4174
D.-W. Tan et al. / Tetrahedron 72 (2016) 4169e4176
2H). 13C NMR (100 MHz, DMSO-d6, ppm):
d
45.9, 55.0, 112.3, 113.6,
ppm): d 39.9, 106.8, 110.3, 112.3, 116.0, 128.8, 141.8, 148.3, 153.4.
115.7, 128.4, 128.7, 132.0, 148.7, 158.0. HRMS m/z calcd for C14H16NO
HRMS m/z calcd for C11H12NO [MþH]þ 174.0841, found 174.0922.
[MþH]þ 214.1154, found 214.1236.
4.2.12. 4-Methyl-N-(4-methylbenzyl)aniline (3l). White solid. Mp
4.2.4. N-(3-Methoxybenzyl)aniline (3d). Yellow solid. Mp 62e63 ꢀC.
55e56 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d 2.14 (s, 3H), 2.29 (s,
1H NMR (400 MHz, DMSO-d6, ppm):
d
3.73 (s, 3H), 4.26 (d, J¼4.0 Hz,
3H), 4.20 (d, J¼8.0 Hz, 2H), 5.97 (t, J¼8.0 Hz, 1H), 6.50 (d, J¼8.0 Hz,
2H), 6.23 (t, J¼8.0 Hz, 1H), 6.53 (t, J¼8.0 Hz, 1H), 6.23 (t, J¼8.0 Hz,
1H), 6.80 (t, J¼8.0 Hz, 2H), 6.96 (s, 2H), 7.05 (t, J¼8.0 Hz, 2H), 7.24 (t,
2H), 6.86 (d, J¼8.0 Hz, 2H), 7.13 (d, J¼8.0 Hz, 2H), 7.25 (d, J¼8.0 Hz,
2H). 13C NMR (100 MHz, DMSO-d6, ppm):
d 20.0, 20.6, 46.5, 112.4,
J¼8.0 Hz, 1H). 13C NMR (100 MHz, DMSO-d6, ppm):
d
46.4, 54.9,
123.9, 127.1, 128.7, 129.2, 135.4, 137.3, 146.4. HRMS m/z calcd for
111.8, 112.3,112.8,115.8, 119.3,128.8,129.3,142.1,148.7,159.4. HRMS
C
15H18N [MþH]þ 212.1361, found 212.1435.
m/z calcd for C14H16NO [MþH]þ 214.1154, found 214.1231.
4.2.13. 2,3-Dimethyl-N-(4-methylbenzyl)aniline (3m). White solid.
Mp 57e58 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
2.11 (s, 3H),
4.2.5. N-(2-Methoxybenzyl)aniline (3e). White solid. Mp 72e73 ꢀC.
d
1H NMR (400 MHz, DMSO-d6, ppm):
d
3.38 (s, 3H), 4.22 (d, J¼8.0 Hz,
2.23 (s, 3H), 2.30 (s, 3H), 4.34 (d, J¼4.0 Hz, 2H), 5.52 (t, J¼8.0 Hz,
1H), 6.30 (d, J¼8.0 Hz, 1H), 6.44 (d, J¼8.0 Hz, 1H), 6.81 (t, J¼8.0 Hz,
1H), 7.14 (d, J¼4.0 Hz, 2H), 7.28 (d, J¼8.0 Hz, 2H). 13C NMR
2H), 6.03 (t, J¼8.0 Hz, 1H), 6.52 (m, J¼8.0 Hz, 3H), 6.87 (t, J¼8.0 Hz,
1H), 6.99 (d, J¼8.0 Hz, 1H), 7.03 (t, J¼8.0 Hz, 2H), 7.21 (d, J¼8.0 Hz,
1H), 7.25 (d, J¼8.0 Hz, 1H). 13C NMR (100 MHz, DMSO-d6, ppm):
(100 MHz, DMSO-d6, ppm):
d 12.7, 20.4, 20.6, 46.5, 108.1, 118.0,
d
41.2, 55.3, 110.4, 112.1, 115.6, 120.1, 127.4, 127.7, 128.8, 148.8, 156.9.
119.9, 125.6, 126.8, 128.8, 135.3, 135.5, 137.5, 146.1. HRMS m/z calcd
HRMS m/z calcd for C14H16NO [MþH]þ 214.1154, found 214.1237.
for C16H20N [MþH]þ 226.1518, found 226.1597.
