PAPER
Reductive N-Alkylation via Borane Reduction of Imines
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1H NMR (CDCl3): d = 3.58 (s, 4 H), 3.61 (s, 2 H), 3.78 (s, 3 H), 6.82
(d, J = 8.1 Hz, 1 H), 6.95 (t, J = 7.5 Hz, 1 H), 7.15–7.22 (m, 3 H),
7.26–7.31 (m, 4 H), 7.41 (d, J = 7.2 Hz, 4 H), 7.60 (d, J = 7.5 Hz, 1
H).
1H NMR (CDCl3): d = 0.67–0.80 (m, 2 H), 1.01–1.26 (m, 3 H),
1.50–1.68 (m, 4 H), 1.81–1.86 (m, 2 H), 2.18 (d, J = 6.9 Hz, 2 H),
3.50 (s, 4 H), 7.17–7.23 (m, 2 H), 7.26–7.31 (m, 4 H), 7.36 (d,
J = 6.9 Hz, 4 H).
13C NMR (CDCl3): d = 51.3, 55.2, 58.3, 110.1, 120.4, 126.6, 127.4,
127.6, 128.0, 128.5, 129.5, 139.9, 157.5.
13C NMR (CDCl3): d = 26.3, 26.9, 31.7, 35.8, 58.8, 60.8, 126.5,
128.0, 128.6, 140.0.
HRMS (FAB+): m/z [M + H]+ calcd for C22H24NO: 318.1858;
found: 318.1853.
N,N-Dibenzyl-N-propylamine (4am)16
Yield: 88%; light-yellow oil.
N,N-Dibenzyl-N-(3-methoxybenzyl)amine (4ah)
Yield: 95%; colorless oil.
IR (neat): 3061, 3026, 2932, 2872, 2795, 1601, 1493, 1452, 1366,
743, 696 cm–1.
IR (ATR): 3060, 3026, 2931, 2792, 1601, 1585, 1487, 1452, 1365,
1261, 1049, 739, 694 cm–1.
1H NMR (CDCl3): d = 3.53 (s, 2 H), 3.55 (s, 4 H), 3.80 (s, 3 H),
6.74–6.78 (m, 1 H), 6.96–6.99 (m, 2 H), 7.18–7.23 (m, 3 H), 7.27–
7.32 (m, 4 H), 7.39 (d, J = 6.9 Hz, 4 H).
1H NMR (CDCl3): d = 0.84 (t, J = 7.2 Hz, 3 H), 1.52 (sext, J = 7.2
Hz, 2 H), 2.36 (t, J = 7.2 Hz, 2 H), 3.53 (s, 4 H), 7.15–7.22 (m, 2 H),
7.25–7.30 (m, 4 H), 7.35 (d, J = 6.9 Hz, 4 H).
13C NMR (CDCl3): d = 11.9, 20.3, 55.4, 58.3, 126.6, 128.0, 128.6,
139.9.
13C NMR (CDCl3): d = 55.2, 57.9, 58.0, 112.0, 114.2, 121.0, 126.7,
N,N-Dibenzyl-N-(1-methylethyl)amine (4an)17
Yield: 35%; light-yellow oil.
128.1, 128.6, 129.0, 139.5, 141.3, 159.5.
HRMS (FAB+): m/z [M + H]+ calcd for C22H24NO: 318.1858;
found: 318.1871.
IR (ATR): 3064, 3024, 2962, 2929, 2827, 2794, 1601, 1493, 1452,
1362, 741, 723, 694 cm–1.
N,N-Dibenzyl-N-(2,4,6-trimethoxybenzyl)amine (4ai)
Yield: 73%; white solid; mp 84–86 °C.
1H NMR (CDCl3): d = 1.05 (d, J = 6.6 Hz, 6 H), 2.92 (hept, J = 6.6
Hz, 1 H), 3.55 (s, 4 H), 7.16–7.21 (m, 2 H), 7.25–7.30 (m, 4 H), 7.37
(d, J = 6.9 Hz, 4 H).
13C NMR (CDCl3): d = 17.6, 48.1, 53.2, 126.4, 128.0, 128.3, 140.9.
IR (ATR): 3060, 3022, 2997, 2939, 2833, 2804, 2787, 1604, 1593,
1495, 1460, 1452, 1415, 1367, 742, 694 cm–1.
1H NMR (CDCl3): d = 3.53 (s, 4 H), 3.60 (s, 2 H), 3.74 (s, 6 H), 3.79
(s, 3 H), 6.09 (s, 2 H), 7.13–7.18 (m, 2 H), 7.23–7.27 (m, 4 H), 7.38
(d, J = 6.9 Hz, 4 H).
N-Cyclohexyl-N,N-dibenzylamine (4ao)18
Yield: 31%; pale-yellow solid; mp 57–58 °C.
IR (ATR): 3064, 3022, 2927, 2852, 2829, 2802, 1603, 1491, 1450,
1375, 741, 731, 696 cm–1.
