Dimethyl Sulfoxide → 5'-Carbethoxymethylene-3'-azido-5',3'dideoxythymidine

Participants

Reaction Steps

A solution of DMSO(426 μl, 6 mM) in methylene chloride (1.5 ml) was added to a stirred solution of oxalyl chloride (288 μl, 3.3 mM) in methylene chloride (7.6 ml) at -78° C. under nitrogen. After 5 minutes, a solution of 3'-azido-3'-deoxythymidine (801 mg; 3 mM) in DMSO/CH2Cl2 (1.12 ml/3.47 ml) was added over a ten minute period. Stirring was continued for 20 minutes, and then triethylamine (2.09 ml, 15 mM) was added and the reaction mixture was stirred for an additional 5 minutes. (Carbethoxymethylene)triphenylphosphorane (1.57 g; 4.5 mM) was added in a solution of methylene chloride (9 ml), and the reaction mixture was stirred at -78° C. for 30 minutes and then allowed to stand at room temperature for 1 hour. The crude reaction mixture was then quenched with cold water (20 ml) and extracted into ethyl acetate (2×50 ml), washed with brine and dried over anhydrous sodium sulfate. The crude product was purified by flash chromatography (SiO2 : 60 g; 60% ethyl acetate/hexane) to afford 765 mg (76%) of the title compound. Rf -0.47(7/3 EtOAc/Hexane).

Provenance & Evidence