1-aminopiperazine-2,3-dione

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

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

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

Procedure: 1.9 pts. by wt. of 5-bromofurfural, 1.3 pts. by wt. of 1-amino-2,3-dioxo-piperazine and 7 pts. by vol. of glacial acetic acid were warmed to 90° for 10 minutes and then left for 30 minutes at RT. The precipitate is filtered off, washed with 3 pts. by vol. of glacial acetic acid and recrystallised from dimethylformamide, with the addition of animal charcoal. 1.1 pts. by wt. (38.5%) of 1-(5-bromofurfurylideneamino)-2,3-dioxo-piperazine are obtained as yellowish crystals of decomp. pt. 220°. The precipitate is filtered off washed with 3 pts by vol. of glacial acetic acid and recrystallised from dimethylformamide, with the addition of animal charcoal

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

Procedure: 1.6 pts. by wt. of 5-chloro-furfural, 1.3 pts. by wt. of 1-amino-2,3-dioxo-piperazine and 7 pts. by vol. of glacial acetic acid are warmed to 90° C. for 10 minutes and then left for 30 minutes at RT. The precipitate is filtered off, washed first with 3 pts. by vol. of glacial acetic acid and then twice with 10 pts. by vol. of acetonitrile each time and dried in air. 1.8 pts. by wt. (74.6%) of 1-(5-chloro-furfurylidene-amino)-2,3-dioxo-piperazine are obtained as yellowish crystals of decomp. pt. 233°-6° C. The precipitate is filtered off washed first with 3 pts by vol. of acetonitrile each time and dried in air

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

Procedure: 1.3 pts. by wt. of 1-amino-2,3-dioxo-piperazine, 1.3 pts. by wt. of 5-methyl-furfural and 7 pts. by vol. of glacial acetic acid are warmed to 90° C. for 10 minutes and then left for 30 minutes at RT. The precipitate is filtered off, washed first with 3 pts. by vol. of glacial acetic acid and then three times with 10 pts. by vol. of ethyl acetate and dried in air. 1.7 pts. by wt. (76.6%) of 1-(5-methyl-furfurylideneamino)-2,3-dioxo-piperazine of decomp. pt. 245°-8° C. are obtained. The precipitate is filtered off washed first with 3 pts by vol. of ethyl acetate and dried in air

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

Procedure: 2.3 pts. by wt. of furfural, 2.6 pts. by wt. of 1-amino-2,3-dioxo-piperazine and 10 pts. by vol. of glacial acetic acid are warmed to 90° for 30 minutes and thereafter left for 3 hrs. at RT, whereupon crystallisation occurs. The precipitate is filtered off, washed first with 5 pts. by vol. of glacial acetic acid and then twice with 10 pts. by vol. of ethyl acetate each time and dried over potassium hydroxide. 4.0 pts. by wt. (96.6%) of 1-furfurylideneamino-2,3-dioxo-piperazine of melting point 193°-7° are obtained. at RT, whereupon crystallisation The precipitate is filtered off washed first with 5 pts by vol. of ethyl acetate each time and dried over potassium hydroxide

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

Procedure: 1.3 pts. by wt. of 1-amino-2,3-dioxo-piperazine, 1.3 pts. by wt. of benzaldehyde and 7 pts. by vol. of glacial acetic acid are warmed to 90° for 90 minutes and then left at 5° for 30 minutes. The precipitate is filtered off, washed first with 3 pts. by vol. of glacial acetic acid and then with three times 10 pts. by vol. of ethyl acetate and dried over P2O5. 1.75 pts. by wt. (81.8% ) of 1-benzylideneamino-2,3-dioxo-piperazine of melting point 236°-240° C. are obtained. The precipitate is filtered off washed first with 3 pts by vol. of ethyl acetate and dried over P2O5

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

Procedure: To a suspension of 4,5-bis(phenylmethoxy)-2-pyridinecarboxylic acid (7.1 g, 21.17 mmol), hydroxybenzotriazole (0.29 g, 2.12 mmol) and N-aminopiperazine-2,3-dione (2.73 g, 21.17 mmol) in 140 ml of dry dimethylformamide was added, after 15 minutes of stirring, 4.80 g (23.3 mmol) of dicyclohexylcarbodiimide. After stirring for 21 hours at room temperature, dicyclohexylurea was filtered off (4.0 g ) and the solvent was evaporated in vacuo. The solid residue was triturated for 40 minutes with 240 ml of tetrahydrofuran, filtered, washed with tetrahyrofuran and dried in vacuo to yield 7.76 g of the title compound, melting point 231.1° C. was added, after 15 minutes After stirring for 21 hours at room temperature dicyclohexylurea was filtered off (4.0 g ) the solvent was evaporated in vacuo The solid residue was triturated for 40 minutes with 240 ml of tetrahydrofuran filtered washed with tetrahyrofuran dried in vacuo