Acetamide, N-[(dimethylamino)methylidene]- → N-[(E)-[(2-bromo-5-fluorophenyl)hydrazinylidene]methyl]acetamide

Alternatively, to a mixture of (2-bromo-5-fluoro-phenyl)-hydrazine hydrochloride (5.9 g, 28.8 mmol) and N-((dimethylamino)methylene)acetamide (3.30 g, 28.8 mmol) in THF (30 mL) was added 5 drops of HOAc, and the mixture stirred at room temperature under nitrogen for 15 min. The mixture was concentrated in vacuo, and the residue suspended in a mixture of ether (50 mL) and hexanes (50 mL) and the resulting precipitate collected and air-dried to provide 5.7 g of the title compound as an off-white powder. A second crop gave an additional 0.3 g.