Reaktion #49997

Reaktionsgleichung

(3S,4R)-4-(1-(R)-t-butyldimethylsilyloxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone

1,3-dimethoxybenzene

boron trifluoride etherate

→

(3S,4S)-4-(1-(R)-hydroxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-2-azetidinone

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturby heating
2. 2
   Temperaturunder reflux for 3-5 hours
3. 3
   TemperaturThe reaction mixture was cooled down to 10°-15° C.
4. 4
   Waschenwashed successively with brine (200 ml×2), 2.5% aqueous sodium bicarbonate solution (200 ml) and brine (200 ml)
5. 5
   Trocknendried over anhydrous sodium sulfate
6. 6
   FiltrationAfter filtration
7. 7
   Einengenthe filtrate was concentrated in vacuo
8. 8
   Sonstigeto give an oily residue, which
9. 9
   Sonstigewas purified by silica gel chromatography

Vorschrift

To a solution of (3S,4R)-4-(1-(R)-t-butyldimethylsilyloxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-1-di(p-anisyl)methyl-2-azetidinone (20 g) in dry dichloromethane (200 ml), there were added 1,3-dimethoxybenzene (7.8 g) and boron trifluoride etherate (23 g) at 10°-20° C., and the resultant mixture was stirred at room temperature for 3 hours, followed by heating under reflux for 3-5 hours. The reaction mixture was cooled down to 10°-15° C., washed successively with brine (200 ml×2), 2.5% aqueous sodium bicarbonate solution (200 ml) and brine (200 ml) and dried over anhydrous sodium sulfate. After filtration, the filtrate was concentrated in vacuo to give an oily residue, which was purified by silica gel chromatography to yield (3S,4S)-4-(1-(R)-hydroxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-2-azetidinone.

Quelle