The Journal of Organic Chemistry
NOTE
1.26 (t, J = 7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ (ppm) 162.4,
147.0, 143.8, 133.4, 120.6, 116.3, 107.9, 43.0, 21.6, 13.8; HRMS (ESI)
calcd for C12H16N2O [M þ H]þ 205.1341, found 205.1338.
isolated yield; 1H NMR (400 MHz, CDCl3) δ (ppm) 7.37ꢀ7.39
(m, 2H), 7.14ꢀ7.26 (m, 5H), 7.01 (t, J = 8.0 Hz, 1H), 4.87 (s, 2H),
3.18 (s, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm) 162.9, 149.1,
143.5, 134.0, 133.5, 129.8, 128.9, 128.4, 127.2, 124.1, 120.6, 116.3, 108.9,
51.4, 35.8; HRMS (ESI) calcd for C15H13ClN2O [M þ H]þ 273.0795,
found 273.0798; mp 82ꢀ84 °C.
5-Chloro-N,N-diethylbenzoxazol-2-amine (4i). The title compound
was prepared according to the general procedure for amination of
benzoxazoles with formamides to give a yellow liquid: 29% isolated
yield; 1H NMR (400 MHz, CDCl3) δ (ppm) 7.29 (s, 1H), 7.12
(d, J = 8.4 Hz, 1H), 6.93 (d, J = 8.4 Hz, 1H), 3.54ꢀ3.59 (q, 4H), 1.28
(t, J = 7.2 Hz, 6H); 13C NMR (100 MHz, CDCl3) δ (ppm) 163.0, 147.5,
145.1, 129.1, 119.8, 115.9, 109.0, 43.0, 13.5; HRMS (ESI) calcd for
C11H13ClN2O [M þ H]þ 225.0795, found 225.0788.
N,N-Dibutyl-5-methylbenzoxazol-2-amine (6a). The title com-
pound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a white solid: 94%
isolated yield; 1H NMR (400 MHz, CDCl3) δ (ppm) 7.15 (s, 1H), 7.09
(d, J = 8.0 Hz, 1H), 6.75 (d, J = 8.0 Hz, 1H), 3.48 (t, J = 7.6 Hz, 4H), 2.37
(s, 3H), 1.60ꢀ1.67 (m, 4H), 1.32ꢀ1.41 (m, 4H), 0.95 (t, J = 7.2 Hz,
6H); 13C NMR (100 MHz, CDCl3) δ (ppm) 162.8, 146.9, 143.9, 133.2,
120.4, 116.2, 107.8, 48.3, 30.1, 21.5, 20.0, 13.9; HRMS (ESI) calcd for
C16H24N2O [M þ H]þ 261.1967, found 261.1969; mp 73ꢀ75 °C.
5-tert-Butyl-N,N-dibutylbenzoxazol-2-amine (6b). The title com-
pound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a yellow liquid: 84%
isolated yield; 1H NMR (400 MHz, CDCl3) δ (ppm) 7.44 (s, 1H), 7.14
(d, J = 8.4 Hz, 1H), 7.01 (d, J = 8.4 Hz, 1H), 3.49 (t, J = 7.2 Hz, 4H),
1.61ꢀ1.68 (m, 4H), 1.33ꢀ1.40 (m, 13H), 0.95 (t, J = 7.2 Hz, 6H); 13C
NMR (100 MHz, CDCl3) δ (ppm) 162.9, 147.1, 146.7, 143.5, 116.9,
113.0, 107.5, 48.3, 34.8, 31.9, 30.2, 20.0, 13.9; HRMS (ESI) calcd for
C19H30N2O [M þ H]þ 303.2436, found 303.2444.
2-Morpholinobenzoxazole7c (5a). The title compound was prepared
according to the general procedure for direct amination of benzoxazoles
1
with amines to give a yellow solid: 55% isolated yield; H NMR (400
MHz, CDCl3) δ (ppm) 7.38 (d, J = 8.0 Hz, 1H), 7.26 (d, J = 8.0 Hz, 1H),
7.17 (t, J = 8.0 Hz, 1H), 7.04 (t, J = 8.0 Hz, 1H), 3.81 (t, J = 4.4 Hz, 4H),
3.68 (t, J = 4.4 Hz, 4H); 13C NMR (100 MHz, CDCl3) δ (ppm) 162.1,
148.8, 142.9, 124.2, 121.0, 116.6, 108.9, 66.3, 45.8; HRMS (ESI) calcd
for C11H12N2O2 [M þ H]þ 205.0977, found 205.0977.
