2-(3,4-dimethoxyphenyl)-N-(4-nitrobenzylidene)ethanamine

¹H-NMR (200 MHz; CDCl₃): δ 8.30 (d, J = 8.8 Hz, 2H), 8.23 (s, 1H), 7.93-7.88 (m, 2H), 6.86-6.77 (m, 3H), 3.95 (td, J = 7.1, 1.1 Hz, 2H), 3.87 (d, J = 7.7 Hz, 6H), 3.03 (t, J = 7.1 Hz, 2H).

Procedure
4-Nitrobenzaldehyde (4.6 g, 30.4 mmol, 1 eq) was suspended in diethyl ether (40 mL). 3,4-dimethoxyphenethylamine (5 mL, 30.3 mmol, 1 eq) was added, dropwise, to the stirring mixture, after which the solution went a clear dark orange colour. The reaction mixture was left to stir at rt from 13:30.
At 4:30 (+3 hours), a fine yellow precipitate had formed and in the now colourless solution. The solvent was removed under reduced pressure to give crude KAB23-1 as a fine yellow powder (10.0 g, 105%).
Purification
27/03/12. A test recrystallisation from hot ethanol was performed according to the literature.^[1]Start: 779 mg. ReXST: 610 mg. Yield: 78%.
Fine yellow needles were formed. The crystals were filtered and washed with EtOH, then dried under a high vacuum.
The remainder of the sample was recrystallised from hot EtOH. The flask was left to stand at rt overnight before the crystals were filtered, then washed with EtOH and dried under a high vacuum for 6 hours. Start: 9.1 g. reXST: 7.9 g. Yield 87%.


References
[1] R. Gitto, M. L. Barreca, L. De Luca, G. De Sarro, G. Ferreri, S. Quartarone, E. Russo, A. Constanti, A. Chimirri, Journal of Medicinal Chemistry 2003, 46, 197.