A 150-ml round-bottom flask under argon was charged with ethyl 3-(1-chlorophthalazin-6-yl)-4-methylbenzoate (358 mg, 1096 μmol), iron(III) acetylacetonate (38.7 mg, 109.6 □mol), THF (4200 μl), and 1-methyl-2-pyrrolidinone (420 μl). Methylmagnesium bromide (1.4M solution in toluene/tetrahydrofuran (75:25); 1174 μl, 1643 μmol) was then added via a syringe to the resulting orange red suspension, causing an immediate color change to brown, and finally to violet. The resulting mixture was stirred for 10 min, and the reaction (which remained a suspension) was diluted with EtOAc and carefully quenched with a few drops of 10% aqueous HCl solution. The mixture was washed with saturated aqueous NaHCO3 solution and the organic layer was dried (MgSO4), filtered, and concentrated in vacuo. CombiFlash purification (20% to 90% EtOAc in Hexanes) afforded ethyl 4-methyl-3-(1-methylphthalazin-6-yl)benzoate as a light golden brown oil. MS (ES+): 307.1 (M+H)+.
