584
A. B. Naidu, G. Sekar
PAPER
with a septum. The reaction tube was evacuated and backfilled with
nitrogen. MeCN (2.5 mL) was added to the mixture at r.t. and the
mixture was heated at 82 °C for 14 h. After complete disappearance
of N-(2-iodophenyl)benzamide (progress of the reaction was fol-
lowed by TLC), the mixture was allowed to cool to r.t. and the sol-
vent was removed by evaporation. The crude residue was directly
purified by column chromatography on silica gel (EtOAc–hexanes)
to afford 2-phenylbenzoxazole12a as a white solid; yield: 84 mg
(86%).
Mp 100–101 °C (Lit.12a 101–102 °C); Rf = 0.70 (hexanes–EtOAc,
9:1).
FTIR (neat): 760, 1242, 1552, 2922, 3100 cm–1.
13C NMR (100 MHz, CDCl3): d = 55.6, 110.5, 114.5, 119.7, 119.8,
124.5, 124.7, 129.5, 142.4, 150.8, 162.5, 163.3.
HRMS: m/z [M + H+] calcd for C14H12NO2: 226.0868; found:
226.0864.
2-(4-Bromophenyl)benzoxazole12a (Table 3, Entry 6)
White solid; mp 155–158 °C (Lit.12a 157–158 °C); Rf = 0.57 (hex-
anes–EtOAc, 9:1).
IR (neat): 829, 1069, 1244, 1591, 3057 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.34–7.41 (m, 2 H), 7.54–7.61 (m,
1 H), 7.65–7.70 (m, 2 H), 7.75–7.80 (m, 1 H), 8.09–8.15 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 110.7, 120.2, 124.8, 125.4, 126.1,
126.3, 129.0, 132.3, 142.1, 150.8, 162.2.
HRMS: m/z [M + H+] calcd for C13H9NOBr: 273.9868; found:
273.9860.
1H NMR (400 MHz, CDCl3): d = 7.32–7.38 (m, 2 H), 7.49–7.55 (m,
2 H), 7.56–7.60 (m, 2 H), 7.76–7.82 (m, 1 H), 8.23–8.30 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 110.7, 120.1, 124.7, 125.2, 127.3,
127.7, 129.0, 131.6, 142.2, 150.8, 163.1.
HRMS: m/z [M + H+] calcd for C13H10NO: 196.0762; found:
196.0763.
2-(3-Bromophenyl)benzoxazole19 (Table 3, Entry 7)
White solid; mp 127–128 °C (Lit.19 128–130 °C); Rf = 0.63 (hex-
anes–EtOAc, 9:1).
2-o-Tolylbenzoxazole11a (Table 3, Entry 2)
White solid; mp 69–70 °C (Lit.11a 68–69 °C); Rf = 0.67 (hexanes–
EtOAc, 9:1).
FTIR (neat): 744, 1241, 1548, 2921, 3100 cm–1.
1H NMR (400 MHz, CDCl3): d = 2.83 (s, 3 H), 7.32–7.45 (m, 5 H),
7.57–7.63 (m, 1 H), 7.80–7.85 (m, 1 H), 8.17–8.23 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 22.3, 110.6, 120.2, 124.5, 125.1,
126.1, 126.3, 130.0, 130.9, 131.9, 138.9, 142.2, 150.4, 163.5.
HRMS: m/z [M + H+] calcd for C14H12NO: 210.0919; found:
210.0920.
FTIR (neat): 737, 1070, 1241, 1570, 3057 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.32–7.39 (m, 3 H), 7.53–7.59 (m,
1 H), 7.60–7.65 (m, 1 H), 7.73–7.79 (m, 1 H), 8.12–8.17 (m, 1 H),
8.38 (t, J = 1.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 110.8, 120.3, 123.1, 124.9, 125.6,
126.1, 129.1, 130.5, 130.6, 134.4, 142.0, 150.8, 161.5.
HRMS: m/z [M + H+] calcd for C13H9NOBr: 273.9868; found:
273.9860.
2-(4-Fluorophenyl)benzoxazole20 (Table 3, Entry 8)
White solid; mp 95–96 °C (Lit.20 94–95 °C); Rf = 0.62 (hexanes–
EtOAc, 9:1).
FTIR (neat): 741, 1054, 1245, 1600, 3061 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.16–7.23 (m, 2 H), 7.31–7.38 (m,
2 H), 7.52–7.59 (m, 1 H), 7.71–7.79 (m, 1 H), 8.20–8.28 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 110.7, 116.2, 116.4, 120.1, 124.8,
125.3, 129.9, 130.0, 142.2, 150.9, 166.2.
