119844-66-5

350595-57-2

Step-4: Synthesis of (S)-3-methylmorpholine (117): lithium aluminum hydride (87 g, 3.0 eq.) was suspended in anhydrous tetrahydrofuran (1500 mL) in a three necked round bottomed flask at 0°C under nitrogen protection. (S)-5-methylmorpholin-3-one (88 g) was dissolved in anhydrous tetrahydrofuran (500 mL) and slowly added dropwise to the reaction system at the same temperature. The reaction mixture was gradually warmed to room temperature and stirred continuously overnight. Upon completion of the reaction, it was quenched sequentially with water (100 mL), 2N sodium hydroxide solution (200 mL), and water (300 mL) (using Fisher post-treatment method) and stirred for 30 minutes. Subsequently, a 2% methanol/dichloromethane mixture (1000 mL) was added and stirring was continued for 1.0 hour. The crude product was filtered through a diatomaceous earth pad, and the filtrate was dried over anhydrous sodium sulfate and finally concentrated on a rotary evaporator at a low water bath temperature of 20-25 °C to afford the target product (S)-3-methylmorpholine (55 g, 71% yield).