1H NMR (CDCl3): d = 1.01–1.19 (m, 3 H), 1.25–1.36 (m, 2 H),
1.53–1.59 (m, 1 H), 1.75 (d, J = 11.4 Hz, 2 H), 1.88 (d, J = 12.6 Hz,
2 H), 2.46 (tt, J = 3.3, 11.4 Hz, 1 H), 3.62 (s, 4 H), 7.15–7.20 (m, 2
H), 7.24–7.28 (m, 4 H), 7.36 (d, J = 7.2 Hz, 4 H).
13C NMR (CDCl3): d = 45.6, 55.3, 55.5, 57.9, 90.4, 108.1, 126.2,
127.6, 128.6, 141.0, 160.1, 160.2.
HRMS (FAB+): m/z [M + H]+ calcd for C24H28NO3: 378.2069;
found: 378.2058.
N-(4-Acetylbenzyl)-N,N-dibenzylamine (4aj)
Yield: 82%; yellow oil.
13C NMR (CDCl3): d = 26.2, 26.6, 28.7, 53.8, 57.6, 126.4, 127.9,
128.3, 141.1.
IR (ATR): 3060, 3028, 2922, 2796, 1680, 1606, 1493, 1452, 1412,
1356, 1265, 742, 696 cm–1.
1H NMR (CDCl3): d = 2.57 (s, 3 H), 3.55 (s, 4 H), 3.59 (s, 2 H),
7.19–7.25 (m, 2 H), 7.28–7.33 (m, 4 H), 7.38 (d, J = 7.2 Hz, 4 H),
7.49 (d, J = 8.4 Hz, 2 H), 7.90 (d, J = 8.4 Hz, 2 H).
13C NMR (CDCl3): d = 26.7, 57.6, 58.1, 126.9, 128.2, 128.3, 128.6,
128.6, 135.9, 139.1, 145.5, 197.6.
N-Benzyl-N-methyl-N-(4-nitrobenzyl)amine (4bc)19
Yield: 91%; light-yellow oil.
IR (neat): 3061, 3028, 2945, 2845, 2789, 1601, 1520, 1495, 1454,
1344, 843, 739, 698 cm–1.
1H NMR (CDCl3): d = 2.19 (s, 3 H), 3.55 (s, 2 H), 3.58 (s, 2 H),
7.22–7.37 (m, 5 H), 7.53 (d, J = 8.7 Hz, 2 H), 8.16 (d, J = 8.7 Hz, 2
HRMS (FAB+): m/z [M + H]+ calcd for C23H24NO: 330.1858;
found: 330.1877.
H).
13C NMR (CDCl3): d = 42.4, 60.9, 62.1, 123.4, 127.1, 128.2, 128.7,
129.1, 138.5, 146.9, 147.3.
N,N-Dibenzyl-N-(2-pyridylmethyl)amine (4ak)14
Yield: 69%; colorless oil.
N-Benzyl-N-cyclohexyl-N-methylamine (4bo)13
Yield: 47%; light-yellow oil.
IR (neat): 3061, 3026, 2924, 2799, 1589, 1570, 1495, 1474, 1454,
1433, 1367, 735, 698 cm–1.
1H NMR (CDCl3): d = 3.61 (s, 4 H), 3.74 (s, 2 H), 7.08–7.12 (m, 1
H), 7.19–7.24 (m, 2 H), 7.28–7.33 (m, 4 H), 7.40 (d, J = 7.2 Hz, 4
H), 7.60–7.67 (m, 2 H), 8.48 (d, J = 5.1 Hz, 1 H).
13C NMR (CDCl3): d = 58.2, 59.8, 121.7, 122.5, 126.8, 128.1, 128.6,
136.3, 139.1, 148.6, 160.0.
IR (ATR): 3062, 3026, 2925, 2852, 2783, 1603, 1495, 1450, 1360,
733, 696 cm–1.
1H NMR (CDCl3): d = 1.04–1.36 (m, 5 H), 1.63 (d, J = 11.7 Hz, 1
H), 1.78–1.90 (m, 4 H), 2.19 (s, 3 H), 2.39–2.48 (m, 1 H), 3.56 (s, 2
H), 7.18–7.32 (m, 5 H).
13C NMR (CDCl3): d = 26.1, 26.5, 28.7, 37.7, 57.8, 62.5, 126.5,
128.0, 128.7, 140.2.
N,N-Dibenzyl-N-cyclohexylmethylamine (4al)15
Yield: 98%; white solid; mp 56–60 °C.
N-Benzyl-N-(4-nitrobenzyl)-N-phenylamine (4cc)
Yield: 81%; yellow solid; mp 145–147 °C.
IR (KBr): 3063, 3022, 2916, 2843, 2789, 1601, 1493, 1447, 1366,
743, 735, 698 cm–1.
IR (ATR): 3082, 3060, 3030, 2931, 2862, 1597, 1506, 1491, 1450,
1342, 843, 727, 690 cm–1.
Synthesis 2010, No. 1, 36–42 © Thieme Stuttgart · New York