A mixture of 4-isobutylbenzoic acid (0.28 g, 1.59 mmol), 1-hydroxybenzotriazole (0.042 g, 0.31 mmol), N-[(1H-1,2,3-benzotriazol-1-yloxy)(dimethylamino)methylene]-N-methylmethanaminium tetrafluoroborate (0.51 g, 1.59 mmol), diisopropylethylamine (1.4 mL, 7.86 mmol) and dioxane (4 mL) was stirred at room temperature for 1 hour. Ethyl 5-[amino(hydroxyimino)methyl]pyrazine-2-carboxylate (0.33 g, 1.57 mmol) was added to the reaction mixture, stirred for 1.5 hours at room temperature and 6 hours at 100° C. The reaction mixture was cooled to room temperature, quenched with H2O (10 mL) and filtered. The precipitate was dissolved in EtOAc (10 mL), washed with 1N NaOH (3×10 mL) and brine (2×10 mL), dried (Na2SO4), filtered and concentrated in vacuo to yield the title compound (0.15 g, 27%) as a white solid.
