反应详情

1-[2′-O-(2-Ethylacetyl)-3′,5′-bis-O-(2,4-dichlorobenzyl)-β-D-ribofuranosyl]thymine (9.92 g, 15.0 mmol) was dissolved in hot EtOH (150 mL) and the solution was cooled to ambient temperature in a water bath. To the solution was cautiously added NaBH4 (1.13 g, 30.0 mmol) over 10 minutes. After 3 hours additional NaBH4 (282 mg, 7.45 mmol) was added the mixture was stirred for 1 hour and left to stand for 8 hours. The pH was adjusted to 4 by addition of Saturated NH4Cl (25 mL) to give a gum. The solvent was decanted and evaporated in vacuo to afford a white solid which was dissolved in CH2Cl2 (250 mL). The gum was dissolved with saturated aqueous NaHCO3 and this solution was gently extracted with the CH2Cl2 containing the product. The organic layer was separated and the aqueous layer was extracted again with CH2Cl2 (2×50 mL). After combining the organic layers, the solvent was dried over MgSO4 and evaporated in vacuo to afford a white foam. The foam was dissolved in CH2Cl2 and purified by flash chromatography using hexanes-EtOAc, 20:80, to give the title compound as a white foam (8.39 g, 90%).

1. customover 10 minutes
2. waitleft
3. waitto stand for 8 hours
4. customto give a gum
5. customThe solvent was decanted
6. customevaporated in vacuo
7. customto afford a white solid which
8. extractionthis solution was gently extracted with the CH2Cl2 containing the product
9. customThe organic layer was separated
10. extractionthe aqueous layer was extracted again with CH2Cl2 (2×50 mL)
11. dry with materialthe solvent was dried over MgSO4
12. customevaporated in vacuo
13. customto afford a white foam
14. custompurified by flash chromatography