Synthesis
General procedure: synthesis of Intermediate 153: tert-butyl N-(benzyloxy)carbamate. To a solution of O-benzylhydroxylamine hydrochloride (225 g, 1.44 mol) in dichloromethane (300 mL) was added an aqueous sodium bicarbonate solution (261 g, 3.11 mol, 300 ml). After 1 hour of reaction, di-tert-butyl dicarbonate (375 g, 1.72 mol) was slowly added at 0°C. The reaction mixture was stirred in a water/ice bath at 0 °C for 60 min, followed by continued stirring for 16 h at room temperature. Upon completion of the reaction, the reaction was quenched by addition of 300 mL of aqueous sodium bicarbonate. The aqueous phase was separated and extracted with dichloromethane (3 x 500 mL), the organic layers were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure. Purification by silica gel fast column chromatography (eluent: petroleum ether/ethyl acetate=10:1) afforded 220 g (69% yield) of the target compound, tert-butyl N-(benzyloxy)carbamate, as a yellow oil.1H NMR (300 MHz, CDCl3) δ: 1.43 (9H,s), 4.85 (2H,s), 7.19-7.21 (1H brs), 7.30-7.40 (5H, m).
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