Sodium hydride (22 mg, 60% in oil) was added to a solution of (5R)-5-{(E)-2-(4-tert-butylphenyl)-2-[5-(1-hydroxyethyl)-6-methoxypyridin-2-yl]ethenyl}-1-(2,4-dimethoxybenzyl)pyrrolidin-2-one (100 mg) in tetrahydrofuran (2 mL) under ice-cooling, and the mixture was stirred at the same temperature for 15 minutes. The reaction solution was warmed to room temperature and carbon disulfide (66.7 μL) was added, followed by stirring for 30 minutes. Methyl iodide (68.5 μL) was added and the mixture was stirred for 3.5 hours. Water was added to the reaction solution, followed by extraction with chloroform. The organic layer was dried over anhydrous magnesium sulfate, after which the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=2:1→1:1) to give O-[1-(6-{(E)-1-(4-tert-butylphenyl)-2-[(2R)-1-(2,4-dimethoxybenzyl)-5-oxopyrrolidin-2-yl]ethenyl}-2-methoxypyridin-3-yl)ethyl] S-methyl carbonodithioate as a colorless oil (109 mg).
