To a stirred suspension of 9-bromo-1,6-dichlorobenzo[c]-1,6-naphthyridine (5 g, 15.24 mmol) in Toluene (50 ml) was added tert-butyl 2-methylpropanoate (2.64 g, 18.29 mmol). The reaction mixture was cooled to 0° C. A solution of NaHMDS (1M in THF, 3.35 g, 18.29 mmol) was added dropwise, and the reaction mixture was allowed to warm to room temperature. After 5 hours, the reaction was quenched with aqueous saturated ammonium chloride (50 mL), and extracted with EtOAc (1×100 mL). The organic layer was dried over sodium sulfate, filtered and concentrated. The residue was adsorbed on to silica gel and purified by column chromatography on silica gel, eluting with an EtOAc/Hexanes gradient to afford tert-butyl 2-(9-bromo-1-chlorobenzo[c]-1,6-naphthyridin-6-yl)-2-methylpropanoate. LRMS (ESI) calc'd for (C20H20BrClN2O2) [M+H]+, 437.0; found 437.0.
