Butyl vinyl ether → N-Methyl-N-phenylprop-2-enamide

To a solution of N-methylformanilide (30 g), butyl vinyl ether (22.2 g) in 25 ml of 1,4-dioxane under stirring at 10–15° C., a solution of bis-trichloromethylcarbonate (28.3 g) in 50 ml of 1,4-dioxane is added dropwise in 90 min. The reaction mixture is kept under stirring at room temperature overnight, then the solvent is evaporated under reduced pressure. Toluene (50 ml) and water (200 ml) are added, the mixture is cooled at about 5–10° C. and the pH is corrected to about 7 by adding sodium hydroxide 15% aqueous solution (30 ml). After separation of the phases, the aqueous layer is extracted twice with toluene (50 ml×2) and the combined organic layers are washed with water (50 ml) and evaporated under reduced pressure. The obtained residue (32.3 g, containing, according to HPLC assay, 28.7 g of pure product, 81% molar yield) is used for the next step of the synthesis without any further purification.