Under N2, 7-bromo-2-chloro-quinoxaline (20 g; 82.1 mmol), 1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (17.1 g; 82.1 mmol), 2M sodium carbonate aqueous solution (41.1 mL; 82.1 mmol) in ethylene glycol dimethyl ether (200 mL) were degassed by bubbling nitrogen through for 15 minutes. Tetrakis(triphenylphosphine)palladium (0) (0.95 g; 0.82 mmol) was added and heated at reflux for 15 hours. The reaction mixture was poured into water and extracted with EtOAc. The organic layer was dried over MgSO4, filtered and evaporated to dryness to give 29.9 g. The crude compound was purified by chromatography over silica gel (Irregular SiOH, 20-45 μm, 1000 g MATREX; mobile phase 0.1% NH4OH, 98% DCM, 2% CH3OH). The pure fractions were collected and concentrated till dryness to give 19.5 g (82%) of 7-Bromo-2-(1-methyl-1H-pyrazol-4-yl)-quinoxaline. MP=172° C.
