[Synthesis]
Step 9-2: Preparation of (R)-1-(tert-butoxycarbonyl)-3-dimethylaminopyrrolidine. 1.25 g of (R)-1-(tert-butoxycarbonyl)-3-dimethylaminopyrrolidine hydrochloride (chemical purity: 99.9 area %) was dissolved in a mixed system of 2.46 g of 23 wt% brine, 5.03 g of toluene, and 738 mg of 30 wt% aqueous sodium hydroxide, and the reaction mixture was stirred thoroughly. After completion of the reaction, liquid-liquid separation was carried out and the organic phase was collected. The organic phase was concentrated under reduced pressure to remove the solvent, followed by vacuum drying to afford 999 mg of (R)-1-Boc-3-(dimethylamino)pyrrolidine as a colorless transparent liquid (chemical purity: 99.5 area %, 95% yield). The structure of the product was confirmed by 1H-NMR (CDCl3): δ (ppm) 1.46 (s, 9H), 1.74 (m, 1H), 2.05 (m, 1H), 2.24 (s, 6H), 2.63 (m, 1H), 3.05 (m, 1H), 3.27 (m, 1H), 3.45-3.69 (m, 2H). |