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

Participants

Reaction Steps

A solution of 3.2 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 5 g of cyanomethylenetriphenylphosphorane. After 10 minutes, the reaction mixture is evaporated. The residue is chromatographed on silica gel with cyclohexane/ethyl acetate (7:3). There are obtained methylene-(2S,5R)-6-[(Z)-cyanomethylene]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate as a reddish oil [Rf: 0.38; cyclohexane/ethyl acetate (6:4); NMR (CDCl3) δ (ppm): 1.24 (9H); 1.53 (3H); 1.59 (3H); 4.59 (1H); 5.84 (2H); 5.89 (1H); 5.97 (1H)] and methylene-(2S,5R)-6-[(E)-cyanomethylene]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate pivalate as a reddish oil [Rf: 0.33; cyclohexane/ethyl acetate (6:4); NMR (CDCl3), δ (ppm): 1.24 (9H); 1.51 (3H); 1.6 (3H); 4.64 (1H); 5.59 (1H); 5.84 (3H)].

Provenance & Evidence