Trimethylsilyl triflate → 1-[(2S,4R,5R)-5-(5-amino-2,7-dioxo-6H-thiazolo[4,5-d]pyrimidin-3-yl)-4-azido-tetrahydrofuran-2-yl]ethyl benzoate

Participants

Reaction Conditions

Reaction Steps

To a suspension of 5-amino-3,6-dihydrothiazolo[4,5-d]pyrimidine-2,7-dione (186 mg, 1 mmol) in ACN (10 mL) was added BSA (630 mg, 3 mmol). The resulting reaction mixture was then stirred at 70° C. under argon for 0.5 hour to form a clear solution. After the solution was cooled to room temperature, 1-[(2S,4R)-4-azido-5-methoxy-tetrahydrofuran-2-yl]ethyl benzoate (compound 25k, 300 mg, 1.0 mmol) and TMSOTf (1.15 g, 5 mmol) were added in sequence. After being heated at 70° C. for 14 hours, the solvent was removed in vacuo. The residue was partitioned between EtOAc and saturated NaHCO3 solution (30 mL). The organic layer was separated and the aqueous phase was extracted with EtOAc (30 mL) twice. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated in vacuo to afford 600 mg crude product of 1-[(2S,4R,5R)-5-(5-amino-2,7-dioxo-6H-thiazolo[4,5-d]pyrimidin-3-yl)-4-azido-tetrahydrofuran-2-yl]ethyl benzoate (compound 25l), which was used in next step without further purification. MS obsd. (ESI+) [(M+H)+]: 442.

Provenance & Evidence