4.2.6. N-(Naphthalen-1-ylmethyl)aniline (3f). White solid. Mp
4.2.14. 4-Methoxy-N-(4-methylbenzyl)aniline (3n). White solid. Mp
66e67 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d
4.74 (d, J¼8.0 Hz,
76e78 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d 2.29 (s, 3H), 3.63
2H), 6.26 (t, J¼8.0 Hz, 1H), 6.57 (t, J¼8.0 Hz, 1H), 6.69 (d, J¼8.0 Hz,
2H), 7.10 (t, J¼8.0 Hz, 2H), 7.48 (t, J¼8.0 Hz, 1H), 7.60 (m, J¼8.0 Hz,
3H), 7.87 (d, J¼8.0 Hz, 1H), 7.99 (d, J¼8.0 Hz, 1H), 8.19 (d, J¼8.0 Hz,
(s, 3H), 4.18 (d, J¼8.0 Hz,1H), 5.77 (t, J¼8.0 Hz,1H), 6.54 (d, J¼8.0 Hz,
2H), 6.69 (d, J¼8.0 Hz, 2H), 7.14 (d, J¼4.0 Hz, 2H), 7.26 (d, J¼8.0 Hz,
2H). 13C NMR (100 MHz, DMSO-d6, ppm):
d 20.6, 47.0, 55.2, 113.3,
1H). 13C NMR (100 MHz, DMSO-d6, ppm):
d
44.6, 112.1, 115.7, 123.6,
114.5, 127.2, 128.7, 135.4, 137.4, 142.9, 150.6. HRMS m/z calcd for
125.0, 125.4, 125.7, 126.0, 127.3, 128.5, 128.9, 131.2, 133.4, 135.0,
148.9. HRMS m/z calcd for C17H16N [MþH]þ 234.1205, found
234.1279.
C
15H18NO [MþH]þ 228.1310, found 228.1387.
4.2.15. 4-Bromo-N-(4-methylbenzyl)aniline (3o). White solid. Mp
78e79 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
2.29 (s, 3H), 4.22
d
4.2.7. N-(Benzo[1,3]dioxol-5-ylmethyl)aniline (3g). White solid. Mp
(d, J¼8.0 Hz, 2H), 6.45 (t, J¼8.0 Hz, 1H), 6.54 (d, J¼8.0 Hz, 2H), 7.15
77e79 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d
4.16 (d, J¼8.0 Hz,
(d, J¼8.0 Hz, 2H), 7.18 (d, J¼8.0 Hz, 2H), 7.24 (d, J¼8.0 Hz, 2H). 13
C
2H), 5.96 (s, 2H), 6.15 (t, J¼8.0 Hz, 1H), 6.50 (t, J¼8.0 Hz, 1H), 6.56 (d,
NMR (100 MHz, DMSO-d6, ppm): d 20.6, 46.1, 106.2, 114.2, 127.1
J¼8.0 Hz, 2H), 6.83 (s, 2H), 6.91 (s, 1H), 7.03 (t, J¼8.0 Hz, 2H). 13
C
128.9, 131.3, 135.7, 136.6, 147.9. HRMS m/z calcd for C14H15BrN
NMR (100 MHz, DMSO-d6, ppm):
d 46.1, 100.7, 107.6, 108.0, 112.3,
[MþH]þ 276.0310, found 276.0384.
115.7, 120.2, 128.8, 134.2, 145.9, 147.3, 148.5. HRMS m/z calcd for
C
14H14NO2 [MþH]þ 228.0946, found 228.1029.
4.3. The procedure of two-step route
4.2.8. N-(4-Chlorobenzyl)aniline (3h). White solid. Mp 78e80 ꢀC.
1H NMR (400 MHz, DMSO-d6, ppm):
Step 1: A mixture of aryl alcohol (3.0 mmol), nitrobenzene
(1.0 mmol), RuCl3$3H2O (3.0 mol %) and K2CO3 (1.0 mmol) was stirred
at 130 ꢀC for 24 h in a sealed tube under a nitrogen atmosphere. After
cooling to room temperature, water (10 mL) was added and the
aqueous solution was extracted with dichloromethane (3ꢁ10 mL).
