ethyl (2R,4R)-4-hydroxypyrrolidine-2-carboxylate

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold solution of 4-hydroxy-pyrrolidine-2-carboxylic acid ethyl ester (1) (1.4 g, 7.1 mmol) and triethyl amine (0.998 mL, 7.1 mmol) in pyridine (14 mL) at −5° C. was added portion-wise 4-toluenesulfonyl chloride (3.42 g, 17.9 mmol). The cold solution was then stirred for 1 h at 0° C. and stored overnight in the refrigerator. Then the mixture was further stirred at room temperature for 5 h and poured into ice water (10 mL). The precipitate separated out was filtered, washed with water (2×5 mL), and dried to give compound (2) as a white solid. stored overnight in the refrigerator Then the mixture was further stirred at room temperature for 5 h The precipitate separated out was filtered washed with water (2×5 mL) dried

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold solution of 4-hydroxy-pyrrolidine-2-carboxylic acid ethyl ester (1) (1.4 g, 7.1 mmol) and triethyl amine (0.998 mL, 7.1 mmol) in pyridine (14 mL) at −5° C. was added portion-wise 4-toluenesulfonyl chloride (3.42 g, 17.9 mmol). The cold solution was then stirred for 1 h at 0° C. and stored overnight in the refrigerator. Then the mixture was further stirred at room temperature for 5 h and poured into ice water (10 mL). The precipitate separated out was filtered, washed with water (2×5 mL), and dried to give compound (2) as a white solid. stored overnight in the refrigerator Then the mixture was further stirred at room temperature for 5 h The precipitate separated out was filtered washed with water (2×5 mL) dried

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

Procedure: To a stirred solution of cis-4-hydroxy-pyrrolidine-2-carboxylic acid (1 g, 7.6 mmol) in absolute ethanol (20 mL) is added dropwise thionyl chloride (0.67 mL, 9.15 mmol) at 0° C. under nitrogen atmosphere. The reaction mixture is then refluxed under nitrogen for about 2 h. The mixture is cooled to room temperature, and all solvent is removed under reduced pressure. The white precipitate is filtered and washed with diethyl ether (1×25 mL), to obtain compound (1) as a white solid. The reaction mixture is then refluxed under nitrogen for about 2 h all solvent is removed under reduced pressure The white precipitate is filtered washed with diethyl ether (1×25 mL)

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

Procedure: To a stirred solution of cis-4-hydroxy-pyrrolidine-2-carboxylic acid (1 g, 7.6 mmol) in absolute ethanol (20 mL) is added dropwise thionyl chloride (0.67 mL, 9.15 mmol) at 0° C. under nitrogen atmosphere. The reaction mixture is then refluxed under nitrogen for about 2 h. The mixture is cooled to room temperature, and all solvent is removed under reduced pressure. The white precipitate is filtered and washed with diethyl ether (1×25 mL), to obtain compound (1) as a white solid. The reaction mixture is then refluxed under nitrogen for about 2 h all solvent is removed under reduced pressure The white precipitate is filtered washed with diethyl ether (1×25 mL)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a cold solution of 4-hydroxy-pyrrolidine-2-carboxylic acid ethyl ester (1) (1.4 g, 7.1 mmol) and triethyl amine (0.998 mL, 7.1 mmol) in pyridine (14 mL) at −5° C. was added portion-wise 4-toluenesulfonyl chloride (3.42 g, 17.9 mmol). The cold solution was then stirred for 1 h at 0° C. and stored overnight in the refrigerator. Then the mixture was further stirred at room temperature for 5 h and poured into ice water (10 mL). The precipitate separated out was filtered, washed with water (2×5 mL), and dried to give compound (2) as a white solid. stored overnight in the refrigerator Then the mixture was further stirred at room temperature for 5 h The precipitate separated out was filtered washed with water (2×5 mL) dried