Acetic Anhydride → 5'-O-Benzoyl-2',3'-didehydro-3'-deoxy-4'-ethynylthymidine

Participants

Reaction Conditions

Reaction Steps

A mixture of NaBH4 (628 mg, 16.6 mmol) and MeOH (50 ml) was cooled and stirred at −70° C. To this was added a mixture of 5 (3.39 g, 8.3 mmol) and CeCl3.7H2O (3.1 g, 8.3 mmol) in THF/MeOH=1/1 (50 ml) dropwise over 15 min. The resulting suspension was stirred for 1 h at the −70□. The reaction was quenched by adding AcOH (ca. 1 mL). The reaction mixture was evaporated. The residue was suspended in MeCN (15 ml). To this suspension were added DMAP (1.02 g, 8.3 mmol), i-Pr2NEt (1.45 mL, 8.3 mmol) and Ac2O (1.57 mL, 16.6 mmol). The mixture was stirred for 30 min at 0° under positive pressure of dry Ar, and partitioned between CH2Cl2 and sat. aqueous NaHCO3. The organic layer was dried (Na2SO4), evaporated, and chromatographed on a silica gel column (hexane/EtOAc=4/1). This gave 6 (3.74 g, 100%) as an oil.

Provenance & Evidence