Water → allyl (5R,6S)-3-(1-allyloxycarbonylpyrrolidin-3-yl)-6-[(1R)-1-t-butyldimethylsilyloxyethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of (3S,4R)-4-[2-(1-allyloxycarbonylpyrrolidin-3-yl)-2-oxoethyl]-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-2-oxoazetidine (2.13 g) and triethylamine (1.4 ml) in dichloromethane (30 ml) was added allyl oxalyl chloride (1.1 g) at -20° C. under nitrogen, and the resulting mixture was stirred for 30 minutes at -20° C. The reaction mixture was taken up into a mixture of water and ethyl acetate. The organic layer was separated, washed in turn with water, aqueous sodium hydrogen carbonate and brine, dried over magnesium sulfate, and evaporated. To a solution of the residue in xylene (30 ml) was added triethyl phosphite (5.2 ml). The resulting mixture was heated at 90° C. for 15 hours under nitrogen, and then to the mixture was added hydroquinone (0.9 g) and the mixture was heated at 130° C. for 2 hours under nitrogen. Evaporation of the solvent gave a residue, which was chromatographed on silica gel eluting with a mixture of n-hexane and ethyl acetate (4:1, V/V) to give allyl (5R,6S)-3-(1-allyloxycarbonylpyrrolidin-3-yl)-6-[(1R)-1-t-butyldimethylsilyloxyethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (2.9 g).

Provenance & Evidence