Reaktion #11385

Reaktionsgleichung

2-acetamido-4-fluoro-2,4-dideoxy-D-glucopyranose

acetic anhydride

→

2-acetamido-1,3,6-tri-O-acetyl-2,4-dideoxy-4-fluoro-D-glucopyranose

Lösungsmittel

pyridine

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeclose spots
2. 2
   workup.STIRRINGStirring
3. 3
   workup.WAITcontinued for another 15 hours
4. 4
   SonstigeSolvent was then removed by evaporation in vacuo
5. 5
   Sonstigethen dried in vacuo
6. 6
   workup.ADDITIONpoured in CH2Cl2/acetone (8:1)
7. 7
   WaschenThe column was eluted with 500 ml of CH2Cl2/acetone (8:1)
8. 8
   Wascheneluted immediately
9. 9
   Sonstigewith virtually no separation
10. 10
    SonstigeThe CH2Cl2/CH3OH flush
11. 11
    Sonstigeproduced a trailing spot
12. 12
    SonstigeAll were evaporated
13. 13
    Sonstigedried in vacuo

Vorschrift

A solution of 2-acetamido-4-fluoro-2,4-dideoxy-D-glucopyranose (1.35 g, 6.048 mmol) in a mixture of pyridine (50 ml) and acetic anhydride (25 ml, 27 g, 264 mmol) was stirred at room temperature for 24 hours at which time no starting material but two close spots appeared by TLC. Stirring continued for another 15 hours. Solvent was then removed by evaporation in vacuo; the residue was now co-evaporated with toluene (4×50 ml) then dried in vacuo. This material was now adsorbed on 5 g of silica gel then placed on a silica gel column (45 g, 20×360 mm) poured in CH2Cl2/acetone (8:1). The column was eluted with 500 ml of CH2Cl2/acetone (8:1) followed by 500 ml of CH2Cl2/CH3OH (7:3). The product and trailing spots eluted immediately, with virtually no separation. The CH2Cl2/CH3OH flush produced a trailing spot. All were evaporated and dried in vacuo.

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