Synthesis
At room temperature, 2,4-dimethoxybenzaldehyde (Sigma Aldrich; 1.1 g, 6.61 mmol) was dissolved in 20 mL of tetrahydrofuran (THF). To this solution 2,4-dimethoxybenzylamine (Sigma Aldrich; 1.5 mL, 9.98 mmol) was added dropwise, followed by sodium triacetoxyborohydride (Sigma Aldrich; 17 g; 80.4 mmol). The reaction mixture gradually became turbid and the reaction was stirred overnight at room temperature. Upon completion of the reaction, the reaction mixture was diluted with saturated sodium bicarbonate (NaHCO3) solution and subsequently extracted with ethyl acetate (EtOAc). The organic phases were combined, dried with anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure. The resulting crude product was purified by silica gel column chromatography (using a 40 g ISCO column with an elution gradient of 0 to 100% ethyl acetate/hexane) to afford bis(2,4-dimethoxybenzyl)amine (2.08 g, 6.55 mmol, 99% yield, 96% purity).
References
[1] Patent: WO2017/147410, 2017, A1. Location in patent: Page/Page column 1832
[2] Tetrahedron Letters, 2010, vol. 51, # 28, p. 3645 - 3648
[3] Chemische Berichte, 1968, vol. 101, # 10, p. 3623 - 3641
[4] Patent: US2013/131050, 2013, A1. Location in patent: Paragraph 0570; 0571
[5] Patent: WO2018/97945, 2018, A1. Location in patent: Paragraph 0395
