 82%, white
solid; mp 201–203 ꢀC; 1H NMR [400 MHz, (CD3)2SO] d 7.14–7.16 (m, 1H),
7.21–7.23 (m, 1H), 7.43 (t, J ¼ 9.0 Hz, 1H), 7.48–7.51 (m, 2H), 7.60–7.64 (m, 1H),
8.06–8.08 (m, 1H), 10.85 (s, 1H, NH);13C NMR [100 MHz, (CD3)2SO]: d 109.57,
117.33, 117.57, 117.79, 118.24, 119.04, 119.82, 120.00, 122.49, 124.61, 142.44,
147.42, 158.01; MS (m=z): 263.27 (Mþ1). C13H8ClFN2O calcd. C, 59.44; H, 3.07;
N, 10.66. Found: C, 59.47; H, 3.09; N, 10.69.
N-(4-Chloro-3-trifluoromethylphenyl)benzoxazol-2-amine (3g). Yield:
1
79%, white solid; mp 199–200 ꢀC; H NMR [400 MHz, (CD3)2SO] d 7.15–7.19 (m,
1H), 7.23–7.27 (m, 1H), 7.49–7.53 (m, 2H), 7.72 (d, 1H), 8.03–8.06 (m, 1H),
8.27–8.28 (m, 1H), 11.11 (s, 1H, NH); 13C NMR [100 MHz, (CD3)2SO]: d 109.71,
116.59, 116.65, 117.52, 122.70, 122.77, 123.02, 124.71, 127.57, 132.80, 138.74,
142.27, 147.41, 157.70; MS (m=z): 313.27 (Mþ1). C14H8ClF3N2O calcd. C, 53.78;
H, 2.58; N, 8.96. Found: C, 53.80; H, 2.61; N, 8.99.
N-(4-Methylphenyl)benzoxazol-2-amine (3 h). Yield: 74%, white solid; mp
180–181 ꢀC; 1H NMR [400 MHz, (CD3)2SO] d 2.26 (s, 3H), 7.10–7.12 (m, 1H),
7.15–7.17 (m, 2H), 7.19–7.21 (m, 1H), 7.41–7.46 (m, 2H), 7.61–7.63 (m, 2H), 10.47
(s, 1H, NH); 13C NMR [100 MHz, (CD3)2SO]: d 20.82, 109.32, 116.92, 118.05,
121.95, 124.39, 129.81, 131.45, 136.66, 142.98, 147.45, 158.55; MS (m=z): 225.47
(Mþ1). C14H12N2O calcd. C, 74.98; H, 5.39; N, 12.49; Found: C, 75.01; H, 5.40;
N, 12.48.
N-(3,4-Dimethyl phenyl)benzoxazol-2-amine (3i). Yield: 76%, white solid;
1
mp 150–151 ꢀC; H NMR [400 MHz, (CD3)2SO] d 2.08 (s, 6H), 7.06–7.13 (m, 2H),
7.19–7.24 (m, 1H), 7.43–7.52 (m, 4H), 10.40 (s, 1H, NH); 13C NMR [100 MHz,
(CD3)2SO]: d 19.15, 20.18, 109.27, 115.60, 116.91, 119.26, 121.88, 124.36, 125.61,
130.29, 137.04, 136.89, 143.05, 147.46, 158.58; MS (m=z): 239.33 (Mþ1).
C15H14N2O calcd. C, 75.61; H, 5.92; N, 11.76. Found: C, 75.63; H, 5.95; N, 11.77.
N-Benzyl-2-aminobenzoxazole (3j). Yield: 74%, white solid; mp
1
104–106 ꢀC; H NMR [400 MHz, (CD3)2SO] d 4.50 (d, J ¼ 6.0 Hz, 2H), 6.94–6.98
(m, 1H), 7.07–7.11 (m, 1H), 7.21–7.25 (m, 2H), 7.30–7.37 (m, 5H), 8.48 (t, J ¼ 6.0 Hz,
1H, NH); 13C NMR [100 MHz, (CD3)2SO]: d 46.10, 109.04, 115.97, 119.97, 120.74,
124.12, 127.62, 128.84, 139.45, 143.48, 148.52, 162.88; MS (m=z): 225.20 (Mþ1).
C14H12N2O calcd. C, 74.98; H, 5.39; N, 12.49. Found: C, 75.02; H, 5.43; N, 12.51.
N-(1-Phenylethyl)benzoxazol-2-amine (3k). Yield: 73%, white solid; mp
1
49–52 ꢀC; H NMR [400 MHz, (CD3)2SO] d 1.49 (d, J ¼ 6.8 Hz, 3H), 4.89–4.97 (m,
1H), 6.96 (t, J ¼ 7.6 Hz, 1H), 7.08 (t, J ¼ 7.8 Hz, 1H), 7.19–7.25 (m, 2H), 7.33 (t,
J ¼ 7.8 Hz, 3H), 7.42 (d, J ¼ 7.6 Hz, 2H), 8.50 (d, 1H, NH); 13C NMR [100 MHz,
(CD3)2SO]: d 23.48, 52.69, 108.97, 115.93, 120.70, 124.05, 126.04, 127.33, 128.81,