Oxygen → HCID 20659833, compound

To a solution of diisopropylamine (800 μL, 5.7 mmol) in anhydrous THF (40 mL) at −20° was added butyllithium (3.56 mL, 5.7 mmol, 1.6 M in hexane). After 15 min., the reaction was cooled to −78°, and freshly distilled trimethylphosphite (1.12 mL, 7.6 mmol) was added followed by a solution of 4(S)-benzyl-1-(tert-butyldimethylsilyl)azetidin-2-one (from example 1, step C, 1.05 g, 3.8 mmol) in THF (10 mL). A constant stream of oxygen was introduced and the mixture was stirred at −78° for 3 h. The reaction mixture was quenched with saturated aqueous NH4Cl and extracted with EtOAc (120 mL). The organic layer was washed with brine, dried (MgSO4), filtered and concentrated. The residue was purified by flash chromatography (SiO2, 10% EtOAc-hexane to 30% EtOAc in hexane) to give 4(S)-benzyl-1-(tert-butyldimethylsilyl)-3(S)-hydroxyazetidin-2-one (671 mg , 60% yield) as a white solid. 1H-NMR (400 MHz, CDCl3) δ7.25-7.21 (m, 5H), 4.51 (d, J=2 Hz, 1H), 3.75-3.71 (m, 1H), 3.26 (bs, 1H), 3.20 (dd, J=14, 3.8 Hz, 1H), 2.66 (dd, J=14, 11.1 Hz, 1H), 1.00 (s, 9H), 0.30 (d, J=3.5 Hz, 6H).

1. temperaturethe reaction was cooled to −78°
2. customThe reaction mixture was quenched with saturated aqueous NH4Cl
3. extractionextracted with EtOAc (120 mL)
4. washThe organic layer was washed with brine
5. dry with materialdried (MgSO4)
6. filtrationfiltered
7. concentrationconcentrated
8. customThe residue was purified by flash chromatography (SiO2, 10% EtOAc-hexane to 30% EtOAc in hexane)

ORD record

ord-ac857679e9d04b2bb68448d2a60f577a

Source dataset

uspto-grants-2001_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06242439B1