To a solution of 5-iodo-2-oxoindoline (497 mg, 1.9 mmol) in THF (20 ml) were added triethylamine (0.80 ml, 5.7 mmol), 3,3-diethoxyprop-1-yne (738 mg, 5.7 mmol), CuI (73 mg, 0.38 mmol) and Pd(PPh3)4 (222 mg, 0.19 mmol). The reaction mixture was stirred for 4 h at 50° C. The mixture was poured into H2O and EtOAc. The mixture was separated into an aqueous layer and an organic layer. The aqueous layer was extracted with ethyl acetate 3 times. The combined organic layer was washed with sat. NaHCO3 solution, and brine, and then dried over Na2SO4. The solvent was evaporated and the residue purified by column chromatography (EtOAc then CHCl3/MeOH) to give 5-(3,3-diethoxyprop-1-ynyl)indolin-2-one as a brown solid (292 mg, 59%).
