Methylsulphonylacetylmethylenetriphenylphosphorane → methylene-(2S,5R)-3,3-dimethyl-7-oxo-6-[3-methylsulphonyl-2-oxopropylidene]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate

Participants

Reaction Steps

A solution of 2.3 g of methylene-6,7-dioxo-3,3-dimethyl-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate in 75 ml of benzene is treated at room temperature with 4 g of methylsulphonylacetylmethylenetriphenylphosphorane. After 10 minutes, the reaction mixture is evaporated. The residue is chromatographed on silica gel while eluting with cyclohexane/ethyl acetate (1:1). There is obtained methylene-(2S,5R)-3,3-dimethyl-7-oxo-6-[3-methylsulphonyl-2-oxopropylidene]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate as an orange oil [Rf: 0.23; cyclohexane/ethyl acetate (1:1); NMR (CDCl3), δ (ppm): 1.22 (9H); 1.5 (3H); 1.56 (3H); 3.03 (3H, CH3 --SO2); 4.24 (2H, --CH2 --SO2); 4.59 (1H); 6.02 (1H); 6.79 (1H)].

Provenance & Evidence