反应详情

750 mg of 4-t-butoxycarbonyl-1-(4-nitrobenzyloxycarbonylamidino)piperazine [prepared as described in step (b) above] were dissolved in 10 ml of trifluoroacetic acid, and the resulting solution was stirred at room temperature for 30 minutes. At the end of this time, the reaction mixture was concentrated by evaporation under reduced pressure, and the resulting residue was dissolved in a mixture of ethyl acetate and water, and an aqueous solution of sodium hydrogencarbonate was added thereto to make the mixture alkaline. The ethyl acetate layer was separated and the aqueous layer was extracted with ethyl acetate three times. The ethyl acetate layer and all of the ethyl acetate washings were combined and concentrated by evaporation under reduced pressure, to obtain 530 mg of the title compound, as a powder.

1. concentrationAt the end of this time, the reaction mixture was concentrated by evaporation under reduced pressure
2. dissolutionthe resulting residue was dissolved in a mixture of ethyl acetate and water
3. additionan aqueous solution of sodium hydrogencarbonate was added
4. customThe ethyl acetate layer was separated
5. extractionthe aqueous layer was extracted with ethyl acetate three times
6. concentrationconcentrated by evaporation under reduced pressure