Ammonium Chloride → HCID 88506623, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of diisopropylamine (7.7 ml) in tetrahydrofuran (60.0 ml) was added dropwise a 1.55M solution of n-butyllithium in n-hexane (32.3 ml) at -78° C. The mixture was allowed to warm to 0° C., stirred at 0° C. for 30 minutes, and cooled to -78° C. to give ca. 0.5M lithium diisopropylamide solution. To a solution of allyl 2-[(3S,4R)-3-{(1R)-1-t-butyldimethylsilyloxyethyl}-4-{(1R)-1-methyl-2-oxopropyl}-2-oxoazetidin-1-yl]-2-triphenylphosphoranylideneacetate (2.50 g) in tetrahydrofuran (40 ml) was added dropwise the lithium diisopropylamide solution (9.50 ml) obtained above at -78° C. After stirring for 30 minutes at -78° C., to the mixture was added a solution of (2S)-1-allyloxycarbonyl-2-formylpyrrolidine (1.39 g) in tetrahydrofuran (10.0 ml) and the mixture was allowed to warm to -30° C. over a period of 45 minutes. To this mixture was added aqueous ammonium chloride (50 ml) and diluted with ethyl acetate (200 ml). The organic layer was separated, washed in turn with water, aqueous sodium hydrogen carbonate and brine, and dried over magnesium sulfate. Evaporation of the solvent gave a residue which was chromatographed on silica gel (150 ml) eluting with a mixture of dichloromethane and acetone (9:1-8:2 V/V) to give allyl 2-[(3S,4R)-4-[(1R)-4-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}-4-hydroxy-1-methyl-2-oxobutyl]-3-{ (1R)-1-t-butyldimethylsilyloxyethyl}-2-oxoazetidin-1-yl]-2-triphenylphosphoranylideneacetate (2.36 g).

Provenance & Evidence