The combined extracts were dried with anhydrous Na2SO4, the sol-
vent was removed and the crude product was purified by a short flash
chromatography column. Step 2: A mixture of imine (0.5 mmol),
RuCl3$3H2O (3.0 mol %), K2CO3 (0.5 mmol) and glycerol (5.0 mmol)
was stirred at 130 ꢀC for 24 h in a sealed tube under a nitrogen at-
mosphere. Workup and purification was as the same as Step 1.
d
4.30 (d, J¼8.0 Hz, 2H), 6.31 (t,
J¼8.0 Hz, 1H), 6.55 (d, J¼8.0 Hz, 1H), 6.59 (t, J¼8.0 Hz, 2H), 7.08 (t,
J¼8.0 Hz, 2H), 7.41 (s, 4H). 13C NMR (100 MHz, DMSO-d6, ppm):
d
45.7, 112.3, 115.9, 128.2, 128.8, 128.9, 131.1, 139.4, 148.4. HRMS m/z
calcd for C13H13ClN [MþH]þ 218.0658, found 218.0734.
4.2.9. N-(4-(Trifluoromethyl)benzyl)aniline (3i). Yellow solid. Mp
79e80 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d
4.38 (d, J¼8.0 Hz,
2H), 6.39 (t, J¼8.0 Hz, 1H), 6.53 (t, J¼8.0 Hz, 1H), 6.57 (d, J¼8.0 Hz,
2H), 7.05 (t, J¼8.0 Hz, 2H), 7.57 (d, J¼8.0 Hz, 2H), 7.67 (d, J¼8.0 Hz,
2H). 13C NMR (100 MHz, DMSO-d6, ppm):
d 46.0, 112.3, 116.0, 123.0,
125.2,125.7,127.7,128.9,145.5,148.3. HRMS m/z calcd for C14H13F3N
4.3.1. N-Benzylideneaniline (4a). White solid. Mp 55e56 ꢀC. 1H
[MþH]þ 252.0922, found 252.0995.
NMR (400 MHz, DMSO-d6, ppm):
d
7.26 (t, J¼8.0 Hz, 3H), 7.42 (t,
J¼8.0 Hz, 2H), 7.53 (s, 3H), 7.96 (d, J¼4.0 Hz, 2H), 8.61 (s, 1H). 13
C
4.2.10. N-(Pyridin-3-ylmethyl)aniline(3j). White solid. Mp 43e45 ꢀC.
NMR (150 MHz, DMSO-d6, ppm): d 121.4, 126.4, 129.1, 129.2, 129.6,
1H NMR (400 MHz, DMSO-d6, ppm):
d
4.29 (d, J¼8.0 Hz, 2H), 6.27
131.9, 136.5, 151.9, 161.1. HRMS m/z calcd for C13H12N [MþH]þ
(t, J¼8.0 Hz, 1H), 6.52 (t, J¼8.0 Hz, 1H), 6.58 (d, J¼8.0 Hz, 2H), 7.04
(t, J¼8.0 Hz, 2H), 7.34 (m, J¼8.0 Hz, 1H), 7.74 (d, J¼8.0 Hz, 1H), 8.44
(d, J¼8.0 Hz, 1H), 8.58 (s, 1H). 13C NMR (100 MHz, DMSO-d6, ppm):
182.0892, found 182.0968.
4.3.2. N-Phenyl-1-(p-tolyl)methanimine (4b). White solid. Mp
d
44.4,112.8,116.5,123.9,129.3,135.5,136.1,148.4,148.8,149.3. HRMS
62e63 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d 2.38 (s, 3H), 7.24(d,
calcd for C12H13N2 [MþH]þ 185.1001, found 185.1076.
J¼8.0 Hz, 3H), 7.33 (d, J¼8.0 Hz, 2H), 7.41 (t, J¼8.0 Hz, 2H), 7.81 (d,
J¼8.0 Hz, 2H), 8.56 (s, 1H). 13C NMR (100 MHz, DMSO-d6, ppm):
4.2.11. N-(Furan-2-ylmethyl)aniline (3k). Light yellow oil. 1H NMR
d 21.2, 120.9, 125.8, 128.7, 129.2, 129.4, 133.5, 141.5, 151.6, 160.5.
(400 MHz, DMSO-d6, ppm):
d
4.24 (d, J¼8.0 Hz, 2H), 6.06 (t, J¼8.0 Hz,
HRMS m/z calcd for C14H14N [MþH]þ 196.1048, found 196.1123.
1H), 6.29 (s, 1H), 6.38 (s, 1H), 6.56 (t, J¼8.0 Hz,1H), 6.66 (d, J¼8.0 Hz,
2H), 7.08 (t, J¼8.0 Hz, 2H), 7.57 (s,1H). 13C NMR (100 MHz, DMSO-d6,
4.3.3. 1-(4-Methoxyphenyl)-N-phenylmethanimine (4c). White solid.
Mp 66e68 ꢀC. 1H NMR (400 MHz, DMSO-d6, ppm):
d 3.84 (s, 3H),