反应详情

A suspension of a 2-fluoroadenine (107.8 mg, 0.70 mmol) and ammonium sulfate (5.3 mg) in 1,1,1,3,3,3-hexamethyldisilazane (HMDS) (10 ml) is refluxed under argon for 7 h. More ammonium sulfate (4.6 mg) is added, and reflux is continued for 24 h. After cooling the reaction mixture to room temperature, the HMDS is removed in vacuo, and the residue is co-evaporated with anhydrous toluene (3×3 ml). To this material is added 1-O-acetyl-2,3,5-tri-O-benzoyl-L-lyxofuranose (212 mg, 0.42 mmol) dissolved in anhydrous acetonitrile (7 ml). The resulting suspension is chilled to −10° C. before being treated dropwise over 5 min with 2.1 ml of 1.0 M stannic chloride (SnCl4) in dichloromethane. The now clear reaction solution is warmed to 0° C. over 15 min and then stirred at room temperature. After 3 h, the solution is added dropwise to ice-cold saturated NaHCO3 (100 ml) and stirred 10 min at 5° C. Ethyl acetate (75 ml) is added, and the separated aqueous layer is extracted with more ethyl acetate (2×50 ml). The combined organics are washed with brine (50 ml), dried (MgSO4), and evaporated to a solid. Column chromatography on 20 g silica gel (95:5 chloroform-methanol) gave 1 a as a white solid after ethanol crystallization.

1. temperatureis refluxed under argon for 7 h
2. temperaturereflux
3. customthe HMDS is removed in vacuo
4. temperatureThe resulting suspension is chilled to −10° C.
5. temperatureThe now clear reaction solution is warmed to 0° C. over 15 min
6. waitAfter 3 h
7. stirringstirred 10 min at 5° C
8. extractionthe separated aqueous layer is extracted with more ethyl acetate (2×50 ml)
9. washThe combined organics are washed with brine (50 ml)
10. dry with materialdried (MgSO4)
11. customevaporated to a solid
12. customColumn chromatography on 20 g silica gel (95:5 chloroform-methanol) gave 1 a as a white solid
13. customafter ethanol crystallization