Methoxymethyl-triphenylphosphonium chloride → Benzyl ((2R,3S)-1-(2,4-dimethoxybenzyl)-2-((E)-2-methoxyvinyl)-4-oxoazetidin-3-yl)carbamate

Participants

Reaction Steps

To a suspension of (methoxymethyl)triphenylphosphonium chloride (10.34 g, 30.2 mmol) in THF (100 mL) at −78° C. was added KHMDS (in toluene) (66.3 ml, 33.1 mmol) slowly. After stirring for 30 min, the above prepared ylide soln was added to a soln of benzyl ((2S,3S)-1-(2,4-dimethoxybenzyl)-2-formyl-4-oxoazetidin-3-yl)carbamate (3 g, 7.53 mmol) in THF (38 ml) at −78° C. After 3 h, the reaction mixture was quenched with saturated NaHCO3 (aq, 60 mL), and it was stirred overnight. The mixture was diluted with EtOAc, and the layers were separated. The aqueous layer was extracted with EtOAc (2×), and the combined organic layers were washed with brine, dried with Na2SO4 and concentrated in vacuo. The crude residue was purified via silica gel chromatography (EtOAc-Heptane, 0-60%) to afford the title compound (1.6 g, 49%) along with the trans-isomer (0.8 g, 25%). LCMS: Rt=0.91 min, m/z=427.0 (M+1). Method 2m_acidic.

Provenance & Evidence