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), 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.

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% aqueous sodium bicarbonate solution (200 ml) and brine (200 ml)
5. dry with materialdried over anhydrous sodium sulfate
6. filtrationAfter filtration
7. concentrationthe filtrate was concentrated in vacuo
8. customto give an oily residue, which
9. customwas purified by silica gel chromatography

ORD-Eintrag

ord-e9c3816d11564612b043a6679a798d51

Quelldatensatz

uspto-grants-1995_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05424422