Ammonium Chloride → 3-Cyclohexylmorpholin-4-ol

Activated MnO2 (1.29 g, 14.8 mmol) was added to a solution of N-hydroxymorpholine (0.50 g, 4.95 mmol) in dichloromethane (25 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 cyclohexylmagnesium chloride (2.0 M in diethyl ether, 4.95 mL, 9.90 mmol) at −10° C. The reaction mixture was stirred at 0° C. for 0.5 h and then saturated aqueous ammonium chloride solution (25 mL) and dichloromethane (25 mL) were added. The aqueous phase was separated and extracted with dichloromethane (2×30 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 50% diethyl ether in hexanes to give the title compound (0.220 g, 24%) as a white crystalline solid.