CDCl ): ¤ 3.70 (s, 3H), 6.83 (dd, J = 8.8, 2.0 Hz, 2H), 7.19
CDCl ): ¤ 7.357.59 (m, 5H), 7.767.80 (m, 1H), 8.14 (d,
3
3
1
3
7
7
1
1
6
.23 (m, 1H), 7.297.32 (m, 1H), 7.71 (d, J = 7.9 Hz, 1H),
J = 7.1 Hz, 1H), 8.25 (s, 1H). C NMR (62.9 MHz, CDCl ): ¤
3
.867.91 (m, 3H). 13C NMR (62.9 MHz, CDCl ): ¤ 167.8,
162.4, 150.4, 141.9, 135.0, 131.4, 130.2, 128.8, 127.5, 125.6,
3
61.9, 154.1, 153.1, 136.6, 134.8, 129.1, 126.3, 124.7, 122.8,
125.5, 124.8, 120.2, 110.7. Anal. Calcd for C H ClNO: C,
1
3
8
21.5, 114.3, 113.5, 55.4. Anal. Calcd for C H NOS: C,
67.99; H, 3.51; N, 6.10%. Found: C, 68.08; H, 3.69; N, 5.88%.
14
11
2
6i
9.68; H, 4.59; N, 5.80%. Found: C, 69.51; H, 4.40; N, 6.04%.
2-(4-Bromophenyl)-1,3-benzoxazole (6f):
White solid;
2
6f
1
2
-Methylbenzothiazole (4k):
Colorless oil; yield: 91 mg
yield: 195 mg (71%); mp 158160 °C. H NMR (250 MHz,
1
(61%). H NMR (250 MHz, CDCl ): ¤ 2.58 (s, 3H), 7.117.20
CDCl ): ¤ 7.307.35 (m, 2H), 7.517.61 (m, 3H), 7.717.75
3
3
1
3
(
m, 1H), 7.237.30 (m, 1H), 7.587.64 (m, 1H), 7.777.83 (m,
(m, 1H), 8.05 (d, J = 8.6 Hz, 1H). C NMR (62.9 MHz,
1
3
1
1
6
H). C NMR (62.9 MHz, CDCl ): ¤ 168.2, 154.2, 141.3,
CDCl ): ¤ 162.0, 150.6, 141.9, 132.1, 128.9, 126.1, 126.0,
3
3
35.0, 131.0, 128.7, 123.6, 21.5. Anal. Calcd for C H NS: C,
125.3, 124.7, 120.0, 110.6. Anal. Calcd for C H BrNO: C,
8
7
13
8
4.40; H, 4.73; N, 9.39%. Found: C, 64.54; H, 4.60; N, 9.48%.
56.96; H, 2.94; N, 5.11%. Found: C, 56.80; H, 3.07; N, 5.24%.
4a
26k
2
-Eethylbenzothiazole (4l):
Colorless oil; yield: 91 mg
2-(2-Hydroxyphenyl)-1,3-benzoxazole (6g):
White
1
1
(56%). H NMR (250 MHz, CDCl ): ¤ 1.17 (t, J = 7.6 Hz, 3H),
solid; yield: 131 mg (62%); mp 122124 °C. H NMR (250
MHz, CDCl3): ¤ 6.906.96 (m, 1H), 7.107.13 (m, 1H). 7.34
7.50 (m, 3H), 7.64 (d, J = 7.8 Hz, 1H), 7.83 (d, J = 7.8 Hz,
3
2
7
.85 (q, J = 7.6 Hz, 2H), 7.007.18 (m, 2H), 7.52 (d, J =
.9 Hz, 1H), 7.72 (d, J = 7.6 Hz, 1H). 13C NMR (62.9 MHz,
1
3
CDCl ): ¤ 173.4, 153.2, 135.0, 125.8, 124.5, 122.4, 121.4,
1H), 7.95 (d, J = 8.1 Hz, 1H) 9.63 (s, 1H). C NMR (62.9
3
2
8
9.7, 13.7. Anal. Calcd for C H NS: C, 66.22; H, 5.56; N,
MHz, CDCl ): ¤ 162.8, 158.7, 149.0, 139.9, 133.5, 127.0,
9
9
3
.58%. Found: C, 66.13; H, 5.50; N, 8.79%.
