Ammonium Chloride → 3-Phenylmorpholin-4-ol

Activated MnO2 (0.65 g, 7.41 mmol) was added to a solution of N-hydroxymorpholine (0.25 g, 2.47 mmol) in dichloromethane (15 mL) at 0° C. and the mixture was stirred for 1 h. The reaction mixture was filtered through a pad of Celite™ and Na2SO4. The filtrate was added dropwise to a solution of phenylmagnesium chloride (2.0 M in tetrahydrofuran, 2.47 mL, 4.94 mmol) at −10° C. The reaction mixture was stirred at 0° C. for 0.5 h and then saturated aqueous ammonium chloride solution (15 mL) and dichloromethane (15 mL) were added. The aqueous phase was separated and extracted with dichloromethane (2×20 mL). The combined organic layers were dried (Na2SO4) and concentrated under reduced pressure. The crude product was subjected to flash chromatography on SiO2 eluting with 25% diethyl ether in hexanes to give the title compound (0.045 g, 11%) as a white crystalline solid.