General steps:
1. In a dry reaction flask, (R)-1-(tert-butoxycarbonyl)piperidine-2-carboxylic acid (5.1 g, 22.2 mmol) was dissolved in DMF (60 mL).
2. K2CO3 (12.3 g, 88.8 mmol) and iodomethane (1.7 mL, 26.6 mmol) were added sequentially to the above solution.
3. The reaction mixture was stirred at room temperature overnight.
4. Upon completion of the reaction, the reaction mixture was diluted with ethyl acetate.
5. The organic layer was separated and washed 6 times with distilled water and once with saturated saline.
6. The organic layer was dried over anhydrous Na2SO4, filtered and concentrated to give methyl (R)-N-Boc-piperidine-2-carboxylate (5.4 g, 99% yield).
7. The product was characterized by 1H NMR (300 MHz, CDCl3): δ 4.82 (m, 1H), 3.99 (m, 1H), 3.75 (s, 3H), 2.95 (m, 1H), 2.21 (m, 1H), 2.45 (m, 14H).
