A mixture of 5-iodo-2'-deoxyuridine (3.54 g, 10 mmol), copper(1) iodide (0.19 g, 1 mmol) and tetrakis(triphenylphosphine)palladium(O) (0.58 g, 0.5 mmol) is dried in vacuo at 60° for 3 hours and placed under argon. A suspension of the mixture in dry DMF (20 ml) is stirred under argon and treated with dry triethylamine (1.7 ml, 12 mmol) followed by 3-(2-Trifluoroacetamidoethoxy)propyne (3.17 g, 16 mmol). The mixture is cooled at room temperature in a water bath and stirred for 17 hours. The mixture is treated with 2% acetic acid (100 ml), the catalyst is removed by filtration and washed with 50% methanol. The filtrates are combined and passed onto a LiChroprep RP-18 column (5×25 cm), the column is washed, then eluted with 1% acetic acid in 50% (v/v) methanol. The fractions with the main product are combined, evaporated, and dried in vacuo. The resultant foam is stirred with 150 ml of ether to give crystalline product; yield 3.6 g (85%); m.p. 145°-152°.
