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

Participants

Reaction Steps

A solution of 6.6 g of methylene-6,7-dioxo-3,3-dimethyl-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate in 150 ml of benzene is treated at room temperature with 9 g of triphenylchloroacetonylphosphorane. After 10 minutes, the reaction mixture is evaporated. The residue is chromatographed on silica gel while eluting with cyclohexane/ethyl acetate (7:3). There is obtained methylene-(2S,5R)-6-(3-chloroacetonylidene)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate as an orange oil [Rf: 0.4; cyclohexane/ethyl acetate (6:4); NMR (CDCl3), δ (ppm); 1.21 (9H); 1.51 (3H); 1.57 (3H); 4.25 (2H); 4.65 (1H); 5.9 (m, 2H); 6.1 (1H); 6.93 (1H)].

Provenance & Evidence