W. Chen et al. / Tetrahedron 71 (2015) 9240e9244
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4.2. Typical procedure for hydrogenation of 4-methylphenyl
4-nitrobenzyl ether (2a) to 4-methylphenyl 4-aminobenzyl
ether (1a)
(m, 2H), 6.80e6.75 (m, 3H), 5.04 (s, 2H), 3.71 (s, 2H), 2.55 (s, 3H);
13C NMR (CDCl3, 100 MHz)
196.8, 162.6, 146.7, 137.3, 130.5 (2C),
130.3, 129.5, 117.3, 114.8, 114.4 (2C), 113.7, 70.0, 26.2.
d
A mixture of 2a (243 mg, 1 mmol) and 1% Pd/Ni bimetallic
catalyst (73 mg, 30 wt %) in MeOH (10 mL) was stirred under H2 at
room temperature and atmospheric pressure (on an atmospheric
pressure hydrogenation apparatus) until the absorption of hydro-
gen ceased (90 min). After the catalyst was removed off by a mag-
netic stirring bar, the solution was evaporated on a rotavapor to
give the product 1a as yellowish oil (210 mg, 98%), which is pure
enough for 1H and 13C NMR determinations. IR (KBr) v 3372, 1623,
4.9. 4-Methoxycarbonylphenyl 5-chloro-2-aminobenzyl ether
(1h)
Yellowish oil.13e 1H NMR (CDCl3, 300 MHz)
7.19e6.98 (m, 4H), 6.67e6.64 (m, 1H), 5.02 (s, 2H), 4.01 (s, 2H), 3.89
(s, 3H); 13C NMR (CDCl3, 100 MHz)
166.6, 161.7, 144.4, 131.5 (2C),
d 8.02e7.99 (m, 2H),
d
129.6, 129.5, 123.2, 122.7, 121.6, 117.3, 114.3 (2C), 68.3, 51.8.
1519, 1233 cmꢀ1 1H NMR (CDCl3, 400 MHz)
; d 7.26e7.20 (m, 2H),
4.10. 2-Chlorophenyl 2-aminobenzyl ether (1i)
7.06 (d, 2H, J¼11.0 Hz), 6.87 (d, 2H, J¼11.0 Hz), 6.69 (d, 2H,
J¼11.0 Hz), 4.90 (s, 2H), 3.69 (s, 2H), 2.28 (s, 3H); 13C NMR (CDCl3,
Yellowish oil. IR (KBr) v 3442, 1622, 1511, 1235 cmꢀ1
(CDCl3, 300 MHz)
6.73e7.27 (m, 8H), 5.14 (s, 2H), 4.25 (s, 2H); 13
NMR (CDCl3, 100 MHz) 153.6, 146.5, 130.3, 130.1, 129.9, 127.6,
;
1H NMR
100 MHz)
d 156.8, 146.3, 129.7 (2C), 126.8, 115.0 (2C), 114.6 (2C),
d
C
70.1, 20.4. HRMS (ESI-TOF) (m/z): calcd for C14H15NO, [MþNa]þ:
d
236.1046, found: 236.1044.
123.2, 121.9, 120.4, 118.1, 116.3, 114.3, 70.4. HRMS (ESI-TOF) (m/z):
calcd for C13H12ClNO, [MþH]þ: 234.0680, found: 234.0676.
The similar procedure was used for the chemoselective hydro-
genation of 2be2u to 1be1u. In some cases, flash chromatography
was required for the purification of the products.
4.11. 2-Aminophenyl 2-chlorobenzyl ether (1j)
4.3. 4-Methylphenyl 3-aminobenzyl ether (1b)
Yellowish oil.13f 1H NMR (CDCl3, 300 MHz)
7.42e7.38 (m, 1H), 7.30e7.26 (m, 2H), 6.88e6.68 (m, 4H), 5.19 (s,
2H), 3.85 (s, 2H); 13C NMR (CDCl3, 100 MHz)
146.1, 136.6, 134.8,
d 7.58e7.51 (m, 1H),
Yellowish oil. IR (KBr) v 3304, 1607, 1510, 1239 cmꢀ1
(CDCl3, 400 MHz) 7.15e7.05 (m, 3H), 6.87e6.76 (m, 5H), 4.95 (s,
2H), 3.67 (s, 2H), 2.28 (s, 3H); 13C NMR (CDCl3, 100 MHz)
156.7,
;
1H NMR
d
d
132.8, 129.4, 129.0, 128.9, 126.9, 121.8, 118.4, 115.3, 112.3, 67.7.
d
146.6, 138.5, 130.0 (2C), 129.9, 129.5, 117.5, 114.7 (2C), 114.6, 113.9,
70.0, 20.5. HRMS (ESI-TOF) (m/z): calcd for C14H15NO, [MþH]þ:
214.1226, found: 214.1227.
4.12. Benzyl 4-aminobenzyl ether (1k)
Yellowish oil.13g 1H NMR (CDCl3, 400 MHz)
7.15e7.14 (m, 2H), 6.65e6.64 (m, 2H), 4.50 (s, 2H), 4.40 (s, 2H), 3.65
(s, 2H); 13C NMR (CDCl3, 100 MHz)
145.4, 138.3, 129.4, 129.1 (2C),
d 7.36e7.24 (m, 5H),
4.4. 4-Methylphenyl 2-aminobenzyl ether (1c)
d
128.1 (2C), 127.6 (2C), 127.3 (2C), 115.1, 71.8, 71.4.
