Phosphoric Acid → (3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(1R)-1-phenylthiocarbonylethyl]-1-(t-butyloxycarbonylmethyl)azetidin-2-one

Participants

Reaction Steps

To a suspension of sodium hydride (31 mg) in dry dimethylformamide (4.3 ml), there were added successively t-butyl alpha-bromoacetate (835 mg) and (3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(1R)-1-phenylthiocarbonylethyl]azetidin-2-one (0.42 g), and the resultant mixture was stirred at room temperature for 1 hour under a nitrogen stream. The reaction mixture was diluted with diethyl ether and adjusted to pH 6.86 with a phosphoric acid buffer solution. The aqueous layer was separated from the organic layer and extracted with diethyl ether three times. The extracts were combined with the organic layer, washed three times with brine, dried over sodium sulfate and evaporated. The residue was purified by silica gel chromatography to give (3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4[(1R)-1-phenylthiocarbonylethyl]-1-(t-butyloxycarbonylmethyl)azetidin-2-one.

Provenance & Evidence