(Triphenylphosphoranylidene)acetaldehyde → methylene-(2S,5R)-6-[(E)-formylmethylene]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate

Participants

Reaction Steps

A solution of 3.8 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 20° with 3.5 g of formylmethylenetriphenylphosphorane. After 10 minutes, the reaction mixture is evaporated. The residue is chromatographed on silica gel while eluting with n-hexane/ethyl acetate (8:2). There are obtained methylene-(2S,5R)-6-[(E)-formylmethylene]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate [Rf: 0.27; cyclohexane/ethyl acetate (8:2); NMR (CDCl3), δ (ppm): 5.68 (1H3); 5.9 (1H5); 6.24 (1H); 10.3 (1H)] and methylene-(2S,5R)-6-[(Z)-formylmethylene]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate [Rf: 0.2; cyclohexane/ethyl acetate (8:2); NMR (CDCl3), δ (ppm): 5.68 (1H3); 6.12 (1H 5); 6.55 (1H); 9.86 (1H)].

Provenance & Evidence