At room temperature, TEA (30.4 g, 300.0 mmol) was added dropwise to a mixed solution of nortropinone hydrochloride (16.2 g, 100.0 mmol) and DCM (300 mL), while maintaining the system temperature below 30 °C. After the addition was complete, (Boc)₂O (24.0 g, 110.0 mmol) was added in portions to the reaction system. The reaction system was then stirred at room temperature for 6 h. TLC showed that the reaction of the starting materials was complete. The reaction solution was washed once with 1 M dilute hydrochloric acid, saturated Na₂CO₃ aqueous solution, and saturated brine. The organic phase was dried over anhydrous Na₂SO₄ and concentrated under reduced pressure to give 22.1 g (yield: 98%) of the target compound as a colorless oil.
