反应详情

A mixture of methyl (2Z)-2-acetyl-3-(4-fluorophenyl)-2-propenoate (0.220 mole, 48.8 g), O-methyl isourea hydrogensulfate (53.40 g, 0.310 mol, 1.5 eq.), NaHCO3 (61.74 g, 0.74 mole, 3.5 equiv.) and ethanol (1.2 L) was refluxed for 24 h, cooled to room temperature, and filtered. The solid was washed with ethanol (200 mL) and the combined filtrate was concentrated in vacuo. The residue was purified by chromatography (silica gel, hexanes/EtOAc/Et3N 50:50:0.1) to yield a mixture of tautomers (4:1, 33.0 g, 53.9%). 1H NMR (CDCl3) δ 7.32-7.24 (m, 2H), 7.04-6.95 (m, 2H), 5.81 (s, 1H), 5.38 (d, 1H, J=2.9 Hz), 4.00 (s, 3H), 3.63 (s, 3H), 2.34 (s, 3H).

1. temperaturewas refluxed for 24 h
2. filtrationfiltered
3. washThe solid was washed with ethanol (200 mL)
4. concentrationthe combined filtrate was concentrated in vacuo
5. customThe residue was purified by chromatography (silica gel, hexanes/EtOAc/Et3N 50:50:0.1)
6. customto yield
7. additiona mixture of tautomers (4:1, 33.0 g, 53.9%)