1147557-97-8

1181816-12-5

1147557-97-8

Step 8: Synthesis of tert-butyl 6-oxo-2-azaspiro[3.3]heptane-2-carboxylate At 0 °C and under nitrogen protection, tert-butyl 6-oxo-2-azaspiro[3.3]heptane-2-carboxylate (507 mg, 2.4 mmol) was dissolved in methanol (5.0 mL) and sodium borohydride (182 mg, 4.8 mmol) was added slowly. The reaction mixture was stirred at 0 °C for 30 min. After completion of the reaction, the solvent was concentrated in vacuum by rotary evaporator to give the crude product. Saturated sodium bicarbonate solution (30 mL) was added to the crude product and the aqueous phase was extracted with dichloromethane (4 x 30 mL). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated in vacuum to afford tert-butyl 6-hydroxy-2-azaspiro[3.3]heptane-2-carboxylate (5 mg, 100% yield) as a white solid.1H NMR (300 MHz, CDCl3): δ 4.18 (m, 1H), 3.88 (d, 4H), 2.53 (m, 2H), 2.08 (m. 2H), 1.42 (s, 9H).