Boron trifluoride etherate → (3S,4S)-4-(1-(R)-hydroxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-2-azetidinone

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) 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% sodium bicarbonate (200 ml) and brine (200 ml) and dried over anhydrous sodium sulfate. Filtration and concentration of the filtrate in vacuo gave an oily residue which was purified by silica gel chromatography to yield (3S,4S)-4-(1-(R)-hydroxymethylethyl)-3-(1-(R)-benzyloxycarbonyloxyethyl)-2-azetidinone.

1. temperatureby heating
2. temperatureunder reflux for 3-5 hours
3. temperatureThe reaction mixture was cooled down to 10°-15° C.
4. washwashed successively with brine (200 ml×2), 2.5% sodium bicarbonate (200 ml) and brine (200 ml)
5. dry with materialdried over anhydrous sodium sulfate
6. filtrationFiltration and concentration of the filtrate in vacuo
7. customgave an oily residue which
8. customwas purified by silica gel chromatography

ORD-Eintrag

ord-ca7f59f82f7343c2823d7361a964354d

Quelldatensatz

uspto-grants-1992_05

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05112966