General procedure for the synthesis of tert-butyl 2-hydroxymethyl-azetidine-1-carboxylate from N-Boc-azetidine-2-carboxylic acid: to a solution of N-Boc-azetidine-2-carboxylic acid (1.45 g, 7.21 mmol) in anhydrous THF (12 mL) was added slowly and dropwise borane-methyl sulfide complex (10 M, 3 mL) at 0 °C. The reaction mixture was gradually warmed to room temperature and stirred for 3 hours. Upon completion of the reaction, the reaction was quenched with methanol (10 mL) followed by dilution of the reaction mixture with dichloromethane (100 mL). The organic phase was washed with water (40 mL x 3), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford tert-butyl 2-hydroxymethyl-azetidine-1-carboxylate (1.25 g) as a colorless oil.MS-ESI (m/z): 132.0 [M+1-56]+.
