General Steps:
B: Synthesis of tert-butyl (R)-3-methanesulfonyloxypiperidine-1-carboxylate
Methylsulfonyl chloride (1.73 ml, 22.5 mmol) was slowly added to a stirred solution of (R)-1-Boc-3-hydroxypiperidine (3.0 g, 15 mmol) and triethylamine (3.12 ml, 22.5 mmol) in methylene chloride (30 ml) in an ice bath (0-4 °C). After addition, stirring was continued at this temperature for 30 minutes, followed by slow warming to room temperature. After stirring for 2 hours at room temperature, aqueous sodium bicarbonate solution (50 ml) was added and stirred vigorously for 30 minutes. The reaction mixture was diluted with dichloromethane (300 ml) and aqueous sodium bicarbonate (300 ml), after partitioning, the organic phase was washed with water (200 ml), dried over magnesium sulfate, and concentrated to dryness under reduced pressure to give (R)-tert-butyl 3-methanesulfonyloxypiperidine-1-carboxylate as a semi-crystalline solid.
24B: Synthesis of tert-butyl (R)-3-methanesulfonyloxypiperidine-1-carboxylate
A dichloromethane (30 ml) solution of methanesulfonyl chloride (3.73 ml, 48.45 mmol) was slowly added dropwise at 0°C to a dichloromethane (70 ml) solution of (R)-1-Boc-3-hydroxypiperidine (6.51 g, 32.3 mmol) and triethylamine (6.8 ml, 48.45 mmol). After the dropwise addition, the reaction was stirred at 0°C for 2 hours. Saturated aqueous sodium bicarbonate solution (100 ml) was added slowly, partitioned, the organic phase was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure to give tert-butyl (R)-3-methanesulfonyloxypiperidine-1-carboxylate 9.03 g (100% yield).
NMR (CDCl3, δ ppm): 4.73 (1H, m), 3.63 (2H, m), 3.44 (1H, m), 3.32 (1H, m), 3.05 (3H, s), 1.95 (2H, m), 1.83 (1H, m), 1.54 (1H, m), 1.46 (9H, s).