2-(Piperidin-1-yl)benzoxazole7c (5b). The title compound was pre-
pared according to the general procedure for direct amination of
benzoxazoles with amines to give a yellow solid: 84% isolated yield;
1H NMR (400 MHz, CDCl3) δ (ppm) 7.34 (d, j = 8.0 Hz, 1H), 7.21 (d,
J = 8.0 Hz, 1H), 7.13 (t, J = 8.0 Hz, 1H), 6.97 (t, J = 8.0 Hz, 1H),
3.61ꢀ3.62 (m, 4H), 1.63 (s, 6H); 13C NMR (100 MHz, CDCl3) δ
(ppm) 162.3, 148.6, 143.3, 123.7, 120.2, 115.9, 108.5, 46.5, 25.1, 24.0;
GCꢀMS (EI) m/z = 202 [M]þ.
N,N-Dibutyl-5-chlorobenzoxazol-2-amine (6c). The title compound
was prepared according to the general procedure for direct amination of
benzoxazoles with amines to give a yellow solid: 76% isolated yield; 1H
NMR (400 MHz, CDCl3) δ (ppm) 7.28 (s, 1H), 7.11 (d, J = 8.4 Hz,
1H), 6.91 (d, J = 8.4 Hz, 1H), 3.48 (t, J = 7.6 Hz, 4H), 1.60ꢀ1.68 (m,
4H), 1.32ꢀ1.41 (m, 4H), 0.96 (t, J = 7.2 Hz, 6H); 13C NMR (100 MHz,
CDCl3) δ (ppm) 163.4, 147.4, 145.2, 129.0, 119.6, 115.8, 108.9, 48.4,
30.1, 20.0, 13.9; HRMS (ESI) calcd for C15H21ClN2O [M þ H]þ
281.1421, found 281.1425; mp 63ꢀ65 °C.
N,N-Dibutylbenzoxazol-2-amine7c (5c). The title compound was
prepared according to the general procedure for direct amination of
benzoxazoles with amines to give a yellow liquid: 85% isolated yield; 1H
NMR (400 MHz, CDCl3) δ (ppm) 7.35 (d, J = 8.0 Hz, 1H), 7.22 (d, J =
8.0 Hz, 1H), 7.12 (t, J = 8.0 Hz, 1H), 6.95 (t, J = 8.0 Hz, 1H), 3.46ꢀ3.50
(t, 4H), 1.60ꢀ1.68 (m, 4H), 1.32ꢀ1.41 (m, 4H), 0.95 (t, J = 7.6 Hz,
6H); 13C NMR (100 MHz, CDCl3) δ (ppm) 162.6, 148.7, 143.7, 123.7,
119.8, 115.7, 108.4, 48.3, 30.1, 20.0, 13.8; GCꢀMS (EI) m/z = 246
[M]þ.
N,N-Dibutyloxazolo[4,5-b]pyridin-2-amine (6d). The title com-
pound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a yellow liquid: 48%
isolated yield; 1H NMR (400 MHz, CDCl3) δ (ppm) 8.19 (S, 1H), 7.39
(d, J = 7.6 Hz, 1H), 6.84ꢀ6.87 (m, 1H), 3.54 (t, J = 7.2 Hz, 4H),
1.64ꢀ1.71 (m, 4H), 1.33ꢀ1.43 (m, 4H), 0.96 (t, J = 7.2 Hz, 6H); 13C
NMR (100 MHz, CDCl3) δ (ppm) 164.1, 158.8, 144.4, 141.4, 115.0,
114.4, 48.5, 30.1, 20.0, 13.9; HRMS (ESI) calcd for C14H21N3O [M þ
H]þ 248.1763, found 248.1764.
2-(4-Methylpiperdin-1-yl)benzoxazole (5d). The title compound
was prepared according to the general procedure for direct amination
of benzoxazoles with amines to give a white solid: 83% isolated yield; 1H
NMR (400 MHz, CDCl3) δ (ppm) 7.34 (d, J = 7.6 Hz, 1H), 7.22 (d, J =
8.0 Hz, 1H), 7.13 (t, J = 7.6 Hz, 1H), 6.97 (t, J = 8.0 Hz, 1H), 4.25 (d, J =
13.2 Hz, 2H), 3.02 (t, J = 12 Hz, 2H), 1.71 (d, J = 12.8 Hz, 2H),
1.57ꢀ1.60 (m, 1H), 1.19ꢀ1.30 (m, 2H), 0.96 (d, j = 6.4 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ (ppm) 162.4, 148.7, 143.4, 123.8, 120.2,
116.0, 108.5, 46.0, 33.6, 21.8; HRMS (ESI) calcd for C13H16N2O [M þ
H]þ 217.1341, found 217.1340; mp 65ꢀ67 °C.
