methyl (2S,3S)-3-hydroxypyrrolidine-2-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of (2S,3S)-methyl 3-hydroxypyrrolidine-2-carboxylate (16 g, 0.110 moles) in water (60 mL) was added NaNO2 (16 g, 0.220 moles) in water (30 mL) followed by the addition of glacial acetic acid (9.43 mL, 0.165 moles) at 0° C. and the reaction mixture was stirred for 4 h. Once the starting material had disappeared (monitored by TLC), the reaction mixture was diluted with ethyl acetate. The organic layer was washed with water, brine, dried over Na2SO4 and concentrated to get the title compound which was used in the next step without purification. The organic layer was washed with water, brine dried over Na2SO4 concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of trans-3-hydroxy-L-proline (15 g, 0.114 moles) in methanol (200 mL) was added borontrifluoride diethyl ether (42 mL, 0.343 moles) and the reaction mixture was refluxed for 48 h. Once the starting material had disappeared (monitored by TLC) the reaction mixture was concentrated to get the title compound which was used in the next step without further purification. the reaction mixture was refluxed for 48 h was concentrated