N-BOC-2-MALEIMIDOETHYLAMINE

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

Procedure: (2-Maleimido)ethylcarbamic acid tert-butyl ester (48 mg, 0.2 mmol) was dissolved in a mixed solvent of trifluoroacetic acid and dichloromethane (30:70, 5 ml), followed by stirring at 0° C. for 2 hours, and then the reaction solution was concentrated. The thus obtained residue was dissolved in dichloromethane (20 ml), and a saturated aqueous sodium hydrogencarbonate solution (10 ml) was added thereto to separate the layers. The organic layer was dried over potassium hydrogencarbonate and filtered. The solvent was evaporated under reduced pressure to give 1-(2-aminoethyl)-3-pyrroline-2,5-dione (28 mg, 0.2 mmol, yield 100%). the reaction solution was concentrated The thus obtained residue was dissolved in dichloromethane (20 ml) a saturated aqueous sodium hydrogencarbonate solution (10 ml) was added to separate the layers The organic layer was dried over potassium hydrogencarbonate filtered The solvent was evaporated under reduced pressure

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

Procedure: A toluene solution of Mitsunobu reagent (diethyl azodicarboxylate) (1.106 g/ml, 8.2 mmol, 1.29 ml) was gradually added to a tetrahydrofuran solution (25 ml) of triphenylphosphine (2.15 g, 8.2 mmol) at −78° C. To the thus obtained solution, a tetrahydrofuran solution (5 ml) of (2-hydroxyethyl)carbamic acid tert-butyl ester (1.32 g, 8.2 mmol) and maleimide (794 mg, 8.2 mmol) was added, followed by stirring at −78° C. for 5 minutes and further stirring at room temperature for 36 hours. The thus obtained reaction solution was concentrated, ether was added thereto, and the formed precipitate was removed by filtration. The thus obtained filtrate was concentrated, and the resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate=1:1) to give 2-(maleimido)ethylcarbamic acid tert-butyl ester (531 mg, 2.53 mmol, yield 31%). further stirring at room temperature for 36 hours The thus obtained reaction solution was concentrated ether was added the formed precipitate was removed by filtration The thus obtained filtrate was concentrated the resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate=1:1)