(2S,4R)-1-Boc-2-carbamoyl-4-hydroxypyrrolidine

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

Procedure: 1.85 ml of methanesulfonyl chloride was added, whilst ice-cooling, to a solution of 5.0 g of (2S, 4R)-1-(t-butoxycarbonyl)-2-carbamoyl-4-hydroxypyrrolidine [prepared as described in step (2) above] in 250 ml of dry tetrahydrofuran, followed by 3.31 ml of triethylamine. The mixture was then stirred at 0° to 5° C. for 1 hour, after which it was poured into an aqueous solution of sodium chloride and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The residue was purified by chromatography through silica gel (eluted with a 9:1 by volume mixture of ethyl acetate and methanol) to afford 5.5 g of the title compound as colorless crystals. extracted with ethyl acetate The extract was washed with an aqueous solution of sodium chloride dried over anhydrous magnesium sulfate the solvent was removed by distillation under reduced pressure The residue was purified by chromatography through silica gel ( eluted with a 9:1 by volume mixture of ethyl acetate and methanol)

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

Procedure: 58 g of (2S, 4R)-1-(t-butoxycarbonyl)-4-hydroxy-2-pyrrolidinecarboxylic acid [prepared as described in step (1) above] were dissolved in 850 ml of dry tetrahydrofuran, and then 38.2 ml of triethylamine were added to the mixture at -15° to -20° C. A solution of 26.3 ml of ethyl chloroformate in 240 ml of dry tetrahydrofuran was then added dropwise to the mixture at -15° to -20° C., and the mixture was stirred at the same temperature for 35 minutes. At the end of this time, 258 ml of 28% w/v aqueous ammonium hydroxide were added to the mixture at -15° to -20° C., and the mixture was allowed to stand overnight at room temperature. Ammonium chloride was then added to the reaction mixture, which was then extracted with tetrahydrofuran. The extract was dried and freed from the solvent by distillation under reduced pressure. The resulting residue was triturated with diethyl ether to cause crystallization. The crystals were collected by filtration and washed with diethyl ether to afford 49.7 g of the title compound as colorless crystals, melting at 146°-148° C. were added to the mixture at -15° to -20° C. to stand overnight at room temperature was then extracted with tetrahydrofuran The extract was dried freed from the solvent by distillation under reduced pressure The resulting residue was triturated with diethyl ether crystallization The crystals were collected by filtration washed with diethyl ether

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

Procedure: 7.82 g (34 mmol) of tert-butyl (2S,4R)-2-(aminocarbonyl)-4-hydroxypyrrolidine-1-carboxylate was dissolved in 80 ml of pyridine and 12 ml (84 mmol) of trifluoroacetic anhydride was added to the solution dropwise, at −20 C□. The mixture was stirred at room temperature for a day. The excess of anhydride was hydrolised by addition of some drops of water. To this mixture 200 ml of ethyl acetate was added and it was washed with 10% aqueous hydrogen chloride (to pH 3-5), 50 ml 2 N solution of sodium hydroxide and 50 ml brine. The organic solution was dried over sodium sulphate and evaporated to result in an oil. Yield: 5.35 g (74%). (MH30)=213, (MH+)2=426. it was washed with 10% aqueous hydrogen chloride (to pH 3-5), 50 ml 2 N solution of sodium hydroxide and 50 ml brine The organic solution was dried over sodium sulphate evaporated to result in an oil

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

Procedure: 1.85 ml of methanesulfonyl chloride was added, whilst ice-cooling, to a solution of 5.0 g of (2S, 4R)-1-(t-butoxycarbonyl)-2-carbamoyl-4-hydroxypyrrolidine [prepared as described in step (2) above] in 250 ml of dry tetrahydrofuran, followed by 3.31 ml of triethylamine. The mixture was then stirred at 0° to 5° C. for 1 hour, after which it was poured into an aqueous solution of sodium chloride and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The residue was purified by chromatography through silica gel (eluted with a 9:1 by volume mixture of ethyl acetate and methanol) to afford 5.5 g of the title compound as colorless crystals. extracted with ethyl acetate The extract was washed with an aqueous solution of sodium chloride dried over anhydrous magnesium sulfate the solvent was removed by distillation under reduced pressure The residue was purified by chromatography through silica gel ( eluted with a 9:1 by volume mixture of ethyl acetate and methanol)

