Réaction #302914

Équation de réaction

5

1-[5-O-Benzoyl-2-deoxy-4-ethynyl-3-O-methanesulfonyl-β-D-threo-pentofuranosyl]thymine

MeOH

i-Pr2NEt

Ac2O

→

6

Rendement 127.9%

5′-O-Benzoyl-2′,3′-didehydro-3′-deoxy-4′-ethynylthymidine

Rendement 127.9%

Solvants

THF MeOH

Conditions de réaction

Traitement

1. 1
   Températurewas cooled
2. 2
   workup.ADDITIONTo this was added
3. 3
   workup.STIRRINGThe resulting suspension was stirred for 1 h at the −70□
4. 4
   AutreThe reaction was quenched
5. 5
   workup.ADDITIONby adding AcOH (ca. 1 mL)
6. 6
   AutreThe reaction mixture was evaporated
7. 7
   workup.STIRRINGThe mixture was stirred for 30 min at 0° under positive pressure of dry Ar
8. 8
   Autrepartitioned between CH2Cl2 and sat. aqueous NaHCO3
9. 9
   SéchageThe organic layer was dried (Na2SO4)
10. 10
    Autreevaporated
11. 11
    Autrechromatographed on a silica gel column (hexane/EtOAc=4/1)

Mode opératoire

A mixture of NaBH (628 mg, 16.6 mmol) and MeOH (50 ml) was cooled and stirred at −70° C. To this was added a mixture of 5 (3.39 g, 8.3 mmol) and CeCl3.7H2O (3.1 g, 8.3 mmol) in THF/MeOH=1/1 (50 ml) dropwise over 15 min. The resulting suspension was stirred for 1 h at the −70□. The reaction was quenched by adding AcOH (ca. 1 mL). The reaction mixture was evaporated. The residue was suspended in MeCN (15 ml). To this suspension were added DMAP (1.02 g, 8.3 mmol), i-Pr2NEt (1.45 mL, 8.3 mmol) and Ac2O (1.57 mL, 16.6 mmol). The mixture was stirred for 30 min at 0° under positive pressure of dry Ar, and partitioned between CH2Cl2 and sat. aqueous NaHCO3. The organic layer was dried (Na2SO4), evaporated, and chromatographed on a silica gel column (hexane/EtOAc=4/1). This gave 6 (3.74 g, 100%) as an oil.

Source