Spiro[piperidine-4,4'-pyrido[2,3-d][1,3]oxazin]-2'(1'H)-one hydrochloride

883984-95-0

1038866-44-2

Step 3: 16.4 g (42.4 mmol) of benzyl 7'-chloro-2'-oxo-1',2'-dihydrospiro[piperidin-4,4'-pyrido[2,3-d][1,3]oxazine]-1 -carboxylate and 2.00 g of 10% palladium/carbon (Pd/C) catalyst were placed in 500 mL of ethanol and hydrogenated at room temperature under a hydrogen atmosphere for 6 hours. Subsequently, 1.0 g of 10% palladium/carbon (Pd/C) catalyst was added additionally and the hydrogenation was continued for 3 hours at room temperature under hydrogen atmosphere. Upon completion of the reaction, the reaction mixture was filtered and the solvent was removed under vacuum. The resulting residue was ground with ethanol and the resulting precipitate was collected by diafiltration, washed with ethanol and dried. A final product of 5.40 g was obtained in a yield of 50% of the theoretical value. The product was analyzed by ESI-MS showing m/z = 220 (M + H)+ and HPLC retention time (Rt) of 0.90 min (Method C).