610791-05-4

67-56-1

142253-55-2

610791-05-4

General procedure for the synthesis of methyl 1-(tert-butoxycarbonyl)azetidine-3-carboxylate from methanol and 1-Boc-azetidine-3-carboxylic acid: 1-(tert-butoxycarbonyl)azetidine-3-carboxylic acid (AXL016917, 1000 mg, 4.97 mmol) was dissolved in a mixture of solvents with methanol (5 mL) and toluene (20 mL), and subsequently the solution was cooled to 0°C. Trimethylsilyl diazomethane (7.45 mmol) was slowly added dropwise over a period of 15 min, during which slight bubble production was observed. The color of the solution gradually changed from clear to light yellow. The reaction mixture was continued to be stirred at 0 °C for 10 min, followed by slow warming to room temperature over a period of 30 min. Upon completion of the reaction, toluene was removed by concentration and distillation under reduced pressure to afford 1.055 g of methyl 1-(tert-butoxycarbonyl)azetidine-3-carboxylate (99% crude yield), which could be used in the next step of the reaction without further purification.