Step 3: Synthesis of (S)-5-methylmorpholin-3-one (116): compound (3) (145 g) was dissolved in dichloromethane (2000 mL) in a 5.0 L round-bottomed flask at 0 °C. Subsequently, potassium tert-butanol (430 g, 4.0 eq.) dissolved in isopropanol (1600 mL) was added drop-wise at the same temperature and the reaction mixture was stirred for 1 hour at 0 °C. Upon completion of the reaction, the pH of the reaction mixture was adjusted to 7-8 with concentrated hydrochloric acid (180-200 mL) and the temperature was maintained at 0 °C. Next, isopropanol was removed by evaporation on a rotary evaporator and extracted with dichloromethane (1000 mL x 3). The organic layers were combined, dried with anhydrous sodium sulfate and finally concentrated to give the target product (88 g, 80% yield). The analytical data of the product were as follows:'HNMR (300 MHz, CDCl3), δ 6.75 (broad peak, 1H), 4.21-4.06 (multiple peaks, 2H), 3.91-3.86 (multiple peaks, 1H), 3.71 (multiple peaks, 1H), 3.35 (multiple peaks, 1H), 1.19 (double peaks, J=6.0 Hz, 3H); ESIMS: 116 (M+1).
![Acetamide, 2-chloro-N-[(1S)-2-hydroxy-1-methylethyl]-](/CAS/20210305/GIF/94193-79-0.gif)
