Synthesis
General procedure for the synthesis of N-Boc-(2S,3S)-(2S,3S)-3-hydroxy-2-carboxypyrrolidine from (2S,3S)-1-(tert-butoxycarbonyl)-3-hydroxy-pyrrolidine-2-carboxylic acid methyl ester: to 1-(tert-butoxycarbonyl)-2-methyl-(2S,3S)-3-hydroxypyrrolidine-1,2-dicarboxylate (0.30 g, 1.22 mmol) in a tetrahydrofuran (12 mL) solution was added to 0.2N aqueous lithium hydroxide (6.12 mL, 1.22 mmol). The reaction mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction mixture was diluted with ether (30 mL) and extracted with 0.2N aqueous lithium hydroxide solution (3 x 5 mL). The aqueous layers were combined and acidified with 5% aqueous hydrochloric acid to pH=2. The acidic aqueous layer was extracted with ethyl acetate (3 x 30 mL). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated in vacuum to afford N-Boc-(2S,3S)-3-hydroxy-2-carboxypyrrolidine as a gel (0.25 g, 88% yield), which was used directly in the next reaction. Mass spectrum (ES+) m/z 230.3 (M+1).
