GENERAL STEPS: A solution of DMF (100 mL) containing N-Boc-(2S,3S)-3-hydroxy-2-carboxypyrrolidine (37.16 g, 71 mmol) was cooled to 0°C. To this solution was added K2CO3 (16 g, 116 mmol) followed by slow dropwise addition of iodomethane (5.4 mL, 87 mmol). The reaction mixture was gradually warmed to room temperature over a period of 1 h. It was observed that the solution changed to a yellow non-homogeneous mixture. Next, the mixture was heated at 90 °C for 1 h, after which it was cooled to room temperature. After completion of the reaction, the reaction solution was diluted with saturated brine and extracted with ether. The organic phases were combined, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure to afford the target product (2S,3S)-1-(tert-butoxycarbonyl)-3-hydroxy-pyrrolidine-2-carboxylic acid methyl ester (14.8 g, 87% yield) as a yellow oil.
