Reacción #92525

Ecuación de reacción

BnBr

sodium methoxide

3,4,6-Tri-O-acetyl-D-glucal

NaH

→

3,4,6-tri-O-benzyl-D-glucal

Rendimiento 94.0%

Disolventes

methanol

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe solvent was removed
2. 2
   TemperaturaTHF and cooled to 0° C
3. 3
   workup.STIRRINGThe reaction mixture was stirred at room temperature overnight
4. 4
   Otroquenched with methanol
5. 5
   Otrothe solvent removed
6. 6
   Lavadowashed with 1 N HCl, brine, and saturated NaHCO3 (100 mL each)
7. 7
   SecadoThe ethyl acetate solution was dried over MgSO4
8. 8
   Filtraciónfiltered
9. 9
   Concentraciónconcentrated in vacuo
10. 10
    OtroThe crude material was purified on a silica gel column (80 g)
11. 11
    Lavadoeluting with a 0→50% gradient of ethyl acetate in heptane

Procedimiento

3,4,6-Tri-O-acetyl-D-glucal (5.0 g, 18.4 mmol) was dissolved in methanol (100 mL) and a solution of sodium methoxide in methanol (0.25 mL, 25% solution by weight, 1.1 mmol). The solution was stirred at room temperature for 3 hours. The solvent was removed and the resulting residue was co-evaporated with toluene (3×10 mL) before being taken up in a 4:1 solution of NMP:THF and cooled to 0° C. Solid NaH (3.3 g of 60% suspension, 82.5 mmol) was added and the mixture was stirred for 30 minutes before the addition of BnBr. The reaction mixture was stirred at room temperature overnight, quenched with methanol and the solvent removed. The residue was suspended in ethyl acetate, washed with 1 N HCl, brine, and saturated NaHCO3 (100 mL each). The ethyl acetate solution was dried over MgSO4, filtered and concentrated in vacuo. The crude material was purified on a silica gel column (80 g) using an ISCO automated chromatography system, eluting with a 0→50% gradient of ethyl acetate in heptane, to give 3,4,6-tri-O-benzyl-D-glucal (7.2 g, 94%).

Fuente