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

Procedure: 58 g of (2S, 4R)-1-(t-butoxycarbonyl)-4-hydroxy-2-pyrrolidinecarboxylic acid [prepared as described in step (1) aboveπ were dissolved in 850 ml of dry tetrahydrofuran, and then 38.2 ml of triethylamine were added to the mixture at -15° to -20° C. A solution of 26.3 ml of ethyl chloroformate in 240 ml of dry tetrahydrofuran was then added dropwise to the mixture at -15° to -20° C., and the mixture was stirred at the same temperature for 35 minutes. At the end of this time, 258 ml of 28% w/v aqueous ammonium hydroxide were added to the mixture at -15° to -20° C., and the mixture was allowed to stand overnight at room temperature. Ammonium chloride was then added to the reaction mixture, which was then extracted with tetrahydrofuran. The extract was dried and freed from the solvent by distillation under reduced pressure. The resulting residue was triturated with diethyl ether to cause crystallization. The crystals were collected by filtration and washed with diethyl ether to afford 49.7 g of the title compound as colorless crystals, melting at 146°-148° C. were added to the mixture at -15° to -20° C. to stand overnight at room temperature was then extracted with tetrahydrofuran The extract was dried freed from the solvent by distillation under reduced pressure The resulting residue was triturated with diethyl ether crystallization The crystals were collected by filtration washed with diethyl ether

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

Procedure: 1.85 ml of methanesulfonyl chloride was added, whilst ice-cooling, to a solution of 5.0 g of (2S, 4R)-1-(t-butoxycarbonyl)-2-carbamoyl-4-hydroxypyrrolidine [prepared as described in step (2) above] in 250 ml of dry tetrahydrofuran, followed by 3.31 ml of triethylamine. The mixture was then stirred at 0° to 5° C. for 1 hour, after which it was poured into an aqueous solution of sodium chloride and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The residue was purified by chromatography through silica gel (eluted with a 9:1 by volume mixture of ethyl acetate and methanol) to afford 5.5 g of the title compound as colorless crystals. extracted with ethyl acetate The extract was washed with an aqueous solution of sodium chloride dried over anhydrous magnesium sulfate the solvent was removed by distillation under reduced pressure The residue was purified by chromatography through silica gel ( eluted with a 9:1 by volume mixture of ethyl acetate and methanol)

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

Procedure: 58 g of (2S, 4R)-1-(t-butoxycarbonyl)-4-hydroxy-2-pyrrolidinecarboxylic acid [prepared as described in step (1) aboveπ were dissolved in 850 ml of dry tetrahydrofuran, and then 38.2 ml of triethylamine were added to the mixture at -15° to -20° C. A solution of 26.3 ml of ethyl chloroformate in 240 ml of dry tetrahydrofuran was then added dropwise to the mixture at -15° to -20° C., and the mixture was stirred at the same temperature for 35 minutes. At the end of this time, 258 ml of 28% w/v aqueous ammonium hydroxide were added to the mixture at -15° to -20° C., and the mixture was allowed to stand overnight at room temperature. Ammonium chloride was then added to the reaction mixture, which was then extracted with tetrahydrofuran. The extract was dried and freed from the solvent by distillation under reduced pressure. The resulting residue was triturated with diethyl ether to cause crystallization. The crystals were collected by filtration and washed with diethyl ether to afford 49.7 g of the title compound as colorless crystals, melting at 146°-148° C. were added to the mixture at -15° to -20° C. to stand overnight at room temperature was then extracted with tetrahydrofuran The extract was dried freed from the solvent by distillation under reduced pressure The resulting residue was triturated with diethyl ether crystallization The crystals were collected by filtration washed with diethyl ether

Conditions: temp:-20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2S,4R)-tert-Butyl 2-carbamoyl-4-hydroxypyrrolidine-1-carboxylate 13c (74 g, 0.3217 mol) was dissolved in 740 mL of pyridine with stirring under argon atmosphere. The mixture was cooled to −20° C. followed by dropwise addition of trifluoroacetic anhydride (169 g, 0.804 mol). Upon completion of the addition, the reaction mixture was warmed up to room temperature. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was quenched with water and diluted with 0.8 L of ethyl acetate. The separated organic phase was washed with 500 mL of saturated brine and neutralized with 400 mL of concentrated hydrochloric acid to slight acidity. The resulting mixture was washed with 300 mL of aqueous sodium hydroxide solution (2 M) and 500 mL saturated brine successively, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to obtain the title compound (2S,4R)-tert-butyl 2-cyano-4-hydroxypyrrolidine-1-carboxylate 13d (49.7 g, yield 73%) as a brown oil. Upon completion of the addition the reaction mixture was warmed up to room temperature The mixture was quenched with water diluted with 0.8 L of ethyl acetate The separated organic phase was washed with 500 mL of saturated brine and neutralized with 400 mL of concentrated hydrochloric acid to slight acidity The resulting mixture was washed with 300 mL of aqueous sodium hydroxide solution (2 M) and 500 mL saturated brine successively dried over anhydrous sodium sulfate filtered concentrated under reduced pressure

