1,3-Dibromobenzene (50 g, 0.21 mol) and morpholine (15.89 mL, 0.19 mol) were used as raw materials, and both were added to the reaction flask with anhydrous toluene (200 mL) via a syringe under argon protection. After thorough mixing, R-BINAP (1.32 g, 0.0021 mol), palladium(0) dibenzylideneacetone (0.640 g, 0.006 mol) and DBU (25.8 mL, 0.17 mol) were added sequentially. The reaction mixture was stirred at 60 °C, followed by the addition of sodium tert-butoxide (30.55 g, 0.32 mol) and the reaction temperature was raised to 100 °C and continued overnight. Upon completion of the reaction, the suspension was diluted with ethyl acetate, filtered through diatomaceous earth and the organic phase was washed sequentially with water and brine. The organic phase was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography with the eluent ethyl acetate:hexane (1:1) to afford the target compound 4-(3-bromophenyl)morpholine as a yellow oil (36.5 g, 71% yield). Mass spectrometry (ES+) showed the molecular ion peak m/z 242 ([M+H]+).
