324769-06-4

24424-99-5

173186-91-9

324769-06-4

General procedure for the synthesis of 1-BOC-3,3-dimethyl-4-oxopiperidine from di-tert-butyl dicarbonate and 3,3-dimethyl-1-phenylmethyl-piperidin-4-one: 10.14 g (46.66 mmol) of 1-benzyl-3,3-dimethyl-4-oxo-piperidine, 1.03 g of 10% palladium-carbon catalyst and 11.09 g (50.81 mmol) of di- di-tert-butyl carbonate were dissolved in 210 mL of methanol. The mixture was purged three times with nitrogen and then three times with hydrogen. Subsequently, the mixture was subjected to 50 psig hydrogen pressure and the reaction was shaken at room temperature for 16 hours. Upon completion of the reaction, the reaction mixture was filtered through a bed of diatomaceous earth and glass microfiber filter paper. The filtrate was concentrated under reduced pressure and the residue was purified by silica gel column chromatography using hexane containing 20% ethyl acetate as eluent. The elution grade containing the target product was collected and concentrated under reduced pressure to give 9.38 g (88.5% yield) of 1-(tert-butoxycarbonyl)-3,3-dimethyl-4-oxopiperidine.