Conditions: temp:-15.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2S,4R)-1-(tert-Butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid 13b (86.4 g, 0.374 mol) was dissolved in 1.2 L of tetrahydrofuran followed by addition of triethylamine (41 g, 0.411 mol) under argon atmosphere. The reaction mixture was cooled to −15° C., ethyl chlorformate (43.84 g, 0.411 mol) was added. After the mixture was stirred for 10 minutes, aqueous ammonia (236.8 mL) was added. The reaction mixture was slowly warmed up to 5° C. during 2 hours followed by addition of ammonium chloride (32 g). The reaction mixture was stirred for 30 minutes and separated. The separated organic phase was dried over anhydrous sodium sulfate, and the aqueous phase was extracted with ethyl acetate (100 mL×2). The combined organic extracts were concentrated under reduced pressure to obtain the title compound (2S,4R)-tert-butyl 2-carbamoyl-4-hydroxypyrrolidine-1-carboxylate 13c (74 g, yield 86%) as a white solid. The reaction mixture was slowly warmed up to 5° C. during 2 hours The reaction mixture was stirred for 30 minutes separated The separated organic phase was dried over anhydrous sodium sulfate the aqueous phase was extracted with ethyl acetate (100 mL×2) The combined organic extracts were concentrated under reduced pressure

Conditions: temp:-20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2S,4R)-tert-Butyl 2-carbamoyl-4-hydroxypyrrolidine-1-carboxylate 13c (74 g, 0.3217 mol) was dissolved in 740 mL of pyridine with stirring under argon atmosphere. The mixture was cooled to −20° C. followed by dropwise addition of trifluoroacetic anhydride (169 g, 0.804 mol). Upon completion of the addition, the reaction mixture was warmed up to room temperature. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was quenched with water and diluted with 0.8 L of ethyl acetate. The separated organic phase was washed with 500 mL of saturated brine and neutralized with 400 mL of concentrated hydrochloric acid to slight acidity. The resulting mixture was washed with 300 mL of aqueous sodium hydroxide solution (2 M) and 500 mL saturated brine successively, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to obtain the title compound (2S,4R)-tert-butyl 2-cyano-4-hydroxypyrrolidine-1-carboxylate 13d (49.7 g, yield 73%) as a brown oil. Upon completion of the addition the reaction mixture was warmed up to room temperature The mixture was quenched with water diluted with 0.8 L of ethyl acetate The separated organic phase was washed with 500 mL of saturated brine and neutralized with 400 mL of concentrated hydrochloric acid to slight acidity The resulting mixture was washed with 300 mL of aqueous sodium hydroxide solution (2 M) and 500 mL saturated brine successively dried over anhydrous sodium sulfate filtered concentrated under reduced pressure

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

Procedure: 1.85 ml of methanesulfonyl chloride was added, whilst ice-cooling, to a solution of 5.0 g of (2S, 4R)-1-(t-butoxycarbonyl)-2-carbamoyl-4-hydroxypyrrolidine [prepared as described in step (2) above] in 250 ml of dry tetrahydrofuran, followed by 3.31 ml of triethylamine. The mixture was then stirred at 0° to 5° C. for 1 hour, after which it was poured into an aqueous solution of sodium chloride and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The residue was purified by chromatography through silica gel (eluted with a 9:1 by volume mixture of ethyl acetate and methanol) to afford 5.5 g of the title compound as colorless crystals. extracted with ethyl acetate The extract was washed with an aqueous solution of sodium chloride dried over anhydrous magnesium sulfate the solvent was removed by distillation under reduced pressure The residue was purified by chromatography through silica gel ( eluted with a 9:1 by volume mixture of ethyl acetate and methanol)

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

Procedure: 58 g of (2S, 4R)-1-(t-butoxycarbonyl)-4-hydroxy-2-pyrrolidinecarboxylic acid [prepared as described in step (1) aboveπ were dissolved in 850 ml of dry tetrahydrofuran, and then 38.2 ml of triethylamine were added to the mixture at -15° to -20° C. A solution of 26.3 ml of ethyl chloroformate in 240 ml of dry tetrahydrofuran was then added dropwise to the mixture at -15° to -20° C., and the mixture was stirred at the same temperature for 35 minutes. At the end of this time, 258 ml of 28% w/v aqueous ammonium hydroxide were added to the mixture at -15° to -20° C., and the mixture was allowed to stand overnight at room temperature. Ammonium chloride was then added to the reaction mixture, which was then extracted with tetrahydrofuran. The extract was dried and freed from the solvent by distillation under reduced pressure. The resulting residue was triturated with diethyl ether to cause crystallization. The crystals were collected by filtration and washed with diethyl ether to afford 49.7 g of the title compound as colorless crystals, melting at 146°-148° C. were added to the mixture at -15° to -20° C. to stand overnight at room temperature was then extracted with tetrahydrofuran The extract was dried freed from the solvent by distillation under reduced pressure The resulting residue was triturated with diethyl ether crystallization The crystals were collected by filtration washed with diethyl ether