General procedure: lithium aluminum hydride (3.55 g, 93.8 mmol) was added batchwise to a stirred solution of (R)-5-phenylmorpholin-3-one (4.15 g, 23.4 mmol) in anhydrous THF (30 mL) under the protection of nitrogen, keeping the reaction temperature at 0 °C. Subsequently, the reaction mixture was slowly warmed up to 45 °C and stirred continuously at this temperature for 5 hours. Upon completion of the reaction, the reaction was carefully quenched with saturated aqueous sodium sulfate solution. Ethyl acetate was added to the aqueous phase mixture and stirring was continued for 10 minutes. The resulting suspension was filtered through diatomaceous earth and the filtrate was collected and dried with anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure and the residue was dried well to give 615 mg of the target product 3-phenylmorpholine. The product was characterized by NMR (300 MHz, CDCl3): δ 3.00 (d, J = 11.4 Hz, 1H), 3.07-3.17 (m, 1H), 3.40 (t, J = 10.5 Hz, 1H), 3.62-3.70 (m, 1H), 3.80-3.95 (m, 3H), 7.27-7.41 (m, 5H).
