反应详情

4-Methylmorpholine (0.41 mL, 3.7 mmol) was added dropwise via a syringe pump to a mixture of ethyl 2-amino-3-oxobutanoate hydrochloride (565 mg, 3.12 mmol) and acetic anhydride (0.35 mL, 3.7 mmol) in DMF (2 mL) and THF (4 mL) at RT under N2 over a period of 30 min. The reaction was stirred for 1 h and water was then added. It was extracted with EtOAc. The organic layer was washed with saturated sodium bicarbonate, HCl (1 N) and brine, dried over sodium sulfate and concentrated. The residue was purified by ISCO FC with 0-40% EtOAc in hexane to give the title compound (73 mg, 13%) as a light-yellow crystalline solid. 1H NMR (400 MHz, CDCl3-d) δ ppm 6.60 (s, 1H) 5.22 (d, J=6.59 Hz, 1H) 4.25 (q, J=6.90 Hz, 2H) 2.36 (s, 3H) 2.04 (s, 3H) 1.28 (t, J=7.14 Hz, 2H).

1. extractionIt was extracted with EtOAc
2. washThe organic layer was washed with saturated sodium bicarbonate, HCl (1 N) and brine
3. dry with materialdried over sodium sulfate
4. concentrationconcentrated
5. customThe residue was purified by ISCO FC with 0-40% EtOAc in hexane