3-Methyl-1-(triphenylphosphoranylidene)butan-2-one → methylene-(2S,5R)-3,3-dimethyl-6-(3-methyl-2-oxobutylidene)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate

Participants

Reaction Steps

A solution of 5.4 g of methylene-6,7-dioxo-3,3-dimethyl-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate in 100 ml of benzene is treated at room temperature with 8.8 g of dimethylacetylmethylenetriphenylphosphorane. After 10 minutes, the reaction mixture is evaporated. The residue is chromatographed on silica gel while eluting with cyclohexane/ethyl acetate (6:4). There is obtained methylene-(2S,5R)-3,3-dimethyl-6-(3-methyl-2-oxobutylidene)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate as a yellow oil [Rf: 0.35; cyclohexane/ethyl acetate (6:4); NMR (CDCl3), δ (ppm): 1.12 (6H); 1.25 (9H); 1.51 (3H); 1.6 (3H); 2.77 (2H); 4.6 (1H); 5.89 (2H); 6.05 (1H); 6.72 (1H)].

Provenance & Evidence