1,4-dibenzylpiperazine-2,5-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:5.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Lithium bis(trimethylsilyl)amide (1.0M in tetrahydrofuran) (77 ml) was added portionwise to a stirred solution of 1,4-dibenzyl-2,5-piperazinedione (20.6 g) in a mixture of tetrahydrofuran (400 ml) and N,N-dimethylformamide (200 ml) at 0° C. The whole was stirred at 5° C. for 1 hour and thereto a solution of bromodiphenylmethane (19 g) in tetrahydrofuran (100 ml) was added at −78° C. and the mixture was stirred for 2 hours at the same temperature. After being stirred at 5° C. for 2 hours, the mixture was poured into ice-water and extracted with ethyl acetate. The extract was washed with 1N hydrochloric acid and brine, dried over sodium sulfate and concentrated under reduced pressure. The residue was triturated with a mixed solvent of ethyl acetate and isopropyl alcohol, and the resulting solid was collected by filtration to give 1,4-dibenzyl-3-benzhydryl-2,5-piperazinedione (10.55 g) as a colorless powder. the mixture was stirred for 2 hours at the same temperature After being stirred at 5° C. for 2 hours extracted with ethyl acetate The extract was washed with 1N hydrochloric acid and brine dried over sodium sulfate concentrated under reduced pressure The residue was triturated with a mixed solvent of ethyl acetate and isopropyl alcohol the resulting solid was collected by filtration

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate:40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-1-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR. (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate:40% hexanes)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate:40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-1-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR. (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate:40% hexanes)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate: 40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR. (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate: 40% hexanes)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate: 40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-1-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate: 40% hexanes)

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate:40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-1-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate:40% hexanes)

Conditions: temp:5.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Lithium bis(trimethylsilyl)amide (1.0M in tetrahydrofuran) (77 ml) was added portionwise to a stirred solution of 1,4-dibenzyl-2,5-piperazinedione (20.6 g) in a mixture of tetrahydrofuran (400 ml) and N,N-dimethylformamide (200 ml) at 0° C. The whole was stirred at 5° C. for 1 hour and thereto a solution of bromodiphenylmethane (19 g) in tetrahydrofuran (100 ml) was added at −78° C. and the mixture was stirred for 2 hours at the same temperature. After being stirred at 5° C. for 2 hours, the mixture was poured into ice-water and extracted with ethyl acetate. The extract was washed with 1N hydrochloric acid and brine, dried over sodium sulfate and concentrated under reduced pressure. The residue was triturated with a mixed solvent of ethyl acetate and isopropyl alcohol, and the resulting solid was collected by filtration to give 1,4-dibenzyl-3-benzhydryl-2,5-piperazinedione (10.55 g) as a colorless powder. the mixture was stirred for 2 hours at the same temperature After being stirred at 5° C. for 2 hours extracted with ethyl acetate The extract was washed with 1N hydrochloric acid and brine dried over sodium sulfate concentrated under reduced pressure The residue was triturated with a mixed solvent of ethyl acetate and isopropyl alcohol the resulting solid was collected by filtration

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of commercially available 1,4-bis(phenylmethyl)piperazine-2,5-dione (2.0 g, 6.8 mmol) in dry THF (50 mL) at −78° C. was added lithium diisopropylamide (2.0 M solution in heptane/THF/ethylbenzene, 3.4 mL, 6.8 mmol). The resulting reddish brown suspension was stirred for 23 min at −78° C., and then a solution of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (770 mg, 4.5 mmol) in THF (10 mL) was added over 30 min by syringe pump. The mixture became a bright yellow solution as it was allowed to warm to room temperature over 3 hours. The mixture was quenched with saturated aqueous ammonium chloride. Water was added to dissolve precipitated salts, and the resulting mixture was extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated. The residue was purified by column chromatography (60% ethyl acetate:40% hexanes) to provide 1,1-dimethylethyl 3-[3,6-dioxo-1,4-bis(phenylmethyl)piperazin-2-yl]-3-hydroxyazetidine-1-carboxylate as a colorless foam (1.04 g, 2.23 mmol, 50% yield). 1H NMR. (400 MHz, CDCl3): 7.39-7.29 (m, 7H), 7.23-7.19 (m, 3H), 5.34 (d, 1H), 4.82 (d, 1H), 4.58 (d, 1H), 4.37 (d, 1H), 4.37 (d, 1H), 4.22 (d, 1H), 4.15 (s, 1H), 4.08 (d, 1H), 3.97 (d, 1H), 3.75 (d, 1H), 3.74 (d, 1H), 3.67 (d, 1H), 3.64 (br s, 1H), 1.43 (s, 9H). to warm to room temperature over 3 hours The mixture was quenched with saturated aqueous ammonium chloride Water was added to dissolve precipitated salts the resulting mixture was extracted twice with ethyl acetate The combined organic extracts were dried over magnesium sulfate filtered concentrated The residue was purified by column chromatography (60% ethyl acetate:40% hexanes)