N-Benzyl-N,5-dimethylbenzoxazol-2-amine (6e). The title com-
pound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a yellow solid: 78%
1
isolated yield; H NMR (400 MHz, CDCl3) δ (ppm) 7.25ꢀ7.32 (m,
2-(Pyrrolidin-1-yl)benzoxazole13 (5e). The title compound was pre-
pared according to the general procedure for direct amination of benzox-
azoles with amines to give a white solid: 45% isolated yield; 1H NMR (400
MHz, CDCl3) δ (ppm) 7.36 (d, J = 7.6 Hz, 1H), 7.24 (d, J = 7.6 Hz, 1H),
7.14 (t, J= 7.6 Hz, 1H), 6.98 (t, J= 7.6 Hz, 1H), 3.64 (t, J = 6.4 Hz, 4H), 2.02
(t, J = 6.4 Hz, 4H); 13C NMR (100 MHz, CDCl3) δ (ppm) 161.1, 149.1,
143.7, 123.9, 120.1, 116.0, 108.6, 47.5, 25.7; GCꢀMS (EI) m/z=188[M]þ.
N-Benzyl-N-methylbenzoxazol-2-amine13 (5f). The title compound
was prepared according to the general procedure for direct amination of
benzoxazoles with amines to give a yellow solid: 65% isolated yield; 1H
NMR (400 MHz, CDCl3) δ (ppm) 7.39 (d, J = 7.6 Hz, 1H), 7.23ꢀ7.34
(m, 6H), 7.17 (t, J = 7.6 Hz, 1H), 7.01 (t, J = 7.6 Hz, 1H), 4.74 (s, 2H),
3.11 (s, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm) 163.0, 149.0,
143.6, 136.5, 128.8, 127.8, 127.7, 124.0, 120.5, 116.2, 108.8, 53.9, 35.2;
GCꢀMS (EI) m/z = 238 [M]þ.
5H), 7.18 (s, 1H), 7.11 (d, J = 8.0 Hz, 1H), 6.80 (d, J = 8.0 Hz, 1H), 4.70
(s, 2H), 3.08 (s, 3H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3) δ
(ppm) 163.1, 147.2, 143.7, 136.5, 133.6, 128.7, 127.7, 127.6, 121.0,
116.6, 108.1, 53.8, 35.1, 21.6; HRMS (ESI) calcd for C16H16N2O [M þ
1] 253.1341, found 253.1342; mp 55ꢀ57 °C.
N-Benzyl-5-chloro-N-methylbenzoxazol-2-amine14 (6f). The title
compound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a yellow solid: 75%
1
isolated yield; H NMR (400 MHz, CDCl3) δ (ppm) 7.26ꢀ7.32 (m,
6H), 7.12 (d, J = 8.4 Hz, 1H), 6.94 (d, J = 8.4 Hz, 1H), 4.70 (s, 2H), 3.09
(s, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm) 163.7, 147.6, 145.0,
136.1, 129.2, 128.8, 127.9, 127.7, 120.1, 116.2, 109.2, 53.8, 35.1; HRMS
(ESI) calcd for C15H13ClN2O [M þ H]þ 273.0795, found 273.0793.
5-Methylbenzoxazole: light yellow solid; 62% isolated yield; 1H
NMR (400 MHz, CDCl3) δ (ppm) 8.04 (s, 1H), 7.55 (s, 1H), 7.40
(d, J = 8.0 Hz, 1H), 7.13 (d, J = 8.0 Hz, 1H), 2.42 (s, 3H); 13C NMR (100
MHz, CDCl3) δ (ppm) 152.5, 148.0, 140.1, 134.1, 126.5, 120.2, 110.0,
21.2; GCꢀMS (EI) m/z = 133 [M]þ.
N-(2-Chorobenzyl)-N-methylbenzoxazol-2-amine (5g). The title
compound was prepared according to the general procedure for direct
amination of benzoxazoles with amines to give a yellow solid: 57%
5448
dx.doi.org/10.1021/jo200447x |J. Org. Chem. 2011, 76, 5444–5449