Facile Preparation of 4‑(4-Nitrophenyl)morpholin-3-one via the Acid-Catalyzed Selective Oxidation of 4‑(4-Nitrophenyl)morpholine by Sodium Chlorite as the Sole Oxidant

4-(4-Nitrophenyl)­morpholin-3-one and 4-(4-aminophenyl) morpholin-3-one are the key intermediates for rivaroxaban synthesis. A facile and economically efficient process has been developed for the preparation of these intermediates. Excellent yield of 4-(4-nitrophenyl)­morpholine is obtained by condensing 4-chloro nitrobenzene and morpholine, and 4-(4-nitrophenyl)­morpholine is oxidized using inexpensive sodium chlorite to achieve a good yield of the corresponding 4-(4-nitrophenyl)­morpholin-3-one. Finally, the key intermediate of rivaroxaban, 4-(4-aminophenyl) morpholin-3-one, is achieved by the iron­(III)-catalyzed reduction of the nitro group with aqueous hydrazine. No high-cost materials were used, and the process did not require column purification.