Carbamimidic acid, methyl ester, sulfate (1:1) → HCID 178498443, compound

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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).

Provenance & Evidence