反应详情

To a solution of 4-aminobenzoic acid (411 mg, 3.00 mmol) in DMF (3.0 mL) at room temperature was added EDC (862 mg, 4.50 mmol), HOBt (608 mg, 4.50 mm01), triethylamine (606 mg, 0.835 mL, 6.00 mmol) and tert-butyl piperazinecarboxylate (671 mg, 3.60 mmol). The mixture was stirred for 22 h, and then 2 N aq. NaOH was added to adjust the PH>10. The mixture was extracted with ethyl acetate, and the organic layer was dried over MgSO4, concentrated. The residue was purified by silica gel column chromatograghy eluted with EtOAc:hexanes (50 to 90% EtOAc) to give 4-(4-amino-benzoyl)-piperazine-1-carboxylic acid tert-butyl ester (796 mg, 87%) as a colorless oil. MS (ES+): m/z=306.2

1. extractionThe mixture was extracted with ethyl acetate
2. dry with materialthe organic layer was dried over MgSO4
3. concentrationconcentrated
4. customThe residue was purified by silica gel column chromatograghy
5. washeluted with EtOAc