Citric Acid → tert-butyl N-((2S)-1-oxobutan-2-yl)carbamate

A solution of tert-butyl[(1S)-1-(hydroxymethyl)propyl]carbamate (30.0 g) in dimethyl sulfoxide (300 mL) was ice-cooled under a nitrogen atmosphere, and triethylamine (64.4 mL) and a solution of sulfur trioxide pyridine complex (80.7 g) in dimethyl sulfoxide (300 mL) were successively added. The mixture was stirred at the same temperature for 30 min and then at room temperature for 3 hr, 1 mol/L aqueous citric acid solution (500 mL) was added to the reaction solution, and the mixture was extracted with diethyl ether. The obtained organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=0→30%) to give the title compound as a white powder (yield: 24.3 g, 85%).

1. temperaturecooled under a nitrogen atmosphere
2. waitat room temperature for 3 hr
3. extractionthe mixture was extracted with diethyl ether
4. washThe obtained organic layer was washed with water and saturated brine
5. dry with materialdried over anhydrous magnesium sulfate
6. concentrationconcentrated under reduced pressure
7. customThe residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=0→30%)

ORD record

ord-b3ed2376e8e742e5a49f3fbbb25067e0

Source dataset

uspto-grants-2013_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08420694B2