Yellowish oil. IR (KBr) v 3395, 1616, 1484, 1277 cmꢀ1
(CDCl3, 400 MHz) 7.19e7.07 (m, 4H), 6.95e6.86 (m, 2H),
6.80e6.70 (m, 2H), 5.00 (s, 2H), 4.09 (s, 2H), 2.29 (s, 3H); 13C NMR
(CDCl3, 100 MHz) 156.2, 145.8, 130.2, 129.8 (3C), 129.4, 121.2, 118.2,
.
1H NMR
d
4.13. Di(4-aminobenzyl) ether (1l)
d
Yellowish solid, mp 189e190 ꢁC (lit.5c mp 189e190 ꢁC); 1H NMR
116.0, 114.6 (2C), 69.1, 20.3. HRMS (ESI-TOF) (m/z): calcd for
(CDCl3, 400 MHz)
d
7.13 (d, 4H, J¼12.0 Hz), 6.65 (d, 4H, J¼12.4 Hz),
C
14H15NO, [MþH]þ: 214.1226, found: 214.1228.
4.39 (s, 4H), 3.65 (s, 4H); 13C NMR (CDCl3, 75 MHz)
129.5 (4C), 128.3 (2C), 114.9 (4C), 71.4 (2C).
d 145.9 (2C),
4.5. Phenyl 4-aminobenzyl ether (1d)
Yellowish oil.13a 1H NMR (CDCl3, 300 MHz)
d 7.28e7.21 (m, 4H),
4.14. Methyl 4-aminobenzyl ether (1m)
6.98e6.95 (m, 3H), 6.70e6.67 (m, 2H), 4.92 (s, 2H), 3.69 (s, 2H); 13
C
Yellowish oil.13h 1H NMR (CDCl3, 400 MHz)
d 7.12 (d, 2H,
NMR (CDCl3, 100 MHz)
d 158.9, 146.3, 129.3 (2C), 129.3 (2C), 126.6,
J¼12.0 Hz), 6.65 (d, 2H, J¼12.4 Hz), 4.33 (s, 2H), 3.65 (s, 2H), 3.33 (s,
120.6, 114.9 (2C), 114.7 (2C), 69.9.
3H); 13C NMR (CDCl3, 100 MHz)
74.6, 57.6.
d 146.0,129.4 (2C), 128.0,114.9 (2C),
4.6. Phenyl 2-aminobenzyl ether (1e)
Yellowish oil.13b 1H NMR (CDCl3, 400 MHz)
4.15. Ethyl 4-aminobenzyl ether (1n)
d
7.30e7.25 (m, 4H),
7.02e6.99 (m, 3H), 6.80e6.70 (m, 2H), 5.03 (s, 2H), 4.06 (s, 2H); 13
C
Yellowish oil. IR (KBr) v 2973, 1625, 1518, 1284 cmꢀ1 1H NMR
;
NMR (CDCl3, 100 MHz)
d 158.3, 146.1, 130.1, 129.7, 129.4 (2C), 121.1,
(CDCl3, 300 MHz)
d
7.13 (d, 2H, J¼8.91 Hz), 6.65 (d, 2H, J¼8.94 Hz),
120.1, 118.2, 116.0, 114.8 (2C), 69.0.
4.37 (s, 2H), 3.64 (s, 2H), 3.50 (q, 2H, J¼7.2 Hz), 1.21 (t, 3H,
J¼6.87 Hz); 13C NMR (CDCl3, 75 MHz)
d 145.9, 129.3 (2C), 128.4,
4.7. 1-Naphthyl 3-aminobenzyl ether (1f)
Yellowish oil.13c 1H NMR (CDCl3, 400 MHz)
114.9 (2C), 72.6, 65.1,15.2. HRMS (ESI-TOF) (m/z): calcd for C9H13NO,
[MþH]þ: 152.1070; found: 152.1075.
d
8.37e8.34 (m, 1H),
7.81e7.80 (m, 1H), 7.54e7.16 (m, 5H), 6.95e6.85 (m, 3H), 6.69e6.65
(m, 1H), 5.17 (s, 2H), 3.70 (s, 2H); 13C NMR (CDCl3, 100 MHz)
d
154.3,
4.16. Isopropanyl 4-aminobenzyl ether (1o)
146.5, 138.1, 134.3, 129.3, 127.3, 126.3, 125.7, 125.5, 125.0, 122.0,
120.2, 117.1, 114.4, 113.6, 105.0, 69.8.
Yellowish oil. IR (KBr) v 2971, 1627, 1519, 1374 cmꢀ1 1H NMR
.
(CDCl3, 300 MHz)
d
7.13 (d, 2H, J¼8.22 Hz), 6.65 (d, 2H, J¼8.25 Hz),
4.8. 4-Acetophenyl 3-aminobenzyl ether (1g)
4.38 (s, 2H), 3.64e3.69 (m, 1H), 1.18 (d, 6H, J¼6.18 Hz); 13C NMR
(CDCl3, 75 MHz) d 145.8, 129.1 (2C), 128.9, 114.9 (2C), 70.2, 69.8, 22.1
(2C). HRMS (ESI-TOF) (m/z): calcd for
188.1046; found: 188.1047.
Yellowish solid, mp 152e153 ꢁC (lit.13d mp 153e154 ꢁC). 1H NMR
C
10H15NO, [MþNa]þ:
(CDCl3, 300 MHz)
d
7.94e7.91 (m, 2H), 7.17e7.14 (m, 1H), 7.01e6.98