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温度

0 °C

(R)-(9H-fluoren-9-yl)methyl 3-(chlorocarbonyl)piperidine-1-carboxylate (4.21 g, 11.4 mmol, prepared using W from (R)-1-(((9H-fluoren-9-yl)methoxy)carbonyl)piperidine-3-carboxylic acid [Fluka]) was dissolved in a mixture of THF and MeCN (1:1, 16 mL) and added to a solution of trimethylsilyldiazomethane (2 M in Et2O, 22.8 mL, 45.5 mmol) and THF/MeCN (1:1, 16 mL) at about 0° C. The resulting mixture was stirred at about 0° C. for about 4 h followed by the drop-wise addition of HBr (48% aqueous solution, 6.2 mL, 114 mmol). The organic solvents were removed and the precipitate was collected by filtration and dried in air to give (R)-(9H-fluoren-9-yl)methyl 3-(2-bromoacetyl)piperidine-1-carboxylate (4.46 g, 92%): LC/MS (Table 2, Method a) Rt=2.59 min; MS m/z: 428/430 (M+H)+.

1. customThe organic solvents were removed
2. filtrationthe precipitate was collected by filtration
3. customdried in air