5'-O-(4,4'-Dimethoxytrityl)thymidine → 3'-O-[2-(2-nitrophenyl)propoxycarbonyl]thymidine

Participants

Reaction Conditions

Reaction Steps

A solution of 2 g 5′-O-(4,4′-dimethoxytrityl)thymidine (3) (3.67 mmol) in 20 ml dichloromethane is added dropwise at 0° C. to 1.2 equiv N3-[2-(2-nitrophenyl)propoxycarbonyl]-N-methylimidazolium chloride (2) (4.4 mmol) in 30 ml dichloromethane through a molecular sieve 4 Å within 10 minutes. The reaction mixture was stirred at 0° C. overnight, then extracted using 0.5% HCl (100 ml), dried via Na2SO4 and evaporated. 10% trichloroacetic acid (70 ml) in dichloromethane is added to the organic phase and stirred for 2 minutes. Thereafter, the deep-red solution is extracted twice using saturated NaHCO3 (100 ml), dried via Na2SO4 and evaporated. Purification via flash chromatography (0-10% methanol in toluene/ethyl acetate (5:4)) yielded 1.53 g (93%) of the title compound.

Provenance & Evidence