Diisopropylethylamine → 4-N-acetyl-5'-O-(4,4'-dimethoxytrityl)-2'-O-(2-cyanoethoxymethyl)cytidine

Participants

Reaction Steps

N4-Acetyl-5′-O-(4,4′-dimethoxytrityl)cytidine (588 mg, 1 mmol) was dissolved in 4 mL of 1,2-dichloroethane, and 452 mg of diisopropylethylamine (3.5 mmol) was added thereto, and then 365 mg of dibutylstannyl dichloride (1.2 mmol) was further added. The reaction was performed at room temperature for 1 hour. Then, the reaction was performed at 80° C., and 155.4 mg of chloromethyl 2-cyanoethyl ether (1.3 mmol) was added dropwise, and the solution was stirred for 60 minutes. After the reaction completed, the reaction solution was added into an aqueous saturated sodium bicarbonate solution, and was extracted with methylene chloride. The extract was dried over anhydrous magnesium sulfate, and the solvent was distilled off. The obtained mixture was purified by 30 g of silica gel column chromatography to obtain N4-acetyl-5′-O-(4,4′-dimethoxytrityl)-2′-O-(2-cyanoethoxymethyl) cytidine (219 mg, yield 35%).

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