Trifluoromethanesulfonic anhydride → 3'-Azido-ddA

Participants

Reaction Steps

A solution of 920 mg (2 mmol) of N6 -benzoyl-9-(5-O-benzoyl-2-deoxy-β-D-threopentofuranosyl)-adenine in 20 ml of abs. dichloromethane (and 2 ml of pyridine) is cooled to -30° C. Then 5 ml (3 mmol) of a solution of trifluoromethanesulfonic anhydride in abs. dichloromethane are added dropwise. The cooling bath is removed, the mixture is stirred for a further 20 min, and 980 mg (20 mmol) of lithium azide in 20 ml of DMF are added to the solution. After stirring at RT for a further 2 h, 50 ml of water and 150 ml of chloroform are added, and the organic phase is taken up and washed with distilled water. The solvent is removed in a ®Rotavapor and the product is treated with ammoniacal methanol solution overnight to remove the base protective group. Renewed removal of solvent is followed by purification by flash chromatography (chloroform:methanol 95:5) on silica gel. Yield: 430 mg (1.6 mmol, 79%) of white crystalline powder. IR: 2,100 cm-1 azido group.

Provenance & Evidence