Hexamethyldisilazane → 3'-Deoxy-5'-O-(4-methoxytrityl)-3'-methyl-2'-O-(2-methoxyethyl)-5-methyluridine

Participants

Reaction Steps

A mixture of ammonium phosphinate (410 mg, 5.1 mmol) and 1,1,1,3,3,3-hexamethyldisilazane (1.18 mL, 0.90 g, 5.59 mmol) was heated at 100–110° C. for 2 h under nitrogen atmosphere with condenser. The intermediate BTSP (bis[trimethylsilyl]phosphinate) was cooled to 0° C. and 5 mL of dichloromethane was injected. To this mixture was injected a solution of 3′-deoxy-5′-O-(4-methoxytrityl)-3′-(iodomethyl)-2′-O-(2-methoxyethyl)-5-methyluridine (0.78 g, 1.1 mmol) and diisopropylethylamine (0.39 mL, 287 mg, 2.23 mmol) in 7 mL of dichloromethane. After the reaction mixture was stirred at rt overnight, a mixture of THF-MeOH—NEt3 (3/6/0.3 mL) was added and continued to stir for 1 h. The reaction mixture was filtered through a pad of celite and washed with dichloromethane. The solvent was evaporated and the residue was purified by flash chromatography on a silica gel column using 2:1, 1:1, and then 1:2 hexanes-EtOAc as eluent providing 380 mg of the title compound.

Provenance & Evidence