Morpholine (13, 1.4 mL, 1.39 g, 16 mmol) and 4-bromobenzyl bromide (12, 1.0 g, 4 mmol) were reacted in acetonitrile (50 mL). The reaction mixture was heated to reflux for 4 hours. After completion of the reaction, water was added and extracted with dichloromethane (3 x 50 mL). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by fast column chromatography (silica gel column, 6 cm diameter, 50 mL volume, eluent n-hexane/ethyl acetate=8/2, Rf=0.19) to afford the target product 14 as a colorless solid (1.0 g, 3.9 mmol, 98% yield). The melting point of the product was 85 °C. Structural confirmation and purity analysis of the product were carried out by various analytical methods including 1H NMR, 13C NMR, IR, MS (ESI), HRMS and HPLC, which showed that the product was pure and structurally correct.
