A New Method for the Synthesis of 3-Methylene-2-azetidinones

The reaction of N-monosubstituted 2-[(tributylstannyl)-methyl]propenamides with dioxane dibromide affords N-monosubstituted 2-(bromomethyl)-propenamides which upon treatment with sodium hydride or potassium t-butoxide are converted to 3-methylene-2-azetidinones in good yields.