Under argon, to a solution of 2-iodoadenosine (420 mg, 1.07 mmol) and bis(triphenylphosphine)palladium dichloride (75 mg, 10 mol %) dissolved in N,N-dimethylformamide (10 mL), diisopropylamine (0.18 mL, 1.28 mmol, 1.2 eq.) and 6-cyano-1-hexyne (137 mg, 1.28 mmol, 1.2 eq.) were added, and, under ice-cooling conditions, cuprous iodide (10 mg, 5 mol %) was added thereto, followed by stirring at 50° C. for 24 hours. The reaction mixture was cooled to room temperature, and the solvent was removed under reduced pressure. The residue was purified by dry packed silica gel column chromatography (ethyl acetate:methanol=10:1), to thereby yield a compound of the present invention as a pale yellow powder (yield: 217 mg, percent yield: 55%).
