To a solution of methyl 3-(6-bromo-1,2,3,4-tetrahydroquinolin-1-yl)-2-(4-fluorophenyl)quinoxaline-6-carboxylate (130 mg, 0.26 mmol) in dioxane (25 ml) was added morpholine (35 mg, 0.40 mmol) and Pd(dppf)2Cl2 (6.7 mg, 0.05 mmol) with stirring overnight maintained with atmosphere of CO (g) at 100° C. under 5 Atm. The reaction mixture was concentrated under vacuum to give a residue, which was applied onto a silica gel column with 1% methanol in dichloromethane to afford methyl 2-(4-fluorophenyl)-3-[6-[(morpholin-4-yl)carbonyl]-1,2,3,4-tetrahydroquinolin-1-yl]quinoxaline-6-carboxylate as a yellow solid (107 mg, 77%).