HRMS: m/z [M + H+] calcd for C13H9NOF: 214.0668; found:
214.0665.
2-(2-Methoxyphenyl)benzoxazole12a (Table 3, Entry 3)
White solid; mp 50–52 °C (Lit.12a 53–55 °C); Rf = 0.25 (hexanes–
EtOAc, 9:1).
IR (neat): 748, 1248, 1548, 2922, 3050 cm–1.
1H NMR (400 MHz, CDCl3): d = 4.00 (s, 3 H), 7.05–7.13 (m, 2 H),
7.30–7.37 (m, 2 H), 7.46–7.52 (m, 1 H), 7.58 (dd, J = 3.2, 6.0 Hz, 1
H), 7.82 (dd, J = 3.2, 6.0 Hz, 1 H), 8.14 (dd, J = 2.0, 8.0 Hz, 1 H).
13C NMR (100 MHz, CDCl3): d = 56.4, 110.6, 112.3, 116.4, 120.4,
120.6, 120.9, 124.4, 125.1, 131.5, 132.9, 142.3, 150.5, 158.6.
HRMS: m/z [M + H+] calcd for C14H12NO2: 226.0868; found:
226.0874.
2-(4-Chlorophenyl)benzoxazole11a (Table 3, Entry 9)
White solid; mp 140–142 °C (Lit.11a 144–145 °C); Rf = 0.66 (hex-
anes–EtOAc, 9:1).
2-(3-Methoxyphenyl)benzoxazole (Table 3, Entry 4)
White solid; mp 52–55 °C; Rf = 0.45 (hexanes–EtOAc, 9:1).
IR (neat): 741, 1234, 1551, 2923, 3100 cm–1.
1H NMR (400 MHz, CDCl3): d = 3.90 (s, 3 H), 7.07 (dd, J = 2.4, 8
Hz, 1 H), 7.31–7.37 (m, 2 H), 7.41 (t, J = 8 Hz, 1 H), 7.54–7.59 (m,
1 H), 7.75–7.80 (m, 2 H), 7.82–7.86 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 55.6, 110.7, 112.0, 118.4, 120.1,
120.2, 124.7, 125.2, 128.4, 130.1, 142.1, 150.8, 160.0, 163.0.
FTIR (neat): 832, 1091, 1244, 1596, 3100 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.31–7.37 (m, 2 H), 7.43–7.49 (m,
2 H), 7.51–7.57 (m, 1 H), 7.72–7.78 (m, 1 H), 8.12–8.17 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 110.7, 120.2, 124.8, 125.4, 125.7,
128.9, 129.3, 137.8, 142.0, 150.8, 162.0.
HRMS: m/z [M + H+] calcd for C13H9NOCl: 230.0373; found:
230.0369.
HRMS: m/z [M + H+] calcd for C14H12NO2: 226.0868; found:
226.0874.
2-(3-Chlorophenyl)benzoxazole19 (Table 3, Entry 10)
White solid; mp 122 °C (Lit.19 124–125 °C); Rf = 0.61 (hexanes–
EtOAc, 9:1).
IR (neat): 745, 1080, 1244, 1590, 3100 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.30–7.50 (m, 4 H), 7.51–7.59 (m,
1 H), 7.72–7.80 (m, 1 H), 8.06–8.13 (m, 1 H), 8.19–8.25 (m, 1 H).
2-(4-Methoxyphenyl)benzoxazole12a (Table 3, Entry 5)
White solid; mp 97 °C (Lit.12a 97–98 °C); Rf = 0.38 (hexanes–
EtOAc, 9:1).
FTIR (neat): 786, 1282, 1583, 2923, 3050 cm–1.
13C NMR (100 MHz, CDCl3): d = 110.8, 120.3, 124.9, 125.6, 125.7,
127.7, 128.9, 130.3, 131.5, 135.1, 142.0, 150.8, 161.7.
1H NMR (400 MHz, CDCl3): d = 3.83 (s, 3 H), 6.98 (d, J = 8.8 Hz,
2 H), 7.25–7.34 (m, 2 H), 7.49–7.54 (m, 1 H), 7.69–7.76 (m, 1 H),
8.16 (d, J = 8.4 Hz, 2 H).
Synthesis 2010, No. 4, 579–586 © Thieme Stuttgart · New York