125.3, 124.9, 119.5, 118.5, 117.3, 116.8, 110.6. Anal. Calcd for
C H NO : C, 73.92; H, 4.30; N, 6.63%. Found: C, 73.87; H,
2
6f
2
-Benzylbenzothiazole (4m):
Yellow solid; yield:
1
3
9
2
1
1
¤
7
1
1
7
55 mg (69%); mp 157159 °C. H NMR (250 MHz, CDCl ):
4.45; N, 6.54%.
2-(3-Hydroxyphenyl)-1,3-benzoxazole (6h):
solid; yield: 139 mg (66%); mp 230232 °C. H NMR (250
3
2
6i
4.18 (s, 2H), 7.027.22 (m, 7H), 7.50 (d, J = 7.9 Hz, 1H),
.82 (d, J = 8.1 Hz, 1H). 13C NMR (62.9 MHz, CDCl3): ¤
71.1, 153.7, 137.2, 135.7, 131.3, 129.6, 129.0, 128.5, 127.4,
26.4, 126.0, 124.8, 121.6, 40.6. Anal. Calcd for C H NS: C,
White
1
MHz, CDCl ): ¤ 6.997.02 (m, 1H), 7.327.40 (m, 3H), 7.67
3
1
3
7.73 (m, 4H), 10.02 (br s, 1H). C NMR (62.9 MHz, CDCl ): ¤
14
11
3
4.63; H, 4.92; N, 6.22%. Found: C, 74.70; H, 5.05; N, 6.08%.
167.4, 162.2, 158.1, 151.7, 150.0, 141.3, 130.3, 129.4, 127.4,
26i
2
-Phenyl-1,3-benzoxazole (6a):
White solid; yield:
125.2, 120.5, 115.8, 110.7. Anal. Calcd for C H NO : C,
1
3
9
2
1
1
7
8
1
1
7
62 mg (83%); mp 121123 °C. H NMR (250 MHz, CDCl ): ¤
73.92; H, 4.30; N, 6.63%. Found: C, 73.80; H, 4.38; N, 6.59%.
3
2
6i
.197.22 (m, 2H), 7.367.41 (m, 4H), 7.607.67 (m, 1H),
2-(4-Hydroxyphenyl)-1,3-benzoxazole (6i):
White
.118.15 (m, 2H). 13C NMR (62.9 MHz, CDCl ): ¤ 163.0,
solid; yield: 133 mg (63%); mp 255257 °C. H NMR (250
MHz, CDCl3): ¤ 6.96 (d, J = 8.7 Hz, 2H), 7.30 (dd, J = 6.0,
3.2 Hz, 2H), 7.627.69 (m, 2H), 8.02 (d, J = 8.7 Hz, 2H).
1
3
50.7, 142.0, 131.4, 128.8, 128.3, 127.6, 127.1, 125.0, 124.5,
20.0, 110.5. Anal. Calcd for C H NO: C, 79.98; H, 4.65; N,
.17%. Found: C, 80.23; H, 4.73; N, 6.96%.
13
9
1
3
C NMR (62.9 MHz, CDCl ): ¤ 167.9, 166.1, 155.2, 146.9,
3
26j
2
-(2-Nitrophenyl)-1,3-benzoxazole (6b):
Yellow solid;
134.4, 134.0, 129.8, 129.6, 124.3, 122.3, 121.2, 116.1, 115.3.
1
yield: 204 mg (85%); mp 105107 °C. H NMR (250 MHz,
Anal. Calcd for C H NO : C, 73.92; H, 4.30; N, 6.63%.
1
3
9
2
CDCl ): ¤ 7.387.47 (m, 2H), 7.64 (d, J = 8.9 Hz, 1H), 7.83 (d,
Found: C, 74.04; H, 4.19; N, 6.52%.
