Reaction #49987

Reaction equation

(3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(1R)-1-p-methoxybenzyloxycarbonylethyl]azetidin-2-one

p-nitrobenzyl alpha-bromoacetate

sodium hydroxide

→

(3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(1R)-1-p-methoxybenzyloxycarbonylethyl]-1-(p-nitrobenzyloxycarbonylmethyl)azetidin-2-one

Solvents

methylene chloride

water

Conditions

Workup

1. 1
   Extractionextracted with a mixture of diethyl ether and methylene chloride (3:1) three times
2. 2
   WashThe organic layer was washed successively with water two times and brine three times
3. 3
   Dryingdried over sodium sulfate
4. 4
   Otherevaporated
5. 5
   OtherThe residue was purified by silica gel chromatography

Procedure

To a solution of (3S,4S)-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-4-[(1R)-1-p-methoxybenzyloxycarbonylethyl]azetidin-2-one (1.12 g) in methylene chloride (14 ml), there were successively added p-nitrobenzyl alpha-bromoacetate (1.09 g), 50% aqueous sodium hydroxide solution (0.85 g) and triethylbenzylammonium chloride (303 mg), followed by stirring at room temperature for 30 minutes. The reaction mixture was diluted with water and extracted with a mixture of diethyl ether and methylene chloride (3:1) three times. The organic layer was washed successively with water two times and brine three times, 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-p-methoxybenzyloxycarbonylethyl]-1-(p-nitrobenzyloxycarbonylmethyl)azetidin-2-one.

Source