Trimethylsilyl triflate → (3S,4R)-4-[(E)-4-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}-3-methyl-2-oxo-3-butenyl]-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-2-oxoazetidine

Temperature

0 °C

To a solution of (2S)-1-allyloxycarbonyl-2-(2-methyl-3-oxo-1-butenyl)pyrrolidine (9.00 g) and triethylamine (6.3 ml) in dichloromethane (200 ml) was added trimethylsilyl trifluoromethanesulfonate (11.7 ml) at -20° C. After stirring at 0° C. for 1 hour, a solution of (3R,4R)-4-acetoxy-3-[(1R)-1-t-butyldimethylsilyloxyethyl]-2-azetidinone (10.9 g) and zinc bromide (11.9 g) in ethyl acetate (70 ml) was added to the mixture and the resultant mixture was stirred at 0° C. for 45 minutes. The reaction mixture was taken up into a mixture of ethyl acetate (600 ml) and water (600 ml). After adjusting pH to 4 with aqueous sodium hydrogen carbonate, the organic layer was separated, washed with brine, dried over magnesium sulfate and evaporated. The residue was chromatographed on silica gel (400 ml) eluting with a mixture of n-hexane and ethyl acetate (9:1-5:5 V/V) to give (3S, 4R)-4-[(E)-4-{(2S)-1-allyloxycarbonylpyrrolidin-2-yl}-3-methyl-2-oxo-3-butenyl]-3[(1R)-1-t-butyldimethylsilyloxyethyl]-2-oxoazetidine (9.96 g).

1. customthe organic layer was separated
2. washwashed with brine
3. dry with materialdried over magnesium sulfate
4. customevaporated
5. customThe residue was chromatographed on silica gel (400 ml)
6. washeluting with a mixture of n-hexane and ethyl acetate (9:1-5:5 V/V)

ORD record

ord-8f81568565424a61bf1b2b9db9367f35

Source dataset

uspto-grants-1990_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04923857