A solution of 8-chloro-9-iodo-4,6-dimethylbenzo[c][2,7]naphthyridin-5(6H)-one (1.2 g, 2.71 mmol), 2,4,6-trivinylcyclotriboroxane pyridine complex (0.784 g, 3.26 mmol), tetrakis(triphenylphosphine)palladium (0.157 g, 0.136 mmol) and Na2CO3 (0.575 g, 5.43 mmol) in toluene (30 mL) and water (0.5 mL) was purged with nitrogen and heated at 90° C. for 16 h. After cooling to room temperature, the mixture was concentrated under reduced pressure. The residue was taken up in ethyl acetate and filtered through diatomaceous earth (Celite®). The EtOAc layer was washed with brine and water. The combined organic layers were dried over Na2SO4, filtered and concentrated under reduced pressure. The crude material was purified by silica gel flash chromatography using EtOAc-hexane as the eluent to afford 8-chloro-4,6-dimethyl-9-vinylbenzo[c][2,7]naphthyridin-5(6H)-one (0.6 g, 1.43 mmol, 68% yield)) as brown gummy solid. LC/MS (ESI) m/e 285.0 [(M+H)+, calcd for C16H14ClN2O, 285.1]; LC/MS retention time (method B): tR=2.25 min.
