To a solution of 6-trifluoromethylsulfonyloxy-8-(3-nitrophenyl)-1,7-naphthyridine (200 mg, 0.50 mmol; prepared according to example 13) in dimethylformamide (1 ml) and triethylamine (0.5 ml) is added ethynyltrimethylsilane (0.078 ml, 0.56 mmol), bis(dibensylideneacetone)palladium (5.8 mg, 0.020 mmol), triphenylphosphine (5.3 mg, 0.020 mmol) and copper iodide (3.8 mg, 0.020 mmol). The mixture is kept at 60° C. for 2 h. The solution is diluted with ethyl acetate and washed with water. The product is purified by flash column chromatography on silica gel (20:0.2 toluene/acetone) affording 6-trimethylsilylethynyl-8-(3-nitrophenyl)-1,7-naphthyridine. (Mass M+H 348; mp 160-163° C.)
