ethyl (3R)-3-amino-2,5-dioxopyrrolidine-3-carboxylate

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (24.4 g, 76.2 mmol) in ethanol (73.2 ml) was heated at 60° C. to be dissolved and 5% Pd—C (2.71 g) and water (2.17 g) were added at 30-40° C. of inner temperature. After the atmosphere was substituted with nitrogen gas, hydrogen gas was introduced and the mixture was stirred at 30-40° C. for about 33 hours. When completion of the reaction was confirmed by HPLC, the reaction solution was filtered, the insoluble materials were washed with sprayed ethanol (20 ml×2) and the filtrate was concentrated. The resulting crystals were recrystallized from ethanol (24.4 ml) and the precipitated crystals were filtered, washed with sprayed ethanol (15 ml) and dried in vacuo at room temperature to give (2R)-2-amino-2-ethoxycarbonylsuccinimide (12.3 g). Yield 86.7%, HPLC 99.7%, Optical purity 100% e.e. to be dissolved was introduced the reaction solution was filtered the insoluble materials were washed with sprayed ethanol (20 ml×2) the filtrate was concentrated The resulting crystals were recrystallized from ethanol (24.4 ml) the precipitated crystals were filtered washed with sprayed ethanol (15 ml) dried in vacuo at room temperature

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (24.4 g, 76.2 mmol) in ethanol (73.2 ml) was heated at 60° C. to be dissolved and 5% Pd—C (2.71 g) and water (2.17 g) were added at 30-40° C. of inner temperature. After the atmosphere was substituted with nitrogen gas, hydrogen gas was introduced and the mixture was stirred at 30-40° C. for about 33 hours. When completion of the reaction was confirmed by HPLC, the reaction solution was filtered, the insoluble materials were washed with sprayed ethanol (20 ml×2) and the filtrate was concentrated. The resulting crystals were recrystallized from ethanol (24.4 ml) and the precipitated crystals were filtered, washed with sprayed ethanol (15 ml) and dried in vacuo at room temperature to give (2R)-2-amino-2-ethoxycarbonylsuccinimide (12.3 g). Yield 86.7%, HPLC 99.7%, Optical purity 100% e.e. to be dissolved was introduced the reaction solution was filtered the insoluble materials were washed with sprayed ethanol (20 ml×2) the filtrate was concentrated The resulting crystals were recrystallized from ethanol (24.4 ml) the precipitated crystals were filtered washed with sprayed ethanol (15 ml) dried in vacuo at room temperature

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (24.4 g, 76.2 mmol) in ethanol (73.2 ml) was heated at 60° C. to be dissolved and 5% Pd—C (2.71 g) and water (2.17 g) were added at 30-40° C. of inner temperature. After the atmosphere was substituted with nitrogen gas, hydrogen gas was introduced and the mixture was stirred at 30-40° C. for about 33 hours. When completion of the reaction was confirmed by HPLC, the reaction solution was filtered, the insoluble materials were washed with sprayed ethanol (20 ml×2) and the filtrate was concentrated. The resulting crystals were recrystallized from ethanol (24.4 ml) and the precipitated crystals were filtered, washed with sprayed ethanol (15 ml) and dried in vacuo at room temperature to give (2R)-2-amino-2-ethoxycarbonylsuccinimide (12.3 g). Yield 86.7%, HPLC 99.7%, Optical purity 100% e.e. to be dissolved was introduced the reaction solution was filtered the insoluble materials were washed with sprayed ethanol (20 ml×2) the filtrate was concentrated The resulting crystals were recrystallized from ethanol (24.4 ml) the precipitated crystals were filtered washed with sprayed ethanol (15 ml) dried in vacuo at room temperature

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (24.4 g, 76.2 mmol) in ethanol (73.2 ml) was heated at 60° C. to be dissolved and 5% Pd—C (2.71 g) and water (2.17 g) were added at 30-40° C. of inner temperature. After the atmosphere was substituted with nitrogen gas, hydrogen gas was introduced and the mixture was stirred at 30-40° C. for about 33 hours. When completion of the reaction was confirmed by HPLC, the reaction solution was filtered, the insoluble materials were washed with sprayed ethanol (20 ml×2) and the filtrate was concentrated. The resulting crystals were recrystallized from ethanol (24.4 ml) and the precipitated crystals were filtered, washed with sprayed ethanol (15 ml) and dried in vacuo at room temperature to give (2R)-2-amino-2-ethoxycarbonylsuccinimide (12.3 g). Yield 86.7%, HPLC 99.7%, Optical purity 100% e.e. to be dissolved was introduced the reaction solution was filtered the insoluble materials were washed with sprayed ethanol (20 ml×2) the filtrate was concentrated The resulting crystals were recrystallized from ethanol (24.4 ml) the precipitated crystals were filtered washed with sprayed ethanol (15 ml) dried in vacuo at room temperature

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol

Conditions: temp:35.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (2R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (24.4 g, 76.2 mmol) in ethanol (73.2 ml) was heated at 60° C. to be dissolved and 5% Pd—C (2.71 g) and water (2.17 g) were added at 30-40° C. of inner temperature. After the atmosphere was substituted with nitrogen gas, hydrogen gas was introduced and the mixture was stirred at 30-40° C. for about 33 hours. When completion of the reaction was confirmed by HPLC, the reaction solution was filtered, the insoluble materials were washed with sprayed ethanol (20 ml×2) and the filtrate was concentrated. The resulting crystals were recrystallized from ethanol (24.4 ml) and the precipitated crystals were filtered, washed with sprayed ethanol (15 ml) and dried in vacuo at room temperature to give (2R)-2-amino-2-ethoxycarbonylsuccinimide (12.3 g). Yield 86.7%, HPLC 99.7%, Optical purity 100% e.e. to be dissolved was introduced the reaction solution was filtered the insoluble materials were washed with sprayed ethanol (20 ml×2) the filtrate was concentrated The resulting crystals were recrystallized from ethanol (24.4 ml) the precipitated crystals were filtered washed with sprayed ethanol (15 ml) dried in vacuo at room temperature

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

Procedure: (R)-2-Benzyloxycarbonylamino-2-ethoxycarbonylsuccinimide (80 mg) was dissolved in ethanol (10 mL), the solution was added with 5% palladium/carbon (4 mg), and catalytic hydrogenation was performed at room temperature under a hydrogen atmosphere. After the catalyst was removed by filtration, the filtrate was concentrated under reduced pressure. The residue was recrystallized from ethanol to obtain the title compound (43 mg, yield: 93%) as colorless crystals. Optical rotation [α]D24 was −35.9° (c 0.22, ethanol). Optical purity was more than 99.9% ee. was performed at room temperature under a hydrogen atmosphere After the catalyst was removed by filtration the filtrate was concentrated under reduced pressure The residue was recrystallized from ethanol