Selenium Dioxide → 1-(4-Fluorophenyl)-2-(4-pyridinyl)-1,2-ethanedione

A solution of selenium dioxide (4.82 g, 43.4 mmol) in H2O (20 mL) was added to a solution of 1-(4-fluorophenyl)-2-(4-pyridyl)-2-ethanone (9.33 g, 43.4 mmol) in dioxane (100 mL) and the resulting mixture was heated at reflux for 2 h. This mixture was concentrated in vacuo, triturated with ethyl acetate and filtered. The residue was purified by column chromatography using ethyl acetate/hexane (1:1) as an eluent to give 1-(4-fluorophenyl)-2-(4-pyridyl)-1,2-ethandione. A mixture of ammonium acetate (25.25 g, 0.328 mol) and hexamethylenetetraamine (9.18 g, 65.5 mmol) was added to a solution of the isolated dione dissolved in acetic acid (150 mL). This mixture was stirred at 80° C. for 2 h, poured into concentrated ammonium hydroxide (200 mL) and the resulting precipitate was filtered, washed with H2O and dried to give the title compound as a solid: mp 242-44.3° C.; MS 240 (MH+).