Oxygen → HCID 20659833, compound

Participants

Reaction Steps

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).

Provenance & Evidence