R. Quevedo et al.
126.1, 63.0, 37.5. FT-IR (KBr) cm-1: 3,027, 2,929, 2,855, 1,670, 1,601. ESI-
HRMS: m/z 236.1391 ([M ? H]?, calc. 236.1434).
General procedure for the reaction between tyramine 2 and non-enolizable
aldehydes
The aldehyde (9 mol) was added to a solution of 2 (9 mol) in ethanol 96 %. The
mixture was refluxed for 24 h; subsequently, the solvent was removed at reduced
pressure. The solid obtained was recrystallized from ethanol (96 %).
N-(3-nitrobenzylidene)-2-(4-hydroxyphenyl)ethanamine 9a Orange solid. Yield
60 %. Mp = 118–121 °C. 1H NMR (400 MHz, DMSO-d6): d 8.49 (1H, t,
J = 1.8 Hz), 8.37 (1H, s), 8.27 (1H, dd, J = 8.2 Hz and 2.3 Hz), 8.11 (1H, d,
J = 7.7 Hz), 7.72 (1H, t, J = 7.9 Hz), 7.02 (2H, d, J = 8.4 Hz), 6.65 (2H, d,
J = 8.4 Hz), 3.78 (2H, t, J = 7.3 Hz), 2.82 (2H, t, J = 7.3 Hz). 13C NMR
(100 MHz, DMSO-d6): d 159.4, 155.7, 148.3, 137.8, 134.2, 130.6, 129.9, 125.1,
122.0, 115.2, 62.4, 36.0. FT-IR (KBr) cm-1: 3,087, 2,911, 1,644, 1,612. ESI-
HRMS: m/z 271.1028 ([M ? H]?, calc. 271.1077).
N-(4-hydroxy-3-methoxybenzylidene)-2-(4-hydroxyphenyl)ethanamine 9b White
solid. Yield 87 %. mp = 139–141 °C. 1H NMR (400 MHz, DMSO-d6): d 9.19 (1H,
br s), 8.14 (1H, s), 7.64 (2H, d, J = 8.8 Hz), 7.01 (2H, d, J = 8.4 Hz), 6.97 (2H, d,
J = 8.8 Hz), 6.65 (2H, d, J = 8.4 Hz), 3.78 (3H, s), 3.68 (2H, t, J = 7.4 Hz), 2.77
(2H, t, J = 7.4 Hz). 13C NMR (100 MHz, DMSO-d6): d 161.2, 160.3, 155.5, 130.1,
129.8, 129.5, 129.1, 115.1, 114.1, 62.5, 55.4, 36.3. FT-IR (KBr) cm-1: 3,012, 2,920,
2,678, 2,604, 1,649, 1,605. ESI-HRMS: m/z 272.1228 ([M ? H]?, calc. 272.1281).
1,4-bis(N-(2-(4-hydroxyphenyl)ethyl)iminomethyl)benzene 9c Light-brown solid.
Yield 94 %. mp = 168–169 °C. 1H NMR (400 MHz, DMSO-d6): d 9.21 (2H, br s),
8.25 (2H, s), 7.75 (4H, s), 7.02 (4H, d, J = 8.4 Hz), 6.65 (4H, d, J = 8.4 Hz), 3.75
(4H, t, J = 7.3 Hz), 2.80 (4H, t, J = 7.3 Hz). 13C NMR (100 MHz, DMSO-d6): d
160.7, 155.6, 137.9, 130.0, 129.8, 128.2, 115.1, 62.6, 36.1. FT-IR (KBr) cm-1
:
3,486, 3,200–2,500, 1,641. ESI-HRMS: m/z 373.1815 ([M ? H]?, calc. 373.1911).
2-(4-hydroxyphenyl)-N-((E)-3-phenylallylidene)ethanamine 9d Light-brown sol-
id. Yield 46 %. mp = 165–168 °C. 1H NMR (400 MHz, Pyridine-d5): d 11.33 (1H,
br s), 7.98 (1H, d, J = 8.7 Hz), 7.52 (2H, d, J = 7.1 Hz), 7.35–7.25 (5H, m),
7.21–7.15 (3H, m), 6.94 (1H, d, J = 16.1 Hz), 3.84 (2H, t, J = 7.3 Hz), 3.02 (2H, t,
J = 7.3 Hz). 13C NMR (100 MHz, Pyridine-d5): d 163.2, 157.7, 141.6, 136.8,
131.4, 130.9, 129.6, 129.54, 129.52, 128.0, 116.6, 64.3, 37.5. FT-IR (KBr) cm-1
:
3,200–2,200, 1,635, 1,610. ESI-HRMS: m/z 252.1331 ([M ? H]?, calc. 252.1383).
Procedure for the reaction between dopamine 3 and trans-cinnamaldehyde 7d
The aldehyde 7d (9 mol) was added to a solution of 3 (9 mol) in methanol. The
mixture was refluxed for 24 h; subsequently, the solvent was removed at reduced
pressure. The solid obtained was recrystallized from ethanol (96 %).
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