Reaction #6879

Reaction equation

sodium hydrogen carbonate

mixture 14

6-O-Benzoyl-1,2-di-O-acetyl-3,5-di-O-benzyl-D-allofuranose

thymine

Trimethylsilyl triflate

→

nucleoside

1-(2-O-acetyl-6-O-benzoyl-3,5-di-O-benzyl-β-D-allofuranosyl)thymine

Solvents

acetonitrile

Conditions

Workup

1. 1
   Temperaturecooled to 0° C
2. 2
   Temperaturethe mixture was heated for 2 h
3. 3
   Temperatureunder reflux
4. 4
   Temperatureto cool to room temperature
5. 5
   TemperatureAfter cooling to 0° C.
6. 6
   Extractionextraction
7. 7
   WashThe combined organic phase was washed with brine (50 cm3)
8. 8
   Dryingdried (Na2SO4)
9. 9
   Otherevaporated to dryness under reduced pressure
10. 10
    OtherThe residue was purified by silica gel column chromatography

Procedure

To a stirred suspension of the anomeric mixture 14 (4.50 g, 8.21 mmol) and thymine (1.55 g, 12.31 mmol) in anhydrous acetonitrile (50 cm3) was added N,O-bis(trimethylsilyl)-acetamide (12.2 cm3, 49.3 mmol). The reaction mixture was stirred at 60° C. for 1 h and then cooled to 0° C. Trimethylsilyl triflate (2.97 cm3, 16.4 mmol) was added dropwise during 10 min and the mixture was heated for 2 h under reflux. The reaction mixture was allowed to cool to room temperature and the volume was reduced by 50% under reduced pressure. After cooling to 0° C., a saturated aqueous solution of sodium hydrogen carbonate (100 cm3) was added and extraction was performed with dichloromethane (2×50 cm3). The combined organic phase was washed with brine (50 cm3), dried (Na2SO4) and evaporated to dryness under reduced pressure. The residue was purified by silica gel column chromatography using dichloromethane/methanol (99.5:0.5, v/v) as eluent to give nucleoside 15 as white solid material (4.06 g, 81%) after evaporation of the solvents under reduced pressure.

Source