GENERAL METHOD: BOC-L-proline (1.00 g, 4.65 mmol), di-tert-butyl dicarbonate (1.52 g, 6.97 mmol), ammonium bicarbonate (0.55 g, 6.97 mmol), and pyridine (1.0 mL) were dissolved in dioxane (20 mL), and the reaction was stirred at room temperature for 6 hours. After completion of the reaction, the product was extracted with dichloromethane, the organic phase was washed sequentially with 1 M hydrochloric acid and saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. To the concentrate was added n-hexane (100 mL) and sonication prompted the product to precipitate as a white solid to afford N-tert-butoxycarbonyl-L-prolinamide (0.85 g, 85% yield). The product was characterized by 1H NMR (300 MHz, CDCl3): δ 4.37-4.34 (m, 1H), 3.47-3.36 (m, 2H), 2.07-1.85 (m, 4H), 1.49 (s, 9H). Mass spectrum (ESI) m/z 215 [M + H]+.