3
J = 8.6 Hz, 1H), 8.368.46 (m, 4H). 13C NMR (62.9 MHz,
2-Methyl-1,3-benzoxazole (6j):
26i
Yellow oil; yield: 74 mg
1
CDCl ): ¤ 165.9, 154.2, 137.9, 135.4, 132.7, 130.0, 128.5,
(56%). H NMR (250 MHz, CDCl ): ¤ 2.54 (s, 3H), 7.187.22
3
3
(m, 2H), 7.367.40 (m, 1H), 7.557.58 (m, 1H). 1 C NMR
3
1
6
26.2, 125.0, 124.4, 121.6. Anal. Calcd for C13H8N2O3: C,
5.00; H, 3.36; N, 11.66%. Found: C, 65.32; H, 3.04; N,
(62.9 MHz, CDCl ): ¤ 163.2, 150.6, 141.3, 125.9, 124.9, 124.2,
3
1
1.44%.
2
119.4, 109.6.
-(3-Nitrophenyl)-1,3-benzoxazole (6c):2
6j
White solid;
2-Ethyl-1,3-benzoxazole (6k):
26i
Yellow oil; yield: 58 mg
1
1
yield: 209 mg (87%); mp 210212 °C. H NMR (250 MHz,
(39%). H NMR (250 MHz, CDCl ): ¤ 1.39 (t, J = 7.6 Hz, 3H),
3
CDCl ): ¤ 7.397.42 (m, 2H), 7.617.82 (m, 3H), 8.37 (d, J =
8
2.89 (q, J = 7.6 Hz, 2H), 7.197.25 (m, 2H), 7.387.42 (m,
3
.1 Hz, 1H), 8.57 (d, J = 7.6 Hz, 1H), 9.08 (s, 1H). 1 C NMR
3
1H), 7.587.62 (m, 1H). C NMR (62.9 MHz, CDCl ): ¤
13
3
(
1
62.9 MHz, CDCl ): ¤ 160.8, 151.8, 147.2, 140.9, 132.8, 130.3,
29.0, 125.9, 125.2, 124.7, 120.4, 118.1, 112.1. Anal. Calcd for
168.1, 150.7, 141.2, 124.4, 124.0, 119.4, 110.2, 22.1, 10.8.
3
2
6h
2-Benzyl-1,3-benzoxazole (6l):
92 mg (44%); mp 108110 °C. H NMR (250 MHz, CDCl ): ¤
4.28 (s, 2H), 7.277.46 (m, 8H), 7.728.03 (m, 1H). 1 C NMR
Yellow solid; yield:
1
C H N O : C, 65.00; H, 3.36; N, 11.66%. Found: C, 64.90; H,
3
13
8
2
3
3
3
.21; N, 11.79%.
2
-(2-Chlorophenyl)-1,3-benzoxazole (6d):26i White solid;
(62.9 MHz, CDCl ): ¤ 165.2, 151.0, 141.4, 134.8, 128.9, 127.6,
3
yield: 184 mg (80%); mp 6466 °C. 1H NMR (250 MHz,
126.9, 125.9, 124.5, 121.1, 119.8, 110.4, 35.3.
CDCl ): ¤ 7.167.20 (m, 4H), 7.317.39 (m, 2H), 7.67 (d,
General Procedure for the Synthesis of Benzimidazoles 2
from Alcohols in PEG-200. A 5 mL flask equipped with a
stirrer bar was charged with the alcohol (1.2 mmol), GO (300
wt %) and 2 mL of PEG-200. The resulting mixture was heated
at 110 °C until almost all alcohols were oxidized. After almost
complete oxidation of the starting alcohol to aldehyde, 1 mmol
of o-phenylenediamine 1a was added and allow the reaction
mixture to stir at 110 °C until the consumption of o-phenyl-
3
J = 5.9 Hz, 1H), 7.927.96 (m, 1H). 13C NMR (62.9 MHz,
CDCl ): ¤ 160.8, 150.4, 141.6, 133.3, 131.8, 130.0, 127.4,
3
1
26.8, 126.1, 125.5, 124.6, 120.4, 111.0. Anal. Calcd for
C H ClNO: C, 67.99; H, 3.51; N, 6.10%. Found: C, 68.11; H,
13
8
3
.43; N, 6.24%.
-(3-Chlorophenyl)-1,3-benzoxazole (6e):26i White solid;
yield: 172 mg (75%); mp 124126 °C. 1H NMR (250 MHz,
2
© 2015 The Chemical Society of Japan