General procedure for the synthesis of 3-(Boc-amino)-2-piperidinone from 3-aminopiperidin-2-one and di-tert-butyl dicarbonate: To a 500 mL round-bottomed flask were added 3-aminopiperidin-2-one (10 g, 87.61 mmol, 1.00 equiv), methanol (200 g, 6.24 mol, 71.25 equiv), and triethylamine (20 mL). A solution of di-tert-butyl dicarbonate (20 g, 91.64 mmol, 1.05 equiv) in methanol (100 mL) was added slowly and dropwise with stirring at 0 °C. The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the mixture was concentrated under vacuum. The crude product was purified by column chromatography to afford 16 g (85% yield) of 3-(Boc-amino)-2-piperidone as a white solid.
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